FIELD OF THE INVENTION The invention relates to chemically modified hyaluronic acid/nucleic acid films and matrices for use in gene therapy.

BACKGROUND OF THE INVENTION Gene therapy provides the intracellular introduction and expression of therapeutic genes in human somatic cells to achieve a therapeutic effect for both inherited and acquired disease. (Eming et a/., British Journal of Plastic Surgery, Vol. 50, p. 491-500) Current issues associated with disease therapy using recombinant proteins, such as frequent administration and formulation obstacles concerning protein denaturation, are circumvented using gene therapy. Presently, the greatest issue associated with gene therapy is the development of an effective delivery vehicle. Experimental gene delivery vehicles such as adenoviral and retroviral vectors have proven to be highly effective for gene transfer. Problems associated with these vectors include immunogenicity, transient expression and mutagenicity. Philip et a/. (#5,861,314) describes Adeno-associate viral (AAV) liposomes and methods related to the delivery of genes for therapy in certain cell lines. Cationic liposomes have been unsuccessful as gene therapy vehicles in clinical use due to transient expression. In contrast, the present invention allows sustained delivery.

Recent developments in using the biodegradable synthetic polymer poly-lactide-co- glycolide microspheres and nanospheres as experimental gene delivery vehicles have partially addressed the potential problems associated with using viral vectors in gene therapy. Induction of inflammatory response has been seen with this polymer (van der

Giessen, et al., Circulation 94: 1690-1697,1996). The induction of inflammatory responses when viral vectors are used in vivo has thus not been adequately resolved.

Tissue repair is one area that lends itself well to the methods of gene therapy. Many growth factors are involved in the tissue events such as cell migration, cell proliferation and the formation of the extracelluar matrix that result in healing. Epidermal delivery of DNA encoding wound healing growth factors such as platelet derived growth factor or fibroblast growth factor is a useful strategy in wound care management and especially in the treatment of chronic wounds. The incidence and prevalence of chronic wounds are especially high in the elderly inpatient and nursing-home population. Because these wounds cause a major disability and are characterized by chronically and frequent relapse, they have a significant impact on the socioeconomic well being of the population and attract enormous health care expenditures that exceeds billions of dollars a year in the U. S. in 1999.

Diabetic ulcer, pressure ulcer and venous ulcer constitute three of the largest groups of chronic wounds. These chronic wounds do not follow the expected path of healing even when adequate and appropriate care is provided. Current wound management generally involves treating infection, cleansing the wound, and debriding the wound site to prevent complications as well as relieving pain and discomfort. Research on wound healing has demonstrated that some traditionally used wound care products do little to enhance healing and can actually delay healing. The delay is caused by dehydration of the wound, scab formation, concentration-dependent toxicity or an actual adverse pharmacologic effect on the healing process. These agents include topical corticosteroids, liquid detergent, providone-iodine, hydrogen peroxide and hypochlorite solutions. (Findlay, D., Am. Family Physician, 54: 1519-28,1996) Surgery followed by skin graft is the only therapeutic option when ulcers are large and non-healing.

No chronic wound healing therapeutic entity based solely on gene therapy exists in the current market.

Many wound healing therapies involve the use of film and or matrices composed of collagen and other natural or synthetic polymers. Silver et al. in U. S. patents 4,970,298 and 4,703,108 describe a biodegradable matrix made from collagen with or without hyaluronic acid and fibronectin for the enhancement of wound healing.

Hyaluronic acid is a major component of the extra-cellular matrix synthesized in the plasma membrane of fibroblasts and other cells. Another name for hyaluronic acid using standard polysaccharide nomenclature is hyaluronan. The sodium salt of hyaluronic acid is called hyaluronate which is the predominant form at physiological pH. All these forms will hereafter be collectively called HA. (The Chemistry, Biology and Medical Applications of Hyaluronan and its Derivatives, ed. T. C.

Laurent, London, 1998). The structure consists of a 200 to 10,000 linear polyanionic polymer of repeating disaccharide units [D-glucuronic acid (l-G-3) N-acetyl-D- glucosamine] n. HA is one of several glycosaminoglycans that are widely distributed throughout the body predominantly in the extracellular matrix of connective tissue.

Viscoelasticity (a property combining the elastic behavior of a gel and the viscous behavior of a solution) and non-immunogenicity make derivatives of HA ideal for uses in biomaterials and drug delivery systems. Hamilton et al. in U. S. patent 4,937,270 describes the method of making a water insoluble biocompatible gel using hyaluronic acid.

Pouyani et al., (U. S. patent5,874,417) describes the hydrazide linkage chemistry utilized in the crosslinking of HA to another component or components. This chemistry differs from prior art methods of derivatizing HA in two ways. First, there is little change to the HA molecules, especially the molecular weight, and second, the chemistry is preformed under relatively mild and selective conditions. U. S. patents; 5,652,347 and 5,616,568 further describe the methods of functionalizing a HA backbone by covalent attachment of pendent hydrazido groups. These patents and all patents cited herein are incorporated in their entirety by reference.

Hyaluronic acid derivative and compositions have been prepared as biomedical devices for use in a variety of medical applications. Genzyme, Inc. developed a bioabsorbable film (SepraFilmO) for prevention of post-surgical adhesions (Vercruysse et al., Critical Reviews in Therapeutic Drug Carrier Systems, 15 (5): 513-555 (1998)).

Recombinant human growth factors have emerged as potential wound healing agents. Platelet derived growth factor (PDGF) plays a crucial role in wound healing (Pierce et al., J Cell Biochem. 45: 319-326,1991). PDGF is one of the first growth factors to be released at the site of injury and participates in regulating all phases of the wound healing response. The recent introduction in the US of the first recombinant growth factor-Regranext (becaplermin, platelet derived growth factor, rPDGF-ß) gel has

somewhat altered the outlook on chronic topical wound healing. However, the gel must be repeatedly applied in a protracted manner during the course of treatment, that may last up to 11 weeks, in order to achieve a desirable therapeutic effect. Due to the mode of application, the levels of PDGF-are expected to fluctuate considerably with each application. Moreover, the stability of the product, especially the three-dimensional conformations of the recombinant protein, may be easily disrupted by the fluctuation in environmental factors, including pH, temperature, ionic compositions. A slight change in the conformation may render the recombinant proteins ineffective.

SUMMARY OF THE INVENTION The present invention includes a HA-matrix system comprising a dihydrazide derivatized hyaluronic acid crosslinked to a nucleic acid. The dihydrazide may be adipic dihydrazide. The nucleic acid may include a nucleotide sequence which is at least 70% identical to the nucleotide sequence set forth in SEQ ID NO. 1 or it may encode a protein which includes an amino acid sequence which is at least 70% identical to the amino acid sequence set forth in SEQ ID NO. 2. The nucleic acid of the HA-matrix system may be plasmid DNA, linear, single or double stranded DNA or RNA. The nucleic acids of the HA-matrix system may also encode PDGF/3 or other genes whose expression leads to the enhancement of the wound healing process.

In preferred embodiments, the invention includes an HA-matrix system comprising hyaluronic acid crosslinked with adipic dihydrazide wherein the adipic dihydrazide is further crosslinked to a nucleic acid wherein said nucleic acid has a nucleotide sequence which encodes a protein of at least 70% identity to the reference amino acid sequence set forth in SEQ ID NO. 2, wherein identity is determined using the BLASTP algorithm, where the parameters are selected to give the largest match between the sequences tested, over the entire length of the reference sequence.

Furthermore, the invention includes methods of transfecting cells comprising including the cells with the HA-matrix system of the invention; the cells transfected by these methods are also a part of the invention. Other methods of the invention include treating subjects, who may have a skin injury, who are in need of

enhanced wound healing, including contacting the body of the subject with the HA-matrix system.

