Intraportal Islet Transplantation Research Articles

The Adrenal Gland and Pancreatic Islets - A Beneficial Endocrine Alliance.

Intraportal islet transplantation in patients with type 1 diabetes enables restoration of glucose-regulated insulin secretion. However, several factors hamper a widespread application and long-term success: chronic hypoxia, an inappropriate microenvironment and suppression of regenerative and proliferative potential by high local levels of immunosuppressive agents. Therefore, the identification of alternative and superior transplant sites is of major scientific and clinical interest. Here, we aim to evaluate the adrenal as an alternative transplantation site. The adrenal features a particular microenvironment with extensive vascularization, anti-apoptotic and pro-proliferative, anti-inflammatory and immunosuppressive effects. To validate this novel transplantation site, an in vitro co-culture system of adrenal cells and pancreatic islets was established and viability, islet survival, functional potency and antioxidative defense capacity were evaluated. For in vivo validation, an immune-deficient diabetic mouse model for intra-adrenal islet transplantation was applied. The functional capacity of intra-adrenally grafted islets to reverse diabetes was compared to a standard islet transplant model and measures of engraftment such as vascular integration were evaluated. The presence of adrenal cells positively impacted on cell metabolism and oxidative stress. Following transplantation, we could demonstrate enhanced islet function in comparison to standard models with improved engraftment and superior re-vascularization. This experimental approach allows for novel insights into the interaction of endocrine systems and may open up novel strategies for islet transplantation augmented through the bystander effect of other endocrine cells or the active factors secreted by adrenal cells modulating the microenvironment.

Functional maturation and longitudinal imaging of intraportal neonatal porcine islet grafts in genetically diabetic pigs

Allogeneic intraportal islet transplantation (ITx) has become an established treatment for patients with poorly controlled type 1 diabetes. However, the loss of viable beta-cell mass after transplantation remains a major challenge. Therefore, noninvasive imaging methods for long-term monitoring of the transplant fate are required. In this study, [68Ga]Ga-DOTA-exendin-4 positron emission tomography/computed tomography (PET/CT) was used for repeated monitoring of allogeneic neonatal porcine islets (NPI) after intraportal transplantation into immunosuppressed genetically diabetic pigs. NPI transplantation (3.3000-15.0000 islet equivalents per kg body weight) led to a reduced need for exogenous insulin therapy and finally normalization of blood glucose levels in 3 out of 4 animals after 5 to 10 weeks. Longitudinal PET/CT measurements revealed a significant increase in standard uptake values in graft-bearing livers. Histologic analysis confirmed the presence of well-engrafted, mature islet clusters in the transplanted livers. Our study presents a novel large animal model for allogeneic intraportal ITx. A relatively small dose of NPIs was sufficient to normalize blood glucose levels in a clinically relevant diabetic pig model. [68Ga]Ga-DOTA-exendin-4 PET/CT proved to be efficacious for longitudinal monitoring of islet transplants. Thus, it could play a crucial role in optimizing ITx as a curative therapy for type 1 diabetes.

Adipose-Derived Stromal Cells Preserve Pancreatic Islet Function in a Transplantable 3D Bioprinted Scaffold.

Intra-portal islet transplantation is currently the only clinically approved beta cell replacement therapy, but its outcome is hindered by limited cell survival due to a multifactorial reaction against the allogeneic tissue in liver. Adipose-derived stromal cells (ASCs) can potentially improve the islet micro-environment by their immunomodulatory action. The challenge is to combine both islets and ASCs in a relatively easy and consistent long-term manner in a deliverable scaffold. Manufacturing the 3D bioprinted double-layered scaffolds with primary islets and ASCs using a mix of alginate/nanofibrillated cellulose (NFC) bioink is reported. The diffusion properties of the bioink and the supportive effect of human ASCs on islet viability, glucose sensing, insulin secretion, and reducing the secretion of pro-inflammatory cytokines are demonstrated. Diabetic mice transplanted with islet-ASC scaffolds reach normoglycemia seven days post-transplantation with no significant difference between this group and the group received islets under the kidney capsules. In addition, animals transplanted with islet-ASC scaffolds stay normoglycemic and show elevated levels of C-peptide compared to mice transplanted with islet-only scaffolds. The data present a functional 3D bioprinted scaffold for islets and ASCs transplanted to the extrahepatic site and suggest a possible role of ASCs on improving the islet micro-environment.

