Osteogenesis Of Adipose-derived Stem Cells Research Articles

Parathyroid hormone (PTH) promotes ADSC osteogenesis by regulating SIK2 and Wnt4

Developing methods for regenerating bones and uncovering the molecular mechanism underlying bone formation have great significance to human health. In the last decade, people have been using adipose-derived stem cells (ADSCs), that are capable of multilineage differentiation, to reconstruct defected bones. Uncovering the molecular mechanisms of the osteoblast differentiation of ADSCs will provide more understanding of ADSCs in the application of bone regeneration and perhaps new methods for osteoporosis treatment. Here we studied how parathyroid hormone (PTH1-34) acts on osteoinduced ADSCs to orchestrate bone formation and how Wnt4 signaling is involved in PTH-promoted bone formation from ADSCs. We found that PTH1-34 can phosphorylate SIK2, upregulate RANKL and downregulate SOST, thereby upregulating Wnt4 to promote the osteogenesis process of ADSCs. Though the knockdown of Wnt4 with shRNA interference barely affects the expression of upstream proteins (i.e., RANKL, SOST), it affects the expression of other downstream osteogenic proteins (i.e., Runx2, Osterix, and Osteocalcin), and then inhibit the osteogenesis process of ADSCs. Overall, PTH can affect the osteogenesis process of ADSCs by regulating SIK2 and Wnt4. We anticipate that this work will provide researchers with new insights into the bone regeneration with ADSCs.

Heparin-Conjugated Decellularized Bone Particles Promote Enhanced Osteogenic Signaling of PDGF-BB to Adipose-Derived Stem Cells in Tissue Engineered Bone Grafts.

Adipose-derived stem cells (ASCs) are a promising cell source for regenerating critical-sized craniofacial bone defects, but their clinical use is limited due to the supraphysiological levels of bone morphogenetic protein-2 required to induce bone formation in large grafts. It has been recently reported that platelet-derived growth factor-BB (PDGF) directly enhances the osteogenesis of ASCs when applied at physiological concentrations. In this study, a biomimetic delivery system that tethers PDGF to decellularized bone matrix (DCB) is developed to enhance osteogenic signaling in bone grafts by colocalizing PDGF-extracellular matrix cues. Heparin is conjugated to DCB particles (HC-DCB) to promote sustained binding of PDGF via electrostatic interactions. HC-DCB particles bind to PDGF with >99% efficiency and release significantly less PDGF over 21 days compared to nonconjugated DCB particles (1.1% vs 22.8%). HC-DCB-PDGF signaling in polycaprolactone (PCL)-fibrin grafts promotes >40 µg Ca2+ µg-1 DNA deposition by ASCs during in vitro osteogenic culture compared to grafts without HC-DCB or PDGF. Furthermore, more bone formation is observed in grafts with HC-DCB-PDGF at 12 weeks following implantation of grafts into murine critical-sized calvarial defects. Collectively, these results demonstrate that HC-DCB enhances the osteogenic signaling of PDGF to ASCs and may be applied to promote ASC-mediated bone regeneration in critical-sized defects.

Magnetic Cell-Scaffold Interface Constructed by Superparamagnetic IONP Enhanced Osteogenesis of Adipose-Derived Stem Cells.

One of the key factors in tissue engineering and regenerative medicine is to optimize the interaction between seed cells and scaffolds such that the cells can grow in naturally biomimetic conditions. Their similarity to macromolecules and many unique properties mean that functional nanoparticles have promising potential for the modification and improvement of traditional scaffolds to obtain excellent biocompatibility, tunable stiffness, physical sensing, and stimulus-response capabilities. In the present study, we report magnetic poly(lactic- co-glycolic acid)/polycaprolactone (PLGA/PCL) scaffolds that were fabricated using a combination of the electrospinning technique and layer-by-layer assembly of superparamagnetic iron oxide nanoparticles (IONPs). PLGA/PCL scaffolds assembled with gold nanoparticles were prepared using the same method for comparison. The results showed that the assembled film of nanoparticles on the surface greatly enhanced the hydrophilicity and increased the elastic modulus of the scaffold, which subsequently improved the osteogenesis of the stem cells. Furthermore, the magnetic property of the IONPs proved to be the key factor in enhancing osteogenic differentiation, which explained the superior osteogenic capacity of the magnetic scaffolds compared with that of the gold nanoparticle-assembled scaffold. These results demonstrated the importance of magnetic nanomaterials as a bioactive interface between cells and scaffolds and will promote the design of biomaterials to improve tissue engineering and regenerative medicine efficacy.

