绿色荧光蛋白转基因小鼠不同源性间充质干细胞原代培养及生物学特性比较

 目的： 探讨绿色荧光蛋白转基因小鼠脐带和骨髓源性间充质干细胞 （MSCs）的体外分离培养方法、生物学特性、表面标志及多向分化潜能。方法：应用Ⅱ型胶原酶消化培养法分离脐带MSCs及密度梯度离心法分离骨髓MSCs进行体外培养。在倒置显微镜下观察2种细胞的生长特点，运用生长曲线和MTT法检测其原代细胞增殖能力，台盼蓝法测定细胞传代成活率，采用流式细胞术测定2种第3代（P3）细胞DNA周期及表面标志物的表达，并比较其向成脂细胞和成骨细胞的分化潜能。结果：酶消化法分离培养的脐带MSCs 1 d后，细胞贴壁呈成纤维形，2 d后呈漩涡状生长且增殖明显，3 d后达80%融合即可传代；应用密度梯度离心法分离骨髓MSCs，体外培养4 d后，细胞贴壁呈圆形、梭形和多角形生长，5 d后呈克隆样生长且增殖明显，7 d后达80%融合即可传代。原代培养的脐带MSCs生长曲线近似“S”形，骨髓MSCs 生长曲线较平缓；MTT法显示脐带MSCs在3～5 d增殖较明显，骨髓MSCs 7 d后细胞增殖较明显。2种P3细胞传代成活率均为96%以上，G0/G1期细胞均为85%以上，无明显差异（P>0.05）；2种P3细胞CD44、CD90和CD105阳性率均为(60.7±2.3)%以上高表达，CD45、CD19、CD14和CD79a均为(25.6±4.8)%低表达，两者无明显差异（P>0.05）；2种MSCs在体外均具有向成骨细胞和成脂细胞分化的潜能，脐带MSCs向成骨及成脂细胞分化率均为90%以上，与骨髓MSCs的分化潜能比较有显著差异（P<0.05）。结论：脐带MSCs较骨髓MSCs具有较强的增殖能力及分化潜能。绿色荧光蛋白转基因小鼠的脐带MSCs可作为较好干细胞示踪的细胞源。

Biological characteristics of mesenchymal stem cells from different resources in green fluorescent protein transgenic mice

AIM：To compare the biological characteristics, surface markers and multi-differentiation potential of the mesenchymal stem cells (MSCs) derived from the umbilical cord and bone marrow in the green fluorescent protein (GFP) transgenic mice. METHODS：Umbilical cord MSCs (UCMSCs) were isolated by collagen type II enzymatic digestion and bone marrow MSCs (BMSCs) were isolated by density gradient centrifugation. The growth of the 2 types of MSCs was observed under inverted microscope. The cell proliferation was detected by determining the growth curve and MTT assay. The Trypan blue method was performed to analyze the cell viability rate. The cell cycle and cell surface markers were measured by flow cytometry. The differentiation potentials of the 2 types of MSCs were tested by the differentiation kits toward adipocytes and osteoblasts. RESULTS：The UCMSCs attached to the culture surface 1 d after the isolation, and the cells showed spiral shape with notable growth and proliferation after 2 d of culture. After 3 d, the cell arrived sub-confluent and was ready for passage. BMSCs still showed circular shape and started to attach to the surface 4 d after culture. They formed the small colony shape only after 5 d with obvious proliferative potential. The cells became confluent 7 d after the culture. The original generation of cultivating UCMSCs growth curve was shown typically an “S” shape. But the BMSCs growth was slower than the UCMSCs. The cell proliferation was obvious for UC-MSCs in 3~5 d. BMSCs proliferated significantly only after 7 d. The viability rate arrived more than 96% for both types of MSCs. The cell cycle of both MSCs did not show significant difference (G0/G1 phases were above 85%, P>0.05). Both MSCs positively expressed CD44, CD90 and CD105 (60.7%±2.3%) but the expression of CD45, CD19, CD14 and CD79 was negative (less than 25.6%±4.8%, P>0.05). More than 90% of the MSCs from the umbilical cord and bone marrow differentiated towards the adipocytes and osteoblasts without significant difference (P<0.05). CONCLUSION：UCMSCs have stronger ability of proliferation and multi-directional differentiation potentials. UCMSCs in GFP transgenic mice as a high-quality tracer can serve for tracking the stem cells in vivo.