title: Limitations of using aggrecan and type X collagen as markers of chondrogenesis in mesenchymal stem cell differentiation.
abstract: The study was initially designed to differentiate human bone marrow-derived mesenchymal stem cells (MSC) into chondrocyte-like cells, for use in tissue engineering. We cultured MSCs in defined chondrogenic medium as pellet cultures supplemented with transforming growth factor (TGF)-beta1 or -beta3 and dexamethazone, as they are commonly used to promote in vitro chondrogenesis. Markers of chondrogenesis used were type II collagen and aggrecan, with type X collagen being used as a marker of late-stage chondrocyte hypertrophy (associated with endochondral ossification). Our results show that aggrecan is constitutively expressed by MSCs and that type X collagen is expressed as an early event. Furthermore, we found that type X collagen was expressed before type II collagen in some cases. This is surprising because it is understood that stem cells have to be differentiated into chondrocytes before they can become hypertrophic. Thus, caution must be exercised when using aggrecan and type X collagen as markers for chondrogenesis and chondrocyte hypertrophy, respectively, in association with stem cell differentiation from this source.
authors.affiliation: Lady Davis Institute for Medical Research and Department of Surgery, SMBD-Jewish General Hospital, McGill University, Montreal, Quebec, Canada. fmwale@ldi.jgh.mcgill.ca
authors.forename: Fackson
authors.initials: F
authors.lastname: Mwale
authors.forename: Dorothy
authors.initials: D
authors.lastname: Stachura
authors.forename: Peter
authors.initials: P
authors.lastname: Roughley
authors.forename: John
authors.initials: J
authors.lastname: Antoniou
mesh_terms: D053674:Aggrecans; D015415:Biomarkers; D002454:Cell Differentiation / Q000502:physiology; D002469:Cell Separation / Q000379:methods*; D019902:Chondrocytes / Q000166:cytology; D020219:Chondrogenesis / Q000502:physiology; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics*; D024121:Collagen Type X / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D037181:Lectins, C-Type / Q000235:genetics*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D023822:Tissue Engineering / Q000379:methods
chemical_list: D053674:Aggrecans; D015415:Biomarkers; D011508:Chondroitin Sulfate Proteoglycans; D024121:Collagen Type X; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type