BACKGROUND OF THE INVENTION Mesenchymal stem cells (MSCs) are known to be useful in regenerative medicine and tissue engineering. In adults, bone marrow, adipose tissue, dental pulp, and menstrual blood are the main sources of MSCs. They can also be obtained by cultivating placental cells or umbilical cord cells for 3-4 weeks in FCS-supplemented DMEM ([12], [13], [14]).

MSCs have a mesodermal, ectodermal and endodermal differentiation potential. MSCs also have immunosuppressive properties. MSCs inhibit or halt maturation of dendritic cells and proliferation of T cells, B cells and NK cells. Their immunomodulatory action is mediated by the cytokines and chemokines they secrete. Several groups have demonstrated that MSCs within placental tissue display multi-lineage developmental plasticity in vitro and in vivo. Placental tissue (including umbilical cord, umbilical cord blood, placenta, chorion, amnion and amnion fluid) - derived MSCs show positive expression of CD29, CD44, CD73, CD90 and CD105, negative expression for hematopoietic surface markers CD11 b, CD19, CD34 and CD45, and negative expression for the endothelial surface marker CD31. In addition, placental tissue-derived MSCs are able to trans-differentiate into cells of all three germ layers in appropriate conditions (e.g. a complete media). Perinatal tissue-derived MSCs have also been shown to possess broad immunoregulatory capabilities and are capable of influencing both adaptive and innate immune responses. These MSCs inhibit immune cells proliferation and maturation and suppress immune reactions both in vitro and in vivo in a non-MHC restricted manner. Therefore, these MSCs are considered to be hypoimmunogenic, displaying low expression levels of HLA class I, no expression of HLA class II, and no expression of costimulatory molecules, including CD40, CD80, and CD86. Basically, these MSCs could exert widespread immunomodulatory effects on cells of both the innate and adaptive immune system. Ex-vivo expanded placenta MSCs have also been showed to suppress the activity of a broad range of immune cells, including T cells, natural killer T (NKT) cells, dendritic cells (DCs), B cells, neutrophils, monocytes, macrophages and so on.

Human perinatal tissue-derived MSCs are also safe according to numerous clinical trial reports. The safety and initial efficacy of umbilical cord derived MSCs (UC-MSCs) transfusions for acute-on-chronic liver failure (ACLF) patients associated with hepatitis B virus (HBV) infection was assessed. These results suggested that MSCs transfusions are safe in the clinic and may serve as a novel therapeutic approach for HBV-associated ACLF patients [1]. The safety and efficacy of human UC-MSCs in the treatment of rheumatoid arthritis (RA) also was assessed. These results showed that no serious adverse effects were observed during or after infusion. Furthermore, the treatment of MSCs induced a significant remission of disease according to the 28-joint disease activity score [2]. Scientists evaluated the safety and feasibility of intramyocardial MSCs injection in nine patients, shortly after acute myocardial infarction (AMI) during short-term and 5-year follow-up [3]. These results suggested that intramyocardial injection of MSCs in patients shortly after AMI is feasible and safe up to 5-year follow-up. A prospective double blind randomized placebo controlled multi-center study to determine the safety of MSCs in patients with critical limb ischemia showed that MSCs are also safe when injected intramuscularly at a dose of 2 million cells/kg body weight [4]. No neoplastic complications were detected at any MSCs implantation sites. Hongye Fan et al ([15]) showed that the transplantation of IL1 β primed MSCs has an enhanced therapeutical efficiency in DSS-induced murine colitis, which depends on their increased immunosuppressive capacities and enhanced migration ability. WO 2014/093948 also disclosed the therapeutic value of purified MSCs.

However, the definition of MSCs has always been controversial because there is no specific or unique cell surface marker identifying them unambiguously. To date, MSCs have been defined by using a combination of cell surface phenotypic protein markers, plastic adherent fibroblast-like growth and functional properties. Yet, there are several different subpopulations according to these cell surface markers and these different subpopulations show different biological characteristics, biological functions and are not all efficient in treatment protocols. For example, some MSC populations are stimulated by I L1 β ([12]), whereas other populations are not (the CD106 positive MSCs in [15]). Additionally, the proliferation of some MSC populations is inhibited by IL4 ([12]), whereas other are induced to proliferation in the presence of this cytokine ([13]). There is therefore an urgent need to identify a population of functional MSCs that have a clinical efficiency and standardize their preparation process. It is also important to set up a protocol that can be used on every placental and extra-embryonic tissue interchangeably. More precisely, it is important to identify a preparation process that yields therapeutically efficient MSC populations either from placental tissue or from umbilical cord fragments. Meanwhile, there is currently a high demand of human MSCs for numerous therapeutic applications but insufficient availability in the market. There is therefore a need for an industrial scale process giving a high yield of functional MSCs. There is also a need for an efficient culturing system that gives an optimum yield at an affordable cost, thereby reducing the demand-supply gap, for MSCs obtained from all placental and extraembryonic tissues. The present application fulfills all these needs and others, by proposing an optimal method for generating and purifying MSCs subpopulations of different origins (either from placental tissue or from umbilical cord) and ultimately expanding said subpopulation with the least possible passages and minimal number of population doublings. This method leads to the recovery, from placental and from umbilical cord tissues, of highly potent MSCs having a multilineage differentiation capacity. This method reproducibly provides with a considerable number of MSC cells that are suitable for clinical application.

DETAILED DESCRIPTION OF THE INVENTION

Example 1 (see below) discloses a preparation method for generating human placenta tissue derived CD106 ^high CD151 ⁺ Nestin ⁺ mesenchymal stem cells (MSCs) at industrial scale, enabling to obtain a yield of at least 1x10 ⁵ cells/cm ² MSCs which are prepared in a GMP-compliant facility and are suitable for allogenic use. Said placental tissue derived CD106 ^high CD151 ⁺ Nestin ⁺ mesenchymal stem cells (MSCs) comprise over 95% of cells which express the positive markers CD73, CD90, CD105 and CD166, and less than 2% of cells which express the negative markers CD45, CD34 and HLA-DR. This method is useful for generating cells that can be used in transplantation trials into a human subject or in an animal.

It comprises the two following general steps:

(i) Culturing mesenchymal stem cells obtained from a biological tissue or fluid in a first culture medium deprived of growth factors, so as to generate a population of cultured undifferentiated mesenchymal stem cells, and

(ii) contacting said population of cultured undifferentiated mesenchymal stem cells with a second culture medium containing pro-inflammatory growth factors or inflammatory mediators, thereby generating CD106 ^high CD151 ⁺ Nestin ⁺ mesenchymal stem cells useful for transplantation into a subject in need thereof.

In a first aspect, the invention relates to an in vitro method to prepare CD106 ^high CD151 ⁺ Nestin ⁺ mesenchymal stem cells (MSCs) at industrial scale, said method comprising culturing a population of undifferentiated MSCs in a culture medium comprising pro-inflammatory growth factors or inflammatory mediators. Said "population of undifferentiated MSCs" can be obtained by collecting the mononuclear cells present in a biological tissue or fluid and growing them in a first culture medium. These mononuclear cells can be obtained by any conventional means, e.g., by enzymatic digestion or explant culture of perinatal tissue pieces [10] or isolation from biological fluids [11]. Explant culture is a particularly preferred process for deriving MSC from umbilical cords, as exposed in example 3 below.

Typically, this process requires to remove the sample from the transport solution, to cut it in sections (roughly 2-3cm long), to disinfect them with antibiotics and antifungal agents that are rinsed afterwards, to recover the epithelial membrane and dispose pieces of said membrane in flasks for them to adhere (preferably without medium, at room temperature), before complete medium is added carefully on the adhered explants and keep incubated at 37°C for several days. The migrated cells are eventually collected with appropriate tools and maintained in culture in the appropriate first medium (see below) until they reach the target confluency. Said "first culture medium" can be any classical medium commonly used to favor growth of living primary cells. Preferably, it does not contain any growth factors nor any differentiation factors.

The skilled person well knows what kind of culture media can be used as "first culture medium". They are for example DMEM, DMEM/F12, MEM, alpha-MEM (a-MEM), IMDM, or RPMI. Preferably, said first culture medium is DMEM (Dulbecco's Modified Eagle's Medium) or DMEM/F12 (Dulbecco's Modified Eagle's Medium: Nutrient Mixture F-12).

