Runx2 Overexpression Enhances Osteoblastic Differentiation and Mineralization in Adipose - Derived Stem Cells in vitro and in vivo

Abstract

Like bone marrow stromal cells, adipose tissue-derived stem cells (ADSCs) possess multilineage potential, a capacity for self-renewal and long-term viability. To confirm whether ADSCs represent a promising source of cells for gene-enhanced bone tissue-engineering, the osteogenic potential of ADSCs under the control of certain osteoinductive genes has been evaluated. Runx2, a transcription factor at the downstream end of bone morphogenetic protein (BMP) signaling pathways, is essential for osteoblast differentiation and bone formation. In this study we used adenovirus vector to deliver Runx2 to ADSCs and then examined the enhancement of osteogenic activity. Overexpression of Runx2 inhibited adipogenesis, as demonstrated by suppression of LPL and PPARgamma expression at the mRNA level and reduced lipid droplet formation. Moreover, ADSCs transduced with Ad-Runx2 underwent rapid and marked osteoblast differentiation as determined by osteoblastic gene expression, alkaline phosphatase activity and mineral deposition. Additionally, histological examination revealed that implantation of Runx2 modified ADSCs could induce mineral deposition and bone-like tissue formation in vivo. These results confirmed, firstly, the ability of Runx2 to promote osteogenesis and cell differentiation and, secondly, the competence of ADSCs as target cells for bone tissue engineering. Our work demonstrates a potential new approach for bone repair using Runx2-modified ADSCs for bone tissue engineering.

Plasticity of granulosa cells: on the crossroad of stemness and transdifferentiation potential

“…Moreover, it is known that BMPs affect granulosa cell physiology, among other things also GCs proliferation [20,58]. It is an important question why GCs are so favorable for osteogenic differentiation and it was postulated that this may be related to RUNX2 transcriptional factor, fundamental for osteogenic differentiation [38,86] and up-regulated in the process of GCs luteinization [60].…”

Osteogenic potency of stem cell-based genetic engineering targeting Wnt3a and Wnt9a

“…Genetically-engineered pluripotent mesenchymal cells expressing transcription factor genes such as Runx2 and Osx [5][6][7][8], and growth factor genes such as BMP-2, -4 and -7 [3,4], showed an increase in their osteogenic activity, thus facilitating both in vitro and in vivo new bone formation. In addition to these osteogenic factors, Wnt signaling has recently been shown to induce in vitro mesenchymal cell proliferation and differentiation [25,26], and to accelerate in vivo bone regeneration [27][28][29].…”

“…For example, overexpression of bone morphogenetic protein-2 (BMP-2) in mesenchymal stem cells has been reported to increase new bone formation in bone defects [4]. In addition, genetic engineering of a number of other growth factor genes, such as BMP-4 and -7 [3], and of transcription factors, such as runt-related transcription factor 2 (Runx2) and osterix (Osx) [5][6][7][8], have also been shown to induce osteoblast differentiation of progenitor cells.…”

Skeletal and Adipose Tissue Engineering with Adipose-Derived Stromal Cells

“…Non-integrating strategies such as liposome based particles and electroporation transiently transfect the cells and have a decreased immune response, but are not as efficient and have variable expression. Zhang et al (2006) used an adenovirus vector to overexpress Runx-2 in mouse adiposederived stromal cells to increase osteogenesis in vitro and in vivo by implanting seeded scaffolds on the back of nude mice. Several strategies have used BMP-2 gene therapy to promote bone healing and osteogenic differentiation.…”