Cell organelle-based analysis of cell chirality.

The maintenance of tight endothelial junctions requires the establishment of proper cell polarity, which includes not only the apicobasal and front-rear polarity but also the left-right (L-R) polarity. The cell possesses an intrinsic mechanism of orienting the L-R axis with respect to the other axes, following a left-hand or right-hand rule, termed cell chirality. We have previously reported that endothelial cells exhibit a clockwise or rightward bias on ring-shaped micropatterns. Now we further characterize the chirality of individual endothelial cells on micropatterns by analyzing the L-R positioning of the cell centroid relative to the nucleus-centrosome axis. Our results show that the centroids of endothelial cells preferably polarized towards the right side of the nucleus-centrosome axis. This bias is consistent with cell chirality characterized by other methods. These results suggest that the positioning of cell organelles is intrinsically L-R biased inside individual cells. This L-R bias provides an opportunity for determining cell chirality in situ, even in vivo, without the limitations of using isolated cells in in vitro engineered platforms.