More preferably, said first culture medium contains 2-20% or 2-10% of fetal bovine serum. Alternatively, said first culture medium may contain 1-5% platelet lysate. A most preferred medium contains 2-20% or 2-10% of fetal bovine serum and 1-5% platelet lysate. It is also possible to use as first culture medium a medium which is devoid of serum or platelet lysate, provided that it contains other appropriate agents favoring the growth of primary living cells.

In a preferred embodiment, said "biological tissue" is any portion of a placental tissue, or of umbilical cord. In particular, it can include or consist in placental cotyledons, the amnion membrane or the chorionic membrane of the placenta. Also, it can be the Wharton jelly found in the umbilical cord. It can include the veins and/or the arteries, or be deprived thereof.

In another embodiment, said "biological fluid" is a sample of umbilical cord blood, of placenta blood or of amniotic fluid, which have been harmlessly collected from a woman or a mammal in general. For example, these tissues and fluids can be obtained after the delivery of a baby or an offspring, without any invasive proceedings.

Said population of undifferentiated MSCs is preferentially a population of mesenchymal stem cells seeded on a plastic surface, which has been cultured in said first culture medium devoid of any growth factor until the cells reach a confluency of 85-90%.

Regularly, the cells are phenotypically characterized by FACS or any conventional means, in order to detect the level of the surface markers CD73, CD90, CD105, CD166, CD45, CD34 and HLA-DR.

When 95% of the cells express the positive surface markers CD73, CD90, CD105 and CD166, and less than 2% express the negative surface markers CD45, CD34 and HLA-DR, the cells are trypsinized and seeded again at a lower density, e.g. at a density of 1000 to 5000 MSCs per cm ² into a second culture medium.

Preferably, said "second culture medium" is any classical medium commonly used to favor living primary cells growth. It can be the same medium as the "first culture medium", or it can be another one, chosen for example among DMEM, DMEM/F12, MEM, alpha-MEM (a-MEM), IMDM, or RPMI. More preferably, said second culture medium is DMEM (Dulbecco's Modified Eagle's Medium) or DMEM/F12 (Dulbecco's Modified Eagle's Medium: Nutrient Mixture F-12).

Even more preferably, said second culture medium contains serum or platelet lysate, for example between 2-20% of fetal bovine serum and/or 1-5% platelet lysate. A most preferred second medium is DMEM containing 2-20% of fetal bovine serum and 1-5% platelet lysate. It is also possible to use as second culture medium a medium which is devoid of serum or platelet lysate, provided that it contains other appropriate agents favoring the growth of primary living cells.

When the cells reach 40-50% confluency, pro-inflammatory growth factors or inflammatory mediators are added to the second culture medium and the cells are cultured in said medium until they reach 90-95% confluency. Said "pro-inflammatory growth factors" are typically interleukins or chemokines that are known to have a pro-inflammatory effect. Examples of interleukins that can be added in the second culture medium include TNFa, IL1 , IL4, IL12, IL18, and IFNy. Examples of chemokines that can be added in the second culture medium include CXCL8, CXCL10, CXCL1 , CXCL2, CXCL3, CCL2, and CCL5. Other inflammatory mediators (such as anti-inflammatory agents) can be used.

In a preferred embodiment, at least two pro-inflammatory growth factors are added in the second culture medium defined above. These at least two pro-inflammatory growth factors are chosen in the group consisting of: TNFa, IL1 , IL4, IL12, IL18, and IFNy. In a more preferred embodiment, said pro-inflammatory growth factors are chosen among IL1 , IL4, IL12, IL18. Even more preferably, they are IL1 and IL4.

A typical concentration of growth factor(s) that can be added to the MSCs is comprised between 1-200 ng/mL, preferably between 1-100 ng/mL, more preferably between 10-80 ng/mL. Preferably, the culturing step of the MSCs with the growth factor(s) lasts for at least one day, more preferably for two days. The term "IL1 " herein designates any isoform of Interleukin 1 , in particular, IL1 a and IL1 β.

IL1 isoforms may be of various origins, depending on the intended application. For example, animal IL1 may be used for veterinary applications. Preferably, only I L1 β is added in the second culture medium of the invention. In this particular embodiment, the concentration of added Interleukin 1 β can be comprised between 1-100 ng/mL, preferably between 1-50 ng/mL, more preferably between 10-40 ng/mL. Human ILI beta (IL1 β) is referenced to as accession number NP_000567.1 (SEQ ID NO:6, 269 amino acids). Recombinant protein is commercially available in GMP conditions (RnD systems, Thermofisher, Cellgenix, Peprotech).

The term "IL4" herein designates any isoform of Interleukin 4. IL4 may be of various origins, depending on the intended application. For example, animal IL4 may be used for veterinary applications.

Human IL4 is referenced to as accession number AAA59149 (SEQ ID NO:7, 153 amino acids). Recombinant protein is commercially available in GMP conditions (RnD systems, Thermofisher, Cellgenix, Peprotech). Any mixture of different pro-inflammatory growth factors can be used in the second medium of the invention. In particular, it is a preferred embodiment to use a mixture of IL1 and IL4, more precisely, of I L1 β and IL4, as disclosed in the experimental part below.

In this particular embodiment, the added Interleukin 1 β has a concentration comprised between 1-100 ng/mL, preferably between 1-50 ng/mL, more preferably between 10-40 ng/mL. and the added IL4 has a concentration comprised between 1-100 ng/mL, preferably between 1-50 ng/mL, more preferably between 10-40 ng/mL in the second culture medium. Preferably, the culturing step with Interleukin 1 β and IL4 lasts for at least one day, more preferably for two days.

In a final step, the cells are phenotypically characterized by any conventional means, in order to detect the level of surface markers CD73, CD90, CD105, CD166, CD45, CD34 and HLA-DR. These markers are well-known in the art. Antibodies useful for detecting the expression level of these markers are all commercially available.

Expression of these cell surface markers may be notably assessed using well known technologies such as cell membrane staining using biotinylation or other equivalent techniques followed by immunoprecipitation with specific antibodies, flow cytometry, western blot, ELISA or ELISPOT, antibodies microarrays, or tissue microarrays coupled to immunohistochemistry. Other suitable techniques include FRET or BRET, single cell microscopic or histochemistry methods using single or multiple excitation wavelength and applying any of the adapted optical methods, such as electrochemical methods (voltametry and amperometry techniques), atomic force microscopy, and radio frequency methods, e.g. multipolar resonance spectroscopy, confocal and non-confocal, detection of fluorescence, luminescence, chemiluminescence, absorbance, reflectance, transmittance, and birefringence or refractive index (e.g., surface plasmon resonance, ellipsometry, a resonant mirror method, a grating coupler waveguide method or interferometry), cell ELISA, , radioisotopic, magnetic resonance imaging, analysis by polyacrylamide gel electrophoresis (SDS-PAGE); HPLC-Mass Spectroscopy; Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC-MS/MS).

Preferably, the levels of cell surface markers are assessed by FACS. In other words, the method of the invention typically requires to : a) collect the mononuclear cells contained in a perinatal biological tissue or fluid, b) allow said mononuclear cells to grow into a first culture medium until they reach 85-90% confluence, preferably on a plastic surface, c) once 95% of the cells express the positive markers CD73, CD90, CD105 and CD166, and less than 2% express the negative markers CD45, CD34 and HLA-DR, seed the cells at a density of 1000 to 5000 MSCs per cm ² into a second culture medium, d) add between 1-100ng/mL of inflammatory mediators or pro-inflammatory growth factors once the cells reach 40-50% confluency, e) collect the cells when they reach 90-95% confluency.

The collected cells may then be phenotypically characterized by FACS or any conventional means, in order to detect the level of surface markers CD73, CD90, CD105, CD166, CD45, CD34 and HLA-DR. Said first and second culture media have been described above. In step d) of said method, the typical concentration of added growth factor(s) is comprised between 1-200 ng/mL, preferably between 1-100 ng/mL, more preferably between 10-80 ng/mL. Preferably, the culturing step with growth factor(s) lasts for at least one day, more preferably for two days. In a particular embodiment of the invention, the concentration of added Interleukin 1 β or IL4 can be comprised between 1-100 ng/mL, preferably between 1-50 ng/mL, more preferably between 10-40 ng/mL. Preferably, the culturing step with Interleukin 1 β and IL4 lasts for at least one day, more preferably for two days.

