OBJECTIVETo study the characteristics of mandible and condyle in Dmp1 gene knockout mice, and to investigate the role of Dmp1 in the osteogenesis and mineralization of bone and cartilage.

METHODSDmp1-/-mice were executed at birth, 2 weeks, 2 months, 3 months and 5 months, and the mandible was taken out for physical, radiography, transmission electron microscopic, and histological examination. The difference between Dmp1 knockout mouse (ko) and wild type mouse (wt) in bone development, bone densitometry and histology were compared.

RESULTSThere were obvious changes in the mandible and condyle of Dmp1-/-mouse, such as incomplete ossification, low density, decreased volume and condyle cartilage degeneration.

CONCLUSIONSDmp1 is the key factor in the formation of growth plates and secondary ossification center, and plays an important role in the process of bone and cartilage formation and bone nodule remodeling. Dmp1 may be the candidate gene that controls the development of mandible and cartilage.

Animals ; Bone Demineralization, Pathologic ; genetics ; pathology ; Chondrogenesis ; genetics ; Extracellular Matrix Proteins ; genetics ; Gene Knockout Techniques ; Mandible ; pathology ; Mandibular Condyle ; pathology ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Osteogenesis ; genetics

A new type of TGF-β3 fusion protein with targeted therapy function was constructed, and its feasibility and target specificity of inducing chondrogenesis were investigated by transfecting LAP-MMP-mTGF-β3 gene into adipose-derived stem cells (ADSCs). The recombinant pIRES-EGFP-MMP was constructed by inserting the sense and antisense DNA of encoding the amino acid of the synthetic MMP enzyme cutting site into the eukaryotic expression vector pIRES-EGFP. LAP and mTGF-β3 fragments were obtained by using RT-PCR and inserted into the upstream and downstream of MMP from pIRES-EGFP-MMP respectively, and the recombinant plasmid of pIRES-EGFP-LAP-MMP-mTGF-β3 was constructed, which was transferred to ADSCs. The ADSCs were cultured and divided in three groups: experimental group (MMP group), negative control group (no MMP) and non-transfection group. The morphological changes were observed microscopically, and the expression of proteoglycan and type II collagen (ColII) was detected by using Alcian blue staining and immunohistochemistry staining at 7th, 14th and 21st day after culture. The recombinant plasmid of pIRES-EGFP-LAP-MMP-mTGF-β3 was correctly constructed by methods of enzyme cutting and sequencing analysis. The mTGF-β3 fusion protein was successfully expressed after transfection, and in the presence of the MMP, active protein mTGF-β3 was generated, which significantly promoted differentiation of ADSCs into chondrocytes and the expression of cartilage matrix. The novel fusion protein LAP-MMP-mTGF-β3 can targetedly induce differentiation of ADSCs into chondrocytes, which would open up prospects for target therapy of cartilage damage repair in future.
Adipose Tissue ; metabolism ; Animals ; Chondrogenesis ; genetics ; Female ; Male ; Rabbits ; Recombinant Fusion Proteins ; genetics ; metabolism ; Stem Cells ; metabolism ; Transforming Growth Factor beta3 ; genetics ; metabolism

Mesenchymal stem cells (MSCs) are progenitors of connective tissues, which have emerged as important tools for tissue engineering due to their differentiation potential along various cell types. In recent years, accumulating evidence has suggested that the regulation of mitochondria dynamics and function is essential for successful differentiation of MSCs. In this paper, we review and provide an integrated view on the role of mitochondria in MSC differentiation. The mitochondria are maintained at a relatively low activity level in MSCs, and upon induction, mtDNA copy number, protein levels of respiratory enzymes, the oxygen consumption rate, mRNA levels of mitochondrial biogenesis-associated genes, and intracellular ATP content are increased. The regulated level of mitochondrial ROS is found not only to influence differentiation but also to contribute to the direction determination of differentiation. Understanding the roles of mitochondrial dynamics during MSC differentiation will facilitate the optimization of differentiation protocols by adjusting biochemical properties, such as energy production or the redox status of stem cells, and ultimately, benefit the development of new pharmacologic strategies in regenerative medicine.
Adipogenesis ; physiology ; Animals ; Cell Differentiation ; physiology ; Chondrogenesis ; physiology ; Humans ; Mesenchymal Stem Cells ; cytology ; metabolism ; Mitochondria ; genetics ; metabolism ; Mitochondrial Proteins ; genetics ; metabolism ; Osteogenesis ; physiology ; RNA ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; RNA, Mitochondrial ; Reactive Oxygen Species ; metabolism

