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.     

调控骨髓间充质干细胞成骨分化的Wnt/β-catenin信号通路及相关因素

背景:骨髓间充质干细胞诱导成骨而抑制成脂分化是骨质疏松症防治的关键,也是骨组织修复工程种子细胞的来源,Wnt信号通路对骨形成起着重要作用.目的:综述Wnt/β-catenin信号通路调控骨髓间充质干细胞成骨分化的相关因素及分子机制.方法:应用计算机检索CNKI、PubMed及万方医学数据库建库至2020年2月发表的相关...     

In vitro evaluation of electrospun silk fibroin/nano-hydroxyapatite/BMP-2 scaffolds for bone regeneration

Bone tissue engineering by using osteoinductive scaffolds seeded with stem cells to promote bone extracellular matrix (ECM) production and remodeling has evolved into a promising approach for bone repair and regeneration. In order to mimic the ECM of bone tissue structurally and compositionally, nanofibrous silk fibroin (SF) scaffolds containing hydroxyapatite (HAP) nanoparticles and bone morphogenetic protein 2 (BMP-2) were fabricated in this study using electrospinning technique. The microstructure, mechanical property, biocompatibility, and osteogenic characteristics were examined. It was found that the HAP nanoparticles were successfully incorporated in the SF nanofibers (diameter, 200–500 nm). The mechanical properties of SF/HAP/BMP-2 composite scaffolds increased with HAP content when it was less than 20 wt%, after which the mechanical properties dropped as HAP content increased. Cell culture tests using bone marrow mesenchymal stem cells (BMSCs) showed that the scaffolds had good biocompatibility and promoted the osteogenic differentiation of BMSCs. Therefore, the electrospun SF/HAP/BMP-2 scaffolds may serve as a promising biomaterial for bone tissue engineering.     

Comparison of immunological properties of bone marrow stromal cells and adipose tissue-derived stem cells before and after osteogenic differentiation in vitro

Mesenchymal stem cells (MSCs) can be isolated from various tissues and represent an attractive cell population for tissue-engineering purposes. MSCs from bone marrow (bone marrow stromal cells [BMSCs]) are negative for immunologically relevant surface markers and inhibit proliferation of allogenic T cells in vitro. Therefore, BMSCs are said to be available for allogenic cell therapy. Although the immunological characteristics of BMSCs have been the subject of various investigations, those of stem cells isolated from adipose tissue (ASCs) have not been adequately described. In addition, the influence of osteogenic differentiation in vitro on the immunological characteristics of BMSCs and ASCs is the subject of this article. Before and after osteogenic induction, the influence of BMSCs and ASCs on the proliferative behavior of resting and activated allogenic peripheral blood mononuclear cells (PBMCs) was studied as a measure of the immune response (mixed lymphocyte culture). At the same points, the expression of immunologically relevant surface markers (e.g., major histocompatibility complex (MHC)-I, MHC-II, CD40, CD40L) was measured, and correlations between the different sets of results were sought. The pattern of surface antigen expression of BMSCs is the same as that of ASCs. Analogous to BMSCs, undifferentiated cells isolated from adipose tissue lack expression of MHC-II; this is not lost in the course of the osteogenic differentiation process. In co-culture with allogenic PBMCs, both cell types fail to lead to any significant stimulation, and they both retain these characteristics during the differentiation process. BMSCs and ASCs suppress proliferation on activated PBMCs before and after osteogenic differentiation. Our results confirm that MSCs are immune modulating cells. These properties are retained even after osteogenic induction in vitro and seem to be similar in BMSCs and ASCs. Our results suggest that allogenic transplantation of BMSCs and ASCs would be possible, for example, in the context of tissue engineering.     

