Coatting NICCs With MSCs and EPCs to Alleviate Instant Blood-Mediated Inflammatory Reaction.

Abstract

Background and aim.Transplantation of islets of porcine is a promising technique for treating insulin-dependent diabetes mellitus (type I). Instant blood-mediated inflammatory reaction (IBMIR) causes rapid islet loss in portal vein islet transplantation. Since it has been all known endothelial progenitor cells (EPCs) can aid neovascularization and protect against complement mediated lysis and activation of coagulation. Mesenchymal stem cells (MSCs) can enhace the viability of NICCs and modulate immune response. Thus we'd like to know when transplantation of the NICC coated with EPCs and MSCs would aggravate the IBMIR or alleviate it ? Research Design and methods. Porcine islets were coated with P2-P4 human umbilicl cord derived MSCs and human cord blood derived EPCs in specially modified culture medium composed of EGM2, porcine serum, IBMX and nicotinamide for 5 days. The capacity of EPCs and MSCs adhere to and grow into porcine islets was analyzed by fluorescence microscopy and confocal scanning microscopy with different cell tracers. The survival and functionality of these composite islets were evaluated by AO/EB and static assay. A negative control group, NICC alone group, and the composite islets group were examined with an in vitro tubing loop assay using human blood. Platelet consumption and complement and coagulation activation were assessed by platelet count, C3a, and thrombin-antithrombin complex (TAT), respectively. Results. MSCs can improve the EPCs coverage compared with EPC islets alone. From the first two days the coverage area was increased rapidly and the majority of NICC can be covered more than 80%. Then they were almost no change at all. Islet survival in vitro and the functionality of the composite islets after culture were almost the same to those of control islets. After incubation with human blood, the composite islets group showed platelet consumption inhibition and low C3a and TAT assay results compared to uncoated controls. Conclusions. Compared to the uncoated controls, the MSCs and EPCs coated NICC could alleviate the IBMIR. And this may because the MSCs can help the EPCs covering the NICC then reduce the exposure of NICC to the human blood. These findings might provide directly applicable tool to enhance the efficacy of islet transplantation in clinical practice.