Identification and differentiation of PDX1 β-cell progenitors within the human pancreatic epithelium

AIM:To minimize the expansion of pancreatic mesenchymal cells in vitro and confirm thatβ-cell progenitors reside within the pancreatic epithelium.METHODS:Due to mesenchymal stem cell(MSC)expansion and overgrowth,progenitor cells within the pancreatic epithelium cannot be characterized in vitro,thoughβ-cell dedifferentiation and expansion of MSC intermediates via epithelial-mesenchymal transition(EMT)may generateβ-cell progenitors.Pancreatic epithelial cells from endocrine and non-endocrine tissue were expanded and differentiated in a novel pancreatic epithelial expansion medium supplemented with growth factors known to support epithelial cell growth(dexamethasone,epidermal growth factor,3,5,3’-triiodo-l-thyronine,bovine brain extract).Cells were also infected with a single and dual lentiviral reporter prior to cell differentiation.Enhanced green fluorescent protein was controlled by the rat Insulin 1 promoter and the monomeric red fluorescent protein was controlled by the mouse PDX1 promoter.In combination with lentiviral tracing,cells expanded and differentiated in the pancreatic medium were characterized by flow cytometry(BD fluorescence activated cell sorting),immunostaining and real-time polymerase chain reaction(PCR)(7900HT Fast Realtime PCR System).RESULTS:In the presence of 10%serum MSCs rapidly expand in vitro while the epithelial cell population declines.The percentage of vimentin+cells increased from 22%±5.83%to 80.43%±3.24%(14 d)and99.00%±0.0%(21 d),and the percentage of epithelial cells decreased from 74.71%±8.34%to 26.57%±9.75%(14 d)and 4.00%±1.53%(21 d),P<0.01 for all time points.Our novel pancreatic epithelial expansion medium preserved the epithelial cell phenotype and minimized epithelial cell dedifferentiation and EMT.Cells expanded in our epithelial medium contained significantly less mesenchymal cells(vimentin+)compared to controls(44.87%±4.93%vs 95.67%±1.36%;P<0.01).During cell differentiation lentiviral reporting demonstrated that,PDX1+and insulin+cells were localized within adherent epithelial cell aggregates compared to controls.Compared to starting islets differentiated cells had at least two fold higher gene expression of PDX1,insulin,PAX4 and RFX(P<0.05).CONCLUSION:PDX1+cells were confined to adherent epithelial cell aggregates and not vimentin+cells(mesenchymal),suggesting that EMT is not a mechanism for generating pancreatic progenitor cells.

Bioengineered stem cells as an alternative for islet cell transplantation

Type 1 diabetes is an autoimmune and increasingly prevalent condition caused by immunological destruction of beta cells. Insulin remains the mainstay of therapy. Endeavours in islet transplantation have clearly demonstrated that type 1 diabetes is treatable by cellular replacement. Many challenges remain with this approach. The opportunity to use bioengineered embryonic or adult pluripotential stem cells, or islets derived from porcine xenograft sources could address future demands, but are still associated with considerable challenges. This detailed review outlines current progress in clinical islet transplantation, and places this in perspective for the remarkable scientific advances now occurring in stem cell and regenerative medicine approaches in the treatment of future curative treatment of diabetes.

Protective effects of cyclosporine and its analog NIM-811 in a murine model of hepatic ischemia-reperfusion injury

Background and aim:The liver is susceptible to ischemia-reperfusion injury(IRI)during hepatic surgery,when the vessels are compressed to control bleeding,or liver transplantation,when there is an obligate period of ischemia.The hallmark of IRI comprises mitochondrial dysfunction,which generates reactive oxygen species,and cell death through necrosis or apoptosis.Cyclosporine(CsA),which is a well-known immunosuppressive agent that inhibits calcineurin,has the additional effect of inhibiting the mito-chondrial permeability transition pore(mPTP),thereby,preventing mitochondrial swelling and injury.NIM-811,which is the nonimmunosuppressive analog of CsA,has a similar effect on the mPTP.In this study,we tested the effect of both agents on mitigating warm hepatic IRI in a murine model.Materials and methods:Before ischemic insult,the mice were administered with intraperitoneal normal saline(control);CsA at 2.5,10,or 25 mg/kg;or NIM-811 at 10 mg/kg.Thereafter,the mice were subjected to partial warm hepatic ischemia by selective pedicle clamping for 60 min,followed by 6 h of recovery after reperfusion.Serum alanine transaminase(ALT)was measured,and the liver tissue was examined histologically for the presence of apoptosis and the levels of inflammatory cytokines.Results:Compared with the control mice,the mice treated with 10 and 25 mg/kg of CsA and NIM-811 had significantly lower ALT levels(P<0.001,0.007,and 0.031,respectively).Moreover,the liver tissue showed reduced histological injury scores after treatment with CsA at 2.5,10,and 25 mg/kg and NIM-811(P=0.041,<0.001,0.003,and 0.043,respectively)and significant decrease in apoptosis after treatment with CsA at all doses(P=0.012,0.007,and<0.001,respectively).Levels of the pro-inflammatory cyto-kines,particularly interleukin(IL)-1β,IL-2,IL-4,IL-10,and keratinocyte chemoattractant/human growth-regulated oncogene significantly decreased in the mice treated with the highest dose of CsA(25 mg/kg)than those in the control mice.Conclusions:Premedication with CsA or NIM-811 mitigated hepatic IRI in mice,as evidenced by the decreased ALT and reduced injury on histology.These results have potential implications on mitigating IRI during liver transplantation and resection.

索马鲁肽对2型糖尿病患者的心血管益处非劣效于安慰剂

背景索马鲁肽是一种正在开发中的胰高血糖素样肽1（GLP-1）类似物，用于治疗2型糖尿病。其在分子结构上与利拉鲁肽相似，但具有更长的半衰期，仅需每周使用1次。美国食品与药品监督管理局（FDA）的监管指导要求提供相关证据，即2型糖尿病新疗法不可将患者的心血管风险增高太多。这些证据定义为：相关药物对于安慰剂的估计风险比的95％可信区间（CI）的上限为1-3；这个数字的初始值在上市前阶段其界值可达1．8；而如果上市前这个数字达不到1.3，那么上市后需要进行随机安全性临床试验。