The loss of or decreased functional pancreatic β-cell is a major cause of type 1 and type 2 diabetes. Previous studies have shown that adult β-cells can maintain their ability for a low level of turnover through replication and neogenesis. Thus, a strategy to prevent and treat diabetes would be to enhance the ability of β-cells to increase the mass of functional β-cells. Consequently, much effort has been devoted to identify factors that can effectively induce β-cell expansion. This review focuses on recent reports on small molecules and protein factors that have been shown to promote β-cell expansion.
Cell Communication ; genetics ; Cell Differentiation ; genetics ; Cell Proliferation ; Diabetes Mellitus, Type 1 ; genetics ; pathology ; Diabetes Mellitus, Type 2 ; genetics ; pathology ; Humans ; Insulin-Secreting Cells ; chemistry ; metabolism ; pathology

BACKGROUNDTherapeutic angiogenesis has been shown to promote blood vessel growth and improve tissue perfusion. Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis. However, it has side effects that limit its therapeutic utility in vivo, especially at high concentrations. This study aimed to investigate whether an intramuscular injection of a genetically engineered zinc finger VEGF-activating transcription factor modulates the endothelial progenitor cells (EPC) and promotes therapeutic angiogenesis in a hindlimb ischemia model with type 1 diabetes.

METHODSAlloxan (intravenous injection) was used to induce type I diabetes in C57BL/6 mice (n = 58). The ischemic limb received ZFP-VEGF (125 µg ZFP-VEGF plasmid in 1% poloxamer) or placebo (1% poloxamer) intramuscularly. Mice were sacrificed 3, 5, 10, or 20 days post-injection. Limb blood flow was monitored using laser Doppler perfusion imaging. VEGF mRNA and protein expression were examined using real-time PCR and ELISA, respectively. Capillary density, proliferation, and apoptosis were examined using immunohistochemistry techniques. Flow cytometry was used to detect the EPC population in bone marrow. Two-tailed Student's paired t test and repeated-measures analysis of variance were used for statistical analysis.

RESULTSZFP-VEGF increased VEGF mRNA and protein expression at 3 and 10 days post-injection, and increased EPC in bone marrow at day 5 and 20 post-injection compared with controls (P < 0.05). ZFP-VEGF treatment resulted in better perfusion recovery, a higher capillary density and proliferation, and less apoptosis compared with controls (P < 0.05).

CONCLUSIONSIntramuscular ZFP-VEGF injection promotes therapeutic angiogenesis in an ischemic hindlimb model with type 1 diabetes. This might be due to the effects of VEGF on cell survival and EPC recruitment.

Animals ; Diabetes Mellitus, Type 1 ; metabolism ; Endothelial Progenitor Cells ; metabolism ; Flow Cytometry ; Hindlimb ; pathology ; Ischemia ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

The generation of disease-specific induced pluripotent stem cell (iPSC) lines from patients with incurable diseases is a promising approach for studying disease mechanisms and drug screening. Such innovation enables to obtain autologous cell sources in regenerative medicine. Herein, we report the generation and characterization of iPSCs from fibroblasts of patients with sporadic or familial diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), juvenile-onset, type I diabetes mellitus (JDM), and Duchenne type muscular dystrophy (DMD), as well as from normal human fibroblasts (WT). As an example to modeling disease using disease-specific iPSCs, we also discuss the previously established childhood cerebral adrenoleukodystrophy (CCALD)- and adrenomyeloneuropathy (AMN)-iPSCs by our group. Through DNA fingerprinting analysis, the origins of generated disease-specific iPSC lines were identified. Each iPSC line exhibited an intense alkaline phosphatase activity, expression of pluripotent markers, and the potential to differentiate into all three embryonic germ layers: the ectoderm, endoderm, and mesoderm. Expression of endogenous pluripotent markers and downregulation of retrovirus-delivered transgenes [OCT4 (POU5F1), SOX2, KLF4, and c-MYC] were observed in the generated iPSCs. Collectively, our results demonstrated that disease-specific iPSC lines characteristically resembled hESC lines. Furthermore, we were able to differentiate PD-iPSCs, one of the disease-specific-iPSC lines we generated, into dopaminergic (DA) neurons, the cell type mostly affected by PD. These PD-specific DA neurons along with other examples of cell models derived from disease-specific iPSCs would provide a powerful platform for examining the pathophysiology of relevant diseases at the cellular and molecular levels and for developing new drugs and therapeutic regimens.
Alzheimer Disease/genetics/*pathology ; Cell Differentiation ; Cells, Cultured ; Diabetes Mellitus, Type 1/genetics/*pathology ; Drug Discovery/*methods ; Fibroblasts/cytology/metabolism/pathology ; Gene Expression ; Humans ; Induced Pluripotent Stem Cells/cytology/metabolism/*pathology ; Muscular Dystrophy, Duchenne/genetics/*pathology ; Parkinson Disease/genetics/*pathology

