We assessed the number of vessels found per area of each transplanted islet. 3,960 min*mg/dl, NGF-treated; 47,900 3,220 min*mg/dl: *p = 0.0348). NGF treatment of islets was also associated with increased graft failure [the percentage of TdT-mediated dUTP-biotin nick-end labeling (TUNEL)-positive and necrotic transplanted islets on POD 5, control; 23.8% (5/21), NGF-treated; 52.9% (9/17): p = 0.0650] following intraportal islet transplantation. Nonviable (TUNEL-positive and necrotic) islets in both groups expressed vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 (HIF-1). On the other hand, viable (TUNEL-negative and not necrotic) islets in both groups did not express VEGF and HIF-1. In the present study, pre-transplant NGF treatment was associated with impaired survival and angiogenesis of intraportal islet grafts. The effect of NGF on islet transplantation may significantly vary according to the transplant site. Keywords:Apoptosis, diabetes, intraportal, islet transplantation, nerve growth factor == Introduction == Islet transplantation has become a valuable therapy for type 1 diabetes mellitus. Although the Edmonton protocol introduced Dinoprost tromethamine various suggestions for the improvement of islet transplantation,1there is a concern of deteriorating graft function over time.2In addition, while single-donor islet transplantation success has been achieved,3-5most centers still rely on multiple donor organs to achieve initial insulin independence. 6A possible explanation for this problem is that many islets are destroyed immediately following transplantation, before a vascular network is re-established.7-12Although native islets in Dinoprost tromethamine the pancreas have a rich microvasculature, islet blood vessels are disrupted during islet isolation. Proper revascularization of the transplanted islets is of great importance for the function and survival of islet grafts. Nerve growth factor (NGF), which is well known as a neurotrophic factor,13,14has recently been recognized as an angiogenic factor in several tissues15-18and is reported to play an important regulatory role in pancreatic -cell function.19-22We previously demonstrated that treatment of pancreatic islets with NGF improved their quality and viability. Revascularization and survival of islets transplanted under the kidney capsule were improved by NGF.20Moreover, islets were efficiently transplanted in vascularized chambers based on the neurovascular support from the femoral artery, vein and nerve, in the presence of a gelatin sponge scaffold with NGF.23However, the usefulness of NGF in intraportal islet transplantation was still unknown. To resolve this problem, we transplanted syngeneic islets (360 islet equivalents per recipient) cultured with or without 2.5S mouse NGF for 24 h into the portal vein of streptozotocin-induced diabetic BALB/c mice. == Results == == Islet viability and function test in vitro == At 24 h after culture, islet viability was improved by NGF treatment in a dose-dependent manner (control; 84.0 2.41%, NGF 20 ng/mL; 86.5 2.51%, NGF 100 ng/mL; 91.7 1.55%*, NGF 500 ng/mL; 95.5 0.852%**: *p < 0.05, **p < 0.01 vs. control, ANOVA p = 1.06 105) (Fig. 1A). However, there were Dinoprost tromethamine Dinoprost tromethamine no significant differences between these groups in terms of islet function (Stimulation Index, control; 1.78 0.345, NGF 20 ng/mL; 1.92 0.347, NGF 100 ng/mL; 1.72 0.203, NGF 500 ng/mL; 1.45 0.279: ANOVA p = 0.735) (Fig. 1B). Figure 1.Effect of NGF treatment for 24 h in culture on in vitro islet viability and function test. (A) Islet viability was tested by fluorescence microscopy using SYTO green (green for viable area) and ethidium bromide (red for dead area). The ratio of the green area relative to total stained (green + red) area was calculated. It was improved by Rabbit Polyclonal to C-RAF (phospho-Ser621) NGF treatment in a dose-dependent manner (control; 84.0 2.41%, NGF 20 ng/mL; 86.5 2.51%, NGF 100 ng/mL; 91.7 1.55%*, NGF 500 ng/mL; 95.5 0.852%**: *p < 0.05, **p < 0.01 vs. NGF 0 ng/mL, ANOVA p = 1.06 105)..