We examined the effects of the transparent fibroin film (silk film) on full-thickness skin wounds. Full-thickness dermatotomies (15 mm x 9 mm) were prepared on the dorsal wall of CRJ:CD-1 nu/nu (ICR nu/nu) mice. The area of the wounds dressed with silk film was reduced to 10% of that made by the dermatotomy 14 days after the dermatotomy and were covered with regenerated epidermis 21 days after the dermatotomy. In contrast, less recovery and epidermal regeneration were found 14 days after dermatotomy in the wounds dressed with a conventional hydrocolloid dressing (Duro Active). Furthermore, only partial incomplete epidemal growth was obtained 21 days after dermatotomy. Most importantly, the healing time of wounds dressed with silk film was 7 days shorter than those dressed with DuoActive dressing. The silk film showed an almost similar or slightly better promotive effect as the lyophilized porcine dermis (Alloask D), which is used as a dressing for burns, ulcers, and decubitis. Histologic findings revealed that there was greater collagen regeneration and less inflammation and neutrophil-lymphocyte infiltration of the wounds dressed with silk film than with DuoActive dressing. It is clear that regeneration of the epidermis and dermis of the wound beds covered with silk film was faster than with DuoActive dressing. Finally, silk film is easily obtainable, sterilizable, and transparent, and it allows easy observation of tissue recovery. Therefore, silk film offers advantages over other dressings and may be clinically useful for wound treatment.

A strategy to achieve regular and long lasting organ and tissue allografts without using immunosuppressants and͞or irradiation has been established for mice. One hundred percent of skin allografts can be induced to survive >350 days after transplantation if spleen cells from the same donors are first injected into the portal vein of the recipients. The mechanisms underlying this long-term tolerance induction can be described as follows: (i) donor T cells from the spleen of the donor facilitate the acceptance of the allogeneic engraftment, (ii) donor-specific anergy is induced in the cytotoxic T-lymphocytes of the recipients, (iii) T helper type 2 cells become the dominant T cells in the recipients that are accepting the skin transplants, and (iv) a lasting chimerism (microchimerism) is established in these recipients. This strategy, perhaps with minor modifications, might permit one also to overcome major barriers to organ allografting in humans. If this were the case, it could represent production of long lasting immunologic tolerance without need for irradiation or cytotoxic chemo-preparative regimen and as such could greatly facilitate allotransplantation free of episodes of chronic or acute rejection or toxic and damaging preparatory regimens.

No abstract

Abstract. We examined the effects of the transparent fibroin film (silk film) on full‐thickness skin wounds. Full‐thickness dermatotomies (15 mm × 9 mm) were prepared on the dorsal wall of CRJ:CD‐1 nu/nu (ICR nu/nu) mice. The area of the wounds dressed with silk film was reduced to 10% of that made by the dermatotomy 14 days after the dermatotomy and were covered with regenerated epidermis 21 days after the dermatotomy. In contrast, less recovery and epidermal regeneration were found 14 days after dermatotomy in the wounds dressed with a conventional hydrocolloid dressing (Duro Active). Furthermore, only partial incomplete epidemal growth was obtained 21 days after dermatotomy. Most importantly, the healing time of wounds dressed with silk film was 7 days shorter than those dressed with DuoActive dressing. The silk film showed an almost similar or slightly better promotive effect as the lyophilized porcine dermis (Alloask D), which is used as a dressing for burns, ulcers, and decubitis. Histologic findings revealed that there was greater collagen regeneration and less inflammation and neutrophil‐lymphocyte infiltration of the wounds dressed with silk film than with DuoActive dressing. It is clear that regeneration of the epidermis and dermis of the wound beds covered with silk film was faster than with DuoActive dressing. Finally, silk film is easily obtainable, sterilizable, and transparent, and it allows easy observation of tissue recovery. Therefore, silk film offers advantages over other dressings and may be clinically useful for wound treatment.