Wound contraction is the process which diminishes the size of a full-thickness open wound, especially a full-thickness burn. The tensions developed during contracture and the formation of subcutaneous fibrous tissue can result in deformity, and in particular to fixed flexure or fixed extension of a joint where the wound involves an area over the joint. Such complications are especially prevalent in burn healing.

Scar contracture is the result of the contractile process occurring in a healed scar, and often results in an undesirable, fixed, rigid scar that can cause functional or cosmetic deformity. In general, wound contraction occurs in an incompletely epithelialised defect, while scar contracture occurs in an epithelialised covered defect. The term"wound contracture"is used herein to cover both wound contraction and scar contracture.

Wound contraction and scar contracture are reviewed in detail by Ross Rudolph, Jerry Vande Berg and H. Paul Ehrlich in Wound Healinq : Biochemical and Clinical Aspects, I. K. Cohen, R. F. Diegelmann and W. J. Lindblad Eds, W. B. Saunders Company, pages 96-114, the entire content of which is incorporated herein by reference.

The deleterious effects of contracture can also occur underneath the skin surface or involve deep vital organs. Well-known examples are contraction of the palmar fascia in Dupuytren's contracture and the contraction of a capsule around a silicone breast implant, and certain complications of cardiac pacemaker implants.

In addition, contracted fibrotic scar bundles within the cirrhotic liver may compress intrahepatic vessels and contribute to portal hypertension. Other viscera can

undergo contractures, such as in duodenal ulcer stricture, the contracture of cardiac valves in rheumatic heart disease, and urethra strictures in trauma.

Fibroblasts and myofibroblasts have been implicated in the mechanism of wound contraction. It has been suggested to use substances or procedures which interfere with fibroblast and myofibroblast mobilisation, migration, adhesion or multiplication for the inhibition of wound contracture. For example, high doses of cortisone or related steroids have been shown to suppress fibroblast proliferation, and thereby inhibit wound contracture. Unfortunately, steroids given in such high doses give unacceptable side effects in clinical practice.

Cellular poisons such as cyanide and dinitrophenol, have also been reported to inhibit wound contraction. Likewise, drugs which inhibit smooth muscle contraction have been reported to inhibit wound contraction, for example, colchicine, vinblastine and phenyltoin.

In practice, control of wound contracture is presently mainly mechanical and surgical. The surgeon may wish to facilitate wound contraction in some situations and to inhibit it in others. The following approaches are used to reduce undesirable scar and wound contraction: (1) prolonged splinting, (2) range of motion exercises, (3) pressure, (4) full-thickness skin grafting, and (5) judicious planning of surgical procedures.

It has also been found that an adherent dressing, such as untreated gauze, can delay, but does not prevent contracture. In contrast, certain synthetic films such as nylon applied to the wound surface before active contracture has started can inhibit contracture.

It has been found that application of a full-thickness skin graft to an open wound before wound contracture commences is effective to prevent wound contracture.

However, significant problems are associated with skin grafting including cost, the source of grafting skin, rejection of the graft, secondary infection, and associated surgical risks. Severe contracture is still observed when thin or meshed skin grafts are applied instead of full-thickness skin grafts.

US-A-4957902 describes the inhibition of wound contracture by application to the wound of peptides having an amino acid sequence Arg-Gly-Glu and N-terminal and C-terminal derivatives thereof.

It has now been found that certain other peptides display promising activity in vitro that is indicative of ability to prevent or reduce wound and scar contracture.

Accordingly, the present invention provides the use of a peptide or peptide derivative having the sequence X-NH-Gly-Pro-Ala-Gly-CO-Y, wherein X is H or a pharmaceutical acceptable N-terminal group, and Y is OH or a pharmaceutical acceptable C-terminal group, for the preparation of a medicament for use in the treatment or prevention of wound contracture.

Earlier patent application GB-A-2321191 describes the use of such peptides for the treatment of chronic wounds, such as diabetic ulcers.

