Human Bone Mesenchymal Stromal Cells Research Articles

Retraction Note: miR-381 modulates human bone mesenchymal stromal cells (BMSCs) osteogenesis via suppressing Wnt signaling pathway during atrophic nonunion development

Retraction Note: miR-381 modulates human bone mesenchymal stromal cells (BMSCs) osteogenesis via suppressing Wnt signaling pathway during atrophic nonunion development

Exosomes derived from mesenchymal stromal cells exert a therapeutic effect on hypoxia-induced pulmonary hypertension by modulating the YAP1/SPP1 signaling pathway

ObjectiveHypoxic pulmonary hypertension (HPH) is a progressive and life-threatening disease characterized by perivascular inflammation, pulmonary vascular remodeling, and occlusion. Mesenchymal stromal cell-derived exosomes (MSC-exo) have emerged as potential therapeutic agents due to their role in cell communication and the transportation of bioactive molecules. In this study, we aimed to investigate the therapeutic effects of MSC-exo against HPH and elucidate the underlying molecular mechanism. MethodsExosomes were isolated from conditioned media of human bone mesenchymal stromal cells using ultracentrifugation and characterized through western blotting, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). An HPH animal model was established in male SD rats, and MSC-exo or phosphate-buffered saline (PBS) were administered via the tail vein for three weeks. Subsequently, right ventricular systolic pressure (RVSP), right ventricular hypertrophy index (RVHI), and pulmonary vascular remodeling were evaluated. Lung tissues from HPH rats and normal rats underwent high-throughput sequencing and transcriptomic analysis. Gene Ontology (GO) analysis was employed to identify upregulated differentially expressed genes. Additionally, rat pulmonary artery smooth muscle cells (PASMC) exposed to platelet-derived growth factor-BB (PDGF-BB) were used to simulate HPH-related pathological behavior. In vitro cellular models were established to examine the molecular mechanism of MSC-exo in HPH. ResultsMSC-exo administration protected rats from hypoxia-induced increases in RVSP, RVHI, and pulmonary vascular remodeling. Additionally, MSC-exo alleviated PDGF-BB-induced proliferation and migration of PASMC. Transcriptomic analysis revealed 267 upregulated genes in lung tissues of HPH rats compared to control rats. Gene Ontology analysis indicated significant differences in pathways associated with Yes Associated Protein 1 (YAP1), a key regulator of cell proliferation and organ size. RT-qPCR and western blot analysis confirmed significantly increased expression of YAP1 in HPH lung tissues and PASMC, which was inhibited by MSC-exo treatment. Furthermore, analysis of datasets demonstrated that Secreted Phosphoprotein 1 (SPP1), also known as Osteopontin (OPN), is a downstream binding protein of YAP1 and can be upregulated by PDGF-BB. MSC-exo treatment reduced the expression of both YAP1 and SPP1. Lentivirus-mediated knockdown of YAP1 inhibited PDGF-BB-induced PASMC proliferation, migration, and SPP1 protein levels. ConclusionOur findings demonstrate that MSC-exo exert a therapeutic effect against hypoxia-induced pulmonary hypertension by modulating the YAP1/SPP1 signaling pathway. The inhibition of YAP1 and downstream SPP1 expression by MSC-exo may contribute to the attenuation of pulmonary vascular remodeling and PASMC proliferation and migration. These results suggest that MSC-exo could serve as a potential therapeutic strategy for the treatment of HPH. Further investigations are warranted to explore the clinical applicability of MSC-exo-based therapies in HPH patients.

MiR-100-5p inhibits osteogenic differentiation of human bone mesenchymal stromal cells by targeting TMEM135.

