Regulating chondrogenesis of human mesenchymal stromal cells with a retinoic Acid receptor-Beta inhibitor: differential sensitivity of chondral versus osteochondral development.
OBJECTIVE
Main objective was to investigate whether the synthetic retinoic acid receptor (RAR)-β antagonist LE135 is able to drive in vitro chondrogenesis of human mesenchymal stromal cells (MSCs) or improve differentiation by suppressing hypertrophic chondrocyte development.


METHODS
Chondrogenesis of human bone marrow and adipose tissue-derived MSCs was induced in micromass pellet culture for six weeks. Effects of LE135 alone and in combinatorial treatment with TGF-β on deposition of cartilaginous matrix including collagen type II and glycosaminoglycans, on deposition of non-hyaline cartilage collagens type I and X, and on hypertrophy markers including alkaline phosphatase (ALP), indian hedghehog (IHH) and matrix metalloproteinase (MMP)-13 were assessed.


RESULTS
LE135 was no inducer of chondrogenesis and failed to stimulate deposition of collagen type II and glycosaminoglycans. Moreover, addition of LE135 to TGF-β-treated pellets inhibited cartilaginous matrix deposition and gene expression of COL2A1. In contrast, non-hyaline cartilage collagens were less sensitive to LE135 and hypertrophy markers remained unaffected.


CONCLUSIONS
This demonstrates a differential sensitivity of chondral versus endochondral differentiation pathways to RARβ signaling; however, opposite to the desired direction. The relevance of trans-activating versus trans-repressing RAR signaling, including effects on activator protein (AP)-1 is discussed and implications for overcoming current limits of hMSC chondrogenesis are considered.
Research Center for Experimental Orthopaedics, Heidelberg University Hospital, Heidelberg, Germany.
Solvig
S
Diederichs
Kerstin
K
Zachert
Patric
P
Raiss
Wiltrud
W
Richter
D000293:Adolescent; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000235:genetics; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism; D020219:Chondrogenesis / Q000187:drug effects* / Q000235:genetics; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D003984:Dibenzazepines / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006025:Glycosaminoglycans / Q000378:metabolism; D053823:Hedgehog Proteins / Q000235:genetics; D006801:Humans; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000378:metabolism; D008875:Middle Aged; D018168:Receptors, Retinoic Acid / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D055815:Young Adult
C525809:BMP4 protein, human; D055415:Bone Morphogenetic Protein 4; C499177:COL2A1 protein, human; D024043:Collagen Type II; D003984:Dibenzazepines; D006025:Glycosaminoglycans; D053823:Hedgehog Proteins; C104182:LE 135; D018168:Receptors, Retinoic Acid; D016212:Transforming Growth Factor beta; C082925:retinoic acid receptor beta; D000469:Alkaline Phosphatase; D053509:Matrix Metalloproteinase 13