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Background Using standard density gradient (SDG) ranges for human islet purification frequently results in islet loss and transplantation of lower islet mass. Measuring the densities of islet and acinar tissue beforehand to customize the gradient range for the actual COBE 2991 cell processor (COBE) purification is likely to maximize the recovery of islets. We developed an analytical test gradient system (ATGS) for predicting pancreatic tissue densities before COBE purification to minimize islet loss during purification. Methods Human islets were isolated from deceased donor (n=30) and chronic pancreatitis pancreata (n=30). Pancreatic tissue densities were measured before purification by the ATGS, and the density gradient range for islet purification in a COBE was customized based on density profiles determined by the ATGS. The efficiency of custom density gradients (CDGs) to recover high islet yield was compared with predefined SDGs. Results Pancreatic tissue densities from autografts were significantly higher than in allograft preparations. In allograft purifications, a higher proportion of islets were recovered using ATGS-guided CDGs (85.9%±18.0%) compared with the SDG method (69.2%±27.0%; P=0.048). Acinar contamination at 60%, 70%, and 80% cumulative islet yield for allografts was significantly lower in the CDG group. In autograft purifications, more islets were recovered with CDGs (81.9%±28.0%) than SDGs (55.8%±22.8%; P=0.03). CDGs effectively reduced islet loss by minimizing islet sedimentation in the COBE bag. Conclusions Using ATGS-guided CDGs maximizes the islet recovery for successful transplantations by reducing acinar contamination in allograft preparations and by reducing sedimentation of islets in the COBE bag in autograft preparations.

Recently, we demonstrated that islet transplantation from non-heart-beating donors (NHBDs) using the Kyoto islet isolation method (KIIM) successfully reversed patients' diabetes state. In this study, we evaluated the effects of donor- and isolation-related variables on islet isolation results from NHBDs by KIIM. Twenty-one islet preparations from the pancreata of NHBDs were isolated by KIIM. Islet preparations that met transplantation criteria and achieved improved patient diabetes control after transplantation were defined as successful isolations. Potential risk factors deemed to affect islet isolation results, such as age, gender, body mass index, hospital stay, donors' blood biochemical tests, a modified pancreata procurement method, and isolation and purification procedure-related variables, were analyzed. Seventeen out of 21 islet isolations (81%) were successful isolations. Postpurification islet yield was 447,639 ± 39,902 islet equivalents (IE) in the successful isolation group and 108,007 ± 31,532 IE in the failure group. Donor age was significantly younger in the success group (41.9 ± 4.0 years old in the success group vs. 57.5 ± 2.2 years old in the failure group, p = 0.003). Chronic pancreatitis significantly decreased islet yields (p = 0.006). Phase I time was significantly shorter (p = 0.010) and undigested tissue volume was significantly smaller (p = 0.020) in the success group. Purity was in positive correlation to postpurification islet yield, while donor age was in reverse correlation to postpurification islet yield. KIIM enables us to perform islet transplantation from NHBDs; however, the decision to use pancreata from older donors or those with chronic pancreatitis requires careful consideration.

We performed the world's first successful living donor islet transplantation for unstable diabetes. A total of 408,114 islet equivalents were isolated from half a living pancreas and transplanted immediately to the recipient who was a 27-year-old female. The donor was a 56-year-old female in good health, mother of the recipient. The islets functioned immediately, and the recipient was weaned completely from insulin on the 22nd posttransplant day, and has maintained excellent glycemic control since. The donor was discharged on the 18th postoperative day with normal oral glucose tolerance test and without complications. Living donor islet transplantation could cure one insulin-dependent diabetes mellitus patients with a single donor. There are some advantages in the living donor islet transplantation: (a) living donor can alleviate the issue of donor shortage; (b) highly potent islets can be isolated from a living donor; and (c) the recipient can be treated with immunosuppressant and controlled blood glucose level tightly prior to the transplantation. These are important factors in overcoming the obstacles limiting islet transplantation. We believe that the living donor islet transplantation may become an additional option in treating insulin-dependent diabetes.