Blockade of receptors of advanced glycation end products ameliorates diabetic osteogenesis of adipose-derived stem cells through DNA methylation and Wnt signalling pathway.

Diabetes mellitus-related osteoporosis is caused by the imbalance between bone absorption and bone formation. Advanced glycation end products (AGEs) are considered a cause of diabetic osteoporosis. Although adipose-derived stem cells (ASCs) are promising adult stem cells in bone tissue regeneration, the ability of osteogenesis of ASCs in diabetic environment needs to explore. This study aimed to investigate the influence of AGEs on the osteogenic potential of ASCs and to explore the signalling pathways involved in its effect. ASCs were isolated from inguinal fat and cultured in osteogenic media with or without AGEs and FPS-ZM1, an inhibitor of receptor for AGEs (RAGE). Alizarin red-S, Oil Red-O and Alcian blue staining were used to confirm osteogenic, adipogenic and chondrogenic potential of ASCs, respectively. Immunofluorescence, western blotting and real-time PCR were used to measure changes in markers of osteogenic differentiation, DNA methylation and Wnt signalling. The multipotentiality of ASCs was confirmed. Treated with AGEs, OPN and RUNX2 expressions of ASCs were reduced and there was a noticeable loss of mineralization, concomitant with an increase in the expression of RAGE, 5-MC, DNMT1 and DNMT3a. AGEs treatment also led to a loss of Wnt signalling pathway markers, including β-Catenin and LEF1, with an increase in GSK-3β. Treatment with the RAGE inhibitor, FPS-ZM1, rescued AGEs-induced loss of osteogenic potential, modulated DNA methylation and upregulated Wnt signalling in ASCs. Our results demonstrate that AGEs-RAGE signalling inhibits the osteogenic potential of ASCs under osteoinductive conditions by modulating DNA methylation and Wnt signalling. FPS-ZM1 can rescue the negative effects of AGEs and provide a possible treatment for bone tissue regeneration in patients with diabetic osteoporosis.

Combination of resveratrol and 5-azacytydine improves osteogenesis of metabolic syndrome mesenchymal stem cells.

Endocrine disorders have become more and more frequently diagnosed in humans and animals. In horses, equine metabolic syndrome (EMS) is characterized by insulin resistance, hyperleptinemia, hyperinsulinemia, inflammation and usually by pathological obesity. Due to an increased inflammatory response in the adipose tissue, cytophysiological properties of adipose derived stem cells (ASC) have been impaired, which strongly limits their therapeutic potential. Excessive accumulation of reactive oxygen species, mitochondria deterioration and accelerated ageing of those cells affect their multipotency and restrict the effectiveness of the differentiation process. In the present study, we have treated ASC isolated from EMS individuals with a combination of 5‐azacytydine (AZA) and resveratrol (RES) in order to reverse their aged phenotype and enhance osteogenic differentiation. Using SEM and confocal microscope, cell morphology, matrix mineralization and mitochondrial dynamics were assessed. Furthermore, we investigated the expression of osteogenic‐related genes with RT‐PCR. We also investigated the role of autophagy during differentiation and silenced PARKIN expression with siRNA. Obtained results indicated that AZA/RES significantly enhanced early osteogenesis of ASC derived from EMS animals. Increased matrix mineralization, RUNX‐2, collagen type I and osteopontin levels were noted. Furthermore, we proved that AZA/RES exerts its beneficial effects by modulating autophagy and mitochondrial dynamics through PARKIN and RUNX‐2 activity.

FAK and BMP-9 synergistically trigger osteogenic differentiation and bone formation of adipose derived stem cells through enhancing Wnt-β-catenin signaling.