The final collected cells will be the "cell culture of the invention", or "CD106 ^h ' ^9h CD151* Nestin* MSCs of the invention" or "MSCs of the invention". This cell culture typically comprises over 60%, preferably between 60 and 70%, preferably over 70%, preferably over 80%, more preferably over 90% and even more preferably over 95% of cells expressing CD106. Moreover, it comprises over 98%, preferably over 99% of cells expressing CD151. Moreover, it comprises over 98%, preferably over 99% of cells expressing Nestin, Finally, it comprises over 95%, preferably over 96%, preferably over 97%, preferably over 98% of cells expressing the positive markers CD73, CD90, CD105 and CD166, and comprises less than 2% cells expressing the negative markers CD45, CD34 and HLA-DR.

CD106 (also known as VCAM-1 for "vascular cell adhesion protein 1 ") is known to have three isoforms. NP_001069.1 (herein referred to as SEQ ID NO:1 , 739 amino acids), NP_542413.1 (herein referred to as SEQ ID NO:2, 647 amino acids) and NP_001186763.1 (herein referred to as SEQ ID NO:3, 677 amino acids) are the sequences of the isoforms a, b and c respectively. Antibodies to detect the level of expression of this particular biomarker are commercially available (for example by Thermofisher, Abeam, OriGen, etc.). The expression of this marker at the surface of the cells of the invention is very important, as it triggers pro-angiogenic activities that are essential for their therapeutic use. The nestin biomarker (herein referred to as SEQ ID NO:4, 1621 amino acids) is referenced under the number NP_006608.1 in humans. Antibodies to detect the level of expression of this particular biomarker are commercially available (for example by Thermofisher, Abeam, etc.).

The CD151 biomarker (herein referred to as SEQ ID N05, 253 amino acids) is referenced under the number NP_620599 in humans. Antibodies to detect the level of expression of this particular biomarker are commercially available (for example by Invitrogen, Sigma-Aldrich, Abeam, etc.).

In a preferred embodiment, the culturing steps (or growing steps) are performed on a plastic surface. More specifically, the method of the invention may comprise the steps of:

a) Optionally separately collecting placental tissues from multiple donors;

b) Optionally washing the placental tissue three times using 1X PBS, dissected in 1 mm ³ cubes and washing the cubes tissue again to remove most of the blood from the tissue.

c) Optionally digesting the placental tissue of each donor separately with collagenase, centrifuging the digested tissue and collecting the mononuclear cells,

d) Seeding the collected mononuclear cells into a culture medium;

e) Trypsinizing and passage the cells once they reach 85-90% confluence;

f) Characterizing the cells based on the percentage of cells which express positive markers CD73, CD90, CD105 and CD166, and negative markers CD45, CD34 and HLA-DR;

g) Seeding the cells in a culture medium containing 90% Dulbecco's Modified Eagle's Medium/F12-Knockout (DMEM/F12-KO) and 10% FBS and growth factors at a seeding density of 1000 to 5000 MSCs per cm ² when they comprise at least 95% of the positive markers and at most 2% of the negative markers,

h) Adding between 1-100ng/ml_ of interleukin 1 β and optionally between 1-100ng/ml_ of IL4 when they are 40-50% confluent;

i) Trypsinizing and collecting the cells once they reach 90-95% confluence; and j) Optionally characterizing the cells based on the percentage of cells which express positive markers CD73, CD90, CD105 and CD166, and negative markers CD45, CD34 and HLA-DR. The results disclosed below show that the expression of CD106 is greatly enhanced at the surface of the MSCs obtained by the method of the invention either from umbilical cord or placenta. This expression is of high importance for the therapeutic use of the thus generated cells (see below).

The present application therefore also relates to a method to enhance the CD106 expression level of undifferentiated MSCs, said method comprising culturing a population of undifferentiated MSCs in the particular conditions exposed thoroughly above, all the detailed embodiments applying mutatis mutandis.

In another aspect, the invention relates to a cell culture obtained by the above-described method. This cell culture typically contains isolated CD106 ^high CD151 ⁺ Nestin ⁺ MSCs expressing the vascular cell adhesion molecule 1 (VCAM-1 ) marker at a detectably higher level than mesenchymal stem cells derived from adult bone marrow, adipose tissue, umbilical cord or placenta that have not been in contact with any growth factors during their preparation.

In a preferred embodiment, the cell culture of the invention is characterized in that:

(i) over 60%, preferably over 70%, more preferably over 80% and even more preferably over

90% of cells express CD106 at a detectable level, and

(ii) over 98%, preferably over 99% of cells express CD151 at a detectable level, and

(iii) over 90%, preferably over 92%, more preferably over 95% of cells express Nestin at a detectable level, and

(iv) over 95%, preferably over 96%, preferably over 97%, preferably over 98% of cells expressing the positive markers CD73, CD90, CD105 and CD166 at a detectable level. In a more preferred embodiment, the said cell culture is characterized in that it contains over 98% of MSCs that do not express the markers CD11 b, CD14, CD15, CD16, CD31 , CD34, CD45, CD49f, CD102, CD104 and CD133 at a detectable level. These markers are well-known in the art and antibodies detecting same are commercially available.

In a preferred embodiment, the cell culture of the invention contains:

- over 60%, preferably over 70%, more preferably over 80% and even more preferably over 90% of cells expressing CD106 at a detectable level, and

- over 98%, preferably over 99% of cells expressing CD151 at a detectable level, and - over 98%, preferably over 99% of cells expressing Nestin at a detectable level, and

- over 95%, preferably over 96%, preferably over 97%, preferably over 98% of cells expressing the markers CD73, CD90, CD 105 and CD 166 at a detectable level, and

- less than 2% of cells which express the markers CD45, CD34 and HLA-DR at a detectable level. According to the present invention, a cell "expresses a marker at a detectable levef if said marker is present at a significant level on its surface, i.e., if the signal associated to the staining of said surface marker (typically obtained with an antibody recognizing said marker, said antibody being for example coupled to a fluorescent dye) which is measured for said cell is superior to the signal corresponding to the staining of one cell being known as not expressing said marker. The skilled person is well aware of how to identify said cells / markers so that these protocols do not need to be detailed here.

The results disclosed in the experimental part of the present application show that the cell culture obtained by the method of the invention is capable of inducing angiogenesis in vitro and in vivo. These results moreover show that administering said cells to individuals (human or animal subjects) suffering from an ischemic disease or from a disorder of the circulatory system results in a detectable improvement of one or more symptoms of said disease or disorder.

The results disclosed below also show that the methods of the invention enable to generate cells expressing high level of the CD106 / VCAM1 membrane protein. Importantly, this protein has been recently associated to the expression of pro-angiogenic cytokines. Therefore, CD 106+ MSCs have been selected for their pro-angiogenic efficiency, and proposed as a treatment for hindlimb ischemia ([16], [17]).

Therefore, in a third aspect, invention relates to the use of said cells as a medicament for treating an individual suffering from an ischemic disease or from a disorder of the circulatory system. In other words, the invention relates to the use of said cells for the manufacture of a medicament intended to be used for treating subjects suffering from an ischemic disease or from a disorder of the circulatory system. The medicament of the invention can also be applied to skin vascular capillary network and may include dermatological and cosmetic applications.

Any mammal may be treated by the cells of the invention. Said mammal can be a pet (a dog, a cat, a horse, etc.) or a cattle animal (a sheep, a goat, a cow, etc.). It is obvious for the skilled person that, when an animal is to be treated according to the method of the invention, the initial undifferentiated MSCs will be obtained from a biological sample from the same animal species (allogenic graft) or from a similar species (heterologous graft), and the growth factors that are used in the second culture medium will correspond to those of the same animal species. For example, if a cat is to be treated, then the initial MSCs will be obtained from a perinatal tissue or biological fluid of a cat, and a cat I L1 β (recombinant or not) will be added in the second culture medium, optionally along with cat IL4.