We investigated glycemic stability and insulin requirement 1 month after a single transplantation of the islets from non-heart-beating donors or a living donor. Overall blood glucose levels decreased immediately after transplantation. The M-value and mean amplitude of glycemic excursions (MAGE) decreased significantly from 53.0 (range, 8.9-91.0) to 4.2 (0.6-8.8, P0.05) and from 8.5 mM (4.8-11.7) to 3.3 mM (2.0-4.5, P0.05), respectively. The values after transplantation were lower than the first quartile of 102 type 2 diabetic control patients. The estimated HbA1c level decreased significantly from 7.9% (5.7-10.9) to 5.4% (4.7-5.9, P0.05). The supplement of basal insulin decreased 43% from 0.31 units/kg/day (0.16-0.37) to 0.18 units/kg/day (0-0.22, P0.05), while that of stimulated insulin did not decrease significantly, from 0.28 units/kg/day (0.13-0.51) to 0.21 units/kg/day (0-0.41). Thus, only one islet transplantation can be sufficient to attain metabolic stability, probably by effective supply of basal insulin secretion, sufficient to avoid life-threatening severe hypoglycemia and prevent or delay the progress of secondary complications of diabetes by decreasing the HbA1c level.

BACKGROUND Current success of islet transplantation has led to donor shortage and the need for marginal donor utilization to alleviate this shortage. The goal of this study was to improve the efficacy of islet transplantation using nonheartbeating donors (NHBDs). METHODS First, we used porcine pancreata for the implementation of several strategies and applied to human pancreata. These strategies included ductal injection with trypsin inhibitor for protection of pancreatic ducts, ET-Kyoto solution for pancreas preservation, and Iodixanol for islet purification. RESULTS These strategies significantly improved both porcine and human islet isolation efficacy. Average 399,469+/-36,411 IE human islets were obtained from NHBDs (n=13). All islet preparations met transplantation criteria and 11 out of 13 cases (85%) were transplanted into six type 1 diabetic patients for the first time in Japan. All islets started to secrete insulin and all patients showed better blood glucose control without hypoglycemic loss of consciousness. The average HbA1c levels of the six recipients significantly improved from 7.5+/-0.4% at transplant to 5.1+/-0.2% currently (P

BACKGROUND Recent advances in pancreatic islet transplantation (PIT) have contributed significantly to the treatment of patients with type 1 diabetes. The specific aim of this study was to develop an effective technique for the procurement of pancreas for PIT from nonheart-beating-donor (NHBDs). METHODS Between January 2004 and August 2004, eight human pancreata were procured and processed for isolation of islets at a cell processing center. After confirmation of brain death status, a double balloon catheter was inserted to prevent warm ischemic damage to the donor pancreas by using an in situ regional organ cooling system that was originally developed for procurement of kidneys. The catheter position of the cooling system was modified specifically for the pancreas and kidney. Furthermore, we worked in cooperation with a kidney procurement team to protect the pancreas during kidney procurement. RESULTS Warm ischemic time could be controlled with the modified in situ regional cooling system at 3.0 +/- 0.8 min (mean +/- SE). The operations for procurement of the kidneys and pancreata lasted 45.6 +/- 3.6 min and 10.6 +/- 1.8 min, respectively. Islet yield per isolation was 444,426 +/- 35,172 IE (islet equivalent). All eight cases met the criteria for PIT based on the Edmonton protocol. CONCLUSION We developed a novel procurement technique in cooperation with our kidney procurement team. This protocol for the procurement of pancreas and kidney from a NHBD enabled us to transplant islets into a type 1 diabetic patient and kidney into a renal failure patient.

Islet allotransplantation can achieve insulin independence in patients with type I diabetes. Recent reports show that the two-layer method (TLM), which employs oxygenated perfluorochemical (PFC) and UW solution, is superior to simple cold storage in UW for pancreas preservation in islet transplantation. However, UW solution has several disadvantages, including the inhibition of Liberase activity. In this study, we investigated the features of a new solution, designated M-Kyoto solution. M-Kyoto solution contains trehalose and ulinastatin as distinct components. Trehalose has a cytoprotective effect against stress, and ulinastatin inhibits trypsin. In porcine islet isolation, islet yield was significantly higher in the M-Kyoto/PFC group compared with the UW/PFC group. There was no significant difference in ATP content in the pancreas between the two groups, suggesting that different islet yields are not due to their differences as energy sources. Compared with UW solution, M-Kyoto solution significantly inhibited trypsin activity in the digestion step; moreover, M-Kyoto solution inhibited collagenase digestion less than UW solution. In conclusion, the advantages of M-Kyoto solution are trypsin inhibition and less collagenase inhibition. Based on these data, we now use M-Kyoto solution for clinical islet transplantation from nonheart-beating donor pancreata.