OBJECTIVETo compare the retinal function and retinal vascular pathologies in C57BL/6 and eNOS-knockout (eNOS(-/-)) mouse models of type 1 diabetes mellitus (T1DM) induced by streptozotocin (STZ).

METHODST1DM models were established in 6- to 8-week-old C57BL/6 and eNOS(-/-) mice by intraperitoneal STZ injection. Electroretinogram (ERG) examination, fluorescein angiography (FFA), immunofluorescence staining and retinal ganglion cell counts were carried out before and after STZ injection.

RESULTSDiabetic C57BL/6 and eNOS(-/-) mice showed significantly lowered a-wave and b-wave amplitude in ERG and reduced number of retinal ganglion cells (P<0.05), and the retinal vessels in diabetic eNOS(-/-) mice became tortuous. Compared with diabetic C57BL/6 mice, diabetic eNOS(-/-) mice showed more severe pathological changes in retinal function and retinal vessels with also more rapid onset of pathologies.

CONCLUSIONCompared with C57BL/6 mouse models, eNOS(-/-) mouse models of T1DM can better represent the occurrence and development of diabetic retinopathy, thus providing an ideal model for diabetes and diabetic retinopathy studies.

Animals ; Diabetes Mellitus, Experimental ; complications ; pathology ; Diabetes Mellitus, Type 1 ; complications ; pathology ; Diabetic Retinopathy ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Nitric Oxide Synthase Type III ; genetics ; Retinal Ganglion Cells ; pathology

Type 1 diabetes mellitus is caused by the autoimmune destruction of beta cells within the islets. In recent years, innate immunity has been proposed to play a key role in this process. High-mobility group box 1 (HMGB1), an inflammatory trigger in a number of autoimmune diseases, activates proinflammatory responses following its release from necrotic cells. Our aim was to determine the significance of HMGB1 in the natural history of diabetes in non-obese diabetic (NOD) mice. We observed that the rate of HMGB1 expression in the cytoplasm of islets was much greater in diabetic mice compared with non-diabetic mice. The majority of cells positively stained for toll-like receptor 4 (TLR4) were beta cells; few alpha cells were stained for TLR4. Thus, we examined the effects of anti-TLR4 antibodies on HMGB1 cell surface binding, which confirmed that HMGB1 interacts with TLR4 in isolated islets. Expression changes in HMGB1 and TLR4 were detected throughout the course of diabetes. Our findings indicate that TLR4 is the main receptor on beta cells and that HMGB1 may signal via TLR4 to selectively damage beta cells rather than alpha cells during the development of type 1 diabetes mellitus.
Animals ; Diabetes Mellitus, Type 1/immunology/*metabolism/pathology ; Female ; Gene Expression Regulation ; Glucagon-Secreting Cells/immunology/metabolism/pathology ; HMGB1 Protein/*genetics/metabolism ; Humans ; Immunity, Innate ; Insulin-Secreting Cells/immunology/metabolism/*pathology ; Macrophages/immunology/pathology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred NOD ; Necrosis ; Protein Binding ; Signal Transduction ; Toll-Like Receptor 4/*antagonists & inhibitors/genetics/immunology

