Khanna Omaditya, Larson Jeffery C, Moya Monica L, Opara Emmanuel C, Brey Eric M
Department of Chemical and Biological Engineering, Illinois Institute of Technology, USA.
J Vis Exp. 2012 Aug 12(66):3388. doi: 10.3791/3388.
Alginate-based materials have received considerable attention for biomedical applications because of their hydrophilic nature, biocompatibility, and physical architecture. Applications include cell encapsulation, drug delivery, stem cell culture, and tissue engineering scaffolds. In fact, clinical trials are currently being performed in which islets are encapsulated in PLO coated alginate microbeads as a treatment of type I diabetes. However, large numbers of islets are required for efficacy due to poor survival following transplantation. The ability to locally stimulate microvascular network formation around the encapsulated cells may increase their viability through improved transport of oxygen, glucose and other vital nutrients. Fibroblast growth factor-1 (FGF-1) is a naturally occurring growth factor that is able to stimulate blood vessel formation and improve oxygen levels in ischemic tissues. The efficacy of FGF-1 is enhanced when it is delivered in a sustained fashion rather than a single large-bolus administration. The local long-term release of growth factors from islet encapsulation systems could stimulate the growth of blood vessels directly towards the transplanted cells, potentially improving functional graft outcomes. In this article, we outline procedures for the preparation of alginate microspheres for use in biomedical applications. In addition, we describe a method we developed for generating multilayered alginate microbeads. Cells can be encapsulated in the inner alginate core, and angiogenic proteins in the outer alginate layer. The release of proteins from this outer layer would stimulate the formation of local microvascular networks directly towards the transplanted islets.
基于藻酸盐的材料因其亲水性、生物相容性和物理结构而在生物医学应用中受到了广泛关注。其应用包括细胞封装、药物递送、干细胞培养和组织工程支架。事实上，目前正在进行临床试验，将胰岛封装在聚赖氨酸（PLO）包被的藻酸盐微珠中作为治疗I型糖尿病的方法。然而，由于移植后存活率低，为达到疗效需要大量的胰岛。局部刺激封装细胞周围微血管网络形成的能力可能通过改善氧气、葡萄糖和其他重要营养物质的运输来提高其存活率。成纤维细胞生长因子-1（FGF-1）是一种天然存在的生长因子，能够刺激血管形成并提高缺血组织中的氧水平。当以持续方式而非单次大剂量给药时，FGF-1的疗效会增强。生长因子从胰岛封装系统中的局部长期释放可以直接刺激血管向移植细胞生长，有可能改善功能性移植物的结果。在本文中，我们概述了用于生物医学应用的藻酸盐微球的制备程序。此外，我们描述了一种我们开发的用于制备多层藻酸盐微珠的方法。细胞可以封装在内部藻酸盐核心中，血管生成蛋白封装在外部藻酸盐层中。来自外层的蛋白质释放将直接刺激朝向移植胰岛的局部微血管网络的形成。