118.5: Insulin independence after intraportal islet transplantation in patients with kidney allograft and type 1 diabetes mellitus

118.5: Insulin independence after intraportal islet transplantation in patients with kidney allograft and type 1 diabetes mellitus

240-OR: Islet Allotransplantation into Prevascularized Sernova Cell Pouch—Early Results from the University of Chicago

Each of 6 patients with T1DM and problematic hypoglycemia received 2 islet transplants into pre-implanted Sernova Cell Pouches (SCPs). Each procedure involved transplantation of islets into two 8-channel SCPs and one mini sentinel SCP. SCP implants and the combination of SCP with human cadaveric islets are both well tolerated with durations exceeding 3 years. Detectable islet function (≥0.3ng/ml peak serum c-peptide in mixed meal tolerance test) was achieved in 4 patients following islet transplant to SCP. It was correlated with transplanted islet mass of 300k-500k IEQ per procedure. Transplantation of islet mass <300k IEQ did not lead to detectable c-peptide secretion. C-peptide was detectable for periods ranging from days up to 12 months after the procedure. Three patients with suboptimal levels of immunosuppression due to non-compliance experienced antibody mediated rejection based on de novo donor specific antibodies (DSAs). One patient with DSAs had detectable stimulated c-peptide at 90 days post-transplant. Histological assessment of sentinel SCPs retrieved ≥90 days post-transplant revealed surviving functional islets within vascularized SCP channels via positive immunofluorescence staining of insulin, c-peptide, glucagon and somatostatin in 5 of 6 patients. Five patients received supplemental intraportal islet transplants (IPITx) and all of them remain insulin independent (>2.5Y, >1Y, 10M, 2M, 1M). The sixth patient is awaiting an IPITx in the coming months as per protocol. Safety and dose-response observations from the first cohort of 6 patients led to the implementation of 10-channel SCPs with 50% greater transplant capacity than the 8-channel configuration in a second study cohort. Two additional patients were recently implanted with 10-channel SCPs and are currently awaiting their first islet transplantation. Disclosure M.Ogledzinski: None. L.Wang: None. M.Tibudan: None. R.Barth: None. J.Fung: None. P.Witkowski: Advisory Panel; Vertex Pharmaceuticals Incorporated, Novartis. S.Gondek: None. W.Lin: None. K.Milejczyk: None. B.Juengel: None. L.Potter: None. P.J.Bachul: None. L.Basto: None. L.Perea: None. Funding Sernova; JDRF

1498-P: Preemptive Insulin Supplementation for Islet Graft Protection, Optimal Blood Glucose Control, and Fetal Development during the Pregnancy in Insulin-Independent Patient after Islet Transplantation