In preferred embodiments, the invention includes a method of treating a skin injury in a subject comprising contacting the skin of the subject with a HA-matrix system comprising hyaluronic acid crosslinked with adipic dihydrazide wherein the adipic dihydrazide is further crosslinked to a plasmid whose nucleotide sequence comprises that set forth in SEQ ID NO. 1.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1: Scanning electron micrograph of a typical HA film comprising DNA.

FIGURE 2: Scanning electron micrograph of a typical HA-matrix.

FIGURE 3: HA-films in ethidium bromide under UV light.

FIGURE 4: HA-films in ethidium bromide under UV light.

FIGURE 5: Electrophoretic mobility analysis of DNA eluted from an HA- matrix.

FIGURE 6: Electrophoretic mobility analysis of DNA eluted from an HA- film.

FIGURE 7: CHO cells transfected with HA-matrix and HA-film comprising pCMVß vector p-galactosidase reporter gene construct.

FIGURE 8: Schematic flow diagram for preparing the HA-film or HA-matrix with conjugated DNA.

FIGURE 9: Controlled release of DNA from HA-films and HA-matrices in phosphate buffer containing hyaluronidase.

FIGURE 10: In vivo gene transfer by HA-matrix.

FIGURE 11: Map of plasmid pFLAG-CMV5 DETAILED DESCRIPTION This invention relates to methods and compositions for enhancing tissue repair involving a noninflammatory biodegradable and biocompatible hyaluronic acid (crosslinked with adipic dihydrazide) derived film and matrix system for sustained transfer of nucleic acid from the film or matrix to the cell. Without being bound to a single theory, the hyaluronic acid of the HA-matrix system of the present invention may be crosslinked to the dihydrazide wherein the dihydrazide is further crosslinked to a nucleic acid.

Applicants have developed a noninflammatory biodegradable and biocompatible hyaluronic acid (crosslinked with adipic dihydrazide) derived HA-matrix system for sustained transfer of nucleic acids which may encode a gene such as the growth factor, PDGF-P. The HA-matrix system of the invention may be used in gene therapy applications to treat medical conditions. For example, the HA-matrix system may be used to achieve the goal of accelerating wound healing. In contrast to other nonviral experimental gene delivery vehicles, which seek to physically disperse nucleic acids (with or without the aid of a nucleic acids condensing agent) into the nucleic acids delivery vehicles, and thereby control the nucleic acids release by limiting its solubility or by the formation of physical diffusion barriers (the vehicle), this invention covalently conjugates the nucleic acids to the hyaluronic acid via a covalent linkage using, for example dihydrazide chemistry disclosed in U. S. patents 5,874,417; 5,652,347 and 5,616,568. The release of nucleic acids is mediated by a slow degradation of the hyaluronic acid delivery vehicle; on this basis it is believed, without being bound by theory, that the HA-matrix system of the invention attains a sustained transfer of nucleic acids to host cells. The slow degradation of the hyaluronic acid may occur by the action of hyaluronic acid degrading

enzymes (hyaluronidases) or by hydrolysis. The sustained transfer of the nucleic acids from the HA-matrix system of the invention to a host cell is in contrast to other gene transfer mechanisms, such as viruses, which transfer nucleic acids to their host cells immediately. After a single application of the HA-matrix system of the invention, the nucleic acids may be transferred to host cells for several days as the hyaluronic acid degrades and liberates nucleic acid molecules. For example, over the course of 12 days, approximately 10% of the nucleic acids of a single application may be released from the HA-matrix system of the invention. Any rate of nucleic acid-host cell transfer associated with the HA-matrix system of the invention which is adequate to cause a desired therapeutic effect is within the scope of the invention. The rate of release of nucleic acids from the HA-matrix system of the invention may be decreased by increasing the level of crosslinking between the dihydrazide derivatized hyaluronic acid and the nucleic acid and increased by decreasing the level of crosslinking between the dihydrazide derivatized hyaluronic acid and the nucleic acid. Furthermore, so as to aid the sustained transfer of nucleic acids, the compositions of the HA-matrix system may be applied to a wound and covered with an occlusive dressing so as to decrease evaporation and to inhibit sloughing of the HA-matrix system from the wound site due to sweat or friction with clothing.

Other drugs and genes may also be covalently attached to the derivatized HA for sustained transfer and consequent enhancement of a therapeutic effect. This HA- matrix sustained delivery system will provide substantially improved prospects for accelerating chronic wound healing through a single application, which overcomes the disadvantages associated with the currently available topical treatments for chronic wounds. While not necessary, multiple applications may also lead to an improved therapeutic result. Problems associated with targeting of nucleic acids to host cells are avoided by topical administration of the HA-matrix system to the wound site. HA, itself, is also known to aid in tissue repair and is more bioavailable than other delivery vehicles.

HA plays an active role in tissue repair by promoting angiogenesis and cell recruitment.

The HA-matrix system of the invention may include any nucleic acids which, when expressed in a host cell of a subject, yield a desired therapeutic effect. In preferred embodiments, the nucleic acids of the HA-matrix system encode proteins which accelerate the process of wound healing when produced by a host cell. However, any gene therapy indication wherein a sustained transfer of nucleic acids would be beneficial are

within the scope of the invention. For example, a sustained transfer of genes, to skin cells, which express a protein which is inhibitory to herpes virus (HSV) replication would be a suitable embodiment of this invention. A similar use in the inhibition of the human papilloma virus (HPV) would also be a suitable embodiment of this invention. A further specific embodiment of the invention may include the treatment of skin cancers; genes which inhibit skin cell replication or replace the function of mutated genes which led to the development of the skin malignancy may be transferred to host malignant skin cells.

The preferred gene for the transfer to skin cells in wound healing applications is PDGF-ß.

Preferably, plasmid DNA is transferred to host cells in the practice of this invention, however, the transfer of linear DNA, single or double stranded DNA or RNA is within the scope of this invention.

The transfer of nucleic acids which, when present in a host cell, cause the expression of a protein is a preferred embodiment of the invention. However, embodiments wherein nucleic acids designed such that, when present in a host cell, they integrate into a host cell chromosome for the purpose of mutating a gene at the integration locus are within the scope of the invention.

The compositions of the invention form biocompatible gels or hydrogels which may be topically applied for sustained gene transfer. The term"gel"is intended to mean viscous or semi-solid and jelly-like. A gel comprising dihydrazide derivatized hyaluronic acid which is crosslinked to a nucleic acid is referred to as a HA- gel. The term"hydrogel"is intended to mean macromolecular networks, which swell in water. A hydrogel comprising dihydrazide derivatized hyaluronic acid which is crosslinked to a nucleic acid is referred to as a HA-hydrogel. The term"film"is intended to mean a substance formed by compressing a gel or by allowing or causing a gel to dehydrate. A film comprising dihydrazide derivatized hyaluronic acid which is crosslinked to a nucleic acid is referred to as a HA-film. The term"matrix"is intended to mean a substance formed by lyophilizing a gel. A matrix comprising dihydrazide derivatized hyaluronic acid which is crosslinked to a nucleic acid is referred to as a HA- matrix. The term"HA-matrix system"refers to HA-matrices, HA-films, HA-gels and HA- hydrogels. The covalently crosslinked derivatives of hyaluronate yield hydrogels with enhanced rheological and mechanical properties with differences in hyaluronidase degradation and thus differences in the kinetics of DNA release.

The term"therapeutic agent"refers to a substance, which, when delivered to a subject, causes a physiological effect in the subject.

