Technical Field

The invention relates to nanofiber wound dressing comprising uridine or uridine derivatives for use in health industry.

Background of the Invention

Various medicines and wound dressings that can accelerate wound healing processes and can be used in current applications are available in the literature. These medicines or wound dressings, which are currently in use, are used daily or multiple times a day, have potential side effects due to the fact that most of them are synthetic chemical substances, as well as cause technical difficulties due to patient’s adaptation and complicating care conditions and also cause huge burden in economic terms. There is a need to develop new wound dressings with protective and rapid healing effects that can be used in the treatment of various wounds from an early period.

The documents identified upon patent and literature search made in the related art are summarised below.

European patent with publication number EP1835948 B1 relates to the production of a collagen-containing biomaterial to reduce calcification and prolong the life of the biomaterial. The document discloses process steps of exposure of the biomaterial containing collagen to an alcohol-containing solution for at least 24 hours, exposing the said material to a cross-linking agent, exposing the material to an acidic solution containing an amino-carboxylic acid capable of inactivating, and/or modifying fixed and unfixed cross-linking agent groups found in the material after the cross-linking step. The document discloses that the biomaterial can be a cultured tissue, a biomaterial isolated from an animal, cellular tissue of any kind (such as cardiovascular tissue, cardiac valve, aortic roots, aortic wall, aortic leaflets, pericardial tissue, connective tissue, dermal tissue, vascular tissue, cartilage, pericardium), an isolated collagen or synthetic polymer. In addition, it discloses that the biomaterial may also be composed of bio-absorbable materials such as polylactic acid, polyglycolic acid, polylactic acid- polyglycolic acid copolymers, polydioxanone, polycaprolactone (PCL), polypeptides, polycarbonates, polyhydroxybutyrate, poly(alkaline oxalate) etc. However, the said biomaterial is designed to be implanted inside the body. It is not a wound cover. The structure of the biomaterial does not consist of nanofibers. It does not disclose a substance that contributes to wound healing by being embedded into the implant material, nor does it show the release of this substance and follow-up of the release.

European patent EP2600910 B1 relates to wound dressings, devices, sealants, and adhesive agents that contain resorbable or non-resorbable materials and/or proteins, and coating of implantable devices, or adhesion of implantable devices to tissue. The document discloses that a non-toxic material in dry status is needed. For that reason, it discloses a cross-linkable protein and a non-toxic material inducing cross-linking of the protein. It discloses that the cross-linkable protein used herein may contain gelatine. However, the structure to be produced within the scope of this patent is not a nanofiber dressing, and there is no addition of a substance to the wound dressing structure that will contribute to wound healing, and there is no release control. Also, there is no use of biodegradable PCL polymer.

As a result, due to above-described disadvantages and inadequacy of existing solutions, it has been necessary to make development in the related art.

Brief Description of the Invention

The present invention relates to a nanofiber wound dressing meeting the needs mentioned above, eliminating all disadvantages, and providing some additional advantages.

The invention inspired from existing situations aims to solve the disadvantages described above.

Primary object of the invention is to disclose a nanofiber wound dressing comprising uridine for use in health industry.

Nanofiber structures create a suitable medium for wound healing with their high porosity, low pore sizes, large surface areas, and high mechanical strength. The surfaces can also be functionalized and allow production from a wide variety of polymers. With such advantages, they are superior to conventional wound dressings. The most important feature of the present invention is to obtain a nanofiber wound dressing from a biocompatible polymer by electro-spinning method and to add uridine, an endogenous compound which has no side effects even at high doses, to the nanofiber wound dressing with drug releasing property for a long-term and in a controlled and stable way. A wound dressing which releases drugs for a long-term and in a controlled and stable way prevents frequent change of dressings in patients, increases the wellness and comfort of the patients, and provides a rapid wound healing, while bringing less economic burden.

The use of biocompatible polymer in the composition of the invention and the addition of an endogenous molecule that can be produced in the body to the wound dressing due to its healing-accelerating feature provides superiority compared to the related art in preventing negative consequences that will affect human health compared to formulations with synthetic materials used in related art.