Pregnancy increases metabolic demand for insulin, which may lead to the exhaustion of intraportally transplanted islets and postgestational hyperglycemia. Here we report a successful long-term preservation of islet graft function after two subsequent pregnancies while applying preemptive insulin supplementation. 29-year-old female with T1DM achieved long-term insulin independence with HbA1c <5.8% after a single intraportal islet transplant. Before conception, mycophenolate was replaced with azathioprine and tacrolimus target trough level was decreased to 4-6ng/ml. The patient became pregnant twice, 5 years and 7.5 years after her islet transplantation. During the first and second pregnancy patient preemptively supplemented with insulin up to 35-70u/day and up to 35 units daily, respectively to target fasting blood glucose below 90mg/ml. Postpartum the patient was successfully weaned off insulin maintaining optimal blood glucose control with HbA1c below 5.7%. Islet graft function before and after the pregnancy remained optimal as reflected by BETA-2 above 17 and comparable c-peptide secretion and peak blood glucose levels below 130mg/ml during the 8.5-year follow-up in Mixed Meal Tolerance Test. Both newborns were premature and delivered at 34 weeks with emergent c-sections due to preeclampsia. Unfortunately, the first newborn died due to necrotizing enterocolitis. The second child has been developing appropriately up-to-date three months after her birth. Our report confirms that insulin supplementation during pregnancy in insulin-independent patients after islet transplantation was safe and effective in maintaining optimal blood glucose control and islet graft function in the long term. It also underscores the high-risk nature of pregnancy in islet transplant recipients and the need for close clinical monitoring. Disclosure S.Gondek: None. L.Wang: None. M.Tibudan: None. R.Barth: None. J.Fung: None. P.Witkowski: Advisory Panel; Vertex Pharmaceuticals Incorporated, Novartis. M.Ogledzinski: None. W.Lin: None. K.Milejczyk: None. B.Juengel: None. L.Potter: None. P.J.Bachul: None. L.Basto: None. L.Perea: None.

Pancreatic Islet Transplantation into the Submandibular Gland: Our Experimental Experience and a Review of the Relevant Literature.

Pancreatic islet transplantation is a promising therapy for type 1 diabetes. Islet transplantation is clinically performed through intra-portal infusion, which is associated with several drawbacks, including poor engraftment. The histological resemblance between the submandibular gland and the pancreas renders it an attractive alternative site for islet transplantation. In this study, we refined the technique of islet transplantation into the submandibular gland to achieve good morphological features. Then, we transplanted 2600 islet equivalents into the submandibular glands of diabetic Lewis rats. Intra-portal islet transplantation was performed in diabetic rats as a control. Blood glucose levels were followed for 31 days, and an intravenous glucose tolerance test was performed. Immunohistochemistry was used to demonstrate the morphology of transplanted islets. Follow-up after transplantation showed that diabetes was cured in 2/12 rats in the submandibular group in comparison to 4/6 in the control group. The intravenous glucose tolerance test results of the submandibular and intra-portal groups were comparable. Immunohistochemistry showed large islet masses in the submandibular gland in all examined specimens with positive insulin staining. Our results show that submandibular gland tissue can support the islet function and engraftment but with considerable variability. Good morphological features were achieved using our refined technique. However, islet transplantation into rat submandibular glands did not demonstrate a clear advantage over conventional intra-portal transplantation.

Research Highlights.

Research Highlights.

Noninvasive quantitative evaluation of viable islet grafts using 111 In-exendin-4 SPECT/CT.

Islet transplantation (IT) is an effective β-cell replacement therapy for patients with type 1 diabetes; however, the lack of methods to detect islet grafts and evaluate their β-cell mass (BCM) has limited the further optimization of IT protocols. Therefore, the development of noninvasive β-cell imaging is required. In this study, we investigated the utility of the 111 Indium-labeled exendin-4 probe {[Lys12(111In-BnDTPA-Ahx)] exendin-4} (111 In exendin-4) to evaluate islet graft BCM after intraportal IT. The probe was cultured with various numbers of isolated islets. Streptozotocin-induced diabetic mice were intraportally transplanted with 150 or 400 syngeneic islets. After a 6-week observation following IT, the ex-vivo liver graft uptake of 111 In-exendin-4 was compared with the liver insulin content. In addition, the in-vivo liver graft uptake of 111 In exendin-4 using SPECT/CT was compared with that of liver graft BCM measured by a histological method. As a result, probe accumulation was significantly correlated with islet numbers. The ex-vivo liver graft uptake in the 400-islet-transplanted group was significantly higher than that in the control and the 150-islet-transplanted groups, consistent with glycemic control and liver insulin content. In conclusion, in-vivo SPECT/CT displayed liver islet grafts, and uptakes were corroborated by histological liver BCM. 111 In-exendin-4 SPECT/CT can be used to visualize and evaluate liver islet grafts noninvasively after intraportal IT.

