Calcium deposition in photocrosslinked poly(Pro‐Hyp‐Gly) hydrogels encapsulated rat bone marrow stromal cells

Reproducing the features of the extracellular matrix is important for fabricating three‐dimensional (3D) scaffolds for tissue regeneration. A collagen‐like polypeptide, poly(Pro‐Hyp‐Gly), is a promising material for 3D scaffolds because of its excellent physical properties, biocompatibility, and biodegradability. In this paper, we present a novel photocrosslinked poly(Pro‐Hyp‐Gly) hydrogel as a 3D scaffold for simultaneous rat bone marrow stromal cell (rBMSC) encapsulation. The hydrogels were fabricated using visible‐light photocrosslinking at various concentrations of methacrylated poly(Pro‐Hyp‐Gly) (20–50 mg/ml) and irradiation times (3 or 5 min). The results show that the rBMSCs encapsulated in the hydrogels survived 7 days of incubation. Calcium deposition on the encapsulated rBMSCs was assessed with scanning electron microscope observation, Alizarin Red S, and von Kossa staining. The most strongly stained area was observed in the hydrogel formed with 30 mg/ml of methacrylated poly(Pro‐Hyp‐Gly) with 5‐min irradiation. These findings demonstrate that poly(Pro‐Hyp‐Gly) hydrogels support rBMSC viability and differentiation, as well as demonstrating the feasibility of using poly(Pro‐Hyp‐Gly) hydrogels as a cytocompatible, biodegradable 3D scaffold for tissue regeneration.     

低频脉冲电磁场诱导大鼠骨髓间充质干细胞软骨样细胞分化

骨髓间充质干细胞(BMSCs)是一类具有多向分化潜能的细胞。低频脉冲电磁场(LEPEMFs)治疗可导致哺乳动物细胞水平的生物化学变化,加速组织修复。因此,我们假设LFPEMFs可以促进体外大鼠骨髓间充质干细胞(rBMSCs)向软骨样细胞分化。实验分为3组:1)LFPEMFs组,rBMSCs暴露于50Hz、1mT低频脉冲电磁场,30min/d;2)成软骨诱导组,采用软骨诱导介质培养rBMSCs;3)对照组,采用完全培养介质培养rBMSCs。通过倒置相差显微镜逐日连续观察rBMSCs的生长状况和形态特征。分别于实验第10、15和20d收集各组rBMSCs标本,采用实时荧光定量PCR方法检测Ⅱ型胶原(ColⅡ)和聚集蛋白聚糖(aggrecan)mRNA表达,采用组织化学与免疫组化方法检测aggrecan和ColⅡ的蛋白表达。结果表明:在各时间点,LFPEMFs组与成软骨诱导组的ColⅡ、ag-grecan mRNA表达和蛋白表达明显高于对照组(P<0.05)。本实验提示,LFPEMFs可以促进rBMSCs向软骨样细胞分化。     

槲皮苷对大鼠骨髓间充质干细胞（rBMSCs）成骨分化和成脂分化的分子调控机制研究

Objective:The study was designed to investigate the molecular mechanism of quercitrin on osteogenic differentiation and adipogenic differentiation of r BMSCs.Methods:r BMSCs were harvested from SD rats,and determination of alkaline phosphatase(ALP)activity,quantification of mineralization by Alizarin Red S staining,and the m RNA expression of osteogenic differentiation markers(Runx2,BMP-2,and OSX)by RT-PCR after r BMSCs stimulated by osteogenic induction with(0.1–10)μg/m L of quercitrin,quantification of Lipid droplet by Oil Red O staining and the m RNA expression of adipogenic differentiation marker(,and a P2)by RT-PCR after r BMSCs stimulated by adipogenic induction with(0.1-10)μg/m L of quercitrin.Results:Quercitrin can up-regulate the m RNA expression of osteogenic differentiation markers(Runx2,BMP-2,and OSX)and increase ALP activity and mineralization after osteogenic induction,on the other hand quercitrin can suppress the m RNA expression of adipogenic differentiation markers(,and a P2)and decrease lipid droplet after adipogenic induction.Conclusion:This study suggested that quercitrin not only stimulated osteogenic differentiation but also inhibited adipogenic differentiation of r BMSCs,which was associated with the up-regulation of Runx2,BMP-2,and OSX m RNA expression and the down-regulation of,and a P2 m RNA expression.     