Osteoporosis is a disorder characterized by reduced bone mass, disruption of bone microarchitecture, and a propensity to fracture. The osteogenic differentiation of human bone mesenchymal stromal cells (hBMSCs) exerts a critical effect on preventing bone loss during osteoporosis. Herein, the study recognized miR-100-5p as a deregulated miRNA during osteoporosis (upregulated) and BMSC osteogenic differentiation (downregulated). miR-100-5p was upregulated in osteoporosis patients-isolated BMSCs compared to non-osteoporosis trauma patients-isolated BMSCs. hBMSCs, overexpression inhibited hBMSC proliferation and osteogenic differentiation, whereas miR-100-5p inhibition exerted opposite effects. TMEM135 was downregulated in osteoporosis and upregulated in differentiated osteoblasts, as well as downregulated upon the overexpression of miR-100-5p. MiR-100-5p directly targeted and inhibited TMEM135. In hBMSCs, TMEM135 silencing also inhibited hBMSC osteogenic differentiation. When co-transfected to hBMSCs, antagomir-100-5p promoted, whereas TMEM135 silencing inhibited hBMSC osteogenic differentiation; TMEM135 knockdown dramatically attenuated the effects of miR-100-5p inhibition. Taken together, miR-100-5p forms a regulatory axis with TMEM135 by direct binding. The miR-100-5p/TMEM135 axis modulates hBMSC differentiation into osteoblast. Considering the critical effect of BMSC osteogenesis on osteoporosis, this axis might play a role in osteoporosis, and further in vivo and clinical investigations are required.

Cytostatic Effects of Polyethyleneimine Surfaces on the Mesenchymal Stromal Cell Cycle.

Polyelectrolytes assembled layer-by-layer (PEMs) are commonly used as functional coatings to build-up biological interfaces, particularly suitable as compatible layers for the interaction with a biological medium, providing suitable conditions to promote or prevent cell seeding while maintaining the phenotype. The proper assessment of the biocompatibility of PEMs and the elucidation of the related mechanisms are therefore of paramount importance. In this study, we report in detail the effect of two different PEM endings, polystyrene sulfonate (PSS) and polyethylenimine (PEI), respectively, on the cell adhesion, growth, and viability of human bone mesenchymal stromal cells (MSCs). The results have shown that PSS-ended substrates appear to be the most suitable to drive the cell adhesion and phenotype maintenance of MSCs, showing good biocompatibility. On the contrary, while the cells seem to adhere more quickly and strongly on the PEI-ended surfaces, the interaction with PEI significantly affects the growth and viability, reducing the cell spreading capability, by sequestering the adhesion molecules already in the very early steps of cell–substrate contact. These results point to the promotion of a cytostatic effect of PEI, rather than the often-claimed cytotoxicity.

A heterogeneous TiO2/SrTiO3 coating on titanium alloy with excellent photocatalytic antibacterial, osteogenesis and tribocorrosion properties

In order to meet the clinical demand for titanium implants, the heterogeneous structure of TiO2/SrTiO3 coating was in situ fabricated on the surface of Ti6Al4V alloy by a facile way. The well-designed Ti6Al4V/TiO2/SrTiO3 composite exhibits a strong photocatalytic antibacterial efficiency against Escherichia coli (E. coli). The suitable energy band structure, improved light absorption and enhanced carrier separation of TiO2/SrTiO3 heterojunction facilitate the generation of bactericidal reactive oxygen species (ROS) under the illumination of UV light. The biocompatible SrTiO3 component effectively favors the adhesion, proliferation and osteogenic differentiation of human bone mesenchymal stromal cells (hBMSCs) in vitro. It is worth noting that the dense oxide coating provides a reliable barrier against tribocorrosion for the titanium alloy substrate, and the wear volume loss of the Ti6Al4V/TiO2/SrTiO3 reduces to 1/8 of that of the bare Ti6Al4V alloy in simulated body fluid. In this work, a multifunctional coating system was proposed to provide inspiration for the development of novel artificial bone implant materials.

Bioengineered Fluorescent Nanoprobe Conjugates for Tracking Human Bone Cells: In Vitro Biocompatibility Analysis.

