Impaired wound healing is one of the most common complications associated with diabetes. Adiponectin is an abundant circulating adipocyte-derived cytokine that has beneficial effects on disorders accompanying diabetes. Herein we report that adiponectin has a regulatory effect on the growth and differentiation of HaCaT human keratinocyte cells. Furthermore, adiponectin regulated the expression of TGF beta isoforms in keratinocytes in a dose-dependent manner, which implies that adiponectin modulates other types of cells related to wound repair via secretion of growth factors from keratinocytes. Moreover, TUNEL assay results revealed that adiponectin enhances apoptosis of keratmocytes. Taken together, the present results indicate that adiponectin has suppressive effects on the formation of hyperkeratosis commonly seen in patients with diabetic foot and its application may be beneficial for developing treatment for that disorder. (C) 2008 Elsevier Inc. All rights reserved.