Bone-derived Cells Research Articles

Kartogenin, transforming growth factor-β1 and bone morphogenetic protein-7 coordinately enhance lubricin accumulation in bone-derived mesenchymal stem cells.

Osteoarthritis, a common joint degeneration, can cause breakdown of articular cartilage with the presence of lubricin metabolic abnormalities. Lubricin is a multi-level chondroprotective mucinous glycoprotein in articular joints. Joint defect and infection is elevated and accompanied by accelerated cartilage lesions involving degradation and loss of lubricin. However, a novel, heterocyclic compound called kartogenin (KGN) was discovered to stimulate chondrogenic differentiation of bone-derived mesenchymal stem cells (BMSCs). And the synergistic effect of transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-7 (BMP-7) could provoke lubricin accumulation. This paper attempted to explore the connection between accumulation of lubricin and the effect of TGF-β1, BMP-7 and/or KGN. Hence, we investigated the expression and secretion of lubricin in BMSCs treated with different combinations of TGF-β1, BMP-7, and/or KGN. Using an in vitro BMSCs system, we observed the content of lubricin from BMSCs treated with TGF-β1, BMP-7, and KGN was the highest at both the protein level and the gene level. The accumulation of lubricin was enhanced coordinately by the increase of synthesis and decrease of degradation possibly via c-Myc and adamts5 pathway. These results further suggested that supplementation of the defect parts with lubricin by using growth factors and small molecules showed a promising potential on preventing joint deterioration in patients with acquired or genetic deficiency of lubricin in the future of regenerative medicine.

Investigating Cell Surface Markers and Differentiation Potential of Compact Bone-Derived Mesenchymal Stem Cells

Background: The differentiation potential of mesenchymal stem cells (MSCs) derived from the bone-tissue to multiple lineages is not clear. Objective: This study was conducted to investigate the surface antigen expression and multilineage stem cell potential of the cells derived from culture of collagenase digested marrow-free compact bones of C57BL/6 mouse. Materials & Methods: Long bones of C57BL/6 mouse (n=6) were collected aseptically and bone marrow was flushed out. Collagenase-digested bone fragments were washed and cultured in plastic flasks. The plastic-adherent fibroblast-like spindle-shaped cells were cultured sequentially in multiple passages in low-glucose DMEM (Dulbecco's Modified Eagle's Medium) supplemented with 15% FBS (Foetal Bovine Serum) and antibiotics in a 37°C incubator with 5% CO 2 . Immu- nophenotyping for cell surface markers was done using flow cytometry. The cells were differentiated into the osteoblastic, adipogenic and chondrogenic lineages. Results: The culture of the adherent cells exhibited active proliferation and multiplication in consequent passages. The cultured cells revealed evidence of adipogenic and osteogenic differentiation confirmed by staining with oil red O and von Kossa stains. Under flow cytometry observation, a significant proportion of cultured cells expressed CD29 and stem cell antigen (Sca-1). Only 9.8% cells showed expression of CD105. These MSCs exhibited low ability in chondrogenic dif- ferentiation, which can potentially be attributed to their lack of CD105 expression. Lack of expression of CD45 showed evidence of absence of hematopoietic stem cells. Conclusion: This study showed that murine compact bone-chip culture can yield MSCs with significant proliferation ca- pacity. The cells displayed the ability to differentiate into osteoblast and adipocyte lineages.

Growth and potential damage of human bone-derived cells cultured on fresh and aged C60/Ti films.

Thin films of binary C60/Ti composites, with various concentrations of Ti ranging from ~ 25% to ~ 70%, were deposited on microscopic glass coverslips and were tested for their potential use in bone tissue engineering as substrates for the adhesion and growth of bone cells. The novelty of this approach lies in the combination of Ti atoms (i.e., widely used biocompatible material for the construction of stomatological and orthopedic implants) with atoms of fullerene C60, which can act as very efficient radical scavengers. However, fullerenes and their derivatives are able to generate harmful reactive oxygen species and to have cytotoxic effects. In order to stabilize C60 molecules and to prevent their possible cytotoxic effects, deposition in the compact form of Ti/C60 composites (with various Ti concentrations) was chosen. The reactivity of C60/Ti composites may change in time due to the physicochemical changes of molecules in an air atmosphere. In this study, we therefore tested the dependence between the age of C60/Ti films (from one week to one year) and the adhesion, morphology, proliferation, viability, metabolic activity and potential DNA damage to human osteosarcoma cells (lines MG-63 and U-2 OS). After 7 days of cultivation, we did not observe any negative influence of fresh or aged C60/Ti layers on cell behavior, including the DNA damage response. The presence of Ti atoms resulted in improved properties of the C60 layers, which became more suitable for cell cultivation.

