不同基因转染对骨髓基质干细胞成骨活性的影响

为了优化骨组织工程种子细胞，探讨不同基因对骨髓基质干细胞（MSCs）成骨活性的影响，我们首先利用RT—PCR方法获得了全长BMP-2．VEGF 165及bFGF基因，克隆入真核表达载体peDNA3．0，鉴定正确后，经脂质体介导转入分离培养的大鼠骨髓基质干细胞，G418筛选出稳定表达株。并利用RT—PCR、免疫组织化学方法证明目的基因能够在骨髓基质干细胞中得到稳定表达。MTT实验结果显示转基因后的MSCs增殖能力有不同程度的提高。细胞内碱性磷酸酶活性明显上调，BMP-2、bFGF转染组骨钙索水平升高，成骨活性增强。提示：BMP-2、bFGF基因修饰的骨髓基质干细胞作为种子细胞能够更为有效地在骨组织工程中发挥作用。     

透明质酸钠可作为成骨诱导后骨髓间充质干细胞的载体

目的:研究透明质酸钠作为组织工程骨支架的可行性.方法:体外培养兔骨髓间充质干细胞(MSCs),在成骨诱导剂地塞米松等的诱导下,向成骨细胞转化,并使之与透明质酸钠凝胶复合,通过倒置相差显微镜和扫描电子显微镜观察细胞贴附情况.结果:地塞米松等诱导组细胞形态向类成骨细胞转化,碱性磷酸酶表达明显增高,并表达Ⅰ型胶原.体外复合培养10 h,成骨细胞即开始于透明质酸钠凝胶中伸展生长,复合培养7 d,成骨细胞在凝胶中分化增殖,分泌细胞外基质.结论:适当浓度成骨诱导剂可成功地将兔MSCs向成骨细胞诱导,透明质酸钠是骨组织工程的良好载体.     

骨髓间充质干细胞在骨组织工程中的研究进展

近20年来，组织工程取得了迅猛发展，为骨缺损修复提供了新的思路和治疗途径，要构建理想的的组织工程化骨其前提就是要有生物学特性良好的种子细胞和适合的支架材料，随着干细胞研究的不断深入，给组织工程种子细胞的选择带来了新的希望。目前，可应用于骨组织工程的种子细胞中，骨髓间充质干细胞（bone marrow mesenchymal stem cells，MSCs），因其可通过体外贴壁培养分离，扩增迅速，是一类具有分化潜能的细胞，在特定条件下可以分化为多种组织细胞，如成骨细胞、软骨细胞、肌腱、脂肪细胞、成纤维细胞以及神经星状细胞等，且具有极强的自我复制能力，是一种重要组织工程种子细胞。本文就骨髓间充质干细胞作为骨组织工程的种子细胞的国内外研究进展简要做一综述。     

成骨诱导:兔骨髓间充质干细胞的形态和功能特征

目的 探讨体外成骨诱导的兔骨髓间充质干细胞(MSCs)的形态和功能特征，为骨组织工程中种子细胞的研究提供依据。方法 选用生长状态良好的传l代的兔MSCs，在体外进行成骨活性诱导，并进行形态学观察和碱性磷酸酶、骨钙紊等功能性指标的检测。结果 体外成骨诱导的兔骨髓间充质干细胞从诱导的第2周即开始表达成骨细胞的活性，到第4周趋于成熟，此过程中性态和功能均具有一定的阶段性。结论 经过体外成骨诱导的兔MSCs表现出典型的成骨细胞阶段性形态特征和功能特征，可以作为骨组织工程的种子细胞。     

兔骨髓基质细胞诱导成骨细胞复合同种异体生物衍生骨实验研究

目的探讨体外培养的骨髓基质细胞与自体来源的生物衍生骨复合后的生长特性，为进一步研究骨髓基质细胞作为种子细胞，以及探索一种良好的支架材料提供实验依据。方法分离纯化兔骨髓基质细胞并诱导成成骨细胞后与同种异体来源的生物衍生骨复合后体外培养，并在相差显微镜和扫描电镜下观察其生长情况。结果骨髓基质细胞在生物衍生骨上贴附生长、增殖良好。结论骨髓基质细胞可作为骨组织工程的理想种子细胞，与生物衍生骨复合后可作为骨组织工程的载体。     

