Persistent reversal of diabetes by transplantation of fetal pig proislets into nude mice.

Facing the limited availability of human adult and fetal pancreases, fetal pig proislets (pancreatic islet precursors) were investigated in view of several inherent advantages. Six litters of fetuses of mean +/- SE gestational age 75 +/- 3 days were obtained from commercially available farm pigs. Pancreatic tissue was gently digested with collagenase, then a 10-day culture was performed. During culture, fetal proislets showed no insulin response to glucose alone but a significant response to glucose plus theophylline. The insulin content per microgram of DNA in the cultured proislets continuously increased. Histological examination by immunoperoxidase staining showed that, apart from single insulin- and glucagon-positive cells, there were no discrete islets in the pancreatic tissue and the cultured proislets. Diabetes was induced with streptozocin (STZ) in eight nude mice 3-4 wk after proislet transplantation and in another eight nude mice without transplantation. During the initial week, blood glucose levels of mice in both groups increased rapidly. The mean +/- SE peak value of blood glucose levels in the transplanted group was 20.4 +/- 2.0 mM and was 20.1 +/- 1.3 mM in the group without transplantation. Simultaneously, body weight decreased from 29.5 +/- 0.7 to 21.5 +/- 0.9 g and from 27.9 +/- 0.7 to 19 +/- 1 g in the groups, respectively. Afterward, blood glucose levels of mice in the transplanted group gradually decreased, and normoglycemia was achieved in all mice within 50 +/- 13 days after injection of STZ, i.e., 74 +/- 13 days after transplantation. The group without transplantation persistently maintained blood glucose levels greater than 16.7 mM.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-specific IgG and IgE antibody response in type I diabetic subjects exclusively treated with human insulin (recombinant DNA).

Bovine and porcine insulins elicit specific antibody response in diabetic subjects after a few months of treatment. In seven type I diabetic individuals who were exclusively treated with human insulin (recombinant DNA) each month, sera were examined for the development of insulin-specific IgG and IgE antibodies. In all patients (except one), IgG antibodies occurred after 2 mo and tended to further increase in concentration after 5-6 mo. IgE antibodies could be detected after 1 mo with a further increase after 2-3 mo and a marked decline thereafter. No patient exhibited allergic symptoms. The results indicate that physicochemical properties of insulin preparations used for treatment and the route of administration are of more importance for immunogenicity than species differences of insulin.

Clinical islet transplantation--registry report, accomplishments in the past and future research needs.

This review provides the results of a recent analysis of the Islet Transplant Registry on clinical adult islet transplants performed worldwide through June 30, 1992. Between December 12, 1893 and June 30, 1992, 167 adult islet transplants were performed at 25 institutions worldwide, including 104 at 9 institutions in North America, 62 at 15 institutions in Europe, and 1 elsewhere. The total number of diabetic patients reported to be insulin independent after adult islet allotransplantation through June 30, 1992, was 19. In an analysis by era, the percentage of patients that showed positive basal C-peptide levels (i.e., > or = 1 ng/mL at > or = 1 mo) posttransplant, and that became insulin independent (> 1 wk) in the 1985-1989 era (n = 35 cases) were 20% and 6%, and in the 1990-1992 era (n = 69 cases) were 64% and 20%, respectively, and thus have improved significantly (p < 0.001 and p < 0.05). For the 1990-1992 period, the percentage of patients who showed positive basal C-peptide levels post-transplant, and who became insulin independent in the single donor pancreas group (n = 31 cases) were 52% and 13%, and in the multiple donor pancreata group (n = 36 cases) were 75% and 28%, respectively. Islet graft function rates were nearly identical for grafts prepared from pancreata stored < or = 6 h (n = 27) and > 6 < or = 12 h (n = 29), so that 67% and 72% showed positive basal C-peptide levels, and 30% and 21% of the recipients became insulin independent, respectively. No single patient showed islet graft function sufficient to allow withdrawal from insulin, if the pancreata have been stored for more than 12 h. In regard to recipient category for the six groups, namely IAK (islet after kidney), SIK (simultaneous islet kidney transplantation), SIL (simultaneous islet liver transplantation), SIL(C) (simultaneous islet liver transplantation after cluster operation), SIKL (simultaneous islet kidney liver transplantation), and SIH-L (simultaneous islet heart-lung transplantation), the number of patients who showed positive basal C-peptide levels post-transplant was 11 (58%), 17 (57%), 5 (83%), 8 (80%), 1 (50%), and 0 (0%), and the number of insulin independent patients was 4 (21%), 4 (13%), 0 (0%), 6 (60%), 0 (0%), and 0 (0%), respectively. Comparing the two largest recipient categories, namely IAK and SIK, no difference in the outcome of these transplants was apparent.(ABSTRACT TRUNCATED AT 400 WORDS)

Islet transplantation as treatment of type 1 diabetes: from experimental beginnings to clinical application.

