Bone formation using human adipose tissue-derived stromal cells and a biodegradable scaffold

Human adipose tissue, obtained by liposuction, was processed to obtain a fibroblast-like population of cells or adipose tissue-derived stromal cells (ATSCs). The ATSCs, as well as bone marrow-derived mesenchymal stem cells (BMSCs), have the capacity for renewal and the potential to differentiate into multiple lineages of mesenchymal tissues. These cells are capable of forming bone when implanted ectopically in an appropriate scaffold. The aim of this study was to evaluate a beta-tricalcium phosphate (beta-TCP) as a scaffold and to compare the potential of osteogenic differentiation of ATSCs with BMSCs. Both cell types were loaded into beta-TCP disk and cultured in an osteogenic induction medium. Optimal osteogenic differentiation in ATSCs in vitro, as determined by secretion of osteocalcin, scanning electron microscope, and histology, were obtained in the culturing with the beta-TCP disk. Furthermore, bone formation in vivo was examined by using the ATSC- or BMSC-loaded scaffolds in nude mice. The present results show that ATSCs have a similar ability to differentiate into osteoblasts and to synthesize bone in beta-TCP disk as have BMSCs.     

Hydrophilized 3D porous scaffold for effective plasmid DNA delivery

In this study, hydrophilic PLGA/Pluronic F127 scaffolds loaded with a pDNA/PEI-PEG complex were prepared to estimate their potential use as a polymeric matrix for pDNA delivery. The scaffold was fabricated by a novel precipitation/particulate leaching method. The prepared pDNA/PEI-PEG complex-loaded PLGA/Pluronic F127 scaffold exhibited a highly porous (porosity, 93-95%) and open pore structure, as well as hydrophilicity, which can provide the good environment for cell adhesion and growth. The pDNA/PEI-PEG complexes were efficiently loaded into the PLGA/Pluronic F127 scaffold and continuously released from the scaffolds up to ~90% of the initial loading amount over a period of 8 wk, which may lead to continuous gene transfection into human bone marrow mesenchymal stem cells (hBMMSCs). From the in vitro cell culture in the scaffolds for transfection, it was observed that the pDNA/PEI-PEG complex-loaded hydrophilic PLGA/Pluronic F127 scaffold has a higher transfection efficiency of the pDNA/PEI-PEG complexes into hBMMSCs than the hydrophobic PLGA ones. The cell viability associated with the pDNA/PEI-PEG complexes released from the PLGA/Pluronic F127 scaffold was not significantly different from that of the PLGA/Pluronic F127 scaffold without pDNA, indicating its low cytotoxicity, probably due to the sustained release of the pDNA/PEI-PEG complex from the scaffolds. From these results, we could suggest that the pDNA/PEI-PEG complex-loaded hydrophilic PLGA/Pluronic F127 scaffold can be an effective gene delivery system for 3D tissue formation.     

Adipose differentiation of bone marrow-derived mesenchymal stem cells using Pluronic F-127 hydrogel in vitro

Due to increasing clinical demand for adipose tissue, a suitable scaffold for engineering adipose tissue constructs is needed. In this study, we have developed a three-dimensional (3-D) culture system using bone marrow-derived mesenchymal stem cells (BM-MSC) and a Pluronic F-127 hydrogel scaffold as a step towards the in vitro tissue engineering of fat. BM-MSC were dispersed into a Pluronic F-127 hydrogel with or without type I collagen added. The adipogenic differentiation of the BM-MSC was assessed by cellular morphology and further confirmed by Oil Red O staining. The BM-MSC differentiated into adipocytes in Pluronic F-127 in the presence of adipogenic stimuli over a period of 2 weeks, with some differentiation present even in absence of such stimuli. The addition of type I collagen to the Pluronic F-127 caused the BM-MSC to aggregate into clumps, thereby generating an uneven adipogenic response, which was not desirable.     