The term"protein"refers to any peptide or polypeptide containing two or more amino acids, modified amino acids, or amino acid derivatives."Protein", by way of example, and without excluding other types of proteins, includes enzymes and structural proteins.

A"DNA molecule","nucleic acid molecule"or"nucleic acid" refers to the phosphodiester polymeric form of ribonucleosides (adenosine, guanosine, uridine or cytidine;"RNA molecules") or deoxyribonucleosides (deoxyadenosine, deoxyguanosine, deoxythymidine, or deoxycytidine;"DNA molecules"), or any phosphoester analogs thereof, such as phosphorothioates and thioesters, in either single stranded form, or a double-stranded helix. Double stranded DNA-DNA, DNA-RNA and RNA-RNA helices are possible. A more specific term,"oligonucleotide", refers to a nucleic acid of 20 bases in length, or less. Thus, these terms include double-stranded DNA found, inter alia, in linear (e. g., restriction fragments) or circular DNA molecules, plasmids, and chromosomes. In discussing the structure of particular double-stranded DNA molecules, sequences may be described herein according to the normal convention of giving only the sequence in the 5'to 3'direction along the nontranscribed strand of DNA (i. e., the strand having a sequence homologous to the mRNA). A"recombinant DNA molecule"is a DNA molecule that has undergone a molecular biological manipulation.

A"DNA sequence"or"nucleotide sequence"is a series of nucleotide bases (also called"nucleotides") in DNA and RNA, and means any chain of two or more nucleotides. A nucleotide sequence typically carries genetic information, including the information used by cellular machinery to make proteins. These terms include double or single stranded genomic DNA or cDNA, RNA, any synthetic and genetically manipulated nucleic acid, and both sense and anti-sense nucleic acids. This includes single-and double-stranded molecules, i. e., DNA-DNA, DNA-RNA and RNA- RNA hybrids, as well as"protein nucleic acids" (PNA) formed by conjugating bases to an amino acid backbone. This also includes nucleic acids containing modified bases, for example thio-uracil, thio-guanine and fluoro-uracil.

The term"heterologous"refers to a combination of elements not naturally occurring. For example, heterologous DNA refers to DNA not naturally located in the cell, or in a chromosomal site of the cell. Heterologous nucleic acids in a cell may include nucleic acids which include nucleotide sequences which naturally occur in the cell as well as nucleic acids which include nucleotide sequences which do not naturally occur in the cell. A heterologous expression regulatory element is such an element operatively associated with a different gene than the one with which it is operatively associated in nature.

The"nucleic acids"and"nucleic acid molecules"herein may be flanked by natural regulatory (expression control) sequences, or may be associated with heterologous sequences, including promoters, internal ribosome entry sites (IRES) and other ribosome binding site sequences, enhancers, response elements, suppressors, signal sequences, polyadenylation sequences, introns, 5'-and 3'-non-coding regions, and the like.

The nucleic acids may also be modified by many means known in the art. Non-limiting examples of such modifications include methylation,"caps", substitution of one or more of the naturally occurring nucleotides with an analog, and internucleotide modifications such as, for example, those with uncharged linkages (e. g., methyl phosphonates, phosphotriesters, phosphoroamidates, carbamates, etc.) and with charged linkages (e. g., phosphorothioates, phosphorodithioates, etc.). Nucleic acids may contain one or more additional covalently linked moieties, such as, for example, proteins (e. g., nucleases, toxins, antibodies, signal peptides, poly-L-lysine, etc.), intercalators (e. g., acridine, psoralen, etc.), chelators (e. g., metals, radioactive metals, iron, oxidative metals, etc.), and alkylators. The nucleic acids may be derivatized by formation of a methyl or ethyl phosphotriester or an alkyl phosphoramidate linkage. Furthermore, the nucleic acids herein may also be modified with a label capable of providing a detectable signal, either directly or indirectly. Exemplary labels include radioisotopes, fluorescent molecules, biotin, and the like.

The term"host cell"means any cell of any organism that is selected, modified, transformed, grown, or used or manipulated in any way, for the production of a substance by the cell, for example the expression by the cell of a gene or DNA sequence.

Proteins are made in the host cell using instructions in DNA and RNA, according to the genetic code. Generally, a DNA sequence having instructions for a

particular protein or enzyme is"transcribed"into a corresponding sequence of RNA. The RNA sequence in turn is"translated"into the sequence of amino acids which form the protein. Each amino acid is represented in DNA or RNA by one or more triplets of nucleotides, called a codon. The genetic code has some redundancy, also called degeneracy, meaning that most amino acids have more than one corresponding codon corresponding to an amino acid. The amino acid lysine (Lys), for example, can be coded by the nucleotide triplet or codon AAA or by the codon AAG. Codons may also form translation stop signals, of which there are three. Because the nucleotides in DNA and RNA sequences are read in groups of three for protein production, it is important to begin reading the sequence at the correct nucleotide, so that the correct triplets are read. The way that a nucleotide sequence is grouped into codons is called the"reading frame." The term"gene"refers to a DNA sequence that encodes or corresponds to a particular sequence of amino acids that comprise all or part of one or more proteins, and may or may not include regulatory DNA sequences, such as, for example, promoter sequences, which determine, for example, the conditions under which the gene is expressed. The term"gene"also includes DNA sequences which are transcribed from DNA to RNA, but are not translated into an amino acid sequence.

A"coding sequence"or a sequence"encoding"an expression product, such as a RNA, polypeptide, or protein, is a nucleotide sequence that, when expressed, results in the production of that RNA, polypeptide, or protein, i. e., the nucleotide sequence encodes an amino acid sequence for that polypeptide or protein. A coding sequence for a protein may include a start codon (usually ATG) and a stop codon.

A nucleic acid may also"encode"a gene or DNA sequence in that the nucleotide sequence of the gene or DNA sequence is contained within the nucleic acid.

A"promoter sequence"is a DNA regulatory region capable of binding RNA polymerase in a cell and initiating transcription of a downstream (3' direction) coding sequence. A promoter sequence is bounded typically at its 3'terminus by the transcription initiation site and extends upstream (5'direction) to include bases or elements necessary to initiate transcription at higher or lower levels than that of a promoter without said bases or elements. Within the promoter sequence will be found a transcription initiation site (conveniently defined, for example, by mapping with nuclease S1), as well

as protein binding domains (consensus sequences) responsible for the binding of RNA polymerase.

A coding sequence is"under the control of'or"operatively associated with"transcriptional and translational control sequences in a cell when RNA polymerase transcribes the coding sequence into mRNA, which may then be spliced (if it contains introns) and may also be translated into the protein encoded by the coding sequence.

The terms"express"and"expression"mean allowing or causing the information in a gene or DNA sequence to become manifest, for example producing a protein by activating the cellular functions involved in transcription and translation of a corresponding gene or DNA sequence. A DNA sequence is expressed in or by a cell to form an"expression product"such as a protein. The expression product itself, e. g. the resulting protein, may also be said to be"expressed"by the cell. An expression product can be characterized as intracellular, extracellular or secreted. The term"intracellular" means something that is inside a cell. The term"extracellular"means something that is outside a cell. A substance is"secreted"by a cell if it appears in significant measure outside the cell, from somewhere on or inside the cell.

The term"gene transfer"refers broadly to any process by which nucleic acids are introduced into a cell. Accordingly, the term"gene therapy"refers to the use of a gene transfer process for the purpose of treating a medical condition in a subject.

For the purposes of the present application, a subject or a patient may be an animal.

Preferably, the subject or patient is a human.

