Chronic wounds continue to be a major cause of morbidity for patients and an economic burden on the health care system. Novel therapeutic approaches to improved wound healing will need, however, to address cellular changes induced by a number of systemic comorbidities seen in chronic wound patients, such as diabetes, chronic renal failure, and arterial or venous insufficiency. These effects likely include impaired inflammatory cell migration, reduced growth factor production, and poor tissue remodeling. The multifunctional properties of bone marrow-derived mesenchymal stem cells (MSCs), including their ability to differentiate into various cell types and capacity to secrete factors important in accelerating healing of cutaneous wounds, have made MSCs a promising agent for tissue repair and regeneration. In this study we have used an in vitro scratch assay procedure incorporating labeled MSCs and fibroblasts derived from normal donors and chronic wound patients in order to characterize the induction of mobilization when these cells are mixed. A modified Boyden chamber assay was also used to examine the effect of soluble factors on fibroblast migration. These studies suggest that MSCs play a role in skin wound closure by affecting dermal fibroblast migration in a dose-dependent manner. Deficiencies were noted, however, in chronic wound patient fibroblasts and MSCs as compared with those derived from normal donors. These findings provide a foundation to develop therapies targeted specifically to the use of bone marrow-derived MSCs in wound healing and may provide insight into why some wounds do not heal.

Bone marrow-derived cells have long been regarded to play a crucial role in the homeostasis of skin. We have previously described the clinical benefit of directly applying autologous bone marrow aspirate and cultured bone marrow cells to recalcitrant chronic skin wounds. The initial response to treatment appears to be vascular in nature with the formation of new blood vessels. The difficulty in consistently growing adequate numbers of cells for delivery to patients was, however, a limiting factor. Here, in a subsequent protocol, we describe an improved bone marrow culture system yielding a reliable growth of bone marrow cells and leading to a greater clinical response. Cells expressing markers of endothelial progenitors including CD133, CD146, and particularly CD14 are enhanced in these cultures. CD14-isolated cells produced colonies in endothelial cell assays and sprouting in matrigel assays. Angiogenic cytokines, including angiogenin, epithelial neutrophil-activating protein-78, growth-regulated oncogene, growth-regulated oncogene-alpha, Interleukin-8, CXC16, and monocyte chemoattractant protein-1, were found to be elevated in these cultures. Administration of improved culture cells to patients with chronic wounds present for >1 year lead to an enhanced clinical response.