Osteogenic potential of human adipose tissue-derived stromal cells as an alternative stem cell source

Adult bone marrow contains mesenchymal stem cells (bone marrow-derived mesenchymal stem cells; BMSCs) which contribute to the generation of mesenchymal tissue such as bone, cartilage, muscle and adipose. However, using bone marrow as a source of stem cells has the limitation of a low cell number. An alternate source of adult stem cells that could be obtained in large quantities, under local anesthesia, with minimal discomfort would be advantageous. Human adipose tissue obtained by liposuction was processed to obtain a fibroblast-like population of cells or adipose tissue-derived stromal cells (ATSCs). In this study, we compared the osteogenic differentiation of ATSCs with that of BMSCs. Both cell types were cultured in atelocollagen honeycomb-shaped scaffolds with a membrane seal (ACHMS scaffold) for three-dimensional culturing in a specific osteogenic induction medium. Optimal osteogenic differentiation in both cell types, as determined by alkaline phosphatase cytochemistry, secretion of osteocalcin, mineral (calcium phosphate) deposition and scanning electron microscopy, was obtained with the same three-dimensional culture. Furthermore, osteoblastic lining in vivo was examined using ATSC-seeded or BMSC-seeded scaffolds in nude mice. The present results show that ATSCs have a similar ability to differentiate into osteoblasts to that of BMSCs.     

Collagen I gel promotes homogenous osteogenic differentiation of adipose tissue-derived mesenchymal stem cells in serum-derived albumin scaffold

Repair of bone defects is a difficult clinical problem for reconstructive surgeons. Bone tissue engineering using an appropriate scaffold with cells is a new therapy for the repair of bone defects. The aim of this study was to evaluate the in vitro osteogenesis of canine adipose tissue-derived mesenchymal stem cells (Ad-MSCs) cultured in a combination of collagen I gel and a porous serum-derived albumin scaffold. A serum-derived albumin scaffold was prepared with canine serum by cross-linking and freeze-drying procedures. Ad-MSCs were seeded into serum-derived albumin scaffolds with or without collagen I gel, and were exposed to osteogenic differentiation conditions in vitro. After 28?days of in vitro culture, the distribution and osteogenic differentiation of Ad-MSCs cultured in the scaffold were evaluated by scanning electron microscopy, histology, immunohistochemistry, alkaline phosphatase (ALP) activity assay, and calcium colorimetric assay. Ad-MSCs showed more homogeneous distribution and osteogenic differentiation in the scaffold with collagen I gel than without collagen I gel. ALP activity and extracellular matrix mineralization in the construct with type I collagen were significantly higher than in the construct without type I collagen (p?<?0.05). In conclusion, the combination of collagen I gel and the serum-derived albumin scaffold enhanced osteogenic differentiation and homogenous distribution of Ad-MSCs.     

Temperature-induced cell detachment on immobilized pluronic surface

The Pluronic F68 and F127, a triblock copolymer of ethylene oxide and propylene oxide, was activated using carbonyldiimidazole (CDI), and CDI-activated Pluronic F68 and F127 was subsequently immobilized on the surface of a poly-L-lysine-coated polystyrene tissue culture flask. Cell culture was performed on the Pluronic-immobilized flask. The morphology of fibroblasts (L929 cells) on the Pluronic F127-immobilized flask was mainly spherical, and showed less spreading behavior than that on the Pluronic F68-immobilized flask and conventional tissue culture flask. This observation indicates that L929 cells on Pluronic F127-immobilized flasks were cultured in a bio-inert environment. L929 cells were successively detached from both Pluronic F127-immobilized flask and Pluronic F68-immobilized flask by cooling the flask to 4-15 degrees C. This detachment is due to the hydration and dehydration properties of Pluronic, depending on the temperature. Umbilical cord blood was cultured in the Pluronic F127-immobilized and conventional polystyrene tissue culture flasks at 37 degrees C. The expression ratio of surface markers on hematopoietic stem cells (CD34 and CD133) cultured in the Pluronic F127-immobilized flask was significantly higher than that of the cells in polystyrene tissue culture flask.     

