ABSTRACT
Islet transplantation is a promising treatment of diabetes mellitus and its complications. Nevertheless, dysfunction post-transplantation, rejection and shortage of donors are the bottleneck issues in the field of islet transplantation. Optimizing the preservation method of pancreas plays a positive role in obtaining a sufficient quantity of effective islets and maintaining their functions. During the culture stage, anti-rejection and anti-apoptosis treatment of islets, including mesenchymal stem cell (MSC), MSC-derived exosomes, anti-apoptosis drugs and gene modification, may become major approaches for islet protection and functional maintenance in clinical islet transplantation. Use of anti-instant blood-mediated inflammatory reaction (IBMIR) drugs after islet transplantation also plays a critical role in protecting islet function. In this article, the whole process from islet preparation to islet transplantation was illustrated, and relevant strategies of islet protection and functional maintenance were reviewed, aiming to provide reference for improving the quality of donors to compensate for the shortage of absolute quantity of donors and elevating the efficiency of islet transplantation.
ABSTRACT
As an effective procedure for type 1 diabetes mellitus and end-stage type 2 diabetes mellitus, islet transplantation could enable those patients to obtain proper control of blood glucose levels. Instant blood-mediated inflammatory reaction (IBMIR) is a nonspecific inflammation during early stage after islet transplantation. After IBMIR occurs, coagulation cascade, complement system activation and inflammatory cell aggregation may be immediately provoked, leading to loss of a large quantity of transplant islets, which severely affects clinical efficacy of islet transplantation. How to alleviate the islet damage caused by IBMIR is a hot topic in islet transplantation. Heparin and etanercept, an inhibitor of tumor necrosis factor-α, are recommended as drugs for treating IBMIR following islet transplantation. Recent studies have demonstrated that multiple approaches and drugs may be adopted to mitigate the damage caused by IBMIR to the islets. In this article, the findings in clinical and preclinical researches were reviewed, aiming to provide reference for the management of IBMIR after islet transplantation.
ABSTRACT
OBJECTIVES@#Heparin is mainly used as an anticoagulant in clinic, and it also has a certain anti-inflammatory effect. At present, after portal vein islet transplantation in diabetic patients, heparin is mainly infused through the peripheral veins of the limbs to achieve the purpose of anticoagulation and protection of the graft, rather than through the portal vein. In this study, animal experiments were conducted to investigate the effect of heparin infusion via the portal vein and marginal ear vein on the instant blood-mediated inflammatory reaction (IBMIR) after portal vein islet transplantation, which is the choice of anticoagulation methods for clinical islet transplantation to provide a basis for decision-making.@*METHODS@#A total of 50 neonatal pigs (Xeno-1 type, 3-5 days) were selected. Islets were isolated and purified from the pancreas of neonatal pigs. Ten non-diabetic Landrace pigs (1.5-2.0 months) served as recipients, and 12 000 IEQ/kg neonatal porcine islets were transplanted into the liver through the portal vein. All recipients received bolus injection of 50 U/kg of heparin 10 minutes before transplantation. After the bolus injection of heparin, the experimental group received heparin via the portal vein [10 U/(kg·h), 5 recipients], and the control group received heparin via the marginal ear vein [10 U/(kg·h), 5 recipients]. The superior vena cava blood was collected from the 2 groups pre-operation at 1, 3, 24 h post-operation of the transplantation. The portal vein blood was collected from the experimental group at 1 and 3 h after the transplantation as well. The levels of complement C3a, C5a, thrombin-antithrombin complex (TAT), β-thromboglobulin (β-TG), and D-dimer as well as activated partial thromboplastin time (APTT) in superior vena cava blood from 1 and 3 h post-transplantation were detected in the 2 groups, and the levels of anti-Xa and anti-IIa in the portal vein and superior vena cava blood from 1 and 3 h post-transplantation in the experimental group were detected. Twenty four hours after the transplantation, the liver tissues in the 2 groups were collected for pathological examination to observe the inflammatory cell infiltration and peripheral thrombosis around the islets graft in liver.@*RESULTS@#Before transplantation, there was no statistically significant difference in C3a, C5a, TAT, β-TG, D-dimer levels and APTT between the 2 groups (all P>0.05). At 1 and 3 h after transplantation, the C3a, TAT, and D-dimer levels in the experimental group were significant decreased than those in the control groups (all P<0.05), and at 3 h after transplantation the C5a was significant decreased than that in the control group (P<0.05). At 1 and 3 h after transplantation, the anti-Xa and anti-IIa levels in the portal vein blood were significantly increased than those in the superior vena cava blood in the experimental group (all P<0.05). Pathological results showed the presence of islet cell clusters in the liver blood vessels. The thrombus formation and neutrophil infiltration around islet graft was not obvious in the experimental group, while massive thrombus formation and neutrophil infiltration in the control group.@*CONCLUSIONS@#Compared with marginal ear vein infusion of heparin, the direct infusion of heparin in the portal vein has a certain inhibitory effect on complement system, coagulation system activation and inflammatory cell infiltration in portal vein islet transplantation, which may attenuate the occurrence of IBMIR.
