Human fetal islet transplantation in type 1 diabetics: comparison of immunological effects between multiple implantation regimens

Previous studies have suggested that the multiple transplants might be equally metabolically efficient to a single regimen for human adult islets. The aim of this study was to compare immunological and metabolic parameters after each of the two regimens of human fetal islets (HFI). Group A single transplants (n = 9) had 180 +/- 20 x 1000 HFI equivalents (IEQs) implanted via a single intramuscular injection. In group B multiple transplants (n = 8) islets were implanted by three consecutive injections of 60 +/- 10 x 1000 IEQs at 7-day intervals. We analyzed the immunological parameters of CD4/CD8 T lymphocyte ratios; islet cell antibodies (ICAs) and insulin antibodies (IAs). We estimated insulin secreting capacity (ISC) as the metabolic parameter. We observed that the CD4+/CD8+ T-cell ratio increased, peaking on day 90, in similar fashion in both groups: day -1: A = 1.18 +/- 0.03 versus B = 1.19 +/- 0.04; on day 90: A = 1.79 +/- 0.09, versus B = 1.75 +/- 0.08 (P = NS) immediately before the decrease in C-peptide levels. Thereafter the ratios rapidly decreased without statistical differences. The levels of ICAs did not change. The levels of IAs, which were increased before transplant, then decreased without statistical differences between the groups. The values of ISC increased after transplant and then decreased similar to the T-cell ratio. Our results demonstrated that regimens of multiple and single HFIs did not show differences in the kinetics of the immunological response presumably mediating graft destruction. The CD4/CD8 ratio increased as the C-peptide level decreased, peaking on day 90 at the time of a decrease in C-peptide. These results may be useful for clinical studies of HFIs for type 1 diabetic patients.

Human fetal islet transplantation in type 1 diabetic patients: Comparison of metabolic effects between single and multiple implantation regimens

Previous studies suggest that multiple transplantations might be equally efficient to a single regimen for human adult islets. The aim of this study was to compare metabolic parameters after each of the two regimens of human fetal islet (HFI) transplantation in type 1 diabetics. In group A (single transplant, n = 9), 180 +/- 20 x 1000 HFI equivalents (IEQs) were implanted by a single IM injection; in group B (multiple transplants, n = 8) islets were implanted as three consecutive injections (60 +/- 10 x 1000 IEQs) at 7-day intervals. We analyzed the metabolic parameters on days -1, 30, 60, 90, 120, 150, and 180 after the procedure. Among the metabolic parameters, we evaluated insulin secretion capacity-ISC (C peptide, RIA), metabolic control (HbA1c, chromatography), and insulin daily dose IDD. We found that C peptide levels increased, peaking on day 90 (A: 0.38 +/- 0.15; B: 0.34 +/- 0.19 nmol/L, P = NS) and then rapidly decreasing without differences, the HbA1c levels and IDD decreased in the same manner without differences between the groups. Our results demonstrate that multiple and single islet transplant regimens are equally efficient to temporarily restore a significant ISC with improvement of metabolic and clinical parameters. The results imply that the two regimens have an equal clinical value.

Relation between course of disease in type 1 diabetes and islet cell antibodies

The aim of this study was to estimate the possibility of predicting the course of type 1 diabetes. We analyzed the importance of islet cell antibody levels and residual beta cell function in 46 newly diagnosed patients with diabetes. Islet cell antibodies (ICAs; Juvenile Diabetes Foundation [JDF] units) were determined at the time of diagnosis by the indirect immunofluorescent method. beta cell function was estimated by C peptide levels (nmol/L) before and after glucagon stimulation at the time of clinical remission. Of the 46 patients, 13 were ICA negative (group A). Among ICA-positive patients, ICAs were < 20 JDF units (group B) in 15, between 20 and 80 JDF in 9 (group C), and > 80 JDF in 9 (group D). In group A, 9 patients had clinical remission for 7.5 +/- 1.7 months. Their basal C peptide level was 0.26 +/- 0.05 nmol/L and it increased after stimulation to 44.5 +/- 2.5%. Ten patients in group B had remission for 6.2 +/- 1.5 months. Their basal C peptide levels (0.28 +/- 0.07 nmol/L) were similarly increased after stimulation (47.5 +/- 2.5%). In group C, all patients had remission and it was of the longest duration (14.7 +/- 1.5 months). They had the highest basal C peptide levels (0.45 +/- 0.12 nmol/L) with increases to 57.5 +/- 3.5%. Seven patients in group D with ICA levels > 80 JDF had a short remission (3.2 +/- 1.2 months) despite good basal C peptide levels (0.42 +/- 0.05 nmol/L) and excellent increases after stimulation (92.5%). Our results suggest that moderate levels of ICA are associated with good residual beta cell function and longer remission. Very high ICA levels (> 80 JDF) at the time of diagnosis despite better beta cell function are associated with short clinical remission. Therefore, high ICA levels could be a marker of strong autoimmune reaction and accelerated depletion of beta cell function.

[Response of pancreatic polypeptide to a protein rich meal in insulin non dependent diabetes melitus and autonomic neuropathy]

Parasympathetic function and plasma hPP response to a protein rich meal were evaluated in 105 insulin non-dependent diabetic patients: 20 with autonomic neuropathy (group A), diagnosed by Clonidin test; 35 patients with neurophysiological evidence of polyneuropath (group B); 30 patients with autonomic neuropathy and polineuropathy (group C), and 20 patients without any sign of neuropathy (group D). Plasma hPP levels were determined by RIA using an anti-hPP antiserum, kindly provided by Prof. S. R. Bloom (Hammersmith Hospital, London). Blood was taken at 0. 45 and 60 minutes after the beginning of the meal. In groups A and C, the meal induced hPP increase was significantly lower than in group D (p 0.001). All group B patients had a marked increase in the peptide, similar to that in diabetics without neuropathy. These result ssuggest that diabetic autonomic neuropathy is associated with dysfunction of hPP secretion, and that the evaluation of hPP response to test meal may be a sensitive and simple method for the assessment of paraympathetic impairment in diabetes.

Detection of compounds in serum inhibiting insulin binding to erythrocyte receptors

The erythrocytes were used as a model system to study insulin receptors in diabetic patients with highly increased insulin resistance. The specific binding of 125I-insulin to erythrocytes of these patients was markedly reduced. When erythrocytes prepared from non-diabetic subjects were exposed to serum of these patients, the decrease of insulin binding was reproduced. The binding of insulin showed a displacement curve that is parallel to the control values over the same range of hormone concentration, even in the case when control erythrocytes were preincubated with serum of diabetics with increased insulin resistance. These results indicate the presence of certain component in blood plasma of examined patients which alters insulin binding to receptors. The developed assay provides an efficient method for detection and identification of substances presented in the serum which can influence the binding of insulin to the specific sites as well as its biological effects.