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For most lysosomal storage diseases (LSDs) affecting the CNS, there is currently no cure. The BBB, which limits the bioavailability of drugs administered systemically, and the short half-life of lysosomal [...]

Recovery from type 1 diabetes requires restoration or β-cell mass. We have shown that transgenic mice expressing insulin-like growth factor-I (IGF-I) in β-cells regenerate β-cell mass after diabetes induction (STZ). Vascularization plays a key role in the formation of pancreatic islets and increased vascularization in VEGF transgenic mice leads to increased β-cell mass. In basal conditions, expression of VEGF was 3.5-fold higher in IGF-I transgenic compared with control islets. However, the number of capillaries within the islets were similar in both groups of mice, indicating that angiogenesis was not increased. Expression of SDF-1, a chemo-attractant for bone marrow cells (BMC), was normal in non-diabetic conditions but increased after STZ-treatment. Therefore, we also investigated whether IGF-I expression in β-cells could increase BMC recruitment and differentiation into β-cells. To this end, BMC from β-actin/green fluorescent protein (GFP) transgenic mice were transplanted into lethally irradiated IGF-I transgenic mice. GFP+ cells with an hematopoietic phenotype (CD45+) were found in the interstitium of endocrine pancreatic tissue. In contrast, very few insulin+/GFP+ cells were detected in islets from these animals. Thus, IGF-I overexpression did not result in recruitment and differentiation of BMC into β-cells. Moreover, islets from STZ-treated bone marrow transplanted transgenic mice co-expressed IGF-I, suggesting that β-cells in such islets originated, probably by replicatiun, from pre-existing β-cells. Indeed, IGF-I expressing transgenic islets showed an increase in IRS2, total AKT, P-AKT, and P-FOXO 1 that lead to decreased levels of p27 mRNA inducing higher CDK4 expression, consistent with increased β-cell replication. These data suggest that IGF-I expression regenerates the endocrine pancreas during diabetes by B-cell replication rather than BMC differentiation. [ABSTRACT FROM AUTHOR]

Blood-retinal barrier (BRB) breakdown is an important feature of non-proliferative diabetic retinopathy and other diverse ocular disorders. The leakage of plasma components through a disrupted barrier can alter the extracellular milieu, affect retinal neuronal function and eventually lead to macular edema, a major cause of visual loss. Several growth factors, such as Insulin Growth Factor-I (IGF-I) are believed to be involved in pathological vascular permeability. However, the source of increased intraocular IGF-I in diabetic retinopathy is controversial and the relative contributions of local or serum IGF-I is unknown. Here, we investigated BRB breakdown in normoglycemic/normoinsulinemic transgenic mice overexpressing IGF-I in the retina. IGF-I induced a progressive increase in vascular leakage beginning at 3 month of age. Transgenic vessels were permeable to both low molecular weight compounds and proteins. In vivo fluorescence imaging confirmed extravasation of solutes in transgenic eyes. Electron microscopy analyses of HRP-injected transgenic retinas revealed increased transcytosis and increased paracellular flux through disrupted endothelial tight junctions. The latter was accompanied by altered expression of the tight junction complex proteins. To assess the contribution of circulating IGF-I to BRB breakdown we studied another transgenic animal model expressing growth hormone in the liver. These mice had increased serum but normal intraocular IGF-I levels. Transgenic animals had morphologically normal eyes and BRB breakdown was not detectable even with the most sensitive techniques. Furthermore, long term diabetes did not favour the appearance of a leaky phenotype in these animals. In conclusion, this study provides evidence for a key role of increased intraocular IGF-I in the breakdown of blood-retinal barrier. [ABSTRACT FROM AUTHOR]

Blood-retinal barrier (BRB) breakdown is a key event in diabetic retinopathy and other ocular disorders that leads to increased retinal vascular permeability. This causes edema and tissue damage resulting in visual impairment. Insulin-like growth factor-I (IGF-I) is involved in these processes, although the relative contribution of increased systemic versus intraocular IGF-I remains controversial. Here, to elucidate the role of this factor in BRB breakdown, transgenic mice with either local or systemic elevations of IGF-I have been examined. High intraocular IGF-I, resulting from overexpression of IGF-I in the retina, increased IGF-I receptor content and signaling and led to accumulation of vascular endothelial growth factor. This was parallel to up-regulation of vascular Intercellular adhesion molecule I and retinal infiltration by bone marrow-derived microglial cells. These alterations resulted in increased vessel paracellular permeability to both low and high molecular weight compounds in IGF-I-overexpressing retinas and agreed with the loss of vascular tight junction integrity observed by electron microscopy and the altered junctional protein content. In contrast, mice with chronically elevated serum IGF-I did not show alterations in the retinal vasculature structure and permeability, indicating that circulating IGF-I cannot initiate BRB breakdown. Consistent with a key role of IGF-I signaling in retinal diseases, a strong up-regulation of the IGF-I receptor in human retinas with marked gliosis was also observed, Thus, this study demonstrates that intraocular IGF-I, but not systemic IGF-I, is sufficient to trigger processes leading to BRB breakdown and increased retinal vascular permeability. Therefore, therapeutic interventions designed to counteract local IGF-I effects may prove successful to prevent BRB disruption. [ABSTRACT FROM AUTHOR]

Diabetes is a complex metabolic disease that exposes patients to the deleterious effects of hyperglycemia on various organs. Achievement of normoglycemia with exogenous insulin treatment requires the use of high doses of hormone, which increases the risk of life-threatening hypoglycemic episodes. We developed a gene therapy approach to control diabetic hyperglycemia based on co-expression of the insulin and glucokinase genes in skeletal muscle. Previous studies proved the feasibility of gene delivery to large diabetic animals with adeno-associated viral (AAV) vectors. Here, we report the long-term (∼8 years) follow-up after a single administration of therapeutic vectors to diabetic dogs. Successful, multi-year control of glycemia was achieved without the need of supplementation with exogenous insulin. Metabolic correction was demonstrated through normalization of serum levels of fructosamine, triglycerides, and cholesterol and remarkable improvement in the response to an oral glucose challenge. The persistence of vector genomes and therapeutic transgene expression years after vector delivery was documented in multiple samples from treated muscles, which showed normal morphology. Thus, this study demonstrates the long-term efficacy and safety of insulin and glucokinase gene transfer in large animals and especially the ability of the system to respond to the changes in metabolic needs as animals grow older.

Retinal dystrophies (RD) are major causes of familial blindness and are characterized by progressive dysfunction of photoreceptor and/or retinal pigment epithelium (RPE) cells. In this study, we aimed to evaluate and compare the therapeutic effects of two pluripotent stem cell (PSC)-based therapies. We differentiated RPE from human embryonic stem cells (hESCs) or human-induced pluripotent stem cells (hiPSCs) and transplanted them into the subretinal space of the Royal College of Surgeons (RCS) rat. Once differentiated, cells from either source of PSC resembled mature RPE in their morphology and gene expression profile. Following transplantation, both hESC- and hiPSC-derived cells maintained the expression of specific RPE markers, lost their proliferative capacity, established tight junctions, and were able to perform phagocytosis of photoreceptor outer segments. Remarkably, grafted areas showed increased numbers of photoreceptor nuclei and outer segment disk membranes. Regardless of the cell source, human transplants protected retina from cell apoptosis, glial stress and accumulation of autofluorescence, and responded better to light stimuli. Altogether, our results show that hESC- and hiPSC-derived cells survived, migrated, integrated, and functioned as RPE in the RCS rat retina, providing preclinical evidence that either PSC source could be of potential benefit for treating RD.