Effects of heat injured keratinocytes supernatant on proliferation and collagen I mRNA expression of dermal fibroblasts

Abstract

Objective To observe the effects of heat injured keratinocyte (KC) supematant on proliferation activity and collagen mRNA expression of the normal fibroblast (Fb).Methods A model of heat injured KC in vitro was reproduced,the supernatants of heat injured KC were collected and used as conditioned medium,and DMEM was used as control medium.Normal Fb were treated with different concentrations of conditioned medium.After treatment for 24 h,the proliferation activity,cell cycle and collagen Ⅰ mRNA levels in treated Fb were measured by using methylthiazol tetrazolium ( MTT),flow cytometry (FCM) and real-time polymerase chain reaction (PCR) techniques.Results As compared with the control group,the absorbance (A) values of MTT in treated groups were significantly increased (t = 4.01,11.42,11.41 ;P ＜0.05),except in 10% group (t = 1.34,P ＞0.05).As compared with normal supernatant treated group (0.159 ± 0.002,0.180 ± 0.005,0.181 ± 0.006),the A values in 50% and 70% conditioned medium group (0.195 ± 0.006,0.202 ± 0.008 ) were significantly increased ( t = 2.03,1.94;P ＜0.05).The 50% conditioned medium increased the percentage of G1 to S and S to G2 phase transit.As compared with control group,the number of cells in S and G2/M phase was increased significantly (t =5.87,11.3;P＜0.05 ) and that in G0/G1 phase decreased significantly ( t = 4.86;P＜0.05 ).Real-time PCR revealed that the collagen Ⅰ mRNA level in 50% conditioned medium group was significantly up-regulated (t= 1.72;P＜0.05 ) as compared with control group.Conclusion Heat injured KC supernatant may promote the proliferation of dermal Fb,and up-regulate the mRNA expression of collagen. Key words: Heat injury; Keratinocyte; Cytoproliferation; Collagen