生物支架材料促进骨髓间充质干细胞成骨分化的研究热点北大核心

背景:目前单一生物支架材料难以满足骨组织工程的成骨需要,骨髓间充质干细胞具有优良的成骨特点,复合支架材料及复合生长因子的支架具有更优良的成骨能力,是目前研究的热点。目的:对不同生物支架材料及其改型后促进骨髓间充质干细胞成骨分化进行综述。方法:由第一作者通过检索中国知网、万方、维普、PubMed、Embase数据库2014年1月至2020年7月发表的相关文献,检索词为"骨髓间充质干细胞,支架,成骨分化,羟基磷灰石,胶原,壳聚糖;Bone marrow mesenchymal stem cells,scaffold,osteogenic,hydroxyapatite,collagen,chitosan",最终选取符合标准的文献69篇。结果与结论:骨组织工程的飞速发展可有效解决骨缺损修复的难题,种子细胞和生物支架材料是骨组织工程的核心内容。骨髓间充质干细胞具有优良的成骨分化能力,被广泛应用于骨组织工程。将不同的支架材料复合,利用先进的制备工艺或者进行支架的表面修饰、添加生长因子等可充分结合各种生物支架材料的优点,诱导骨髓间充质干细胞的成骨分化和支架血管的形成,达到修复骨缺损的目的,是骨组织工程的研究热点。     

骨髓间充质干细胞复合去抗原松质骨修复骨缺损的实验研究

目的 探讨骨髓间充质干细胞离体培养并与去抗原牛松质骨复合修复节段性骨缺损的效果。方法 Wistar大鼠骨髓间充质干细胞(MSCs)与去抗原牛松质骨(BCB)制成MSCs／BCB复合物；采用同种异体大鼠桡骨干5mm节段性骨缺损动物模型，通过X线放射学、组织学、生物力学检测对比研究骨缺损修复情况。结果 术后2、4、8、14、18周实验组与实验对照组经放射学检查评价新骨生成有显著性差异。术后组织学检查新骨生成速度、生成量均有显著性差异。18周经生物力学实验检测，实验组与实验对照组新骨生成有显著性差异，实验组标本与正常基本一致。空白对照组各时间点均无新骨形成，最后缺损由纤维组织充填。结论 大鼠骨髓间充质干细胞(MSCs)是骨组织工程中适宜的种子细胞。去抗原牛松质骨是可以选择的细胞载体。MSCs／BCB复合物植入修复骨缺损效果明显优于单纯BCB植入。     

骨髓间充质干细胞与纳米羟基磷灰石复合骨修复材料的研究进展

随着骨组织工程的发展,纳米羟基磷灰石（nHA）作为一种新型的骨组织支架材料应运而生,而骨髓间充质干细胞（BMSCs）是骨组织工程中一种理想的种子细胞。目前,BMSCs 与 nHA 复合后的骨修复材料用于临床的技术和条件还不完善。本研究通过对骨髓间充质干细胞和纳米羟基磷灰石的复合以及复合后BMSCs 增殖、分化、坏死、凋亡、矿化以及 nHA 支架材料体内降解的检测技术和指标进行概述,同时对二者复合的影响因素进行综述,为骨髓间充质干细胞与纳米羟基磷灰石复合骨修复材料应用于临床提供依据。     