Subject(s)
Animals , Humans , Anticoagulants/therapeutic use , Heparin/therapeutic use , Islets of Langerhans/pathology , Islets of Langerhans Transplantation/physiology , Portal Vein , Swine , Vena Cava, SuperiorABSTRACT
Objective To validate whether the expression of human cluster of differentiation 55 (hCD55) protein in porcine islet cells could inhibit the activation of complement components in human serum. Methods Four adult pigs with WT (wild type), GTKO [α-1, 3-galactosyltransferase (GGTA1) knockout], GTKO/hCD55 and hCD55 genotypes were selected. Islet cells were isolated from WT, GTKO and GTKO/hCD55 pigs, and the purity and insulin secretion function were detected. The expression of hCD55 at the DNA, RNA and protein levels was analyzed by agarose gel electrophoresis, reverse transcription polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Complement-dependent cytotoxicity assay and complement deposition assay were performed under the incubation conditions with fresh human serum. Results The purity of isolated porcine islet cells from three genotype pigs was > 75%, and the glycemic index was > 1. The expression of hCD55 messenger RNA(mRNA) and protein in GTKO/hCD55 porcine islet cells decreased the deposition of human complement component C3c and membrane-attacking complex C5b-9, and reduced the cytotoxicity. Conclusions The expression of hCD55 protein in porcine islet cells could inhibit the activation of human complement and reduce complement-mediated killing effect, indicating that hCD55 protein could exert complement protection effect on porcine islet cells. These findings provide theoretical basis for the application of hCD55 in islet xenotransplantation.
ABSTRACT
Diabetes mellitus is increasing all over the world and is a serious health problem. Pancreatic islet transplantation is promising treatment for diabetes mellitus, but an imbalance between deceased pancreas donors and recipients limited the widespread clinical application. Therefore, pig islets could be used as an alternative islet source in transplantation. However, a big hurdle to clinical application of islet xenotransplantation is the instant blood mediated inflammatory reaction (IBMIR), which is characterized by activation of the coagulation cascade, platelets and complement systems. Innate immune cells infiltrate the islets in the process of IBMIR and thereby accelerate the early graft loss. Characteristics of IBMIR in islet xenotransplantion are very different from the rejection in solid organ xenotransplantation. Therefore, we focus on the molecules for surmounting IBMIR in order to accomplish successful islet xenotransplantation. To prevent the IBMIR in islet xenotransplantation, development of genetic modified pigs containing anti-coagulant, anti-thrombosis and complement regulatory genes, or capsulation of islet with biomaterials for blocking immune response around islet surface can be tried. Galpha-Gal knockout pigs and the diverse transgenic pigs for complement regulatory protein or anti-coagulant genes have been developed for xenotransplantation. This review summarized on characteristics of rejection in islet xenotransplantation and discusses the strategies for overcoming the rejection.