Adipose derived stem cells (ADSCs) could undergo osteogenesis via focal adhesion kinase (FAK) and bone morphogenetic protein (BMP) 9 signals, both of which could affect Wnt-β-catenin signal, a signal pathway closely related to ADSCs osteogenesis. It's still enigma whether FAK and BMP-9 contribute to osteogenesis. Here, we examined the effect of FAK on BMP9-inducedosteogenic differentiation, unveiled the possible molecular mechanism underling this process. In the present study, ADSCs were isolated and purified, and cells of passage 3 underwent virus mediated transfection to prepare ADSCs with stable FAK shRNA expression. Cell viability and migration were detected by MTT and transwell assay, respectively. Expression of osteogenic gene, phosphorylation of FAK and GSK were detected by western blot. Osteogenic potential was evaluated by activity of alkaline phosphatase (ALP) and calcium deposition by ALP staining and Alizarin Red S staining. BMP-9 administration promoted ADSCs osteogenesis. Knocking down FAK attenuated this process, inhibited osteogenic proteins expression through Wnt-β-catenin signal. BMP-9 also triggered ADSCs proliferation and migration, and shFAK antagonized such effects too. Although Wnt signal is affected by FAK shRNA, Smad signal remains intact in ADSCs with shFAK. FAK and BMP-9 could cross talk on Wnt signal pathway and promote ADSCs osteogenesis. FAK could participate in BMP-9 induced ADSCs osteogenesis via Wnt signal pathway other than Smads signals (see in graph).

Analysis of the miRNA and mRNA involved in osteogenesis of adipose-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) are bone marrow stromal cells capable of differentiating into different tissue types. Osteoblastic differentiation is a complex process that is critical for bone formation. An increasing number of studies have suggested that microRNAs (miRNAs) may serve important roles in various biological processes, including osteogenesis of MSCs. However, less is known about the participation of particular miRNAs in the osteogenic differentiation of adipose-derived stem cells (ADSCs). In order to identify functional miRNAs and the key genes involved in the osteogenesis of MSCs, the present study reconstructed a global network using data from the National Center for Biotechnology Information Gene Expression Omnibus. Meanwhile, gene ontology and pathway analysis were performed using the Cytoscape plug-in BinGO and the Database for Annotation, Visualization, and Integration Discovery, respectively. An miRNA-mRNA network composed of 72 mRNA and nine miRNA nodes advised by bioinformatics analysis was constructed. These mRNAs and miRNAs were predicted to be involved in the regulation of osteogenic differentiation of ADSCs according to the gene microarray. In the present study, six miRNAs (miR-143-3p, miR-135a-5p, miR-31-5p, miR-22-3p, miR-193b-3p and let-7i-5p) were observed to be highly associated with the osteogenesis of ADSCs, and dihydropyrimidinase like 3 was identified as a novel regulator in this process. These results provide support for further investigations into the management of bone regeneration-associated diseases.

MAPK signaling has stage-dependent osteogenic effects on human adipose-derived stem cells in vitro

ABSTRACTOverview: The use of pro-osteogenic growth factors, such as BMP2, in human adipose-derived stem cell (ASC) osteogenesis is well described. Because these growth factors work via signal transduction pathways, such as the mitogen-activated protein kinase (MAPK) cascade, a study of the relationship between MAPK signaling and ASC osteogenesis was conducted. Materials and Methods: ERK, JNK, and p38MAPK activation were measured in ASCs osteo-induced using either dexamethasone or vitamin D3 and correlated with mineralization. Activation and mineralization were also measured without dexamethasone or using the glucocorticoid, cortisone. The expression of the MAPK phosphatase, MKP1, and its relationship to mineralization was also assessed. The effect of decreasing MAPK activation on mineralization through the use of exogenous inhibitors was examined along with siRNA-knockdown and adenoviral overexpression of ERK1/2. Finally, the effect of ERK1/2 overexpression on ASCs induced on PLGA scaffolds was assessed. Results: ASC mineralization in dexamethasone or vitamin D3-induced ASCs correlated with both increased ERK1/2 and JNK1/2 activation. ASCs induced without dexamethasone also mineralized, with JNK1/2 signaling possibly mediating this event. No link between cortisone induction and MAPK signaling could be ascertained. ASCs treated with ERK, JNK, or p38MAPK inhibitors showed decreased osteogenic gene expression and diminished mineralization. Mineralization levels were also affected by viruses designed to inhibit or augment ERK1/2 expression and activity. Finally, ASC mineralization appeared to be a balance between the MAPK kinase activity and MKP1. Conclusions: It is likely that MAPK signaling plays a significant role in ASC osteogenesis, affecting differentiation in kinase- and stage-specific manners.

