Type 1 diabetes mellitus (T1D) is characterized by the autoimmune destruction of the pancreatic β cells. The transplantation of mesenchymal stromal/stem cells (MSC) was reported to rescue the damaged pancreatic niche. However, there is an ongoing discussion on whether direct physical contact between MSC and pancreatic islets results in a superior outcome as opposed to indirect effects of soluble factors released from the MSC entrapped in the lung microvasculature after systemic administration. Hence, MSC were studied in direct contact (DC) and indirect contact (IDC) with murine pancreatic β cell line MIN6-cells damaged by nitrosourea derivative streptozotocin (STZ) in vitro. Further, the protective and antidiabetic outcome of MSC transplantation was evaluated through the intrapancreatic route (IPR) and intravenous route (IVR) in STZ-induced diabetic NMRI nude mice. MSC were investigated in culture with STZ-damaged MIN6-cells, either under direct contact (DC) or separated through a semi-permeable membrane (IDC). Moreover, multiple low doses of STZ were administered to NMRI nude mice for the induction of hyperglycemia. 0.5 × 106 adipose-derived mesenchymal stem cells (ADMSC) were transferred through direct injection into the pancreas (IPR) or the tail vein (IVR), respectively. Bromodeoxyuridine (BrdU) was injected for the detection of proliferating islet cells in vivo, and real-time polymerase chain reaction (RT-PCR) was employed for the measurement of the expression of growth factor and immunomodulatory genes in the murine pancreas and human MSC. Phosphorylation of AKT and ERK was analyzed with Western blotting. The administration of MSC through IPR ameliorated hyperglycemia in contrast to IVR, STZ, and non-diabetic control in a 30-day window. IPR resulted in a higher number of replicating islet cells, number of islets, islet area, growth factor (EGF), and balancing of the Th1/Th2 response in vivo. Physical contact also provided a superior protection to MIN6-cells from STZ through the AKT and ERK pathway in vitro in comparison with IDC. Our study suggests that the physical contact between MSC and pancreatic islet cells is required to fully unfold their protective potential.

中文翻译：

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胰内MSC移植促进胰岛再生

1型糖尿病（T1D）的特征是胰腺β细胞的自身免疫破坏。据报道，间质基质/干细胞（MSC）的移植可挽救受损的胰腺小生境。但是，与全身性给药后，由包裹在肺微脉管系统中的MSC释放的可溶性因子的间接作用相反，关于MSC与胰岛之间的直接物理接触是否会产生更好的结果仍在进行中。因此，在体外研究了与亚硝基脲衍生物链脲佐菌素（STZ）损伤的小鼠胰腺β细胞系MIN6-细胞的直接接触（DC）和间接接触（IDC）。进一步，通过STZ诱导的糖尿病NMRI裸鼠的胰内途径（IPR）和静脉途径（IVR）评估了MSC移植的保护性和抗糖尿病性。在直接接触（DC）或通过半透膜（IDC）分离的STZ损伤的MIN6-细胞培养中研究了MSC。此外，将多种低剂量的STZ施用于NMRI裸鼠以诱导高血糖症。通过直接注射分别将0.5×106的脂肪间充质干细胞（ADMSC）转移到胰腺（IPR）或尾静脉（IVR）中。注射了溴脱氧尿苷（BrdU），用于检测体内增殖的胰岛细胞，实时聚合酶链反应（RT-PCR）用于检测鼠胰腺和人MSC中生长因子和免疫调节基因的表达。用Western印迹分析AKT和ERK的磷酸化。与IPR，STZ和30天非糖尿病对照组相比，通过IPR施用MSC改善了高血糖。IPR导致体内复制胰岛细胞数量增加，胰岛数量增加，胰岛面积增加，生长因子（EGF）以及Th1 / Th2反应的平衡。与IDC相比，体外物理接触还通过AKT和ERK途径为STZ的MIN6-细胞提供了出色的保护。我们的研究表明，MSC与胰岛细胞之间的物理接触是充分发挥其保护潜力所必需的。用Western印迹分析AKT和ERK的磷酸化。与IPR，STZ和30天非糖尿病对照组相比，通过IPR施用MSC改善了高血糖。IPR导致体内复制胰岛细胞数量增加，胰岛数量增加，胰岛面积增加，生长因子（EGF）以及Th1 / Th2反应的平衡。与IDC相比，体外物理接触还通过AKT和ERK途径为STZ的MIN6-细胞提供了出色的保护。我们的研究表明，MSC与胰岛细胞之间的物理接触是充分发挥其保护潜力所必需的。用Western印迹分析AKT和ERK的磷酸化。与IPR，STZ和30天非糖尿病对照组相比，通过IPR施用MSC改善了高血糖。IPR导致体内复制胰岛细胞数量增加，胰岛数量增加，胰岛面积增加，生长因子（EGF）以及Th1 / Th2反应的平衡。与IDC相比，体外物理接触还通过AKT和ERK途径为STZ的MIN6-细胞提供了出色的保护。我们的研究表明，MSC与胰岛细胞之间的物理接触是充分发挥其保护潜力所必需的。IPR导致体内复制胰岛细胞数量增加，胰岛数量增加，胰岛面积增加，生长因子（EGF）以及Th1 / Th2反应的平衡。与IDC相比，体外物理接触还通过AKT和ERK途径为STZ的MIN6-细胞提供了出色的保护。我们的研究表明，MSC与胰岛细胞之间的物理接触是充分发挥其保护潜力所必需的。IPR导致体内复制胰岛细胞数量增加，胰岛数量增加，胰岛面积增加，生长因子（EGF）以及Th1 / Th2反应的平衡。与IDC相比，体外物理接触还通过AKT和ERK途径为STZ的MIN6-细胞提供了出色的保护。我们的研究表明，MSC与胰岛细胞之间的物理接触是充分发挥其保护潜力所必需的。