Evaluation of intrathymic islet transplantation in the prediabetic period.

BACKGROUND. Beta-cell destruction in type I diabetes mellitus results from a chronic autoimmune process. Exposure of thymic T cells to islet antigens during the prehyperglycemic phase of diabetes may alter the likelihood of autoimmune damage to beta cells in the native pancreas. Thus we evaluated whether prophylactic major histocompatibility complex (MHC)-incompatible intrathymic islet allografts could prevent hyperglycemia and native pancreatic beta-cell destruction. METHODS. At 4 to 6 weeks of age, diabetes-prone BioBreeding rats received intrathymic injection of 1500 to 2000 noncultured MHC-incompatible Lewis islets. No immunosuppression was administered. Age-matched littermates underwent intrathymic injection of saline solution. RESULTS. None of 13 BioBreeding rat recipients of prophylactic intrathymic Lewis islet allografts became hyperglycemic versus 13 of 13 control rats (p less than 0.001). The age at onset of diabetes in the control group ranged from 77 to 104 days (mean, 86 days). Normoglycemia in recipients of intrathymic islet allografts persisted for greater than 8 months after transplantation, and thymectomy (graft removal) did not precipitate hyperglycemia. CONCLUSIONS. Prophylactic intrathymic MHC-incompatible islet allografts effectively prevent hyperglycemia and native beta-cell destruction in an animal model of autoimmune diabetes. Rejection and autoimmune destruction of intrathymic MHC-incompatible islet allografts were not seen after transplantation in the prediabetic (prehyperglycemic) period. Intrathymic islet allografts at an early age (before puberty) preserve native beta-cell function and may prevent or retard thymic atrophy.     

Autologous islet transplantation to prevent diabetes after pancreatic resection.

BACKGROUND: Extensive pancreatic resection for small-duct chronic pancreatitis is often required for pain relief, but the risk of diabetes is a major deterrent. OBJECTIVE: Incidence of pain relief, prevention of diabetes, and identification of factors predictive of success were the goals in this series of 48 patients who underwent pancreatectomy and islet autotransplantation for chronic pancreatitis. PATIENTS AND METHODS: Of the 48 patients, 43 underwent total or near-total (> 95%) pancreatectomy and 5 underwent partial pancreatectomy. The resected pancreas was dispersed by either old (n = 26) or new (n = 22) methods of collagenase digestion. Islets were injected into the portal vein of 46 of the 48 patients and under the kidney capsule in the remaining 2. Postoperative morbidity, mortality, pain relief, and need for exogenous insulin were determined, and actuarial probability of postoperative insulin independence was calculated based on several variables. RESULTS: One perioperative death occurred. Surgical complications occurred in 12 of the 48 patients (25%): of these, 3 had a total (n = 27); 8, a near-total (n = 16); and 1, a partial pancreatectomy (p = 0.02). Most of the 48 patients had a transient increase in portal venous pressure after islet infusion, but no serious sequelae developed. More than 80% of patients experienced significant pain relief after pancreatectomy. Of the 39 patients who underwent total or near-total pancreatectomy, 20 (51%) were initially insulin independent. Between 2 and 10 years after transplantation, 34% were insulin independent, with no grafts failing after 2 years. The main predictor of insulin independence was the number of islets transplanted (of 14 patients who received > 300,000 islets, 74% were insulin independent at > 2 years after transplantation). In turn, the number of islets recovered correlated with the degree of fibrosis (r = -0.52, p = 0.006) and the dispersion method (p = 0.005). CONCLUSION: Pancreatectomy can relieve intractable pain caused by chronic pancreatitis. Islet autotransplantation is safe and can prevent long-term diabetes in more than 33% of patients and should be an adjunct to any pancreatic resection. A given patient's probability of success can be predicted by the morphologic features of the pancreas.     

Prevention of vascular complications of diabetes by pancreatic islet transplantation.

Isolated pancreatic islets from Wistar-Lewis rats were transplanted into the liver of diabetic allogeneic recipients to assess ability to prevent diabetic renal and ophthalmic complications. At nine months, the diabetic animals without transplants showed significant increase in PAS-positive material in the renal glomerular mesangium and thickening of glomerular arterioles as compared with normal nondiabetic animals. New vessel formation was also significant in the retina and retinal capillary dilation. Animals in which diabetes had been corrected by early pancreatic islet transplantation were completely protected from these changes, showing no significant pathologic change when compared with normal animals.     