In a preferred embodiment, said mammal is a human being. In this case, the initial MSCs will be obtained from a perinatal tissue or from a biological fluid obtained from a woman, and human IL1 β (recombinant or not, e.g., SEQ ID NO:6) will be added to the second culture medium, optionally along with human IL4 (e.g., of SEQ ID NO:7). In this aim, the cell culture of the invention may be transplanted or topically applied to said subject by any conventional means. In this case, the present invention is drawn to a method for treating a subject suffering from an ischemic disease, a disorder of the circulatory system, an immune disease, an organ injury or an organ function failure, said method comprising the step of transplanting the cell culture described above to said subject. This transplantation may be performed by using an implanted reservoir or by injecting the cells in situ in the muscle, or via intravenous injections or by any appropriate delivery system. The application may also be performed topically, by directly contacting the cells with skin or a mucous membrane, or by applying the cells with a device on the skin or on any mucous membrane, or by delivering the cells by any appropriate delivery system to the skin or mucous membrane.

Preferably, said disease or disorder is chosen in the group consisting of: type-1 diabetes mellitus, type-ll diabetes, GVHD, aplastic anemia, multiple sclerosis, Duchenne muscular dystrophy, rheumatoid arthritis, cerebral stroke, idiopathic pulmonary fibrosis, dilated cardiomyopathy, osteoarthritis, cirrhosis, liver failure, kidney failure, peripheral arterial occlusive disease, critical limb ischemia, peripheral vascular disease, heart failure, diabetic ulcer or any degenerative disease, synechia, endometrial disorder or fibrotic disorder of the gastro-intestinal tract such as anal fistula.. More preferably, said disease or disorder is a peripheral arterial occlusive disease, a critical limb ischemia, a peripheral vascular disease, or a diabetic ulcer. In a particular embodiment, said disease or disorder is a skin or a mucous membrane disease, including (but not limited to) a diabetic ulcer, an ulcer, a trauma, a burn, a scald, a wound or a wound healing problem, Decubitus ulcer, a wart, etc.

The cell culture of the invention may more precisely be used in a dermatological preparation whose aim is to treat skin pathologies such as burns, wounds, ulcers, scars, warts, or other diseases such as synechia or fibrotic disorders of the gastro-intestinal tract (for example anal fistula). In another particular embodiment, said disease or disorder is anal fistula or endometrial injury.

Other applications are encompassed within the present application. In particular, it is possible to use the MSCs of the invention for dermatologic or cosmetic purposes, for example for regenerating the cells of the skin or of a mucosal membrane, improving the aspect of the skin or of a mucosal membrane, correcting a defect of the skin or of a mucosal membrane or for healing burning area of the skin or of the mucosal membrane.

In order to enhance the efficiency and facilitate the administration of the medicament of the invention, the cell culture of the invention may be mixed with any agent, composition of agents or other biologically compatible material or device. The cell culture of the invention may also be encapsulated or included in any appropriate delivery system or biocompatible material. The cells or preparation containing the cells may be applied with a medical device, such as a endoscope, a stent, or a syringe, for example. It can be also applied topically by contacting the cells with the skin or a mucosa. The present invention also targets a medical device containing the cell culture of the invention. By "medical device", it is herein encompassed any instrument, apparatus, implement, machine, appliance, implant, reagent for administering a therapeutic composition. In the context of the invention, said medical device is, for example, a patch, a stent, an endoscope, or a syringe. The present invention also targets a delivery system containing the cell culture of the invention. By "delivery system", it is herein encompassed any system (medium or carrier) for administering a pharmaceutical product to a patient. It can be an oral delivery or a controlled-release system. In the context of the invention, said delivery system is for example liposomes, proliposomes, microspheres, micro- or nano-vesicles of biopolymers, lipids or nanoparticles. In a preferred embodiment of the invention, the cells of the invention are included in an hydrogel or another biocompatible material or excipient. Said hydrogel may include notably alginate sodium hydrogel, hyaluronic acid hydrogel, chitosan hydrogel, collagen hydrogel, HPMC Hydrogel, Poly-L-lysine hydrogel, Poly-L-glutamic acid hydrogel, polyvinyl alcohol (PVA) hydrogel, polyacrylic acid hydrogel, polymethylacrylic acid hydrogel, polyacrylamide (PAM) hydrogel, and Poly N acrylamide (PNAM) hydrogel.

The present invention also relates to a hydrogel containing the MSCs of the invention and possibly another biocompatible material or excipient. An alginate hydrogel is herein preferred, such as for the alginate hydrogel described in CN106538515. In the context of the present invention, "biocompatible materials" are those classically used in biomedical applications. They are for example metals (such as stainless steel, cobalt alloys, titanium alloys), ceramics (aluminium oxide, zirconia, calcium phosphates), polymers (silicones, poly(ethylene), polyvinyl chloride), polyurethanes, polylactides) or natural polymers (alginate, collagen, gelatin, elastin, etc.). These materials may be synthetic or natural. Biocompatible excipients are well-known in the art and do therefore not need to be detailed.

This hydrogel can be used for cosmetic or therapeutic purposes.

The present invention also concerns a pharmaceutical or a veterinary composition containing the cell culture of the invention, as well as its use for treating the diseases and disorders mentioned above. It also concerns a dermatologic or cosmetic composition containing the cell culture of the invention.

This pharmaceutical, veterinary or cosmetic composition may further contain other biocompatible agents (e.g., an hydrogel) as described above.

Said composition preferably contains at least about 1 to 5 x 10 ⁶ cells. DESCRIPTION OF THE FIGURES

In order that the disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments and illustrated figures. The figures together with a detailed description below serve to further illustrate the embodiments and explain various principles and advantages in accordance with the present disclosure.

Fig. 1 discloses a diagram showing how the CD106 ^high CD151 ⁺ Nestin ⁺ MSCs subpopulation of the invention can be prepared.

Fig. 2 shows the morphology of the MSCs attached to culture flasks in placenta, according to Example 1.

Fig. 3 shows the adipogenic and osteogenic cell differentiation of CD106 ^high CD151 ⁺ Nestin ⁺ MSCs. The results show that CD106 ^high CD151 ⁺ Nestin ⁺ MSCs subpopulation are capable of adipogenic and osteogenic differentiation in appropriate medium. The white arrows highlight lipid droplets and strongly mineralized area.

Fig. 4 shows a pathological examination by angiography: Representative angiograms obtained on postoperative day 21 .

Fig. 5 shows a pathological examination by LDPI: Representative LDPI images obtained on postoperative day 0 and day 21. On the above panel, the area is still affected 3 weeks after the transplant, as shown by the white arrow. On the lower panels, black arrows highlight perfused area, 3 weeks after the transplant.

Fig. 6 shows the results of placenta derived MSCs infusion for patients with diabetes. A total of 15 patients with diabetes (11 men and 4 women) were included in this clinical trial. (A) shows a reduction in mean insulin requirement after 3 times of treatment with perinatal tissue derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs in this group of 15 patients, which was statistically significant (P<0.001 ). (B) shows that the treatment of perinatal derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs also significantly improved the level of glycosylated hemoglobin of patients with diabetes (P<0.001 ). These results show that perinatal derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs may be a good choice for patients with diabetes.

Fig 7. (A) show the ascites level using ultrasonic examination before CD106 ^high CD151 ⁺ Nestin ⁺ MSCs infusion in a patient suffering from decompensated cirrhosis. And (B) show the ascites level using ultrasonic examination one month after the CD106 ^high CD151 ⁺ Nestin ⁺ MSCs were administered. (C) show that the liver functions of said patient improved significantly. CA125 expression decreased to normal level. In addition, total protein, albumin, globulin in serum also increased significantly.

Fig 8 shows the evaluation of the perfusion rate in a NOD/SCID mouse hindlimb ischemia model after arterial ligation and injection of various doses of umbilical cord MSCs of the invention, or saline solution or VEGF.

EXAMPLES For simplicity and illustrative purposes, the present invention is described by referring to exemplary embodiments thereof. It will be apparent, however, to one of ordinary skill in the art that the present invention may be practiced without limitation to these specific details. In other instances, well known methods have not been described in detail so as not to unnecessarily obscure the present invention.

