Stem cell therapies for Type 1 diabetes: current status and proposed road map to guide successful clinical trials.

Many people with Type 1 diabetes struggle with the burden of self-management and are unable to achieve optimal glycaemic control without risk of hypoglycaemia. Future therapies with the potential to reduce the risk for short- and long-term complications while simultaneously reducing the burden of diabetes are therefore attractive. ß-cell replacement is one strategy which might achieve this. Islet transplantation is limited by organ supply and the risks of long-term immunosuppression. Encapsulated stem-cell-derived ß cells have the potential to address both of these issues and phase I/II clinical trials of encapsulated pancreatic progenitors have begun. A significant risk associated with the translation of stem-cell science to the clinical management of Type 1 diabetes is an underestimation of the complexity of the process and a mismatch between the hype and the expectations of both people with Type 1 diabetes and the public. We provide an update on progress in clinical trials of encapsulated stem-cell-derived ß cells and propose a road map for the design and conduct of future trials to facilitate the translation of this exciting science to clinical care.

Blocking the VISTA pathway enhances disease progression in (NZB × NZW) F1 female mice.

V-domain Ig suppressor of T-cell activation (VISTA) is a critical negative checkpoint molecule involved in regulating the immune response. Targeting the pathway with an antagonist anti-VISTA antibody designated 13F3 has been shown to enhance disease severity in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. To determine if VISTA plays a role in murine lupus, New Zealand Black × New Zealand White (BWF1) mice were treated with 13F3 or control hamster Ig and disease monitored. Onset of proteinuria was earlier and renal damage more profound in mice treated with 13F3. Cell subset analysis showed an increase of activated splenic T cells and inflammatory splenic myeloid cells, but no effect on B cells, in mice receiving 13F3. Examination of the kidney showed an increase in inflammatory myeloid cell infiltration with 13F3 treatment. This study along with previous EAE data, suggests that interventions that enhance VISTA regulatory activity may be effective for the treatment of autoimmune disease.

Effect of ranolazine on glycaemic control in patients with type 2 diabetes treated with either glimepiride or metformin.

AIM: To report the results of two phase III trials assessing the efficacy of ranolazine for glycaemic control in patients with type 2 diabetes on metformin or glimepiride background therapy. METHODS: In two double-blind trials we randomized 431 and 442 patients with type 2 diabetes to ranolazine 1000 mg twice daily versus placebo added to either glimepiride (glimepiride add-on study) or metformin background therapy (metformin add-on study). Patients receiving ranolazine added to metformin had their metformin dose halved (with the addition of a metformin-matched placebo) relative to the placebo group to correct for a metformin-ranolazine pharmacokinetic interaction. The primary endpoint of the trials was the change from baseline in glycated haemoglobin (HbA1c) at week 24. RESULTS: When added to glimepiride, ranolazine caused a 0.51% least squares mean [95% confidence interval (CI) 0.71, 0.32] decrease from baseline in HbA1c at 24 weeks relative to placebo and roughly doubled the proportion of patients achieving an HbA1c of <7% (27.1 vs 14.1%; p = 0.001). When added to metformin background therapy, there was no significant difference in the 24-week HbA1c change from baseline [placebo-corrected LS mean difference -0.11% (95% CI -0.31, 0.1)]. CONCLUSIONS: Compared with placebo, addition of ranolazine in patients with type 2 diabetes treated with glimepiride, but not metformin, significantly reduced HbA1c over 24 weeks. The decreased dose of metformin used in the metformin add-on study complicates the interpretation of this trial. Whether an effective regimen of ranolazine added to metformin for glycaemic control can be identified remains unclear.

Reduced peripheral activity leading to hepato-preferential action of basal insulin peglispro compared with insulin glargine in patients with type 1 diabetes.

AIMS: Basal insulin peglispro (BIL), a novel PEGylated basal insulin with a large hydrodynamic size, has a delayed absorption and reduced clearance that prolongs the duration of action. The current study compared the effects of BIL and insulin glargine (GL) on endogenous glucose production (EGP), glucose disposal rate (GDR) and lipolysis in patients with type 1 diabetes. MATERIALS AND METHODS: This was a randomized, open-label, four-period, crossover study. Patients received intravenous infusions of BIL and GL, each at two dose levels selected for partial and maximal suppression of EGP, during an 8 to 10 h euglycemic clamp procedure with d-[3-3 H] glucose. RESULTS: Following correction for equivalent human insulin concentrations (EHIC), low-dose GL infusion resulted in similar EGP at the end of the clamp compared to low-dose BIL infusion (GL/BIL ratio of 1.03) but a higher GDR (GL/BIL ratio of 2.42), indicating similar hepatic activity but attenuated peripheral activity of BIL. Consistent with this, the EHIC-corrected GDR/EGP at the end of the clamp was 1.72-fold greater for GL than BIL following low-dose administration. At the lower dose of BIL and GL (concentrations in the therapeutic range), BIL produced less suppression of lipolysis compared with GL as indicated by free fatty acid and glycerol levels at the end of the clamp. CONCLUSIONS: Compared with GL, BIL restored the hepato-peripheral insulin action gradient seen in normal physiology via its peripherally restricted action on target tissues related to carbohydrate and lipid metabolism.

