Review of biophysical factors affecting osteogenic differentiation of human adult adipose-derived stem cells

Developing bone is subject to the control of a broad variety of influences in vivo. For bone repair applications, in vitro osteogenic assays are routinely used to test the responses of bone-forming cells to drugs, hormones, and biomaterials. Results of these assays are used to predict the behavior of bone-forming cells in vivo. Stem cell research has shown promise for enhancing bone repair. In vitro osteogenic assays to test the bone-forming response of stem cells typically use chemical solutions. Stem cell in vitro osteogenic assays often neglect important biophysical cues, such as the forces associated with regular weight-bearing exercise, which promote bone formation. Incorporating more biophysical cues that promote bone formation would improve in vitro osteogenic assays for stem cells. Improved in vitro osteogenic stimulation opens opportunities for “pre-conditioning” cells to differentiate towards the desired lineage. In this review, we explore the role of select biophysical factors—growth surfaces, tensile strain, fluid flow and electromagnetic stimulation—in promoting osteogenic differentiation of stem cells from human adipose. Emphasis is placed on the potential for physical microenvironment manipulation to translate tissue engineering and stem cell research into widespread clinical usage.     

Passage-restricted differentiation potential of mesenchymal stem cells into cardiomyocyte-like cells

Mesenchymal stem cells (MSCs) have limited ability to differentiate into cardiomyocytes and the factors affect this process are not fully understood. In this study, we investigated the passage (P)-related transdifferentiation potential of MSCs into cardiomyocyte-like cells and its relationship to the proliferation ability. After 5-azacytidine treatment, only P4 but not P1 and P8 rat bone marrow MSCs (rMSCs) showed formation of myotube and expressed cardiomyocyte-associated markers. The growth property analysis showed P4 rMSCs had a growth-arrest appearance, while P1 and P8 rMSCs displayed an exponential growth pattern. When the rapid proliferation of P1 and P8 rMSCs was inhibited by 5-bromo-2-deoxyuridine, a mitosis inhibitor, only P1, not P8 rMSCs, differentiated into cardiomyocyte-like cells after 5-azacytidine treatment. These results demonstrate that the differentiation ability of rMSCs into cardiomyocytes is in proliferation ability-dependent and passage-restricted patterns. These findings reveal a novel regulation on the transdifferentiation of MSCs and provide useful information for exploiting the clinical therapeutic potential of MSCs.     

Role of human amnion-derived mesenchymal stem cells in promoting osteogenic differentiation by influencing p38 MAPK signaling in lipopolysaccharide -induced human bone marrow mesenchymal stem cells

Periodontitis is a chronic inflammatory disease induced by bacterial pathogens, which not only affect connective tissue attachments but also cause alveolar bone loss. In this study, we investigated the anti-inflammatory effects of Human amnion-derived mesenchymal stem cells (HAMSCs) on human bone marrow mesenchymal stem cells (HBMSCs) under lipopolysaccharide (LPS)-induced inflammatory conditions. Proliferation levels were measured by flow cytometry and immunofluorescence staining of 5-ethynyl-2′-deoxyuridine (EdU). Osteoblastic differentiation and mineralization were investigated using chromogenic alkaline phosphatase activity (ALP) activity substrate assays, Alizarin red S staining, and RT-PCR analysis of HBMSCs osteogenic marker expression. Oxidative stress induced by LPS was investigated by assaying reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity. Here, we demonstrated that HAMSCs increased the proliferation, osteoblastic differentiation, and SOD activity of LPS-induced HBMSCs, and down-regulated the ROS level. Moreover, our results suggested that the activation of p38 MAPK signal transduction pathway is essential for reversing the LPS-induced bone-destructive processes. SB203580, a selective inhibitor of p38 MAPK signaling, significantly suppressed the anti-inflammatory effects in HAMSCs. In conclusion, HAMSCs show a strong potential in treating inflammation-induced bone loss by influencing p38 MAPK signaling.     

Effects of various antimicrobial agents on multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells

Antimicrobial drugs of several classes play an important role in the treatment of bone and joint infections. In addition to fighting pathogenic microorganisms, the effects of drugs on local tissues and cells are also related to the course and prognosis of bone and joint infections. The multi-directional differentiation potential of bone marrow-derived mesenchymal stem cells (MSCs) is essential for tissue repair after local injury, which is directly related to the recovery of bone, cartilage, and medullary adipose tissue. Our previous studies and the literature indicate that certain antimicrobial agents can regulate the differentiation potential of bone marrow-derived MSCs. Here, in order to systematically analyze the effects of various antimicrobial drugs on local tissue regeneration, we comprehensively review the studies on the effects of these drugs on MSC differentiation, and classify them according to the three differentiation directions (osteogenesis, chondrogenesis, and adipogenesis). Our review demonstrates the specific effects of different antimicrobial agents on bone marrow-derived MSCs and the range of concentrations at which they work, and provides a basis for drug selection at different sites of infection.     

