Attenuation of senescence progression may be attractive way to preserve the functionality of pancreatic islets (PI) after transplantation. In this study, we developed a model for in vitro induction of premature senescence in rat PI and showed the effectiveness of quercetin (QU) to prevent the senescence. To provide targeted-delivery of QU to the PI after transplantation, we prepared the hybrid clusters (HC) of islet single cells (ISC) and QU-loaded polymeric microspheres (QU; ∼7.55 ng HC^-1). Long-term culture of the HC revealed reduced levels of reactive oxygen species and decreased expression of senescence-associated beta galactosidase, Rb, p53, p16, and p21 compared to that of the control islets. Transplantation of HC into subcutaneous space of the immune-deficient mice produced better glycemic control compared to the control islets or the ICC-transplanted mice. SA-β-Gal staining of the in vivo transplanted HC sample showed lower intensity compared to that of the control islets or the islet cell clusters. Thus, in situ delivery of therapeutic agent may be a promising approach to improve therapeutic outcomes in cell therapy.

Statement of Significance

In this study, we aimed to improve outcomes in islet transplantation using in situ delivery of quercetin to pancreatic islets, using polymeric microspheres. We prepared prolonged release-type microspheres and constructed hybrid clusters of pancreatic islets and the microspheres using hanging drop method. The presence of quercetin in the cellular microenvironment attenuated the progression of senescence in the pancreatic islets in a long-term in vitro culture. Moreover, transplantation of the hybrid clusters in the diabetic mice produced better glycemic control compared to that of the control islets. In addition, quercetin delayed the progression of senescence in the pancreatic islets after in vivo transplantation. Thus, local delivery of antioxidants like quercetin may be an attractive way to improve outcomes in cell therapy.

衰老进程的衰减可能是移植后保留胰岛（PI）功能的有吸引力的方法。在这项研究中，我们开发了一种在大鼠PI中体外诱导早衰的模型，并显示了槲皮素（QU）防止衰老的有效性。为了使QU能够有针对性地传递至PI，我们准备了胰岛单细胞（ISC）和装有QU的聚合物微球（QU;约7.55 ng HC ^-1）的杂合簇（HC））。HC的长期培养表明，与对照胰岛相比，HC的活性氧水平降低，衰老相关的β-半乳糖苷酶，Rb，p53，p16和p21的表达降低。与对照胰岛或ICC移植小鼠相比，将HC移植到免疫缺陷小鼠的皮下空间可产生更好的血糖控制。与对照胰岛或胰岛细胞簇相比，体内移植的HC样品的SA-β-Gal染色显示出较低的强度。因此，原位递送治疗剂可能是改善细胞治疗中治疗效果的有前途的方法。

重要声明

在这项研究中，我们旨在通过使用聚合物微球体将槲皮素原位递送至胰岛来改善胰岛移植的结果。我们制备了延长释放型微球，并使用悬滴法构建了胰岛和微球的杂合簇。在长期体外培养中，细胞微环境中槲皮素的存在减弱了胰岛中衰老的进程。此外，与对照胰岛相比，在糖尿病小鼠中杂交簇的移植产生了更好的血糖控制。此外，槲皮素可延缓体内胰岛的衰老进程移植。因此，抗氧化剂如槲皮素的局部递送可能是改善细胞治疗结果的一种有吸引力的方法。