ABSTRACT
BACKGROUND: Numerous experiments and clinical practice show that human hair keratin artificial tendon induces the organism to form autogenous tendon. The process of autogenous tendon formation mainly involves the synthesis, secretion and package of collagen subtype I.OBJECTIVE: To explore the role of collagen subtype I mRNA expression in autologous tendon formation after human hair keratin artificial tendon implantation.DESIGN: A completely randomized controlled experiment based on the experimental animals.SETTING: Department of Histology and Embryology and Department of Biochemistry and Molecular Biology of Southern Medical University.MATERIALS: The experiment was conducted in the Experimental Animal Center of the First Military Medical University of Chinese PLA from May 2003 to September 2004. Totally 33 New Zealand rabbits of either gender,weighing 2.0 to 2. 5 kg, were provided by the center. The animals were randomly divided into experiment 3, 6, 9, 12, 16 and 20 weeks groups, negative control 9 and 20 weeks groups and normal control group. Among them,experiment 3 and 6 weeks group and normal control group had 3 rabbits in each and the other groups had 4 rabbits. Human hair keratin artificial tendons were normal human hair treated by a series of biochemical methods and were supplied by the Department of Biochemistry & Molecular Biology of the university. The human hair keratin artificial tendons were divided into three groups with different degradation rates, namely, fast(F), medium(B) and slow(Z). The tendons were made up of the fast, medium and slow degradation groups mixed at the ratio of 4: 3: 3.off by 1.0- 2.0 cm, human hair keratin artificial tendon was grafted by end-to-end anastomosis with both ends of the broken tendon before sewing control group, no artificial tendon was implanted although the animals ungroup was normal rabbits' tendon. Sampling was carried out at 3, 6, 9, 12, 16and 20 weeks after human hair keratin artificial tendon implantation in experiment groups, and at 9 and 20 weeks after operation in negative control group, respectively. The expression of collagen subtype I mRNA was detected at weeks 3, 6, 9, 12, 16 and 20 after grafting using reverse transcription polymerase chain reaction technique.MAIN OUTCOME MEASURES: The ratio of collagen subtype I mRNA to Glyceraldehyde-3-phosphate dehydrogenase(GADPH) mRNA in normal tendon and autogenous tendon induced by human hair keratin artificial tendon at all time points was calculated, and significance test between all these paired groups were performed.collagen subtype I mRNA/GADPH mRNA expression was 0.96 ±0.02 in expression of collagen subtype I mRNA/GADPH mRNA in autogenous tendon induced by human hair keratin artificial tendon in experiment group appeared at week 3, increased rapidly at week 3 to 6, peaked at week 6, and remained stable at week 9 to 20. The expression at week 6 was significantly higher in experiment group than in normal control group( F = 6. 254, P ＜ 0.05); the expression at other weeks was also significantly higher in experiment group than in normal control group( F= 1. 258 - 1. 987, P ＞ 0.05).CONCLUSION: The activation, proliferation and secretion of collagen protein as well as the synthesis of collagen subtype I by tenocytes may be responsible for autologous tendon formation after human hair keratin artificial tendon implantation.