A Review of Autologous Islet Transplantation

Phase-changing citrate macromolecule combats oxidative pancreatic islet damage, enables islet engraftment and function in the omentum

Clinical outcomes for total-pancreatectomy followed by intraportal islet autotransplantation (TP-IAT) to treat chronic pancreatitis (CP) are suboptimal due to pancreas inflammation, oxidative stress during islet isolation, and harsh engraftment conditions in the liver's vasculature. We describe a thermoresponsive, antioxidant macromolecule poly(polyethylene glycol citrate-co-N-isopropylacrylamide) (PPCN) to protect islet redox status and function and to enable extrahepatic omentum islet engraftment. PPCN solution transitions from a liquid to a hydrogel at body temperature. Islets entrapped in PPCN and exposed to oxidative stress remain functional and support long-term euglycemia, in contrast to islets entrapped in a plasma-thrombin biologic scaffold. In the nonhuman primate (NHP) omentum, PPCN is well-tolerated and mostly resorbed without fibrosis at 3 months after implantation. In NHPs, autologous omentum islet transplantation using PPCN restores normoglycemia with minimal exogenous insulin requirements for >100 days. This preclinical study supports TP-IAT with PPCN in patients with CP and highlights antioxidant properties as a mechanism for islet function preservation.

Total pancreatectomy with intraportal islet autotransplantation for pancreatic malignancies: a literature overview

INTRODUCTION

'Brittle Diabetes' (BD) is a life-threatening metabolic complication after total pancreatectomy (TP). More than 500 Intraportal islet autotransplantation (IAT) have been performed to prevent this complication, with almost 70% insulin independence after 3 years. Even when insulin independence was not achieved, IAT successfully prevented severe hypoglycemia. Currently, preliminary results for oncologic situations are promising, but their oncological outcomes are still a matter of debate.

AREAS COVERED

We performed a bibliographic research of the last 25 years of data. Articles published in English in peer-reviewed journals were retained. In France, auto- and allo-islet transplantation was recently recognized as a valuable treatment for BD by the national health authority. While accepted for benign diseases, the risk of tumor spreading after IAT in oncologic situations is a source of concern.

EXPERT OPINION

Preliminary results of IAT in oncological situations are very encouraging. So far, there is no evidence of tumor dissemination. In our opinion, to overcome BD TP with IAT for resectable pancreatic malignancies in patients with a higher risk of postoperative pancreatic fistula and extended pancreatic cancers can be safely performed. Diagnosis of malignancy should not be considered as an exclusion criterion for IAT.

Portal Vein Thrombosis May Be More Strongly Associated With Islet Infusion Than Extreme Thrombocytosis After Total Pancreatectomy With Islet Autotransplantation

BACKGROUND

Total pancreatectomy with islet autotransplantation (TPIAT) involves pancreatectomy, splenectomy, and reinjection of the patient's pancreatic islets into the portal vein. This process triggers a local inflammatory reaction and increase in portal pressure, threatening islet survival and potentially causing portal vein thrombosis. Recent research has highlighted a high frequency of extreme thrombocytosis (platelets ≥1000 × 109/L) after TPIAT, but its cause and association with thrombotic risk remain unclear.

METHODS

This retrospective single-site study of a contemporary cohort of 409 pediatric and adult patients analyzed the frequency of thrombocytosis, risk factors for thrombosis, and antiplatelet and anticoagulation strategies.

RESULTS

Of 409 patients, 67% developed extreme thrombocytosis, peaking around postoperative day 16. Extreme thrombocytosis was significantly associated with infused islet volumes. Thromboembolic events occurred in 12.2% of patients, with portal vein thromboses occurring significantly earlier than peripheral thromboses. Portal vein thromboses were associated with infused islet volumes and portal pressures but not platelet counts or other measures. Most thromboembolic events (82.7%) occurred before the postoperative day of maximum platelet count. Only 4 of 27 (14.8%) of portal vein thromboses occurred at platelet counts ≥500 × 109/L. Perioperative heparin was given to all patients. Treatment of reactive thrombocytosis using aspirin in adults and hydroxyurea in children was not associated with significantly decreased thromboembolic risk.

CONCLUSIONS

These results suggest that post-TPIAT thrombocytosis and portal vein thromboses may be linked to the islet infusion inflammation, not directly to each other, and further reducing this inflammation may reduce thrombosis and thrombocytosis frequencies simultaneously.

Total Pancreatectomy with Autologous Islet Cell Transplantation-The Current Indications

Total pancreatectomy is a major complex surgical procedure involving removal of the whole pancreatic parenchyma and duodenum. It leads to lifelong pancreatic exocrine and endocrine insufficiency. The control of surgery-induced diabetes (type 3) requires insulin therapy. Total pancreatectomy with autologous islet transplantation (TPAIT) is performed in order to prevent postoperative diabetes and its serious complications. It is very important whether it is safe and beneficial for patients in terms of postoperative morbidity and mortality, and long-term results including quality of life. Small duct painful chronic pancreatitis (CP) is a primary indication for TPAIT, but currently the indications for this procedure have been extended. They also include hereditary/genetic pancreatitis (HGP), as well as less frequent indications such as benign/borderline pancreatic tumors (intraductal papillary neoplasms, neuroendocrine neoplasms) and “high-risk pancreatic stump”. The use of TPAIT in malignant pancreatic and peripancreatic neoplasms has been reported in the worldwide literature but currently is not a standard but rather a controversial management in these patients. In this review, history, technique, indications, and contraindications, as well as short-term and long-term results of TPAIT, including pediatric patients, are described.

