Objective

The aim of this study was to investigate PDGF release in the peripheral circulation following trauma and to correlate it with the numbers of MSCs in iliac crest bone marrow (BM) aspirate.

Background and objectives

Fracture healing represents a physiological process regulated by a variety of signalling molecules, growth factors and osteogenic progenitor cells. Bone healing following trauma is associated with increased serum concentrations of several pro-inflammatory and angiogenic growth factors1. Platelet-derived growth factor (PDGF) has been shown to stimulate mesenchymal stem cell (MSC) proliferation in vitro. However, the in vivo relationship between the levels of PDGF and the numbers of MSCs in humans has not yet been explored. The aim of this study was to investigate PDGF release in the peripheral circulation following trauma and to correlate it with the numbers of MSCs in iliac crest bone marrow (BM) aspirate and in peripheral blood.

Background: It has been previously shown that in elderly patients with osteoporosis the Mesenchymal Stem Cell (MSC) growth rate and osteogenic potential is decreased. The aim of this study was to elucidate the effect of BMP-2, BMP-7, PTH and PDGF on MSC’s capacity to proliferate and differentiate.

Methods: Cancellous bone samples were obtained from 10 patients (mean age 76 (70–84), (4 males)) suffering from lower extremity fractures and osteoporosis. Mes-enchymal Stem Cells (MSCs) were isolated by enzymatic digestion. Cells were cultured till passage 3 (P3). Functional assays on proliferation and osteogenic differentiation were performed under the influence of a wide range of BMP-2, BMP-7, PTH and PDGF concentrations. Proliferation was assessed using CFU-F and XTT assays. Osteogenic differentiation was assessed by alkaline phosphatase activity and total calcium production.

Results: MSC proliferation was found upregulated by medium supplementation with BMP-7 and PDGF. The highest proliferation rate increase was achieved with 100 ng/ml of BMP-7. BMP-2 and PTH did not affect MSC proliferation. All four molecules upregulated ALP activity and calcium production by growing osteoblasts. A dose dependant effect was noted. BMP-2 and BMP-7 in their highest studied concentration (100 ng/ml) produced a ~ three-fold increase on osteogenic potential of MSCs.

Conclusion: This study indicates that BMP-7 and BMP-2 have favourable effect on osteogenic differentiation of MSCs. However, BMP-7 could be more advantageous as it enhances both proliferation and osteogenic differentiation of MSCs derived from elderly osteoporotic bone.