Identification and Characterization of Long Non-Coding RNAs in Osteogenic Differentiation of Human Adipose-Derived Stem Cells

Background/Aims: Long noncoding RNAs (lncRNAs) play important roles in stem cell differentiation. However, their role in osteogenesis of human adipose-derived stem cells (ASCs), a promising cell source for bone regeneration, remains unknown. Here, we investigated the expression profile and potential roles of lncRNAs in osteogenic differentiation of human ASCs. Methods: Human ASCs were induced to differentiate into osteoblasts in vitro, and the expression profiles of lncRNAs and mRNAs in undifferentiated and osteogenic differentiated ASCs were obtained by microarray. Bioinformatics analyses including subgroup analysis, gene ontology analysis, pathway analysis and co-expression network analysis were performed. The function of lncRNA H19 was determined by in vitro knockdown and overexpression. Quantitative reverse transcription polymerase chain reaction was utilized to examine the expression of selected genes. Results: We identified 1,460 upregulated and 1,112 downregulated lncRNAs in osteogenic differentiated human ASCs as compared with those of undifferentiated cells (Fold change ≥ 2.0, P < 0.05). Among these, 94 antisense lncRNAs, 85 enhancer-like lncRNAs and 160 lincRNAs were further recognized. We used 12 lncRNAs and 157 mRNAs to comprise a coding-non-coding gene expression network. Additionally, silencing of H19 caused a significantly increase in expression of osteogenesis-related genes, including ALPL and RUNX2, while a decrease was observed after H19 overexpression. Conclusion: This study revealed for the first time the global expression profile of lncRNAs involved in osteogenic differentiation of human ASCs and provided a foundation for future investigations of lncRNA regulation of human ASC osteogenesis.

Downregulation of Nrf2 promotes autophagy-dependent osteoblastic differentiation of adipose-derived mesenchymal stem cells

Adipose derived stem cells (ADSCs) are an important source of stem cells for tissue repair and regeneration; therefore, understanding the mechanisms that regulate stem cell differentiation into a specific lineage is critical. The NF-E2-related factor 2 (Nrf2) pathway and autophagy promote cell survival in response to oxidative stress. However, the roles of Nrf2 and autophagy in bone metabolism under oxidative stress are controversial. Here, we explored the involvement of Nrf2 signaling and autophagy on the differentiation of ADSCs under conditions of oxidative stress. Exposure of ADSCs to H2O2 promoted reactive oxygen species (ROS) accumulation concomitant with the reduction of cell viability, upregulation of Nrf2, the induction of apoptosis and autophagy, and the promotion of osteogenesis. Suppression of autophagic activity at particular stages resulted in the activation of the Nrf2 pathway, whereas osteoblastic differentiation of ADSCs was inhibited upon ROS stimulation. Silencing of Nrf2 promoted autophagy and osteoblastic differentiation upon ROS stimulation in vitro, and this effect was confirmed in vivo in a mouse model, in which bone formation was enhanced in mice receiving Nrf2-knockdown ADSCs. Taken together, these findings indicate that a negative interaction between the Nrf2 pathway and autophagy may modulate oxidative stress-induced ADSC osteogenesis, and suggest that Nrf2 is a potential target to regulate the differentiation of ADSCs into a specific lineage.

Adipose-derived stem cells undergo spontaneous osteogenic differentiation in vitro when passaged serially or seeded at low density

Adipose-derived stem cells (ADSCs) are a convenient source of cells for regenerating tissue. Widespread application of ADSCs requires that they propagate efficiently and differentiate in vitro. We investigated the differentiation potential of ADSCs during long-term expansion in vitro and when the cells were seeded at low density. ADSCs were isolated from the inguinal fat pads of 3-week-old male rats, then cultured serially for 12 passages; some ADSCs at passage 3 were seeded at low density. The differentiation potential of ADSCs from passage 3 to passage 12 was assessed by their capacity for adipogenesis and osteogenesis while cultured in specific induction media. Spontaneous osteogenesis of ADSCs at passage 12 and of ADSCs that were seeded at low density was detected by western blotting, alizarin red S staining and measurement of alkaline phosphatase (ALP) activity. We found that with increasing passage number, the adipogenic potential of ADSCs decreased and osteogenic differentiation increased. Alizarin red S staining, bone morphogenetic protein-2 (BMP-2) and runt-related transcription factor 2 (Runx2) expressions, and ALP activity demonstrated that both ADSCs at passage 12 and those that were seeded at low density differentiated into osteoblasts without additional induction factors.