The term"transfection"or"transformation"means the introduction of a foreign nucleic acid into a host cell. Transfection or transformation may cause the host cell to express a gene or sequence which has been introduced to produce a desired substance, typically a protein coded by the introduced gene or sequence. The introduced gene or sequence may also be called a"cloned"or"foreign"gene or sequence and may include regulatory or control sequences, such as start, stop, promoter, signal, secretion, or other sequences used by a cell's genetic machinery. The gene or sequence may include nonfunctional sequences or sequences with no known function. The DNA or RNA introduced to a host cell can come from any source, including cells of the same genus or species as the host cell, or cells of a different genus or species.

The term"vector"means the vehicle by which a DNA or RNA sequence (e. g., a foreign gene) can be introduced into a host cell, so as to transform or transfect the host. Transformation or transfection may promote expression (e. g., transcription and translation) of the introduced sequence. Vectors may include plasmids.

Vectors typically comprise the DNA of a transmissible agent, into which foreign DNA is inserted. A common way to insert one segment of DNA into another segment of DNA involves the use of enzymes called restriction enzymes, which cleave DNA at specific sites (specific groups of nucleotides) called restriction sites, and DNA ligase which joins pieces of DNA, such as a restriction enzyme digested nucleic acid and a restriction enzyme digested plasmid vector, together. A"cassette"refers to a DNA coding sequence or segment of DNA that codes for an expression product that can be inserted into a vector at defined restriction sites. The cassette restriction sites are designed to ensure insertion of the cassette in the proper reading frame. Generally, foreign DNA is inserted at one or more restriction sites of the vector DNA, and then is carried by the vector into a host cell along with the transmissible vector DNA. A segment or sequence of DNA having inserted or added DNA, such as an expression vector, can also be called a "DNA construct."A common type of vector is a"plasmid", which generally is a self- contained molecule of double-stranded DNA that can readily accept additional (foreign) DNA and which can be readily introduced into a suitable host cell. A plasmid vector often contains coding DNA and promoter DNA and has one or more restriction sites suitable for inserting foreign DNA. Promoter DNA and coding DNA may be from the same gene or from different genes, and may be from the same or different organisms. A large number of vectors, including plasmid and fungal vectors, have been described for replication and/or expression in a variety of eukaryotic and prokaryotic hosts. Non-limiting examples include pKK plasmids (Clonetech), pUC plasmids, pET plasmids (Novagen, Inc., Madison, WI), pRSET or pREP plasmids (Invitrogen, San Diego, CA), or pMAL plasmids (New England Biolabs, Beverly, MA), and many appropriate host cells, using methods disclosed or cited herein or otherwise known to those skilled in the relevant art.

Recombinant cloning vectors will often include one or more replication systems for cloning or expression, one or more markers for selection in the host, e. g. antibiotic resistance, and one or more expression cassettes.

Accordingly, the term"sequence similarity"in all its grammatical forms refers to the degree of identity or homology between nucleic acid or amino acid sequences.

The term"sequence identity"or"identity"refers to exact matches between the nucleotides or amino acids of two nucleic acids or proteins, respectively, when these sequences are compared. For example, the degree of sequence identity between two nucleic acids may be determined by comparison of the amino acids of these proteins by use of the BLASTN or CLUSTALW sequence comparison algorithm.

Similarly, the amino acid sequences of two proteins may be determined by use of the BLASTP or CLUSTALW sequence comparison algorithm. The BLAST algorithms are publically accessible, at no cost, at the National Center for Biotechnology Information website (http://www. ncbi. nlm. nih. sov/). The CLUSTALW algorithm is publically accessible, at no cost, at the European Bioinformatics Institute website (http://www2. ebi. ac. ule/cluslalw/). The present invention includes HA-matrix systems which comprise nucleic acids which have a nucleotide sequence of at least 70% identity to the reference nucleotide sequence set forth in SEQ ID NO. 1 as well as nucleic acids which have a nucleotide sequence which encodes a protein whose amino acid sequence has at least 70% identity to the reference amino acid sequence set forth in SEQ ID NO. 2, wherein identity is determined using the BLASTN or BLASTP algorithms, respectively, where the parameters are selected to give the largest match between the respective sequences tested, over the entire length of the respective reference sequences.

However, in preferred embodiments, the level of identity mentioned above is greater than 70%, preferably 80% or greater, more preferably 90% or greater, even more preferably 95% or greater and most preferably 100%.

As used herein, the term"sequence homology"refers to both the number of exact matches and conserved matches between the amino acid sequences of two proteins. A conserved match is a match between two amino acids which are of similar biochemical classification. For example, in the context of a protein sequence comparison, a match of one amino acid with a hydrophobic side group with a different amino acid with a hydrophobic side group would be considered a conserved match. The classes which are generally known by those skilled in the art are as follows: hydrophobic (valine, leucine, isoleucine, methionine, phenylalanine, tryptophan, alanine, proline); hydrophilic (histidine,

lysine, arginine, glutamic acid, aspartic acid, cystine, asparagine, glutamine, threonine, tyrosine, serine, glycine); no charge/hydrophilic (cysteine, asparagine, glutamine, threonine, tyrosine, serine, glycine); aromatic (tryptophan, tyrosine, phenylalanine); negatively charged/hydrophilic (aspartic acid, glutamic acid); positively charged/hydrophilic (histidine, lysine, arginine).

Angiogenesis refers to the growth of new blood vessels anywhere in the body.

The term"induce"or"induction"refers to an increase by a measurable amount.

The term"derivative"refers to a compound obtained from a parent substance which includes the essential elements of said parent substance.

Dihydrazide refers to molecules having the formula: H2N-NH- C (=O)-R-C (=O)-NH-NH2; wherein R is a hydrocarbyl such as alkyl, aryl, alkylaryl or arylalkyl or R is heterohydrocarbyl which also includes oxygen, sulfur and/or nitrogen atoms in addition to carbon atoms. An alkyl may be branched or unbranched and contain one to 20 carbons or other carbon-sized atoms, preferably 2 to 10, more preferably 4 to 8 carbons or carbon-sized heteroatoms, such as oxygen, sulfur or nitrogen. The alkyl may be fully saturated or may contain one or more multiple bonds. The carbon atoms of the alkyl may be continuous or separated by one or more functional groups such as an oxygen atom, a keto group, an amino group, an oxycarbonyl group and the like. The alkyl may be substituted with one or more aryl groups. The alkyl may in whole or in part, be in form of rings such as cyclopentyl, cyclohexyl, and the like. These non-cyclic or cyclic groups described above may be hydrocarbyl or may include heteroatoms such as oxygen, sulfur, or nitrogen and may be further substituted with inorganic, alkyl or aryl groups including halo, hydroxy, amino, carbonyl, etc. Any of the alkyl groups described above may have double or triple bond (s). Moreover, any of the carbon atoms of the alkyl group may be separated from each other or from the dihydrazide moiety with one or more groups such as carbonyl, oxycarbonyl, amino, and also oxygen and sulfur atoms singly or in a configuration such as--S--S--,--O--CH2,--CH. 2--O--, S--S--CH2--CH2--and NH (CH2) n NH--. Aryl substituents are typically substituted or unsubstituted phenyl, but may also be any other aryl group such as pyrolyl, furanyl, thiophenyl, pyridyl, thiazoyl, etc. The aryl group may be further substituted by an inorganic, alkyl or other aryl group including halo,

hydroxy, amino, thioether, oxyether, nitro, carbonyl, etc. The alkylaryl or arylalkyl groups may be a combination of alkyl and aryl groups as described above. These groups may be further substituted as described above.

