Kumar Manishekhar, Nandi Samit K, Kaplan David L, Mandal Biman B
Biomaterial and Tissue Engineering Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati (IITG), Guwahati, Assam, India.
Department of Veterinary Surgery and Radiology, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India.
ACS Biomater Sci Eng. 2017 Oct 9;3(10):2443-2456. doi: 10.1021/acsbiomaterials.7b00218. Epub 2017 Aug 30.
Pancreatic islet encapsulation in a 3D scaffolding matrix has achieved limited clinical success due to loss of islet function and cell death, shortly after transplantation. Also, transplant-associated inflammatory responses create an unfavorable microenvironment for islet survival. The current study delineates the development of cell-encapsulating immunomodulatory 3D silk scaffolds as bioartificial pancreas (BAP) systems for sustained insulin release. Insulin producing cells were encapsulated inside silk scaffolds with either alginate or agarose for immunoisolation to augment islet survival and function. The scaffolds were extensively characterized for pore architecture, porosity, swelling index, water uptake, and density. Further, suitability of these scaffolds was assessed through diverse tests, including cell adherence, viability, proliferation, 3D spheroid like pancreatic structures development, glucose stimulated insulin secretion, and macrophage polarization. Rat insulinoma (RIN-5) cells were metabolically active within the macroencapsulates and proliferated up to 2.5-fold over 5 weeks in culture. Cultured cells formed 3D islet-like spheroids spontaneously. Primary islets maintained their function in macroencapsulates with enhanced glucose stimulation index when compared to nonencapsulated islets, 1.2 vs 1.7. RT-qPCR and immunohistochemistry results supported the results obtained from glucose challenge assay. Controlled release profiles of anti-inflammatory cytokine interleukine-4 (IL-4) and dexamethasone evinced their prospective application in reducing local foreign body response and immunosuppression. Released IL-4 was biologically active and polarized M0 macrophages to the M2 phenotype, advocating immunosuppressive function. Reduced inflammatory responses illustrated the biocompatibility of these scaffolds. In conclusion, this novel biomaterial system was successfully used to encapsulate insulin-producing cells with enhanced cell functions. Further development of the system may have potential BAP applications.
由于移植后不久胰岛功能丧失和细胞死亡，将胰岛封装在三维支架基质中在临床上取得的成功有限。此外，移植相关的炎症反应为胰岛存活创造了不利的微环境。当前的研究描述了作为用于持续胰岛素释放的生物人工胰腺（BAP）系统的细胞封装免疫调节三维丝支架的开发。将产生胰岛素的细胞封装在含有藻酸盐或琼脂糖的丝支架内以进行免疫隔离，以提高胰岛的存活和功能。对支架的孔隙结构、孔隙率、溶胀指数、吸水率和密度进行了广泛表征。此外，通过多种测试评估了这些支架的适用性，包括细胞粘附、活力、增殖、三维类球体样胰腺结构的发育、葡萄糖刺激的胰岛素分泌和巨噬细胞极化。大鼠胰岛素瘤（RIN-5）细胞在大封装内具有代谢活性，并且在培养5周内增殖了2.5倍。培养的细胞自发形成三维胰岛样球体。与未封装的胰岛相比，原代胰岛在大封装中保持其功能，葡萄糖刺激指数提高，分别为1.2和1.7。RT-qPCR和免疫组织化学结果支持了从葡萄糖激发试验获得的结果。抗炎细胞因子白细胞介素-4（IL-4）和地塞米松的控释曲线表明它们在减少局部异物反应和免疫抑制方面的潜在应用。释放的IL-4具有生物活性，并将M0巨噬细胞极化为M2表型，表明具有免疫抑制功能。炎症反应的减少说明了这些支架的生物相容性。总之，这种新型生物材料系统成功用于封装具有增强细胞功能的胰岛素产生细胞。该系统的进一步开发可能具有潜在的BAP应用。
