BACKGROUND The formation of wrinkles is associated with degeneration of the collagen matrix. For regeneration of the matrix, fibroblasts need to be stimulated in producing new collagen. OBJECTIVE In this study, the effect of short-pulsed heat shocks on gene expression of procollagen type I, procollagen type III, heat shock protein (hsp)27, hsp47 and hsp70 and on the expression of remodeling markers, procollagen type I carboxy-terminal peptide (P1P) and carboxy-terminal telopeptide of type I (ICTP), of human dermal fibroblasts in vitro, is investigated. METHODS Temperatures of 45 degrees C and 60 degrees C were used for the heat shocks. The proliferation rates, viability and metabolic activity were measured directly after the pulsed heat shocks and quantitative PCR was performed at five different time points after the heat shocks. Enzyme Immuno Assays were performed to determine the concentrations of P1P and ICTP. RESULTS A decreased proliferation rate of the 60 degrees C heat shocked cells was shown, whereas the viability and metabolic activity did not differ. Furthermore, gene expressions were upregulated in both 45 degrees C and 60 degrees C heat-shocked cells. However, remodeling marker analyses showed a larger amount of collagen produced by 60 degrees C heat-shocked cells. CONCLUSIONS It can be concluded that these findings, together with upregulation in gene expression, show that it is possible to stimulate the cells to produce more collagen with short-pulsed heat shocks.