Multilineage cells from human adipose tissue: implications for cell-based therapies

Future cell-based therapies such as tissue engineering will benefit from a source of autologous pluripotent stem cells. For mesodermal tissue engineering, one such source of cells is the bone marrow stroma. The bone marrow compartment contains several cell populations, including mesenchymal stem cells (MSCs) that are capable of differentiating into adipogenic, osteogenic, chondrogenic, and myogenic cells. However, autologous bone marrow procurement has potential limitations. An alternate source of autologous adult stem cells that is obtainable in large quantities, under local anesthesia, with minimal discomfort would be advantageous. In this study, we determined if a population of stem cells could be isolated from human adipose tissue. Human adipose tissue, obtained by suction-assisted lipectomy (i.e., liposuction), was processed to obtain a fibroblast-like population of cells or a processed lipoaspirate (PLA). These PLA cells can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of PLA cells are of mesodermal or mesenchymal origin with low levels of contaminating pericytes, endothelial cells, and smooth muscle cells. Finally, PLA cells differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, the data support the hypothesis that a human lipoaspirate contains multipotent cells and may represent an alternative stem cell source to bone marrow-derived MSCs.     

Ectopic bone regeneration by human bone marrow mononucleated cells, undifferentiated and osteogenically differentiated bone marrow mesenchymal stem cells in beta-tricalcium phosphate scaffolds

Tissue engineering approaches using the combination of porous ceramics and bone marrow mesenchymal stem cells (BMSCs) represent a promising bone substitute for repairing large bone defects. Nevertheless, optimal conditions for constructing tissue-engineered bone have yet to be determined. It remains unclear if transplantation of predifferentiated BMSCs is superior to undifferentiated BMSCs or freshly isolated bone marrow mononucleated cells (BMNCs) in terms of new bone formation in vivo. The aim of this study was to investigate the effect of in vitro osteogenic differentiation (β-glycerophosphate, dexamethasone, and l-ascorbic acid) of human BMSCs on the capability to form tissue-engineered bone in unloaded conditions after subcutaneous implantation in nude mice. After isolation from human bone marrow aspirates, BMNCs were divided into three parts: one part was seeded onto porous beta-tricalcium phosphate ceramics immediately and transplanted in a heterotopic nude mice model; two parts were expanded in vitro to passage 2 before cell seeding and in vivo transplantation, either under osteogenic conditions or not. Animals were sacrificed for micro-CT and histological evaluation at 4, 8, 12, 16, and 20 weeks postimplantation. The results showed that BMSCs differentiated into osteo-progenitor cells after induction, as evidenced by the altered cell morphology and elevated alkaline phosphatase activity and calcium deposition, but their clonogenicity, proliferating rate, and seeding efficacy were not significantly affected by osteogenic differentiation, compared with undifferentiated cells. Extensive new bone formed in the pores of all the scaffolds seeded with predifferentiated BMSCs at 4 weeks after implantation, and maintained for 20 weeks. On the contrary, scaffolds containing undifferentiated BMSCs revealed limited bone formation only in 1 out of 6 cases at 8 weeks, and maintained for 4 weeks. For scaffolds with BMNCs, woven bone was observed sporadically only in one case at 8 weeks. Overall, this study suggests that ectopic osteogenesis of cell/scaffold composites is more dependent on the in vitro expansion condition, and osteo-differentiated BMSCs hold the highest potential concerning in vivo bone regeneration.     

The effects of platelet-rich plasma on the osteogenic induction of bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) are multipotent stem cells. Finding methods to improve the osteogenic potential of these cells is a key factor in bone tissue engineering. Platelet-rich plasma (PRP) contains powerful growth factors that produce changes in a variety of cell types. The purpose of this study was to explore the effects of PRP on the osteogenic differentiation of BMSCs in vitro. Rabbit BMSCs were harvested and cultured in vitro in control media or in media enhanced with PRP. BMSCs began to attach 12–24 hours after seeding. A MTT assay demonstrated that PRP-induced BMSCs grew rapidly compared with the control group. The PRP group also showed strongly positive staining of alkaline phosphatase and mineralized nodules whereas the control group showed negative staining. However, the alkaline phosphatase activity and the mRNA level of the osteogenic markers (osteocalcin and osteopontin) remained higher in the PRP group. These results confirmed that PRP could enhance the proliferation of BMSCs and effectively promote the osteogenic differentiation of BMSCs in vitro.     

