Article
Dose dependent effect of GDF-5 on proliferation and ostogenic differentiation of human mesenchymal stromal cells
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Published: | October 18, 2011 |
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Questionnaire: Growth factors are proteins that serve as signalling agents for cells and function as a part of a cellular communication network. There are numbers of potential clinical applications for growth factors in the enhancement of bone repair, including acceleration of fracture-healing, treatment of established non-union or enhancement of primary spinal fusion. Bone morphogenetic proteins (BMPs) - with some of them also being referred to as growth-and-differentiation-factors (GDFs) - belong to the transforming growth factor-b (TGF-b) superfamily which have proven to be potent agents to induce bone formation. Currently, the range of growth factors being available for clinical bone regeneration applications is limited. Up to now for specific indications only BMP-2, BMP-7, and GDF-5 (BMP-14) are in clinical use.
The aim of the present study was to investigate the dose dependent effects of GDF-5 on proliferation and osteogenic differentiation of human mesenchymal stromal cells (hMSCs).
Methods: HMSCs of 4 healthy donors were pooled and cultured with different amounts of GDF-5 for up to 28 days with and without osteogenic supplements (i.e. dexamethasone, beta-glycerophosphate, ascorbic acid, vitamin D3). Proliferation was assessed by total DNA quantification. For evaluation of osteogenic differentiation cell-specific alkaline phosphatase (ALP) activity as well as calcium content was determined. Additionally, osteogenic differentiation was proofed qualitatively by fluorescent ALP staining and by Runx-2, ALP, and BSP-2 marker gene expression analysis using quantitative real-time PCR.
Results and Conclusions: Compared to the control (cell cultures not conditioned with growth factor) a significantly (p<0.05) higher increase in cell number and specific ALP-activity could be observed for osteogenically stimulated cells that were cultured with 10, 50 and 200 ng/ml GDF-5, respectively. After 28 days of cultivation the expression of the osteogenic transcription factor Runx-2 was higher in non-stimulated cells treated with 100 ng/ml GDF-5 compared to controls. Additionally, GDF-5 significantly enhanced the expression of BSP-2 gene in osteogenically as well as in non-stimulated hMSCs and was even more effective than BMP-2.
We conclude that GDF-5 promotes osteogenic differentiation of hMSCs as shown by stimulatory effects on the expression levels of crucial bone differentiation markers. These findings make GDF-5 an attractive growth factor for clinical bone regeneration applications.