力学刺激和成骨化学诱导剂对大鼠骨髓间充质干细胞成骨分化能力的影响

目的 探讨力学刺激与成骨化学诱导剂对大鼠骨髓间充质干细胞（rat bone mesenchymal stem cells,rBMSCs）碱性磷酸酶（alkaline phosphatase, ALP）、I 型胶原(collagen type I, COL I）和骨钙素 (osteocalcin, OCN) 基因表达与钙化结节形成的影响。方法 体外分离培养rBMSCs,分别在成骨诱导和非成骨诱导条件下应用双轴力学应变加载系统对rBMSCs施加周期性的机械张应变（应变2%,频率1 Hz,每次2 h,间隔2 h,每天加载3 次）。力学刺激作用3 d和6 d,采用实时荧光定量RT-PCR检测ALP、COL I和OCN的mRNA表达,同时采用茜素红染色法观察钙化结节的形成情况。结果 力学刺激作用后,成骨诱导6 d组出现明显的钙化结节,其余各组均无明显钙化结节形成。与相应非诱导组比较,成骨诱导3 d组ALP、COL I和OCN的mRNA表达量分别增加0.6、3和11.8倍;成骨诱导6 d组ALP、COL I和OCN的mRNA表达量分别增加2.7、3.2和10倍。结论 成骨化学诱导剂和力学刺激均能促进rBMSCs的骨向分化,且二者之间具有协同作用。     

Influence of the intensity and loading time of direct current electric field on the directional migration of rat bone marrow mesenchymal stem cells

Exogenic electric fields can effectively accelerate bone healing and remodeling through the enhanced migration of bone marrow mesenchymal stem cells (BMSCs) toward the injured area. This study aimed to determine the following: (1) the direction of rat BMSC (rBMSC) migration upon exposure to a direct current electric field (DCEF), (2) the optimal DCEF intensity and duration, and (3) the possible regulatory role of SDF-1/CXCR4 axis in rBMSC migration as induced by DCEF. Results showed that rBMSCs migrated to the positive electrode of the DCEF, and that the DCEF of 200 mV/mm for 4 h was found to be optimal in enhancing rBMSC migration. This DCEF strength and duration also upregulated the expression of osteoblastic genes, including ALP and OCN, and upregulated the expression of ALP and Runx2 proteins. Moreover, when CXCR4 was inhibited, rBMSC migration due to DCEF was partially blocked. These findings indicated that DCEF can effectively induce rBMSC migration. A DCEF of 200 mV/mm for 4 h was recommended because of its ability to promote rBMSC migration, proliferation, and osteogenic differentiation. The SDF-1/CXCR4 signaling pathway may play an important role in regulating the DCEF-induced migration of rBMSCs.     

淫羊藿苷含药血清对体外培养骨髓间充质干细胞增殖及成骨性分化的影响

目的:研究淫羊藿苷含药血清(SI)对体外培养大鼠骨髓间充质干细胞(rBMSCs)增殖和成骨性分化的影响。方法:以每0.25g/kg质量淫羊藿苷的剂量灌服成年大鼠,制得淫羊藿苷含药血清,以灌服等体积生理盐水制得对照血清。分别以2.5%,5%和10%3种血清浓度干预rBMSCs,MTT法检测细胞增殖率,同时检测成骨性诱导培养9d后的碱性磷酸酶(ALP)活性,筛选出最佳血清浓度。以最佳血清浓度干预rBMSCs的成骨性分化,比较SI组和对照组之间的钙盐沉积量、骨钙素分泌量;提取Total RNA,RT-PCR检测IGF-1,Runx-2与Osterix mRNA的表达情况。结果:所有浓度的含药血清均能抑制rBMSCs的增殖,但可提高ALP活性。5%的SI浓度为最佳干预浓度,该浓度的含药血清可显著促进骨钙素的分泌和钙盐沉积,提高ALP活性,增强IGF-1,Runx-2与Osterix mRNA的表达。结论:淫羊藿苷经口服后的代谢产物抑制rBMSCs增殖,但可促进成骨性分化,提示淫羊藿苷可以通过口服途径给药,其代谢物是发挥抗骨质疏松活性的主要成分。     