Autoimmune diabetes is a T cell-mediated disease characterized by the autoimmune destruction of pancreatic β-cells and insulin deficiency. It is related to multiple genes. The IDDM1 locus, which lies within the human leukocyte antigen (HLA) and the IDDM2 locus, which is located to the insulin gene region, are two major genetic contributors of susceptibility. Many other loci conferring susceptibility to autoimmune diabetes are being discovered, including PTPN22, CTLA4, IL2RA and IFIH1. In this article, these loci and their possible immunologic mechanisms involved in the pathogenesis of this disease will be reviewed.
Animals ; Diabetes Mellitus, Type 1 ; genetics ; immunology ; pathology ; Genetic Predisposition to Disease ; Humans

The aim of this study is to investigate the therapeutic effect of RegIII-proinsulin-pBudCE4.1 plasmid on streptozotocin (STZ)-induced type 1 diabetes mellitus and its underlying mechanisms. The model of type 1 diabetes mellitus was established by intraperitoneal injections of STZ (40 mg kg(-1)) to Balb/c mice for five consecutive days. Then, ten type 1 diabetic mice were intramuscularly injected with 100 microg RegIII-proinsulin-pBudCE4.1 plasmid for 4 weeks (one time/week) and the blood glucose levels were monitored every week; whereas another ten diabetic mice served as negative control group were injected with pBudCE4.1 vector at the same dose. Normal control and model control mice were treated with normal saline at identical volume under the same way. Western blotting, MTT assay, ELISA, HE staining and Tunel assay were applied to explore the underlying mechanisms. Results showed that RegIII-proinsulin-pBudCE4.1 plasmid ameliorated the hyperglycemia symptoms in diabetic mouse remarkably. It induced an immunological tolerance state in type 1 diabetic mice by inhibiting the proliferation of splenic lymphocytes and recovering Th1/Th2 balance evidenced by MTT and ELISA analysis. Furthermore, it elevated insulin concentration in the serum of type 1 diabetic mice and promoted the regeneration of beta cells supported by the results of HE staining and Tunel assay. In conclusion, RegIII-proinsulin-pBudCE4.1 plasmid possesses powerful anti-diabetic ability, which may be involved in the inducing of immunological tolerance and enhancing beta cells recovery.
Animals ; Apoptosis ; Blood Glucose ; metabolism ; Cell Proliferation ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; therapy ; Diabetes Mellitus, Type 1 ; chemically induced ; metabolism ; pathology ; therapy ; Genetic Therapy ; Hyperglycemia ; therapy ; Injections, Intramuscular ; Insulin ; blood ; Islets of Langerhans ; cytology ; Male ; Mice ; Mice, Inbred BALB C ; Plasmids ; Proinsulin ; genetics ; metabolism ; therapeutic use ; Proteins ; genetics ; metabolism ; therapeutic use ; Streptozocin ; T-Lymphocytes ; cytology ; Th1-Th2 Balance

OBJECTIVETo study the effect of Astragalus polysaccharide (APS) on pancreatic beta cell mass in type 1 diabetic mice.

METHODDiabetic mice induced by multiple low dose streptozotocin (MLD-STZ) were administered either APS (100, 200, 400 mg x kg(-1) body weight) or saline intraperitoneally daily, and sacrificed after 15 or 30 days of treatment. Streptavidin-peroxidase immunohistochemical method with counterstain was performed to determine the effect of APS on insulitis. Indirect double immunofluorescence for Insulin/Ki67 (counterstained by Hoechst33258) and Insulin/Cleaved caspase-3 was used to evaluate pancreatic cell (besides beta cell) proliferation, beta cell neogenesis, beta cell apoptosis and beta cell mass. Semi-quantitative RT-PCR was utilized to characterize pancreatic regenerating protein 1 mRNA levels, and ELISA method was performed to measure the levels of cytokine IFN-gamma and IL-4 secreted by splenocytes.