Enhanced Osteogenesis of Adipose-Derived Stem Cells by Regulating Bone Morphogenetic Protein Signaling Antagonists and Agonists.

Although adipose-derived stem cells (ASCs) are an attractive cell source for bone tissue engineering, direct use of ASCs alone has had limited success in the treatment of large bone defects. Although bone morphogenetic proteins (BMPs) are believed to be the most potent osteoinductive factors to promote osteogenic differentiation of ASCs, their clinical applications require supraphysiological dosage, leading to high medical burden and adverse side effects. In the present study, we demonstrated an alternative approach that can effectively complement the BMP activity to maximize the osteogenesis of ASCs without exogenous application of BMPs by regulating levels of antagonists and agonists to BMP signaling. Treatment of ASCs with the amiloride derivative phenamil, a positive regulator of BMP signaling, combined with gene manipulation to suppress the BMP antagonist noggin, significantly enhanced osteogenic differentiation of ASCs through increased BMP-Smad signaling in vitro. Furthermore, the combination approach of noggin suppression and phenamil stimulation enhanced the BMP signaling and bone repair in a mouse calvarial defect model by adding noggin knockdown ASCs to apatite-coated poly(lactic-coglycolic acid) scaffolds loaded with phenamil. These results suggest novel complementary osteoinductive strategies that could maximize activity of the BMP pathway in ASC bone repair while reducing potential adverse effects of current BMP-based therapeutics. Although stem cell-based tissue engineering strategy offers a promising alternative to repair damaged bone, direct use of stem cells alone is not adequate for challenging healing environments such as in large bone defects. This study demonstrates a novel strategy to maximize bone formation pathways in osteogenic differentiation of mesenchymal stem cells and functional bone formation by combining gene manipulation with a small molecule activator toward osteogenesis. The findings indicate promising stem cell-based therapy for treating bone defects that can effectively complement or replace current osteoinductive therapeutics.

Photo-immobilization of bone morphogenic protein 2 on PLGA/HA nanocomposites to enhance the osteogenesis of adipose-derived stem cells

Poly(lactide-co-glycolide) and nano-hydroxyapatite composites are surface-modified with BMP-2 via photo-reactive gelatin to make the composites exhibit excellent bioactivities for the adhesion, proliferation and osteogenic differentiation of ADSCs.

The role of miR-135-modified adipose-derived mesenchymal stem cells in bone regeneration

Tissue-engineering technology employing genetically-modified mesenchymal stem cells combined with proper scaffolds represents a promising strategy for bone regeneration. Elucidating the underlying mechanisms that govern the osteogenesis of mesenchymal stem cells will give deeper insights into the regulatory patterns, as well as provide more effective methods to enhance bone regeneration. In this study, miR-135 was identified as an osteogenesis-related microRNA that was up-regulated during the osteogenesis of rat adipose-derived stem cells (ADSCs). Gain- and loss-of-function experiments using a lentiviral expression system showed that Homeobox A2 (Hoxa2) was negatively regulated by miR-135, and luciferase reporter assay further indicated that miR-135 repressed Hoxa2 expression through binding to the 3′-untranslated region (3′-UTR) of the Hoxa2 mRNA. In vitro analyses showed that the overexpression of miR-135 significantly enhanced the expression of bone markers and extracellular matrix calcium deposition, whereas the knockdown of miR-135 suppressed these processes. Transduced ADSCs were then combined with poly(sebacoyl diglyceride) (PSeD) scaffold to repair a critical-sized calvarial defects in rats. The results showed that the overexpression of miR-135 significantly promoted new bone formation with higher bone mineral density (BMD) and number of trabeculae (Tb.N), as well as larger areas of newly formed bone and mineralization labeled by tetracycline, calcein and alizarin red. In contrast, the knockdown of miR-135 attenuated these processes. Additionally, immunohistochemical analyses showed that transduced ADSCs participated in new bone formation and a miR-135/Hoxa2/Runx2 pathway might contribute to the regulation of ADSC osteogenesis and bone regeneration. Taken together, our data suggested that miR-135 positively regulated the osteogenesis and bone regeneration of ADSCs both in vitro and in vivo. Thus, the combination of miR-135-modified ADSCs and the PSeD scaffold may serve as a promising and effective method to repair critical-sized bone defects.