脱细胞随机肌腱支架促进骨髓间充质干细胞骨向分化

目的:探究随机肌腱细胞外基质(ECM)支架对骨髓间充质干细胞(BMSCs)活力和分化的影响。方法:从Sprague-Dawley大鼠股骨和胫骨中提取BMSCs,体外培养,观察细胞形态,并利用流式细胞术鉴定细胞干性。采用1%Triton X-100和DNase/RNase混合液对鼠尾肌腱进行脱细胞处理,利用HE染色和DNA含量测定考察肌腱组织中细胞核残余情况。制备胶原纤维随机排列的肌腱ECM支架,培养BMSCs,以孔板中生长的细胞为对照组,利用Live/Dead染色和CCK8法考察细胞的活力和形态;利用RT-qPCR检测肌腱标志物I型胶原蛋白(Col I)、肌腱特异转录因子scleraxis(SCX)及成骨标志物碱性磷酸酶(ALP)和Runt相关转录因子2(RUNX2)的表达水平。结果:HE染色结果显示,经过脱细胞处理后肌腱组织内无细胞残余,且DNA含量从(481.7±15.8)μg/g显著性降至(31.0±3.8)μg/g(P<0.05),脱细胞处理成功。7 d时,种植在支架上的BMSCs的活力较对照组显著增强(P<0.05);14 d时,种植在支架上的BMSCs肌腱标志物Col I和SCX的表达量较对照组显著下调,而成骨标志物ALP和RUNX2的表达量较对照组显著上调(P<0.05)。结论:脱细胞随机肌腱ECM支架能增强BMSCs活力,并诱导其向成骨细胞分化。     

Autocrine fibroblast growth factor 2 increases the multipotentiality of human adipose-derived mesenchymal stem cells

Multipotent mesenchymal stem cells (MSCs), first identified in the bone marrow, have subsequently been found in many other tissues, including fat, cartilage, muscle, and bone. Adipose tissue has been identified as an alternative to bone marrow as a source for the isolation of MSCs, as it is neither limited in volume nor as invasive in the harvesting. This study compares the multipotentiality of bone marrow-derived mesenchymal stem cells (BMSCs) with that of adipose-derived mesenchymal stem cells (AMSCs) from 12 age- and sex-matched donors. Phenotypically, the cells are very similar, with only three surface markers, CD106, CD146, and HLA-ABC, differentially expressed in the BMSCs. Although colony-forming units-fibroblastic numbers in BMSCs were higher than in AMSCs, the expression of multiple stem cell-related genes, like that of fibroblast growth factor 2 (FGF2), the Wnt pathway effectors FRAT1 and frizzled 1, and other self-renewal markers, was greater in AMSCs. Furthermore, AMSCs displayed enhanced osteogenic and adipogenic potential, whereas BMSCs formed chondrocytes more readily than AMSCs. However, by removing the effects of proliferation from the experiment, AMSCs no longer out-performed BMSCs in their ability to undergo osteogenic and adipogenic differentiation. Inhibition of the FGF2/fibroblast growth factor receptor 1 signaling pathway demonstrated that FGF2 is required for the proliferation of both AMSCs and BMSCs, yet blocking FGF2 signaling had no direct effect on osteogenic differentiation. Disclosure of potential conflicts of interest is found at the end of this article.     

The Nell-1 growth factor stimulates bone formation by purified human perivascular cells

The search for novel sources of stem cells other than bone marrow mesenchymal stem cells (MSCs) for bone regeneration and repair has been a critical endeavor. We previously established an effective protocol to homogeneously purify human pericytes from multiple fetal and adult tissues, including adipose, bone marrow, skeletal muscle, and pancreas, and identified pericytes as a primitive origin of human MSCs. In the present study, we further characterized the osteogenic potential of purified human pericytes combined with a novel osteoinductive growth factor, Nell-1. Purified pericytes grown on either standard culture ware or human cancellous bone chip (hCBC) scaffolds exhibited robust osteogenic differentiation in vitro. Using a nude mouse muscle pouch model, pericytes formed significant new bone in vivo as compared to scaffold alone (hCBC). Moreover, Nell-1 significantly increased pericyte osteogenic differentiation, both in vitro and in vivo. Interestingly, Nell-1 significantly induced pericyte proliferation and was observed to have pro-angiogenic effects, both in vitro and in vivo. These studies suggest that pericytes are a potential new cell source for future efforts in skeletal regenerative medicine, and that Nell-1 is a candidate growth factor able to induce pericyte osteogenic differentiation.     

