BACKGROUND:The tensile and stress-relaxation mechanical properties of sciatic nerve injury after repaired with autologous nerve and poly(lactic acid-glycolic acid) (PLGA) scaffold are rarely reported. OBJECTIVE:To analyze the tensile and stress relaxation characteristics of sciatic nerve injury after the transplantation of autologous nerve and PLGA scaffold. METHODS:Sixty sciatic nerves were extracted from the fresh cadavers dead within 24 hours, processed into 35 mm samples, and were then randomly divided into three groups. The nerve samples in control group received no intervention;the nerves in artificial and autologous groups were modeled into 20 mm defects, followed by repaired with PLGA scaffold and autologous nerve, respectively. Afterwards, the tension and stress-relaxation tests were performed in each group. RESULTS AND CONCLUSION:The stress in each group descended fast at the first 600 seconds, then descended slowly and was closed to the horizontal level until 7200 seconds, and the stress-relaxation curves in each group were in logarithmic decrease. The order of the elastic limit load, elastic limit stress, maximum load, maximum stress, elastic limit strain and maximum strain during tension was as follows:control group>artificial group>autologous group (P<0.05). Our results indicate that the PLGA scaffold holds good tension and stress-relaxation properties, which meets the mechanical requirements of the biomaterials used for sciatic nerve repair.

BACKGROUND:In recent years, great progress has been achieved in the mechanical and viscoelastic properties of arterial blood vessels of normal human corpses and animals. OBJECTIVE: To quantitatively analyze the tensile mechanical properties of thoracic aorta in normaly fed spontaneously hypertensive rats and salt-loaded spontaneously hypertensive rats. METHODS: Twenty spontaneously hypertensive rats were obtained and randomly divided into experimental and control groups (n=10/group). Rats in the experimental group were subjected to continuous salt loading intervention for 16 weeks. Rats in the control group were fed with normal diet and ordinary tap water. At the 16th week, 10 specimens of thoracic aorta of rats from these two groups were harvested to conduct stress relaxation experiments.RESULTS AND CONCLUSION: The decrease in stress at 7 200 seconds and the decrease in normalized stress relaxation function value at 7 200 seconds of thoracic aortic specimens of rats in experimental group were both lower than those in the control group (P< 0.05). These results confirm that the stress relaxation properties of thoracic aorta of normaly fed and salt-loaded spontaneously hypertensive rats change, wherein the changes in salt-loaded spontaneously hypertensive rats are more obvious.