It has now been found by means of the in vitro fibroblast populated collagen gel contraction model described in detail below under procedure 1 that the tetrapeptide Gly-Pro-Ala-Gly is surprisingly effective to inhibit collagen gel contraction. This effect was observed with both neonatal and foetal fibroblasts. It was further found that the tetrapeptide inhibited the stimulatory effect of certain growth factors on fibroblast populated collagen gel contraction. These results provide a clear indication that the tetrapeptides are likely to be effective to reduce wound contracture in vivo. Furthermore, these results indicate that a number of derivatives of the tetrapeptide when used as a dressing are likely to reduce wound contracture, either due to analogous activity or becouse the derivative breaks down gradually in vivo in the wound bed to the tetrapeptide.

Preferably, X is a pharmaceutical acceptable N-terminal group that is hydrolyzed or otherwise metabolized to H under physiological conditions. Preferably, Y is a pharmaceutical acceptable C-terminal group that is hydrolyzed or otherwise metabolized to OH under physiological conditions.

For example, X may be a C1-C8 alkyl group or a C1-C8 alkylcarbonyl group. In other preferred embodiments, X may be an amino acid or a short peptide chain, provided that the total peptide length of the active compound is no more than 12 amino acids, preferably no more than 6 amino acids.

Likewise, Y may be a C1-C8 alkoxy group or a C1-C8 alkylamino group. In other preferred embodiments, X may be an amino acid or a short peptide chain, provided that the total peptide length of the active compound is no more than 12 amino acids, preferably no more than 6 amino acids.

Preferably, X and Y are both H, i. e. the tetrapeptide is not derivatized.

The definition of the active compound given herein encompasses all active salts and stereoisomers thereof.

Preferably, the medicament contains from 0.0002% to 10% by weight of the peptide or peptide derivative, more preferably from 0.0005% to 1%, still more preferably from 0.001% to 0.1%, and most preferably from 0.002% to 0.01%.

Preferably, in the use according to the present invention, the medicament comprises a solid wound dressing for topical application. For example, the tetrapeptide or derivative thereof may be dispersed in or on a solid wound dressing material such as a woven or nonwoven fabric, a film or a sponge that is applied to the surface of the wound to reduce contracture.

The wound dressing material may be a material that is absorbable in vivo. For example, a synthetic or semi-synthetic polymer such as polylactide/polyglycolide, or oxidized regenerated cellulose (ORC). The material may comprise a biopolymer such as collagen, gelatin, an alginate, chitosan, hyaluronic acid, guar gum or xanthan gum. In certain preferred embodiments of the present invention, the peptide is dispersed in a matrix of oxidized cellulose complexed with collagen to form structures of the kind described in W098/00180 and W098/00446, the

entire contents of which are expressly incorporated herein by reference. For example, the oxidized cellulose may be in the form of milled ORC fibres that are dispersed in a freeze-dried collagen sponge. This provides for sustained release of the oxidized cellulose to the wound, together with certain therapeutic and synergistic effects arising from the complexation with collagen. Finally, ORC itself has the property of reducing wound contracture, as demonstrated in GB 9923291.0 referred to above.

In other preferred embodiments, the use according to the present invention. provides a medicament in the form of an ointment or gel for topical application to a wound comprising the active material in a pharmaceutically acceptable carrier.

Suitable carriers include : hydrogels containing cellulose derivatives, including hydroxyethyl cellyulose, hydroxymethyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, and mixtures thereof, and hydrogels containing polyacrylic acid (Carbopols). Suitable carriers also include creams and ointments used for topical pharmaceutical preparations, e. g. creams based on cetomacrogol emulsifying ointment. The carriers may include alginate (as a thickener or stimulant), preservatives such as benzyl alcohol, buffers to control pH such as disodium hydrogen phosphate/sodium dihydrogen phosphate, agents to adjust osmolarity such as sodium chloride, and stabilizers such as ethylene diamine tetra acetate (EDTA).

The dressings comprising the peptide may be sterilized, for example by gamma- irradiation, and packaged in a microorganism-impermeable container.

