海藻酸-壳聚糖-磷酰胆碱微囊生物相容性的研究

目的探讨磷酰胆碱修饰的新型海藻酸-壳聚糖微囊包裹胰岛对微囊生物相容性的影响。方法应用静电微囊发生技术获得磷酰胆碱修饰的海藻酸-壳聚糖微囊；利用考马斯亮蓝法分别测定单纯壳聚糖和磷酰胆碱修饰的壳聚糖对牛血清白蛋白的吸附量；将海藻酸．壳聚糖-磷酰胆碱微囊（实验组）和海藻酸一壳聚糖微囊（对照组）分别植入小鼠腹腔，4周后回收微囊，HE染色评价囊周纤维化情况；采用葡萄糖刺激试验评价微囊胰岛和单纯胰岛的胰岛素释放功能。结果单位质量的壳聚糖及磷酰胆碱修饰物所吸附的蛋白质量分别为189．4μg/mg和90．5μg/mg（t=5．549，P〈0．05），差异有统计学意义；微囊植入腹腔后，实验组囊表面细胞反应较对照组轻微，未见明显的纤维化形成；实验组微囊包裹胰岛与单纯胰岛在低糖溶液中，胰岛素浓度分别是（3．298±1．680）μIU／ml和（4．299±1．159）μIU／ml（t=1．096，P〉0．05），而在高糖溶液中分别是（11．783±4．175）μIU／ml和（12．875±2．268）μIU／ml（t=0．514，P〉0．05），差异均无统计学意义。结论磷酰胆碱修饰可提高海藻酸一壳聚糖微囊的生物相容性，同时不影响微囊胰岛生物学功能，更适用于微囊胰岛移植治疗糖尿病。

Biocompatibility of phosphorylcholine modified alginate-chitosan microcapsules

Objective To explore whether the biocompatibility of phosphorylcholine （PC） modified algi- nate-chitosan microcapsules could be improved. Methods PC modified alginate-chitosan microcapsules were ob- tained by high-voltage electrostatic system. Bradford method was adopted to determine the adsorption amounts of bovine serum albumin by chitosan alone and PC modified chitosan. Alginate-chitosan-PC microcapsules （experi- mental group） and alginate-chitosan microcapsules （control group） were respectively implanted into the peritoneal cavity of mice and retrieved 4 weeks after transplantation. Fibrosis of the capsules was evaluated by HE staining. Glucose stimulated insulin secretion （GSIS） assay was used to assess the insulin secretion response of encapsulated and nonencapsulated rat islets. Results The adsorption amount of protein was 189.4 μg/mg and 90. 5 μg/mg respectively by chitosan alone and PC modified chitosan. The difference had statistical significance （ t = 5. 549, P 〈 0. 05 ）. In contrast to the control group, the cellular reaction on the surface of the modified microcapsules was weaker, with no obvious fibrosis found. The insulin secreted by encapsulated islets and nonencapsulated islets was （3. 298 ± 1. 680） μIU/ml VS （4. 299± 1. 159 ） μIU/ml （ t = 1. 096, P 〉 0. 05 ） in response to low-glucose stimulus and（ 11. 783± 4. 175 ） μIU/ml VS （ 12. 875 ± 2. 268 ） μIU/ml （ t = 0. 514, P 〉 0.05 ） in response to high-glucose stimulus. Conclusions PC can improve the biocompatibility of alginate-chitosan microcapsules, with no effect on the biological function of encapsulated islets. It may be more appropriate to use modified micro- capsules encapsulating islets for transplantation.