Transaminitis after pancreatic islet transplantation

BACKGROUND: An asymptomatic, self-limited transaminitis uniformly follows pancreatic islet transplantation (PIT) performed through portal vein (PV) infusion. The underlying cause and significance of this transaminitis is unclear. STUDY DESIGN: Records of all patients with insulin-dependent diabetes mellitus who had undergone PIT at our institution were reviewed. All PITs were performed in conjunction with a remote pancreatic islet isolation center and done through percutaneous transhepatic PV infusion. Alanine aminotransferase (ALT) levels, serum glucose concentrations, insulin requirements, and color-flow Doppler ultrasonography examinations of the right upper quadrant were assessed before and after PIT. RESULTS: Eleven patients have undergone a total of 26 PITs. An elevated ALT level occurred in all 11 patients (100%) after the first PIT, with the median post-PIT peak ALT level reaching 187 IU/L. Transaminitis was less frequent and less marked after the second PIT. A negative correlation between viability of the pancreatic islets transplanted (r = -0.44, p = 0.03) and a positive correlation between the ratio of maximum to initial PV pressure (r = 0.41, p = 0.04) were seen with the subsequent ALT peak. Color-flow Doppler ultrasonography examinations showed no occurrences of PV thrombosis or intrahepatic hematoma. Finally, the degree of transaminitis did not correlate with post-PIT insulin requirements, indicating that post-PIT transaminitis cannot be used to measure allograft rejection or function. CONCLUSIONS: Transaminitis after PIT is common and self-limited. Post-PIT transaminitis does not signal acute rejection or serious procedure-related complications such as PV thrombosis or intrahepatic hematoma.     

Experimental pancreatic islet transplantation.

Transplantation of isolated islets of Langerhans has been suggested as a treatment of certain forms of diabetes mellitus. Injection of 200-400 syngeneic pancreatic islets isolated by collagenase digestion into the pancreas or submandibular gland of diabetic rats rendered most of the hosts nearly normoglycaemic. Blood glucose determinations were monitored for 2 months after islet transplantation. Although intrapancreatic and intrasubmandibular implantation reduced hyperglycaemia and polyuria in these animals, consistent normal values were rarely achieved.     

Comparison of the metabolic control of diabetes achieved by whole pancreas transplantation and pancreatic islet transplantation in rats

To compare the long-term effectiveness of whole pancreas transplantation and pancreatic islet transplantation in controlling the metabolic disorders of alloxan diabetes, metabolic studies were performed monthly for 2 years in 4 groups of highly inbred rats: (1) NC-116 nondiabetic controls; (2) DC-273 untreated alloxan-diabetic controls; (3) PDT-182 rats that received syngeneic pancreaticoduodenal transplants shortly after induction of diabetes with alloxan; and (4) IT-92 rats that received an intraportal injection of at least 1500, but usually 2000, syngeneic pancreatic islets shortly after induction of diabetes with alloxan. Whole pancreas transplantation maintained strict metabolic control throughout the 2 years of study. In group PDT, hyperglycemia was abolished; plasma glucose concentration was maintained tightly within the normal range; markedly depressed plasma insulin levels were raised to above normal; glucose tolerance tests had insulin levels above normal and glucose levels that increased less and declined more rapidly than normal; and body weight gain and growth approached normal. In contrast, pancreatic islet transplantation failed to maintain precise metabolic control. In group IT, plasma glucose concentration initially fell to normal but then was elevated significantly above normal beginning with the 3rd posttransplant month; plasma insulin level declined progressively after the 6th posttransplant month; glucose tolerance tests had a diabetic glucose tolerance curve as a result of a markedly deficient plasma insulin response; and body weight gain and growth were significantly less than in group PDT. The results of these long-term metabolic studies may explain the effectiveness of whole pancreas transplantation and the ineffectiveness of pancreatic islet transplantation in preventing diabetic nephropathy.     