Mouse embryonic stem (mES) cells are capable of undergoing chondrogenesis in vitro. To enhance this process, the human SOX9 (hSOX9) cDNA was delivered into mES cells and the clones overexpressing hSOX9 (denoted as mES-hSOX9 cells) were verified by Western blot analysis. The transcripts of collagen IIA (a juvenile form), aggrecan and Pax1 were expressed in mES-hSOX9 cells grown on feeder layers, suggesting the immediate effect of exogenous SOX9 on chondrogenesis. However, SOX9 overexpression did not affect the cell cycle distribution in undifferentiated mES cells. Upon differentiation, collagen IIB (an adult form) was detected in day 3 immature embryoid bodies. In addition, the overexpression of exogenous SOX9 significantly induced transcriptional activity driven by SOX9 binding site. Taken together, we for the first time demonstrated that constitutive overexpression of exogenous SOX9 in undifferentiated mES cells might have dual potentials to induce both chondrogenic commitment and growth capacity in the undifferentiated status.
Animals ; Cell Differentiation/genetics ; Cell Line ; *Chondrogenesis ; Collagen Type II/genetics ; Embryo/*cytology ; Enhancer Elements (Genetics)/genetics ; Extracellular Matrix Proteins/genetics ; Genetic Markers/genetics ; High Mobility Group Proteins/genetics/*metabolism ; Humans ; Lectins, C-Type/genetics ; Mice ; Paired Box Transcription Factors/genetics ; Proteoglycans/genetics ; Research Support, Non-U.S. Gov't ; Stem Cells/*metabolism/physiology ; Trans-Activation (Genetics) ; Transcription Factors/genetics/*metabolism

Cyclooxygenase-2 (COX-2) is known to modulate bone metabolism, including bone formation and resorption. Because cartilage serves as a template for endochondral bone formation and because cartilage development is initiated by the differentiation of mesenchymal cells into chondrocytes (Ahrens et al., 1977; Sandell and Adler, 1999; Solursh, 1989), it is of interest to know whether COX-2 expression affect chondrocyte differentiation. Therefore, we investigated the effects of COX-2 protein on differentiation in rabbit articular chondrocyte and chick limb bud mesenchymal cells. Overexpression of COX-2 protein was induced by the COX-2 cDNA transfection. Ectopic expression of COX-2 was sufficient to causes dedifferentiation in articular chondrocytes as determined by the expression of type II collagen via Alcian blue staining and Western blot. Also, COX-2 overexpression caused suppression of SOX-9 expression, a major transcription factor that regulates type II collagen expression, as indicated by the Western blot and RT-PCR. We further examined ectopic expression of COX-2 in chondrifying mesenchymal cells. As expected, COX-2 cDNA transfection blocked cartilage nodule formation as determined by Alcian blue staining. Our results collectively suggest that COX-2 overexpression causes dedifferentiation in articular chondrocytes and inhibits chondrogenic differentiation of mesenchymal cells.
Animals ; Cartilage, Articular/cytology ; Cell Differentiation ; Cells, Cultured ; Chick Embryo ; Chondrocytes/*cytology/enzymology ; Chondrogenesis ; Collagen Type II/metabolism ; Cyclooxygenase 2/*biosynthesis/genetics ; Interleukin-1beta/pharmacology ; Mesenchymal Stem Cells/*cytology/enzymology ; Rabbits ; SOX9 Transcription Factor/metabolism

Chondrogenesis involves the recruitment of mesenchymal cells to differentiate into chondroblasts, and also the cells must synthesize a cartilage-specific extracellular matrix. There were two representative culture systems that promoted the chondrogenic differentiation of human mesenchymal stem cells. These systems were adaptations of the "pellet" culture system, which was originally described as a method for preventing the phenotypic modulation of chondrocytes, and the "alginate bead" culture system, which was used to maintain encapsulated cells at their differentiated phenotype over time, and also it was used to maintain the cells' proteoglycan synthesis at a rate similar to that of primary chondrocytes. We performed test on the differences of phenotypic characterization with the two methods of differentiating human mesenchymal stem cells into chondrocytes. The typical gene for articular cartilage, collagen type II, was more strongly expressed in the "alginate bead" system than in the "pellet" culture system, in addition, specific gene for hypertrophic cartilage, collagen type X, was more rapidly expressed in the "pellet" system than in "alginate bead" culture system. Therefore, the "alginate bead" culture system is a more phenotypical, practical and appropriate system to differentiate human mesenchymal stem cells into articular chondrocytes than the "pellet" culture system.
Adult ; Alginates ; *Cell Differentiation ; *Chondrogenesis ; Collagen/genetics ; Comparative Study ; Glucuronic Acid ; Hexuronic Acids ; Humans ; Immunohistochemistry ; Mesenchymal Stem Cells/*cytology ; Phenotype ; Research Support, Non-U.S. Gov't ; Reverse Transcriptase Polymerase Chain Reaction ; Staining and Labeling