The medicaments provided by the present invention may be applied to a wound or a burn shortly after the wound or burn has been inflicted.

Preferably, the medicaments provided by the present invention are applied from two to seven days after the wound or burn has been inflicted, since this is when contracture of the wound or burn is thought to start. In other preferred embodiments the medicaments provided by the present invention are applied to the wound or burn after epithelialisation is complete, for the reduction of scar

contracture. Preferably, the medicaments provided by the present invention are applied both before and after epithelialisation of the wound is complete.

Preferably, the application is continued for at least one week, more preferably at least two weeks, still more preferably at least four weeks, and most preferably six weeks or more. This reflects the fact that the tissue remodelling results in wound contraction and scar contracture is a longer-term process that typically begins some time after the onset of wound healing, and continues after epithelialisation of the wound is complete.

Preferably, the wound is a granulating wound. Preferably, the wound is a full- thickness wound or burn. Preferably, the full thickness area of the wound is at least 5cm2, more preferably at least 10cm2, and most preferably at least 20cm2.

Preferably, the wound is a burn. The medicaments are also expected to be useful for the reduction of contracture in the region of breast implants or cardiac pacemaker implants.

Accordingly, in a further aspect, the present invention provides a method for inhibiting wound contracture comprising the steps of: (a) providing a pharmaceutical acceptable composition including as the active principle a peptide or peptide derivative having the sequence X-NH-Gly-Pro-Ala-Gly-CO-Y, wherein X is H or a pharmaceutical acceptable N-terminal group, and Y is OH or a pharmaceutical acceptable C-terminal group; and (b) administering a therapeutical effective amount of the pharmaceutically acceptable composition to an individual in need thereof.

It will be appreciated that the present application can also be useful in the treatment of internal wounds. Administration may be by any means that facilitate the contracture-inhibiting effect of the peptide or peptide derivative. Preferably, the administration is topical. Preferably, the medicament is manufactured in accordance with any of the preferred embodiments of the use according to the invention, as enumerated above.

Particular embodiments of the present invention will now be described further, by way of example, with reference to the accompanying drawings, in which:- Figure 1 illustrates the effect various concentrations of the tetrapeptide Gly-Pro- Ala-Gly on dermal fibroblast populated collagen gel contraction, the measurements being carried out in the presence of 10ng/ml of platelet derived growth factor (PDGF), (a) at time T=day 3, (b) at time T=day 6, and (c) at time T=day 9.

Procedure 1 The inhibitory effect of the tetrapeptide Gly-Pro-Ala-Gly on fibroblast populated collagen gel contraction was determined by a method similar to that described in US-A-4957902.

Briefly, fibroblast populated collagen gels were prepared as follows : neonatal fibroblasts (HSF 43 SK supplied by ATCC) were grown to confluency in 10% Fetal Bovine Serum (FBS)/Dulbecco's Modified Eagles Medium (DMEM). The cells were harvested using 0.05% trypsin/EDTA, counted and centrifuged to remove trypsin solution. The cells were resuspended at a cell density of 106 cells/ml.

The following mixture was then made up: 8mls 10% FBS/DMEM, 4mis of the cell suspension, and 4mis of aqueous VITROGEN collagen supplied by Collagen Corporation, Palo Alto, CA (concentration 4mg/ml). The mixture was then distributed at 0.5mi/well in a 24-well plate and allowed to gel at 37°C for 1 hr.

Once the gels had set they were rimmed with a sterile pipette tip to enable them to contract freely, and then additional 0.5ml aliquots of FBS/DMEM were added carefully to each well. The aliquots additionally contained the following active ingredients: None (negative control) 10 ng/ml Platelet Derived Growth Factor (PDGF, positive control) 30 ug tetrapeptide

3 ug tetrapeptide 1.5 pg tetrapeptide 200 ng tetrapeptide 150 ng tetrapeptide 5 ng tetrapeptide When present, the tetrapeptide was prepared in accordance with Example 1 hereinbelow at a concentration of 0.5mg/ml, giving a final concentration in the gels of 0.165mg/ml. All solutions were sterile filtered. Each growth factor was incubated for 1hr at 37°C in the stock solution before its addition to the rimmed collagen gels.