Stem cells from adipose tissue allow challenging new concepts for regenerative medicine

The perspective of an innovative new concept integrating tissue-engineering techniques with an established surgical technique is described. The focus is primarily on a one-step surgical procedure using adipose tissue-derived mesenchymal stem cells, a calcium phosphate scaffold as a carrier, and a bioresorbable polymer cage to facilitate spinal interbody fusion. We address the harvesting and processing of clinically relevant quantities of adipose tissue-derived mesenchymal stem cells, triggering of these stem cells toward lineage-specific differentiation, seeding of the triggered stem cells on a bioresorbable scaffold, and implantation of the resulting tissue-engineered construct. The integrated steps can be accomplished within one surgical procedure in a surgical theater. Although the proposed concept has been developed for spinal fusion, potential application in other surgical disciplines is presumed realistic.     

Reconstruction of alveolar bone defects using bone morphogenetic protein 2 mediated rabbit dental pulp stem cells seeded on nano-hydroxyapatite/collagen/poly(L-lactide)

The objective of the present study was to evaluate the capacity of a tissue-engineered bone complex of recombinant human bone morphogenetic protein 2 (rhBMP-2)-mediated dental pulp stem cells (DPSCs) and nano-hydroxyapatite/collagen/poly(L-lactide) (nHAC/PLA) to reconstruct critical-size alveolar bone defects in New Zealand rabbit. Autologous DPSCs were isolated from rabbit dental pulp tissue and expanded ex vivo to enrich DPSCs numbers, and then their attachment and differentiation capability were evaluated when cultured on the culture plate or nHAC/PLA. The alveolar bone defects were treated with nHAC/PLA, nHAC/PLA+rhBMP-2, nHAC/PLA+DPSCs, nHAC/PLA+DPSCs+rhBMP-2, and autogenous bone (AB) obtained from iliac bone or were left untreated as a control. X-ray and a polychrome sequential fluorescent labeling were performed postoperatively and the animals were sacrificed 12 weeks after operation for histological observation and histomorphometric analysis. Our results showed that DPSCs expressed STRO-1 and vementin, and favored osteogenesis and adipogenesis in conditioned media. DPSCs attached and spread well, and retained their osteogenic phenotypes on nHAC/PLA. The rhBMP-2 could significantly increase protein content, alkaline phosphatase activity/protein, osteocalcin content, and mineral formation of DPSCs cultured on nHAC/PLA. The X-ray graph, the fluorescent, histological observation, and histomorphometric analysis showed that the nHAC/PLA+DPSCs+rhBMP-2 tissue-engineered bone complex had an earlier mineralization and more bone formation inside the scaffold than nHAC/PLA, nHAC/PLA+rhBMP-2, and nHAC/PLA+DPSCs, or even autologous bone. Implanted DPSCs' contribution to new bone was detected through transfected eGFP genes. Our findings indicated that stem cells existed in adult rabbit dental pulp tissue. The rhBMP-2 promoted osteogenic capability of DPSCs as a potential cell source for periodontal bone regeneration. The nHAC/PLA could serve as a good scaffold for autologous DPSC seeding, proliferation, and differentiation. The tissue-engineered bone complex with nHAC/PLA, rhBMP-2, and autologous DPSCs might be a better alternative to autologous bone for the clinical reconstruction of periodontal bone defects.     

Human umbilical cord mesenchymal stem cells: osteogenesis in vivo as seed cells for bone tissue engineering