Mesenchymal stem cells (MSCs) have the capacity to proliferate and differentiate into multiple connective tissue lineages, which include cartilage, bone, and fat. Cartilage differentiation and chondrocyte maturation are required for normal skeletal development, but the intracellular pathways regulating this process remain largely unclear. This study was designed to identify novel genes that might help clarify the molecular mechanisms of chondrogenesis. Chondrogenesis was induced by culturing human bone marrow (BM) derived MSCs in micromass pellets in the presence of defined medium for 3, 7, 14 or 21 days. Several genes regulated during chondrogenesis were then identified by reverse transcriptase-polymerase chain reaction (RT-PCR). Using an ABI microarray system, we determined the differential gene expression profiles of differentiated chondrocytes and BM-MSCs. Normalization of this data resulted in the identification of 1,486 differentially expressed genes. To verify gene expression profiles determined by microarray analysis, the expression levels of 10 genes with high fold changes were confirmed by RT-PCR. Gene expression patterns of 9 genes (Hrad6B, annexinA2, BMP-7, contactin-1, peroxiredoxin-1, heat shock transcription factor-2, synaptotagmin IV, serotonin receptor-7, Axl) in RT-PCR were similar to the microarray gene expression patterns. These findings provide novel information concerning genes involved in the chondrogenesis of human BM-MSCs.
Bone Marrow Cells/*cytology ; Cell Differentiation ; Chondrocytes/metabolism ; Chondrogenesis/*genetics ; *Gene Expression Profiling ; Humans ; Mesenchymal Stem Cells/cytology/*metabolism ; Oligonucleotide Array Sequence Analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors

beta ig-h3 is a TGF-beta-induced extracellular matrix protein which is expressed in many tissues including bones and cartilages. In previous reports, we showed that beta ig-h3 mediates cell adhesion and migration and, especially in bones, negatively regulates the mineralization in the end stage of endochondral ossification. Here, to elucidate the expression pattern and role of beta ig-h3 in chondrocyte differentiation, ATDC5 chondrocytes and embryonic and postnatal mice were used for in vitro differentiation studies and in vivo studies, respectively. beta ig-h3 was strongly induced by the treatment of TGF-beta1 and the expression level of beta ig-h3 mRNA and protein were highly expressed in the early stages of differentiation but decreased in the late stages in ATDC5. Furthermore, the patterns of TGF-beta1, -beta2, and -beta3 mRNA expression were concurrent with beta ig-h3 in ATDC5. beta ig-h3 was deeply stained in perichondrium (PC), periosteum (PO), and prehypertrophic chondrocytes (PH) through the entire period of endochondral ossification in mice. beta ig-h3 was mainly expressed in PC and PH at embryonic days and obviously in PH in postnatal days. These results suggest that beta ig-h3 may play a critical role as a regulator of chondrogenic differentiation in endochondral ossification.
Animals ; Cell Differentiation/genetics ; Chondrocytes/*metabolism ; Chondrogenesis/*genetics ; Embryo, Mammalian ; Extracellular Matrix Proteins/*genetics/metabolism ; Femur/embryology/growth & development/metabolism ; Gene Expression Profiling ; Gene Expression Regulation, Developmental ; Mice ; Mice, Inbred ICR ; Osteogenesis/*genetics ; Transforming Growth Factor beta/*genetics/metabolism ; Tumor Cells, Cultured

