Dorthyann Isackson, Kevin J. Cook, Lawrence D. McGill, Kent N. Bachus
Epidermal downgrowth, commonly associated with long-term percutaneous implants, weakens the skin-implant seal and greatly increases the vulnerability of the site to infection. To improve the skin attachment and early tissue integration with porous metal percutaneous implants, we evaluated the effect of bone marrow-derived mesenchymal stem cells (BMMSCs) to provide wound healing cues and vascularization to the dermal and epidermal tissues in establishing a barrier with the implant. Two porous metal percutaneous implants, one treated with BMMSCs and one untreated, were placed subdermally on the dorsum of Lewis rats. Implants were evaluated at 0, 3, 7, 28, and 56 days after implantation. Histological analyses evaluated cellular infiltrates, vascularization, quantity and quality of tissue ingrowth, epidermal downgrowth, and fibrous encapsulation. The amount of collagen infiltrating the porous coating was significantly greater for the BMMSC-treated implants at 3 and 28 days post implantation compared to untreated implants. There was an early influx and resolution of cellular inflammatory infiltrates in the treated implants compared to the untreated, though not statistically significant. Vascularization increased over time in both treated and untreated implants, with no statistical significance. Epidermal downgrowth was minimally observed in all implants with or without the BMMSC treatment. Our results suggest that BMMSCs can influence an early and rapid resolution of acute and chronic inflammation in wound healing, and can stimulate early collagen deposition and granulation tissue associated with later stages of wound repair. These findings provide evidence that BMMSCs can stimulate a more rapid and improved barrier between the skin and porous metal percutaneous implant.