A predominantly articular cartilage-associated gene, SCRG1, is induced by glucocorticoid and stimulates chondrogenesis in vitro.
OBJECTIVE
Cartilage tissue engineering using multipotential human mesenchymal stem cells (hMSCs) is a promising approach to develop treatment for degenerative joint diseases. A key requirement is that the engineered tissues maintain their hyaline articular cartilage phenotype and not proceed towards hypertrophy. It is noteworthy that osteoarthritic articular cartilage frequently contains limited regions of reparative cartilage, suggesting the presence of bioactive factors with regenerative activity. Based on this idea, we recently performed cDNA microarray analysis to identify genes that are strongly expressed only in articular cartilage and encode secreted gene products. One of the genes that met our criteria was SCRG1. This study aims to analyze SCRG1 function in cartilage development using an in vitro mesenchymal chondrogenesis system.


METHODS
Full-length SCRG1 cDNA was subcloned into pcDNA5 vector, and transfected into hMSCs and murine C3H10T1/2 mesenchymal cells, placed in pellet cultures and micromass cultures, respectively. The cultures were analyzed by reverse transcription-polymerase chain reaction for the expression of SCRG1 and cartilage marker genes, and by histological staining for cartilage phenotype.


RESULTS
Induction of SCRG1 expression was seen during in vitro chondrogenesis, and was dependent on dexamethasone (DEX) known to promote chondrogenesis. Immunohistochemistry revealed that SCRG1 protein was localized to the extracellular matrix. Forced expression of SCRG1 in hMSCs suppressed their proliferation, and stimulated chondrogenesis in C3H10T1/2 cells, confirmed by reduced collagen type I and elevated collagen type IIB expression.


CONCLUSIONS
These results suggest that SCRG1 is involved in cell growth suppression and differentiation during DEX-dependent chondrogenesis. SCRG1 may be of utility in gene-mediated cartilage tissue engineering.
Ochi
Kensuke
K
Cartilage Biology and Orthopaedics Branch, National Institute of Arthritis, and Musculoskeletal and Skin Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892-8022, USA.
Derfoul
Assia
A
Tuan
Rocky S
RS
D000368:Aged; D000369:Aged, 80 and over; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001854:Bone Marrow Cells / Q000502:physiology; D002358:Cartilage, Articular / Q000187:drug effects / Q000254:growth & development*; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D020219:Chondrogenesis / Q000235:genetics*; D003907:Dexamethasone / Q000494:pharmacology*; D005269:Femur; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007719:Knee Joint; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D010641:Phenotype; D011965:Receptors, Glucocorticoid / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D000893:Anti-Inflammatory Agents; D009419:Nerve Tissue Proteins; D011965:Receptors, Glucocorticoid; C510821:SCRG1 protein, human; D003907:Dexamethasone