1. Method to obtain the MSCs of the invention from placental tissue

The method of the invention has been realized by:

a) separately collecting human placenta tissue from multiple mother donors;

b) washing the placenta tissue three times using 1 X PBS, dissected in 1 mm ³ cubes and washing the cubes tissue again to remove most of the blood from the tissue.

c) digesting the placenta tissue of each donor separately with collagenase, centrifuging the digested tissue and collecting the mononuclear cells, d) seeding the mononuclear cells into a culture medium;

e) trypsinizing and passage the cells once they reach 85-90% confluence;

f) characterizing the cells based on the percentage of cells which express positive markers CD73, CD90, CD105 and CD166, and negative markers CD45, CD34 and HLA-DR;

g) seeding the cells in a culture medium containing 90% Dulbecco's Modified Eagle's Medium/F12-Knockout (DMEM/F12-KO) and 10% FBS and growth factors at a seeding density of 1000 to 5000 MSCs per cm ² when they comprise at least 95% of the positive markers and at most 2% of the negative markers,

h) obtaining CD106 ^high CD151 ⁺ Nestin ⁺ MSCs comprising over 80% cells which express CD106, 98% for CD151 , 98% for Nestin, and 95% cells which express positive markers CD73, CD90, CD

105 and CD 166, and less than 2% cells which express negative markers CD45, CD34 and HLA-DR (for transplantation use) and adding 20ng/ml_ of I L1 β (provided by Peprotech) and 20ng/ml_ of IL4 (provided by Peprotech) when they are 40-50% confluent;

i) trypsinizing and collecting the cells once they reach 90-95% confluence;

j) characterizing the cells based on the percentage of cells which express positive markers CD73, CD90, CD105 and CD166, and negative markers CD45, CD34 and HLA-DR.

This method enabled to generate a subpopulation of placental-derived MSCs with a yield of at least 1x10 ⁵ cells/cm ² MSCs (5x10 ⁶ MSCs in T75 cm ² flasks when they are 90% confluent) that can be used in allogenic administrations. These cell cultures comprised over 95% cells which express positive markers CD73, CD90, CD105 and CD166, and less than 2% cells which express negative markers CD45, CD34 and HLA-DR.

The human perinatal tissue derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs were fibroblast-like and grow very well on plastic flask (cf. Fig 2). Three independent experiments have been performed (experiment 1 , experiment 2 and experiment 3). 20ng/mL of both Interleukin 1 (β) and 4 have been added when the cells are 40-50% confluent (see Fig 1 ). At that point, MSCs comprise over 95% cells which express the positive markers CD73, CD90, CD105 and CD166, and less than 2% cells which express the negative markers CD45, CD34 and HLA-DR. After this, MSCs keep growing till 90% cell confluent (see Tables 1 and 2 below), in practice during about 2 days.

Of note, the expression of MSCs cell surface protein CD106, CD151 and Nestin increased significantly after the interleukin 1 and 4 were added.

TABLE 1 shows the expression of CD11 b, CD19, CD29, CD31 , CD34, CD45, CD73, CD90, CD 105, CD106, CD151 , Nestin and HLA-DR on placenta tissue derived MSCs before adding interleukin 1 and 4 obtained in placenta Example 1 , 2, and 3. These results show that placenta derived MSCs have classical cellular surface markers just like bone marrow and adipose tissue derived MSCs.

Surface markers Experiment 1 Experiment 2 Experiment 3

IgG-PE 0.4% 0.9% 0.1 %

IgG-FITC 0.5% 0.1 % 0.4%

CD11 b-PE 0.2% 1.4% 0.3%

CD19-FITC 0.7% 0.2% 0.6%

CD34-FITC 0.9% 0.1 % 0.3%

CD45-PE 0.2% 1.1 % 0.3%

CD31 -FITC 0.3% 0.1 % 0.4%

CD73-PE 99.2% 99.1 % 99.8%

CD90-PE 99.7% 100% 98.9%

CD105-FITC 96.7% 98.1 % 98.8%

CD106-PE 31.5% 23.2% 30.6%

CD151 -PE 95.6% 96.1 % 93.8%

CD29-PE 99.4% 100% 99.9% CD44-FITC 99.6% 99.4% 99.2%

Nestin-PE 82.5% 78.7% 84.1 %

HLA-DR-PE 0.0% 0.9% 0.0%

Table 1

TABLE 2 shows the expression of CD11 b, CD19, CD29, CD31 , CD34, CD45, CD73, CD90, CD 105, CD106, CD151 , Nestin and HLA-DR on the placenta tissue derived MSCs after adding interleukin 1 and 4 in Experiments 1 , 2 and 3. The results show that CD106 and Nestin protein marker increased significantly 48 hours after adding the IL-1 and IL-4 in complete medium. Meanwhile, the CD106 ^high CD151 ⁺ Nestin ⁺ cells still have classical MSCs cellular surface phenotypic marker.

Surface markers Experiment 1 Experiment 2 Experiment 3

IgG-PE 0.1 % 0.6% 0.2%

IgG-FITC 0.2% 0.4% 0.4%

CD11 b-PE 0.2% 1.0% 0.1 %

CD19-FITC 0.4% 0.8% 0.8%

CD34-FITC 0.4% 0.2% 0.5%

CD45-PE 0.5% 0.8% 0.7%

CD31 -FITC 0.7% 0.5% 0.8%

CD73-PE 99.9% 99.9% 99.7%

CD90-PE 99.3% 100% 99.7%

CD105-FITC 99.8% 99.8% 95.5%

CD106-PE 82.7% 81.9% 84.3%

CD151 -PE 98.2% 99.4% 98.3%

CD29-PE 100% 100% 99.6% CD44-FITC 99.8% 99.8% 99.6%

Nestin-PE 93.7% 92.9% 90.6%

HLA-DR-PE 0.0% 1.3% 0.5%

Table 2

These subpopulations can secrete more cellular growth factors, cytokines, immunomodulation factors and inflammation factors (see Table 3). These CD106 ^high CD151 ⁺ Nestin ⁺ MSCs will therefore have a better potential of immunomodulation and angiogenesis.

Table 3 shows the related expression levels of growth factors secreted in the spent media by q-PCR. The results show that placenta tissue derived MSCs have more protein expression or secretion of IL-6, IL-8, IL-10, HGF, ANG, MMP2, VEGF-A and TGF- at 48 hours after adding IL-1 and IL-4 in complete medium.

Table 3 2. Method to obtain the MSCs of the invention from umbilical cord tissues

The following reagents have been used in the present example:

2.1. Cell isolation by explant method The umbilical cord was removed from the transport solution and cut in 2-3cm long sections.

To avoid contamination by adherent blood cells, each cord segment containing a blood clot that cannot be removed was discarded. The sections were then disinfected in a bath of antibiotics and antifungal agents composed of aMEM + Vancomycin 1 g/L + Amoxicillin 1 g/L + Amikacin 500 mg/L + Amphotericin B 50 mg/L for 30min at room temperature (RT). Antibiotics were extemporaneously dissolved in sterile water for injection.

The sections of umbilical cord were removed from the bath and quickly rinsed in 1X PBS at RT. The epithelial membrane was slightly sectioned without touching the vessels. Each section was then detailed in slices of 0.5cm thickness and disposed at the bottom of a 150cm ² plastic flask with lid. 6 to 10 slices per flask were disposed with at least a 1 cm radius circle of free space around each slice, and left to adhere for 15min without medium at RT.

After adhesion, complete medium (aMEM + 5% CPL + 2 U/mL heparin) was added carefully, to keep the explants adherent to the bottom of the flask. The flasks were then incubated at 37°C, 90% humidity and 5% C02. The culture medium was changed after 5 to 7 days.

At day 10 after isolation, the migration of the cells out of the explants was controlled by inverted microscopy. If a circle of adherent cells was visible around most of the explants, they were carefully removed, by picking them out of the flask, through the lid, with a sterile, disposable, single-use pair of tweezers. From this step, the confluency of the cells was visually checked every other day and, if needed, a medium change was performed at day 17.