RESULTAttenuated insulitis, upregulated beta cell mass, increased number of neogenetic pancreas islets, decreased number of apoptosis beta cells and downregulation of Th1/Th2 cytokine ratio were significantly time-and dose-dependent on APS treatment, when compared to saline controls. However, no significant differences of the number of pancreatic proliferative cells or replicative cells and pancreatic regenerating protein 1 mRNA levels were demonstrated between APS (APS100, APS200 and APS400) and saline vehicle group on day 15 and 30 with APS treatment.

CONCLUSIONAPS can upregulate pancreatic beta cell mass in type 1 diabetic mice, strongly associated with improved autoimmunity.

Animals ; Apoptosis ; drug effects ; Astragalus membranaceus ; chemistry ; Carrier Proteins ; metabolism ; Diabetes Mellitus, Experimental ; chemically induced ; metabolism ; pathology ; Diabetes Mellitus, Type 1 ; chemically induced ; metabolism ; pathology ; Enzyme-Linked Immunosorbent Assay ; Insulin-Secreting Cells ; drug effects ; metabolism ; pathology ; Interferon-gamma ; metabolism ; Interleukin-4 ; metabolism ; Islets of Langerhans ; drug effects ; metabolism ; pathology ; Lithostathine ; biosynthesis ; genetics ; Male ; Mice ; Mice, Inbred C57BL ; Plants, Medicinal ; chemistry ; Polysaccharides ; isolation & purification ; pharmacology ; RNA, Messenger ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Streptozocin ; Transcription Factors

OBJECTIVETo investigate the effect of losartan, an angiotensin II type-1 receptor (AT1R) antagonist, on the levels of angiotensin II (Ang II) and AT1R in diabetic rat kidney.

METHODSMale Wistar rats were divided into 3 groups, group A (n=11) served as the control group, group B (n=11) included the diabetic rats (induced by intraperitoneal injection of streptozotocin) without any therapy, and group C (n=9) diabetic rats treated with losartan. After 18 weeks of treatment, the kidneys were taken from all the rats to measure the expression of AT1R mRNA by RT-PCR and detect the Ang II level. Blood was also drawn from the heart to measure Ang II level, and 24-hour urine was collected to measure albumin level (urine albumin excretion, UAE) with rat albumin enzyme immunoassay kit.

RESULTSThe blood and renal Ang II levels showed no significant difference between the 3 groups. The expression of renal AT1R mRNA in group B (0.62-/+0.17) was significantly lower than that in group A (1.13-/+0.82, P<0.01) and group C (1.13-/+0.62,P<0.01). UAE in group B (2.18-/+1.98 mg) was significantly higher than that in group A (0.41-/+0.47 mg/d, P<0.01) and C (0.65 -/+0.89 mg/d, P<0.01).

CONCLUSIONLosartan can increase the expression of AT1R mRNA in diabetic rat kidneys without altering the blood and renal Ang II levels.

Angiotensin II ; blood ; metabolism ; Angiotensin II Type 1 Receptor Blockers ; therapeutic use ; Animals ; Diabetes Mellitus, Experimental ; blood ; drug therapy ; genetics ; Immunoassay ; methods ; Kidney ; drug effects ; metabolism ; pathology ; Losartan ; therapeutic use ; Male ; RNA, Messenger ; biosynthesis ; genetics ; Rats ; Rats, Wistar ; Receptor, Angiotensin, Type 1 ; genetics ; Reverse Transcriptase Polymerase Chain Reaction

Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Biphenyl Compounds ; pharmacology ; Creatinine ; metabolism ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Hypertrophy ; Immunohistochemistry ; Kidney ; metabolism ; pathology ; Male ; Matrix Metalloproteinase 2 ; analysis ; genetics ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Tetrazoles ; pharmacology ; Tissue Inhibitor of Metalloproteinase-2 ; analysis ; genetics