A Combination of Low-Intensity Pulsed Ultrasound and Nanohydroxyapatite Concordantly Enhances Osteogenesis of Adipose-Derived Stem Cells From Buccal Fat Pad.

The osteogenic induction of adipose-derived stem cells (ADSCs) has been regarded as an important step in bone tissue engineering. In the present study, we focused on the buccal fat pad (BFP) as a source of adipose tissue, since BFPs are encapsulated by adipose tissue and are often coextirpated during oral surgery. Low-intensity pulsed ultrasound (LIPUS) is effective in the treatment of fractures, and nanohydroxyapatite (NHA) is known as a bone substitute material. Here we investigated the synergistic effects of LIPUS and NHA in the osteogenesis of ADSCs. A combination of LIPUS irritation and NHA as a scaffold significantly increased the osteogenic differentiation of ADSCs in vitro, and in our in vivo study in which ADSCs were transplanted into calvarial bone defects of nude mice, the combinational effect greatly enhanced the new bone formation of the margin of the defects. These results demonstrate that synergistic effects of LIPUS and NHA are capable of effectively inducing the differentiation of ADSCs into osteoblasts, and they suggest a novel therapeutic strategy for bone regeneration by the autotransplantation of ADSCs.

Adipose-derived stem cells and BMP-2 delivery in chitosan-based 3D constructs to enhance bone regeneration in a rat mandibular defect model.

Reconstructing segmental mandiblular defects remains a challenge in the clinic. Tissue engineering strategies provide an alternative option to resolve this problem. The objective of the present study was to determine the effects of adipose-derived stem cells (ASCs) and bone morphogenetic proteins-2 (BMP-2) in three-dimensional (3D) scaffolds on mandibular repair in a small animal model. Noggin expression levels in ASCs were downregulated by a lentiviral short hairpin RNA strategy to enhance ASC osteogenesis (ASCs(Nog-)). Chitosan (CH) and chondroitin sulfate (CS), natural polysaccharides, were fabricated into 3D porous scaffolds, which were further modified with apatite coatings for enhanced cellular responses and efficient delivery of BMP-2. The efficacy of 3D apatite-coated CH/CS scaffolds supplemented with ASCs(Nog-) and BMP-2 were evaluated in a rat critical-sized mandibular defect model. After 8 weeks postimplantation, the scaffolds treated with ASCs(Nog-) and BMP-2 significantly promoted rat mandibular regeneration as demonstrated by micro-computerized tomography, histology, and immunohistochemistry, compared with the groups treated with ASCs(Nog-) or BMP-2 alone. These results suggest that our combinatorial strategy of ASCs(Nog-)+BMP-2 in 3D apatite microenvironments can significantly promote mandibular regeneration, and these may provide a potential tissue engineering approach to repair large bony defects.

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

Bone tissue engineering (BTE) is now a promising research 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 renewal and multi-lineage differentiation. Unlike embryonic 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 earliest-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 application. Afterwards, a new stem cell source coming from adipose tissue, so-called adipose-derived stem cells (ASCs), is found to be more suitable in clinical application because of high stem cells yield from lipoaspirates, faster cell proliferation and less discomfort and morbidities during harvesting procedure. However, the osteogenic capacity of ASCs is now still debated because 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 potential. 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.

BMP-2 promotes chondrogenesis of rat adipose-derived stem cells by using a lentiviral system.

