1.Genipin crosslinked preparation of new peripheral nerve tissue engineered scaffolds and comparison of their biological characteristics
Mo LI ; Bangyao WU ; Xueyu HU ; Jinghui HUANG ; Yonggnang ZHANG ; Zhuojing LUO
Chinese Journal of Trauma 2010;26(2):165-171
Objective To compare biological properties of ehitosan composite artificial neural type Ⅰ collagen scaffold material cross-linked with ultraviolet rays (UV), genipin (GP) and glutaraldehyde (GTA) in aspects of uhrastrueture, porosity, swelling rate, degradation rate, crosslinking degree and cytotoxicity. Methods (1) According to different cross-linking methods, biomaterials were divided into three groups, ie, UV group, GP group and GTA group. (2)The mierostrueture of three groups was observed under scanning electron microscope (SEM) to measure pore size, porosity rate and pore-size distribution. (3)Swelling rate and in vitro degradation rate:the biomaterials were weighed (W_0) after crosslinking and then immersed in culture medium containing 10 ml aseptic phosphate buffer solution (PBS). The samples were drawn from the culture medium after 24 hours, wiped with filter paper to remove excess liquid and weighed (W_1). Swelling rate(%) = W_1-W_0/W_0×100%. The remaining sampies from each group were weighed (W_2) at 4, 8, 12 weeks with the same procedure. Degradation rate (%) = W_1-W_2/W_1×100%. (4)Determination of cross-linking index: 10 samples were prepared from each group, five samples from which were reacted with trinitro-benzen-sulfonic acid(TNBS)and sodium bicarbonate and then were hydrolyzed with hydrochloric acid. The absorbance of the diluted solution was measured at 346 nm. The other five samples were prepared by the same procedure, except for hydrochloric acid was added before addition of TNBS, when the absorbance was measured as control (A_(control)). The absorbance after crosslinking:A_(after)=ATNBS-A_(control). Another 10 samples without any crosslinking were detected with the same procedure to measure the absorbance before crosslinking (A_(before)). Crosslinkiag index = (A_(before)-A_(after))/A_(before)×100%. (5) Determination of cytotoxicity : two international standard experimental methods were adopted in the study according to experimental principle of GB/T 16886-ISO 10993 on medical apparatus. L929 fibroblasts of mouse were used for in vitro experimental study of cytotoxicity of modified scaffold. Results The biomaterials without any cross-linking were circular cylinder, with parallel arranged microscopic channel and uniform pore size of 30-120 μm. The pore size of UV group remained basically unchanged, while the pore size in GP group and GTA group was smaller than that in UV group. (2) The porosity rate in GP group and GTA group was higher than that in UV group, but there was no statistical difference between GP group and GTA group. The swelling rate of GP group was higher than that GTA group, which was higher than UV group. (3)The crosslinking index of GP group and GTA group were 55.3% and 82.5%. (4) No statistical difference was found in regard of in vitro degradation rate after GP group and GTA group were put in PBS for4, 8 and 12 weeks, respectively. But in vitro degradation rate in UV group was significantly higher than that in GP group and GTA group. (5) Cell culture in GTA group presented partial necrosis, while cells cultured in GP group and UV group grew well. Conclusion Collagen/chitosan scaffolds cross-linked with GP have sound biostability and good biocompatibility and hence are potential alternatives for nerve tissue engineering.