BMP3 Alone and Together with TGF-β Promote the Differentiation of Human Mesenchymal Stem Cells into a Nucleus Pulposus-Like Phenotype.

Xiaopeng Zhou,Qixin Chen,Yujie Zhang,Hao Li,Yiqing Tao,Chengzhen Liang

doi:10.3390/ijms160920344

Xiaopeng Zhou, Qixin Chen + Show 4 more

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https://doi.org/10.3390/ijms160920344

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Abstract

Human mesenchymal stem cells (MSCs) have the potential to differentiate into nucleus pulposus (NP)-like cells under specific stimulatory conditions. Thus far, the effects of bone morphogenetic protein 3 (BMP3) and the cocktail effects of BMP3 and transforming growth factor (TGF)-β on MSC proliferation and differentiation remain obscure. Therefore, this study was designed to clarify these unknowns. MSCs were cultured with various gradients of BMP3 and BMP3/TGF-β, and compared with cultures in basal and TGF-β media. Cell proliferation, glycosaminoglycan (GAG) content, gene expression, and signaling proteins were measured to assess the effects of BMP3 and BMP3/TGF-β on MSCs. Cell number and GAG content increased upon the addition of BMP3 in a dose-dependent manner. The expression of COL2A1, ACAN, SOX9, and KRT19 increased following induction with BMP3 and TGF-β, in contrast to that of COL1A1, ALP, OPN, and COMP. Smad3 phosphorylation was upregulated by BMP3 and TGF-β, but BMP3 did not affect the phosphorylation of extracellular-signal regulated kinase (ERK) 1/2 or c-Jun N-terminal kinase (JNK). Our results reveal that BMP3 enhances MSC proliferation and differentiation into NP-like cells, as indicated by increased cell numbers and specific gene expressions, and may also cooperate with TGF-β induced positive effects. These actions are likely related to the activation of TGF-β signaling pathway.

Highlights

The intervertebral disc (IVD) is composed of a highly hydrophilic central nucleus pulposus (NP)surrounded by the annulus fibrosus (AF) and cartilaginous endplate [1]
transforming growth factor (TGF)-β (1 BT) or to 10 ng/mL bone morphogenetic protein 3 (BMP3) and 10 ng/mL TGF-β (10 BT) showed a similar proliferation level to those treated with TGF-β alone (T), indicating that the concentrations of BMP3 used were not sufficient for increasing cell proliferation
Western blotting was performed to analyze the expression of Smad3, pho-Smad3, ERK1/2, pho-ERK1/2, Jun N-terminal kinase (JNK), and pho-JNK proteins, which are involved in TGF-β, extracellular-signal regulated kinase (ERK), and JNK signaling pathways

Summary

Introduction

The intervertebral disc (IVD) is composed of a highly hydrophilic central nucleus pulposus (NP)surrounded by the annulus fibrosus (AF) and cartilaginous endplate [1]. Degeneration of IVD occurs predominantly in the NP, which is abundant in proteoglycan, aggrecan, and type II collagen. Studies have revealed two main cell types within the NP, small chondrocyte-like cells and large vacuolated cells derived from the notochord [2]. The disappearance of NP-like cells due to various reasons leads to a loss of extracellular matrix proteins, thereby influencing the structural integrity of the NP, and initiating the IVD degeneration [3]. Cell-based tissue engineering is being widely evaluated to repair the degenerating IVD. Human mesenchymal stem cells (MSCs) are adult tissue-derived progenitor cells with the ability to differentiate into various cell types [4]. Several reports have demonstrated that MSCs can be guided into the NP-like phenotype under specific culture conditions, including the presence of growth factors, three-dimensional scaffold, and hypoxia among others [5,6]

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