Acceleration of cutaneous wound healing by transient p53 inhibition

The increase of cell proliferation during early wound healing is thought to be regulated by a decrease of apoptosis. In contrast, the reduction of cellularity during final wound maturation may be controlled by an increase of apoptotic cell death. Herein we studied whether p53 is involved in wound healing-associated apoptosis and whether transient inhibition of p53 is effective to improve the early healing process of cutaneous wounds. Using intravital microscopic and immunohistochemical techniques in hairless mice, we demonstrated that in vivo inhibition of p53 by pifithrin-alpha (PFT-alpha; 2.2 mg/kg ip) accelerates early epithelialization and neovascularization of cutaneous wounds by (i) promoting leukocyte recruitment, (ii) increasing cell proliferation, and (iii) reducing apoptotic cell death. We further show that final wound closure with down-regulation of cell proliferation is not inhibited by PFT-alpha treatment, indicating that transient blockade of p53 function does not affect the process of wound maturation. Western blot analysis revealed that PFT-alpha lowered nuclear but not cytoplasmic p53, implying that cytoplasmic retention of p53 mediates the antiapoptotic effects of PFT-alpha. Furthermore, PFT-alpha significantly increased expression of proliferating cell nuclear antigen protein in whole extracts of cutaneous tissue and caused a rise in proliferation of wild-type, but not mutant, p53-expressing keratinocytes. From our study we conclude that transient inhibition of p53 supports the early cell proliferation required for rapid tissue repair and that this may represent an attractive approach in the treatment of delayed wound healing.