Abstract： Objective To investigate the most effective method to promote human embryonic lung fibroblast proliferation,we established several novel local fibrin-gel delivery systems,which could continuously release multiple growth factors in vitro.Methods Multiple growth factors,including platelet-derived growth factor (PDGF),vascular endothelial growth factor (VEGF),transforming growth factor (TGF) and epidermal growth factor (EGF) were added to fibrinogen solutions.These multiple growth-factor-containing fibrinogen solutions were converted to fibrin gel using thrombin to establish a delivery system.The kinetics and dissolution curves of the different fibrin-gel delivery systems were determined by daily measurement of the dissolved collagen volume.Human embryonic lung fibroblasts were randomly divided into 2 groups:the growth-factors (group A) and the non-growth-factors groups (group B).Based on the fibringel shape,groups A and B were both randomly divided into 4 sub-groups ; the fully-covered fibrin-gel,island fibrin-gel,scattered punctiform fibrin-gel and medium without fibrin-gel control groups.Cell proliferation was determined by cell counting and cell viability using the methyl thiazolyl tetrazolium (MTT) assay.Cell proliferation rate was measured by MTT.Results (1) The peak of growth factors releasing from gel of island group was 8.2 ± 0.8 days,while that of scattered punctiform group was 8.0 ± 1.0 days,and that of the fully-covered fibrin-gel group was 9.8 ± 0.4 days.The trend of growth factor releasing was significantly different among groups(F =31.054,P ＜ 0.05).There was no statistical difference in the release kinetics between the island group and the scattered punctiform group (t =1.000,P ＞ 0.05).The peak of growth factors releasing from gel of the fully-covered fibrin-gel group was later than that of the island groups and the scattered punctiform fibrin-gel group (t =6.820,P ＜ 0.01).(2) The cell proliferation rate of island gel containing growth factors subgroup(107.6 ± 1.1) ％ grew more rapidly than island gel without growth factors subgroup (73.2 ± 2.2)％ (F =375.29,P ＜ 0.01).The cell proliferation rate of the scattered punctiform gel containing growth factors subgroup (141.2 ± 1.8) ％ grew more rapidly than the scattered punctiform gel without growth factors subgroup(106.0 ± 2.8) ％ (F =2 274.48,P ＜ 0.01).(3) The trend of growth factor releasing of the scattered punctiform group was significantly faster than that of the island group (F =12.392,P ＜0.01).Conclusion (1) Multiple growth factors,including PDGF,TGF,VEGF and EGF,stimulate human embryonic lung fibroblast growth and proliferation.(2) The enhancement effect of the scattered punctiform fibrin-gel multiple growth-factor-releasing system on cell growth and proliferation was greater compared with the island fibrin-gel multiple growth-factor-releasing system.