Upregulation of cell proliferation via Shc and ERK1/2 MAPK signaling in SaOS-2 osteoblasts grown on magnesium alloy surface coating with tricalcium phosphate.

Magnesium (Mg) alloys have been demonstrated to be viable orthopedic implants because of mechanical and biocompatible properties similar to natural bone. In order to improve its osteogenic properties, a porous β-tricalcium phosphate (β-TCP) was coated on the Mg-3AI-1Zn alloy by alkali-heat treatment technique. The human bone-derived cells (SaOS-2) were cultured on (β-TCP)-Mg-3AI-1Zn in vitro, and the osteoblast response, the morphology and the elements on this alloy surface were investigated. Also, the regulation of key intracellular signalling proteins was investigated in the SaOS-2 cells cultured on alloy surface. The results from scanning electron microscope and immunofluorescence staining demonstrated that (β-TCP)-Mg-3AI-1Zn induced significant osteogenesis. SaOS-2 cell proliferation was improved by β-TCP coating. Moreover, the (β-TCP)-Mg-3AI-1Zn surface induced activation of key intracellular signalling proteins in SaOS-2 cells. We observed an enhanced activation of Src homology and collagen (Shc), a common point of integration between bone morphogenetic protein 2, and the Ras/mitogen-activated protein kinase (MAPK) pathway. ERK1/2 MAP kinase activation was also upregulated, suggesting a role in mediating osteoblastic cell interactions with biomaterials. The signalling pathway involving c-fos (member of the activated protein-1) was also shown to be upregulated in osteoblasts cultured on the (β-TCP)-Mg-3AI-1Zn. These results suggest that β-TCP coating may contribute to successful osteoblast function on Mg alloy surface. (β-TCP)-Mg-3AI-1Zn may upregulate cell proliferation via Shc and ERK1/2 MAPK signaling in SaOS-2 osteoblasts grown on Mg alloy surface.

Induction of creatine kinase release from cultured osteoclasts via the pharmacological action of aminobisphosphonates.

An increase of serum creatine kinase (CK) has been observed in clinical studies of nitrogen-containing aminobisphosphonates (N-BPs). Osteoclasts are thought to be the source of the CK, but there is no clear evidence for the hypothesis. In this study, CK release from rabbit osteoclasts induced by N-BPs was examined in an in vitro culture system. Rabbit bone-derived cells were cultured for 3 days on the N-BPs pretreated cortical bone slices. CK activity in the culture medium was measured at 3 days of culture. The CK activity was increased with all N-BPs at concentrations at which showed antiresorptive activity over 60% inhibition of C-terminal cross-linking telopeptide of type I collagen (CTX-1) release. The maximum induction of CK activity was 2.6 times the control level. The lowest N-BP concentration inducing CK release was 3 times lower than that required to decrease the osteoclast number. Bafilomycin A1, an inhibitor of vacuolar H+-ATPase, abrogated all N-BP actions, including CK release. Bone-derived cells except osteoclasts were insensitive to bafilomycin A1, suggesting that osteoclasts were the source of CK. Regarding the time course, CK release occurred after a 1 day lag time and increased steadily until day 3 of culture. These results show that CK release is induced by N-BPs from osteoclasts at concentrations at which N-BPs show antiresorptive activity over 60% inhibition of CTX-1 release in vitro. These findings explain the mechanism of the CK increase induced by clinical use of N-BPs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-015-0848-3) contains supplementary material, which is available to authorized users.