骨髓间充质干细胞复合去抗原松质骨修复骨缺损的实验研究

目的探讨骨髓间充质干细胞离体培养并与去抗原牛松质骨复合修复节段性骨缺损的效果.方法 Wistar大鼠骨髓间充质干细胞(MSCs)与去抗原牛松质骨(BCB)制成MSCs/ BCB复合物;采用同种异体大鼠桡骨干5mm节段性骨缺损动物模型,通过X线放射学、组织学、生物力学检测对比研究骨缺损修复情况.结果术后2、4、8、14、18周实验组与实验对照组经放射学检查评价新骨生成有显著性差异.术后组织学检查新骨生成速度、生成量均有显著性差异.18周经生物力学实验检测,实验组与实验对照组新骨生成有显著性差异, 实验组标本与正常基本一致.空白对照组各时间点均无新骨形成,最后缺损由纤维组织充填.结论大鼠骨髓间充质干细胞(MSCs)是骨组织工程中适宜的种子细胞.去抗原牛松质骨是可以选择的细胞载体.MSCs/BCB复合物植入修复骨缺损效果明显优于单纯BCB植入.     

流体剪切力作用下间充质干细胞在三维支架上生长率理论模型的优化

骨组织工程是目前治疗大段骨缺损措施中最有发展前景的途径之一,体外构建骨组织工程移植体时常采用生物反应器对细胞—支架复合体进行灌流培养,以获得具有良好修复效果的骨组织工程移植体。但目前对这一过程中种子细胞(特别是干细胞)生长率的理论建模还不完善,尤其是忽略了干细胞与终末细胞的差异。在本实验室前期研究基础上,本文利用实验室自制的灌流装置对细胞支架复合体施加不同模式和大小的流体剪切力刺激,考察流体剪切力对间充质干细胞(MSCs)增殖和成骨分化的影响,建立了流体剪切力作用对MSCs单个细胞生长率影响的回归分析模型。结果表明,0.022 5 Pa振荡剪切力更能促进MSCs增殖和成骨分化,同时修正了流体剪切力作用下MSCs单个细胞生长率的理论模型。基于以上结果,希望本文研究可为骨组织工程移植体体外灌流培养条件的优化提供理论指导。     

Development of custom-built bone scaffolds using mesenchymal stem cells and apatite-wollastonite glass-ceramics

There is a clinical need for new bone replacement materials that combine long implant life with complete integration and appropriate mechanical properties. We have used human mesenchymal stem cells (MSCs) to populate porous apatite-wollastonite (A-W) glass-ceramic scaffolds produced by the layer manufacturing technique, selective laser sintering, to create custom-built bone replacements. Confocal and scanning electron microscopy were used to determine optimal seeding densities and to demonstrate that MSCs adhered and retained viability on the surface of A-W scaffolds over a culture period of 21 days. We found a significant increase in the number of MSCs growing on the scaffolds over 7 days. Using bromodeoxyuridine incorporation we demonstrated that MSCs proliferated on the scaffolds. Using real-time PCR we analyzed the expression of the osteogenic markers alkaline phosphatase, collagen type-I, Cbfa-1, osteocalcin, osteonectin, and osteopontin by MSCs cultured in the absence of osteogenic supplements. The expression of the osteogenic markers by MSCs was equivalent to or significantly greater on A-W scaffolds than on tissue culture plastic. We also identified significantly higher alkaline phosphatase activity on A-W compared to a commercial calcium phosphate scaffold. These results indicate for the first time the biocompatibility and osteo-supportive capacity of A-W scaffolds and their potential as patient-specific bone replacement materials.     

间充质干细胞在组织工程气管中的研究进展

组织工程学通过细胞或组织重建,修复缺损组织并保留其生物功能,成为气管替代治疗的新途径.种子细胞、生长因子及气管支架材料是组织工程气管的三大要素,学者们一直在寻求理想的种子细胞.间充质干细胞(MSCs)是一种具有高度自我更新能力和多向分化潜能的干细胞,广泛分布于骨髓、脐带、脂肪组织、心肌组织、大脑、肌肉和皮肤等,可向骨、软骨、脂肪、神经等多种细胞定向分化.MSCs具有增殖能力强、分化范围广、免疫调节等功能特点,能够修复损伤的组织,有望成为应用于组织工程气管的理想种子细胞.旨在对MSCs在组织工程气管中的应用作一综述.     