Ideal Duration of Pretreatment Using a Gelatin Hydrogel Nonwoven Fabric Prior to Subcutaneous Islet Transplantation.

Subcutaneous islet transplantation is a promising treatment for severe diabetes; however, poor engraftment hinders its prevalence. We previously revealed that a gelatin hydrogel nonwoven fabric (GHNF) markedly improved subcutaneous islet engraftment in comparison with intraportal islet transplantation. We herein investigated whether the duration of pretreatment using GHNF affected the outcome of subcutaneous islet transplantation. A silicone spacer with GHNF was implanted into the subcutaneous space of healthy mice at 2, 4, 6, or 8 weeks before transplantation, and then diabetes was induced 7 days before transplantation. Syngeneic islets were transplanted into the pretreated space. Blood glucose, intraperitoneal glucose tolerance, immunohistochemistry, inflammatory mediators, and gene expression were evaluated. The 6-week group showed significantly better blood glucose changes than the other groups (P < 0.05). The cure rate of the 6-week group (60.0%) was the highest among the groups (2-week = 0%, 4-week = 50.0%, 8-week = 15.4%). The number of von Willebrand factor (vWF)-positive vessels in the 6-week group was significantly higher than in the other groups at pre-islet and post-islet transplantation (P < 0.01 [vs 2-and 4-week groups] and P < 0.05 [vs all other groups], respectively). Notably, this beneficial effect was also observed when GHNF was implanted into diabetic mice injected with streptozotocin 7 days before GHNF implantation. The positive rates for laminin, collagen III, and collagen IV increased as the duration of pretreatment became longer and were significantly higher in the 8-week group (P < 0.01). Inflammatory mediators, including interleukin (IL)-1b, granulocyte colony-stimulating factor (G-CSF), and interferon (IFN)-γ, were gradually downregulated according to the duration of GHNF pretreatment and re-elevated in the 8-week group. Taken together, the duration of GHNF pretreatment apparently had an impact on the outcomes of subcutaneous islet transplantation, and 6 weeks appeared to be the ideal duration. Islet graft revascularization, extracellular matrix compensation of the islet capsule, and the inflammatory status at the subcutaneous space would be crucial factors for successful subcutaneous islet transplantation.

2022 Canadian Surgery Forum Sept. 15–17, 202201. Operative classification of ventral abdominal hernias: new and practical classification02. Watchful waiting for large primary splenic cysts03. Transversus abdominis plane (TAP) blocks with and without dexamethasone in colorectal surgery04. What factors determine publication of resident research day projects?05. Characterization of near-infrared imaging and indocyanine green use amongst general surgeons06. Variation in opioid prescribing

# 01. Operative classification of ventral abdominal hernias: new and practical classification {#article-title-2} Ventral hernias of the abdomen are defined as a noninguinal, nonhiatal defect in the fascia of the abdominal wall. Unfortunately, there is not currently a universal classification system

334.2: A Gelatin Hydrogel Nonwoven Fabric Improves Outcomes of Subcutaneous Islet Transplantation