Pancreatic islet transplantation is a curable treatment for type 1 diabetes and has been put into practice in various countries. In this study, we analyzed the pharmacokinetic characteristics of sirolimus and tacrolimus in six Japanese patients with pancreatic islet transplants immediately after surgery, and monitored efficacy and toxicity. The patients were treated with immunosuppressive therapy based on the Edmonton protocol, that is, sirolimus and low-dose tacrolimus. Pharmacokinetic analyses were performed using the nonlinear mixed-effects modeling program NONMEM. Large inter- and intra-individual variability was observed in the pharmacokinetics of sirolimus and tacrolimus. A model with increased apparent clearance in the postoperative period explained well the intra-individual variability in the pharmacokinetics of both drugs. The most frequent drug-induced toxicity was a decrease in the white blood cell count, and two of six patients required the administration of granulocyte colony-stimulating factor. Clinical laboratory tests immediately before the transplantation and cytochrome P450 3A5 genotype were not related to the high blood concentrations of sirolimus after the loading dose. From these results, the apparent clearance of sirolimus and tacrolimus might temporally decline immediately after pancreatic islet transplantation. A high trough concentration of sirolimus might increase the risk of hematological toxicy, and adjustment of the dosage for immunosuppressive treatment will be necessary in Japanese patients.

Although application of the Edmonton protocol has markedly improved outcomes for pancreatic islet transplantation, the insulin independence rate after islet transplantation from one donor pancreas has proven to remain low. During the isolation process and subsequent clinical transplantation, islets are subjected to severe adverse conditions that impair survival and ultimately contribute to graft failure. Pancreas preservation with the two-layer method (TLM) has proven to improve transplant results by protecting isolated islets against apoptosis through the mitochondrial pathway. However, pancreas storage with TLM cannot protect against activation of c-Jun NH2-terminal kinase (JNK) in isolated islets. This study investigated whether delivery of a JNK inhibitory peptide (JNKI) via the protein transduction system can prevent apoptosis of islet cells immediately after isolation. For efficient delivery of the (JNKI into isolated islets, we synthesized JNKI as a C-terminal fusion peptide with the 11-arginine protein transduction domain (11R-JNKI). 11R efficiently delivered the JNKI into isolated islets and 11R-JNKI prevented islet apoptosis immediately after isolation and improved islet graft function. These findings suggest that peptide drugs could be useful for the prevention of the impairment of islet cells and lead to improvement in the outcomes for pancreatic islet transplantation.

Evaluation of engraftment is important to assess the success of islet transplantation. Recently we developed secretory unit of islet transplant objects (SUITO) index for simple evaluation of engraftment. Assuming that normal subjects aged40 years have 100% pancreatic beta-cell function, SUITO index was calculated by the formula: 1500 x fasting C-peptide immunoreactivity [ng/dL]/(fasting blood glucose [mg/dL] - 63). In this study, we compared the efficacy of islet transplantation from cadaveric and living donors using the SUITO index.We performed eight islet transplantations with non-heart-beating donors (NHBDs) into five patients. Two patients received fresh islets once, one patient received fresh islets twice, one patient received cultured islets once, and one patient received cultured islets twice plus fresh islets once. In addition, one patient received fresh islets from a living donor. We calculated the SUITO index from postoperative days 3 to 30 for each case.Mean SUITO index after one fresh islet transplant was 11.7 +/- 1.0, after two fresh islet transplants was 28.5 +/- 3.4, after one cultured islet transplant was 2.1 +/- 0.4, after two cultured islet transplant was 12.1 +/- 1.9, and after two cultured islet transplant plus one fresh islet transplant was 26.7 +/- 1.7. The mean SUITO index after single living donor islet transplant was 40.7 +/- 2.6, which was significantly higher compared with all other groups. Insulin independence was obtained when the SUITO index was26, which might reflect that 26% beta-cell mass was required for insulin independence.SUITO index is useful to evaluate islet engraftment and to predict the possibility of insulin independence.