Morning administration of 0.4U/kg/day insulin glargine 300U/mL provides less fluctuating 24-hour pharmacodynamics and more even pharmacokinetic profiles compared with insulin degludec 100U/mL in type 1 diabetes.

AIM: To compare steady state pharmacodynamic and pharmacokinetic profiles of insulin glargine 300U/mL (Gla-300) with insulin degludec 100U/mL (Deg-100) in people with type 1 diabetes. METHODS: This single-centre, randomized, double-blind crossover euglycaemic clamp study included two parallel cohorts with fixed once-daily morning dose regimens. For both insulins participants received 0.4 (n=24) or 0.6U/kg/day (n=24), before breakfast, for 8 days prior to the clamp. The main endpoint was within-day variability (fluctuation) of the smoothed glucose infusion rate (GIR) over 24 hours (GIR-smFL0-24). RESULTS: Gla-300 provided 20% less fluctuation of steady state glucose infusion rate profiles than Deg-100 over 24 hours at 0.4U/kg/day (GIR-smFL0-24 treatment ratio 0.80 [90% confidence interval: 0.66 to 0.96], P=0.047), while at the dose of 0.6U/kg/day the difference between insulins was not statistically significant (treatment ratio 0.96 [0.83 to 1.11], P=0.603). Serum insulin concentrations appeared more evenly distributed with both dose levels of Gla-300 versus the same doses of Deg-100, as assessed by relative 6-hour fractions of the area under the curve within 24 hours. Both insulins provided exposure and activity until 30 hours (end of clamp). CONCLUSION: Gla-300 provides less fluctuating steady state pharmacodynamic profiles (i.e. lower within-day variability) and more evenly distributed pharmacokinetic profiles, compared with Deg-100 in a once-daily morning dosing regimen of 0.4U/kg/day.

Genetic characterization of small ovaries, a gene required in the soma for the development of the Drosophila ovary and the female germline.

The small ovary gene (sov) is required for the development of the Drosophila ovary. Six EMS-induced recessive alleles have been identified. Hypomorphic alleles are female sterile and have no effect on male fertility, whereas more severe mutations result in lethality. The female-sterile alleles produce a range of mutant phenotypes that affect the differentiation of both somatic and germline tissues. These mutations generally produce small ovaries that contain few egg cysts and disorganized ovarioles, and in the most extreme case no ovarian tissue is present. The mutant egg cysts that develop have aberrant morphology, including abnormal numbers of nurse cells and patches of necrotic cells. We demonstrate that sov gene expression is not required in the germline for the development of functional egg cysts. This indicates that the sov function is somatic dependent. We present evidence using loss-of-function and constitutive forms of the somatic sex regulatory genes that sov activity is essential for the development of the somatic ovary regardless of the chromosomal sex of the fly. In addition, the genetic mapping of the sov locus is presented, including the characterization of two lethal sov alleles and complementation mapping with existing rearrangements.

Regulatory and functional interactions between ovarian tumor and ovo during Drosophila oogenesis.

The ovo and ovarian tumor genes are required during early and late stages of Drosophila oogenesis. The ovo product, a zinc-finger transcription factor, can bind to sites and influence the level of expression of the ovarian tumor promoter. Our examination of ovo null mutant organelles demonstrate that it is required for the differentiation of XX germ cells during larval gonial stages, in addition to its known role in maintaining germ cell numbers. In contrast, ovarian tumor is required during pupal and adult stages for the cystocyte divisions that give rise to the egg chamber. Studies on sexually transformed flies indicate that both the ovo and ovarian tumor null mutant phenotypes are distinctive from and more severe than the germline defects produced when male germ cells develop in female soma. This suggests that ovo and ovarian tumor have oogenic functions other than their putative role in germline sex determination. We also demonstrate that the regulation of ovarian tumor by ovo is stage-specific, as ovarian tumor promoter activity does not require ovo during larval stages but becomes ovo-dependent in the adult ovary. This coincides with when the ovarian tumor promoter becomes responsive to sex-specific signals from the soma suggesting a convergence of somatic and germline regulatory pathways on ovarian tumor during oogenesis.

The Drosophila ovarian tumor gene is required for the organization of actin filaments during multiple stages in oogenesis.

The ovarian tumor gene is required during both early and late stages of oogenesis. Mutations produce a range of phenotypes, including agametic ovarioles, tumorous egg chambers, and late stage oogenic arrest. We demonstrate that each of these phenotypes is associated with specific aberrations in actin distribution. In the earliest case, ovarian tumor mutations cause actin filaments to accumulate ectopically in the fusome. This correlates with abnormal fusome morphology and arrested germ cell development in the germaria. Similarly, ovarian tumor function is required for the localization of actin that is essential for the maturation of ring canals. This defect gives rise to tumorous egg chambers in which germ cell numbers and morphology are profoundly aberrant. We also confirm that ovarian tumor is required for the formation of the nurse cell cytoplasmic actin array that is essential for the nonspecific transport of cytoplasmic contents to the oocyte during late oogenesis. Our data suggest that at this stage ovarian tumor controls the site where actin filaments initiate. Taken together, these studies suggest that the diverse ovarian tumor mutant phenotypes derive from the mislocalization of actin filaments, indicating a role for this gene in organizing the female germline cytoskeleton, and that the misregulation of actin can have profound effects on germ cell division and differentiation.