Introduction: Subcutaneous islet transplantation is a promising treatment for severe diabetes, since it has several advantages, including minimal invasiveness and easy accessibility for the islet grafts, which makes it possible to monitor and/or remove islet grafts if needed. However, poor vascularization has long been regarded as major drawback in this transplant site. Recently, several groups have reported that the compensation of extracellular matrices (ECM) is also crucial for successful subcutaneous transplantation. We previously reported that a recombinant peptide (RCP) enhances subcutaneous islet engraftment. However, it is impractical for clinical use because RCP must be removed when transplanting islets. We herein investigated whether a novel bioabsorbable gelatin hydrogel nonwoven fabric (GHNF) could improve subcutaneous islet engraftment. Methods: A silicon spacer with or without GHNF was implanted into the subcutaneous space of diabetic mice at 6 weeks before islet transplantation. Syngeneic islets (400 islet equivalents) were transplanted into the pretreated space or intraportally (Ipo group). Blood glucose, intraperitoneal glucose tolerance, immunohistochemistry, CT angiography and gene expression were evaluated. Results: The cure rate (Figure 1) and glucose tolerance of the GHNF group were significantly better than in the control and Ipo groups (p<0.01, p<0.05, respectively). In the GHNF group, a limited increase of vWF-positive vessels was detected in the islet capsule, whereas laminin (p<0.05), collagen III and IV were considerably enhanced. CT angiography revealed that the blood vessel volume surrounding the silicon spacer was comparable between the GHNF and control groups. TaqMan arrays revealed a significant upregulation of 19 target genes (including insulin-like growth factor-2(IGF-2)) in the pretreated space (p<0.05) (Figure 2). The protein level of IGF-2 in the supernatant of the homogenized subcutaneous fibrous capsules in the GHNF group was also significantly higher than that in the control group. Conclusions: Pre-implantation of a GHNF effectively improved subcutaneous islet engraftment, resulting in much better outcomes in comparison to intraportal islet transplantation. This beneficial effect may be mainly due to the compensation of ECM for the islet capsule and protection of islet viability by various growth factors, rather than the enhancement of neovascularization. This study was supported by a Japanese Grant-in-Aid for Scientific Research (A) (Grant Number 18H04056) from the Japan Society for the Promotion of Science. This study was supported by AMED under Grant Number JP19bm0404043. The authors thank Kozue Imura and Megumi Goto (Division of Transplantation and Regenerative Medicine, Tohoku University) for their excellent technical assistance. The authors also acknowledge the support of the Biomedical Research Core of Tohoku University, Graduate School of Medicine and TAMRIC (Tohoku Advanced Medical Research and Incubation Center).

Beta-Cell Golgi Stress Response to Lipotoxicity and Glucolipotoxicity: A Preliminary Study of a Potential Mechanism of Beta-Cell Failure in Posttransplant Diabetes and Intraportal Islet Transplant.

Lipotoxicity and glucolipotoxicity are among the mostimportanttriggers of beta-cell failure in patients with type 2 and posttransplant diabetes. Because the Golgi apparatus is a vital organelle in secretory cells like beta cells, its behavior under stress conditions determines the cell's functional capacity. To mimic lipotoxicity and glucolipotoxicity as metabolic stresses for beta-cell failure, rat insulinoma INS-1E cells were treated with palmitic acid, glucose, or both. Cells were cultured in the presence of 5.0, 16.7, or 33 mM glucose with or without 0.5 mM palmitic acid for 8, 16, 24, and 48 hours. Incubation in the presence of any of the 3 concentrations of glucose with 0.5 mM palmitic acid provided glucolipotoxicity. In addition to the endoplasmic reticulum stress marker (Hspa5), we evaluated changes in Golgi function under experimental metabolic stresses. In doing this, we measured expression levels of the genes coding Golgi structural proteins (Acbd3,Golga2, and Arf1), Golgi glycosylation enzymes sialyltransferaz10 and sialyltransferase 1 (St3gal1), and Golgi stress mediators (Creb3 and Arf4). Golgi responded to lipotoxicity and glucolipotoxicity by increasing the expression of St3gal1 (P = .05 in both conditions) and Creb3 (P = .022 and P = .01, respectively). The Arf4 gene transcript also increased in glucolipotoxic media (P = .03). Glucotoxicity alone did not induce a change in the transcript levels of Creb3 and Arf4. Lipotoxicity and glucolipotoxicity induced Creb3 and Arf4 expression, which are important Golgi stress response mediators leading to apoptosis. This preliminary study showed that the Golgi stress response is important in lipotoxic and glucolipotoxic conditions in terms of beta-cell failure. Solving the mystery of intracellular molecular mechanisms leading to beta-cell dysfunction is crucial to understanding the pathophysiology of posttransplant diabetes and most probably the failure of intraportal islet transplants in the long term.

