The Experimental Study Of The Biocompatibility And Slow Release Of PEG-PELG Hydrogel Carrying NGF

OBJECTIVE:PEG-PELG hydrogel is a new kind of slow release carrier of drug. The aim of this study is to investigate the biocompatibility and slow release of the NGF carried by PEG-PELG hydrogel and to provide a basis for further research and clinical use. MATERIALS AND METHODS:(1) C57 mice was used as experimental animal. PEG-PELG hydrogel was injected subcutaneously into the C57 mice.Its degradation at different times was observed to investigate its biocompatibility and degradation behavior in vivo.(2)We observed the slow release of PEG-PELG hydrogel carrying NGF in mock physiological conditions to investigate its release behavior.(3)To test the biological activity, the supernatant of NGF carried by hydrogel in 12-well culture plate was collected at 1,4,7,14 days and added in the culture of PC12 cells. The differentiation of PC12 cells was observed.(4)The ERK and Phospho-ERK of the PC12 cells dealed with NGF in last procedure was assayed to assess the biological activity of the released NGF. RESULTS:(1)After injection to the C57 rats subcutaneously, PEG-PELG hydrogel has degraded completely in 21 days, no obvious inflammatory adhension was observed with adjacent tissues.(2)The concentration of NGF released from 200ng/m L NGF carried with PEG-PELG hydrogel was determined by sandwich ELISA. The concentration of released NGF at the first day was about 18ng/m L and became lower in the following days. It was about 10ng/m L at the 7th day and 8ng/m L at the 14 th day.(3)The result of biological activity showed that it could still induce differentiation of PC12 cells with the 14 th day’s release culture.(4)The new form of NGF can slowly release active NGF which could promote the phosphorylation of the ERK in PC12 cells. CONLUSION:(1) The new form of NGF carried by PEG-PELG hydrogel has fine biocompatibility.(2) The new form of NGF carried by PEG-PELG hydrogel has the ability to release NGF slowly and keep it’s biological activity.(3) The new form of NGF could keep the biological activity of NGF for long.