Skin renewal and repair requires a healthy immune system, including a pool of normal epidermal skin stem cells and bone marrow stem cells. Impaired normal skin and/or bone marrow stem cells can delay wound healing. Bone marrow contains mesenchymal stem cells (MSCs), which have multipotency and regenerative activity. To evaluate the efficacy and safety of MSC transplantation for wound closure and regeneration, MSCs were harvested from 10 beagles and cultured in vitro. Full-thickness skin wounds were created using disposable dermal biopsy punches; 24 hours later, multiple solutions of different concentrations of MSCs or saline were transplanted via intradermal injection into the wounds.

Wound closure rate, amount of collagen production (assessed by routine histological examination of tissues), and degree of cellular proliferation and angiogenesis (assessed by immunocytochemistry) were evaluated. Compared with control dogs, MSC-treated wounds showed faster closure; increased cell proliferation, collagen synthesis, and angiogenesis; and decreased production of proinflammatory cytokines and other wound healing factors. The dogs appeared tolerant of the treatment, and wounds healed without infection and with normal scarring. Topical application of MSCs may help large or nonhealing wounds.

Wound healing relies on angiogenesis, collagen deposition, and epithelialization, all of which improved with this experimental treatment. Although the requirement for immunomodulation with systemic treatment using allogeneic MSCs is still unclear, local application may negate the concern for patient reaction and adverse effects of immunosuppressive treatment. Banks of allogeneic MSCs allow for more cost-effective and timely treatment, compared with harvesting and culturing autologous cells. Expedited wound healing may translate to fewer hospital visits, less patient discomfort, and decreased client cost.

Before its general use is recommended, this therapy should be compared with other, more conventional methods of open wound management, but results appear promising. Locally applied allogeneic MSCs may also prove to be useful for open wound management.—Brian J. Sutherland, DVM, & Jason Bleedorn, DVM, DACVS

The effects of topical mesenchymal stem cell transplantation in canine experimental cutaneous wounds. Kim JW, Lee JH, Lyoo YS, et al. VET DERMATOL 24:242-e53, 2013.