Treatment of wounds

This invention relates to the use of cyclic guanosine 3′, 5′-monophosphate type five (cGMP PDE5) inhibitors (hereinafter PDE5 inhibitors), including in particular the compound sildenafil, for the treatment of chronic wounds of a non-diabetic origin including in particular chronic venous ulcers, chronic decubitus (pressure sores) and arterial ulcers; and acute wounds.

Anti-human polyclonal antiserum was raised in rabbits and affinity purified against the LIP-1 &lsqb;MERAGPSFGQQR&rsqb; peptide n accordance with the method of Fawcett et al (Proc Natl Acod Sci USA 2000; 97:3702-3707), corresponding to amino acid residues 1-12 of human PDE5A1. LIP-1 is specific for PDE5 A1. 4 &mgr;m sections of formalin-fixed paraffin embedded tissue were cut and picked up on to APES (3-aminopropyltriethoxysilane) coated slides and dried at 60° C. for 1 hour. Sections were de-waxed and rehydrated followed by proteolytic antigen retrieval in 0.1% trypsin in 0.1% calcium chloride &lsqb;pH7-6&rsqb; at 37° C. for 8 minutes. Following a brief water wash, endogenous peroxidase activity was blocked by incubation in 9 ml H 2 O 2 made up to 100 ml with distilled water for 10 minutes. Sections were washed in tap water then transferred to PBS. Excess buffer was removed from the slide and test sections were incubated in LIP-1 antibody diluted 1:600 in PBS for 1 hour at room temperature. Negative controls were included by omission of the primary antibody. Positive control tissue used was human corpus cavernosum. Immunodetection was carried out using DAKO Rabbit Envision TM system with 3-amino-9-ethylcarbazole (3AEC) as a substrate chromogen (red/brown staining). FIG. 1 illustrates a section of reactive but non-inflamed skin at the edge of a skin wound. The positive staining of the smooth muscle cells within the media of the venules and negative fibroblasts indicates the expression of PDE5 in the healing wound. Hyperplastic but intact squamous epithelium 1 is negative. The underlying dermis contains mature scar tissue with small and large venules 2 . Note the positive dark staining of the smooth muscle cells within the media of the venules (Original mag. ×10). FIG. 2 is a paraffin section taken from the border between a healing ulcer of 14 days (left) and intact epithelium (right). Again, the positive staining of the smooth muscle cells within the media of the venules (right) and the spindle cells (myofibroblasts) within the base of the ulcer (left) indicates PDE5 expression. Hyperplastic but intact squamous epithelium (right) and necrotic inflammatory exudate 3 is negative. Note the positive dark staining of the smooth muscle cells within the media of the venules 4 and of spindle cells within the base of the ulcer 5 (original mag. ×20). FIG. 3 is a paraffin section taken from the healed ulcer base w her e fascicles of young scar tissue have replaced normal dermal structures. Positive staining of some of the spindle cells (myofibroblasts) ( 8 ) and of some vascular structures is again indicative of PDE 5 expression. (Original mag ×20). FIG. 4 is a higher power view of the paraffin section of skin of FIG. 3 . The section is taken from the healed ulcer base where fascicles of young scar tissue have replaced normal dermal structures. PDE 5 expression is illustrated by the positive staining of some of the spindle cells (myofibroblasts) ( 9 ) and of some of the microvessels which have thin media ( 10 ). (Original mag x40). FIG. 5 is a higher powered view of FIG. 4 and shows a section taken from the healed ulcer base of FIG. 4 where fascicles of young scar tissue have replaced normal dermal structures. There is positive staining of some of the spindle cells (myofibroblasts) ( 11 ) which are present in acellular collagen. The immunolocalisation in the cytoplasm of some of these spindle cells has a patchy distribution. Positive staining of the medial smooth muscle cells within a small arteriole ( 12 ) indicates PDE 5 expression. There is negative staining of the lining endothelial cells ( 13 ) indicating the absence of PDE 5. (Original mag. ×60). FIG. 6 is also a higher powered view of FIG. 4 showing a section from the healed ulcer base in an area of relatively young scar tissue. Again, positive staining of some of the spindle cells (myofibroblasts) ( 14 ) and medial smooth muscle cells within the small arteriole (centre) ( 15 ) is indicative of PDE 5. In some of these spindle cells the immunolocalisation has a patchy distribution. (Original mag. ×60). The following formulation examples are illustrative only and are not intended to limit the scope of the invention. Active ingredient means a cGMP PDE5 inhibitor. Formulation 1: A tablet is prepared using the following ingredients: Sildenafil citrate (50 mg) is blended with cellulose (microcrystalline), silicon dioxide, stearic acid (fumed) and the mixture is compressed to form tablets. Formulation 2: An intravenous formulation may be prepared by combining the active ingredient (100 mg) with isotonic saline (1000 ml).