Historical review of pancreatic islet transplantation

This historical perspective attempts to document the origin and early work of islet tissue transplantation. In the final analysis, most of these early experiments were failures. However, the ideas were clearly appropriate and in place at a very early phase. The first islet tissue transplantation was done in 1893; that is 29 years prior to the Banting's and Best's discovery of insulin therapy. Most of our current active approaches have been tried in the past. As is the case in many areas in science, the problems were defined with ideas and solutions outlined long ago. Yet, the problems were not solvable because of inadequate technology. The insight behind these early experiments must be admired, knowing the limited knowledge that was available. Keeping this historical perspective in mind as we work through our technologic opportunities may be of assistance as we approach our goal of clinical islet transplantation.

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Resumen Este resumen histórico procura documentar el origen y los trabajos iniciales en el área del transplante de islotes de Langerhans. En general casi todas las investigaciones originales resultaron en fracasos. Sin embargo, las ideas de esta etapa inicial eran obviamente apropiadas. El primer transplante de tejido de islotes se realizó en 1893, veinte y nueve años previo al descubrimiento de la insulina por Banting y Best. Una gran mayoría de los métodos actuales fueron utilizados previamente, pero la solución a los problemas no era factible debido a las limitaciones tecnológicas. La visión demostrada en estas investigaciones iniciales merecen mucho mérito considerando las limitaciones durante esa época. Manteniendo en mente estas investigaciones originales, mientras trabajamos con adelantos tecnológicos modernos, nos ayudará a realizar la meta de la aplicación clínica del transplante de islotes de Langerhans.

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Résumé Cette rétrospective historique essaie de retracer les origines et les premières études sur la greffe d'îlots pancréatiques. En dernière analyse la plupart de ces premières tentatives ont échoué. Cependant les conceptions étaient justes et présentes très tôt. La première greife d'îlots a été pratiquée en 1893, 29 ans avant la découverte de l'insulinothérapie par Banting et Best. La majeure partie des approches utilisées de nos jours ont déjà été expérimentées dans le passé. Comme dans bien d'autres domaines de la science, il y a longtemps que les problèmes ont été définis et les concepts et solutions envisagés. Mais ces problèmes n'étaient pas solubles, faute de technologie appropriée. La perspicacité de ces expériences initiales est admirable, sachant le peu de connaissances disponibles à cette époque. Il peut être utile de garder à l'esprit cette perspective historique alors que nous approchons de notre objectif, la transplantation d'îlots chez l'homme.

     

Reversal of diabetes by pancreatic islet transplantation into a subcutaneous, neovascularized device

BACKGROUND: Transplantation of pancreatic islets for the treatment of type 1 diabetes allows for physiologic glycemic control and insulin-independence when sufficient islets are implanted via the portal vein into the liver. Intrahepatic islet implantation requires specific infrastructure and expertise, and risks inherent to the procedure include bleeding, thrombosis, and elevation of portal pressure. Additionally, the relatively higher drug metabolite concentrations in the liver may contribute to the delayed loss of graft function of recent clinical trials. Identification of alternative implantation sites using biocompatible devices may be of assistance improving graft outcome. A desirable bioartificial pancreas should be easy to implant, biopsy, and retrieve, while allowing for sustained graft function. The subcutaneous (SC) site may require a minimally invasive procedure performed under local anesthesia, but its use has been hampered so far by lack of early vascularization, induction of local inflammation, and mechanical stress on the graft. METHODS: Chemically diabetic rats received syngeneic islets into the liver or SC into a novel biocompatible device consisting of a cylindrical stainless-steel mesh. The device was implanted 40 days prior to islet transplantation to allow embedding by connective tissue and neovascularization. Reversal of diabetes and glycemic control was monitored after islet transplantation. RESULTS: Syngeneic islets transplanted into a SC, neovascularized device restored euglycemia and sustained function long-term. Removal of graft-bearing devices resulted in hyperglycemia. Explanted grafts showed preserved islets and intense vascular networks. CONCLUSIONS: Ease of implantation, biocompatibility, and ability to maintain long-term graft function support the potential of our implantable device for cellular-based reparative therapies.     