Short- and long-term surgical outcomes of total pancreatectomy with islet autotransplantation: A comparative analysis of surgical technique and intraoperative heparin dosing to optimize outcomes

BACKGROUND

Total pancreatectomy with islet autotransplantation (TP-IAT) is an uncommon surgical procedure with unique perioperative management. We evaluated the short- and long-term morbidity and mortality of TP-IAT to optimize surgical technique and heparin dosing during islet autotransplantation.

METHODS

Eighty patients with chronic pancreatitis undergoing TP-IAT were reviewed. Primary outcome was to evaluate morbidity and mortality based on operative technique: classic (resection of antrum) vs pylorus-preserving. Secondary outcome was to evaluate the effect of heparin dosing (<60 vs ≥ 60 units/kg) during islet autotransplantation on postoperative hemorrhage and portal vein thrombosis (PVT) rates.

RESULTS

There was no 90-day mortality, and median length of stay was 9 days. All patients underwent an open operation with 53 (66%) pylorus-preserving resections. The 30-day morbidity rate was 39%, with no difference between operative technique (p = 0.82). The median dose was different for each heparin group (<60: 52 units/kg vs ≥ 60: 66 units/kg, p < 0.0001). No difference was observed in postoperative hemorrhage rates between heparin groups (<60: 9% vs ≥ 60: 9%, p = 0.97), with no known incidence of PVT. Median follow-up was 36 months (IQR, 14-71). Morbidity >30 days after TP-IAT was 43% with a higher rate in the pylorus-preserving group (55% vs 15%, p < 0.0001), mainly attributed to marginal ulcer formation (15% vs 0%, p = 0.03).

CONCLUSIONS

A classic TP-IAT technique should be universally adopted to achieve optimal outcomes, particularly to prevent the formation of marginal ulcers. When considering PVT versus postoperative hemorrhage risk, a lower heparin dose nearing 50 units/kg is optimal. These findings highlight potential areas for future improvement.

Islet Harvest in Carbon Monoxide-Saturated Medium for Chronic Pancreatitis Patients Undergoing Islet Autotransplantation

Stresses encountered during human islet isolation lead to unavoidable β-cell death after transplantation. This reduces the chance of insulin independence in chronic pancreatitis patients undergoing total pancreatectomy and islet autotransplantation. We tested whether harvesting islets in carbon monoxide-saturated solutions is safe and can enhance islet survival and insulin independence after total pancreatectomy and islet autotransplantation. Chronic pancreatitis patients who consented to the study were randomized into carbon monoxide (islets harvested in a carbon monoxide-saturated medium) or control (islets harvested in a normal medium) groups. Islet yield, viability, oxygen consumption rate, β-cell death (measured by unmethylated insulin DNA), and serum cytokine levels were measured during the peri-transplantation period. Adverse events, metabolic phenotypes, and islet function were measured prior and at 6 months post-transplantation. No adverse events directly related to the infusion of carbon monoxide islets were observed. Carbon monoxide islets showed significantly higher viability before transplantation. Subjects receiving carbon monoxide islets had less β-cell death, decreased CCL23, and increased CXCL12 levels at 1 or 3 days post transplantation compared with controls. Three in 10 (30%) of the carbon monoxide subjects and none of the control subjects were insulin independent. This pilot trial showed for the first time that harvesting human islets in carbon monoxide-saturated solutions is safe for total pancreatectomy and islet autotransplantation patients.

Portal Vein Thrombosis After Total Pancreatectomy and Islet Autotransplant: Prophylaxis and Graft Impact

OBJECTIVES

To determine the rate of portal vein thrombosis (PVT) based on pharmacologic prophylaxis protocol and the impact of PVT on islet graft function after total pancreatectomy with islet autotransplantation (TPIAT).

METHODS

We compared the incidence of PVT, postsurgical bleeding, and thrombotic complications in patients undergoing TPIAT between 2001 and 2018 at the University of Minnesota who received either unfractionated heparin (UFH) or enoxaparin for postoperative PVT prophylaxis. Six-month and 1-year graft function was compared between patients who developed PVT and those who did not.

RESULTS

Twelve patients (6.6%) developed a PVT, which resolved by 6 months after TPIAT in 10 patients. There was no statistically significant difference in PVT rate between patients who received UFH or enoxaparin for prophylaxis (P = 0.54). Patients who received enoxaparin developed other thrombotic complications more often (6% vs 0%, P = 0.02). Islet graft function did not differ in patients who developed PVT versus those who did not.

CONCLUSIONS

There was no difference between enoxaparin or UFH prophylaxis in preventing PVT, but there may be a higher incidence of other thrombotic complications with enoxaparin. In the setting of routine screening and anticoagulation therapy, PVT is a self-limited process.