α2β1 integrin-mediated mechanical signals during osteodifferentiation of stem cells from the Wharton's jelly of the umbilical cord.

The formation and maintenance of tissues is regulated by various signals triggered by biological, chemical, and physical factors. Data increasingly confirm that matrix or tissue elasticity plays an influential role in regulating numerous cell functions. The aim of the present study was to better understand the regulation of cellular differentiation by mechanical cues. We studied the influence of matrix stiffness on the osteodifferentiation of two cell lineages characterized by different responses: mesenchymal stromal/stem cells isolated from the Wharton's jelly of the umbilical cord (UC-MSCs) with strong stiffness-dependent responses; and bone-derived cells (BDCs), which are insensitive to changes in matrix rigidity. The study also aimed to delineate how matrix stiffness affects intracellular signaling through focal adhesion kinase (FAK) activity—one of the key components in integrin-mediated signaling pathways. The effect of substrate stiffness on the expression of α2, α5, and β1 integrin was studied using real time PCR and Western blot using cells cultured in an osteogenic medium on tunable polyacrylamide gels coated with type I collagen, with elasticities corresponding to Young's moduli of 1.46 kPa and 26.12 kPa. FAK activity was monitored using ELISA assays. We demonstrate for the first time the changes in the expression of α2, α5, and β1 integrin subunits in perinatal stem cells and in adult osteoblast precursor cells during in vitro osteogenic differentiation on surfaces characterized by different stiffness. We found that matrix rigidity significantly affects the osteogenic differentiation of UC-MSCs through α2 integrin-mediated mechanotransduction events, though not through the α5 integrin subunit. In BDCs, there were no significant changes in the expression levels of the tested protein associated with varying stiffness. Our results provide evidence that matrix rigidity affects the osteogenic differentiation of UC-MSCs via mechanotransduction events mediated by α2 integrin subunits.

BMP4: a Possible Key Factor in Differentiation of Auditory Neuron-Like Cells from Bone-Derived Mesenchymal Stromal Cells.

Previous studies have shown that BMP4 may play an important part in the development of auditory neurons (ANs), which are degenerated in sensorineural hearing loss. However, whether BMP4 can promote sensory fate specification from mesenchymal stromal cells (MSCs) is unknown so far. MSCs isolated from Sprague-Dawley (SD) rats were confirmed by expression of MSC markers using flow cytometry and adipogenesis/osteogenesis using differentiation assays. MSCs treated with a complex of neurotrophic factors (BMP4 group and non-BMP4 group) were induced into auditory neuron-like cells, then the differences between the two groups were analyzed in morphological observation, cell growth curve, qRT-PCR, and immunofluorescence. Flow cytometric analysis showed that the isolated cells expressed typical MSC surface markers. After adipogenic and osteogenic induction, the cells were stained by oil red O and Alizarin Red. The neuronal induced cells were in the growth plateau and had special forms of neurons. In the presence of BMP4, the inner ear genes NF-M, Neurog1, GluR4, NeuroD, Calretinin, NeuN, Tau, and GATA3 were up-regulated in MSCs. MSCs have the capacity to differentiate into auditory neuron-like cells in vitro. As an effective inducer, BMP4 may play a key role in transdifferentiation.

Abstract 3349: Crosstalk between Runx2 regulatory network and insulin-like growth factor receptor/Akt signaling pathway in bone metastasis of breast cancer

