Mechanical properties of stem cells from different sources during vascular smooth muscle cell differentiation.

Vascular smooth muscle cells (VSMCs) play an important role in regulating blood flow and pressure by contracting and relaxing in response to a variety of mechanical stimuli. A fully differentiated and functional VSMC should have both the ability to contract and relax in response to environmental stimuli. In addition, it should have the proper mechanical properties to sustain the mechanically active vascular environment. Stem cells can differentiate towards VSMC lineages and so could be used as a potential treatment for vascular repair. However, few studies have assessed the time it takes for stems cells to acquire similar mechanical property to native VSMCs during differentiation. In our study, changes in the mechanical properties of differentiating bone marrow and adipose-derived stem cells were determined by using atomic force microscopy indentation. Overall, bone marrow derived stem cells achieved higher elastic moduli than adipose tissue derived stem cell during differentiation. Immunofluorescence shows that both stem cell types have increasing VSMC-specific markers over differentiation. While adipose-derived stem cells were softer, they expressed slightly higher αSMA than the bone marrow cells as investigated by RT-PCR. Further investigations are required to better determine the appropriate mechanical environment for vascular smooth muscle differentiation.