173 Autologous Bone Marrow-Derived Cells for Accelerating the Healing of Human Chronic Wounds

Abstract

We have previously shown that resident fibroblasts from human chronic wounds are phenotypically abnormal, displaying an impaired response to TGF-beta 1, decreased TGF-beta Type II receptor expression, and decreased phosphorylation of Smad2, Smad3, and p42/44 MAPK. We now report that these human cells delay healing by approximately 30% when implanted in mouse incisional wounds and in a dorsal flap model. These new findings point to the need for the transplantation of new healthy cells in human chronic wounds. Bioengineered living skin constructs can deliver new cells to chronic wounds, at least for a limited period of time. However, most available bioengineered skin constructs consist of already differentiated allogeneic cells, which do not allow for the possibility of engraftment and reconstitution of wound structures. Recently, in a preliminary report, we have shown that autologous bone marrow-derived cells can dramatically enhance the healing of recalcitrant chronic wounds when all other treatments have failed. Our present efforts are now focused on characterizing the bone marrow cells involved in this stimulation of wound healing and in developing better ways for their topical delivery to the wound. Here we present evidence that a fibrin construct may be an ideal way of applying bone marrow-derived cells to human chronic wounds. Autologous bone marrow cells are allowed to grow in culture under conditions favoring the survival and proliferation of mesenchymal stem cells (MSC), as shown by surface markers and functional studies. This usually requires two weeks after bone marrow harvesting. The cellular component is then placed in a fibrinogen solution which, when simultaneously combined with thrombin through a CO2 driven flow, delivers a fine cell-containing fibrin polymer film to the wound. In vitro and in vivo experiments, both in mouse models and in human wounds, show the feasibility of this approach.