Effects of natural product extracts on contraction and mechanical properties of fibroblast populated collagen gel

Fibroblast-populated collagen gel cultures have been used as a dermal model of wound contraction and granulation in the wound healing process and as a n in vitro model of dermal tissue. We evaluated the effects of various natu ral product extracts on collagen gel contraction-promoting activity and mec hanical properties (relaxation time) using this model, and observed that so me natural product extracts, such as Hibamata extract (from Fucus vesiculos us) promoted gel contraction and increased the relaxation time of the gels. In addition, we investigated the mechanism of the promotion of the gel cont raction, noting increased expression of integrin alpha 2 and beta 1 subunit molecules on the surface of the fibroblasts, suggesting that some extracts , such as Hibamata extract, promote gel contraction by increasing the expre ssion of integrin molecules on the fibroblasts surface. For other types of natural product extracts, other mechanisms of the gel contraction-promoting activity, which were independent of an increase of integrins, were suggest ed. Although the mechanisms of promotion of gel contraction by these extracts a re still unclear, it is at least clear that, more than one mechanism appear s to be present. Therefore, more effective drug regimens for improving derm al tissues and wound healing may be achieved by combining drugs which incre ase integrin molecules and drugs with other mechanisms of action.