Herein, we validated novel functionalized hybrid semiconductor bioconjugates made of fluorescent quantum dots (QD) with the surface capped by chitosan (polysaccharide) and chemically modified with O-phospho-L-serine (OPS) that are biocompatible with different human cell sources. The conjugation with a directing signaling molecule (OPS) allows preferential accumulation in human bone mesenchymal stromal cells (HBMSC). The chitosan (Chi) shell with the fluorescent CdS core was characterized by spectroscopical (UV spectrophotometry and photoluminescence), by morphological techniques (Transmission Electron Microscopy (TEM)) and showed small size (ø 2.3 nm) and a stable photoluminescence emission band. The in vitro biocompatibility results were not dependent on the polysaccharide chain length (Chi with higher and lower molecular weight) but were remarkably affected by the surface modification (Chi or Chi-OPS). In addition, the efficiency of nanoparticles uptake by the cells was dependent on cells nature (human primary cells or cell lines) and tissue source (bone or skin) in the presence or absence of the OPS modification. The complex cellular uptake pathways involved in the cell labeling with the nanoparticles do not interfere on the normal cellular biology (adhesion and proliferation), osteogenic differentiation, and gene expression. The bone cells particles uptake evaluation showed a possible pathway by Caveolin-1 that regulates cell transduction in the membrane’s Caveolae. Caveolae mediates non-specific endocytosis, and it is upregulated in HBMSC. The OPS-modified nanoparticles promoted an intense intracellular trafficking by the HBMSCs that showed late-osteoblast phenotype with an increase of extracellular matrix (ECM) mineralization (Alizarin red and Von Kossa staining for calcium phosphate crystals). In this work, the OPS modified bioconjugated QD proved to be a reliable and stable fluorescent bioprobe for cell imaging and targeting research that could also help in clarifying some cellular mechanisms of particles intracellular traffic through the cytoplasmic membrane and osteogenic differentiation induction. The in vitro HBMSC’s biocompatibility responses indicated that the OPS-modified chitosan QDs have a prospective future in laboratory and pre-clinical applications such as bioimaging analysis and for ex-vivo cellular evaluation of biomedical implants.

High-Frequency Repetitive Transcranial Magnetic Stimulation Mediates Autophagy Flux in Human Bone Mesenchymal Stromal Cells via NMDA Receptor-Ca2+-Extracellular Signal-Regulated Kinase-Mammalian Target of Rapamycin Signaling.

AimRepetitive transcranial magnetic stimulation (rTMS) is a non-invasive and safe technique for treatment of central and peripheral nerve injury. In recent years, this technique has been widely used in clinic, and an increasing number of studies have reported its mechanisms. In this study, we investigated the mechanisms of rTMS-mediated autophagy flux in human bone mesenchymal stromal cells (BMSCs).MethodsA frequency of 50 Hz was employed. Cells were divided into five groups: (1) normal, (2) sham, (3) 0.5 T, (4) 1.0 T, and (5) 1.5 T. Cells were stimulated for 20 min/day. The levels of p62, LC3-II/I, phosphorylated extracellular signal-regulated kinase (p-ERK), ERK, phosphorylated-AKT (p-AKT), AKT, phosphorylated mammalian target of rapamycin (p-mTOR), mTOR, phosphorylated protein kinase A (p-PKA), PKA, phosphorylated epidermal growth factor receptor (p-EGFR), EGFR, Nanog, Oct4, Sox2, and NMDA receptor (NMDAR1) were investigated by western blotting. Intracellular calcium (Ca2+) levels were quantified by flow cytometry. p62 and LC3 expression was also assessed by immunofluorescence analysis.ResultsIn the 0.5 T group, rTMS increased the expression of LC3-II/I, p-ERK/ERK, and NMDAR1 and decreased the levels of p62 and p-mTOR/mTOR than in the normal group. The ratio of p-AKT/AKT, p-PKA/PKA, and p-EGFR/EGFR and the expression of Nanog, Oct4, and Sox2 remained unchanged. Immunofluorescence analysis revealed colocalization of p62 with LC3 puncta, and flow cytometry analysis displayed that Ca2+ levels were elevated. However, in the 1.0 and 1.5 T groups, no changes in the expression of these autophagy markers were observed.ConclusionIn the 0.5 T group, high-frequency rTMS can induce autophagy through NMDAR–Ca2+–ERK–mTOR signaling in BMSCs. In the 1.0 and 1.5 T groups, autophagy is not activated.