Abstract The metastasis of breast cancer cells to bones is a leading cause of cancer-related deaths. The bone microenvironment presents a vital source of several growth factors that could promote survival and proliferation of metastatic cancer cells. The bone-derived insulin-like growth factor-1 (IGF-1) binds to insulin-like growth factor receptor (IGF-1R) to initiate intracellular signaling. The downstream signaling events in response to IGF-1R stimulation include activation of Phosphatidyl Inositol 3’ Kinase (PI3K) and Mitogen Activated Protein Kinase (MAPK) pathways. However, the inhibition of these signaling pathways has shown modest benefit in recent clinical trials necessitating the need to identify regulatory mechanisms to successfully block breast cancer-associated bone metastasis. The Runt-related transcription factor, Runx2, is required for normal bone development but is also aberrantly expressed at higher levels in invasive mammary epithelial cells and promotes invasive properties. Previously, we have identified a mechanism wherein Runx2 promotes survival of parental population of invasive breast cancer MDA-MB-231cells by promoting phosphorylation of serine/threonine kinase Akt (pAkt) via mammalian target of rapamycin complex-2 proteins. To determine the implications of Runx2-mediated pAkt regulation in bone metastasis of breast cancers, we harvested Runx2 knockdown or control MDA-MB-231 cells from bones 7 weeks post intracardiac injections in NOD/SCID mice. The gene and protein expression levels of IGF-1R/Akt pathway effectors in the bone seeking subpopulation were determined by real-time PCR and western blotting approaches. The bone-derived Runx2 knockdown cells showed increased IGF-1Rβ levels compared to controls. The Runx2 knockdown MDA-MB-231 cells showed an increase in pIGF1R-β and pAkt levels in response to IGF-1 stimulation that could be inhibited with IGF-1Rβ inhibitor OSI-906 (Linsitinib). However, despite inhibition of IGF-1R and Akt activity with OSI-906 treatment, no alterations were observed in growth or survival of bone-seeking cells. Interestingly, in contrast to IGF-1Rβ and pAkt, the Erk 1/2 levels were reduced in bone-derived Runx2 knockdown MDA-MB-231 cells compared to parental MDA-MB-231 cells. The treatment of cells with Erk 1/2 inhibitor PD184161 reduced cell proliferation and clonogenic potential. Furthermore, the Runx2 protein levels were also reduced in bone seeking subpopulation compared to parental MDA-MB-231cells. Taken together, our studies indicate Runx2-mediated suppression of IGF-1Rβ and Akt but upregulation of Erk signaling in bone seeking breast cancer cells compared to parental MDA-MB-231 cells. Our results suggest that the growth of bone metastatic cancer cells could be effectively blocked by inhibition of Runx2 and Erk pathway. Citation Format: Manish Tandon, Zujian Chen, Jitesh Pratap. Crosstalk between Runx2 regulatory network and insulin-like growth factor receptor/Akt signaling pathway in bone metastasis of breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3349. doi:10.1158/1538-7445.AM2014-3349

2-(Dimethylamino)ethyl Methacrylate/(2-Hydroxyethyl) Methacrylate/α-Tricalcium Phosphate Cryogels for Bone Repair, Preparation and Evaluation of the Biological Response of Human Trabecular Bone-Derived Cells and Mesenchymal Stem Cells

The aim of this work is to evaluate the potential of cryogels to be used as scaffolds in tissue engineering. Scaffolds based on the α-tricalcium phosphate reinforced PDMAEMA (Poly(dimethyl aminoethyl methacrylate))/PHEMA (poly(hydroxyethyl methacrylate)) system were prepared and human trabecular bone-derived cells (HTBs) and bone marrow derived-mesenchymal stem cells (BM-MSCs) cultured on them. Several features, such as porosity, pore shape, molecular weight between crosslinks and mesh size, are studied. The most suitable PDMAEMA/PHEMA ratio for cell proliferation has been assessed and the viability, adhesion, proliferation and expression of osteoblastic biochemical markers are evaluated. The PDMAEMA/PHEMA ratio influences the scaffolds porosity. Values between 53% ± 5.7% for a greater content in PHEMA and 75% ± 5.5% for a greater content in PDMAEMA have been obtained. The polymer ratio also modifies the pore shape. A greater content in PDMAEMA leads also to bigger network mesh size. Each of the compositions were non-cytotoxic, the seeded cells remained viable for both BM-MSCs and HTBs. Thus, and based on the structural analysis, specimens with a greater content in PDMAEMA seem to provide a better structural environment for their use as scaffolds for tissue engineering. The α-tricalcium phosphate incorporation into the composition seems to favor the expression of the osteogenic phenotype.