麝香对颅骨骨缺损模型大鼠SDF-1表达的影响

目的 观察不同剂量麝香对颅骨骨缺损模型大鼠骨缺损处SDF-1表达的影响,探讨麝香促进外源性rBMSCs向骨缺损处迁移的机制.方法 采用贴壁筛选法培养rBMSCs,大鼠颅骨骨缺损模型的建立后回植rBMSCs,将模型组大鼠完全随机分为四组,高、中、低剂量组及空白对照组,并向高、中、低剂量组灌服麝香,空白对照组灌服生理盐水.14天后处死大鼠取出缺损部位的颅骨,并对其脱钙、制作切片.免疫组化染色,光学显微镜下观察,每个切片随机选取3个视野,进行统计学分析.结果 麝香能促进颅骨骨缺损模型大鼠骨缺损处SDF-1表达,给药各浓度组和空白组比较有显著统计学差异(P＜0.01),以低浓度效果最佳(P＜0.05).结论 麝香均促进外源性rBMSCs在大鼠体内向损伤部位迁移的机制与麝香促进颅骨骨缺损模型大鼠骨缺损处SDF-1表达有关.     

Rosmarinic acid protects on rat bone marrow mesenchymal stem cells from hydrogen peroxide-induced apoptosis

To investigate the anti-oxidant activities and mechanism of rosmarinic acid (RA) on rat bone marrow mesenchymal stem cells (rBMSCs) from ischemia-induced apoptosis in vitro, which was established using H₂O₂-damage and analyzed for cell viability, cell apoptosis, ROS, morphological changes, and levels of apoptosis proteins. Pretreatment with RA significantly suppressed the generation of ROS, protected the morphological changes of cells, decrease the ratio of cell apoptosis, down-regulated the level of caspase-3, caspase-9, Bax/Bcl-2, and up-regulated the level of p-PI3K. These findings suggest that RA may protect rBMSCs from H₂O₂-induced apoptosis by partly regulating PI3K/Akt signaling pathway and can be developed as a potential anti-apoptotic agent for therapy in cardiovascular diseases.     

苯妥英钠对大鼠骨髓间充质干细胞向血管内皮细胞分化的影响

目的：研究苯妥英钠（PHT）对大鼠骨髓间充质干细胞（rBMSCs）向血管内皮细胞（rVECs）分化的影响。方法：建立rBMSCs 与 rVECs 共培养组及 rBMSCs 单独培养组,各组分别添加不同浓度的 PHT（0、20、40μg／ml）,培养14 d 后 real-time PCR 检测各组细胞中 ICAM-1、VCAM-1、KDR 和 RUNX2基因的 mRNA 表达水平。结果：添加 PHT 后,各组细胞中 ICAM-1、KDR 和 RUNX2基因的 mRNA 表达均上调。添加相同浓度 PHT 时,共培养组较单独培养组中 rBMSCs 的 ICAM-1、KDR 和RUNX2基因的 mRNA 表达量增高,而 VCAM-1基因的 mRNA 表达量降低。结论：PHT 可能促进大鼠骨髓间充质干细胞向血管内皮细胞分化。     

骨髓间充质干细胞与纳米羟基磷灰石支架材料的体外相容性研究

目的　探讨兔骨髓间充质干细胞(rBMSCs)与纳米羟基磷灰石(nano-HA)支架材料的相容性,进一步验证nano-HA材料作为骨组织工程支架材料的可行性。 方法　将rBMSCs与nano-HA支架材料在体外复合培养,通过倒置显微镜、扫描电镜观察细胞与材料的复合情况,用MTT法、碱性磷酸酶活性检测法检测材料对细胞增殖、分化的影响。 结果　rBMSCs可以在nano-HA支架材料表面及孔隙中良好的黏附、迁移、增殖和分化,复合培养5 d后nano-HA支架材料对rBMSCs的增殖分化表现出一定的促进作用。 结论　rBMSCs与nano-HA支架材料具有良好的生物相容性, nano-HA支架材料可以作为rBMSCs良好的载体。