Outcomes Following Extrahepatic and Intraportal Pancreatic Islet Transplantation: A Comparative Cohort Study.

Preliminary studies show promise for extrahepatic islet transplantation (ITx). However, clinical comparisons with intraportal ITx outcomes remain limited. This single-center cohort study evaluates patients receiving extrahepatic or intraportal ITx between 1999 and 2018. Primary outcome was stimulated C-peptide level. Secondary outcomes were fasting plasma glucose, BETA-2 scores, and fasting C-peptide level. Multivariable logistic modeling evaluated factors independently associated with a composite variable of early graft failure and primary nonfunction within 60 d of ITx. Of 264 patients, 9 (3.5%) received extrahepatic ITx (gastric submucosal = 2, subcutaneous = 3, omental = 4). Group demographics were similar at baseline (age, body mass index, diabetes duration, and glycemic control). At 1-3 mo post-first infusion, patients receiving extrahepatic ITx had significantly lower stimulated C-peptide (0.05 nmol/L versus 1.2 nmol/L, P < 0.001), higher fasting plasma glucose (9.3 mmol/L versus 7.3 mmol/L, P < 0.001), and lower BETA-2 scores (0 versus 11.6, P < 0.001) and SUITO indices (1.5 versus 39.6, P < 0.001) compared with those receiving intraportal ITx. Subjects receiving extrahepatic grafts failed to produce median C-peptide ≥0.2 nmol/L within the first 60 d after transplant. Subsequent intraportal infusion following extrahepatic transplants achieved equivalent outcomes compared with patients receiving intraportal transplant alone. Extrahepatic ITx was independently associated with early graft failure/primary non-function (odds ratio 1.709, confidence interval 73.8-39 616.0, P < 0.001), whereas no other factors were independently predictive. Using current techniques, intraportal islet infusion remains the gold standard for clinical ITx, with superior engraftment, graft function, and glycemic outcomes compared with extrahepatic transplantation of human islets.

The Influence of Microenvironment on Survival of Intraportal Transplanted Islets.

Clinical islet transplantation has the potential to cure type 1 diabetes. Despite recent therapeutic success, it is still uncommon because transplanted islets are damaged by multiple challenges, including instant blood mediated inflammatory reaction (IBMIR), inflammatory cytokines, hypoxia/reperfusion injury, and immune rejection. The transplantation microenvironment plays a vital role especially in intraportal islet transplantation. The identification and targeting of pathways that function as “master regulators” during deleterious inflammatory events after transplantation, and the induction of immune tolerance, are necessary to improve the survival of transplanted islets. In this article, we attempt to provide an overview of the influence of microenvironment on the survival of transplanted islets, as well as possible therapeutic targets.

Subcutaneous nanotherapy repurposes the immunosuppressive mechanism of rapamycin to enhance allogeneic islet graft viability.

Standard oral rapamycin (i.e. Rapamune®) administration is plagued by poor bioavailability and broad biodistribution. Thus, this pleotropic mTOR inhibitor has a narrow therapeutic window, numerous side effects and provides inadequate protection to transplanted cells and tissues. Furthermore, the hydrophobicity of rapamycin limits its use in parenteral formulations. Here, we demonstrate that subcutaneous delivery via poly(ethylene glycol)-b-poly(propylene sulfide)(PEG-b-PPS) polymersome (PS) nanocarriers significantly alters rapamycin’s cellular biodistribution to repurpose its mechanism of action for tolerance instead of immunosuppression while minimizing side effects. While oral rapamycin inhibits naïve T cell proliferation directly, subcutaneously administered rapamycin-loaded polymersomes (rPS) modulate antigen presenting cells in lieu of T cells significantly improving maintenance of normoglycemia in a clinically relevant, MHC-mismatched, allogeneic, intraportal (liver) islet transplantation model. These results demonstrate the ability of a rationally designed nanocarrier to re-engineer the immunosuppressive mechanism of a drug by controlling cellular biodistribution.