Mesenchymal stem cells (MSCs) are ideal seed cells for bone tissue engineering. However, intrinsic deficiencies exist for the autologous transplantation strategy of constructing artificial bone with MSCs derived from bone marrow of patients. In this study, MSCs-like cells were isolated from human umbilical cords and were expanded in vitro. Flow cytometric analysis revealed that cells from the fourth passage were positive for CD29, CD44, CD71, CD73, CD90, and CD105 whereas they were negative for CD14, CD34, CD45, and CD117. Furthermore, these cells expressed HLA-A, B, C (MHC-I), but not HLA-DP, DQ, DR (MHC-II), or costimulatory molecules such as CD80 and CD86. Following incubation in specific inductive media for 3 weeks, cultured cells were shown to possess potential to differentiate into adipogenic, osteogenic or chondrogenic lineages in vitro. The umbilical cord-derived MSCs (UC-MSCs) were loaded with a biomimetic artificial bone scaffold material before being implanted subcutaneously in the back of Balb/c nude mice for four to twelve weeks. Our results revealed that UC-MSCs loaded with the scaffold displayed capacity of osteogenic differentiation leading to osteogenesis with human origin in vivo. As a readily available source of seed cells for bone tissue engineering, UC-MSCs should have broad application prospects.     

猪脂肪间充质干细胞分离、鉴定、诱导及联合扩张器重建乳房模型的研究

目的 通过从脂肪组织中提取脂肪间充质干细胞,并进行培养鉴定、定向诱导,再联合皮肤扩张器在小型猪腹部皮下塑造乳房重建模型,探讨脂肪间充质干细胞用于乳房重建的可能性.方法 取小型猪颈背部皮下脂肪组织,用胶原酶消化法获得脂肪间充质干细胞,结合免疫荧光法,将所培养细胞用流式细胞技术分析细胞表面抗原,体外诱导其向脂肪细胞、成骨细胞分化,油红O染色、茜素红染色等方法检测细胞诱导分化结果.筛选脂肪间充质干细胞,将脂肪间充质干细胞联合扩张器注射于小型猪乳房模型观察.结果 流式细胞技术检测CD34、CD45阴性表达,CD44、CD105阳性表达,油红O染色可见细胞内有脂滴形成,茜素红染色发现细胞出现钙结节.动物模型发现与对照组相比较,注入干细胞组局部细胞数目增多.结论 猪脂肪间充质干细胞可在体外培养,并可定向诱导成脂肪细胞、成骨细胞,在动物体内可向局部组织分化,引起局部细胞数目增多.     

Phenotypical and functional characterization of freshly isolated adipose tissue-derived stem cells

Adipose tissue contains a stromal vascular fraction (SVF) that is a rich source of adipose tissue-derived stem cells (ASCs). ASCs are multipotent and in vitro-expanded ASCs have the capacity to differentiate, into amongst others, adipocytes, chondrocytes, osteoblasts, and myocytes. For tissue engineering purposes, however, it would be advantageous to use the whole SVF, which can be transplanted without further in vitro selection or expansion steps. Because little is known about the freshly isolated ASCs in the SVF, we phenotypically characterized human freshly isolated ASCs, using flow cytometry. In addition, we investigated whether freshly isolated ASCs have functional properties comparable to cultured ASCs. For this, the differentiation potential of both freshly isolated ASCs and cultured ASCs into the osteogenic pathway was analyzed. Freshly isolated ASCs slightly differed in immunophenotype from cultured ASCs. Contrary to cultured ASCs, freshly isolated ASCs were shown to be highly positive for CD34, and positive for CD117 and HLA-DR. On the other hand, expression of CD105 and especially CD166 on the freshly isolated ASCs was relatively low. After osteogenic stimulation of freshly isolated ASCs, both Runx-2 and CollaI gene expression were significantly increased (p < 0.05). However, there was a difference in the kinetics of gene expression between freshly isolated and cultured ASCs and also between the different SVF isolates tested. There was no difference in alkaline phosphatase activity between freshly isolated ASCs and cultured ASCs. In addition, freshly isolated ASCs stained positive for osteonectin and showed matrix mineralization. We conclude that although there are minor differences in phenotype and kinetics of differentiation between freshly isolated ASCs and cultured ASCs, the use of freshly isolated ASCs for tissue engineering purposes involving bone repair is potentially applicable.     