When the cells reached 70-90% confluency or at D20, the medium was removed and cells were washed with 30ml_ of 1X PBS per flask. Cells were then removed with Trypzean® and collected with the old medium and centrifuged 10 min at 2500rpm. Supernatant was discarded and cells were then suspended in a cryopreservation solution consisting in aMEM + 100mg/ml_ HSA + 10% DMSO and cryopreserved.

2.2. Cell isolation by enzymatic method

The umbilical cord was removed from the transport solution and cut in 2-3cm long sections. To avoid contamination by adherent blood cells, each segment containing a blood clot that cannot be removed was discarded,. The sections were then disinfected in a bath of antibiotics and antifungal agents composed of aDMEM + Vancomycin 1 g/L + Amoxicillin 1 g/L + Amikacin 500 mg/L + Amphotericin B 50 mg/L for 30min at room temperature (RT). Antibiotics were extemporaneously dissolved in sterile water for injection. The cord was then cut in small pieces and immersed in an enzymatic cocktail comprising 2.7 mg/mL collagenase type I and 0.7 mg/mL hyaluronidase, incubated for 3 h at 37°C with gentle agitation, followed by the addition of 2.5% trypsin and a further incubation for 30 min.

The digested suspension was diluted 1 :2 with medium to reduce the viscosity of the suspension and passed through a nylon mesh to obtain single suspension. Cells were centrifuged at 300 x g for 20 min, and seeded at 10,000 cells/cm ² with fresh medium.

The culture medium was changed after 5 to 7 days and every 7 days after that.

When the cells reached 70-90% confluency or at D20, the medium was removed and cells were washed with 30ml_ of 1X PBS per flask. Cells were then removed with Trypzean® and collected with the old medium and centrifuged 10 min at 2500rpm. Supernatant was discarded and cells were then suspended in a cryopreservation solution consisting in aMEM + 100mg/ml_ HSA + 10% DMSO and cryopreserved.

2.3. Cell thawing and culture Cells were thawed following a classical protocol. Briefly, cryotubes were removed for liquid nitrogen and quickly plunge into a 37°C water bath. As soon as there was no ice left in the tube, cells were diluted in preheated (37°C) complete medium (aMEM + 0.5%(v/v) ciprofloxacine + 2U/ml_ heparin + 5% (v/v) LP) and quickly centrifuged (300g, RT, 5min).

After centrifugation, the cells were suspended in preheated complete medium, and assessed for number and viability (blue trypan / Mallassez hemocytometer).

The cells were seeded in two 75cm ² plastic culture flasks in complete medium, and incubated (90% humidity, 5% C0 ₂ , 37°C). 2.4. Cell stimulation

After a few days of expansion, the cells were checked for confluency. When confluency reached 30 to 50%, the old medium was discarded and replaced either by fresh complete medium for unstimulated condition, or by fresh medium completed with 10ng/ml_ of I L-1 β and 10ng/ml_ of IL-4.

Cells were then incubated at least 2 days before the flow cytometry experiments.

2.5. Cell harvesting and flow cytometry analysis

After 2 to 3 days of expansion/stimulation, the cells were checked for confluency. If confluency was up to 80%, the cells were harvested. Briefly, the old medium was discarded and the cells were washed with 1 X DPBS. Trypsin EDTA was added and the cells were incubated 5 min at 37°C. Trypsin was neutralized with at least 2X the volume of medium, and the cell suspension was harvested and assessed for number and viability.

The flow cytometry experiment required 1x10 ⁶ cells, which were centrifuged and resuspended in 1 X DPBS + 0.4% HSA.

The cells were labelled for CD73, CD90 CD105, CD106, CD151 and CD31 , CD34, CD45, HLA-DR according to the following protocol:

1. The cells were assessed for viability and number.

2. The volume of suspension necessary to obtain 20 000 cells /labelling tube was placed in a 15ml_ propylene plastic tube.

3. The tube was centrifuged 5min at 300g and 4°C.

4. The cells were resuspended with 1X DPBS + 0.4% HSA (dilute 10x 4mg/ml_ HSA in 1XDPBS). The volume necessary was 500μΙ_ per labelling tube. Extracellular staining was performed for CD106 and CD151 markers as recommended by the FACS manufacturer and antibodies providers. Intracellular staining was performed for Nestin. For intracellular staining, the Fixation/Permeabilization solution called "BD Cytofix/Cytoperm kit" was used. If the cells were not analyzed immediately after the staining, a fixation step was performed, by contacting the cells with a 1XDPBS 0,5% formaldehyde solution.

After labelling, the cells were washed with 1X DPBS + 0.4% HSA and permeabilized for Nestin labelling.

The labelled cells were analyzed with the Accuri C6+ BD Biosciences cytometer, and results were analyzed with the BD Accuri C6 Plus software.

2.6. Results

Several batches of umbilical cord-derived MSCs (HB-COR001 to COR005-MSC) have been obtained by cultivating cord-MSCs isolated by means of the explant methods disclosed above (2.1.) in the conditions exposed in point 2.4. above. For Cord 3 and 5 (COR003 and COR005), two MSC populations (MSC1 and MSC2) have been obtained concomitantly, by repeating the steps of the invention in a separate manner.

The expression of CD 106 at the surface of said cells was measured by flow cytometry.

All tested batches of MSC exhibited a drastic increase (>60%) in the CD106 expression levels (see table 4). CD106 levels before and after full stimulation (lOng/mL of BOTH IL-lb and IL-4)

% of CD106 % of CD106

Cord

before stimulation after stimulation Umbilical Cord-derived MSC

HB1-COR001-MSC1 15,71% 97,34%

HB1-COR002-MSC1 9,58% 70,62%

HB1-COR003-MSC1 8,25% 69,42%

HB1-COR003-MSC2 8,25% 59,47%

HB1-COR005-MSC1 9,89% 71,26%

HB1-COR005-MSC2 9,89% 75,48%

Table 4: CD106 expression of Umbilical Cord-derived MSCs after stimulation with I L1 β and IL4

3. Impact of the isolation protocol on CD106 expression of umbilical cord-derived MSCs Mesenchymal stem cells were isolated from umbilical cord using the two different methods exposed above (see 2.1. and 2.2.) : by explant isolation and by enzymatic digestion.

All cells were cultivated in the same culture medium (aMEM + 5% platelet lysate (LP)), stimulated at passage 3 according to the method of the invention and collected 2 days after stimulation. Cells viability is measured and cells were counted. The expression of several phenotypic markers, including CD106, was then measured by flow cytometry.

All MSCs, whatever the isolation method or the stimulation condition, expressed phenotypic markers in a classical way : CD73, CD90, CD105 are over 95% positive, while CD31 , CD34, CD45 and HLA-DR were negative. CD151 + and Nestin were also both over 95% positive, independently of the stimulation or the isolation method.

Without stimulation, the MSCs isolated by enzymatic digestion expressed higher levels of CD106 before stimulation (53%) than the MSCs isolated with the explants methods (20%) They were however less sensitive to stimulation with the inflammatory cocktail: a smaller increase in CD 106 has been observed ( +4% increase vs +60% increase).

The explants method is therefore the preferred method of the invention for umbilical cord-derived MSCs.

Table 5: viability and cell count of the MSCs obtained after the two experimental protocols exposed in 2.1 . and 2.2.

Table 6: molecular markers of umbilical cord-derived MSCs obtained by the two experimental conditions exposed in 2.1 . and 2.2. 4. Effects of stimulation with an IL1 -IL4 combination versus IL1 or IL4 alone stimulation on CD106 levels of umbilical cord mesenchymal stem cells

Mesenchymal stem cells were isolated from two umbilical cord by explant isolation (see 2.1 .).

All cells were cultivated in the same culture medium (aMEM + 5% platelet lysate (LP)), stimulated at passage 4 according to the method of the invention with a mix of 10ng/ml_ of IL-1 b and 10ng/ml_ of IL-4, or by each interleukin separately (10ng/mL each) and collected 2 days after stimulation. Cells viability is measured and cells were counted.

The expression of several phenotypic markers, including CD106, was then measured by flow cytometry. All MSCs, regardless of the stimulation condition, expressed phenotypic markers in a classical way: CD73, CD90, CD105 are over 95% positive, while CD31 , CD34, CD45 and HLA-DR were negative. CD151 + was also over 95% positive, independently of the stimulation.

