体内回输骨髓干细胞对链脲佐菌素诱导糖尿病小鼠作用的初步研究

A preliminary study on recruitment of the bone marrow-derived stem cells into streptozotocin-induced diabetic mice

目的探讨回输至链脲佐菌素（STZ）诱导的糖尿病小鼠体内的骨髓干细胞能否在体内被诱导分化为胰岛素阳性细胞。方法将实验小鼠分为3组，即正常组、对照组（糖尿病组）和实验组（糖尿病并接受骨髓干细胞回输组）。待回输的骨髓干细胞取白3周龄雄性Balb／c小鼠，按改良的Verfaillie实验室的培养条件分离培养骨髓干细胞。STZ诱导的6～8周龄雌性Balb／c糖尿病小鼠为回输骨髓干细胞的受者。实验组小鼠尾静脉注射1～2×10%6 CFSE标记的骨髓干细胞。观察各组小鼠血糖、体重变化。4周后实验结束时，取胰腺行Y染色体PCR扩增、胰岛素免疫荧光和CFSE检测，了解骨髓干细胞在胰腺的定位及诱导分化情况；计算、比较3组胰岛素免疫组化切片中胰腺组织胰岛面积和胰岛素阳性面积，了解体内回输骨髓干细胞能否诱导分化为胰岛素阳性细胞。结果实验过程中，实验组和对照组小鼠的血糖无明显下降，体重无明显增加，而正常组血糖保持在正常范围，体重逐渐增加；实验组中，胰腺组织Y染色体（n=6）的检出比例为6／6（100％）；实验组小鼠胰腺组织有CFSE标记细胞检出，每视野下胰岛素染色阳性同时CFSE染色阳性细胞数为1．2±1．1；胰岛面积，实验组为（10172±6303）μm^2，对照组为（9857±4444）μm^2，正常组为（17175±10495）μm^2。实验组与对照组比较，差异无统计学意义；与正常组比较，实验组和对照组显著小于正常组（均P〈0．05）；胰岛素染色面积，实验组为（474±380）μm^2。对照组为（329±499）μm^2，正常组为（1527±1788）μm^2；实验组大于对照组（P〈0．05），小于正常组（P〈0．05）。结论在STZ诱导的糖尿病小鼠回输骨髓干细胞，有少部分可定位于胰腺，具备胰岛素阳性细胞的特征。

Objective To investigate whether the versatile bone marrow-derived stem cells could be transdifferentiated into insulin-positive cells in streptozotocin （STZ）-induced diabetic mice. Methods Cells were cultured under the conditions referred by Verfaillie method with some modification. Female Balb/c mice （6-8- week-old） were used as recipients, while male mice （3-week-old） as donors. Diabetic mice induced by STZ received 1-2 × 10^6carboxyflurescein diacetate succinmidyl ester （CFSE, a kind of fluorescent label）-labeled cells via tail vein injection. At the end of 4-week test, chromosome Y in the female mice was determined by PCR and Cy3 labeled insulin and CFSE staining were observed under fluorenseent microscope. Pancreas were harvested for insulin immtmochemistry and both islet and insulin positive area were calculated. Results There were no significant changes of beth blood glucose and body weight in test group and control group before and at the end of 4- weeks test, but normal blood glucose and increased body weight were found in the normal group. Chromosome Y was detected in all of the female mice with bone marrow-derived stem cell transplantation. Cells double stained with CFSE and insulin were found in pancreas with the number per section being 1.2 ± 1.1. Insulin immunochemistry found that the islet neogenesis with the insulin-positive area was higher in these mice compared with those without transplantation [ （474 ± 380 vs 329 ± 499）μm^2, P = 0. 037 ], while there was no significant difference of islet area between them （ 10 172 ± 6 303 ）μm^2 vs （9 857 ± 4 444）μm^2. The islet and insulin area of the normal group [ （ 17 175 ± 10 495 ）μm^2 and （ 1 527 ± 1 788 ） μm^2, respectively ] were higher than those in test and control group. Conclusion The transplanted bone marrow-derived stem cells could reside at the pancreatic site of STZ- induced diabetic mice and be transdifferantiated into insulin-positive cells.