Cell Models Adapted to Real-Time Imaging of the Cytoskeleton Dynamics in Altered Gravity

Spatial and temporal regulation of cell phenotype by mechanical forces is a growing field of research in health sciences since these stimuli influence cellular functions, such as proliferation, migration, differentiation and gene expression. In the context of the Fluolive project selected by the European Space Agency and aiming at evaluating the impact of gravity alterations on the cell phenotype, we have developed new bone-derived cell lines adapted for live-cell imaging of the cytoskeleton. Osteoblastic cells derived from human osteosarcomas were used as experimental models. U2-OS and SaoS-2 cells stably expressing TagGFP2- β-actin and mCherry- α-tubulin were established and single-cell clonal cultures were characterized in terms of recombinant proteins production and localization, fluorescence intensity, cell proliferation and migration rates. Living fluorescently-tagged cell lines allow real-time fluorescence microscopy of the cytoskeleton dynamics without bleaching and without alteration of cell morphology. U2-OS and SaoS-2 TagGFP2- β-actin and mCherry- α-tubulin clones will be used to monitor the effect of mechanical forces in models of altered gravity on Earth and possibly on the ISS.

MiR-29a is an enhancer of mineral deposition in bone-derived systems

MicroRNAs (miRNAs) provide a mechanism for fine-tuning of intricate cellular processes through post-transcriptional regulation. Emerging evidences indicate that miRNAs play key roles in regulation of osteogenesis. The miR-29 family was previously implicated in mammalian osteoblast differentiation by targeting extracellular matrix molecules and modulating Wnt signaling. Nevertheless, the function of miR-29 in bone formation and homeostasis is not completely understood. Here, we provide novel insights into the biological effect of miR-29a overexpression in a mineralogenic cell system (ABSa15). MiR-29a gain-of-function resulted in significant increase of extracellular matrix mineralization, probably due to accelerated differentiation. We also demonstrated for the first time that miR-29a induced β-catenin protein levels, implying a stimulation of canonical Wnt signaling. Our data also suggests that SPARC is a conserved target of miR-29a, and may contribute to the phenotype observed in ABSa15 cells. Finally, we provide evidences for miR-29a conservation throughout evolution based on sequence homology, synteny analysis and expression patterns. Concluding, miR-29a is a key player in osteogenic differentiation, leading to increased mineralization in vitro, and this function seems to be conserved throughout vertebrate evolution by interaction with canonical Wnt signaling and conservation of targets.

A functional biphasic biomaterial homing mesenchymal stem cells for in vivo cartilage regeneration

Cartilage regeneration after trauma is still a great challenge for clinicians and researchers due to many reasons, such as joint load-bearing, synovial movement and the paucity of endogenous repair cells. To overcome these limitations, we constructed a functional biomaterial using a biphasic scaffold platform and a bone-derived mesenchymal stem cells (BMSCs)-specific affinity peptide. The biphasic scaffold platform retains more cells homogeneously within the sol–gel transition of chitosan and provides sufficient solid matrix strength. This biphasic scaffold platform is functionalized with an affinity peptide targeting a cell source of interest, BMSCs. The presence of conjugated peptide gives this system a biological functionality towards BMSC-specific homing both in vitro and in vivo. The functional biomaterial can stimulate stem cell proliferation and chondrogenic differentiation during in vitro culture. Six months after in vivo implantation, compared with routine surgery or control scaffolds, the functional biomaterials induced superior cartilage repair without complications, as indicated by histological observations, magnetic resonance imaging and biomechanical properties. Beyond cartilage repair, this functional biphasic scaffold may provide a biomaterial framework for one-step tissue engineering strategy by homing endogenous cells to stimulate tissue regeneration.