The bone formation in vitro and mandibular defect repair using PLGA porous scaffolds

Highly porous scaffolds of poly(lactide-co-glycolide) (PLGA) were prepared by solution-casting/salt-leaching method. The in vitro degradation behavior of PLGA scaffold was investigated by measuring the change of normalized weight, water absorption, pH, and molecular weight during degradation period. Mesenchymal stem cells (MSCs) were seeded and cultured in three-dimensional PLGA scaffolds to fabricate in vitro tissue engineering bone, which was investigated by cell morphology, cell number and deposition of mineralized matrix. The proliferation of seeded MSCs and their differentiated function were demonstrated by experimental results. To compare the reconstructive functions of different groups, mandibular defect repair of rabbit was made with PLGA/MSCs tissue engineering bone, control PLGA scaffold, and blank group without scaffold. Histopathologic methods were used to estimate the reconstructive functions. The result suggests that it is feasible to regenerate bone tissue in vitro using PLGA foams with pore size ranging from 100-250 microm as scaffolding for the transplantation of MSCs, and the PLGA/MSCs tissue engineering bone can greatly promote cell growth and have better healing functions for mandibular defect repair. The defect can be completely recuperated after 3 months with PLGA/MSCs tissue engineering bone, and the contrastive experiments show that the defects could not be repaired with blank PLGA scaffold. PLGA/MSCs tissue engineering bone has great potential as appropriate replacement for successful repair of bone defect.     

In vitro cultivation of canine multipotent mesenchymal stromal cells on collagen membranes treated with hyaluronic acid for cell therapy and tissue regeneration

Support structures for dermal regeneration are composed of biodegradable and bioresorbable polymers, animal skin or tendons, or are bacteria products. The use of such materials is controversial due to their low efficiency. An important area within tissue engineering is the application of multipotent mesenchymal stromal cells (MSCs) to reparative surgery. The combined use of biodegradable membranes with stem cell therapy may lead to promising results for patients undergoing unsuccessful conventional treatments. Thus, the aim of this study was to test the efficacy of using membranes composed of anionic collagen with or without the addition of hyaluronic acid (HA) as a substrate for adhesion and in vitro differentiation of bone marrow-derived canine MSCs. The benefit of basic fibroblast growth factor (bFGF) on the differentiation of cells in culture was also tested. MSCs were collected from dog bone marrow, isolated and grown on collagen scaffolds with or without HA. Cell viability, proliferation rate, and cellular toxicity were analyzed after 7 days. The cultured cells showed uniform growth and morphological characteristics of undifferentiated MSCs, which demonstrated that MSCs successfully adapted to the culture conditions established by collagen scaffolds with or without HA. This demonstrates that such scaffolds are promising for applications to tissue regeneration. bFGF significantly increased the proliferative rate of MSCs by 63% when compared to groups without the addition of the growth factor. However, the addition of bFGF becomes limiting, since it has an inhibitory effect at high concentrations in culture medium.     

Collagen microgel-assisted dexamethasone release from PLLA-collagen hybrid scaffolds of controlled pore structure for osteogenic differentiation of mesenchymal stem cells

Directed stem cell differentiation over three-dimensional porous scaffolds capable of releasing bioactive instructive cues is an important tool in tissue engineering. In this research, we have prepared dexamethasone (Dex)-releasing collagen microbead-functionalized poly(L-Lactide)-collagen hybrid scaffolds as an osteoinductive platform for human bone marrow-derived mesenchymal stem cells (MSCs). The scaffolds were prepared by a combined method of emulsion freeze-drying and porogen-leaching using pre-prepared ice collagen particulates as a porogen material. Dex release from the hybrid scaffolds was studied at 37?°C under shaking condition and the impact of released Dex towards osteogenic lineage differentiation was investigated by 3?week in vitro culture of MSCs. The results showed that hybrid scaffolds had controlled pore structure and interconnected pores deposited with collagen fibers. The hybrid scaffold facilitated cell seeding and the spatial localization of Dex/collagen microbeads facilitated a microgel-assisted spatio-temporal control of Dex release. The released Dex was useful for osteogenic differentiation of MSCs, which was confirmed from the elevated expression of osteogenic-specific gene-encoded proteins. The hybrid scaffolds should be useful for regeneration of a functional bone tissue.     

