, Beatriz Betancourt, Somen Baidya, Ahmed M. Hassan, Waleed Al-Shaikhli,
In living systems, it is frequently stated that form follows function by virtue of evolutionary pressures on organism development, but in the study of how functions emerge at the cellular level, function often follows form. We study this chicken versus egg problem of emergent structure-property relationships in living systems in the context of primary human bone marrow stromal cells cultured in a variety of microenvironments that have been shown to cause distinct patterns of cell function and differentiation. Following cell culture in diverse microenvironments, we introduce a family of metrics to characterize the form of the cell populations that emerge. In particular, we consider measures of form that we expect to have direct significance for cell function, signaling and metabolic activity. These metrics include dimensionality, polarizability and capacitance. Dimensionality was assessed by an intrinsic measure of cell shape obtained from the polarizability tensor. This tensor defines ellipsoids for arbitrary cell shapes and the thinnest dimension of these ellipsoids, P1, defines a reference minimal scale for cells cultured in a 3D microenvironment. Polarizability governs the electric field generated by a cell, and determines the cells ability to detect electric fields. Capacitance controls the shape dependence of the rate at which diffusing molecules contact the surface of the cell, and this has great significance for inter-cellular signaling. These results invite new approaches for designing scaffolds which explicitly direct cell dimensionality, polarizability and capacitance to guide the emergence of new cell functions derived from the acquired form.
IEEE Transactions on Biomedical Engineering
stem cells, differentiation, tissue scaffold, cell shape, shape measures, capacity, polarizability tensor