부자(附子)와 오가피(五加皮) 물 추출물의 골수유래 지방세포와 파골세포 분화 억제 효과

Objectives : The aim of this study was to evaluate the efficacy of Aconiti Lateralis Preparata Radix (AP) and Acanthopanacis Cortex (AT) extracts in bone-derived adipocyte OP9 cell, osteoclast and osteoblast-like MG63 cells. Methods : MTT assay was used to evaluate the cytotoxicity of AP and AT extracts on OP9, osteoclast and MG63 cells. OP9 cells were treated with AP and AT, and the alterations in fat storage in the cells were determined by the Oil red O. To explain effects of RANKL-induced osteoclast differentiation in bone marrow macrophages, we performed the TRAP staining. The protein level of CAAAT/enhancer binding protein alpha (<TEX>$C/EBP{\alpha}$</TEX>) and peroxisome proliferator-activated receptor <TEX>${\gamma}$</TEX> (<TEX>$PPAR{\gamma}$</TEX>) as a adipocyte differentiation marker, and adiponectin was examined using western blot in differentiated OP9 cells. Effects of related genes were confirmed by luciferase assay using reporter assay. Results : AP and AT was not toxic on OP9 and MG63 cells, but AT was a little cytotoxic to osteoclast at the dose of <TEX>$100{\mu}g/m{\ell}$</TEX>. They could inhibit differentiation of OP9 cells and osteoclast with results of oil red O staining and TRAP staining. By western blot, AP and AT decreased the expression of <TEX>$PPAR{\gamma}$</TEX> and <TEX>$C/EBP{\alpha}$</TEX> which is the key transcription factor in adipogenesis and adiponectin secretion. AT also inhibited the BMP-4 activity in luciferase assay. AP also inhibited BMP-4 and Wnt3a activity, stimulated ER-<TEX>${\beta}$</TEX> activity but inhibited androgen receptor activity. Conclusions : These results show AP and AT can be useful in osteoporosis and obesity via inhibition of osteoclast and adipocyte differentiation.

Bone marrow stromal cells on a three-dimensional bioactive fiber mesh undergo osteogenic differentiation in the absence of osteogenic media supplements: The effect of silanol groups

Osteogenic differentiation is a tightly regulated process dependent on the stimuli provided by the micro-environment. Silicon-substituted materials are known to have an influence on the osteogenic phenotype of undifferentiated and bone-derived cells. This study aims to investigate the bioactivity profile as well as the mechanical properties of a blend of starch and poly-caprolactone (SPCL) polymeric fiber mesh scaffolds functionalized with silanol (Si–OH) groups as key features for bone tissue engineering strategies. The scaffolds were made from SPCL by a wet spinning technique. A calcium silicate solution was used as a non-solvent to develop an in situ functionalization with Si–OH groups in a single-step approach. We also explored the relevance of silicon incorporated in SPCL–Si scaffolds to the in vitro osteogenic process of goat bone marrow stromal cells (gBMSCs) with and without osteogenic supplements in the culture medium. We hypothesized that SPCL–Si scaffolds could act as physical and chemical millieus to induce per se the osteogenic differentiation of gBMSCs. Results show that osteogenic differentiation of gBMSCs and the production of a mineralized extracellular matrix on bioactive SPCL–Si scaffolds occur for up to 2weeks, even in the absence of osteogenic supplements in the culture medium. The omission of media supplements to induce osteogenic differentiation is a promising feature towards simplified and cost-effective cell culturing procedures of a potential bioengineered product, and concomitant translation into the clinical field. Thus, the present work demonstrates that SPCL–Si scaffolds and their intrinsic properties sustain gBMSC osteogenic features in vitro, even in the absence of osteogenic supplements to the culture medium, and show great potential for bone regeneration strategies.

Directing chondrogenic differentiation of mesenchymal stem cells with a solid-supported chitosan thermogel for cartilage tissue engineering

Hydrogels are attractive for cartilage tissue engineering because of their high plasticity and similarity with the native cartilage matrix. However, one critical drawback of hydrogels for osteochondral repair is their inadequate mechanical strength. To address this limitation, we constructed a solid-supported thermogel comprising a chitosan hydrogel system and demineralized bone matrix. Scanning electron microscopy, the equilibrium scanning ratio, the biodegradation rate, biomechanical tests, biochemical assays, metabolic activity tests, immunostaining and cartilage-specific gene expression analysis were used to evaluate the solid-supported thermogel. Compared with pure hydrogel or demineralized matrix, the hybrid biomaterial showed superior porosity, equilibrium swelling and degradation rate. The hybrid scaffolds exhibited an increased mechanical strength: 75% and 30% higher compared with pure hydrogels and demineralized matrix, respectively. After three days culture, bone-derived mesenchymal stem cells (BMSCs) maintained viability above 90% in all three materials; however, the cell retention of the hybrid scaffolds was more efficient and uniform than the other materials. Matrix production and chondrogenic differentiation of BMSCs in the hybrid scaffolds were superior to its precursors, based on glycosaminoglycan quantification and hyaline cartilage marker expression after three weeks in culture. Its easy preparation, favourable biophysical properties and chondrogenic capacity indicated that this solid-supported thermogel could be an attractive biomaterial framework for cartilage tissue engineering.