Maxillary sinus floor elevation using a tissue-engineered bone with calcium-magnesium phosphate cement and bone marrow stromal cells in rabbits

The objective of this study was to assess the effects of maxillary sinus floor elevation with a tissue-engineered bone constructed with bone marrow stromal cells (bMSCs) and calcium-magnesium phosphate cement (CMPC) material. The calcium (Ca), magnesium (Mg), and phosphorus (P) ions released from calcium phosphate cement (CPC), magnesium phosphate cement (MPC), and CMPC were detected by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the proliferation and osteogenic differentiation of bMSCs seeded on CPC, MPC, and CMPC or cultured in CPC, MPC, and CMPC extracts were measured by MTT analysis, alkaline phosphatase (ALP) activity assay, alizarin red mineralization assay, and real-time PCR analysis of the osteogenic genes ALP and osteocalcin (OCN). Finally, bMSCs were combined with CPC, MPC, and CMPC and used for maxillary sinus floor elevation in rabbits, while CPC, MPC, or CMPC without cells served as control groups. The new bone formation in each group was detected by histological finding and fluorochrome labeling at weeks 2 and 8 after surgical operation. It was observed that the Ca ion concentrations of the CMPC and CPC scaffolds was significantly higher than that of the MPC scaffold, while the Mg ions concentration of CMPC and MPC was significantly higher than that of CPC. The bMSCs seeded on CMPC and MPC or cultured in their extracts proliferated more quickly than the cells seeded on CPC or cultured in its extract, respectively. The osteogenic differentiation of bMSCs seeded on CMPC and CPC or cultured in the corresponding extracts was significantly enhanced compared to that of bMSCs seeded on MPC or cultured in its extract; however, there was no significant difference between CMPC and CPC. As for maxillary sinus floor elevation in vivo, CMPC could promote more new bone formation and mineralization compared to CPC and MPC, while the addition of bMSCs could further enhance its new bone formation ability significantly. Our data suggest that CMPC possesses moderate biodegradability and excellent osteoconductivity, which may be attributed to its Ca and Mg ion composition, and the tissue-engineered bone constructed of CMPC and bMSCs might be a potential alterative graft for maxillofacial bone regeneration.     

大鼠骨髓间充质干细胞的体外成骨诱导*

背景：骨髓间充质干细胞作为良好的种子细胞,将其复合于生物支架治疗骨缺损取得了良好的进展,是当今研究的一大热点。 目的：观察大鼠骨髓间充质干细胞体外诱导向成骨样细胞分化的效果。 方法：采用贴壁筛选法分离培养SD大鼠骨髓间充质干细胞,取生长状态良好的第3代骨髓间充质干细胞,分为2组,对照组细胞仅用DMEM/F12培养基培养;实验组以含成骨诱导剂的DMEM/F12培养基培养。 结果与结论：全骨髓贴壁法培养的原代骨髓间充质干细胞呈梭形或多角形贴壁生长;经成骨诱导剂诱导后骨髓间充质干细胞呈圆形或卵圆形贴壁生长,碱性磷酸酶活性明显强于对照组(P < 0.01);茜素红染色出现阳性的钙化结节;Western blotting检测Ⅰ型胶原蛋白表达较对照组有明显增加(P < 0.01);骨钙素ELISA定量分析较对照组明显升高(P < 0.01)。提示全骨髓贴壁法培养骨髓间充质干细胞方法简单、实用,所培养的骨髓间充质干细胞在成骨诱导后表现了成骨细胞的形态学和生物学特性。     

