Higher numbers of autologous fibroblasts in an artificial dermal substitute improve tissue regeneration and modulate scar tissue formation

Cultured skin substitutes are increasingly important for the treatment of burns and chronic wounds. The role of fibroblast numbers present in a living-skin equivalent is at present unknown. The quality of dermal tissue regeneration was therefore investigated in relation to the number of autologous fibroblasts seeded in dermal substitutes, transplanted instantaneously or precultured for 10 days in the substitute. A full-thickness porcine mound model was used to compare acellular dermal substitutes (ADS) with dermal substitutes seeded with fibroblasts at two densities, 1 x 10(5) (0-DS10) and 5 x 10(5) cells/cm(2) (0-DS50), and with dermal substitutes seeded 10 days before operation at the same densities (10-DS10 and 10-DS50) (n=7 for each group, five pigs). After transplantation of the dermal substitutes, split-skin mesh grafts were applied on top. Wound healing was evaluated blind for 6 weeks. Cosmetic appearance was evaluated and wound contraction mas measured by planimetry. The wound biopsies taken after 3 weeks were stained for myofibroblasts (alpha-smooth muscle actin), and after 6 weeks for scar tissue formation (collagen bundles organized in parallel and the absence of elastin staining). Collagen maturation was investigated with polarized light. For mound cosmetic parameters, the 10-DS50 and 0-DS50 treatments scored significantly better than the ADS treatment, as did the 10-DS50 treatment for wound contraction (p<0.05, paired t-test). Three weeks after wounding, the area with myofibroblasts in the granulation tissue, determined by image analysis, was significantly smaller for 0-DS50, 10-DS10, and 10-DS50 than for the ADS treatment (p<0.04, paired t-test). After 6 weeks, the,wounds treated with 0-DS50, 0-DS10, and 10-DS50 had significantly less scar tissue and significantly more mature collagen bundles in the regenerated dermis. This improvement of wound healing was correlated with the higher numbers of fibroblasts present in the dermal substitute at the moment of transplantation. In conclusion, dermal regeneration of experimental full-skin defects was significantly improved by treatment with dermal substitutes containing high numbers of (precultured) autologous fibroblasts. Copyright (C) 2000 John Wiley & Sons, Ltd.