Paper BM-TuP6
Mapping Smooth Muscle Cell Contractile State Regulated by Contractile Proteins using a Novel BioMEMS Moire Mapping Sensor

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Abnormal vascular smooth muscle cell contractility plays an important role in the pathogenesis of hypertension, blood vessel spasm, and atherosclerosis. This paper presents the mapping of smooth muscle cell contractility using a novel optical moiré method. We utilized coherent laser beams to illuminate periodic polymeric substrates where isolated cells were cultured. The diffraction phenomena of coherent laser beams through the polymeric periodic substrates where living cells were cultured introduces moiré patterns and can be used to real-time mapping the cell-substrate traction forces. The PDMS micropillar arrays were embedded between large sidewalls for cell guidance. A polycarbonate flow perfusion chamber is sealed under the chip. The same chip with imbedded pillars with aspect ratio of 1:3 was mounted on a rotational stage parallel to the first substrate. Diffraction moiré patterns can be generated by illuminating coherent beam via two parallel grating lines or grids. The grating lines served as reference gratings for diffraction moiré pattern generation in (0,1,0) or (1,0,0) direction whereas two-dimensional moiré fringes can be formed via two paralleled imbedded pillars. Therefore, contraction of the vascular smooth muscle cells can be real time “magnified” and “mapped” through moiré pattern evolutions. For contractility mapping of vascular smooth muscle cells, we considered the cell total area, cell length and width. On the other hand, we measured the distortion area of the moiré patterns, moiré pattern length and width. In the experiment, these two factors were shown to be consistent. Further, vascular smooth muscle cells were cultured on substrates with serum media to develop focal adhesion, and then the cells were relaxed on serum free media for another 48 hours followed by treating SMCs with contractile agonist lysophosphatidic Acid. We found that the area of the distorted moiré patterns produced on two overlapped periodic substrates were inversely correlated with the distortion of the moiré patterns, thereby indicating that the contraction of vascular smooth muscle cells were inversely correlated with the initial spreading developed in serum. We anticipate that this method will increasingly provide more applications and cell biological insights in vascular cell contraction mechanism study.