Whole pancreatic transplantation and islet transplantation. Experiment notes]

BACKGROUND: The results of pancreas transplantation have greatly improved in recent years. The path to further improvements goes through extensive experimental researches. METHODS: This study describes the effects of different procedures as hemodynamic asset and postoperative outcome. Twenty-nine swine underwent a total pancreatectomy, and were stratified into five groups. Group one (n = 5) served as control. Group two (n = 7) was autotransplanted. Group three (n = 6) and group four (n = 6) underwent allotransplantation; the first without immunosuppression and the second treated with cyclosporine and steroids. In group five (n = 5) Langerhans Islets transplantation was performed. RESULTS: Survival was different depending on which methodology was applied. The postoperative survival was 7 +/- 2 days in group one, 24 +/- 16 days in group two, 17 +/- 7 days in group three, 27 +/- 8 days in group four and 12 +/- 6 days in group five. CONCLUSIONS: The postoperative glucose control was normal in group two and group four while a severe diabetes appeared in group one (group 1 vs group 2: p < 0.05) and in group three during acute graft rejection after the 12th postoperative day (group 3 vs group 4: p < 0.05). Glycemia was slightly controlled in group five. The intraoperative hemodynamic status was evaluated at the time of pancreatectomy, harvesting, revascularization, and when surgery was over. Among the different parameters studied (mean arterial and pulmonary pressure, pulmonary wedge pressure, central venous pressure, cardiac output, oxygen extraction ratio, systemic vascular resistance, oxygen delivery and oxygen consumption), a statistically significant difference between group one and group five (p < 0.05) was observed.     

An evaluation of the activation of endogenous pancreatic enzymes during human islet isolations

Despite advances in human islet isolations, there remain inconsistencies in human islet yield and viability after collagenase digestion. It has been suggested that trypsin may contribute to the proteolysis of collagenase and the destruction of islet cells, or possibly exert indirect effects on the pancreas by activating other endogenous serine proenzymes. This study evaluated the effects of serine proteases on collagenase activity and profiled the kinetics of serine protease activity throughout human islet isolations with and without addition of Pefabloc, a serine protease inhibitor. Cadaveric pancreases were perfused in the presence (n = 12) and absence of Pefabloc (0.4 mmole; n = 8). Samples were collected before and throughout the digestion process and were assayed for trypsin, chymotrypsin, and elastase activity. A study of the enzyme kinetics of serine proteases throughout human islet isolations showed an increase in activity levels throughout the digestion period. There was a significant difference in the chymotrypsin (1342 +/- 503 and 384 +/- 71 units) and elastase (7.94 +/- 1.1 and 2.761 +/- 0.69 units) levels between the control and Pefabloc-supplemented isolations, respectively. There was no significance difference noted among the trypsin (88 +/- 27 and 54 +/- 18 units) levels between the control and Pefabloc-supplemented isolations, respectively. This demonstrates that serine proteases are effectively inhibited by Pefabloc during the islet isolation process. These data show that the presence of serine proteases may likely damage the islets upon prolonged digestion of the pancreatic tissue.     

Procurement of the human pancreas for pancreatic islet transplantation

BACKGROUND: The full potential of pancreatic islet transplantation (PIT) has not been realized because of the difficulties associated with islet isolation, particularly when associated with a remote islet isolation center. Herein, we describe the principles of pancreatic procurement for PIT, which have allowed us to achieve a successful pancreatic islet isolation rate 67% of the time when using a remote islet isolation center. METHODS: Between January 16, 2002 and June 30, 2003, 39 pancreata were procured and processed for PIT at a distant islet isolation center. All pancreata were procured by a single surgeon, and special attention was given to careful dissection of the pancreas, maintenance of arterial inflow and the pressure differential between arterial and venous systems during perfusion, rapid organ cooling, and rapid removal of the pancreas from the body. RESULTS: Twenty-six of 39 (67%) procured pancreata yielded more tha 5,000 islet equivalents (IEQ)/kg recipient weight and were transplanted. Median IEQs per isolation was 413,867, whereas median purity and viability were 65% and 100%, respectively. The median time for pancreatic excision was 34 minutes, whereas cold ischemia time was 6 hours and 40 minutes. DISCUSSION: The principles we have adopted for pancreatic procurement for PIT have resulted in a 67% islet isolation success rate despite the maintenance of more than 5,000 IEQ/kg and the use of a remote islet isolation center.     