Experimental islet transplantation started more than 30 years ago when it was discovered that isolation of the islets of Langerhans from the exocrine tissue of the pancreas was possible with collagenase. In numerous studies over the following years in rodents it was shown that transplantation of a sufficient number of islets into the liver via the portal vein shortly after diabetes induction of the recipient resulted in normoglycemia, aglycosuria, normal body weight and the typical diabetic late complications were prevented. However, those results were limited for the syngeneic system, when allogeneic islets were transplanted rejection occurred within a few days. Immunosuppressive regimen showed only limited success in rodents while immunoalteration procedures (culture at low temperatures, UV light irradiation, cryopreservation etc.) were capable to prolong the survival of islets up to 200 days. In contrast to the rodent model in larger animals as pigs, dogs and monkeys immunosuppressive drugs (single and in combination) resulted in marked prolongation of allograft survival while immunoalteration of islets with those animals was less successful. Because a broader use of islet transplantation in man will lead to shortage of donor organs xenotransplantation may be possibly a solution which is briefly mentioned.--Finally, new strategies regarding the production of human insulin producing cells for transplantation purposes are discussed.--In summary, experimental islet transplantation has paved the way for using this treatment in human patients.

Islet cell transplantation in diabetes mellitus--from bench to bedside.

Replacement of the patient's islets of Langerhans either by pancreas transplantation or by isolated islet transplantation is the only treatment of type I diabetes mellitus to achieve an insulin-independent, constant normoglycemic state. The expense for this benefit is the need for immunosuppressive treatment of the recipient with all its potential risks. Thus, indications for pancreas or islet transplantations at present exist almost exclusively in patients with end-stage renal disease who are waiting on dialysis for a kidney graft or in diabetics with an established kidney graft obliged to be immunosuppressed. Islet transplants possess significantly potential advantages over whole-gland transplants: it is a simple procedure with only small risk, if any; it offers the potential advantages of pre-transplant reduction of immunogenicity thus possibly obviating the need for continuous life-long recipient immunosuppression and it offers the future feasibility of transplanting heterologous (pig) islets. The effectiveness of this concept was demonstrated in animal experiments and may be successfully transferred into the clinical situation. In this case, the indications for islet transplantation may be extended to non-uremic type I diabetics including diabetic children. This group of patients is the ultimate target group for this most direct and appealing concept of treating type I diabetes. As of 1994, more than 200 adult islet allografts were reported to the International Islet Transplant Registry (ITR) at the Justus-Liebig-University, Giessen, Germany. A detailed analysis of 75 well-documented cases grafted between 1990 and 1993 revealed a one-year survival rate of the patients and islets of 95% and 28% (in terms of significant basal C-peptide secretion), respectively, and insulin independence was achieved in 11% of the cases after simultaneous islet-kidney (SIK) or islet-after-kidney (IAK) transplants. At present, there is no clinical data available and the follow-up studies of the posttransplant period are too short to draw any conclusions concerning the effects of islet transplants on diabetic secondary complications. Moreover, islet transplantation is still a clinical investigational procedure. Obviously, a number of fundamental steps will have to be taken before the appealing concept of transplanting adult pancreatic islets can attain clinical importance in the treatment of type I diabetic subjects. Islet cell transplantation has come the long way from animal experiments to successful clinical application, but, more research at the bench has to be performed before islet cell transplants will be successfully performed in non-uremic, non-kidney transplanted type I diabetic patients.

Efficacy of benfotiamine versus thiamine on function and glycation products of peripheral nerves in diabetic rats.

In rats with streptozotocin (STZ) induced diabetes the effect of (watersoluble) thiamine nitrate and of (lipidsoluble) benfotiamine on peripheral nerve function (motor nerve conduction velocity) as well as on the formation of advanced glycation end-products in peripheral nerve tissue was studied. In one group of animals drug administration was started immediately after diabetes induction (prevention study) and in another group two months after diabetes induction (treatment study). Motor nerve conduction velocity (NCV) dropped by 10.5% in diabetic animals, carboxymethyl-lysine (CML) rose to a 3.5fold concentration, deoxyglucosone (3DG)-type AGE formation was increased 5.1fold compared with controls. After three months preventive administration of both vitamin B(1) preparations NCV had increased substantially compared with results in diabetic controls. It was nearly normal after six months with benfotiamine, while the administration of thiamine nitrate resulted in no further amelioration. NCV was nearly normalized after six months of benfotiamine application but not with thiamine. Furthermore, benfotiamine induced a major inhibition of neural imidazole-type AGE formation and completely prevented diabetes induced glycoxidation products (CML). Treatment with thiamine did not significantly affect AGE or cmL levels. Unlike treatment with water-soluble thiamine nitrate timely administration of liposoluble prodrug benfotiamine was effective in the prevention of functional damage and of AGE and cmL formation in nerves of diabetic rats.

