Prevention of diabetes in BB/Wor rats by intrathymic islet injection

The objective of this study was to determine whether the intrathymic injection of islets can prevent the development of diabetes in BB/Wor rats. Evidence suggests that a failure to induce islet thymic tolerance may be an etiological factor in the development of the disease. It was theorized that the introduction of islets into the thymus might directly induce islet tolerance and thus prevent disease. Islets from diabetes-resistant BB/Wor rats were injected into the thymuses of 23 young diabetes-prone BB/Wor rats; 25 sham-operated animals served as controls. Results showed that 22 of the 25 control rats became diabetic while only 8 of the 23 experimental rats became diabetic (P less than 0.0002). The specific lysis of islet cells by spleen cells from nondiabetic experimental and control rats was comparable and less than the lysis induced by spleen cells from diabetic rats. These data demonstrate that the intrathymic injection of islets into diabetes-prone BB/Wor rats is an effective method for preventing the development of autoimmune type I diabetes

Effects of topical insulin administration on phosphorylated protein kinase B and nitric oxide levels in the rat retina

Purpose: To examine the effects of insulin treatment on the expression of phosphorylated protein kinase B (Akt or pAkt) and nitric oxide (NO), known targets of insulin action. Methods: Retinas from Lewis rats were treated with insulin in vitro, and the levels of pAkt and NO expression assessed in lysed tissue homogenates at various time points. In addition, rats were treated in vivo with a single eye drop containing 1% insulin after which the levels of pAkt and NO were assessed in their retinas at various time points. Results: Incubation of retinas in media containing 10 or 100 ng/mL of insulin resulted in a significant increase in their expression of pAkt 15–30 min later. When insulin was topically applied in vivo, its levels peaked in the retina 35 min. Topically applied insulin significantly increased retinal pAkt levels 10 and 15 min post-treatment (p < 0.02 and 0.01, respectively). NO levels were elevated 20 min after insulin treatment both in vitro and in vivo (p < 0.007 and 0.04, respectively). Conclusions: Insulin upregulated retinal expression of pAkt and NO both in vivo and in vitro, suggesting that topically applied insulin that accumulates in the retina may be physiologically active

Effects of topical insulin administration on phosphorylated protein kinase B and nitric oxide levels in the rat retina

AbstractPurposeTo examine the effects of insulin treatment on the expression of phosphorylated protein kinase B (Akt or pAkt) and nitric oxide (NO), known targets of insulin action.MethodsRetinas from Lewis rats were treated with insulin in vitro, and the levels of pAkt and NO expression assessed in lysed tissue homogenates at various time points. In addition, rats were treated in vivo with a single eye drop containing 1% insulin after which the levels of pAkt and NO were assessed in their retinas at various time points.ResultsIncubation of retinas in media containing 10 or 100ng/mL of insulin resulted in a significant increase in their expression of pAkt 15–30min later. When insulin was topically applied in vivo, its levels peaked in the retina 35min. Topically applied insulin significantly increased retinal pAkt levels 10 and 15min post-treatment (p<0.02 and 0.01, respectively). NO levels were elevated 20min after insulin treatment both in vitro and in vivo (p<0.007 and 0.04, respectively).ConclusionsInsulin upregulated retinal expression of pAkt and NO both in vivo and in vitro, suggesting that topically applied insulin that accumulates in the retina may be physiologically active

Abstract 344: Cardiac Grafts Engineered From Human Induced Pluripotent Stem Cell Ventricular Pure or Heterogeneous Cardiomyocytes Display Synchronous and Spontaneous Contraction and Reduce Ventricular Tachycardia in Rats with Chronic Heart Failure

Background: Twenty six million people worldwide are diagnosed with chronic heart failure (CHF). With only 5000 heart transplants performed annually, the prognosis for the remaining individuals is poor and new therapeutic options are needed. Previously we have described a cardiac engineered graft comprised of human induced pluripotent stem cell (iPSC) derived cardiomyocytes co-cultured with fibroblasts in a bio-absorbable mesh. Few studies to date have examined comparatively the therapeutic benefits of different cardiac populations. In the present study we engineered grafts generated with either hiPSC derived heterogeneous cardiac myocytes (hetCMs) or ventricular pure myocyte (VMs) populations to compare functional outcomes in a rat model of CHF. Methods: Cardiac grafts were generated with hetCMs or VMs (Axiogenesis) by co-culture into a 3D bioabsorbable mesh with human dermal fibroblasts. The hetCMs contain 60% ventricular, 40% atrial and nodal-like cardiomyocytes. The VMs contain 90% ventricular and 10% atrial cardiomyocytes. Grafts were evaluated in culture out to 6 days. Adult male Sprague-Dawley rats underwent permanent left coronary artery ligation and were randomized to Sham, CHF or graft treatment. Hemodynamic pressure measurements were performed at 6 weeks post-ligation with Millar solid state micromanometer pressure catheters. Ventricular tachycardia (VT) induction studies were performed at study endpoint (3 weeks after implant) to evaluate VT susceptibility using methods developed in the laboratory. Results: Both HetCM and VM generated cardiac grafts displayed synchronous and spontaneous contractions after 48hrs in culture and maintained an average contraction rate of 67±6 (hetCM) and 71±9 (VM) beats per minute (n=10 per group). Implantation of HetCM and VM grafts lowered (p&lt;0.05) EDP 45% and 14% (n=10) and resulted in decreased susceptibility of VT induction 54% and 65%, respectively (n=4). Conclusion: Cardiac grafts engineered with hetCMs or VMs and implanted in a rat CHF model can lower LV EDP in-vivo while decreasing susceptibility of induced VT. This approach raises the possibility that iPSC derived engineered grafts may be used as a treatment for VT in patients with CHF. </jats:p