Steven Houser: the beat goes on.

During 36 years at Temple University in Philadelphia, Steven Houser has been a leader in advancing scientific understanding of heart function. All along, he’s been driven by a desire to understand his father’s fatal heart disease, and to contribute important insights to help future patients. Steven Houser Houser and his collaborators—along with others in the field, he is quick to note—have shed light on numerous fundamental questions about how calcium regulates the beating of cardiomyocytes, including elucidating the details of calcium-induced calcium release.1,2 His research is probing calcium-dependent signaling pathways, aberrations in the hypertrophic, failing, or post-myocardial infarction heart,3–6 factors related to myocyte turnover,7 and potential treatment strategies including gene and stem cell therapy. Houser’s lab recently demonstrated that cortical bone-derived stem cells may be superior to cardiac stem cells in regenerating heart tissue after MI.8 Houser, 63, director of the Cardiovascular Research Center and chair of physiology at Temple, tells Circulation Research he’s never afraid to jump into a scientific argument9 and help inform the debate. His strategy is always fair and careful experimentation, with an emphasis on reproducible findings. “I think the results from my group have stood the test of time,” he says. “That’s one of the things I’m proudest of—that our work can be repeated.” I grew up in New Jersey, in a little town called Magnolia, about 10 miles from Philadelphia, in suburban housing built primarily for soldiers returning after World War II. My dad had been in the service. [He] was a working guy. Mom stayed home, tried to keep me in line. My dad worked for a company called Western Electric. He was a wireman. My mom ended up going to college when I started high school. To help pay my way through college, …

Human Immunodeficiency Virus Type 1 Enhancer-binding Protein 3 Is Essential for the Expression of Asparagine-linked Glycosylation 2 in the Regulation of Osteoblast and Chondrocyte Differentiation

Human immunodeficiency virus type 1 enhancer-binding protein 3 (Hivep3) suppresses osteoblast differentiation by inducing proteasomal degradation of the osteogenesis master regulator Runx2. In this study, we tested the possibility of cooperation of Hivep1, Hivep2, and Hivep3 in osteoblast and/or chondrocyte differentiation. Microarray analyses with ST-2 bone stroma cells demonstrated that expression of any known osteochondrogenesis-related genes was not commonly affected by the three Hivep siRNAs. Only Hivep3 siRNA promoted osteoblast differentiation in ST-2 cells, whereas all three siRNAs cooperatively suppressed differentiation in ATDC5 chondrocytes. We further used microarray analysis to identify genes commonly down-regulated in both MC3T3-E1 osteoblasts and ST-2 cells upon knockdown of Hivep3 and identified asparagine-linked glycosylation 2 (Alg2), which encodes a mannosyltransferase residing on the endoplasmic reticulum. The Hivep3 siRNA-mediated promotion of osteoblast differentiation was negated by forced Alg2 expression. Alg2 suppressed osteoblast differentiation and bone formation in cultured calvarial bone. Alg2 was immunoprecipitated with Runx2, whereas the combined transfection of Runx2 and Alg2 interfered with Runx2 nuclear localization, which resulted in suppression of Runx2 activity. Chondrocyte differentiation was promoted by Hivep3 overexpression, in concert with increased expression of Creb3l2, whose gene product is the endoplasmic reticulum stress transducer crucial for chondrogenesis. Alg2 silencing suppressed Creb3l2 expression and chondrogenesis of ATDC5 cells, whereas infection of Alg2-expressing virus promoted chondrocyte maturation in cultured cartilage rudiments. Thus, Alg2, as a downstream mediator of Hivep3, suppresses osteogenesis, whereas it promotes chondrogenesis. To our knowledge, this study is the first to link a mannosyltransferase gene to osteochondrogenesis.