High Glucose Level Impairs Human Mature Bone Marrow Adipocyte Function Through Increased ROS Production.

Bone marrow adipocytes (BMAds) accumulate in aging, menopause, and metabolic diseases such as Type 2 diabetes. These osteoporotic conditions are associated with oxidative stress and hyperglycemia which are both considered as critical factors underlying bone fragility. Glucose excess and reactive oxygen species (ROS) are known to favor adipogenesis over osteoblastogenesis. In this study, we investigated whether high glucose exposure could determine dysfunction of mature BMAds, specifically through ROS production. The effects of low (LG, 5 mM) or high glucose (HG, 25 mM) concentrations were examined using human bone mesenchymal stromal cells (hBMSCs) in the time course of differentiation, and, up to 21 days once adipocytes were mature. HG did not alter the adipocyte differentiation process of hBMSCs. Yet, after 21 days under HG exposure, PPARG, CEBPA, and adiponectin mRNA expressions were decreased. These alterations were also observed following adipogenic inducer withdrawal as well as in adipocytes fully differentiated in LG then cultured in HG for the last 11 days. Without inducers, HG condition also led to decreased leptin mRNA level. Importantly, intracellular and extracellular ROS concentrations measured using Amplex Red were significantly raised by 50% under HG exposure. This rise was observed once adipocytes ended differentiation and was reproduced within the different cell culture settings without any cytotoxicity. Among genes involved in ROS metabolism, the mRNA level of the H2O2 generating enzyme NOX4 was found upregulated in the presence of HG. Following cell separation, mature BMAds were shown to overproduce ROS and to display the gene alterations in contrast to non-lipid-laden cells. Finally, a non-lethal treatment with a pro-oxidant agent under LG condition reduces the mRNA levels of PPARG, adiponectin, and leptin as the HG condition does in the absence of inducers, and amplifies the effect of glucose excess on gene expression. HG concentration drives mature BMAds toward altered expression of the main adipokines and transcriptional factors. These perturbations are associated with a rise in ROS generation likely mediated through enhanced expression of NOX4. Mature BMAds are thus responsive to changes in glucose and ROS concentrations, which is relevant regarding with their phenotype and function in age- or metabolic disease-related osteoporosis.

CircRNA_0016624 could sponge miR-98 to regulate BMP2 expression in postmenopausal osteoporosis

BackgroundCircular RNAs (circRNAs) are emerging as important regulators in human disease. The expression profile and mechanism of circRNAs in postmenopausal osteoporosis remains largely unknown. Bone morphogenetic protein 2 (BMP2) is known to play important role in inducing osteogenic differentiation. MiR-98 was reported to regulate osteogenic differentiation of human bone mesenchymal stromal cells by targeting BMP2. AimWe aimed to analyze circRNA expression profiles in osteoporosis and explore the molecular mechanism of circRNA_0016624 and interaction between circRNA_0016624, miR-98 and BMP2 during osteogenic differentiation. MethodsRNA-seq and bioinformatics analysis was performed in postmenopausal osteoporosis patients to screen for differentially expressed circRNAs. MiRanda and TargetScan were used to detect miR-98 binding sites of circRNA_0016624 and the target relationship was confirmed by dual luciferase assay. Expression level of circRNA_0016624, miR-98 and BMP2 were measured by qRT-PCR or Western blot. ARS staining was used to observe the level of osteogenic differentiation after transfection. ResultsThere were 387 circRNAs were differentially expressed in osteoporosis (|fold change| > 2 and P-value < 0.01). circRNA_0016624 and BMP2 were down-regulated in osteoporosis. CircRNA_0016624 could sponge miR-98 and regulate miR-98 expression. Overexpression of circRNA_0016624 promoted the expression of BMP2 and prevented osteoporosis.Conclusion: circRNA_0016624 could sponge miR-98 and enhance BMP2 expression, thus circRNA_0016624 prevents osteoporosis and may provide a novel therapeutic strategy.