The wound dressing, which is the subject of the invention, is convenient for usage in accidental wounds in health industry, medical industry, post-operational wounds, wounds developing in association with electrical burns, wounds occurring after contact with chemicals, wounds associated with burns caused by contact with hot objects, wounds developed during diabetic diseases, pressure ulcers occurring in long-term lying patients.

The present invention, distinct from the known state of the art discloses production of a wound dressing comprising biocompatible nanofibers containing uridine to provide contribution to wound healing. In the present study although PCL is used as polymer, the characteristic of the invention is that any biocompatible polymer can be used. The present invention discloses addition of uridine into nanofiber structure to contribute to the healing of the wound, release of uridine onto wound, and the follow-up of uridine release and wound healing. In this respect, the present invention is different from the known state of the art in terms of material structure used therein, purpose of use and effectiveness thereof. Type of the polymer selected in the invention can be changed. Since uridine-added nanofiber surfaces generated by use of different polymer types and solvents will have varying surface features, polymer degradation rates and thus drug release profiles, drug release and effective dosage must be re-tested. In addition, release profile and release time of uridine may be altered by changing nanofiber surface construction (by forming multi-layer nanofiber surfaces, changing nanofiber structure with the addition of a porogen agent, forming shell/core nanofibrous structures etc.).

The method of the invention is based on the principle of exposing polymer solution/melt to an electrical field.

The wound dressing produced by the use of the method of the invention, can be used for incision wounds, post-surgical wounds, burn wounds, pressure sores, chronic wounds due to diabetes mellitus, and wounds seen in patients with immunodeficiency syndrome.

The structural and characteristic features of the invention and all advantages will be understood better in detail with the figures given below and with reference to the figures, and therefore, the assessment should be made taking into account with the given figures and detailed explanations given below.

Brief Description of the Drawings

Figure 1 presents a graph showing percent change in wound areas on a daily basis. (* denotes statistically significant difference of PCL+ 0.5% Uridine and PCL+ 1% Uridine surfaces compared with commercial product, # denotes statistically significant difference of PCL+ 0.5% Uridine and PCL+ 1% Uridine surfaces compared with No Additive PCL group (p<0.005)

Detailed Description of the Invention

In this detailed description, the preferred embodiments of the wound dressing have been described only for purpose of better understanding of the matter. The invention relates to nanofiber wound dressing for use in health industry. In the method for production of wound dressing of the invention, firstly polymer solution is prepared. The polymer used for the preparation of the polymer solution and the solvent specific to this polymer are used. In the next process step, nanofiber surface is produced from polymer solution by electrospinning method. At this stage, electrospinning device is used. Then uridine is added into the polymer solution.

The wound dressing which is the subject of the invention comprises preferably polycaprolactone (PCL) as polymer. In alternative applications of the invention, if another polymer is used instead of PCL, wound dressing can still perform its function. However, drug release profiles vary. In a preferred application of the invention, rate of PCL in solution is in range of 5-20%. However, it is likely to change PCL rates in alternative applications (i.e., 3-30%)

In the wound dressing of the invention, different solvents can be used to dissolve the polymer. Suitable solvents are selected depending on the polymer type. For PCL, DMF:DCM is used for this purpose. The solvent can be mixed in different ratios, in the range of 80-95% ratios in the total solution. Different solvents can be used in different ratios for different polymers.

Another component in the wound dressing of the invention is uridine. The uridine can be mixed in different ratios, in the range of 0.01-30% ratios in the total solution.

The term uridine derivatives comprise phosphate-bound uridine compounds, sugar- bound uridine compounds and uridine esters.

Phosphate-bound uridine compounds are another component of the invention. UDP (uridine diphosphate), UMP (uridine monophosphate) and UTP (uridine triphosphate)) can be used as phosphate uridine compounds. Within the scope of the invention it can be used in different ratios, in the range of 0.01-30% ratios in the total solution.

Within the scope of the invention sugar-bound uridine compounds are added in the range of 0.01 -30% ratios in the total solution. UDP-glucose, UDP-galactose are used as sugar-bound uridine compounds. The usage rate of uridine esters (ester-linked uridine compounds) used in the invention is in the range of 0.01% - 30% in the total solution, in the form of a mixture at different rates.

