Wound healing from dermal grafts containing CD34+ cells is comparable to split-thickness skin micrografts.

Background: Epidermal stem cells present in the skin appendages of the dermis might be crucial in wound healing. In this study we located these cells in the dermis and evaluated their contribution to full-thickness wound healing in a porcine model. Methods: Four sequentially deeper 0.35mm thick skin grafts were harvested from the same donor site going down to 1.4 mm in depth (Layers 1-4). The layers were minced to 0.8 x 0.8 x 0.35 mm micrografts and transplanted (1:2) onto full-thickness porcine wounds. Healing was monitored up to 28 days and biopsies were collected on days 6 and 10. Multiple wound healing parameters were used to assess the quality of healing. Results: Our results showed that wounds transplanted with Layer 2 (0.35-0.7 mm) and 3 (0.7-1.05 mm) micrografts demonstrated comparable re-epithelialization rate as split-thickness skin graft (Layer 1- 0.00-0.35 mm; STSG) at day 10. At day 28 dermal micrografts (Layers 2 and 3) showed comparable quality of healing to STSGs (Layer 1) in terms of wound contraction and scar elevation index. The amounts of epidermal stem cells (CD34+) and basal keratinocytes (KRT14) at each layer were quantified by immunohistochemistry. Conclusions: The analysis evidenced that Layers 2 and 3 contained the most CD34 positive cells and Layer 1 was the richest in KRT14 positive cells. The immunohistochemistry also indicated that by day 6 CD34 positive cells had differentiated to basal keratinocytes (KRT14), which migrated from the grafts and contributed to the re-epithelialization of the wound. (C)2017American Society of Plastic Surgeons

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