Regarding the CD106 marker, the increase of expression observed with the stimulation with a combination of IL1 and IL4 is 3 to 5-fold higher than the increase of expression observed with a single interleukin stimulation (see Table 7.).

Table 7: CD106 expression levels obtained after stimulation of MSCs with a combination of

IL1-IL4 or with a single IL. 5. Neovascularization effect of placental derived CD106 ^high CD15T Nestin ⁺ MSCs in diabetic rats

This example focuses on the therapeutic neovascularization effect of placental derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs. It provides insights into their potential for clinical use as a cell-based therapy combined with insulin injection for treating critical hind limb ischemia in diabetes. Our results showed that Placenta derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs participate in angiogenesis and therapeutic vascularisation in order to improve ischemia and restore blood flow perfusion by directly differentiating into vascular cells. In addition, placenta derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs improved ischemia damage and functional recovery in diabetic rats.

Immunodeficient male nude rats of six weeks of age were purchased from Vital River Laboratories (Charles River Laboratories suppler in China). Diabetes was induced with a single intraperitoneal injection of streptozotocin (70 mg/kg in Citrate buffer solution, only prepared immediately prior to injection) after overnight fasting. Fasting plasma glucose levels were measured every week and rats with Plasma glucose between 11 mM and 15 mM were considered to be diabetic. Age- and weight-matched nude rats receiving an intraperitoneal citrate buffer injection were used as non-diabetic controls (glycaemia between 5.5 and 8 mM).

Two weeks later, diabetic nude rats were anesthetized (60mg/kg pentobarbital intraperitoneally) and the left femoral artery were occluded by ligating it with 3-0 silk. The ligature was applied 0.5 cm proximally to the bifurcation of the saphenous and popliteal arteries. Lipiodol (1.5ml/kg) was used to induce an embolism intravascularly. A sham ligature was applied to the left femoral artery with the left hind limb remaining non ischemic.

After the ischemia model was established, the surgical limb deficiency was obvious as the limb could no longer support any weight and the paw was swollen and red. Over time the ischemic damage improved to different degrees in all the groups. The recovery of limb function was significantly increased in CD106 ^high CD151 ⁺ Nestin ⁺ MSCs subpopulation (figure 4).

More precisely, the histological data on figure 4 show that the capillary density was increased in the cell transplant groups compared to the PBS group. In addition, more capillary numbers were observed in the CD106 ^high CD151 ⁺ Nestin ⁺ MSCs subpopulation cell transplant groups in diabetic rats and non-diabetic rats in comparison with the PBS group.

Figure 5 showed the functional evidence of ischemia-induced changes using vascularisation LDPI. The image shows that blood flow was completely blocked in the left hind limb on the surgical day; this is indicated by the deep dark colour. Three weeks later, the blood flow perfusion was restored to some degree in all the groups but did not return to normal in the PBS group where the ischemia/non-ischemia perfusion ratio only achieved 52%. The perfusion recovery in the cell transplant groups was significantly higher. The ratio was 81 % in the P- MSCs group of the prior art (P<0.05 vs PBS group) and 86% for the CD106 ^high CD151 ⁺ Nestin ⁺ MSCs subpopulation group (P<0.01 vs PBS group).

The perfusion recovery in both MSCs subpopulation was significantly higher. Therefore, the results revealed that MSCs improve blood flow perfusion and that the MSCs of the invention are more effective in doing so. In fact, the MSCs of the invention showed a significant improvement in the restoration of blood flow in both diabetic and non-diabetic rats.

The results revealed that the MSCs of the invention improve blood flow perfusion more efficiently than the MSCs of the prior art. This example indicates that administration of the MSCs of the invention is a promising new approach for diabetic critical limb ischemia. 6. Therapeutic effect of placenta derived CD106 ^high CD15T Nestin ⁺ MSCs of the invention to patients with diabetes

This example focuses on the therapeutic effect of placenta derived CD106 ^high CD151 ⁺ Nestin ⁺ MSCs of the invention to patients suffering from diabetes. It provides insights into their potential for a clinical use as a cell-based therapy diabetes.

A total of 15 patients with diabetes (11 men and 4 women) were included in this clinical trial. The inclusion criteria were patients with type 2 diabetes diagnosed from November 2013 to November 2014 in Tianjin General Hospital. The patients were between 30 and 85 years of age, duration of diabetes>3 years, requiring insulin for optimal glycemic control in a dose of >0.7 U/kg/day at least for 1.5 year, having insulin dysfunction, poorly controlled blood glucose fluctuation with insulin-based treatment, and willingness to participate in the study. These 15 patients were between 42 and 67 years of age, with a median age of 59 years old; duration of diabetes from 3 years to 17 years, with an median of 8 years; daily insulin requirement from 38 units to 90 units, with an average of 58.7 units. Simultaneous glucose tolerance test, insulin release test, C peptide stimulation test and the determination of glycosylated hemoglobin was examined every three months. The cardiac, liver and kidney function tests were performed. The adverse events and side effects were observed during treatment. It was considered it to be effective if daily insulin requirement reduced by>50% after treatment and lasted more than 3 months.

The patients received three intravenous infusions of the placenta derived MSCs (P-MSCs) of the invention, with one month interval of infusion. The total number of P-MSCs administered for each patient was of (1.0-1.5)* 10 ⁶ / kg, with an average of 1.25 * 10 ⁶ /kg. At the same time, patients continued to apply insulin, and adjusted the insulin dose according to blood glucose levels. For complications, the original general treatments were maintained. All of the patients were followed up after therapy for at least 6 months. This clinical trial showed a reduction in mean insulin requirement after 3 administrations of placenta derived MSCs of the invention in this group of 15 patients, which was statistically significant (P<0.001 ). The insulin injection dosage for patients with diabetes almost decreased by half after Placenta-derived MSCs of the invention were administered (as compared with the mean insulin dosage taken during the 6 months prior to MSCs administration) (Fig.6 A).

This clinical trial showed that the treatment with placenta derived MSCs of the invention significantly decreased the level of glycosylated hemoglobin of patients with diabetes (P<0.001 ) (Fig. 6B).

These data support that the MSCs of the invention can be used for treatment of patients with diabetes.

7. Therapeutic effect of the placenta derived MSCs of the invention to patients with aplastic anemia

This example focuses on the therapeutic effect of placenta derived MSCs of the invention to patients with aplastic anemia and provides insights into their potential for clinical use as a cell-based therapy for aplastic anemia.

Aplastic anemia is mostly considered as an immune-mediated bone marrow (BM) failure syndrome, characterized by hypoplasia and pancytopenia with fatty BM and reduced angiogenesis. Previous investigations have demonstrated that acquired aplastic anemia is manifested by abnormalities of HSCs/HPCs and hematopoietic microenvironment. Lots of evidences have hinted that aplastic anemia might be a syndrome characterized by stem/progenitor-cell disorders including HSCs/HPCs and MSCs. MSCs support hematopoiesis and regulate almost overall immune cells function to maintain the hematopoietic and immune homeostasis. MSCs can modulate the functions of the main immune cell including T cells, B cells, monocytes, DCs, NKTs and neutrophils [5]. MSCs possess remarkable immunosuppressive properties on Th1 , Th17 and CTLs. MSCs inhibit the proliferation of T cells, IFN-γ and TNF-a secretion by Th1 cells while promoting IL-10 production by Th2 cells and the expansion of Treg cells. However, recent researches showed that MSCs from aplastic anemia patients had poor proliferation and deficient immune suppression of MLR, PHA-induced T cell activation and IFN-γ release [6,7]. Our recent study showed that MSCs from aplastic anemia patients were reduced in suppressing the proliferation and clonogenic potential of CD4+ T cells while promoting Treg cells expansion. MSCs were also found defective in suppressing the production of TNF-a and IFN-γ by CD4+ cells. However, there was no significant difference in regulating the production of IL-4, IL-10 and IL-17 [8]. In addition, our research also showed that MSCs from aplastic anemia patients showed aberrant morphology, decreased proliferation and clonogenic potential, and increased apoptosis as compared with BM-MSCs from healthy controls. MSCs from aplastic anemia patients were susceptible to be induced to differentiate into adipocytes but more difficult to differentiate into osteoblasts. Consistent with abnormal biological features, a large number of genes implicated in cell cycle, cell division, proliferation, chemotaxis and hematopoietic cell lineage showed markedly decreased expression in MSCs from these aplastic anemia patients. Conversely, more genes related with apoptosis, adipogenesis and immune response showed increased expression in MSCs from aplastic anemia patients. The gene expression profile of MSCs further confirmed the abnormal biological properties and provided significant evidence for the possible mechanism of the destruction of the BM microenvironment in aplastic anemia [9].

