Differential expression of wound fibrotic factors between facial and trunk dermal fibroblasts

Dermal fibroblast from superficial layers of pig skin exhibits more proliferative capacity than that from deep layers

OBJECTIVE

To further examine the feasibility of using pigs as an animal model for the study of dermal fibroblast heterogeneity and to explore the proliferative capacity of dermal fibroblasts from different layers of pig skin in vitro and in vivo.

MATERIAL AND METHODS

Cultured superficial and deep dermal fibroblasts were subjected to cell growth assay, cell cycle analysis, immunocytochemical staining and western blotting for proliferating cell nuclear antigens. Moreover, skin samples autografted with superficial/deep dermal fibroblasts were subjected to immunohistochemical staining and western blotting for proliferating cell nuclear antigen.

RESULTS

The cell growth assay showed that the growth curve of the superficial dermal fibroblast was progressively higher than that of the deep layer. The cell cycle analysis showed that the (G2+S) percentage of the superficial dermal fibroblasts was significantly higher than that of the deep layer fibroblasts. The immunocytochemical staining and western blotting showed that the expression of proliferating cell nuclear antigen in the cultured superficial dermal fibroblast was significantly higher than that of the deep layer cells. The immunohistochemical staining showed that the positive rate of proliferating cell nuclear antigen in the skin samples autografted with the superficial dermal fibroblast was significantly higher than that of the deep layer.

CONCLUSIONS

This study has demonstrated that similar to human dermal fibroblasts, dermal fibroblasts from different layers of pig skin exhibit distinct proliferative capacity, which increases the feasibility of using pigs as an animal model for future studies on the heterogeneity of dermal fibroblasts.

Development of de novo epithelialization method for treatment of cutaneous ulcers

Cutaneous ulcers are a common cause of morbidity. We have developed a de novo epithelialization method for treating cutaneous ulcers by means of reprogramming wound-resident mesenchymal cells in vivo into cells able to form a stratified epithelium: induced stratified epithelial progenitors (iSEPs). Administration of 4 transcription factors (DNP63A, GRHL2, TFAP2A, and cMYC) expressed via adeno-associated viral vectors enabled generation of epithelial cells and tissues, thereby acheiving de novo epithelialization from the surfaces of cutaneous ulcers in a mouse model. Generated epithelia, having barrier functions equivalent to the original epidermis, were maintained for more than 6 months. Our findings constitute a proof of concept for future development towards innovative therapies for cutaneous ulcers via de novo epithelialization.

Deep dermal fibroblast profibrotic characteristics are enhanced by bone marrow-derived mesenchymal stem cells

Hypertrophic scars are a significant fibroproliferative disorder complicating deep injuries to the skin. We hypothesize that activated deep dermal fibroblasts are subject to regulation by bone marrow-derived mesenchymal stem cells (BM-MSCs), which leads to the development of excessive fibrosis following deep dermal injury. We found that the expression of fibrotic factors was higher in deep burn wounds compared with superficial burn wounds collected from burn patients with varying depth of skin injury. We characterized deep and superficial dermal fibroblasts, which were cultured from the deep and superficial dermal layers of normal uninjured skin obtained from abdominoplasty patients, and examined the paracrine effects of BM-MSCs on the fibrotic activities of the cells. In vitro, deep dermal fibroblasts were found higher in the messenger RNA (mRNA) levels of type 1 collagen, alpha smooth muscle actin, transforming growth factor beta, stromal cell-derived factor 1, and tissue inhibitor of metalloproteinase 1, an inhibitor of collagenase (matrix metalloproteinase 1). As well, deep dermal fibroblasts had low matrix metalloproteinase 1 mRNA, produced more collagen, and contracted collagen lattices significantly greater than superficial fibroblasts. By co-culturing layered fibroblasts with BM-MSCs in a transwell insert system, BM-MSCs enhanced the fibrotic behavior of deep dermal fibroblasts, which suggests a possible involvement of BM-MSCs in the pathogenesis of hypertrophic scarring.