Biocompatibility and osteogenesis of biomimetic nano-hydroxyapatite/polyamide composite scaffolds for bone tissue engineering

In this study, we prepared nano-hydroxyapatite/polyamide (n-HA/PA) composite scaffolds utilizing thermally induced phase inversion processing technique. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized. Mesenchymal stem cells (MSCs) derived from bone marrow of neonatal rabbits were cultured, expanded and seeded on n-HA/PA scaffolds. The MSC/scaffold constructs were cultured for up to 7 days and the adhesion, proliferation and differentiation of MSCs into osteoblastic phenotype were determined using MTT assay, alkaline phosphatase (ALP) activity and collagen type I (COL I) immunohistochemical staining and scanning electronic microscopy (SEM). The results confirm that n-HA/PA scaffolds are biocompatible and have no negative effects on the MSCs in vitro. To investigate the in vivo biocompatibility and osteogenesis of the composite scaffolds, both pure n-HA/PA scaffolds and MSC/scaffold constructs were implanted in rabbit mandibles and studied histologically and microradiographically. The results show that n-HA/PA composite scaffolds exhibit good biocompatibility and extensive osteoconductivity with host bone. Moreover, the introduction of MSCs to the scaffolds dramatically enhanced the efficiency of new bone formation, especially at the initial stage after implantation. In long term (more than 12 weeks implantation), however, the pure scaffolds show as good biocompatibility and osteogenesis as the hybrid ones. All these results indicate that the scaffolds fulfill the basic requirements of bone tissue engineering scaffold, and have the potential to be applied in orthopedic, reconstructive and maxillofacial surgery.     

In vitro cartilage tissue engineering with 3D porous aqueous-derived silk scaffolds and mesenchymal stem cells

Adult cartilage tissue has limited self-repair capacity, especially in the case of severe damages caused by developmental abnormalities, trauma, or aging-related degeneration like osteoarthritis. Adult mesenchymal stem cells (MSCs) have the potential to differentiate into cells of different lineages including bone, cartilage, and fat. In vitro cartilage tissue engineering using autologous MSCs and three-dimensional (3-D) porous scaffolds has the potential for the successful repair of severe cartilage damage. Ideally, scaffolds designed for cartilage tissue engineering should have optimal structural and mechanical properties, excellent biocompatibility, controlled degradation rate, and good handling characteristics. In the present work, a novel, highly porous silk scaffold was developed by an aqueous process according to these criteria and subsequently combined with MSCs for in vitro cartilage tissue engineering. Chondrogenesis of MSCs in the silk scaffold was evident by real-time RT-PCR analysis for cartilage-specific ECM gene markers, histological and immunohistochemical evaluations of cartilage-specific ECM components. Dexamethasone and TGF-beta3 were essential for the survival, proliferation and chondrogenesis of MSCs in the silk scaffolds. The attachment, proliferation, and differentiation of MSCs in the silk scaffold showed unique characteristics. After 3 weeks of cultivation, the spatial cell arrangement and the collagen type-II distribution in the MSCs-silk scaffold constructs resembles those in native articular cartilage tissue, suggesting promise for these novel 3-D degradable silk-based scaffolds in MSC-based cartilage repair. Further in vivo evaluation is necessary to fully recognize the clinical relevance of these observations.     

Scaffold porosity and oxygenation of printed hydrogel constructs affect functionality of embedded osteogenic progenitors