Islet transplantation. The connection of experiment and clinic exemplified by the transplantation of islets of Langerhans.

Since approximately 25 years islet transplantation as a mean for the treatment of diabetes has been developed from early attempts in rodents to first clinical applications in man in recent years. The review describes the results obtained in diabetic rats including metabolic effects as well as prevention of late complications. In the syngeneic system (Lewis-rats) the intraportal transplantation of 1,000-2,000 isolated islets may cure streptozotocin-induced diabetes for the whole lifespan of the animal. In the allogeneic system (across a major histocompatibility barrier), however, isolated islets are highly immunogenic. According to present knowledge, mainly class-II antigen bearing cells are responsible while the role of the endocrine cells seems to be less important. By various in vitro methods (e.g. low temperature culture at 24 degrees C) it was possible to induce immunoalteration of allogeneic islets which was followed by long-term acceptance by the host in rodents. Whether the same technique is effective in larger animals and in man remains open. New technologies for the isolation of high numbers of pure islets from human pancreatic glands have been the key for the use of islet transplantation in man in several centers. The review describes the details regarding institutions as well as results in patients on the basis of the International Islet Transplant Registry which is located at Giessen University. Although longer lasting insulin independency (longest lasting effect 2 1/2 years) has been observed only in a few patients, islet transplantation has been proven to be a very safe procedure for the patient. It is hoped that with increasing experiences regarding the factors which at present limit the function as number and quality of islets, immunosuppressive protocols etc. islet transplantation will develop to a definite alternative to whole-organ transplantation. One of the most important challenges for modern medicine is the fact of a worldwide increase of diabetic long-term complications such as kidney failure, coronary and peripheral vascular disease, blindness and neuropathy. Although intensified insulin treatment in a small percentage of patients may moderate morbidity and mortality, from experimental work there is sufficient evidence suggesting that only the restoration of normoglycemia early in the course of the disease may prevent complications. This, however, can only be achieved by the replacement of the destroyed islets of Langerhans either by transplantation of an intact vascularised pancreas or by isolated islets.(ABSTRACT TRUNCATED AT 400 WORDS)

[Experimental and clinical islets transplantation. Current status]. / Experimentelle und klinische Inseltransplantation. Gegenwärtiger Stand.

25 years have passed since the first enzymatic isolation of islets of Langerhans from the rat pancreas. During this period of time, it could be demonstrated that transplantation of syngeneic islets intraportally into streptozoticin-treated diabetic recipients (rat, mouse) does not only guarantee long term normoglycemia but inhibits also typical late complications of the disease. Allogeneic islets, however, exhibit strong immunogenicity (rejection within a few days) which can be overcome by various immunomodulating in vitro measures of the islets before transplantation. Isolated islets have been successfully transplanted also in larger animals as dogs and pigs, when transplanted in an autologous or allogeneic system. In human diabetes the success rate of islet transplantation up to now is low and cannot be compared with the results in experimental diabetes. The reasons are manyfold: islet damage due to long ischemia time, low number of islets, low purity, lack of diagnostic markers which indicate rejection, autoimmune destruction. The fact that in the meantime a few patients remain insulin independent after a single islet transplant with the maximum of 2 years indicates however that this method in principle may serve as a tool for the treatment of diabetes. This is underlined by several advantages compared to pancreatic organ transplantation as low risk of the procedure for the recipient and the possibility of repeated transplantation. In addition, in the future xenotransplantation of (porcine) islets might be feasible.

The effect of two new glucosidase inhibitors on blood glucose in healthy volunteers and in type II diabetics.

Two new glucosidase inhibitors (BAY m 1099 and BAY o 1248) were studied in volunteers and type II diabetics under various conditions. In 6 non-diabetic controls BAY m 1099 when given 3 X 50 mg/day caused a marked depression of the post-meal glucose rise. The effect was found to be more marked after breakfast than after lunch or after dinner. In type II diabetics BAY m 1099, when given in a dose of 2 X 25 mg/day over one week, had no significant effect on post-meal glucose or serum insulin levels. BAY o 1248, when given as a single dose of 15 mg in the morning to type II diabetics, induced a significant decrease of post-meal glucose rise (35 mg/dl after breakfast, 25 mg/dl after lunch) when compared to placebo. Although in parallel serum insulin levels were slightly lower, this change was statistically not significant. The drug reduced glycosuria by 50%. Both compounds induced side effects, such as flatulence or diarrhea when given in therapeutically effective amounts, but were tolerable in most cases. On a weight basis BAY o 1248 was found to have greater therapeutic effects than BAY m 1099. Both drugs can be recommended for use in unsatisfactorily controlled type II diabetics. Further studies should concentrate on the critical dosage which may strike a satisfactory balance between effects and side effects.