预分化脂肪干细胞与纤维蛋白胶和磷酸钙骨水泥自体异位构建血管化移植物

背景：预构骨皮瓣研究启发人们构建预构血管化骨进行游离移植来替代带血管蒂游离自体骨移植修复大段骨缺损的想法。 目的：设计一种基于预分化脂肪干细胞、纤维蛋白胶和多孔磷酸钙骨水泥支架复合体的血管化移植物。 方法：将体外分离培养的大鼠脂肪干细胞在条件培养基中进行血管内皮细胞定向分化,经鉴定活性后,复合至纤维蛋白胶和多孔磷酸钙骨水泥构建血管化组织工程支架。将血管化组织工程支架、纤维蛋白胶/多孔磷酸钙骨水泥支架及多孔磷酸钙骨水泥支架分别植入SD大鼠股四头肌肌袋内,植入后2,4周进行组织学检测、血管定量分析和Western blot检测。 结果与结论：向血管内皮细胞分化的脂肪干细胞与纤维蛋白胶和多孔磷酸钙骨水泥共培养7 d,可见细胞密度适中,与支架组织结合较好。植入实验中,各组支架孔隙中充填有纤维血管组织和脂肪组织,血管化组织工程组支架孔隙中均长入大量血管,并有小动脉长入,不同时间点的血管直径和数量及血管内皮生长因子C的表达量均优于纤维蛋白胶/多孔磷酸钙骨水泥组和多孔磷酸钙骨水泥组(P < 0.01)。表明构建的血管化组织工程支架能够实现可靠迅速血管化。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

脂肪干细胞和生物支架应用于牙槽骨修复

背景：各种生理或病理因素导致的牙槽骨的吸收、缺损是口腔临床医学中的常见问题,但目前较常用的修复缺损牙槽骨的方法不能完全满足临床需要。骨组织工程的出现成为修复骨缺损的研究热点。  目的：就脂肪干细胞的来源和应用价值、生物支架的种类及特性、生物支架对种子细胞的影响及脂肪干细胞复合支架用于动物实验的研究等方面作一总结。 方法：应用计算机检索CNKI和Pubmed数据库中1995年1月至2013年4月关于脂肪干细胞、生物支架及骨修复的文章,在标题和摘要中以“脂肪干细胞,分化、增殖和成骨生物支架,牙槽骨,骨组织工程”或“Adipose stem cells,Differentiation、proliferation and Osteogenesis,Biological scaffold,alveolar bone,bone tissue engineering”为检索词进行检索。选择文章内容与脂肪干细胞和生物支架应用于修复骨缺损有关者,同一领域文献则选择近期发表或发表在权威杂志文章。初检得到163篇文献,根据纳入标准选择关于脂肪干细胞和生物支架应用于修复骨缺损的40篇文献进行综述。 结果与结论：脂肪干细胞具有与骨髓基质干细胞相似的分化潜能,因其来源广、易采集、易培养低衰老,成骨分化好和风险小等特点被广泛关注,尤其和生物支架应用于骨修复表现出更好的成骨效果。随着有关各科学的发展牙槽骨缺损的修复有关问题都可以解决,脂肪干细胞和生物支架构建工程骨将是实现真正意义上牙槽骨再生的发展趋势且具有良好的发展前景。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Osteogenic induction of human bone marrow-derived mesenchymal progenitor cells in novel synthetic polymer-hydrogel matrices

The aim of this project was to investigate the in vitro osteogenic potential of human mesenchymal progenitor cells in novel matrix architectures built by means of a three-dimensional bioresorbable synthetic framework in combination with a hydrogel. Human mesenchymal progenitor cells (hMPCs) were isolated from a human bone marrow aspirate by gradient centrifugation. Before in vitro engineering of scaffold-hMPC constructs, the adipogenic and osteogenic differentiation potential was demonstrated by staining of neutral lipids and induction of bone-specific proteins, respectively. After expansion in monolayer cultures, the cells were enzymatically detached and then seeded in combination with a hydrogel into polycaprolactone (PCL) and polycaprolactone-hydroxyapatite (PCL-HA) frameworks. This scaffold design concept is characterized by novel matrix architecture, good mechanical properties, and slow degradation kinetics of the framework and a biomimetic milieu for cell delivery and proliferation. To induce osteogenic differentiation, the specimens were cultured in an osteogenic cell culture medium and were maintained in vitro for 6 weeks. Cellular distribution and viability within three-dimensional hMPC bone grafts were documented by scanning electron microscopy, cell metabolism assays, and confocal laser microscopy. Secretion of the osteogenic marker molecules type I procollagen and osteocalcin was analyzed by semiquantitative immunocytochemistry assays. Alkaline phosphatase activity was visualized by p-nitrophenyl phosphate substrate reaction. During osteogenic stimulation, hMPCs proliferated toward and onto the PCL and PCL-HA scaffold surfaces and metabolic activity increased, reaching a plateau by day 15. The temporal pattern of bone-related marker molecules produced by in vitro tissue-engineered scaffold-cell constructs revealed that hMPCs differentiated better within the biomimetic matrix architecture along the osteogenic lineage.     