Insufficient supply of oxygen and nutrients throughout the graft is considered one of the principal limitations in development of large, tissue-engineered bone grafts. Organ or tissue printing by means of three-dimensional (3D) fiber deposition is a novel modality in regenerative medicine that combines pore formation and defined cell placement, and is used here for development of cell-laden hydrogel structures with reproducible internal architecture to sustain oxygen supply and to support adequate tissue development. In this study we tested the effect of porosity on multipotent stromal cells (MSCs) embedded in hydrogel constructs printed with a 3D fiber deposition (3DF) machine. For this, porous and solid alginate hydrogel scaffolds, with MSCs homogeneously dispersed throughout the construct, were printed and analyzed in vitro for the presence of hypoxia markers, metabolism, survival, and osteogenic differentiation. We demonstrated that porosity promotes oxygenation of MSCs in printed hydrogel scaffolds and supported the viability and osteogenic differentiation of embedded cells. Porous and solid printed constructs were subsequently implanted subcutaneously in immunodeficient mice to analyze tissue formation in relation to hypoxia responses of embedded cells. Implantation of printed grafts resulted in ingrowth of vascularized tissue and significantly enhanced oxygenation of embedded MSCs. In conclusion, the introduction of pores significantly enhances the conductive properties of printed hydrogel constructs and contributes to the functionality of embedded osteogenic progenitors.     

The addition of biphasic calcium phosphate to porous chitosan scaffolds enhances bone tissue development in vitro

Uniform distribution of cells and their extracellular matrix is essential for the in vivo success of bone tissue engineering constructs produced in vitro. In this study, the effects of biphasic calcium phosphate (BCP) granules embedded into chitosan scaffolds on the distribution, morphology, and phenotypic expression of osteoblastic cells were investigated. Mesenchymal stem cells (MSCs) and preosteoblasts were cultured on chitosan scaffolds with and without BCP under osteoblastic differentiation/maturation conditions for periods up to 4 weeks. The addition of 25 wt % BCP to chitosan created a uniform layer of calcium phosphate (CaP) precipitation similar to bone mineral on the scaffold surfaces as determined by scanning electron microscopy and X-ray spectroscopy. Scaffolds with this CaP layer yielded more uniform and complete cell and ECM distribution than chitosan scaffolds without BCP. The suggestion of chemotaxis in the appearance of this response was confirmed by successive experiments in a Boyden chamber. The CaP layer also altered morphology of cells initially attached to the scaffold surfaces, leading to higher expression of marker proteins of osteoblastic phenotype including alkaline phosphatase and osteocalcin. The use of chitosan/BCP scaffolds for culture of MSCs and preosteoblasts enhances bone tissue development in vitro.     

骨髓间充质干细胞与不同基质修饰的纳米晶胶原基骨体外生物相容性研究

研究大鼠骨髓间充质干细胞(MSCs)诱导培养后与不同基质修饰的纳米晶胶原基骨(nanoHydroxyapatite/collagen,nHAC)的生物相容性,为骨组织工程提供一种新型复合支架材料。SD大鼠MSCs经成骨诱导培养、扩增,进行成骨细胞表征后,种植与支架材料体外复合培养。实验分为4组:实验组A,纤维蛋白(FB)和纤维连接蛋白(FN)修饰的纳米晶胶原基骨((FB FN)-nHAC);实验组B,纤维蛋白修饰的纳米晶胶原基骨(FB-nHAC);实验组C,纤维连接蛋白修饰的纳米晶胶原基骨(FN-nHAC);对照组D,单纯的纳米晶胶原基骨(nHAC)。通过检测支架材料的细胞黏附率、不同时间点(3、7、10、14d)支架材料中细胞数、碱性磷酸酶活性以及扫描电镜观察细胞在材料上的生长状况,比较分析不同支架材料与细胞生物相容性差异。大鼠MSCs经诱导培养14d后,碱性磷酸酶细胞化学染色、I型胶原免疫荧光染色及矿化沉积茜素红染色均为阳性;细胞与支架材料黏附率A组最高为74.4%;支架材料中细胞数量均随培养时间延长而增长,且A组细胞数增加较快,与相同时相点其他各组材料中细胞数差异有显著性(P<0.05);各时相点细胞碱性磷酸酶活性表达A组最高,差异亦有显著性(P<0.05)。电镜观察发现4组材料上均有细胞生长,但A组的细胞生长状况明显好于其他组。大鼠MSCs经成骨诱导培养,可表达成骨细胞表型,(FB FN)-nHAC在体外实验中表现出与细胞优良的生物相容性,可作为较理想的新型复合支架应用于骨组织工程。