维甲酸和甲状腺激素在骨髓间充质干细胞软骨分化中的作用

目的 探讨甲状腺素(thyroxine, T3)和维甲酸(retinoic acid, RA)对骨髓间充质干细胞(bone marrow mesenchymal stem cells, BMSCs)软骨形成的影响。方法 在3种条件培养基中培养和诱导猪BMSCs成软骨分化：对照组使用软骨生成培养基(含10^-7 mol/L地塞米松和10 ng/mL转化生长因子β1),RA组采用软骨生成培养基加1μmol/L RA,T3组采用软骨生成培养基加100 nmol/L T3。采用MTT法单层检测BMSCs的增殖情况。收获第3代BMSCs,离心形成细胞颗粒，分为3组分别进行软骨细胞诱导。4周后采集3组的细胞颗粒，通过组织学染色和半定量基因表达分析进行软骨形成评估。结果 T3组BMSCs增殖高于对照组(P<0.05);RA组BMSCs增殖低于对照组(P<0.05);对照组BMSCs颗粒中观察到软骨特征的类腔隙结构和甲苯胺蓝阳性染色，RA组未见；RA组软骨发生标志基因ColⅡ、蛋白聚糖(aggrecan)和Sox9的表达与对照组相比显著降低，而肥大标志基因ColX的表达...

Role of retinoic acid and thyroid hormone in chondrogenic differentiation of bone marrow mesenchymal stem cells

Objective To investigate the effects of thyroxine (T3) and retinoic acid (RA) on chondrogenesis of bone marrow mesenchymal stem cells (BMSCs). Methods Porcine BMSCs were cultured and induced in three conditioned medium: control group was treated chondrogenic medium ［with 10^－7 mol/L dexamethasone and 10 ng/mL transforming growth factor-β1 (TGF-β1)］. RA group was treated chondrogenic medium plus 1 μmol/L RA. T3 group was treated chondrogenic medium plus 100 nmol/L T3. BMSCs proliferation was evaluated by MTT assay in a monolayer way. BMSCs pellets in the two groups were harvested after 4 weeks and were evaluated with histological staining and semi-quantitative gene expression analysis. Results BMSCs proliferation in T3 group was significantly higher than that of control group (P<0.05). BMSCs proliferation in RA group was significantly lower than that of control group (P<0.05). Lacuna-like structure and positive staining of toluidine blue were observed in BMSCs pellets of control group but not in RA group. Better lacuna like structure and positive staining of toluidine blue were observed in BMSCs pellets of T3 group. Expressions of marker genes of chondrogenesis, such as Col Ⅱ, aggrecan and Sox 9, were significantly decreased in RA group compared with control group at week 4, while expression of Col X, a marker gene of hypertrophy, was significantly increased in RA group. The expressions of osteogenesis-related genes Col Ⅰ and Runx 2 also decreased markedly (P<0.05). Expressions of Col Ⅱ, aggrecan and Sox9 were significantly increased in T3 group compared with control group at week 4, and expression of Col X was significantly increased in T3 group (P<0.05). There was no significant difference in the gene expressions of Col Ⅰ and Runx2 between the two groups (P>0.05). Conclusion RA inhibited proliferation and chondrogensis of BMSCs. T3 promoted the proliferation and chondrogenesis of BMSCs, but induced the hypertrophy of chondrocytes differentiated from BMSCs.