Therefore R can be hydrocarbyl, heterocarbyl, substituted hydrocarbyl substituted heterocarbyl and the like. The term hydrocarbyl as used herein means the monovalent moiety obtained upon removal of a hydrogen atom from a parent hydrocarbon. Representative of hydrocarbyl are alkyl of 1 to 20 carbon atoms, inclusive, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, undecyl, decyl, dodecyl, octadecyl, nonodecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl and the isomeric forms thereof ; aryl of 6 to 12 carbon atoms, inclusive, such as phenyl, tolyl, xylyl, naphthyl, biphenyl, tetraphenyl and the like; aralkyl of 7 to 12 carbon atoms, inclusive, such as benzyl, phenethyl, phenpropyl, phenbutyl, phenhexyl, napthoctyl and the like; cycloalkyl of 3 to 8 carbon atoms, inclusive, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and the like; alkenyl of 2 to 10 carbon atoms, inclusive, such as vinyl, allyl, butenyl, pentenyl, hexenyl, octenyl, nonenyl, decenyl, undececyl, dodecenyl, tridecenyl, pentadecenyl, octadecenyl, pentacosynyl and isomeric forms thereof. Preferably, hydrocarbyl has 1 to 20 carbon atoms, inclusive. The term substituted hydrocarbyl as used herein means the hydrocarbyl moiety as previously defined wherein one or more hydrogen atoms have been replaced with a chemical group which does not adversely affect the desired preparation of the product derivative. Representative of such groups are amino-, phosphino-, quaternary nitrogen (ammonium), quaternary phosphorous (phosphonium), hydroxyl, amide, alkoxy, mercapto, nitro, alkyl, halo, sulfone, sulfoxide, phosphate, phosphite, carboxylate, carbamate groups and the like.

Carbodihydrazides are preferred, however other dihydrazides are within the scope of the invention, such as sulfonodihydrazides and phosphonic dihydrazides. Accordingly, adipic dihydrazide refers to H2N-NH-C (=O)-(CH2) 4-C (=O)-NH-NH2.

Hydrophobic dihydrazides that are known to render HA more resistance to hyaluronidase degradation can be used in the formulation of the HA-matrix system so as to prolong the period of time over which nucleic acids are released.

Likewise, Hydrophilic dihydrazides (Vercruysse K. P., Bioconj Chem., 8: 686,1997) can be used to shorten the period of time over which nucleic acids are released.

The term"moiety"refers to a part, portion or subunit of a larger

compound.

The term"crosslinked"or"conjugated"refers to the attachment of two substances via any type of bond or force. A non-limiting list of specific means by which to crosslink two substances may include covalent bonds, ionic bonds or hydrogen bonds, van der Waals forces, ionic interactions and hydrophobic interactions.

The preparation of nucleic acids which may be used in the present invention may be accomplished by any means which yields nucleic acids of sufficient quality and purity so as to allow the successful practice of the invention.

Therapeutic Uses of the HA-matrix system The present invention may include embodiments wherein the HA- matrix system of the invention, may be administered to a subject, such as a human or animal, so as to cause a sustained transfer of the nucleic acid to cells of the subject. The use of the HA-matrix system of the invention in the treatment of any medical condition wherein a sustained transfer of nucleic acids to the cells of a patient would provide a therapeutic effect are within the scope of the present invention. Generally, the HA-matrix system of the invention is applied topically to the vicinity of the cells to which the transfer of the nucleic acids is to occur. Suitable locations for application of the HA-matrix system of the invention include sites which are internally or externally located in a subject's body. Internal sites may include internal organs, such as the heart, lungs or liver or other surfaces within the body of a subject. External sites may include the skin or other sites on the external surface of subject's body. An enhancement of wound healing may be the therapeutic effect attained. The HA- matrix system of the invention may include nucleic acids which encode a protein which, when contacted with the body of a subject, enhance wound healing or cause the production of a substance which enhances wound healing. Other proteins which may enhance wound healing may include, for example, epidermal growth factor (EGF). Enhancement of wound healing may be beneficial to subjects who suffer from skin lacerations, incisions, abrasions, punctures or other skin injuries. The HA-matrix system of the invention may also be useful in the treatment of internal injuries. Internal injuries which may be treated include damage to internal organs. Topical application of the HA-matrix system to, for example, an internal organ which has suffered physical damage may enhance the healing process of the organ.

Subj ects who have recently had invasive surgery or have sustained injuries as the result of an accident may find the HA-matrix system of the invention useful. In a preferred embodiment,

HA-matrix compositions including adipic dihydrazide derivatized hyaluronic acid, which is conjugated to plasmid DNA encoding the PDGF-J3 gene, are administered to a human patient for the purpose of enhancing the wound healing process in that subject.

The HA-matrix system of the invention provides a high degree of versatility in terms of the types of medical conditions they may be used to treat. The ability of the HA- matrix system to aid in wound healing may also be improved by substitution of PDGF-with another gene which encodes a protein capable of enhancing the wound healing process to a greater degree.

The following Examples are offered for the purpose of illustrating the present invention and are not to be construed to limit the scope of this invention. The teachings of all references cited herein are incorporated herein by reference.

SPECIFIC EXAMPLES OF THE INVENTION EXAMPLE 1: Chemical Derivatization of HA The methods according to Pouyani et al., U. S. patentJune 19,2000 5,652,347 were used to chemically derivatize Hyaluronic acid.

EXAMPLE 2: Formulation of an HA-Matrix and an HA-Film Using DNA as the Nucleic Acid (a tvpicalpreparation procedure) : The procedure shown in FIGURE 8 was followed in the formulation of the HA-matrix and HA-film. Approximately one milligram of DNA (pCMV 1 vector containing the p-galactosidase reporter gene, Clontech, Inc., Palo Alto, CA) was gently blended with 25 ml of 1% Hyaluronic Acid solution (Kraeber, Germany), it was then deposited in a mold. A HA-matrix was formed by lyophilization; whereas a HA-film was formed by slow dehydration at 37 °C overnight. The HA-film and HA-matrix (40 mg) was subsequently crosslinked in a solution of adipic dihydrazide (ADH, 25 mg) and ethyl-3 [3- dimethyl amino] propyl carbodiimide (EDCI, 18.5 mg, sigma Chemical Co. St. Louis, MO) dissolved in a solvent mixture of dimethyl formamide (DMF) and water (for film, a 80: 20 mixture of DMF andwater; for matrix, a 90: 10 mixture of DMF and water) for 4 to 6 hours. Upon completion of the crosslinking, the HA-film and HA-matrix was extracted with several portions of isopropyl alcohol in order to remove the DMF. Thereafter, the isopropyl alcohol was removed by aspiration.

DNA related variables (concentration of DNA) : After preparation of the HA-film and HA-matrix as described above, the relationship between the amount of DNA incorporated into the HA-film and HA-matrix and the corresponding DNA release characteristics were determined. Briefly, several batches of HA-film and HA-matrix were prepared by adding various quantities of DNA (0.1,0.5,1.0,2.0%) to the HA during the synthesis of the HA-matrices and HA-films. The data gained by evaluating the DNA release characteristics of these batches was helpful in determining the optimal amount of DNA to be used in the preparation of HA-matrices and HA-films.

Hyaluronic Acid related variables (amountlconcentration of HA): After preparation of the HA-film and HA-matrix as described above, the relationship between the concentration of HA solution used in preparing the HA-matrix and HA-film and the corresponding DNA release characteristics and HA degradation kinetics was investigated.

Briefly, several batches of HA-films and HA-matrices were prepared where in HA solutions of various concentrations (0.5,1.0,1.5%) were used to synthesize the HA- matrices and HA-films. The data gained by testing evaluating the DNA release characteristics and HA degradation kinetics of these batches was helpful in determining the optimal amount of HA to be used in the preparation of HA-matrices and HA-films.