In a preferred application of the wound dressing production method of the invention, the polymer solution is prepared. The selected polymer is brought together with suitable solvents at certain concentrations, dissolution is achieved, and a polymer solution is obtained. Preferably PCL, a biodegradable polymer, is used. It is added into DMF and DCM, which are the solvents of PCL, in certain rates. However, use of PCL as polymers and DMF and DCM as solvents is not necessary and any biocompatible polymer treated with suitable solvents can be used. Then, with the help of a heated magnetic mixer, the polymer is completely dissolved in the solvents. The polymer solution is mixed on a heated magnetic mixer at 20-35 ^c C. After dissolving, uridine is added to the polymer solution at certain rates and the mixing process continues on the magnetic mixer until a homogeneous mixture is achieved. Then, the process of producing nanofibers from uridine-containing solutions by electrospinning method is applied. For this purpose, a certain amount of polymer is first taken into the syringe and placed on the feeding pump. With the help of auxiliary hoses and a feeding pump, the polymer solution containing uridine at a certain speed is fed to the spinning nozzle. A droplet is formed at the tip of the nozzle. Voltage is supplied to the formed droplet with the help of a high voltage source. When the critical voltage value is exceeded, the droplet starts to move towards the opposite collector. During the movement of the droplet between the nozzle and the collector, the solvents are removed, and the polymer jet elongates and becomes thinner and longer. When the droplet reaches to the collector, the nano-scaled dry fibers deposit on the collector. The purpose here is to obtain a surface consisting of fibers with diameters at the nanometer level. Parameters affecting the said method are as follows: solution properties (polymer concentration, viscosity, volatility of solvents, electrical properties of the solution, etc.), process parameters (feed rate, voltage, nozzle-to-collector distance, collector type and speed, nozzle/needle diameter etc.) and environmental parameters (temperature, humidity, pressure, atmosphere type, etc.). These parameters are effective on the diameter and morphology of the obtained nanofibers. The parameter ranges are preferably as follows:

• Supply rate 0,3-1 ,5 ml/h,

• Voltage: 5-25 kV,

• Distance between nozzle and collector: 5-25 cm,

• Nozzle diameter: 14-27 gauge,

• Collector type: Flat plate and rotary cylinder

• Speed of the rotating drum collector: 0-500 rpm,

• Production temperature, humidity, and atmosphere type: Daily medium conditions.

However, these parameters can be changed depending on the properties of the polymer and solvent.

PCL used in the invention is a biodegradable, biocompatible, non-toxic polymer. Its medical applications attract attention because of such features. Because of having long-term degradation times, it helps the long-term drug release, particularly in drug transport systems. With their high porosity and low pore sizes nanofiber structures both contribute to the breathing of the wound and help prevent the wound from infection. Such structures are advantageous when compared to conventional dressings due to their low diameter, high surface area, and high mechanical properties. In addition, it can be functionalized by adding various active substances into nanofiber structures. Thus, agents such as drugs etc. can be added into the structure. It also allows the production from many biodegradable or non-biodegradable polymers. Such features bring nanofiber structures to the forefront, particularly, in active ingredient-added wound dressing applications.

Because of activation of anti-oxidant systems by uridine, phosphate-bound uridine compounds (UDP (uridine diphosphate), UMP (uridine monophosphate) and UTP (uridine triphosphate)), sugar-bound compounds (UDP-glucose, UDP-galactose), or uridine esters anti-apoptotic properties, it can safely accelerate wound healing due to increasing the general regeneration of cells and tissues, and can be used in the treatment of all kinds of wounds and in accelerating the healing processes upon adding it into wound dressing its long-term, controlled and stable release thereof. In this description production of nano-fiber wound dressing including production of uridine-free and uridine-containing nano-fiber dressings by electrospinning method, characterization of the produced wound dressings (SEM, FTIR analysis, in vitro uridine release) and in vivo effectiveness of the produced wound dressings (demonstration of effectiveness in the wound model generated on experimental animals) are described.

