BIOCOMPATIBLE MEMBRANES FOR ISLET XENOGRAFTS

用于胰岛异种移植物的生物相容性膜

• 批准号: 3243669
• 负责人: Peter B Dervan
• 金额: $ 9.64万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-02-01 至 1996-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3243669
• 关键词: cell adhesion; chemical synthesis; collagen; complement pathway; diabetes mellitus therapy; hamsters; histocompatibility; image enhancement; inflammation; insulin dependent diabetes mellitus; interleukin 1; laboratory rat; macrophage; membrane model; membrane permeability; microcapsule; pancreatic islet transplantation; polylysine; protein biosynthesis; radiotracer; tissue /cell culture; xenotransplantation

Membranes with enhanced biocompatibility will be developed for the immunoisolation of xenogenic islet of Langerhans transplants, and the mechanisms of bioincompatibility will be determined. In a relatively successful technique, a membrane is formed by the coacervation of a polyanionic, water-soluble, nontoxic polymer (algin, a polysaccharide) with a polycationic, water-soluble polymer (polylysine, a polyamino acid). The resulting membrane consists of a hydrogel of mutually entwined, closely interacting negatively and positively charged polymers. Proteins adsorb to this charged membrane and potentiate fibroblast adhesion, spreading, and overgrowth. This process may be initiated or accelerated by inflammation resulting from macrophage spreading and activation on the membrane, which may be stimulated by complement. A novel polymer will be synthesized that has a poly(L-lysine) (abbreviated PLL) backbone with poly(ethylene oxide) (abbreviated PEO) side arms. The polycationic backbone will interact with algin to form a hydrogel membrane, and the nonionic, hydrophilic, PEO side arms will shield the charged surface from the proteins and cells in the biological environment. The permeability and stability of membranes made from coacervates of algin and PLL-graft-PEO will be measured in vitro. Membrane permeance will be assessed by measuring the diffusion of 125I-labeled proteins relative to a mathematical model. Stability in vitro will be assessed by measuring permeance immediately after membrane formation and after 1 month incubation. The biocompatibility of these membranes will be assessed in vitro by measurement of protein adsorption, fibroblast spreading, complement activation, macrophage spreading, and macrophage synthesis of interleukin 1. This will provide insight into the mechanisms of bioincompatibility in these materials. Biocompatibility will be assessed in vivo with islet-free microcapsules in nondiabetic hamsters by measuring the appearance of peritoneal macrophages post-implantation, the attachment of cells to and collagen synthesis upon the microcapsule membranes, and the clumping and incorporation of the microcapsules into the peritoneal tissues. Stability of the capsules in vivo will be assessed by histological examination of peritoneal tissues for broken capsules and by measurement of permeability before implantation and after explantation. Rat islets will be isolated, microencapsulated, and the transplanted intraperitoneally in diabetic golden hamsters. Preliminary in vivo data of 1 month duration with microcapsules made from these materials are presented and lend support to the hypothesis that these microcapsules have enhanced biocompatibility. Microcapsules made with the PLL-graft-PEO material showed dramatically less cell attachment and inflammation than those made with ungrafted PLL.

具有更强的生物相容性的膜将被开发用于 朗格汉斯移植异种胰岛的免疫分离 生物不相容的机制将被确定。在一个相对的 成功的技术，膜是由凝聚形成的 聚阴离子，水溶性，无毒聚合物(藻胶，一种多糖) 一种聚阳离子，可溶于水的聚合物(聚赖氨酸，一种多氨基酸)。这个 得到的膜由相互缠绕的水凝胶组成，紧密地 带负电荷和带正电荷的聚合物相互作用。蛋白质吸附到 这种带电的膜可以增强成纤维细胞的黏附、铺展和 过度生长。炎症可能启动或加速这一过程。 由于巨噬细胞在膜上扩散和激活，这是 可能受到补语的刺激。 将合成一种含有聚(L-赖氨酸)(略)的新型聚合物 PLL)主干和聚氧乙烷(简称PEO)侧臂。这个 聚阳离子骨架将与藻胶相互作用形成水凝胶膜， 非离子的，亲水性的，PEO侧武器将保护带电的 表面来自生物环境中的蛋白质和细胞。这个 海藻胶凝胶膜的透过性和稳定性 PLL-GRAGE-PEO将在体外进行测定。膜透过率将会是 通过测量125I标记的蛋白质相对于 数学模型。体外稳定性将通过测量来评估 成膜后即刻和1个月后的渗透性 孵化。这些膜的生物相容性将在#年进行评估。 通过测量蛋白质吸附，成纤维细胞铺展， 补体激活、巨噬细胞扩散和巨噬细胞合成 白介素1。这将为深入了解 这些材料的生物不相容。将评估生物兼容性 无胰岛微囊在非糖尿病仓鼠体内的测量 种植后腹膜巨噬细胞的形态、附着情况 微囊膜上的细胞和胶原合成，以及 微囊在腹膜内的聚集和结合 纸巾。该胶囊的体内稳定性将通过以下方法进行评估 包膜破损的腹膜组织的组织学检查 植入前和植入后通透性的测定。 大鼠胰岛将被分离、微囊化并移植 糖尿病金黄地鼠的腹膜内注射。日本血吸虫的初步体内数据 用这些材料制成的微胶囊可持续1个月。 支持这样的假设，即这些微胶囊增强了 生物兼容性。用PLL-g-PEO材料制备微胶囊 显示出显著减少的细胞附着和炎症 使用未移植的PLL。