Experimental vascularized segmentai pancreatic and islet transplantation in the baboon

The present study was undertaken to evaluate the effectiveness of cyclosporine (CYA) and total body irradiation (TBI) or total lymphoid irradiation (TLI) in suppressing segmental pancreatic allograft rejection in totally pancreatectomized outbred Chacma baboons. In addition, the study includes our preliminary results with subcapsular renal autotransplantation of dispersed autologous pancreas in the primate. CYA in doses of 25–50 mg/kg per day produced a slight but significant prolongation of graft survival. There was a wide variation of daily CYA serum trough levels exhibited between primates on the same daily oral dose, and there was no clear correlation between absolute CYA serum trough levels and rejection. Although heterotopic auto- or allotransplantation of the tail of the pancreas in the baboon was capable of maintaining normoglycemia in pancreatectomized baboons until rejection of the graft, glucose intolerance, reduced K-values, and hypoinsulinemia were consistent findings during glucose tolerance tests, suggesting transplantation of an insufficient islet cell mass. Animals that received 76 rad (TBI) remained normoglycemic between 14 and 36 days with a median of 22 days, which indicated a modest but significant prolongation of graft survival. Animals treated with TLI (600 rad) sustained graft function between 7 and 31 days with a median of 17 days. The optimal regimen of irradiation in terms of cumulative dose, dose per fraction, number of fractions, and frequency of irradiation still requires refinement in this model. Primates receiving subcapsular autologous dispersed pancreas failed to become normoglycemic and plasma glucose levels never dropped below 12 mmol/L. Postmortem examination revealed diffuse chemical peritonitis associated with surrounding fat necrosis and autodigestion of the retroperitoneal tissues, suggesting that this technique has no clinical application at present.

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Resumen Se emprendió el presente estudio con el fin de evaluar la efectividad de la ciclosporina (CIA) y de la irradiación corporal total (ICT) o la irradiación linfoide total (ILT) en la supresión del rechazo del alotransplante pancreático en mandriles Chacma totalmente pancreatectomizados. Además el estudio incluye nuestros resultados preliminares con el autotransplante subcapsular en el riñón de páncreas autólogo disperso en el primate.La CIA en dosis de 25 mg/kg/día o de 50 mg/kg/día produce una prolongación leve pero significativa de la supervivencia del transplante. Se observó una amplia variación en los niveles séricos de CIA en los primates bajo las mismas dosis orales, y no se vió una clara correlación entre los niveles séricos absolutos de CIA y el rechazo. Aun cuando el auto o alotransplante heterotópico de la cola del páncreas en el mandril fue capaz de mantener normoglicemia en los mandriles pancreatectomizados hasta el rechazo del transplante, la intolerancia a la glucosa, valores bajos de K e hipoinsulinemia fueron todos hallazgos consistentes en pruebas de tolerancia a la glucosa, lo cual sugiere que el transplante representó una masa insuficiente de islote.Los animales que recibieron 76 RAD (ICT) permanecieron normoglicémicos entre 14 y 36 días con una media de 22 días, lo cual indica prolongación de la supervivencia del transplante.Los animales tratados con ILT (600 RAD) mantuvieron la función del transplante entre 7 y 31 días, con una media de 17 días. El régimen óptimo de irradiación en términos de la dosis acumulativa, dosis por fracción, número de fracciones y frecuencia de la irradiación, todavía requiere mayor refinamiento en este modelo.Los primates que recibieron páncreas disperso autólogo en implantación subcapsular no lograron normoglicemia y los niveles plasmáticos de glucosa nunca descendieron de 12 mmol/L. El examen postmortem reveló peritonitis química difusa asociada a necrosis grasa de la vecindad y autodigestión de los tejidos retroperitoneales, lo cual sugiere que esta técnica no tiene aplicación clínica en la actualidad.