基因转染脐带间充质干细胞与丝素蛋白构建组织工程脂肪

背景：目前国内外构建组织工程脂肪的方法并不完善,虽然构建出了脂肪,但效果不理想。 目的：探讨一种新的构建组织工程脂肪的方法,观察携带重组人胰岛素基因慢病毒载体转染的人脐带间充质干细胞与丝素蛋白复合后在Wistar大鼠体内构建组织工程脂肪的能力。 方法：分离培养人脐带间充质干细胞,将携带重组人胰岛素基因慢病毒载体以最适MOI=10转染人脐带间充质干细胞,将转染组与未转染组(对照组)的人脐带间充质干细胞分别接种于丝素蛋白支架,移植于Wistar大鼠背部皮下。移植后12周取材,行荧光原位杂交技术鉴定、组织形态学和扫描电镜观察。 结果与结论：①油红O染色显示,两组移植物均呈阳性,证明移植物已在体内合成为脂肪组织,转染组脂肪样细胞数量明显高于对照组(P < 0.01)。②苏木精-伊红染色显示,两组移植物组织结构与正常脂肪组织相似,可见明显新生血管。转染组支架材料降解明显,炎性细胞浸润明显少于对照组,新生血管数量也多于对照组。③扫描电镜观察提示,转染组移植物内脂肪样细胞聚集成团,其结构与正常脂肪组织相似;对照组脂肪样细胞散在分布于支架孔隙内。④提示胰岛素基因能明显促进人脐带间充质干细胞成脂肪化,携带重组人胰岛素基因慢病毒载体转染的人脐带间充质干细胞与丝素蛋白支架复合后,在Wistar大鼠体内能构建出组织工程化脂肪组织,其结构类似正常脂肪组织。     

FGF-2 inhibits osteogenesis in mouse adipose tissue-derived stromal cells and sustains their proliferative and osteogenic potential state

In addition to adult bone marrow-derived mesenchymal stem cells, more recently, a second large stromal compartment found in adipose tissue has received attention and is believed to contain multipotent cells. In vitro, adipose tissue-derived stromal cells (ADS) can differentiate down osteogenic, chondrogenic, myogenic, adipose, and even neuronal pathways. In this article, we explore the effect of fibroblast growth factors 2 (FGF-2) on ADS cells. Our results demonstrated that FGF-2 inhibits osteogenesis in ADS cells. The osteogenic inhibitory effects is dose-dependent and reversible, thus suggesting that the lack of osteogenesis observed in ADS cells exposed to FGF-2 is not due to a negative selection triggered by this factor on a subpopulation of osteoblast progenitors. Furthermore, either overexpression of FGF-2, or continuous FGF-2 treatment sustain the proliferative and osteogenic potential state of ADS cells. Therefore, FGF-2 appears to be a positive regulator of osteoprogenitor cells and a negative regulator of osteoblast differentiation in ADS cells. These FGF-2 functional characteristics may assist with cell selection and enrichment for the purpose of bone tissue engineering.     