To enable effectiveness of the wound dressing developed within the scope of the invention, percentage of wound reduction rate are studied.

Wound reduction % on given days:

Days Tegaderm No Additive PCL PCL + 0,5% PCL + 1% i (Positive Control) (negative control) Uridine Uridine

As seen in Figure 1 , wound healing in the groups using uridine-containing nanofiber dressings was faster and the wound closure rates were significantly higher than in the groups using commercial product and additive free PCL nanofiber surface.

The concentration of the polymer used in the invention, the solvent ratios, the amount of uridine added into the polymer solution is of particular importance. Such values must be determined meticulously in order to realize controlled and effective drug release.

Process parameters selected during nanofiber production (feeding speed, voltage, nozzle-collector distance, collector type and speed, nozzle/needle diameter etc.) affect nanofiber diameters and morphologies. For that reason, each of selected parameters must be ie compatible with one another and optimum.

Ambient conditions (temperature, humidity, pressure, atmosphere type, etc.) are effective for performance of a problem-free production. Since the production takes place in room conditions, the temperature and humidity of the daily environment can affect the production. PCL is a polymer that has been used in applications for a long time in the medical field. Although PCL is a polymer that can be used to produce nanofibrous dressings alone when it is considered that it can be added to the polymer solution of uridine or uridine derivatives, can be turned into a wound dressing together with uridine or uridine derivatives. Uridine or uridine derivatives stick onto the nanofiber structure, the adhered uridine molecules are released in a controlled manner, and after bringing into wound dressing and sterilizing, controlled uridine release continue. It is evidenced that after sterilization it provides faster healing in experimental animals starting from the first day, when compared to commercial product and nanofiber wound dressing not containing uridine. Therefore, in the light of the present knowledge in the related art, this is an unusual development with respect to production, characterization and effectiveness of the product. The reason for adding uridine or uridine derivatives in PCL polymer is that uridine or uridine derivatives activate anti-oxidant systems, exhibit anti- apoptotic properties, increase regeneration in cells and tissues, and accelerate many steps of wound healing due to its anti-inflammatory properties. Due to these properties adding uridine or uridine derivatives to the wound dressing is useful in the treatment of all kinds of wounds and in accelerating the healing processes thanks to its controlled and stable release within a long period of time. The increase in wound closure rates is because of the above mentioned physiological and pharmacological effectiveness of uridine or uridine derivatives. The effects are described below and the reason for delayed wound healing under conditions where uridine is not added is emphasized.

The haemostasis phase begins to ensure coagulation following epithelial cell injury. Platelet aggregation occurs at the wound site. As this aggregation progresses, a fibrin clot forms, and coagulation factors are released in order to prepare ground for the next wound healing stages. An (2019) studied the effects of uridine and its phosphate nucleotides on haemostasis parameters, and how uridine, UMP, UDP and UTP nucleotides affect platelet aggregation with an optical aggregometer. As a result of the study, it was determined that uridine supports collagen-induced aggregation, and that UMP does not have any function. It has been shown that UDP and UTP activate aggregation at low concentrations, and inhibit platelet aggregation at high concentrations (An, 2019). Based on this study; it is believed that the effect of uridine on platelet aggregation and haemostasis phase is the cause of significant wound healing on uridine-containing surfaces compared to commercial and pure PCL dressings. To show this, in vivo experiments were carried out by proceeding into the activity step of the study.

Creation of wound model and dressing application

For a full-thickness skin defect to be generated in rats, a 1 cm x 1 cm skin layer was removed with the help of a scalpel. With this method, a total of 4 wound models were created on the back of the rats. The wounds on the upper left were covered with Tegaderm commercial dressing, those on the upper right with pure PCL nanofiber surface, those on the lower left with PCL nanofiber surface containing 0.5% uridine, and those on the lower right with PCL nanofiber surface containing 1% uridine. In the last stage of the operation, the surgical area was covered with a protective cover and sterile sponge to protect the wound area. The rats, whose wound areas were closed, were labelled on their tails, and placed in their cages, and were given free access to food and water starting from the 4th post-operative hour. The studies were repeated on 8 rats, and the body weights of the rats were measured during the wound follow-up process.