脂肪与骨髓来源间充质干细胞生物学特性的比较

背景：近几年来脂肪来源的间充质干细胞因其取材容易也被广泛研究。 目的：比较脂肪来源和骨髓来源间充质干细胞的生物学特性。 方法：分离及体外培养人骨髓源间充质干细胞和脂肪源间充质干细胞,比较它们的表型、细胞倍增时间及分泌因子水平等。 结果与结论：脂肪来源和骨髓来源的间充质干细胞在细胞表型上类似,只有CD106的表达有差异。脂肪来源间充质干细胞增殖速率比骨髓来源的间充质干细胞快。在相同体积的脂肪组织中能够得到的干细胞前体细胞的数量是骨髓的10倍以上。提示脂肪来源和骨髓来源的间充质干细胞具有相同功能,但脂肪组织是一个更有应用前景的干细胞来源。     

微重力对骨髓间充质干细胞成骨分化的影响

骨髓间充质干细胞（BMSCs）是一种多能成体于细胞,是组织工程重要的种子细胞来源之一.微重力对BMSCs成骨分化具有抑制作用,可使骨量减少和骨微结构改变,从而导致骨质疏松症.这一过程受到多条信号通路的调控,如MAPK信号通路、Notch信号通路和Wnt/β-catenin信号通路等,它们协同调节微重力下BMSCs向成骨细胞方向的分化.研究微重力对BMSCs成骨分化的影响,可以阐明骨质流失机理,为相关疾病的治疗提供新的靶点,促进我国太空宇航事业的发展.     

体外构建组织工程骨-软骨复合组织

背景：设计一体化、具有过渡结构的双层支架材料,复合软骨细胞、骨髓间充质细胞,有利于新生的骨与软骨组织之间形成良好界面。 目的：模仿自然骨-软骨基质构建复合支架,以软骨细胞和骨髓间充质干细胞为种子细胞,体外观察复合组织的成软骨及成骨能力。 方法：制备明胶-硫酸软骨素-透明质酸及明胶-陶瓷化骨多孔复合支架,构建自然骨-软骨基质复合支架,复合兔软骨细胞与骨髓间充质干细胞,分未成骨诱导与成骨诱导两组培养,并进行MTT、糖胺多糖含量、碱性磷酸酶活性检测,以及苏木精-伊红染色检测。 结果与结论：未成骨诱导与成骨诱导两组骨髓间充质干细胞增殖及糖胺多糖含量差异无显著性意义。未成骨诱导组碱性磷酸酶活性缓慢上升,成骨诱导组诱导后碱性磷酸酶活性迅速上升,14 d时达到稳定状态。两组苏木精-伊红染色结果无明显区别,均已形成含有双层组织的类似骨-软骨样组织,其间可见未降解支架形态,但由于基质形成不完善及支架未完全降解,此种结构不成熟,细胞分布不均匀,支架内部可见散在无细胞区域。证实采用两种细胞与双层结构的支架经体外分层复合能够形成组织工程骨软骨复合组织。     

Mesenchymal Cells of the Deciduous Tooth Pulp: Cytophenotype and Initial Evaluation of Possibility of Their Use in Bone Tissue Engineering

Cultures of mesenchymal cells from human deciduous tooth pulp were derived. The phenotype and capacity to osteogenic and adipogenic differentiation of these cells are close to those of bone marrow mesenchymal stem cells. Deciduous tooth pulp mesenchymal cells populate biodegradable polylactide scaffolds and hence, can be used for the creation of tissue engineering transplants for bone defect repair. Storage of decidual tooth pulp mesenchymal cells in the stem cell cryobanks together with umbilical blood will appreciably extent the periods of age for collection of juvenile autologous stem cells for use throughout the life span.     

