Micropattern size-dependent endothelial differentiation from a human induced pluripotent stem cell line.

The multifaceted extracellular milieu presents biochemical and biophysical stimuli that influence stem cell differentiation. Two-dimensional (2D) micropatterned substrates allow the presentation of these cues in spatially defined geometries that have been demonstrated to guide stem cell fate decisions. Leveraging stem cells to reconstruct microvasculature, made up of an inner lining of endothelial cells (ECs) supported by pericytes, is critical to tissue-engineering advances; thus, methods to improve endothelial differentiation efficiency are vital to these efforts. In this study, we examine the hypothesis that the diameter of micropatterned islands influences endothelial differentiation from human induced pluripotent stem cells (hiPSCs). Comparing island diameters of 80, 140, 225 and 500 µm, we found that co-cultures of control ECs and pericytes did not yield variable ratios of cell types; however, when hiPSCs were differentiated toward a bicellular population of ECs and pericytes on these varying micropattern feature sizes, we found that smaller islands promoted EC differentiation efficiency, yielding a derived population composed of 70% ECs, which exhibited a greater sprouting propensity. Differentiation on the largest feature size exhibited a smaller EC yield, similar to that on non-patterned substrates. Taken together, these data demonstrate that micropatterned islands of varying diameters can be used to modulate EC differentiation efficiency.