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Résumé Cette étude avait pour objectif de mesurer l'efficacité de la cyclosporine A (CYA) et de l'irradiation corporelle totale (ICT) ou de l'irradiation lymphoïde totale (ILT) dans la prévention du rejet des hétérogreffes segmentaires de pancréas, chez les babouins Chacma totalement pancréatectomisés. Nous présentons également nos résultats préliminaires concernant l'autotransplantation de tissu pancréatique dispersé sous la capsule rénale chez le primate.La CYA à la dose de 25 à 50 mg/kg/j entraîne une prolongation discrète mais significative de la survie du greffon. Le taux sérique de CYA varie largement d'un animal à l'autre pour une même dose orale quotidienne, et il n'y a pas de corrélation évidente entre le taux sérique de CYA et la survenue du rejet. Les auto et hétérogreffes de la queue du pancréas en position ectopique sont capables d'assurer la normalisation glycémique chez les babouins pancréatectomisés, jusqu'au rejet de la greffe; mais il persiste constamment une intolérance glucidique, des valeurs basses de K lors des épreuves d'hyperglycémie provoquée, ce qui suggère que la masse d'îlots transplantés est insuffisante.Les animaux recevant une dose de 76 rads (ICT) restent normoglycémiques pendant 14 à 36 jours avec une médiane de 22 jours, ce qui traduit une prolongation modeste mais significative de la survie de la greffe. Les animaux traités par ILT conservent un greffon fonctionnel pendant 7 à 31 jours (médiane = 17 jours). Le protocole optimal d'irradiation pour ce qui est de la dose totale, la dose par fraction, le nombre de fractions et la fréquence des séances d'irradiation, reste à définir dans ce modèle. Les primates greffés avec du pancréas autologue dispersé sous la capsule rénale ne redeviennent pas normoglycémiques, leurs glycémies restant au dessus de 12 mmol/l. L'examen post-mortem révèle des lésions de péritonite chimique diffuse entourées de cyto-stéatonécrose et une autodigestion du tissu rétropéritonéal, ce qui suggère que cette méthode n'a pas d'intérêt clinique pour le moment.

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Supported in part by grants from the Harry Crossley Fund, Medical Research Council, University of Stellen-bosch and The Cape Provincial Administration.     

胰岛移植和胰岛干细胞研究现状

近年来,糖尿病患病率在全球呈现快速增长的趋势,我国人口患病率已接近5％,与发达国家类似。糖尿病已经成为患者和社会的巨大负担。目前,几乎所有1型糖尿病和部分胰岛素依赖的2型糖尿病患者都需要应用外源性胰岛素注射来控制血糖。严格控制血糖不能保证血糖稳定,亦不能避免远期并发症的发生,同时可能导致低血糖晕厥发作相对增多。因此,重建内源性胰岛素分泌系统是近年来研究者关注的热点。全胰腺移植始于20世纪60年代初期,     

Comparison of whole pancreas and pancreatic islet transplantation in controlling nephropathy and metabolic disorders of diabetes.

To compare the long-term effectiveness of whole pancreas transplantation and pancreatic islet transplantation in controlling the metabolic disorders and preventing the kidney lesions of alloxan diabetes, metabolic and morphologic studies were performed in four groups of rats: (1) NC-116 nondiabetic controls; (2) DC-273 untreated alloxan-diabetic controls; (3) PDT-182 rats that received syngeneic pancreaticoduodenal transplants not long after induction of diabetes with alloxan; and (4) IT-92 rats that received an intraportal injection of at least 1500 and usually 2000 syngeneic pancreatic islets soon after induction of diabetes with alloxan. Each month for 24 months after diabetes was well established, body weight and plasma concentrations of glucose and insulin were measured, and five lesions were scored by light microscopy in 50 glomeruli and related tubules in each kidney by a "blind" protocol: glomerular basement membrane thickening, mesangial enlargement, Bowman's capsule thickening, Armanni-Ebstein lesions of the tubules, and tubular protein casts. There were progressive and highly significant increases in the incidence and severity of all five kidney lesions in the diabetic control rats compared with the nondiabetic control rats. No significant differences were found between the kidneys of Group PDT and those of Group NC, demonstrating that whole pancreas transplantation prevented all of the diabetic kidney lesions throughout the 2-year study period. In contrast, within 3-9 months after pancreatic islet transplantation and thereafter, the incidence and severity of the five diabetic kidney lesions were similar in Group IT and Group DC. Whole pancreas transplantation produced precise metabolic control of diabetes throughout the 24 months of study, whereas pancreatic islet transplantation did not accomplish complete metabolic control, particularly beyond the first several months after transplantation. The difference in the completeness of metabolic control achieved by the two types of transplants is the most likely explanation for their sharp difference in effectiveness in preventing diabetic nephropathy.     

异种胰岛细胞移植的研究进展

随着对糖尿病治疗方法的研究进展,异种胰岛移植已被重新认识。笔者综述异种胰岛移植的发展简史、异种胰岛来源、胰岛移植物的制备及鉴定、主要的免疫排斥反应及其防治措施以及展望异种胰岛移植的前景。