Contraction of the collagen gels was measured by taking photographs of each gel over 10 days, and measuring the gel area from the photographs. The results can be summarised as follows, with reference to the Figures.

Referring to Figure 1 (a), this bar chart shows the collagen gel area at t=3 days for the collagen gels populated with fibroblasts. It can be seen that all of the gels have shrunk significantly due to fibroblast proliferation in the gel. The test gels containing the tetrapeptide appear to have shrunk slightly less that the negative control gel, but this may not be statistically significant.

Referring to Fig. 1 (b), this shows the areas of the gel samples of Fig. 1 (a) at t=6 days. It can be seen that all of the gels have shrunk further due to fibroblast proliferation in the gel. It can also clearly be seen that the samples containing higher concentrations of the tetrapeptide exhibit a statistically significant reduction in contracture of the gel area after 6 days compared to the samples that contain less than 3 ug of the tetrapeptide. The same effect is even more marked at t=9 days, as shown in Fig. 1 (c).

Example 1 The tetrapeptide Gly-Pro-Ala-Gly was prepared in a fully automated Applied Biosystems 430A peptide synthsiser. The Fmoc/tBu based method of peptide synthesis was used, which involves the use of the base labile 9- fluorenylmethoxycarbonyl amino protecting group in conjunction with acid labile side protection and peptide-resin linkage. The peptide was synthesized using Fmoc-glycine functionalized 4-alkoxybenzyl alcohol resin (Wang Corporation), and all amino acids were incorporated using double coupling cycles. Each synthetic cycle involved : (1) treatment with acetic anhydride to cap any free amino groups prior to amine deprotection, (2) Fmoc removal by treatment with the organic base piperidine, and (3) coupling of the next amino acid in the sequence. In this way the desired peptide was built up from the C to N terminus. The peptide was then cleaved from the resin with simultaneous removal of side chain protecting groups by treatment with a mixture of TFA/ethanediol/triisopropylsilane/thioanisole and water for 3 hours at room temperature. The resin was then removed by filtration, the TFA evaporated and the peptide isolated by precipitation with diethyl ether and filtration. The crude peptide was then purified by reverse phase HPLC and lyophilized. Laser desorption mass spectroscopy and analytical HPLC were carried out to confirm purity of the peptide.

Example 2 A solid, bioabsorbable collagen/ORC sponge dressing containing the peptide of example 1 is prepared as described in W098/00180. Briefly, the freeze-dried collagen prepared as described in US-A-4614794 or US-A-4320201 is re- suspended in 0.05m acetic acid at a concentration of 10mg/ml. Milled ORC powder (milled SURGICEL cloth) is added to the suspension at a ratio of 1: 3 ORC: collagen and homogenized using a Waring blender on low speed for 3x30 seconds. The peptide is then added to the suspension at a concentration of lpg/ml. The complex suspension is degassed in a vacuum oven for 10 minutes, and is then poured to a depth of 3mm into a tray and blast frozen. The frozen suspension is then either freeze-dried and dehydrothermally cross-linked using a programmable freeze-drier with a temperature ramping facility, or it is dried using a

solvent drying process as described in US-A-2157524. The dressing is suitable for application to a large-area burn to reduce contracture Example 3 A gel ointment suitable for application to wounds for the prevention of contracture is prepared according to the following formulation :- Carboxymethylcellulose 2.4% Hydroxyethylcellulose 0.3% Sodium chloride 0.24% Propylene glycol 20.2% Gly-Pro-Ala-Gly 0. 01% Water balance The sterile pharmaceutical gel was formulated under aseptic conditions.

The above embodiments have been described by way of example only. Many other embodiments falling within the scope of the accompanying claims will be apparent to the skilled reader.