MSCs is a promising therapeutic candidate for treating aplastic anemia due to the following two important facts:

i) the hematopoiesis supportive and potent immunosuppressive capability of MSCs in general and

ii) the biological characteristic difference and functional deficiency observed in MSCs derived from patients with aplastic anemia. In a clinical trial, a 6-year-old girl with intermittent fever continued for more than a month was treated with MSCs. Aplastic anemia was confirmed after two bone marrow biopsies revealed hypocellularity. There was no improvement in the peripheral blood phenotype after treatment of cyclosporine and stanozolol for almost 6 months. Hematopoietic stem cell transplantation was not good choice because it was very difficult to find a matched donor. Therefore, the patient was administered by intravenous infusion with 1 x 10 ⁷ of the placenta derived MSCs of the invention. The peripheral blood phenotype improved significantly after the 1 ^st MSCs transplantation. However, the patient was still dependent on blood products transfusion including red blood cell and platelet transfusion. 6 months later, the patient accepted for the 2 ^nd time a 1 * 10 ⁷ intravenous injection of the MSCs of the invention. The phenotype of peripheral blood improved significantly and reached almost normal levels 12 months after the 2 ^nd injection. In addition, the patient was completely independent on blood products transfusion 12 months after the 2 ^nd injection (Table 8). These data support that the placenta derived MSCs of the invention can be used for clinical treatment of patients with aplastic anemia.

Phenotype of PB Pre-treatment 6 months post 12 months post

1 ^st MSCT 2 ^nd MSCT

WBC 0.64x 10 ⁹ /l 4x 10 ⁹ /l 5x 10 ⁹ /l

ANC 0.03x 10 ⁹ /l 1 10 ⁹ /l 1 .5x 10 ⁹ /l

HGB 48 g/l 80 g/l 110 g/l

PLT 3x 10 ⁹ /l 28x 10 ⁹ /l 53x 10 ⁹ /l

Table 8

The phenotype of peripheral blood during the treatment of placenta derived MSCs. 8. Therapeutic effect of the placenta derived MSCs of the invention to patients with liver diseases

This example focuses on the therapeutic effect of placenta derived MSCs obtained according to the method of the invention (i.e., with IL1 and IL4 treatment) administered to patients suffering from liver diseases. It provides insights into their potential for clinical use as a cell-based therapy for liver diseases.

In this clinical trial, a 40- year-old man was confirmed suffering from alcoholic hepatitis for more than ten years. The patient was confirmed with decompensated cirrhosis two years ago although he accepted conventional treatment. Because there is no good choice for treatment of decompensated cirrhosis, the patient accepted voluntarily an intravenous injection of 4*10 ⁷ MSCs of the invention.

In this clinical trial, the ultrasonic examination results showed an ascite level of 9.7 cm before MSCs were administered (see Fig. 7A). However, the ascite level decreased to 3.6 cm one month after the administration of the MSCs (Fig.7 B). Furthermore, the results showed that the liver functions of patient with decompensated cirrhosis improved significantly after the administration of the MSCs. Moreover, CA125 expression in serum decreased to normal level according to the clinical references. These results demonstrate the excellent clinical reaction in decompensated cirrhosis patients treated with the MSCs of the invention.

In addition, total protein, albumin, globulin in serum also increased significantly to reach the normal level according the clinical references (Fig.7 C). These results showed that patient's liver synthetic and metabolic function improved one month after the intravenous injection of MSCs.

Therefore, the placenta derived MSCs of the invention is a very good cytotherapeutic choice for liver diseases. 9. Angiogenic potential of the cells of the invention, obtained from umbilical cord

The pro-angiogenic potential of the MSC of the invention has been further tested in a hindlimb ischemia murine model.

Material & methods

Twelve 8-week-old NOD/SCID mice (Laboratoire Janvier) were anesthetized with a mix of ketamin and xylazine. The left proximal and distal parts of the femoral artery of the left leg was then ligated (6.0 silk suture, Ethicon, Issy-Les-Moulineaux, France) and the part between ligations excised. Mice that exhibit more than 80% of ischemia after surgery were intramuscularly injected in the gastrocnemius muscle of the ischemic limb with 2 doses of MSCs of the invention as obtained according to the protocols exposed in point 2.4. above (0.5x10 ⁶ cells per animal in Group 2, 0.05. 10 ⁶ cells per animal in Group 3). A saline solution injection was used in the Control Group 1. A dose of 20ng/ml_ of VEGF/mice was also injected in the Control Group 4.

The injection scheme as well as the dose was derived for the intended clinical use of the cells and the dose administered to animals was >10 times the proposed dose for a phase l/ll clinical trial in humans (which is of about 25x10 ⁶ cells/kg, that means about 0.5x10 ⁶ cells/mouse (average mouse weight = 20 gr)).

Hind limb blood flow was measured using a scanner-laser Doppler (Laser Doppler Perfusion system, Perimed PeriScan PIM III). The average perfusion of ischemic and non-ischemic limbs was determined before and after ischemia, and every 7 days until 21 days after ischemia. Blood flow-dependent changes in laser frequency were imaged using different colored pixels. Images were analyzed to quantify blood flow by using a blood perfusion analysis software (LPDIwin). Percentage of perfusion was expressed as the ratio of the ischemic to the non-ischemic hind limb. Hematoxylin-Eosin staining of hind limb muscle sections

Mice were euthanized at the end of the experiment (D21 ). Hind-limb gastrocnemius muscles were dissected and stained to visualize the distribution of the cells nuclei in the muscular fiber. Muscles isolated from the ischemic hind limb were fixed in paraffin and stained with hematoxylin/eosin.

Results

Figure 8 shows the mean reperfusion rate after hind limb ischemia in mice treated with different injections : NaCI 0,9% (negative control - n=8), VEGF 20 ng/ml (positive control - n=6), 50.10 ³ MS cells (n=9) and 500.10 ³ MS cells (n=7).

These results demonstrated that administration of high doses of the MSCs of the invention in mice after ligation of the femoral artery resulted in higher perfusion rates when compared to vehicle (NaCI) of VEGF administered alone. A 100% perfusion rate was observed as early as 7 days post cell injection for mice receiving the highest dose of cells (0.5x 10 ⁶ cells). There was a statistically significant difference with the other groups.

Also, a dose response effect is likely since in this preliminary experiment the highest dose of cells (0.5x 10 ⁶ cells) seems to achieve better perfusion rate than a 10 folds lower dose. These results confirm the actual angiogenic potency of the MSCs of the invention to improve blood perfusion in this mouse model of CLI.

Results observed in the hematoxylin-eosin staining (data not shown):

In the normal, non-ischemic muscles, cells nuclei are distributed in the periphery of the muscular fiber. In the ischemic muscles of mice from Groups 1 (NaCI 0,9%) and 4 (VEGF 20ng/ml_), 21 days after ischemia induction, cells exhibit very few nuclei in the periphery of the muscular fiber, since they are still regenerating.

In the ischemic muscles of mice from Group 3 (0.05. 10 ⁶ MSC cells or 50k), 21 days after ischemia induction, 50% of muscular fibers are regenerated and exhibit nuclei in the periphery of the fiber. The regeneration happens faster than in Groups 1 and 4.

In the ischemic muscles of mice from Group 2 (0.5*10 ⁶ MSC cells or 500k), 21 days after ischemia induction, 100% of muscular fibers are regenerated and exhibit nuclei in the periphery of the fiber. The staining profile of the muscle is identical to the normal, non-ischemic, muscle. In this experiment, the 500k cells dose allows a complete regeneration of the muscle.

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