The healing of full-thickness skin defects requires extensive synthesis and remodeling of dermal and epidermal components. Fibroblasts play an important role in this process and are being incorporated in the latest generation of artificial dermal substitutes. We studied the fate of fibroblasts seeded in our artificial
elastin/
collagen dermal substitute and the influence of the seeded fibroblasts on cell migration and dermal substitute degradation after
transplantation to experimental full-thickness
wounds in pigs.
Wounds were treated with either dermal substitutes seeded with autologous fibroblasts or acellular substitutes. Seeded fibroblasts, labeled with a
PKH-26 fluorescent cell marker, were detected in the
wounds with fluorescence microscopy and quantitated with flow cytofluorometric analysis of single-cell
suspensions of
wound tissue. The cellular infiltrate was characterized for the presence of mesenchymal cells (
vimentin), monocytes/macrophages, and vascular cells. Dermal substitute degradation was quantitated by image analysis of
wound sections stained with Herovici's staining. In the
wounds treated with the seeded dermal substitute, fluorescent PKH-26-labeled cells were detectable up to 6 d and were positive for
vimentin but not for the macrophage antibody. After 5 d, flow cytofluorometry showed the presence of 3.1 (+/-0.9) x 10(6) (mean +/- SD, n = 7) PKH-26-positive cells in these
wounds, whereas initially only 1 x 10(6) fluorescent fibroblasts had been seeded. In total, the percentage of mesenchymal cells minus the macrophages was similar after 5 d between
wounds treated with the seeded and the acellular substitutes. In the
wounds treated with the seeded substitute, however, 19.5% of the mesenchymal cells were of seeded origin. Furthermore, the rate of substitute degradation in the seeded
wounds was significantly lower at 2-4 wk after wounding than in
wounds treated with the acellular substitute. Vascular in-growth and the number of infiltrated macrophages were not different. In conclusion, cultured dermal fibroblasts seeded in an artificial dermal substitute and transplanted onto full-thickness
wounds in pigs survived and proliferated. The observed effects of seeded fibroblasts on dermal regeneration appeared to be mediated by reducing subcutaneous fibroblastic cell migration and/or proliferation into the
wounds without impairing migration of monocytes/macrophages and endothelial cells. Moreover, the degradation of the implanted dermal substitute was retarded, indicating a protective activity of the seeded fibroblasts.