MiR-381 modulates human bone mesenchymal stromal cells (BMSCs) osteogenesis via suppressing Wnt signaling pathway during atrophic nonunion development

The osteogenic differentiation of human bone mesenchymal stromal cells (BMSCs) has been considered as a central issue in fracture healing. Wnt signaling could promote BMSC osteogenic differentiation through inhibiting PPARγ. During atrophic nonunion, Wnt signaling-related factors, WNT5A and FZD3 proteins, were significantly reduced, along with downregulation of Runx2, ALP, and Collagen I and upregulation of PPARγ. Here, we performed a microarray analysis to identify differentially expressed miRNAs in atrophic nonunion tissues that were associated with Wnt signaling through targeting related factors. Of upregulated miRNAs, miR-381 overexpression could significantly inhibit the osteogenic differentiation in primary human BMSCs while increase in PPARγ protein level. Through binding to the 3′UTR of WNT5A and FZD3, miR-381 modulated the osteogenic differentiation via regulating β-catenin nucleus translocation. Moreover, PPARγ, an essential transcription factor inhibiting osteogenic differentiation, could bind to the promoter region of miR-381 to activate its expression. Taken together, PPARγ-induced miR-381 upregulation inhibits the osteogenic differentiation in human BMSCs through miR-381 downstream targets, WNT5A and FZD3, and β-catenin nucleus translocation in Wnt signaling. The in vivo study also proved that inhibition of miR-381 promoted the fracture healing. Our finding may provide a novel direction for atrophic nonunion treatment.

Remodeling of Glycosaminoglycans During Differentiation of Adult Human Bone Mesenchymal Stromal Cells Toward Hepatocytes.

There is a critical need to generate functional hepatocytes to aid in liver repair and regeneration upon availability of a renewable, and potentially personalized, source of human hepatocytes (hHEP). Currently, the vast majority of primary hHEP are obtained from human tissue through cadavers. Recent advances in stem cell differentiation have opened up the possibility to obtain fully functional hepatocytes from embryonic or induced pluripotent stem cells, or adult stem cells. With respect to the latter, human bone marrow mesenchymal stromal cells (hBMSCs) can serve as a source of autogenetic and allogenic multipotent stem cells for liver repair and regeneration. A major aspect of hBMSC differentiation is the extracellular matrix (ECM) composition and, in particular, the role of glycosaminoglycans (GAGs) in the differentiation process. In this study, we examine the influence of four distinct culture conditions/protocols (T1-T4) on GAG composition and hepatic markers. α-Fetoprotein and hepatocyte nuclear factor-4α were expressed continually over 21 days of differentiation, as indicated by real time quantitative PCR analysis, while albumin (ALB) expression did not begin until day 21. Hepatocyte growth factor (HGF) appears to be more effective than activin A in promoting hepatic-like cells through the mesenchymal-epithelial transition, perhaps due to the former binding to the HGF receptor to form a unique complex that diversifies the biological functions of HGF. Of the four protocols tested, uniform hepatocyte-like morphological changes, ALB secretion, and glycogen storage were found to be highest with protocol T2, which involves both early- and late-stage combinations of growth factors. The total GAG profile of the hBMSC ECM is rich in heparan sulfate (HS) and hyaluronan, both of which fluctuate during differentiation. The GAG profile of primary hHEP showed an HS-rich ECM, and thus, it may be possible to guide hBMSC differentiation to more mature hepatocytes by controlling the GAG profile expressed by differentiating cells.