Background Current success in islet transplantation will lead to a donor shortage. Living donor islet transplantation could be an alternative approach to expand the potential donor pool. In this study we describe the first successful living donor islet transplantation for unstable diabetes, performed at Kyoto University Hospital on January 19, 2005. Methods The donor was a healthy 56-year-old woman and mother of the recipient. The recipient was a 27-year-old woman with insulin-dependent diabetes since the age of 15 years. She experienced frequent hypoglycemic unawareness episodes. Her blood glucose concentration was difficult to control and C-peptide level was negative after glucagon stimulation. She needed an average 28 of units of insulin per day. The donor underwent a distal pancreatectomy and islets were isolated from the resected pancreas graft. The total islet yield was 408,114 islet equivalents and isolated islets were immediately transplanted into the recipient’s liver. Results After transplant, the blood glucose level of the recipient was tightly controlled without hypoglycemic episodes. She was discharged on day 37 with a normal oral glucose tolerance test (OGTT). The recipient remained insulin-independent for >3 months, since day 22 posttransplant. The donor’s postoperative clinical course was uneventful. She was discharged on postoperative day 18 and returned to her job within 1 month. Conclusions We report the first successful living donor islet transplantation for the treatment of unstable diabetes. We believe that living donor islet transplantation may become an option in the treatment of insulin-dependent diabetes.

Background The specific aim of this study was to develop an effective technique for pancreas procurement for islet transplantation from a non–heart-beating donor (NHBD). Methods Between January 2004 and November 2004, 11 human pancreata were procured and processed for islet isolation at a cell processing center. After confirmation of brain-death status, a double-balloon catheter was inserted to prevent warm ischemic damage to the donor pancreas by using an in situ regional organ cooling system that was originally developed for kidney procurement. Results Warm ischemic time was controlled with the modified in situ regional cooling system at 6.0 ± 0.9 minutes (mean ± SE). The operations for procurement of the kidneys and pancreata lasted 48.1 ± 3.6 minutes and 9.9 ± 4.8 minutes, respectively. The islet yield per isolation was 396,767 ± 142,842 IE (islet equivalents). Ten of the 11 cases met the criteria for pancreatic islet transplantation based on the Edmonton protocol. Conclusions We developed a novel procurement technique in cooperation with our kidney procurement team. This protocol for the procurement of pancreas and kidney from an NHBD enabled us to transplant islets into a type 1 diabetic patient and kidney into a renal failure patient.

Islet autotransplantation (IAT) is used to preserve as much insulin-secretory capacity as possible in patients undergoing total pancreatectomy for painful chronic pancreatitis. The enzyme used to dissociate the pancreas is a critical determinant of islet yield, which is correlated with posttransplant function. Here, we present our experience with IAT procedures to compare islet product data using the new enzyme SERVA/Nordmark (SN group; n = 46) with the standard enzyme Liberase-HI (LH group; n = 40). Total islet yields (mean +/- standard deviation; 216,417 +/- 79,278 islet equivalent [IEQ] in the LH group; 227,958 +/- 58,544 IEQ in the SN group; p = 0.67) were similar. However, the percentage of embedded islets is higher in the SN group compared to the LH group. Significant differences were found in pancreas digestion time, dilution time, and digested pancreas weight between the two groups. Multivariate linear regression analysis showed the two groups differed in portal venous pressure changes. The incidence of graft function and insulin independence was not different between the two groups. The SN and LH enzymes are associated with similar outcomes for IAT. Further optimization of the collagenase/neutral protease ratio is necessary to reduce the number of embedded islets obtained when using the SN enzyme.

Background. Islet transplantation is gradually gaining acceptance for the treatment of type 1 diabetes mellitus. One of the unknown questions is alcohol intake; we have prohibited alcohol intake after islet transplantation although there is no solid evidence to support this. Materials and Methods. In this study, we employed a mouse model to determine the effect of oral ethanol intake on transplanted islets. Either 500 or 150 islets were infused selectively into the right liver lobe of chemically induced diabetic mice. After transplantation, mice were orally administered either water (as a control) or various concentrations of ethanol for 14 consecutive days occasionally (once per day) or continuously (all intake was alcohol). Blood glucose levels were monitored and oral glucose tolerance tests (OGTT) performed. Results. After 500 islets had been transplanted, all mice were cured from diabetes, but the continuous alcohol intake group showed significantly prolonged time to diabetes reversal and significantly lower glucose clearance rates by OGTT compared with the control group. After 150 islet transplantations, the diabetes cure rate in the continuous alcohol intake group was significantly lower than the control group (continuous alcohol vs control: 3/8 vs 11/12, P

