Morphological changes of mesenchymal stem cells by cyclic stretch

Bone marrow mesenchymal stem cells (MSCs) are capable of self-renewal and can differentiate into multiple non-hematopoietic cell lineages such as smooth muscle cells (SMCs). Mechanical stimulations are critical to morphological changes, development, regeneration, and pathology of mesenchymal tissues. The type of mechanical stimulation applied on the cells is important for the induced cell response and function. To study effects of mechanical load on morphology of stem cells, cyclic strain is applied on cultured cells by use of a designed stretch device capable of operation inside an incubator. Effects of mechanical loading on MSCs morphology are quantified using image processing methods. The tests are performed for 5-15% load amplitudes with 1Hz frequency and 1-8 hour durations. Fractal and topological parameters of cellular images before and after tests are calculated by development of an image processing code. Results demonstrate statistically significant changes in cell morphology and topology due to mechanical stretch. By elevation of load amplitude, fractal dimension decreases and orientation angle increases due to alignment of cells. It is concluded that tensile loading of MSCs influences cell morphology and alignment a mechanism for functional adaptation, structural regulation and differentiation.