Enhancement of ischemic wound healing by inducement of local angiogenesis

To determine if monocytes activated toward an angiogenic phenotype can be used to improve ischemic tissue healing in a rat skin flap model.

Prospective experimental study on Wistar rats.

A caudally based 9 x 3 cm dorsal skin/panniculus carnosus flap was raised in 15 rats. The animals were divided into three groups: the monocyte group (N = 5) received subcutaneous topical application of 0.1-0.2 cc of i-Monogrid, a collagen gel containing M2 angiogenic monocytes; control group 1 (N = 5) received application of cell-free collagen; and control group 2 (N = 5) received no treatment. Skin flaps were stapled in place and observed for wound ischemia and necrosis of the skin flap. One week postoperatively, skin and underlying muscle were harvested for histologic analyses.

No macroscopic differences in wound healing or microscopic differences in skin viability were observed. However, the monocyte group showed significantly greater vascular improvement than C1 (P = .047, chi = 3.96), and a trend toward greater vascular improvement than C2 (P = .103, chi = 2.67).

Delivery of activated pro-angiogenic monocytes to an ischemic skin flap tended to improve histologic evidence of vascularity without corresponding microscopic or gross evidence of improved flap survival. These results are encouraging regarding the use of monocytes as a potential method of improving vascularization of ischemic tissue.