Mesenchymal cells of the decidual tooth pulp: cytophenotype and initial evaluation of possibility of their use in bone tissue engineering

Cultures of mesenchymal cells from human decidual tooth pulp were derived. The phenotype and capacity to osteogenic and adipogenic differentiation of these cells are close to those of bone marrow mesenchymal stem cells. Decidual tooth pulp mesenchymal cells populate biodegraded polylactide scaffolds and hence, can be used for the creation of tissue engineering transplants for bone defect repair. Storage of decidual tooth pulp mesenchymal cells in the stem cell cryobanks together with umbilical blood will appreciably extent the periods of age for collection of juvenile autologous stem cells for use throughout the life span.     

大鼠骨髓间充质干细胞的培养与鉴定

背景：骨髓间充质干细胞在骨髓中含量极低,体外培养难度较大。体外分离培养纯度高、活力强、生物特性均一的间充质干细胞,对组织工程及细胞的体内、体外实验显得至关重要。 目的：建立大鼠骨髓间充质干细胞的分离、培养、纯化方法,并进行细胞形态学观察、表面标志物鉴定及多向分化能力检测。 方法：通过全骨髓贴壁法体外分离、培养、纯化大鼠骨髓间充质干细胞,进行形态学观察,绘制生长曲线,细胞周期分析,流式细胞仪检测细胞表面标记物,分别向成骨、成脂方向诱导分化。 结果与结论：大鼠骨髓间充质干细胞生长以梭形细胞为主,呈放射状排列的细胞集落,细胞生长旺盛,可连续稳定传代10代以上。生长曲线及细胞周期显示骨髓间充质干细胞符合正常细胞生长特征且生长活跃。第3代骨髓间充质干细胞CD44,CD90,CD105均呈阳性表达,而CD34,CD45呈阴性表达。成脂、成骨诱导后,油红O染色、碱性磷酸酶染色、von Kossa法染色和茜素红染色均呈阳性。全骨髓贴壁培养法操作简单,可大量分离、纯化、扩增骨髓间充质干细胞,所获细胞具有间充质干细胞的一般生物学特性,经诱导培养后具有多向分化潜能。实验所用的全骨髓贴壁法法为组织工程提供充足的种子细胞来源具有重要的现实意义。     

Comparison of proliferative and multilineage differentiation potential of human mesenchymal stem cells derived from umbilical cord and bone marrow

Human umbilical cord perivascular cells (HUCPVCs) have been shown to have a high proliferative potential and the capacity to differentiate into an osteogenic phenotype. HUCPVCs have thus been considered a possible extra-embryonic mesenchymal stem cell (MSC) source for cell-based therapies. To assess this potential, we compared HUCPVCs to the "gold standard" bone marrow mesenchymal stromal cells (BMSCs) with respect to their proliferation, differentiation, and transfection capacities. HUCPVCs showed a higher proliferative potential than BMSCs and were capable of osteogenic, chondrogenic, and adipogenic differentiation. Interestingly, osteogenic differentiation of HUCPVCs proceeded more rapidly than BMSCs. Additionally, HUCPVCs expressed higher levels of CD146, a putative MSC marker, relative to BMSCs. HUCPVCs showed comparable transfection efficiency as BMSCs using a nucleofection method but were more amenable to transfection with liposomal methods (FuGENE). Gene array analysis showed that HUCPVCs also expressed Wnt signaling pathway genes that have been implicated in the regulation of MSCs. The similar characteristics between HUCPVCs and MSCs support the applicability of HUCPVCs for cell-based therapies. Disclosure of potential conflicts of interest is found at the end of this article.     

MicroRNA-26a对人骨髓间充质干细胞成骨分化机制在修复骨缺损研究进展

人骨髓间充质干细胞是人体成骨分化的主要骨母干细胞来源,主导人的骨与软骨的再生与重建。近年在研究影响的影响因素上,microRNAs被报道其相关家族在骨髓间充质干细胞的分化过程中起着关键的调节控制作用,其中miRNA-26a在促进骨髓间充质干细胞成骨分化中起着关键作用。microRNA-26a通过影响Smad1、GSK3β、BMP、Id1信号通路增强骨髓间充质干细胞的成骨分化作用,从而促进骨质生成。本综述将阐述microRNAs家族作用于成骨分化的发现,进一步详细阐述microRNA-26a对人骨髓间充质干细胞的作用机制的研究发现和目前miRNA-26a转染骨髓间充质干细胞对修复骨缺损的研究进展。