Crosslinking related variables (amountlratio of HA, ADH, EDCI): The effect of varying the proportions of HA, adipic dihydrazide and EDCI in the preparation of the HA-matrix and HA-film on the susceptibility of HA to degradation and the effect of crosslinking upon HA susceptibility was also investigated. Experiments to evaluate these factors were performed by measuring the rate of release of DNA from the HA-martices and HA-films.

The relationship between the duration of crosslinking and the corresponding DNA release characteristics and HA degradation kinetics were also investigated. Briefly, different crosslinking durations (1,4,8,24 hours) are employed to prepare HA-matrix system. Matrices and Films of different HA degradation kinetics can be produced to have a wide array of DNA release characteristics.

Scanning electron microscopic (SEM) analysis of HA-matrices and HA- films: The consistency of the HA-matrix and HA-film, prepared as described above, was investigated by SEM analysis. The analysis revealed, as shown in FIGURE 1, that the HA-film compositions had a smooth consistency. As shown in FIGURE 2a the HA-matrix had a porous or lattice-like consistency. FIGURE 2b is a cross-sectional view of the HA- matrix which similarly indicates a porous surface.

EXAMPLE 3: Stabilitv of HA-Matrices in an Aqueous Environment The stability of HA-matrices in an aqueous environment over a period of 13 days was evaluated. Samples of HA-matrices and HA-films were suspended in a 0.02% ethidium bromide solution and analyzed at various times under an ultraviolet light. Visual inspection of the level of fluorescence in these suspensions was performed to measure the degree of disintegration and DNA diffusion of the HA-matrix and HA-film compositions at various times. These experiments evaluated the resistance of the matrix and film to disintegration as well as the resistance of the DNA included in the HA-matrix to diffusion.

FIGURE 3 depicts the results for the experiment involving the HA-films and FIGURE 4 depicts that of the HA-matrices. In each FIGURE (a) depicts the results of each experiment at 0 hours, (b) 4 days and (c) 13 days. In the experiment of FIGURE 4, vials 1, 2 and 3 contained independently synthesized samples of the matrices wherein sample 3 had a higher degree of crosslinking than #2 and #2 had a higher degree of crosslinking than #1. In the experiment of FIGURE 3, the crosslinking of the HA-film in vial 1 had a

higher degree of crosslinking than that in vial 2. The control vial contained HA-film or HA-matrix without DNA. The fluorescence depicted in FIGURE 4A indicates that DNA had begun to diffuse in each sample; FIGURE 4B indicates that 1 and 2 are beginning to physically disintegrate and 3 remains largely intact; FIGURE 4C indicates that 1 has further disintegrated wherein 2 has completely disintegrated, and 3 has begun to disintegrate. These experiments indicate that HA-films and HA-matrices which are highly crosslinked are more resistant to disintegration and DNA diffusion than compositions wherein there is less crosslinking.

EXAMPLE 4: Sustained Release of DNA from the DNA-HA Matrix HA-films and HA-matrices prepared by the method described in EXAMPLE 2 were tested for controlled release kinetics. A sample of the HA-films and HA-matrices were incubated in a container with lml of phosphate buffer and saline (PBS) containing hyaluronidase, at a concentration of 10units/ml. At various time intervals, the PBS/hyaluronidase mixture was evacuated from the container and replenished with a fresh aliquot of PBS/hyaluronidase buffer. The mixtures which were evacuated from the container were tested for the presence of DNA. The DNA obtained during this controlled release study was tested for its ability to transfect chinese hamster ovary (CHO) cells in culture. Theoretical calculations revealed that between 8% and 11% of DNA were released from the DNA-HA film and matrix, respectively, after 12 days. Results out to 35 days are illustrated in FIGURE 9.

EXAMPLE 5: Electrophoretic Motility Analyses Electrophoretic motility analyses (FIGURE 5) were performed on the DNA samples collected during the course of the sustained release study (Example 3) using phosphate buffer containing the enzyme hyaluronidase. FIGURE 5 depicts a representative result. Lanes 1 and 2 are the marker and the DNA used to prepare the HA- film and HA-matrix, respectively. Lanes 3,4,5 and 6 are the DNA samples obtained from the sustained release study. The distinct bands demonstrate that the DNA eluted from the films and matrices during the course of the controlled release study are structurally intact.

EXAMPLE 6: Electrophoretic Motility Analyses of DNA-HA Fragments Electrophoretic Motility Analysis was used to determine whether the DNA is covalently attached to the derivatized HA or entrapped in the HA-film or HA-matrix.

Both the HA-film and HA-matrix were incubated in 1 mM Tris-EDTA (ethylenediamin tetraacetic acid) buffer (Sigma, St. Louis, MO) for hydration (FIGURE 6). Both samples were pulverized (using a microspatula in a microcentrifuge tube) and a small fraction of each (containing fragments) was loaded into an agarose gel (using standard protocol, FMC Bioproducts, Rockland, ME). FIGURE 6 depicts a representative result. Lane 1 and 2 are the markers and DNA used to prepare the HA-film and HA-matrix, respectively. Lanes 3, 4,5 and 6 are DNA samples from representative HA-film and HA-matrix formulations. A large proportion of the DNA remains in the well (not migrated), this indicates that the DNA covalently conjugated to the Hyaluronic Acid does not migrate through the agarose gel due to the large size of the HA-film and HA-matrix. This is the result indicates an effective covalent attachment of the DNA to the derivatized HA.

EXAMPLE 7: Transfection of Chinese Hamster Ovarian (CHO) Cells The functionality of the plasmid DNA (encoding pCMV 1 p-galactosidase reporter gene (Clontech, Inc., Palo Alto, CA)) incorporated into both the HA film (3.1 mg with 0.5% DNA loading) and the HA-matrix (3.3 mg with 0.5% DNA loading) prepared as described above were assessed with a gene transfer study using CHO cells. Briefly, both HA films and HA-matrices were placed in cell culture wells, for a duration of 48 hours, while the CHO cells were growing. Both HA film and HA-matrix used in this experiment were designed to release DNA on a prolonged basis of about 48 hours. Cytochemical analyses by exposing the cells to X-GaITM indicator (Gibco Life Technology, Grand Island, NY) were performed after incubation. Cells expressing p-galactosidase turned blue in the presence of X-gal. FIGUREs 7a (cells exposed to the HA-matrix) and FIGURE 7b (cells exposed to the HA-film) depict representative areas in the cell culture dishes incubated with the HA-matrix and HA-film. Overall, approximately 3-5% of the cells were transfected using both film and matrix.

Example 8: DNA Content of Films and Samples (Thiazole Orange Assay) The DNA component of the HA-films and HA-matrices described above

was released from its covalent attachment to the derivatized hyaluronic acid by treatment with hyaluronidase. Subsequently, the quantity of DNA which was released was determined by a fluorometric assay using Thiazole Orange (Aldrich Chemical, Milwaukee, WI) an intercalating dye (Wadhwa M. S., et al., Bioconjugate Chem 6: 283-291,1995).

Fluorescence of Thiazole Orange intercalated DNA was measured at an excitation wavelength of 486 nm and an emission wavelength of 530 nm. (Wadhwa M. S., et al., Bioconjugate Chem 6: 283-291,1995) The amount of DNA can readily be determined by referencing the result against a standard plot prepared previously. A standard 260nm/280nm UV spectrophotometric assay can also be used to determine the DNA levels in samples with high DNA concentrations. The data gathered from these experiments indicated the quantity of DNA associated with the HA-films and HA-matrices of the invention.