Background. Islet transplantation has become an option for the treatment of insulin-dependent diabetes mellitus and is usually performed using brain-dead heartbeating donors. However, we have very limited number of such donors in Japan; therefore, it is not allowed to perform islet transplantation with brain-dead donors. In order to perform islet transplantation in Japan, we need to seek new donor resources. Methods. We performed the first successful living-donor islet transplantation. In this case, the recipient had brittle diabetes with hypoglycemic unawareness. The donor was deemed qualified after undergoing both metabolic and preoperative assessments. Distal pancreatectomy was performed using open laparotomy and more than 400,000 islets were isolated and transplanted immediately. Results. The recipient has been insulin independent posttransplant with positive C-peptide for more than one year. She no longer suffers from hypoglycemic unawareness and displayed a substantial improvement in hemoglobulin (Hb) A 1C . The donor's clinical course was uneventful, which allowed her to return to her job within one month. She maintained normal fasting C-peptide and HbA 1C levels during follow-up period. Conclusion. In our first case of living donor islet transplantation, both the donor and the recipient have been maintaining excellent glycemic control with no untreatable complications for more than one year.

Intraportal site is the standard for grafting in clinical islet transplantation. In the mouse model, the whole liver has been used as the grafting site to mimic clinical islet transplantation. However, this model lacks the potency to directly assess the contribution of the islet graft to diabetes control. Only demonstrating the immediate recurrence of diabetes in a surviving recipient after the removal of the islet graft can validate this assessment. In this study, we develop a mouse model of intraportal islet transplantation equipped with the potency of this assessment by injecting islets selectively into the right hepatic lobe under temporal clamp of the left portal vein. The mouse of this model survives after the right hepatectomy by which the islet graft is removed. This model can be applied to investigate both the specific graft-recipient interaction in the liver and the islet graft contribution to the control of diabetes.

We evaluated islet transplantation from non-heart beating donors (NHBDs) with our Kyoto Islet Isolation Method. All patients had positive C-peptide after transplantation. The average HbA(1C) levels of the five recipients significantly improved from 7.8 +/- 0.4% at transplant to 5.2 +/- 0.2% currently (p < 0.01). Three patients with no or a single autoantibody became insulin independent while the other two patients with double autoantibodies reduced their insulin requirement but did not become insulin independent. C-peptide in patients who became insulin-independent gradually increased after each transplantation whereas C-peptide in patients who did not become insulin-independent from 3 months after the first transplantation to the next transplantation dramatically decreased. The beta-score of the three patients who became insulin independent was the best of eight. In conclusion, our method makes it feasible to use NHBDs for islet transplant into type 1 diabetic patients efficiently.

Pancreatic islet transplantation is one of the options for treating diabetes and has been shown to improve the quality of life of severe diabetic patients. Since the Edmonton protocol was announced, islet transplantation have advanced considerably, including islet after kidney transplantation, utilisation of non-heart-beating donors, single-donor islet transplantation and living-donor islet transplantation. These advances were based on revised immunosuppression protocols, improved pancreas procurement and islet isolation methods, and enhanced islet engraftment. Further improvements are necessary to make islet transplantation a routine clinical treatment. To synergise efforts towards a cure for type 1 diabetes, a Diabetes Research Institute (DRI) Federation is currently being established to include leading diabetes research centres worldwide, including DRIs in Miami, Edmonton and Kyoto among others.

The availability of pancreata for clinical cadaveric islet transplantation is restricted to non-heart-beating donors (NHBDs) in Japan. This forced us to modify the current standard islet isolation protocol that was made up for brain-dead donors and make it suitable for NHBDs. The Kyoto islet isolation method is the one with induction of several steps based on the ideas both already reported literally and invented originally by ourselves. Using this islet isolation method, we isolated islets from 13 human pancreata of NHBDs and transplanted 11 preparations to six type-1 diabetic patients. The rate to meet release criteria of Edmonton protocol was 84.6%. Establishment of this method allowed us to begin a clinical islet transplantation program in Japan and to continue to perform the preparation of islets from NHBDs with high rate to meet the release criteria of the Edmonton protocol.