It is widely known that hypoxia can promote chondrogenesis of human bone marrow derived mesenchymal stem cells (hMSCs) in monolayer cultures. However, the direct impact of oxygen tension on hMSC differentiation in three-dimensional cultures is still unknown. This research was designed to observe the direct impact of oxygen tension on the ability of hMSCs to "self assemble" into tissue-engineered cartilage constructs. hMSCs were cultured in chondrogenic medium (CM) containing 100 ng/mL growth differentiation factor 5 (GDF-5) at 5% (hypoxia) and 21% (normoxia) O2 levels in monolayer cultures for 3 weeks. After differentiation, the cells were digested and employed in a self-assembly process to produce tissue-engineered constructs under hypoxic and normoxic conditions in vitro. The aggrecan and type II collagen expression, and type X collagen in the self-assembled constructs were assessed by using immunofluorescent and immunochemical staining respectively. The methods of dimethylmethylene blue (DMMB), hydroxyproline and PicoGreen were used to measure the total collagen content, glycosaminoglycan (GAG) content and the number of viable cells in each construct, respectively. The expression of type II collagen and aggrecan under hypoxic conditions was increased significantly as compared with that under normoxic conditions. In contrast, type X collagen expression was down-regulated in the hypoxic group. Moreover, the constructs in hypoxic group showed more significantly increased total collagen and GAG than in normoxic group, which were more close to those of the natural cartilage. These findings demonstrated that hypoxia enhanced chondrogenesis of in vitro, scaffold-free, tissue-engineered constructs generated using hMSCs induced by GDF-5. In hypoxic environments, the self-assembled constructs have a Thistological appearance and biochemical parameters similar to those of the natural cartilage.
Aggrecans ; genetics ; metabolism ; Bone Marrow Cells ; drug effects ; metabolism ; Cartilage ; cytology ; metabolism ; Cell Differentiation ; drug effects ; genetics ; Cell Hypoxia ; Cells, Cultured ; Chondrogenesis ; drug effects ; genetics ; Collagen Type II ; genetics ; metabolism ; Collagen Type X ; metabolism ; Female ; Gene Expression ; drug effects ; Glycosaminoglycans ; metabolism ; Growth Differentiation Factor 5 ; pharmacology ; Humans ; Immunohistochemistry ; Male ; Mesenchymal Stromal Cells ; drug effects ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Tissue Engineering ; methods

The purpose of this study was to investigate the repair of the osteoarthritis(OA)-induced cartilage injury by transfecting the new TGF-β3 fusion protein (LAP-MMP-mTGF-β3) with targeted therapy function into the bone marrow-derived mesenchymal stem cells (MSCs) in rats. The recombinant of pIRES-EGFP-MMP was constructed by combination of DNA encoding MMP enzyme cutting site and eukaryotic expression vector pIRES-EGFP. LAP and mTGF-β3 fragments were obtained from rat embryos by RT-PCR and inserted into the upstream and downstream of MMP from pIRES-EGFP-MMP respectively, so as to construct the recombinant plasmid of pIRES-EGFP-LAP-MMP-mTGF-β3. pIRES-EGFP-LAP-MMP-mTGF-β3 was transfected into rat MSCs. The genetically modified MSCs were cultured in medium with MMP-1 or not. The transfected MSCs were transplanted in the rat OA models. The OA animal models were surgically induced by anterior cruciate ligament transaction (ACLT). The pathological changes were observed under a microscope by HE staining, Alcian blue, Safranin-fast Green and graded by Mankin's scale. pIRES-EGFP-LAP-MMP-mTGF-β3 was successfully constructed by means of enzyme cutting and sequencing, and the mTGF-β3 fusion protein (39 kD) was certified by Western blotting. Those genetically modified MSCs could differentiate into chondrocytes induced by MMP and secrete the relevant-matrix. The transfected MSCs could promote chondrogenesis and matrix production in rat OA models in vivo. It was concluded that a new fusion protein LAP-MMP-mTGF-β3 was constructed successfully by gene engineering, and could be used to repair the OA-induced cartilage injury.
Animals ; Base Sequence ; Blotting, Western ; Bone Marrow Cells ; metabolism ; Cartilage, Articular ; pathology ; surgery ; Cell Differentiation ; genetics ; Cells, Cultured ; Chondrocytes ; metabolism ; Chondrogenesis ; genetics ; Green Fluorescent Proteins ; genetics ; metabolism ; Matrix Metalloproteinases ; genetics ; metabolism ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stromal Cells ; metabolism ; Microscopy, Fluorescence ; Molecular Sequence Data ; Osteoarthritis ; surgery ; Rats ; Rats, Sprague-Dawley ; Recombinant Fusion Proteins ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Transfection ; Transforming Growth Factor beta3 ; genetics ; metabolism ; Treatment Outcome