Autologous regulatory T cells in clinical intraportal allogenic pancreatic islet transplantation.

Allogeneic islet transplantation in type 1 diabetes requires lifelong immunosuppression to prevent graft rejection. This medication can cause adverse effects and increases the susceptibility for infections and malignancies. Adoptive therapies with regulatory T cells (Tregs) have shown promise in reducing the need for immunosuppression in human transplantation settings but have previously not been evaluated in islet transplantation. In this study, five patients with type 1 diabetes undergoing intraportal allogeneic islet transplantation were co-infused with polyclonal autologous Tregs under a standard immunosuppressive regimen. Patients underwent leaukapheresis from which Tregs were purified by magnetic-activated cell sorting (MACS) and cryopreserved until transplantation. Dose ranges of 0.14-1.27×106 T cells per kilo bodyweight were transplanted. No negative effects were seen related to the Treg infusion, regardless of cell dose. Only minor complications related to the immunosuppressive drugs were reported. This first-in-man study of autologous Treg infusion in allogenic pancreatic islet transplantation shows that the treatment is safe and feasible. Based on these results, future efficacy studies will be developed under the label of advanced therapeutic medical products (ATMP), using modified or expanded Tregs with the aim of minimizing the need for chronic immunosuppressive medication in islet transplantation.

P.101: Safety and Efficacy of a Percutaneous Intraportal Islet Transplantation Procedure Using Tract Embolization With Gelatine Foam Pledgets

Introduction: Intraportal pancreatic islet transplantation is a minimally invasive procedure to treat patients with diabetes mellitus and unstable glycemic control despite optimal medical treatment. We analysed the safety and efficacy of percutaneous transhepatic intraportal islet transplantation procedures using embolization of the hepatic puncture tract with gelatin foam pledgets. Methods: This was a retrospective, single center study including all allogeneic islet transplantations between 2007 and 2019 at the Leiden University Medical Center. Under local anaesthesia, islets were infused into the main portal vein using a right-sided transhepatic approach. Tract embolization was performed in 51/62 procedures using the Hunter Biopsy Sealing Device. Complications were assessed according to CTCAEv5.0. Stimulated C-peptide during a mixed meal test was measured after 3 months to evaluate efficacy. Results: A total of 62 islet transplants in 38 recipients (female 39.5%; median age 53.2 (IQR 40.8 – 64.0) years) were included. 11 complications occurred in 62 procedures: no CTCAE grade 4 or 5 complications occurred. Bleeding occurred in 3/11 (27.3%) of procedures without tract embolization, compared to 2/51 (3.9%) with tract embolization (p=0.01). 3 of these bleeding episodes comprised grade 3 complications which could be managed conservatively, and 2 bleeding episodes were grade 1 that did not require intervention. More than one puncture attempt was a positive predictor for bleeding (p=0.001) and pain (p=0.002). No portal vein thromboses were encountered.1 biliary puncture (grade 1) and 5 episodes of pain (grade 1 (n=3) and grade 2 (n=2)) occurred. Three months after infusion, stimulated C-peptide was >0.17 nmol/L in 60/62 (97%) transplant recipients. Conclusion: A percutaneous transhepatic procedure using gelatine foam pledgets is a safe and efficacious method to transplant islets into the portal vein. Complications were either self-limiting or could be managed with non-invasive treatment. The vast majority of patients gained endogenous insulin production.

Heterogeneity and neurovascular integration of intraportally transplanted islets revealed by 3-D mouse liver histology.

