Local growth factors are beneficial for the autonomic reinnervation of transplanted islets in rats.
ABSTRACT Transplanted islets, being avascular and denervated, receive blood vessels and nerves from the recipient. Reinnervation may account in part for the normalization of islet function in islet transplants. Whether reinnervation is possible to augment is not known.
To explore whether reinnervation of transplanted islets is augmented by local addition of growth factors to the graft, syngeneic islets were transplanted to the pancreas of streptozotocin-diabetic Lewis rats with or without pellets locally releasing nerve growth factor (NGF) and vascular endothelial growth factor (VEGF), alone or in combination. The pellets released growth factors for 14 days at a rate of 20 ng/day. After 7 weeks, pancreatic tissue was processed for immunofluorescence of insulin and the neural markers neuropeptide Y (NPY) and tyrosine hydroxylase (TH).
Islets were larger and more numerous after treatment with NGF (p = 0.024) and with NGF in combination with VEGF (p = 0.044). Similarly, immunostaining for TH and the C-terminal flanking peptide of NPY (C-PON) was more pronounced after treatment with NGF in combination with VEGF than in controls (both p < 0.05).
Local growth factor treatment has a beneficial effect on autonomic reinnervation as well as islet integrity and survival of the graft after islet transplantation in rats.
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ABSTRACT: Pancreatic islets are not fully developed at birth and it is not clear how they are vascularised and innervated. Nerve Growth Factor (NGF) is required to guide sympathetic neurons that innervate peripheral organs and also in cardiovascular system and ovary angiogenesis. Pancreatic beta cells of a transgenic mouse that over-expressed NGF in attracts sympathetic hyper-innervation towards them. Moreover, we have previously demonstrated that adult beta cells synthesize and secrete NGF; however, we do not know how is NGF secreted during development, nor if it might be trophic for sympathetic innervation and survival in the pancreas.We analyzed sympathetic innervation and vasculature development in rat pancreatic islets at different developmental stages; foetal (F19), early postnatal (P1), weaning period (P20) and adults. We temporarily correlated these events to NGF secretion by islet cells. Sympathetic fibres reached pancreatic islets in the early postnatal period, apparently following blood vessels. The maximal number of sympathetic fibres (TH immunopositive) in the periphery of the islets was observed at P20, and then fibres entered the islets and reached the core where beta cells are mainly located. The number of fibres decreased from that stage to adulthood. At all stages studied, islet cells secreted NGF and also expressed the high affinity receptor TrkA. Foetal and neonatal isolated islet cells secreted more NGF than adults. TrkA receptors were expressed at all stages in pancreatic sympathetic fibres and blood vessels. These last structures were NGF-immunoreactive only at early stages (foetal and P0). The results suggest that NGF signalling play an important role in the guidance of blood vessels and sympathetic fibres toward the islets during foetal and neonatal stages and could also preserve innervation at later stages of life.BMC Developmental Biology 07/2009; 9:34. · 2.73 Impact Factor
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ABSTRACT: Efficient stimulation of cycling activity in cultured beta cells would allow the design of new strategies for cell therapy in diabetes. Neural crest stem cells (NCSCs) play a role in beta cell development and maturation and increase the beta cell number in co-transplants. The mechanism behind NCSC-induced beta cell proliferation and the functional capacity of the new beta cells is not known. We developed a new in vitro co-culture system that enables the dissection of the elements that control the cellular interactions that lead to NCSC-dependent increase in islet beta cells. Mouse NCSCs were cultured in vitro, first in medium that stimulated their proliferation, then under conditions that supported their differentiation. When mouse islet cells were cultured together with the NCSCs, more than 35% of the beta cells showed cycle activity. This labelling index is more than tenfold higher than control islets cultured without NCSCs. Beta cells that proliferated under these culture conditions were fully glucose responsive in terms of insulin secretion. NCSCs also induced beta cell proliferation in islets isolated from 1-year-old mice, but not in dissociated islet cells isolated from human donor pancreas tissue. To stimulate beta cell proliferation, NCSCs need to be in intimate contact with the beta cells. Culture of islet cells in contact with NCSCs induces highly efficient beta cell proliferation. The reported culture system is an excellent platform for further dissection of the minimal set of factors needed to drive this process and explore its potential for translation to diabetes therapy.Diabetologia 05/2012; 55(7):2016-25. · 6.49 Impact Factor
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ABSTRACT: Nerve growth factor (NGF) belongs to the family of neurotropic proteins NGF is markedly expressed in proteinuric renal diseases and in end-stage renal disease; it might be involved in kidney physiopathology. To date, little is known about NGF concentrations in kidney transplant recipients (KTRs). Because NGF exerts its action on cell survival and differentiation, tissue repair, and inflammatory responses, it may also be implicated in the pathogenesis of chronic allograft nephropathy. The aim of this study was to determine circulating NGF concentrations in KTRs and to ascertain their use as a prognostic marker for kidney transplant outcomes. Using enzyme-linked immunosorbent assay, we performed quantification of NGF in the serum of 40 prevalent KTRs at baseline and at 6 months. NGF concentrations in KTRs averaged 1.16 ± 0.67 ng/mL. They negative-linearly correlated with recipient age. Logistic multivariate regression analysis showed NGF to be independently associated with increased proteinuria over the 6-month follow-up. Our data demonstrated that serum concentrations of NGF in KTRs were elevated and that they could be considered to be a prognostic marker in kidney transplantation.Transplantation Proceedings 09/2013; 45(7):2654-6. · 0.95 Impact Factor