Nephroprotective effects of nitrendipine in hypertensive type I and type II diabetic patients.

Hypertension is significantly involved in the progression of diabetic nephropathy and in the development of end stage renal disease in both type I and type II diabetes mellitus. We have investigated whether long-term monotherapy with a calcium antagonist, nitrendipine, prevents the development of overt diabetic nephropathy in type I and type II diabetic patients with mild to moderate hypertension and persistent microalbuminuria (ie, incipient nephropathy). After a 4-week run-in and washout period, respectively, 25 patients met the inclusion criteria. Twenty-two patients (six with type I and 16 with type II diabetes) completed the 12-month study. Twelve months of treatment with nitrendipine resulted in a significant reduction in systolic blood pressure in patients with type I (157.5 +/- 8.1 mm Hg v 135.8 +/- 4.2 mm Hg, P < 0.05) and type II (163.1 +/- 4.3 mm Hg v 135.9 +/- 3.6 mm Hg, P < 0.001) diabetes. A significant reduction also was seen in diastolic blood pressure (91.7 +/- 1.7 mm Hg v 79.2 +/- 3.5 mm Hg in type I diabetic patients, P < 0.01; 94.7 +/- 1.4 mm Hg v 78.1 +/- 1.5 mm Hg in type II diabetic patients, P < 0.001). A significant reduction in albuminuria was associated with the blood pressure reduction in both type I (57.8 +/- 11.9 mg/24 hr v 24.9 +/- 5.9 mg/24 hr, -57%) and type II (134.6 +/- 20.7 mg/24 hr v 70.3 +/- 16.8 mg/24 hr, -48%) diabetic patients. The mean glomerular filtration rate increased by 21% (112 +/- 12 mL/min v 135 +/- 14 mL/min) and by 23% (106 +/- 12 mL/min v 130 +/- 14 mL/min) in type I and type II diabetic patients, respectively. No significant changes were found in renal plasma flow rates or in serum concentrations of beta 2-microglobulin. With the exception of a significant (P < 0.05) reduction in hemoglobin A1 concentration in type II diabetic patients after 3 months of treatment with nitrendipine, fasting blood glucose, hemoglobin A1, residual beta-cell function (C-peptide levels), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and body mass index remained essentially unchanged during follow-up. These findings suggest that 12 months of monotherapy with the dihydropyridine-type calcium antagonist nitrendipine reduced albuminuria and increased the lowered glomerular filtration rate without adverse effects on glucose and lipid control.(ABSTRACT TRUNCATED AT 400 WORDS)

Successful cryopreservation of fetal porcine proislets.

This study reports the cryopreservation of purified fetal pig proislets (FPP) which were isolated by a culture technique. The FPP were equilibrated with 2 M dimethyl sulfoxide (Me2SO), cooled at a rate of 0.25 degrees C/min to -40 degrees C, transferred to liquid nitrogen (-196 degrees C), stored for 2 h to 2 months at -196 degrees C, and thawed in a 37 degrees C water bath. The morphology of frozen-thawed FPP was similar to that of noncryopreserved FPP. One hundred percent recovery of response capacity was achieved when tested with 16.7 mM glucose plus 10 mM theophylline. We have recently shown that streptozotocin is not toxic to FPP. Accordingly, we transplanted a standardized dose (10-15 mg/mouse) of either cultured of frozen-thawed FPP beneath the renal capsule of nude mice. Three to four weeks later the recipients of the FPP were rendered diabetic by iv streptozotocin. All of the mice transplanted with cultured FPP and seven of eight mice receiving cryopreserved FPP achieved normoglycemia, 74.8 +/- 32.9 and 54.7 +/- 8.1 days (P > 0.05) after transplantation. An intraperitoneal glucose tolerance test in the mice of both groups showed a flatter response to glucose compared to those of normal controls. Grafts removed from the mice with normoglycemia for > 3 weeks, in both groups, had the capacity to secrete insulin in response to 16.7 mM glucose alone and 16.7 mM glucose plus 10 mM theophylline during in vitro perifusion. Histological examination revealed that the extent of differentiation and development, in vivo of cryopreserved FPP was comparable with that of cultured FPP. These data indicate that cryopreservation, with the protocol used here, is successful in maintaining functional viability of frozen-thawed FPP. This study is valuable for clinical islet transplantation research.