Example 9: Uronic Acid Assav When applied to the body of a subject, one possible mode of HA breakdown, which leads to release of the nucleic acids, is by the action of hyaluronidases.

Therefore, the stability of the HA-matrix and HA-film to hyaluronidase degradation was of interest. This was determined in the following experiments wherein the breakdown of HA was monitored by uronic acid assay: 2 ml of 0.025M sodium tetraborate (Sigma Chemical Co., St. Louis, MO) (in concentrated sulfuric acid (Aldrich Chemical, Milwaukee, WI) was added to a uronic acid (hyaluronic acid) sample at 4 °C, then incubated in boiling water for 10 minutes, followed by chilling at 4°C. After adding 80 p1 of 0.125% carbazole (Sigma Chemical, St. Louis, MO) (in methanol (Aldrich Chemical, Milwaukee, WI), the mixture was incubated in boiling water for an additional 15 minutes. The optical density of the samples was measured at a wavelength of 530 nm. The sample uronic acid content was determined by referencing the result against a standard plot prepared previously.

Example 10: Production/Characterization of Reporter Gene (ß-galactosidase ! p-galactosidase [LacZ] plasmid DNA (pCMV-beta-gal) was obtained commercially from Clonetech, Inc. (Palo Alto, CA).

Preparation of lLacZl plasmid DNA : [LacZ] plasmid DNA was inserted

into competent E. Coli cells and produced in quantity using the EndoFreeTM plasmid kit (Qiagen Inc., Valencia, CA) following established protocols (Caplan, J. J., Gen Therapy, 1: 139-147,1994, Schleef et al."Biotechniques 14: 544,1993). The purity, quality and quantity of the [LacZ] plasmid obtained was assessed with methodology described below.

Characterization (qualitative and quantitative) of Plasmid DNA : The quality of plasmid DNA produced was determined by agarose gel electrophoresis using ethidium bromide as a staining agent. Plasmid DNA which was restriction enzyme (EcoRI) digested, was referenced against standard DNA markers for proper identification of the bands which developed on the agarose gel. The quantity of DNA produced was determined by a fluorometric assay using Thiazole Orange as an intercalating dye.

Fluorescence of Thiazole Orange intercalated DNA was measured at an excitation wavelength of 486 nm and an emission wavelength of 530 nm. (Wadhwa m. S., Bioconjugate Chem 6: 283-291,1995). The amount of DNA was determined by referencing the result against a standard plot prepared previously. A standard 260nm/280nm UV spectrophotometric assay was used to determine the DNA levels in samples with high DNA concentrations.

EXAMPLE 11: Characterization of in vitro Sustained Transfer of a Reporter Gene (ß-galactosidase ! and PDGF-B in CHO Cells.

The effectiveness and longevity of a PDGF-p-FLAG fusion gene delivered from an HA-film and HA-matrix in both CHO (fibroblast cell) and HUVEC (endothelial cell) cultures was evaluated. FLAG was employed in this experiment as a tracking marker. The PDG''-j3 gene including restriction sites, which was cloned into the pFLAG- CMV-5a plasmid, in the construction of PDGF-P-FLAG, is set forth in SEQ ID NO. 3.

FIGURE 11 is a diagram of the plasmid into which PDGF (3 is inserted. Fibroblasts, similar to CHO cells, appear in a wound within 2 to 3 days (Stadelmann WK., Am. J.

Surg. 176 (Suppl 2A): 26S-28S, 1998). Angiogenesis which involves vascular endothelial cells, similar to HUVEC cells, accompanies the fibroblastic phase of the wound healing process and is essential, since new capillary growth must accompany the fibroblasts, as they advance into the wound site to provide their metabolic needs. Therefore, the ability of the HA-matrices and HA-films to transfect CHO and HUVEC cells in a stable manner is significant. Successful transfection of cells resulted in the expression of p-galactosidase

or PDGF-p-FLAG fusion protein (SEQ ID NO. 4). The transfection efficiencies/effectiveness of these HA-films and HA-matrices and their corresponding longevity of DNA release were evaluated in these experiments. Thereafter, the effectiveness of [FLAGTM marker + PDGT-J3] fusion gene constructs was determined in both CHO and HUVEC cultures. A FLAGTM marker was used in order to distinguish between PDGF-P from the HA-matrices and HA-films from that of the endogenous PDGF-P. A Human CMV promoter/enhancer was used to drive expression of the genes used in these experiments.

Reporter Gene Construct : ß-galactosidase [LacZl under the control of human cytomegalovirus (CMV) enhancer/promoter was used as a model reporter gene construct to evaluate the magnitude and mechanism of cell transfection and gene expression in both CHO and HUVEC cells. The pCMV 1 vector was obtained from a commercial source (Clontech, Inc., Palo Alto, CA). The extent of ß-galactosidase expression in cell cultures was quantified. Episomal expression of the gene resulted in the production of p-galactosidase.

Cell Transfection: CHO and HUVEC Cell Culture with lacZ : Chinese Hamster Ovarian cells (CHO) and Human umbilical vascular endothelial cell (HUVEC) were used as model cell cultures to evaluate the degree of episomal transfection, gene expression and enzyme activity of the- [CMV enhancer/promoter]- [LacZ]- reporter gene construct (released from the HA film preparations). HA-films and HA-matrices were placed in cell culture medium. The HA-film and HA-matrix equivalent of 10,20,50 and 100, ug of plasmid DNA per culture plate was added to define the operating range for the cell culture system. For comparison, a standard Lipofectamine reagent mediated DNA transfection was performed as a positive control. At the conclusion of the study, ß- galactosidase gene expression of the transfected cells was evaluated.

Analysis of ß-galactosidaseActivity: (Cytochemical analysis) : The transfected cells from culture were fixed for 10 minutes with a 0.5% glutaraldehyde solution (in phosphate buffered saline). The cells were rinsed and incubated for 10 minutes (at room temperature) with a 1 mM MgC12 solution (in pH 7.4 phosphate buffered saline).

Subsequently, the cells were stained with a X-galTM staining solution (1 mg X-galTM per ml, 5 mM K3Fe (CN) 6,5mM K4Fe (CN) 6,1 mM MgC12 in pH 7.4 phosphate buffered saline) for 5 hours. Cells expressing (3-galactosidase turned blue in the presence of X-gal indicating successful transfection and reporter gene expression.

En :, vvne assav: The P-galactosidase enzymatic activity of the transfected HUVEC and CHO cell lysates was detected by Galacto-Light Plus chemilluminescent reporter system with a luminometer (Kunitz M., J. Gen. Physiol., 33: 349-362, 1950). The chemluminescence levels in samples were compared after being normalized for their sample protein contents.

Immunohistochemical analvsis: Since the enzyme assay described above underestimates the extent of p-galactosidase cell transfection, immunohistochemical analysis was performed (Couffinhaul, et al., Human Gene Therapy, Vol. 8 p. 929-934 (1997)). Briefly, transfected cells were fixed with 10% neutral buffered formalin followed by treatment with ammonium chloride, hydrogen peroxide and 2% gelatin (in phosphate buffered saline) to quench extraneous aldehyde, block endogenous peroxidase activity and block non-specific protein binding, respectively. A p-galactosidase antibody was applied followed by an appropriate secondary antibody conjugated to a marker (fluorescent or horseradish peroxidase).

The longevity of DNA delivery by the HA film and HA-matrix in vitro was defined by the duration of p-galactosidase expression in both CHO and HUVEC cells. A CHO cell transfection study was performed using DNA samples collected during the course of the controlled release study. Samples gathered from Days 2,5,9,14, and 19 were used and the results are summarized in TABLE 1.