Intraportal islet transplantation has been clinically applied for treatment of unstable type 1 diabetes. However, in the liver, systematic assessment of the dispersed islet grafts and the graft-hepatic integration remains difficult, even in animal models. This is due to the lack of global and in-depth analyses of the transplanted islets and their microenvironment. Here, we apply three-dimensional (3-D) mouse liver histology to investigate the islet graft microstructure, vasculature, and innervation. Streptozotocin-induced diabetic mice were used in syngeneic intraportal islet transplantation to achieve euglycemia. Optically cleared livers were prepared to enable 3-D morphological and quantitative analyses of the engrafted islets. 3-D image data reveal the clot- and plaque-like islet grafts in the liver: the former are derived from islet emboli and associated with ischemia, whereas the latter (minority) resemble the plaques on the walls of portal vessels (e.g., at the bifurcation) with mild, if any, perigraft tissue damage. Three weeks after transplantation, both types of grafts are revascularized, yet significantly more lymphatics are associated with the plaque- than clot-like grafts. Regarding the islet reinnervation, both types of grafts connect to the periportal nerve plexus and develop peri- and intragraft innervation. Specifically, the sympathetic axons and varicosities contact the α-cells, highlighting the graft-host neural integration. We present the heterogeneity of the intraportally transplanted islets and the graft-host neurovascular integration in mice. Our work provides the technical and morphological foundation for future high-definitional 3-D tissue and cellular analyses of human islet grafts in the liver.NEW & NOTEWORTHY Modern 3-D histology identifies the clot- and plaque-like islet grafts in the mouse liver, which otherwise cannot be distinguished with the standard microtome-based histology. The two types of grafts are similar in blood microvessel density and sympathetic reinnervation. Their differences, however, are their locations, severity of associated liver injury, and access to lymphatic vessels. Our work provides the technical and morphological foundation for future high-definitional 3-D tissue/cellular analyses of human islet grafts in the liver.

Stem Cell-Based Clinical Trials for Diabetes Mellitus.

Since its introduction more than twenty years ago, intraportal allogeneic cadaveric islet transplantation has been shown to be a promising therapy for patients with Type I Diabetes (T1D). Despite its positive outcome, the impact of islet transplantation has been limited due to a number of confounding issues, including the limited availability of cadaveric islets, the typically lifelong dependence of immunosuppressive drugs, and the lack of coverage of transplant costs by health insurance companies in some countries. Despite improvements in the immunosuppressive regimen, the number of required islets remains high, with two or more donors per patient often needed. Insulin independence is typically achieved upon islet transplantation, but on average just 25% of patients do not require exogenous insulin injections five years after. For these reasons, implementation of islet transplantation has been restricted almost exclusively to patients with brittle T1D who cannot avoid hypoglycemic events despite optimized insulin therapy. To improve C-peptide levels in patients with both T1 and T2 Diabetes, numerous clinical trials have explored the efficacy of mesenchymal stem cells (MSCs), both as supporting cells to protect existing β cells, and as source for newly generated β cells. Transplantation of MSCs is found to be effective for T2D patients, but its efficacy in T1D is controversial, as the ability of MSCs to differentiate into functional β cells in vitro is poor, and transdifferentiation in vivo does not seem to occur. Instead, to address limitations related to supply, human embryonic stem cell (hESC)-derived β cells are being explored as surrogates for cadaveric islets. Transplantation of allogeneic hESC-derived insulin-producing organoids has recently entered Phase I and Phase II clinical trials. Stem cell replacement therapies overcome the barrier of finite availability, but they still face immune rejection. Immune protective strategies, including coupling hESC-derived insulin-producing organoids with macroencapsulation devices and microencapsulation technologies, are being tested to balance the necessity of immune protection with the need for vascularization. Here, we compare the diverse human stem cell approaches and outcomes of recently completed and ongoing clinical trials, and discuss innovative strategies developed to overcome the most significant challenges remaining for transplanting stem cell-derived β cells.