骨髓间充质干细胞胰腺内移植治疗糖尿病：是否发生了细胞的“转分化”？

摘要

BACKGROUND:In recent years a large number of studies have suggested that bone marrow mesenchymal stem cells can ease hyperglycemia of diabetic rats, but the related mechanism is unclear and controversial. OBJECTIVE:To investigate the relevant mechanism of bone marrow mesenchymal stem cells on pancreas microenvironment in vivo in diabetic rats. METHODS:Bone marrow mesenchymal stem cells were transfected with enhanced green fluorescent protein (EGFP) and administered to diabetic rats via the subcapsular pancreas. Blood glucose levels were monitored. The expressions of the key genes in islet development in these EGFP positive pancreatic cells were analyzed by Real-time quantitative PCR at different times. EGFP and insulin double-positive cells were detected by immunofluorescence. Flow cytometry was performed to analyze cellcycle and DNA ploidy. RESULTS AND CONCLUSION:Blood glucose levels were effectively reduced after transplantation. The expressions of the key genes in islet development reached their own peak values at different times after transplantation:Nestin at week 1, Nkx 2.2 at week 3, Pax 4 and Ngn 3 at week 4, insulin and glucagon at week 12, PDX-1 at week 8 until week 12. The cells double-positive for EGFP and insulin cells were observed. In the pancreas, EGFP positive cells at S+G 2/M phase were significantly increased, and there were no polyploid and aneuploid cells. In pancreas microenvironment, the bone marrow mesenchymal stem cells transplanted into the diabetic pancreas can differentiate into isletβ-like cells under gene control, but not through the fusion with tissue cells.%背景：近年来大量研究认为骨髓间充质干细胞植入后可以改善糖尿病鼠的高血糖状态，但相关的机制尚不明确且存在一些争议。目的：探讨骨髓间充质干细胞移植到糖尿病大鼠胰腺后的作用机制。方法：将增强型绿色荧光蛋白标记的骨髓间充质干细胞移植到糖尿病大鼠胰腺包膜下，血糖仪监测血糖， RT-PCR 动态检测受体鼠胰腺组织增强型绿色荧光蛋白阳性细胞中关键转录因子的表达，免疫荧光染色观察胰腺组织中增强型绿色荧光蛋白和胰岛素共表达情况，流式细胞术分析增强型绿色荧光蛋白阳性胰腺组织细胞的细胞周期和DNA倍性。结果与结论：胰腺包膜下移植骨髓间充质干细胞能有效降低糖尿病鼠血糖；Nestin、Nkx 2.2的表达分别在移植后1，3周到达峰值，Pax 4和Ngn 3的表达在移植后4周到达峰值，胰岛素和胰高血糖素的表达至移植后12周到达峰值，PDX-1的表达在8周时达到峰值并维持至12周；免疫荧光染色发现有增强型绿色荧光蛋白和胰岛素共表达细胞；流式细胞术测定增强型绿色荧光蛋白阳性的胰腺组织细胞中处于S+G2/M期的细胞增加，细胞核型未见多倍体或非整倍体细胞。提示在胰腺微环境中，植入糖尿病鼠胰腺局部的骨髓间充质干细胞在基因调控下向胰岛β样细胞发生横向转分化，而非细胞融合获得β细胞的功能表型。