Assessment of wound healing

The rate of wound area reduction was measured on days 0, 1 , 3, 5, 7, 9, 16, and 21 using the planimetric method. Transparent acetate film was placed on the wound and the borders of the wound area with the intact tissue were determined with an acetate pen. Wound images on acetate paper were scanned and transferred to the computer, and wound areas were determined in cm ² using Imaged software. Wound reduction rates were calculated using the formula given below.

Wound reduction (%) = 100-[ ( A _WO und(n) / A _o )* 100 ] Awound(n) = n. Wound area on measurement day Ao = Original wound area (0. day)

Interpretation of in vivo results

Upon comparing the first day results, the absence of a significant difference in terms of wound reduction with the commercial product and the PCL dressing compared to uridine-containing PCL supports that uridine has a positive effect on wound healing. On the third day, 22.9% and 26.2% wound reduction occurred in the commercial product and uridine-free PCL dressing groups, respectively. The observed 50.7% wound reduction rate in the 0.5% uridine dressing group suggested that half of the wound area gets closed in 3 days by adding 0.5% uridine to the dressing. This rate was 42.9% in the dressing group containing 1% uridine. On the 3rd day, the change in the wound areas where uridine-containing surfaces were used remained statistically significant.

Figure 1 shows the values average closure rate of wounds formed on the 0 ^th day in percent (%) as mean ± standard error of means (n=8) on a daily basis in the full-layer in vivo wound model.

As seen in figure, wound healing in the groups using uridine-containing nanofiber dressings was faster and the wound closure rates were significantly higher than in the groups using commercial product and uridine-free PCL nanofiber surface. It is observed that the wound healing process continues until the 5 ^th day. When the 7th day is examined, it is seen that although the significance between the commercial product and the uridine-containing nanofibrous surfaces in terms of wound closure disappears in the groups, the significance between the uridine-containing nanofibrous surfaces and the uridine-free PCL nanofibrous surface continues until the 9 ^th day. This observed result suggests that the rapid release of uridine on the first day has a significant effect on wound healing. When the results are compared to the drug release data obtained from in vitro experiments, it is believed that the release of uridine from the surfaces for 5 days is also the reason for the significant wound closure observed up to the 5 ^th day of application of uridine-containing surfaces on the wound in comparison to other surfaces in in vivo experiments.

The wound healing process is regulated by a wide variety of growth factors, cytokines, and hormones (Werner and Grose, 2003). In recent studies, it has been revealed that nitric oxide (NO) and reactive oxygen derivatives are also important regulators in the wound healing process. Low reactive oxygen derivatives levels are also key mediators of intracellular signalling. It is essential for effective defence against pathogens. A study (Roy et aL, 2006) revealed that optimum hydrogen peroxide (H2O2) levels are significant for wound angiogenesis. However, due to high reactive values, having high reactive oxygen derivatives levels cause oxidative stress and negatively impact wound healing. Reactive oxygen derivatives can cause sustained secretion of proinflammatory cytokines, induction of matrix metalloproteases, oxidative changes in proteins, lipids, and nucleic acids; may alter ECM proteins and cause impaired fibroblast and keratinocyte function. Therefore, strict regulation of reactive oxygen derivatives production and detoxification is crucial for the normal healing process (Dunnill et aL, 2017; Schafer and Werner, 2008)

Al et al. (2020) investigated the effects of uridine treatment on reactive oxygen types in a neonatal hyperoxic brain injury model. They studied changes in antioxidant enzymes such as glutathione peroxidase (GSH-Px), catalase (CAT) and superoxide dismutase (SOD) that protect cells from exposure to oxidative stress, as well as malondialdehyde (MDA), a marker of oxidative stress, with exogenous uridine treatment. They showed that uridine increased levels of SOD and GSH-Px that were reduced due to hyperoxia, prevented the increases in MDA levels, and exhibited anti oxidative properties by increasing levels of the oxidative stress-sensitive DJ-1 protein (Al et aL, 2020). Antioxidant substances that modulate levels of reactive oxygen species in wound tissues positively affect wound healing. The antioxidant property of uridine may be considered as the reason why uridine-containing wound dressings perform better in wound healing than those that do not contain uridine.