Involvement of PTP-RQ in differentiation during adipogenesis of human mesenchymal stem cells

Mesenchymal stem cells (MSCs) are self-renewable multipotent progenitor cells with the capacity to differentiate into several distinct mesenchymal lineages. While MSCs display significant potential in tissue engineering and therapeutic applications, the regulatory mechanisms underlying the differentiation of these cells are yet to be established. Phosphorylation is a post-translational modification that plays a significant role in diverse biological phenomena. In this study, to mine the protein tyrosine phosphatases (PTPs) involved in adipogenesis of human MSCs, differential expression of human PTPs was examined using RT-PCR analysis. Among the 107 human PTPs, PTP-RQ was dramatically downregulated during the early phase of adipogenesis. PTP-RQ is classified as a receptor-type III PTP with phosphatidylinositol phosphatase (PIPase) activity. Overexpression of PTP-RQ consistently led to reduced differentiation of MSCs into adipocytes via decreasing the phosphatidyl inositol phosphate level in cells, and consequently downregulating Akt/PKB phosphorylation. Our results collectively suggest that PTP-RQ is a useful target protein for regulating the differentiation of MSCs into adipocytes, and may be used to develop novel drugs for the treatment of obesity.     

Osteogenic potential: comparison between bone marrow and adipose-derived mesenchymal stem cells

Bone tissue engineering(BTE) is now a promising re-search issue to improve the drawbacks from traditional bone grafting procedure such as limited donor sources and possible complications. Stem cells are one of the major factors in BTE due to the capability of self re-newal and multi-lineage differentiation. Unlike embry-onic stem cells, which are more controversial in ethical problem, adult mesenchymal stem cells are considered to be a more appropriate cell source for BTE. Bone marrow mesenchymal stem cells(BMSCs) are the ear-liest-discovered and well-known stem cell source using in BTE. However, the low stem cell yield requiring long expansion time in vitro, pain and possible morbidities during bone marrow aspiration and poor proliferation and osteogenic ability at old age impede its' clinical ap-plication. Afterwards, a new stem cell source coming from adipose tissue, so-called adipose-derived stemcells(ASCs), is found to be more suitable in clinical ap-plication because of high stem cells yield from lipoaspi-rates, faster cell proliferation and less discomfort and morbidities during harvesting procedure. However, the osteogenic capacity of ASCs is now still debated be-cause most papers described the inferior osteogenesis of ASCs than BMSCs. A better understanding of the osteogenic differences between ASCs and BMSCs is crucial for future selection of cells in clinical application for BTE. In this review, we describe the commonality and difference between BMSCs and ASCs by cell yield, cell surface markers and multiple-differentiation poten-tial. Then we compare the osteogenic capacity in vitro and bone regeneration ability in vivo between BMSCs and ASCs based on the literatures which utilized both BMSCs and ASCs simultaneously in their articles. The outcome indicated both BMSCs and ASCs exhibited the osteogenic ability to a certain extent both in-vitro and in-vivo. However, most in-vitro study papers verified the inferior osteogenesis of ASCs; conversely, in-vivo research reviews revealed more controversies in this issue. We expect the new researchers can have a quick understanding of the progress in this filed and design a more comprehensive research based on this review.     

骨髓间充质干细胞向神经细胞分化的研究

无论是在体外实验、还是在体内实验,MSCs都可以向中枢神经系统(CNS)神经细胞分化,但争议颇多。因为功能性神经元不仅要具有典型神经元的形态、特异性标记,还要求具有可兴奋性、能和其他神经元形成突触联系、产生突触电位等,所以对于骨髓间充质干细胞是否能诱导出真正具有功能的神经元存在很大分歧。在此对MSCs向神经细胞诱导分化研究的现况、存在的问题及发展前景给以综述。     

Pulsed electromagnetic fields accelerate proliferation and osteogenic gene expression in human bone marrow mesenchymal stem cells during osteogenic differentiation

Osteogenesis is a complex series of events involving the differentiation of mesenchymal stem cells to generate new bone. In this study, we examined the effect of pulsed electromagnetic fields (PEMFs) on cell proliferation, alkaline phosphatase (ALP) activity, mineralization of the extracellular matrix, and gene expression in bone marrow mesenchymal stem cells (BMMSCs) during osteogenic differentiation. Exposure of BMMSCs to PEMFs increased cell proliferation by 29.6% compared to untreated cells at day 1 of differentiation. Semi‐quantitative RT‐PCR indicated that PEMFs significantly altered temporal expression of osteogenesis‐related genes, including a 2.7‐fold increase in expression of the key osteogenesis regulatory gene cbfa1, compared to untreated controls. In addition, exposure to PEMFs significantly increased ALP expression during the early stages of osteogenesis and substantially enhanced mineralization near the midpoint of osteogenesis. These results suggest that PEMFs enhance early cell proliferation in BMMSC‐mediated osteogenesis, and accelerate the osteogenesis. Bioelectromagnetics 31:209–219, 2010. © 2009 Wiley‐Liss, Inc.     