Osteoporosis poses a major public health threat in aging societies. Adipose-derived stem cells (ADSCs) are multipotent adult stem cells that have the ability to yield mesenchymal stem cells, and have the potential to undergo osteogenesis and bone regeneration. Bone morphogenetic proteins (BMPs) have been demonstrated to upregulate bone gene expression after mechanical injury and to improve bone injury repair. This study aimed to produce BMP-2 expression in ADSCs by using lentiviral vectors. Subcutaneous adipose tissue from 4-week-old male Sprague-Dawley rats was used. Oil red O staining was used to detect adipocyte formation from ADSCs. Induction of ADSC osteogenesis was confirmed with Alizarin red S staining. The recombinant lenti-hBMP-2/neo was constructed to infect ADSCs, BMP-2 expression was measured by immunoblotting analysis, and cellular alkaline phosphatase levels were examined. We found that >70% of ADSC cells could be induced to differentiate into osteocytes or adipocytes. Under osteogenic induction, ADSCs showed increased intracellular calcium deposition, the formation of calcium tubercles, and the disappearance of cellular structures in calcium tubercles. After infection of ADSCs by lenti-hBMP-2/neo, BMP-2 was expressed after doxycycline induction. We, thus, conclude that ADSCs maintain vigorous growth ex vivo and possess stem cell-like properties. When infected with lenti-hBMP-2/neo, ADSCs can be induced to promote BMP-2 expression.

Osteogenesis of adipose-derived stem cells on polycaprolactone-β-tricalcium phosphate scaffold fabricated via selective laser sintering and surface coating with collagen type I

The current study aimed to fabricate three-dimensional (3D) polycaprolactone (PCL), polycaprolactone and β-tricalcium phosphate (PCL-TCP) scaffolds via a selective laser-sintering technique (SLS). Collagen type I was further coated onto PCL-TCP scaffolds to form PCL-TCP-COL scaffolds. The physical characters of these three scaffolds were analysed. The osteogenic potential of porcine adipose-derived stem cells (pASCs) was compared among these three scaffolds in order to find an optimal scaffold for bone tissue engineering. The experimental results showed no significant differences in pore size and porosity among the three scaffolds; the porosity was ca. 75-77% and the pore size was ca. 300-500 µm in all three. The compressive modulus was increased from 6.77 ± 0.19 to 13.66 ± 0.19 MPa by adding 30% β-TCP into a 70% PCL scaffold. No significant increase of mechanical strength was found by surface-coating with collagen type I. Hydrophilicity and swelling ratios showed statistical elevation (p < 0.05) after collagen type I was coated onto the PCL-TCP scaffolds. The in vitro study demonstrated that pASCs had the best osteogenic differentiation on PCL-TCP-COL group scaffolds, due to the highest ALP activity, osteocalcin mRNA expression and mineralization. A nude mice experiment showed better woven bone and vascular tissue formation in the PCL-TCP-COL group than in the PCL group. In conclusion, the study demonstrated the ability to fabricate 3D, porous PCL-TCP composite scaffolds (PCL:TCP = 70:30 by weight) via an in-house-built SLS technique. In addition, the osteogenic ability of pASCs was found to be enhanced by coating COL onto the PCL-TCP scaffolds, both in vitro and in vivo. Copyright © 2013 John Wiley & Sons, Ltd.

The Roles of Bone Morphogenetic Proteins and Their Signaling in the Osteogenesis of Adipose-Derived Stem Cells

Large-size bone defects can severely compromise both aesthetics and musculoskeletal functions. Adipose-derived stem cells (ASCs)-based bone tissue engineering has recently become a promising treatment strategy for the above situation. As robust osteoinductive cytokines, bone morphogenetic proteins (BMPs) are commonly used to promote the osteogenesis of ASCs. In this process, BMP signaling plays a pivotal role. However, it remains ambiguous how the pleiotrophic BMPs are involved in the commitment of ASCs along osteogenesis instead of other lineages, such as adipogenesis. BMP receptor type-IB, extracellular signal-regulated kinase, and Wnt5a appear to be the main switches controlling the in vitro osteogenic commitment of ASCs. Tumor necrosis factor-alpha, an acute inflammatory cytokine, is reported to play an important role in mediating osteogenic commitment of ASCs in vivo. In addition, various active agents and methods have been used to enhance and accelerate the osteogenesis of ASCs through promoting BMP signaling. In this review, we summarize the current knowledge on the roles of BMPs and their signaling in the osteogenesis of ASCs in vitro and in vivo.