MiR-148a promotes myocardial differentiation of human bone mesenchymal stromal cells via DNA methyltransferase 1 (DNMT1).

MicroRNAs have potential to modulate the differentiation of stem cells. In previous study, we found that miR-148a was up-regulated in myocardial differentiation of human bone mesenchymal stromal cells (hBMSCs) induced by 5'-azacytidine. However, the role of miR-148a in regulating this process still remains unclear. In this study, we investigated the function and molecular mechanism of miR-148a in myocardial differentiation of hBMSCs. We found that miR-148a was significantly increased while DNA methyltransferase 1 (DNMT1) was significantly decreased in myocardial differentiation of hBMSCs. Then, the dual luciferase reporter assays method indicated that DNMT1 was the direct target of miR-148a. In addition, we showed that up-regulation of miR-148a could enhance myocardial differentiation of hBMSCs, while down-regulation of miR-148a could inhibit myocardial differentiation process. Moreover, knockdown of DNMT1 could block the role of miR-148a in promoting myocardial differentiation of hBMSCs. Finally, MiR-148a acted on methylation level of GATA-4 and knockdown of DNMT1 could block this function. Therefore, our results indicate that miR-148a plays a vital role in regulating myocardial differentiation of hBMSCs by targeting DNMT1.

MicroRNA-98 regulates osteogenic differentiation of human bone mesenchymal stromal cells by targeting BMP2.

To study the effects of microRNA‐98 (miR‐98) on human bone mesenchymal stromal cells (hBMSCs). The patients undergoing hip arthroplasty were selected by inclusion/exclusion criteria for this study. The extracted hBMSCs were detected of osteogenic differentiation by alizarin red S staining, and of cell phenotype by flow cytometry. Bioinformatics, dual luciferase report, western blotting, RT‐PCR and immunoblotting were used in our study. The hBMSCs were divided into miR‐98 mimics, miR‐98 negative control (NC), miR‐98 inhibitors, Mock and miR‐98 inhibitors + siBMP2 groups. Human bone mesenchymal stromal cells were extracted and purified in vitro and had specific cytological morphology, surface markers and abilities of self‐renewal and differentiation. Compared with the NC group and Mock group, the miR‐98 mimics group showed increased miR‐98 level while the miR‐98 inhibitors group decreased miR‐98 level (both P < 0.01). Dual luciferase reporter showed BMP2 was the target gene of miR‐98. The levels of mRNA and protein expression of BMP2, protein expression of RUNX2, alkaline phosphatase activity and osteocalcin content significantly decreased in the miR‐98 mimics group while increased in the miR‐98 inhibitors group and showed no changes in the NC group and Mock group (all P < 0.05). The miR‐98 mimics group showed obviously declined stained red particles and the miR‐98 inhibitors group showed opposite result. After lowering the expression of miR‐98, osteogenic differentiation ability of hBMSCs rose, which was weakened by the transfection with siBMP2. miR‐98 may regulate osteogenic differentiation of hBMSCs by targeting BMP2.

Episomal plasmid-based generation of induced pluripotent stem cells from fetal femur-derived human mesenchymal stromal cells

Human bone mesenchymal stromal cells derived from fetal femur 55days post-conception were reprogrammed to induced pluripotent stem cells using episomal plasmid-based expression of OCT4, SOX2, NANOG, LIN28, SV40LT, KLF4 and c-MYC and supplemented with the following pathway inhibitors — TGFβ receptor inhibitor (A-83-01), MEK inhibitor (PD325901), GSK3β inhibitor (CHIR99021) and ROCK inhibitor (HA-100). Successful induction of pluripotency in two iPS-cell lines was demonstrated in vitro and by the Pluritest.

