Lamb M, Storrs R, Li S, Liang O, Laugenour K, Dorian R, Chapman D, Ichii H, Imagawa D, Foster C, King S, Lakey J R T
Department of Surgery, University of California at Irvine, Orange, California 92697, USA.
Transplant Proc. 2011 Nov;43(9):3265-6. doi: 10.1016/j.transproceed.2011.10.028.
Islet encapsulation offers an immune system barrier for islet transplantation, and encapsulation within an alginate sheetlike structure offers the ability to be retrievable after transplanted. This study aims to show that human islets encapsulated into islet sheets remain functional and viable after 8 weeks in culture or when transplanted into the subcutaneous space of rats. Human islets were isolated from cadaveric organs. Dissociation and purification were done using enzymatic digestion and a continuous Ficoll-UWD gradient. Purified human islets were encapsulated in alginate sheets. Human Islet sheets were either kept in culture, at 37°C and 5% CO(2), or transplanted subcutaneously into Lewis rats. After 1, 2, 4, and 8 weeks, the human islet sheets were retrieved from the rats and assessed. The viability of the sheets was measured using fluorescein diacetate (FDA)/propidium iodide (PI), and function was measured through glucose-stimulated insulin release, in which the sheets were incubated for an hour in low-glucose concentration (2.8 mmol/L) and then high (28 mmol/L), then high (28 mmol/L) plus 3-isobutyl-1-methylxanthine (50 μm). Human islet sheets remained both viable, above 70%, and functional, with a stimulation index (insulin secretion in high glucose divided by insulin secretion in low glucose) above 1.5, over 8 weeks of culture or subcutaneous transplantation. Islet transplantation continues to make advances in the treatment of type 1 diabetes. These preliminary results suggest that encapsulated islets sheets can survive and maintain islet viability and function in vivo, within the subcutaneous region.
胰岛封装为胰岛移植提供了一道免疫系统屏障，而封装在藻酸盐片状结构中则具备移植后可回收的能力。本研究旨在表明，封装在胰岛片中的人胰岛在培养8周后或移植到大鼠皮下空间时仍保持功能和活力。人胰岛从尸体器官中分离出来。采用酶消化和连续的Ficoll-UWD梯度进行解离和纯化。将纯化的人胰岛封装在藻酸盐片中。人胰岛片要么在37°C和5%二氧化碳条件下进行培养，要么皮下移植到Lewis大鼠体内。在1、2、4和8周后，从大鼠体内取出人胰岛片并进行评估。使用双醋酸荧光素（FDA）/碘化丙啶（PI）测量胰岛片的活力，通过葡萄糖刺激胰岛素释放来测量功能，即将胰岛片在低葡萄糖浓度（2.8 mmol/L）下孵育1小时，然后在高葡萄糖浓度（28 mmol/L）下孵育，再在高葡萄糖浓度（28 mmol/L）加3-异丁基-1-甲基黄嘌呤（50μm）的条件下孵育。在长达8周的培养或皮下移植过程中，人胰岛片的活力均保持在70%以上，且功能良好，刺激指数（高葡萄糖浓度下的胰岛素分泌量除以低葡萄糖浓度下的胰岛素分泌量）高于1.5。胰岛移植在1型糖尿病治疗方面不断取得进展。这些初步结果表明，封装的胰岛片在皮下区域的体内环境中能够存活并维持胰岛的活力和功能。
