Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.
miR-7 and miR-130b Are Differentially Regulated during Mesenchymal Stem Cell Commitment.
Palmer4, Glyn, Danielson2, Laura S., Attur3, Mukundan, Abramson1, Steven B., Hernando2, Eva
Stem cell-based therapies aimed at introducing progenitor cells into cartilage lesions hold great promise for the restoration of damaged articular surfaces following joint injury or osteoarthritis. Key to the generation of a functional repair tissue is the controlled differentiation into the desired phenotype. To this end microRNAs (miRNAs) may be important molecules that regulate this process. By acting as transcriptional repressors, their modulation during differentiation may enable commitment to a specific lineage by suppressing the expression of other lineage markers. In this study we profiled MSCs for miRNA expression following induction into the chondrocyte (C), osteoblast (O) and smooth muscle (SM) lineages.
Human bone marrow-derived Mesenchymal Stem Cells (MSCs) were obtained from NIH, or from the discarded hips of patients undergoing joint replacement surgery. SM differentiation was induced by treating monolayer cultures with 1 mM thromboxane-A2 [DP1] in the presence of 0.25% serum. C differentiation was induced by seeding MSCs in aggregate cultures in the presence of dexamethasone and TGF-b1 (10 ng/ml). O differentiation was induced by treatment of monolayer cultures with dexamethasone, ascorbate and beta-glycerolphosphate. Profiling of miRNAs by microarray (Agilent) or QPCR (SA Biosciences) revealed differential regulation of miR-7 and miR-130b, among 376 probes. Following SM and C differentiation, miR-7 expression was down-regulated up to 6.9-fold and 3-fold respectively. Conversely, during O differentiation, its expression was induced approximately 7-fold. Analysis of theoretical mRNA targets using TargetScan online software (www.targetscan.org) identified conserved sites in several genes associated with chondrocyte and myoblast lineages. Putative chondrogenic targets were found to include COL2A1, IGFR1, and GDF5, while potential smooth muscle modulators included EGFR1, PIK3CD, IRS1/IRS2, KLF4, CNN3 and IGF1R. Following a similar trend to miR-7, miR-130b was down-regulated up to 3.2-fold and 3.1-fold in C and SM differentiation respectively, while O differentiation induced its expression 2-fold. TargetScan analysis identified putative chondrogenic targets, TGF-BRII, Sox5, BMP-2 and IGF1; Potential smooth muscle regulators included ESR1, TGF-BRII, MBLN1, TGFBR1 and IGF2BP1. Together these observations suggest that miR-7 and miR-130b act to negatively regulate myogenic and chondrogenic cell fates via regulation of lineage specific genes.
Our findings suggest that miR-7 and miR-130b, via the targeting of lineage specific molecules, regulate cell fate in adult human MSCs by inhibiting smooth muscle and chondrocyte differentiation, thereby promoting 'default' differentiation into the osteoblast lineage.
[DP1]0.25% FBS 24 hours prior to addition of 1.0mM of the TxA2 chemical analog U46619
To cite this abstract, please use the following information:
Palmer, Glyn, Danielson, Laura S., Attur, Mukundan, Abramson, Steven B., Hernando, Eva; miR-7 and miR-130b Are Differentially Regulated during Mesenchymal Stem Cell Commitment. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1490