Ex vivo expansion, adipogenesis and neurogenesis of cryopreserved human bone marrow mesenchymal stem cells

This study aimed to investigate the potentials of ex vivo expansion and pluridifferentiation of cryopreserved adult human bone marrow mesenchymal stem cells (hMSCs) into adipocytes and neurocytes. Cryopreserved hMSCs were resuscitated and cultured for 15 passages, and then induced to adipocytes and neurocytes with corresponding induction medium. The induced cells were observed for morphological properties and expression of triglyceride or neuron-specific enolase and nestin was detected. The result showed that the resuscitated cells cultured in induction medium consisting of dexamethasone, 3-isobutyl-1-methylxanthine, indomethacin and insulin-like growth factor I (IGF-I) showed adipogenesis, and lipid vacuole accumulation was detectable after 21days. The resuscitated hMSCs were also induced into neurocytes and expressed nestin and neuron-specific enolase (NSE), which are special surface markers associated with neural cells at different stages. This study suggested that resuscitated hMSCs should still be a population of pluripotential cells and should be accessible for establishing an abundant hMSC reservoir for further experiment and treatment of various clinical diseases.     

Effects of miR-31 on the osteogenesis of human mesenchymal stem cells

Exploring the molecular mechanisms that regulate the osteogenesis of human mesenchymal stem cells (hMSCs) will bring us more efficient methods for improving the treatment of bone-related diseases. In this study, we analyzed the effects of miR-31 on the osteogenesis of hMSCs. The overexpression of miR-31 repressed the osteogenesis of hMSCs, whereas the downregulation enhanced this process. SATB2 was testified to be a direct target of miR-31, and its effects on the osteogenesis were also described. Most importantly, the knockdown of SATB2 attenuated miR-31’s osteogenic effects. Taken together, our findings suggest that miR-31 regulates the osteogenesis of hMSCs by targeting SATB2.     

猪脂肪间充质干细胞的分离培养及其成脂分化

脂肪间充质干细胞(Adipose mesenchymal stemcell,AMSCs)是一类来源于脂肪组织并具有多向分化潜能的干细胞。近年来的研究证明,脂肪组织具有取材方便和干细胞含量高的优势,有望在研究与应用领域成为骨髓干细胞的替代物。猪是一种比啮齿类更接近人类的模式动物,具有较强的脂肪沉积能力。本研究探讨了猪脂肪间充质干细胞的体外分离纯化、培养扩增和向脂肪细胞诱导分化的条件。采用Ⅰ型胶原酶消化分离脂肪微管基质成分,传代培养扩增,流式细胞仪检测细胞表面标记。取第3-7代AMSCs,采用不同方法诱导AMSCs向脂肪细胞分化,光学显微镜下可观察到诱导后的细胞内有高折光性的小脂滴出现,油红O染色成阳性,不同诱导方法诱导率不同。被诱导细胞用RT-PCR可检测到脂肪细胞分化标志基因LPL和PPARγ的表达。结果表明可以从脂肪组织中分离培养出AMSCs,经传代后可提高其纯度。CD44、CD105表达呈阳性,CD14、CD34、S-100、HLA-DR呈阴性,在合适的诱导条件下,可向脂肪细胞分化。     

Enhancing survival,engraftment, and osteogenic potential of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are promising candidates for bone regeneration therapies due to their plasticity and easiness of sourcing. MSC-based treatments are generally considered a safe procedure, however, the long-term results obtained up to now are far from satisfactory. The main causes of these therapeutic limitations are inefficient homing, engraftment, and osteogenic differentiation. Many studies have proposed modifications to improve MSC engraftment and osteogenic differentiation of the transplanted cells. Several strategies are aimed to improve cell resistance to the hostile microenvironment found in the recipient tissue and increase cell survival after transplantation. These strategies could range from a simple modification of the culture conditions, known as cell-preconditioning, to the genetic modification of the cells to avoid cellular senescence. Many efforts have also been done in order to enhance the osteogenic potential of the transplanted cells and induce bone formation, mainly by the use of bioactive or biomimetic scaffolds, although alternative approaches will also be discussed. This review aims to summarize several of the most recent approaches, providing an up-to-date view of the main developments in MSC-based regenerative techniques.     