Amyloid‐Hydroxyapatite Bone Biomimetic Composites

A "bottom up" strategy is proposed to synthesize high aspect ratio hydroxyapatite (and brushite) platelets, and combine them with amyloid fibrils into layered hybrid nanocomposites. Their hierarchical structure, despite the differences from natural bone, confers to the nanocomposites a density and elastic modulus matching those of cancellous bone. Evidence of good adhesion and spreading of human trabecular bone-derived pre-osteoblasts cells on these nanocomposites is provided.

Suppressive effect of compact bone-derived mesenchymal stem cells on chronic airway remodeling in murine model of asthma

New therapeutic strategies are needed in the treatment of asthma besides vaccines and pharmacotherapies. For the development of novel therapies, the use of mesenchymal stem cells (MSCs) is a promising approach in regenerative medicine. Delivery of compact bone (CB) derived MSCs to the injured lungs is an alternative treatment strategy for chronic asthma. In this study, we aimed to isolate highly enriched population of MSCs from mouse CB with regenerative capacity, and to investigate the impact of these cells in airway remodeling and inflammation in experimental ovalbumin-induced mouse model of chronic asthma. mCB-MSCs were isolated, characterized, labeled with GFP and then transferred into mice with chronic asthma developed by ovalbumin (OVA) provocation. Histopathological changes including basement membrane, epithelium, subepithelial smooth thickness and goblet cell hyperplasia, and MSCs migration to lung tissues were evaluated. These histopathological alterations were increased in ovalbumin-treated mice compared to PBS group (P<0.001). Intravenous administration of mCB-MSC significantly reduced these histopathological changes in both distal and proximal airways (P<0.001). We showed that GFP-labeled MSCs were located in the lungs of OVA group 2weeks after intravenous induction. mCB-MSCs also significantly promoted Treg response in ovalbumin-treated mice (OVA+MSC group) (P<0.037). Our studies revealed that mCB-MSCs migrated to lung tissue and suppressed histopathological changes in murine model of asthma. The results reported here provided evidence that mCB-MSCs may be an alternative strategy for the treatment of remodeling and inflammation associated with chronic asthma.

Effect of Treadmill Exercise Timing on Repair of Full-Thickness Defects of Articular Cartilage by Bone-Derived Mesenchymal Stem Cells: An Experimental Investigation in Rats

ObjectiveCurrent medical practice for the treatment of articular cartilage lesions remains a clinical challenge due to the limited self-repair ability of articular cartilage. Both experimental and clinical researches show that moderate exercise can improve articular cartilage repair process. However, optimal timing of moderate exercise is unclear. We aimed to evaluate the effect of timing of moderate treadmill exercise on repair of full-thickness defects of articular cartilage.DesignFull-thickness cartilage defects were drilled in the patellar groove of bilateral femoral condyles in a total of 40 male SD rats before they were randomly assigned into four even groups. In sedentary control (SED) group, no exercise was given; in 2-week (2W), 4-week (4W) and 8-week groups, moderate treadmill exercise was initiated respectively two, four and eight weeks after operation. Half of the animals were sacrificed at week 10 after operation and half at week 14 after operation. Femoral condyles were harvested for gross observation and histochemical measurement by O'Driscoll scoring system. Collagen type II was detected by immunohistochemistry and mRNA expressions of aggrecan and collagen type II cartilage by RT-PCR.ResultsBoth 10 and 14 weeks post-operation, the best results were observed in 4W group and the worst results appeared in 2W group. The histochemistry scores and the expressions of collagen type II and aggrecan were significantly higher in 4W group than that in other three groups (P<0.05).ConclusionsModerate exercise at a selected timing (approximately 4 weeks) after injury can significantly promote the healing of cartilage defects but may hamper the repair process if performed too early while delayed intervention by moderate exercise may reduce its benefits in repair of the defects.