Achieving good islet isolation is one of the most important factors for successful islet transplantation. Porcine pancreas is suitable for islet isolation research due to its anatomical and physiological similarities to human pancreas. In this study, we evaluated a new porcine islet isolation method designed to maximize islet yield and compared it with our previous open pan method and the standard method using a Ricordi chamber (Ricordi method). We performed 15 porcine islet isolations, five each with the new method, the open pan method, and the Ricordi method. The new method features several important improvements. Pancreata remain uncut and are kept intact during collagenase intraductal injection, a large filtration chamber to handle whole pancreata, low concentration of collagenase (Liberase™ HI) for digestion, and large plastic containers for large-scale islet purification. All isolated islets were assessed for yield, purity, viability and in vitro function. Islets isolated with this new method were transplanted under the kidney capsules of SCID mice with chemically induced diabetes for in vivo functional assessment (n = 8). With the new method, we obtained on average more than 1,000,000 islet equivalents (IE) (1,236,266 ± 213,486 IE) (mean ± SE) before purification and 800,000 IE (879,815 ± 222,729 IE) after purification from one adult pig. Islet yield per pancreas was significantly higher compared with our previous open pan method (30,666 ± 11,532 IE, p < 0.01) and the Ricordi method (317,073 ± 86,093 IE, p < 0.05). All mice, transplanted with 1000 islets from the new method, returned to normoglycemia within 4 days after transplantation. Our new method makes it possible to obtain extremely high porcine islet yield with good function. It should produce useful information for human islet isolation and transplantation, and might be applied to single donor clinical xenogeneic transplantation.

Aims. It is important to have clinically relevant large animal models, especially nonhuman primates, to improve the efficacy of islet isolation and transplantation prior to clinical trials. The aim of this study was to improve the efficacy of islet isolation by analyzing large-scale nonhuman primate islet isolations. Methods. Sixty-one islet isolations were evaluated using nonhuman primates. An automated isolation method was scaled down for islet isolation. Islet yields of prepurification, postpurification, and postculture, purity of islets, viability of islets, and functionality with glucose stimulation test were assessed. Initially, we analyzed relationships between endpoints then analyzed additional factors for successful islet isolation. Those factors included donor characteristics, the two-layer method (TLM) of pancreas preservation, trypsin inhibition during digestion, and digestion and collection time. Results. Prepurification islet yields were strongly correlated with postpurification yields and postculture yields. It weakly but significantly correlated with purity, viability, and functionality. The average prepurification yield was 16,267 IE/g with each case divided into either above-average (high-yield group) or below-average groups (low-yield group). In 8 cases, TLM and trypsin inhibition were used and all cases belonged to the high-yield group. There were no significant differences between high- and low-yield groups in terms of donor age, body weight, pancreas weight, and cold ischemic time. The high-yield group had significantly longer digestion times and shorter collection times. Conclusions. TLM, trypsin inhibition, complete digestion, and quick collections were key for successful islet isolation. Analysis of nonhuman primate islet isolation techniques provided useful information, which should help to improve clinical islet transplantation.

Expansion of pancreatic islet cell populations, especially the beta cells, using a currently available ex vivo gene transfer technology is important to develop cell therapies to treat Type I diabetes. In this study, we evaluated adenovirus mediated gene transfer efficiency in primarily isolated mouse islet cells in two types of culture conditions: freshly isolated suspended islets and cultured islets with monolayer formation. A recombinant replication deficient adenovirus vector encoding a green fluorescence protein (GFP) cDNA, Ad/ CMV-GFP, was used in the present transduction experiments. Rat 804G derived extracellular matrix (804G-ECM) and 3-isobutyl-1-methylxanthine (IBMX) were used to facilitate monolayer formation of the isolated mouse pancreatic islets. Suspended islets were transfected with Ad/CMV-GFP at more than 95% efficiency. However, analysis of immunohistochemical stains for insulin and glucagon in thin sliced sections of the islets revealed that GFP expression was localized just in the outer cells of the islets, almost all of which were glucagon positive alpha-cells. The beta-cells existing at the inner area of the suspended islets were GFP negative. In contrast, under the condition of the islets in monolayer formation cultures, all of the islet cells including the beta-cells were efficiently infected with Ad/CMV-GFP. To achieve an efficient adenoviral gene transfer to the pancreatic beta-cells, monolayer formation of the islets is critical. Such culture conditions were facilitated by combining 804G-ECM with IBMX.