Calcium phosphate surfaces promote osteogenic differentiation of mesenchymal stem cells

Although studies in vivo revealed promising results in bone regeneration after implantation of scaffolds together with osteogenic progenitor cells, basic questions remain how material surfaces control the biology of mesenchymal stem cells (MSC). We used human MSC derived from bone marrow and studied the osteogenic differentiation on calcium phosphate surfaces. In osteogenic differentiation medium MSC differentiated to osteoblasts on hydroxyapatite and BONITmatrix, a degradable xerogel composite, within 14 days. Cells revealed a higher alkaline phosphatase (ALP) activity and increased RNA expression of collagen I and osteocalcin using real-time RTPCR compared with cells on tissue culture plastic. To test whether material surface characteristics alone are able to stimulate osteogenic differentiation, MSC were cultured on the materials in expansion medium without soluble additives for osteogenic differentiation. Indeed, cells on calcium phosphate without osteogenic differentiation additives developed to osteoblasts as shown by increased ALP activity and expression of osteogenic genes, which was not the case on tissue culture plastic. Because we reasoned that the stimulating effect on osteogenesis by calcium phosphate surfaces depends on an altered cell-extracellular matrix interaction we studied the dynamic behaviour of focal adhesions using cells transfected with GFP labelled vinculin. On BONITmatrix, an increased mobility of focal adhesions was observed compared with cells on tissue culture plastic. In conclusion, calcium phosphate surfaces are able to drive MSC to osteoblasts in the absence of osteogenic differentiation supplements in the medium. An altered dynamic behaviour of focal adhesions on calcium phosphate surfaces might be involved in the molecular mechanisms which promote osteogenic differentiation.     

miR-140-5p suppresses BMP2-mediated osteogenesis in undifferentiated human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) have self-renewal and differentiation capabilities but the regulatory mechanisms of MSC fate determination remain poorly understood. Here, we aimed to identify microRNAs enriched in hMSCs that modulate differentiation commitments. Microarray analysis revealed that miR-140-5p is commonly enriched in undifferentiated hMSCs from various tissue sources. Moreover, bioinformatic analysis and luciferase reporter assay validated that miR-140-5p directly represses bone morphogenic protein 2 (BMP2). Furthermore, blocking miR-140-5p in hMSCs increased the expression of BMP signaling components and critical regulators of osteogenic differentiation. We propose that miR-140-5p functionally inhibits osteogenic lineage commitment in undifferentiated hMSCs.     

Role of gangliosides in the differentiation of human mesenchymal-derived stem cells into osteoblasts and neuronal cells

Gangliosides are complex glycosphingolipids that are the major component of cytoplasmic cell membranes, and play a role in the control of biological processes. Human mesenchymal stem cells (hMSCs) have received considerable attention as alternative sources of adult stem cells because of their potential to differentiate into multiple cell lineages. In this study, we focus on various functional roles of gangliosides in the differentiation of hMSCs into osteoblasts or neuronal cells. A relationship between gangliosides and epidermal growth factor receptor (EGFR) activation during osteoblastic differentiation of hMSCs was observed, and the gangliosides may play a major role in the regulation of the differentiation. The roles of gangliosides in osteoblast differentiation are dependent on the origin of hMSCs. The reduction of ganglioside biosynthesis inhibited the neuronal differentiation of hMSCs during an early stage of the differentiation process, and the ganglioside expression can be used as a marker for the identification of neuronal differentiation from hMSCs. [BMB Reports 2013; 46(11): 527-532]     

The simulated microgravity enhances multipotential differentiation capacity of bone marrow mesenchymal stem cells

Multi-differentiation capability is an essential characteristic of bone marrow mesenchymal stem cells (BMSCs). Method on obtaining higher-quality stem cells with an improved differentiation potential has gained significant attention for the treatment of clinical diseases and developmental biology. In our study, we investigated the multipotential differentiation capacity of BMSCs under simulated microgravity (SMG) condition. F-actin staining found that cytoskeleton took on a time-dependent change under SMG condition, which caused spindle to round morphological change of the cultured cells. Quantitative PCR and Western Blotting showed the pluripotency marker OCT4 was up-regulated in the SMG condition especially after SMG of 72 h, which we observed would be the most appropriate SMG duration for enhancing pluripotency of BMSCs. After dividing BMSCs into normal gravity (NG) group and SMG group, we induced them respectively in endothelium oriented, adipogenic and neuronal induction media. Immunostaining and Western Blotting found that endothelium oriented differentiated BMSCs expressed higher VWF and CD31 in the SMG group than in the NG group. The neuron-like cells derived from BMSCs in the SMG group also expressed higher level of MAP2 and NF-H. Furthermore, the quantity of induced adipocytes increased in the SMG group compared to the NG group shown by Oil Red O staining, The expression of PPARγ2 increased significantly under SMG condition. Therefore, we demonstrated that SMG could promote BMSCs to differentiate into many kinds of cells and predicted that enhanced multi-potential differentiation capacity response in BMSCs following SMG might be relevant to the changes of cytoskeleton and the stem cell marker OCT4.