Biophysical interactions of human mesenchymal stem cells and porous silicon
nanoneedles
SW Crowder1,2, CS Hansel1, C Chiappini1,2, MM Stevens1,2,3
1
Department of Materials, 2Department of Bioengineering, and 3Institute of Biomedical
Engineering, Imperial College London, London, UK
Abstract: Human bone marrow-derived mesenchymal stem cells (hMSCs) are a promising
cell source for tissue engineering and regenerative medicine. hMSCs exhibit a particular
sensitivity to the biophysical environment with which they interact, and altering the
physicochemical properties of synthetic culture substrates has allowed for elucidation of
processes that regulate hMSC biology. Recently, the Stevens Group has developed highaspect ratio, porous silicon nanoneedles (nNs) for in vitro and in vivo manipulation of cell
behaviour. Interestingly, the nNs penetrate the cell membrane but do not damage the
nucleus, instead stimulating nuclear condensation (shrinking); however, the mechanisms by
which the needles generate changes in the nucleus have not been explored.
In the present study, we have investigated the biophysical interactions between
hMSCs and nNs, including changes in the organization of the actin cytoskeleton and
expression of key components of the nuclear envelope that occur in response to the presence
of nNs. Furthermore, we have measured the pattern of methylated histones in the DNA of
hMSCs on nN and are working to correlate these data with functional capacity for
differentiation. Our data indicate that the presence of nN affects the organization of the actin
cytoskeleton and the morphology of the nucleus, and these effects are thought to be mediated
through changing expression patterns of focal adhesion and nuclear envelope genes. This
ongoing work employs a novel cell culture platform for investigating and elucidating
fundamental processes in stem cell biology, and will be used to enhance the differentiation
capacity of hMSCs for tissue engineering applications.