TABLE 1A Longevity of DNA Release from DNA-HA Film and the Magnitude of CHO Cell Transfection Time (Day) Relative Level of Transfection 2++/+ 5++/+ 9+++/++ 14 +++/++ 19 +++/++ 24+++/++ 30++ 35 ++/+ 39 ++ 46 ++ 53+++ TABLE 1B Longevity of DNA Release from DNA-HA Matrix and the Magnitude of CHO Cell Transfection Time (Day) Relative Level of Transfection ++++ +++/++ 9++++ 14 +++++ +++++/++++ 24 ++++/+++ 30 +++++ 35 +++ 39++++/+++ 46 + Low = + Moderate = +++ High = +++++

Formulation of HA-films and HA-matrices with different DNA loadings, release kinetics and release duration is one embodiment of the invention. The results derived from the in vitro sustained DNA release experiments (EXAMPLE 4) are largely in accord with the performance of the HA-matrices and HA-films in cell culture. The longevity of gene transfer using our systems includes the duration of the DNA delivery from the film or matrix to the host cell plus the duration of plasmid DNA expression in the cell.

Polylysine complexes with DNA and causes condensation from a long circular strand configuration into a highly compacted particulate state, (Wagner E, et al., PNAS 88: 4255-4259,1991, Hud, NV, et al., PNAS 92: 3581-3585,1995, Laemmli UK, PNAS 72: 4288-4292,1975, Sosnowski BA, et r1., J Biol Chem 271: 33647-33653,1996) and thus render the DNA some degrees of protection from endonuclease degradation (Fritz J. C., et al., Hum. Gen. Ther. 7: 1395-1404,1996). Condensation of DNA with polylysine has also been shown to enhance plasmid transfection. (Ciftci K., et al., Pharm. Res.

13 (9): S390.1996) Alternatively, the liposome technology as described in patent number 5,874,105 could be employed as an adjunctive agent to protect and enhance DNA transfection. One could readily assess the protection using standard techniques such as DNA protection study (in the presence of serum endonuclease) (R. C. Adami, et al., J. of Pharmaceutical Science, 87: Vol 5., p 678-683,1998).

PDGF-/3-FLAG transfection W cell cultures (CHO and HUVEC): The plasmid DNA containing the cDNA encoding Human Platelet Derived Growth Factor-ß (PDGF-J3) gene was used as the therapeutic gene in conjunction of the FLAGTM marker system for tracking PDGF-P expression (human PDGF-ß cDNA (pSMlPDGF-ß vector, ATCC #57050, (Manassa, VA). Because of the presence of the membrane retention sequence at the C-terminal end of the polypeptide, PDGF-p expressed from full-length cDNA was not secreted; a 3'-truncated form of the human PDGF-0 cDNA (pSMIPDGF-P vector, ATCC #57050, (Manassa, VA) prepared in the lab was used to prepare all therapeutic gene constructs to achieve secretion. The sequence of the truncated PDGF J3 gene including restriction sites which were cloned into the expression vector is set forth in SEQ ID NO. 5 and the corresponding truncated PDGF-p protein including the FLAG tag (DYKDDDK) is set forth in SEQ ID NO. 6. The truncated PDGF-p gene without

restriction sites is set forth in SEQ ID NO. 1 and the corresponding protein without the FLAG tag is set forth in SEQ ID NO. 2. The 3'-truncated form is produced following published methodology (Norton et al., Ann Surg 224 (4): 555-562,1996).

Marker]FusionGeneConstruct:APDGF-ß-[FLAGTMTracking Human Platelet Derived Growth Factor (PDGF-P) gene under the control of human cytomegalovirus (CMV) enhancer/promoter was utilized as the therapeutic gene construct. The FLAGTM system (Sigma Chem. Co., St. Louis, MO) based on the fusion of an octapeptide FLAGTM sequence (Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Lys) to a cloned gene was used as the marker for PDGF expression. The pCMV-FLAG-1 variation designed for secretion of the FLAGTM fusion protein was utilized. The 24 base pair DNA FLAGTM coding sequence was fused with PDGF- (3 when the gene was cloned into the pFLAG- CMV-5 plasmid. The recombinant protein expressed was tagged with the FLAGTM octapeptide sequence to form a fusion protein according to the method of Chubert et al., BioTechniques 20: 136-141,1996).

Cell transfection and the longevity o,'DNA release from DNA-HA film/matrix: CHO and HLTVEC cell cultures were used to assess the efficacy of- [CMV enhancer/promoter]- [FLAGTM + PDGF-ß]-therapeutic gene construct in HA-film and HA-matrix formulations. Effective transfection renders the cells able to produce PDGF-p- FLAGTM octapeptide fusion protein. The longevity of DNA release and cell transfection from the HA-film and HA-matrix was then evaluated.

Detection of PDGF-ß gene expression in vitro : The FLAG octapeptide sequence on the PDGF-ß-(FLAG octapeptide) fusion protein was proteolytically cleaved with enterokinase (supplied by the FLAGTM kit) which is specific for the (Asp- Asp-Asp-Asp-Lys) pentapeptide sequence on the FLAGTM (Asp-Tyr-Lys-Asp-Asp-Asp- Asp-Lys) octapeptide. Anti-FLAGTM Monoclonal Antibodies (Sigma Chem. Co., St.

Louis, MO) were used to detect the FLAGTM octapeptide. The presence of FLAGTM octapeptide also indicated the expression of PDGF-ß and thus effective transfection in vitro. The procedure established by Chubert et al. was followed (Chubert et al., BioTechniques 20: 136-141,1996).

CHO and HUVEC cell cultures were transfected by the therapeutic gene construct- [CMV enhancer/promoter]- [FLAGTM + PDG'F-/3]-. With the use of enterokinase (supplied by the FLAGTM kit), the FLAGTM octapeptide was detected with FLAGTM Monoclonal Antibodies. The detection of the FLAGTM octapeptide strongly indicated that the transfection of the fibroblast and endothelial cells was successful and it also indicated that the production of FLAGTM + PDGF-P-fusion protein was occurring in the host cells. The longevity of DNA delivery by the DNA-HA film/matrix system in vitro was defined by the duration of expression of [FLAGTM + PDGF-p]-fusion protein in both CHO and HUVEC cells.

CHO and HUVEC Cell Culture: Chinese Hamster Ovarian cell (CHO) and Human umbilical vascular endothelial cell (HUVEC) were used as model cell cultures to evaluate the induction cellular proliferation by HA-matrix and HA-film preparations with the therapeutic PDGF-/3 gene construct. A HA-matrix or HA-film was placed in cell culture medium and at the conclusion of the study, the efficacy evaluated colorimetrically by MTT assay (Hagerman et al., J. Immunol. 145: p. 3087,1990). The degrees of cell proliferation indicated the effectiveness of the DNA-HA film/matrix.

Assessment of cell proliferation assay: Degrees of cell proliferation were assessed with MTT assay. MTT assay kits were available from various commercial sources. Briefly, the degree of cell proliferation of HA-matrix or HA-film-treated groups were compared to that of the controls. This was used as an indication of the effectiveness of the PDGF-/3 gene delivered from DNA-HA film/matrix.

EXAMPLE 12: In Vivo Gene Transfer by DNA-HA Matrix HA matrix with a 0.5% DNA (encoding the p-lactamase reporter gene) loading/content was implanted into pig subdermal (endodermal) biopsy wounds. After 12 days, the implant site was excised and assessed for p-lactamase expression.

Representative microscopy sections are depicted in FIGURE 10. The blue/dark spots of the specimen indicate a very high level of P-lactamase expression. These results are a highly significant indication of the ability of the HA matrices of the invention to transfer genes to the cells of a subject.