Long-Term Metabolic Control by Rat Islet Grafts Depends on the Composition of the Implant

Abstract

This study examines whether the loss of metabolic control in initially normalized islet transplants can result from the inadequate composition of the donor tissue. Streptozotocin-induced diabetic rats were followed for 64 weeks after the intraportal injection of islet isografts with different composition. The implantation of 2.3 million beta-cells (10(7)/kg body wt) as particles (>100 microm diameter) of primarily insulin-positive (70%) and glucagon-positive (20%) cells succeeded in a long-term normalization of 2-h fasting glycemia, glucose tolerance, and serum fructosamine. The same metabolic control was achieved in animals with short and long durations of diabetes or when grafts were implanted under the kidney capsule. At posttransplantation (PT) week 64, insulin reserves were 60% lower than those in age-matched controls, which may account for the glucose intolerance in a few old recipients. The same type of graft containing 0.7 million beta-cells (4 x 10(6)/kg body wt) corrected these metabolic parameters for more than 12 weeks; the proportionally lower insulin reserves were sufficient for the long-term correction of 2-h fasting glycemia, but did not avoid glucose intolerance in older recipients. When the higher beta-cells number (10(7)/kg body wt) was injected as smaller particles (<100 mpm diameter) of lower purity (55% insulin-positive) and negligible glucagon content (<5% glucagon-positive), the metabolic parameters were also corrected for 12 weeks PT but then progressively returned to overt diabetes (6 of 10) or glucose intolerance (4 of 10). We concluded that long-term metabolic normalization can be achieved by islet implants in the liver or under the kidney capsule. The loss of metabolic control in older animals can be caused by the inadequate composition of the graft, with the number of beta-cells, the proportion of other endocrine and nonendocrine cells, and the particle size as influential variables.

Length of metabolic normalization after rat islet cell transplantation depends on endocrine cell composition of graft and on donor age

“…The present study confirms that intraportal injection of islet cell aggregates containing 1 to 2 million beta cells corrects overt diabetes in streptozotocin-diabetic rats with a body weight of 200 g [9,15,17]. This effect is achieved with beta cells isolated from young (10 weeks) as well as from middle-aged (30 weeks) rats.…”

“…At the end of culture, the preparations were gently removed from the dishes and samples were taken for insulin, glucagon and DNA assays, and for electron microscopy and immunocytochemistry [16]. The data were used to calculate the number of beta-and alpha-cells in the graft at the time of implantation; the method used for this calculation has been previously described [9,17]. After sampling, the islet cell preparations were injected into the portal vein of diabetic recipients [18].…”

“…It was often not clear whether this delayed failure was due to an insufficient graft, an inadequate implantation site or an immune reactivity [1][2][3][4][5][6][7][8]. We recently observed that the composition of the donor tissue can be responsible for a late loss of metabolic control in streptozotocin-diabetic rats which had been successfully treated by islet cell transplantation [9]. Number of beta cells, proportion of other endocrine and nonendocrine cells and particle size were found to be potentially influential variables.…”

A Novel Method for the Assessment of Cellular Composition and Beta-Cell Viability in Human Islet Preparations

“…More conventional techniques such as immunohistochemical (23,24) and electron microscopic (EM) analysis rely on subjective interpretation of the results and scoring based on observation of samples by the operator(s). The LSC hardware and software provide objective analysis of substantially higher number of cells (e.g.…”

In vitro generation of insulin-producing beta cells from adult exocrine pancreatic cells

“…Under mild anaesthesia with ketamine (75 mg/kg) and a mixture of medetomidine, methyl-parahydroxybenzoate and propyl-parahydroxybenzoate (1 mg/kg) nude mice were injected intravenously with 70 mg/kg alloxan 3 h prior to transplantation. Mice were then anaesthetised with ketamine (75 mg/kg) and a mixture of medetomidine, methyl-parahydroxybenzoate and propyl-parahydroxybenzoate (4 mg/kg) and cell pellets of 50,000 to 100,000 insulin-positive cells were implanted under the kidney capsule [24]. Blood glucose levels were monitored in samples obtained from the tail vein of fed mice by using Glucocard Memory strips (A. Menarini Diagnostics Benelux, Zaventem, Belgium).…”