Oxidative stress is also closely associated with cell aging. A study investigated antiaging effect of uridine in an in vitro and in vivo intestinal cell senescence model. It has been indicated that with uridine supplementation, markers of aging were significantly reduced, and the proliferation ability of cells in the uridine-treated group increased significantly when compared to the control group (Jiang & Zhao, 2022).

The effect of Uridine on human corneal epithelial cells and keratocytes in vitro and the ocular surface improvement of topical application of uridine-containing eye drops in a dry eye model in vivo were studied. The studies showed that uridine did not cause any cytotoxicity and provided cell proliferation. It significantly increased hyaluronic acid (HA) biosynthesis and glycosaminoglycan (GAG) concentration in corneal epithelial cells and keratocytes (Oh et aL, 2007). Uridine is converted to UTP by uridine kinase and subsequently synthesized UDP-Glucose is used in the in vivo synthesis of HA (Magee et aL, 2001). It has been shown in many studies that hyaluronic acid accelerates wound healing in the skin (Abatangelo et aL, 1983; Frenkel, 2014; Neuman et aL, 2015). Since hyaluronic acid has a short half-life in keratinocyte cells in the epidermis, its in vivo use in wound healing may be limited when administered exogenously. In our study, one of the factors that uridine accelerates wound healing may be that exogenous uridine increases the endogenous biosynthesis of HA. Matrix metalloproteinases (MMPs) are involved in all phases of normal wound healing. They provide correct alignment of collagen fibers for the migration of fibroblasts. MMPs, which are necessary for wound contraction, also have an important role in angiogenesis (Kordestani, 2019). MMP-9 is type IV collagenase that is optimally synthesized during normal wound healing. It supports re-epithelialization by breaking down the basement membrane and provides an environment for the migration of keratinocytes to the wound and stimulates wound closure. In the inflammatory state of the wound, MMP-9 synthesis and activation reaches a high level. This prevents the formation of new basement membrane and delays wound healing (Nguyen et al., 2016; Reiss et aL, 2010; Sabino and auf dem Keller, 2015). In a study the effects of uridine administration on hippocampal MMP-9 levels in rats with REM sleep deprivation were investigated, and it was concluded that uridine treatment reversed the decrease in MMP-9 activity (Cakir et aL, 2022). Another study showed that uridine supplementation in corneal epithelial cell culture reduces MMP-9 levels (Oh et aL, 2007). As these studies in the literature show, it is not fully understood how uridine affects MMP-9 levels. Within the studies of the invention, no analysis has been conducted on MMP-9 activity in epithelial cells. It is known that MMP-9 synthesis increases in case of increased inflammation in the wound. Due to the anti-inflammatory properties of uridine, delayed wound healing in wound dressings with high uridine concentration may be because of the inability of suppressed inflammatory cytokines to adequately activate MMP-9.

Although the roles of the uridine nucleotide receptors in the skin have not been discovered yet, it has been shown in a study by Burrel et aL (2003) that P2Y2 and P2Y4 receptors play an active role in the keratinocyte cell proliferation response. It is believed that nucleotides acting on P2Y receptors affect keratinocyte growth and may be a mechanism that plays a role in the physiological regulation of healing, especially after epidermis damage (Burrell et aL, 2003). No specific receptor for uridine has yet been identified. Therefore, it can be assumed that uridine may show its effects indirectly through the binding of UDP and UTP to P2Y2, P2Y4 and P2Y6 purinergic receptors (Cansev, 2007; Cicko et aL, 2015)

