Bulletin Autumn‧Winter 1996

Hospital Authority) have been conducting research on the i mp r o v eme nt of s k in culturing and grafting techniques. Their project, 'The Making and Evaluation of a Human Skin Substitute’, received a grant of HK$264,000 f r om the University Grants Committee in 1992. Us i ng Co l l a g en as D e r m i s a n d F i b r i n as Adhe s i ve The researchers set out to find a suitable dermis substitute. About 95 per cent of the human dermis consists of collagen, a fibrous p r o t e in that exists a b u n d a n t ly i n the extracellular matrix, tendons and bones of animals. Since the biological structure of the ligaments of cattle is very similar to the human dermis, collagen is extracted from such ligaments as dermis substitute and processed into the form of membranes in the l a b o r a t o ry to p r o v i de f o u n d a t i on coverage for burn wounds. Then, in their search for an adhesive, the researchers test the effects of fibrin, an insoluble protein in the b l ood wh i ch can help clotting. The hypothesis is that wh en extracted from serum, fibrin can act as a natural tissue glue which helps cultured skin adhere to the w o u nd surface. N u d e m i ce w e r e u s ed i n t he experiments because they have immune deficiency and therefore cannot reject the c u l t u r ed h u m an skin. A t wo - s q u a r e- centimetre wo u nd was inflicted on the back of the mice w h i ch were under general anaesthetic, and four different substances or combination of substances were used to cover the wounds ： (1) cultured skin ； (2) cultured skin and collagen ； (3) cultured skin and fibrin ； (4) cultured skin, collagen, and fibrin. I n a successful skin transplant, b l ood vessels connect w i th the cultured skin in a short time, providing it w i th nutrients for growth. The sooner vascularization occurs, the greater the chances of recovery; while the longer the wait, the greater the chances of w o u nd infection and rejection of the cultured skin. In the experiments w i th nude mice, the first three grafting methods were shown to have produced good results, with similar success rates. Wh e n used alone w i t h cultured skin, collagen or fibrin serves as a biocompatible bridge between the skin and t he w o u n d b e d. T he c u l t u r ed s k i n proliferates to f o rm the stratum corneum wh i ch is a biological barrier to bacteria. A combination of collagen, fibrin and cultured skin, however, seems to impose too great a diffusion barrier for the cultured skin to become vascularized. According to the experiments, therefore, cultured cells are best grafted directly onto the wo u nd bed or in combination w i th either a thin layer of collagen or fibrin, but not both. Two initial conclusions were drawn from the results. The first is that it is possible to cover the wo u nd bed w i th collagen and cultured skin at the same time. Experiment has shown that this method is valid on nude Recovering from serious burn after skin-grafting treatment Chinese University Bulletin Autumn • Winter 1996 26