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Effect of IGF‐I in the Chondrogenesis of Bone Marrow Mesenchymal Stem Cells in the Presence or Absence of TGF‐β Signaling
Author(s) -
Longobardi Lara,
O'Rear Lynda,
Aakula Srikanth,
Johnstone Brian,
Shimer Kimberly,
Chytil Anna,
Horton William A,
Moses Harold L,
Spagnoli Anna
Publication year - 2006
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.051213
Subject(s) - chondrogenesis , mesenchymal stem cell , microbiology and biotechnology , chemistry , cellular differentiation , transforming growth factor beta , chondrocyte , stem cell , biology , transforming growth factor , cartilage , anatomy , biochemistry , gene
Abstract A novel role for IGF‐I in MSC chondrogenesis was determined. IGF‐I effects were evaluated in the presence or absence of TGF‐β signaling by conditionally inactivating the TGF‐β type II receptor. We found that IGF‐I had potent chondroinductive actions on MSCs. IGF‐I effects were independent from and additive to TGF‐β. Introduction: Mesenchymal stem cells (MSCs) can be isolated from adult bone marrow (BM), expanded, and differentiated into several cell types, including chondrocytes. The role of IGF‐I in the chondrogenic potential of MSCs is poorly understood. TGF‐β induces MSC chondrogenic differentiation, although its actions are not well defined. The aim of our study was to define the biological role of IGF‐I on proliferation, chondrogenic condensation, apoptosis, and differentiation of MSCs into chondrocytes, alone or in combination with TGF‐β and in the presence or absence of TGF‐β signaling. Materials and Methods: Mononuclear adherent stem cells were isolated from mouse BM. Chondrogenic differentiation was induced by culturing high‐density MSC pellets in serum‐ and insulin‐free defined medium up to 7 days, with or without IGF‐I and/or TGF‐β. We measured thymidine incorporation and stained 2‐day‐old pellets with TUNEL, cleaved caspase‐3, peanut‐agglutinin, and N‐cadherin. Seven‐day‐old pellets were measured in size, stained for proteoglycan synthesis, and analyzed for the expression of collagen II and Sox‐9 by quantitative real time PCR. We obtained MSCs from mice in which green fluorescent protein (GFP) was under the Collagen2 promoter and determined GFP expression by confocal microscopy. We conditionally inactivated the TGF‐β type II receptor (TβRII) in MSCs using a cre‐lox system, generating TβRII knockout MSCs (RIIKO‐MSCs). Results and Conclusions: IGF‐I modulated MSC chondrogenesis by stimulating proliferation, regulating cell apoptosis, and inducing expression of chondrocyte markers. IGF‐I chondroinductive actions were equally potent to TGF‐β1, and the two growth factors had additive effects. Using RIIKO‐MSCs, we showed that IGF‐I chondrogenic actions are independent from the TGF‐β signaling. We found that the extracellular signal‐related kinase 1/2 mitogen‐activated protein kinase (Erk1/2 MAPK) pathway mediated the TGF‐β1 mitogenic response and in part the IGF‐I proliferative action. Our data, by showing the role of IGF‐I and TGF‐β1 in the critical steps of MSC chondrogenesis, provide critical information to optimize the therapeutic use of MSCs in cartilage disorders.