Regeneration can be briefly defined as the regeneration or replacement of damaged or diseased tissues (Jopling et aL, 2011). A study by Liu et aL (2022) studied how regenerative capacity is supported by metabolic mechanisms, and it has been shown that uridine treatment increases regeneration and repair in various tissue types. Uridine treatment has been shown to regulate proinflammatory cytokine levels, promote tissue repair, provide higher grip strength and longer running distance in a muscle wound model in rats. Additionally, uridine supplementation regulated pyrimidine nucleotide biosynthesis in muscle fibers and expression of genes associated with muscle structure development. The functioning of the heart undergoing myocardial infarction is improved by uridine treatment. In addition to muscle and cardiac injury patterns, uridine treatment also facilitated liver and cartilage tissue regeneration. When the effect on hair follicles is examined, it is shown that new hair follicles are formed with high proliferation following uridine supplementation. The facts that uridine is more abundant in cells and tissues with high regenerative potential indicate that it is a powerful factor promoting regeneration (Liu et al., 2022). Considering the beneficial roles of uridine in promoting tissue repair and improving physiological functions, the fact that uridine-containing nanofiber dressings support wound healing and tissue repair is in line with these findings. It can be considered that uridine supplementation promotes regeneration and repair by reshaping metabolic adaptation.

REFERENCES

An, M. (2019). Uridin ve Nukleotidlerinin Hemostaz Parametreleri Uzerine Etkileri. Bursa Uludag llniversitesi.

Eming, S. A., Martin, P., & Tomic-Canic, M. (2014). Wound repair and regeneration: Mechanisms, signaling, and translation. In Science Translational Medicine (Vol. 6, Issue 265). https://doi.org/10-1126/scitranslmed.3009337

Cicko, S., Grimm, M., Ayata, K., Beckert, J., Meyer, A., Hossfeld, M., Zissel, G., Idzko, M., & Muller, T. (2015). Uridine supplementation exerts anti-inflammatory and anti- fibrotic effects in an animal model of pulmonary fibrosis. Respiratory Research, 16(1), 1-10. https://doi.org/10.1186/s12931-015-0264-9

Jiang, W. G., Sanders, A. J., Ruge, F., & Harding, K. G. (2012). Influence of interleukin- 8 (IL-8) and IL-8 receptors on the migration of human keratinocytes, the role of PLC-y and potential clinical implications. Experimental and Therapeutic Medicine, 3(2), 231-236. https://doi.org/10.3892/etm.2011.402

Johnson, B. Z., Stevenson, A. W., Prele, C. M., Fear, M. W., & Wood, F. M. (2020). The Role of IL-6 in Skin Fibrosis and Cutaneous Wound Healing. Biomedicines, 3(5), 101. https://doi.org/10.3390/biomedicines8050101

Werner, S., & Grose, R. (2003). Regulation of wound healing by growth factors and cytokines. In Physiological Reviews (Vol. 83, Issue 3). https://doi.Org/10.1152/physrev.2003.83.3.835

Roy, S., Khanna, S., Nallu, K., Hunt, T. K., & Sen, C. K. (2006). Dermal wound healing is subject to redox control. Molecular Therapy, 13(1). https://doi.Org/10.1016/j.ymthe.2005.07.684

Dunnill, C., Patton, T., Brennan, J., Barrett, J., Dryden, M., Cooke, J., Leaper, D., & Georgopoulos, N. T. (2017). Reactive oxygen species (ROS) and wound healing: the functional role of ROS and emerging ROS-modulating technologies for augmentation of the healing process. International Wound Journal, 14(1). https://doi.org/10-1111/iwj.12557

Schafer, M., & Werner, S. (2008). Oxidative stress in normal and impaired wound repair. In Pharmacological Research (Vol. 58, Issue 2). https://doi.Org/10.1016/i.Dhrs.2008.06.004

Al, N., Qakir, A., KOQ, C., Cansev, M., & Alkan, T. (2020). Antioxidative effects of uridine in a neonatal rat model of hyperoxic brain injury. Turkish Journal of Medical Sciences, 50(8). https://doi.org/10.3906/sag-2002-14 Jiang, N., & Zhao, Z. (2022). Intestinal aging is alleviated by uridine via regulating inflammation and oxidative stress in vivo and in vitro. Cell Cycle, 27(14), 1519- 1531. https://doi.orq/10.1080/15384101 .2022.2055252