Evaluation of early stage human bone marrow stromal proliferation, cell migration and osteogenic differentiation on μ-MIM structured stainless steel surfaces

It is well established that surface topography greatly affect cell-surface interactions. In a recent study we showed that microstructured stainless steel surfaces characterized by the presence of defined hexagonally arranged hemisphere-like structures significantly affected cell architecture (shape and focal adhesion size) of primary human bone mesenchymal stromal cells. This study aimed at further investigating the influence these microstructures (microcline protruding hemispheres) on critical aspects of cell behaviour namely; proliferation, migration and osteogenic differentiation. As with previously reported data, we used primary human bone mesenchymal stromal cells to investigate such effects at an early stage in vitro. Cells of different patients were utilised for cell migration studies. Our data showed that an increase in cell proliferation was exhibited as a function of surface topography (hemispheres). Cell migration velocity also varied as a function of surface topography on patient specific basis and seems to relate to the differentiated state of the seeded cell population (as demonstrated by bALP positivity). Osteogenic differentiation, however, did not exhibit significant variations (both up and down-regulation) as a function of both surface topography and time in culture.

Influence of perfusion and compression on the proliferation and differentiation of bone mesenchymal stromal cells seeded on polyurethane scaffolds

In the present study, a porous meniscal-shaped scaffold consisting of polyurethane (PU)-based 1, 4-butanediisocyanate (BDI), which provided a 3-D culture condition for human bone mesenchymal stromal cells (hBMSC) was employed. A bioreactor was utilized to produce perfusion and mechanical stimulations. The viability, proliferation and fibro-cartilaginous differentiation of the hBMSC cultured on the PU-based meniscal scaffold were investigated during the perfusion and mechanical stimulation process. In addition, the mechanical properties of the cell-laden scaffolds were examined as well. Our finding indicated that the perfusion (10 ml/min) and on-off cyclic compressions mechanical stimulation (10% strain, 0.5 Hz, 4 times/day, 2 h/time with 4 h of rest thereafter) maintained the viability and promoted the proliferation of hBMSC over 2 weeks. The on-off cyclic compression caused a 1.85 fold increase in equilibrium modulus. Meanwhile, type I procollagen produced by hBMSC was increased for 3.02-fold after 2 weeks culture. On the other hand, the irrigating medium enhanced the synthesis of type III procollagen for 2.24-fold after 2 weeks. Tensile modulus was elevated for 2.02-fold in perfusion group after 1 week, which was decreased after 2 weeks unexpectedly. Our study suggests that the perfusion and on-off compression are promising to enhance the functional properties of the hBMSC-laden PU-based meniscal scaffold.

The osteogenic properties of CaP/silk composite scaffolds

The rationale for the present study was to develop porous CaP/silk composite scaffolds with a CaP-phase distribution and pore architecture better suited to facilitate osteogenic properties of human bone mesenchymal stromal cells (BMSCs) and in vivo bone formation abilities. This was achieved by first preparing CaP/silk hybrid powders which were then incorporated into silk to obtain uniform CaP/silk composite scaffolds, by means of a freeze-drying method. The composition, microstructure and mechanical properties of the CaP/silk composite scaffolds were ascertained by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscope (SEM) and a universal mechanical testing machine. BMSCs were cultured in these scaffolds and cell proliferation analyzed by confocal microscopy and MTS assay. Alkaline phosphatase (ALP) activity and osteogenic gene expression were assayed to determine if osteogenic differentiation had taken place. A calvarial defect model in SCID mice was used to determine the in vivo bone forming ability of the hybrid CaP/silk scaffolds. Our results showed that incorporating the hybrid CaP/silk powders into silk scaffolds improved both pore structure architecture and distribution of CaP powders in the composite scaffolds. By incorporating the CaP phase into silk scaffolds in vitro osteogenic differentiation of BMSCs was enhanced and there was increased in vivo cancellous bone formation. Here we report a method with which to prepare Ca/P composite scaffolds with a pore structure and Ca/P distribution better suited to facilitate BMSC differentiation and bone formation.