Paracrine effects influenced by cell culture medium and consequences on microvessel-like structures in cocultures of mesenchymal stem cells and outgrowth endothelial cells

Mesenchymal stem cells (MSC) from bone marrow and outgrowth endothelial cells (OEC) from peripheral blood are considered as attractive cell types for applications in regenerative medicine aiming to build up complex vascularized tissue-engineered constructs. MSC provide several advantages such as the potential to differentiate to osteoblasts and to support the neovascularization process by release of proangiogenic factors. On the other hand, the neovascularization process can be actively supported by OEC forming perfused vascular structures after co-implantation with other cell types. In this study the formation of angiogenic structures in vitro was investigated in cocultures of MSC and OEC, cultured either in the medium for osteogenic differentiation of MSC (ODM) or in the medium for OEC cultivation endothelial cell growth medium-2 (EGM2 Bullet Kit). After 2 weeks, cocultures in EGM2 formed more microvessel-like structures compared to cocultures in ODM as demonstrated by immunofluorescence staining for the endothelial marker CD31. Increased expression of CD31 and CD146 in quantitative real-time polymerase chain reaction as well as a higher percentage of CD31- and CD146-positive cells in flow cytometry indicated a beneficial influence of EGM2 on endothelial cell growth and function. In addition, the improved formation of vascular structures in EGM2 correlates with higher levels of the proangiogenic factor vascular endothelial growth factor and platelet-derived growth factor in the supernatant of cocultures as well as in monocultures of MSC when cultivated in EGM-2. Nevertheless, ODM was more suitable for the differentiation of MSC to osteoblastic lineages in the cocultures, whereas EGM2 favored factors involved in vessel stabilization by pericytes. In conclusion, this study highlights the importance of medium components for cell interaction triggering the formation of angiogenic structures.     

微渠多孔羟基磷灰石支架诱导骨髓间充质干细胞成骨分化的miRNA表达谱分析

文题释义： 羟基磷灰石：是目前最为理想的生物活性材料,具有生物相容性、骨传导性和骨诱导性,植入人体后对组织无刺激和排斥作用,能与骨形成很强的化学结合,用作骨缺损的充填材料,能为新骨的形成提供支架,发挥骨传导作用,是理想的硬组织替代材料。 MicroRNA(miRNA)：是一类内生的、长度为20-24个核苷酸的单链小分子RNA,由具有发夹结构的70-90个碱基大小的单链RNA前体经过Dicer酶加工后生成,其可以通过几个miRNAs的组合在转录后水平精细调控基因的表达。 背景：多孔羟基磷灰石支架具有良好的体内外成骨效能,但其所涉及的miRNAs复杂调控机制相关研究较少。 目的：探讨多孔羟基磷灰石支架材料介导大鼠骨髓间充质干细胞成骨矿化过程中相关miRNA表达谱的变化。 方法：体外分离、培养和鉴定大鼠骨髓间充质干细胞,将骨髓间充质干细胞与多孔羟基磷灰石支架共培养为实验组,骨髓间充质干细胞单独培养为空白对照组,分别进行成骨诱导7 d,运用miRNA高通量测序技术分析两组骨髓间充质干细胞成骨矿化过程中相关miRNA表达谱的变化并进行GO分析,筛选出两组中表达差异明显的miRNA分子并进行qRT-PCR验证。 结果与结论：①与空白对照组比较,成骨诱导7 d时实验组BMP2、ALP、Runx2 mRNA表达上调,其中BMP2上调明显(P < 0.05);②microRNA高通量测序结果显示miR-210-3p、miR-146a-5p等13个miRNAs明显上调;let-7c-3p、let-3615等17个miRNAs明显下调;③GO分析上调的miRNA靶基因主要参与生物学调节、细胞基因表达、基因表达调节等,包括NF-κB、Toll样受体9、细胞间黏附、白细胞介素1调节、血管生成、Hippo等信号通路;④实时荧光定量qPCR验证结果显示miRNA-210在实验组上调15倍,miR-146a-5p在实验组上调10倍(P < 0.05);⑤结果表明,新型微渠多孔羟基磷灰石支架可以通过上调骨髓间充质干细胞miRNA-210-3p和miR-146a表达,促进骨髓间充质干细胞的成骨分化。 ORCID: 0000-0002-8722-1548(郑佳俊) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程