Oh, J. Y., In, Y. S., Kim, M. K., Ko, J. H., Lee, H. J., Shin, K. C., Lee, S. M., Wee, W. R., Lee, J. H., & Park, M. (2007). Protective effect of uridine on cornea in a rabbit dry eye model. Investigative Ophthalmology and Visual Science, 48(3). https://doi.Org/10.1167/iovs.06-0809

Magee, C., Nurminskaya, M., & Linsenmayer, T. F. (2001). UDP-glucose pyrophosphorylase: Up-regulation in hypertrophic cartilage and role in hyaluronan synthesis. Biochemical Journal, 360(3). https://doi.org/10.1042/0264-

6021 :3600667

Abatangelo, G., Martelli, M., & Vecchia, P. (1983). Healing of hyaluronic acid-enriched wounds: Histological observations. Journal of Surgical Research, 35(5), 410-416. https://doi.Org/10.1016/0022-4804(83)90030-6

Frenkel, J. S. (2014). The role of hyaluronan in wound healing. International Wound Journal, 11(2), 159-163. https://doi.Org/10.1111/j.1742-481X.2012.01057.x

Neuman, M. G., Nanau, R. M., Oruna-Sanchez, L., & Coto, G. (2015). Hyaluronic Acid and Wound Healing. Journal of Pharmacy & Pharmaceutical Sciences, 18(1 ), 53. https://doi.org/10.18433/J3K89D

Kordestani, S. S. (2019). Wound Healing Process. In Atlas of Wound Healing A Tissue Regeneration Approach.

Nguyen, T. T., Mobashery, S., & Chang, M. (2016). Roles of Matrix Metalloproteinases in Cutaneous Wound Healing. In Wound Healing - New insights into Ancient Challenges, https://doi.org/10.5772/64611

Reiss, M. J., Han, Y. P., Garcia, E., Goldberg, M., Yu, H., & Garner, W. L. (2010). Matrix metalloproteinase-9 delays wound healing in a murine wound model. Surgery, 147(2). https://doi.Org/10.1016/j.surg.2009.10.016

Sabino, F., & auf dem Keller, U. (2015). Matrix metalloproteinases in impaired wound healing. Metalloproteinases In Medicine, 2, 1-8. https://doi.Org/10.2147/MNM.S68420

Cakir, A., Ocalan Esmerce, B., Aydin, B., Koc, C., Cansev, M., Gulec Suyen, G., & Kahveci, N. (2022). Effects of uridine administration on hippocampal matrix metalloproteinases and their endogenous inhibitors in REM sleep-deprived rats. Brain Research, 1793, 148039. https://doi.org/10.1016/j-brainres.2022.148039

Burrell, H. E., Bowler, W. B., Gallagher, J. A., & Sharpe, G. R. (2003). Human keratinocytes express multiple P2Y-receptors: Evidence for functional P2Y1 , P2Y2, and P2Y4 receptors. Journal of Investigative Dermatology, 120(3). https://doi.Org/10.1046/J.1523-1747.2003.12050.x

Cansev, M. (2007). Involvement of Uridine-Nucleotide-Stimulated P2Y Receptors in Neuronal Growth and Function. Central Nervous System Agents in Medicinal Chemistry, 7(4), 223-229. https://doi.org/10.2174/187152407783220814

Jopling, C., Boue, S., & Belmonte, J. C. I. (2011). Dedifferentiation, transdifferentiation and reprogramming: Three routes to regeneration. In Nature Reviews Molecular Cell Biology (Vol. 12, Issue 2). https://doi.org/10.1038/nrm3043 Liu, Z., Li, W., Geng, L., Sun, L., Wang, Q., Yu, Y., Yan, P., Liang, C., Ren, J., Song, M., Zhao, Q., Lei, J., Cai, Y., Li, J., Yan, K., Wu, Z., Chu, Q., Li, J., Wang, S., ... Liu, G.-H. (2022). Cross-species metabolomic analysis identifies uridine as a potent regeneration promoting factor. Cell Discovery, 8(1), 6. https://doi.Org/10.1038/S41421 -021 -00361 -3