Osteogenesis of Mesenchymal Stem Cells by Nanoscale Mechanotransduction

It Is likely that mesenchymal stem cells will find use in many autologous regenerative therapies. However, our ability to control cell stem growth and differentiation is presently limited, and this is a major hurdle to the clinical use of these multlpotent cells especially when considering the desire not to use soluble factors or complex media formulations in culture. Also, the large number of cells required to be clinically useful is currently a hurdle to using materials-based (stiffness, chemistry, nanotopography, etc.) culture substrates. Here we give a first demonstration of using nanoscale sinusoidal mechanotransductive protocols (10-14 nm displacements at 1 kHz frequency), nanokIcking, to promote osteoblastogenesis In human mesenchymal stem cell cultures. On the basis of application of the reverse piezo effect, we use interferometry to develop the optimal stem cell stimulation conditions, allowing delivery of nanoscale cues across the entire surface of the Petri dishes used. A combination of immundluorescence, PCR, and microarray has then been used to demonstrate osteoblastogenesis, and the arrays implicate RhoA as central to osteoblastic differentiation in agreement with materials-based strategies. We validate this with pharmacological inhibition of RhoA klnase. It Is easy to envisage such stimulation protocols being up-scaled to form largescale osteoblast bloreactors as standard cell culture plates and incubators are used In the