Short bouts of mechanical loading are as effective as dexamethasone at inducing matrix production by human bone marrow mesenchymal stem cells

Abstract

Dexamethasone (Dex) is used widely to induce differentiation in human mesenchymal stem cells (hMSCs); however, using a pharmaceutical agent to stimulate hMSC differentiation is not the best choice for engineered tissue transplantation due to potential side-effects. The goal of the present study was to investigate the effects of dynamic compressive loading on differentiation and mineralized matrix production of hMSCs in 3D polyurethane scaffolds, using a loading regimen previously shown to stimulate mineralised matrix production of mature bone cells (MLO-A5). hMSCs were seeded in polyurethane scaffolds and cultured in standard culture media with or without Dex. Cell-seeded scaffolds were compressed at 5% global strain for 2 h on day 9 and then every 5 days in a media-filled sterile chamber. Samples were tested for mRNA expression of alkaline phosphatase (ALP), osteopontin (OPN), collagen type 1 (col 1) and runt-related transcription factor-2 (RUNX-212 h) after the first loading, cell viability by MTS assay and alkaline phosphatase activity at day 12 of culture and cell viability, collagen content by Sirius red and calcium content by alizarin red at day 24 of culture. Neither Dex nor loading had significant effects on cell viability. Collagen content was significantly higher (p<0.01) in the loaded group compared with the non-loaded group in all conditions. There was no difference in ALP activity or the amount of collagen and calcium produced between the non-loaded group supplemented with Dex and the loaded group without Dex. We conclude that dynamic loading has the ability to stimulate osteogenic differentiation of hMSC in the absence of glucocorticoids.

Quantification of fluid shear stress in bone tissue engineering scaffolds with spherical and cubical pore architectures

“…However, our model predicts that under a compressive strain of 5% (1Hz) in 400μm pore-size scaffolds, which has been experimentally shown to achieve enhanced osteogenic differentiation (i.e. higher ALP, osteopontin expression and calcium content) of human bone marrow-derived MSCs (Sittichokechaiwut et al 2010), the resulting WSS would be between 4.12-7.18mPa and thus well within the range to stimulate an osteogenic response. In addition, an in vivo study by Duty et al (2007), it was found that bone tissue formation and mineralisation were enhanced within a porous PLA scaffold (p=71%, d=397µm) under dynamic compression with a compressive strain of 1.8% and frequency of 1Hz.…”

The effect of mechanical loading on osteogenesis of human dental pulp stromal cells in a novel in vitro model

“…5% global strain of compression was applied for bone formation (Sittichockechaiwut et al 2009;Sittichokechaiwut et al 2010). Although, it was proved mechanical stimulation affected the cell behavior in the construct as a whole, few researches looked into a scaffold to find the differences among areas except for some computer models (Lacroix et al 2006;O'Brien et al 2007).…”

“…A bioreactor provides a controllable environment to create a bio-tissue both for systematic scientific research and for potential using in implant and replacement of damaged tissue (Sittichockechaiwut et al 2009;Sittichokechaiwut et al 2010).With regarding to mimicking the dynamics of the in vivo environment, the complexity of mechanical properties in different tissues (e.g. bone, cartilage, tendon and ligament, and cardiovascular tissue) should be considered and distinguished (Huselstein et al 2008).…”

Gene Expression Responses to Mechanical Stimulation of Mesenchymal Stem Cells Seeded on Calcium Phosphate Cement

“…Commonly a gel based scaffold or tissue culture plastic has been used as the substrate on which cells were mechanically loaded, and the strain employed has been in the range of 2%-20%. 6,[12][13][14][15][16][17][18][19][20] Neither the scaffold nor the strain of this magnitude represents the true environment or magnitude of physiological or pathological loading of bone in humans in vivo. Further, a number of studies in vivo have been carried out in an attempt to overcome these obstacles, but these are limited to animal models and therefore could be associated with differences in responses to loading and mechanisms involved from one species to another.…”