Smooth muscle cell expression of a constitutive active form of human Rac 1 accelerates cutaneous wound repair.

Background: Hyperoxia has been shown to improve wound healing; however, the mechanism for such therapeutic effects of oxygen remains hypothetical. Rac 1 regulates a wide variety of cellular activities, including cell proliferation and migration, and also is a key regulator for the activity of the nicotinamide dinucleotide phosphate oxidase the enzyme complex responsible for the production of a large fraction of cellular superoxide.

Methods: We generated transgenic mice that express either the cDNA of a constitutively active mutant of human Rac 1 (V12 mutant or Rac CA) or the dominant negative isoform (V12 and N17 mutant or Rac DN) in the blood vessels using mouse vascular smooth muscle promoter for alpha-actin. We placed 2 wounds of 6 mm in diameter at the middorsal region of each mouse and allowed about 3 weeks for the wounds to heal.

Results: The size of the wounds in Rac CA transgenic mice was reduced relative to wild type mice; healing of Rac DN mice was slower than wild type and Rac CA ( P < .05). Blood vessel formation appeared faster in Rac CA mice, a finding associated with enhanced expression of some angiogenic growth factors.

Conclusion: The current studies suggest that Rac 1 activation accelerates the wound healing process and is associated with more efficient angiogenesis at the wound site.