Micropatterning of endothelial cells by guided stimulation with angiogenic factors

Micropatterning technology holds significant promise in the development of micro/nanomedical devices. The precise control of cell position and migration is important in several applications. For example, the optimal design of implantable devices depends on the implant material's micro-and nano-texture, which influences the response of nearby tissue, including the microvessels. Therefore, we were interested in endothelial cell positioning and colonization on specific surface domains in the size range of microvasculature. To this end, endothelial cells were seeded in microfabricated grooves and exposed to vascular endothelial growth factor (VEGF), which plays a key role in the angiogenic response. Patterned silicon wafers with grooves of 50μm width and depth and 150μm groove spacing were used. Each patterned region had two semicircular ports at either end, one of which was used to seed human retinal endothelial cells (HREC) and the other to house VEGF embedded in Matrigel. After 1 week, cells were fixed and analyzed by laser scanning cytometry (LSC). Our results shows that we can control HREC seeding and positioning in surface grooves and that the speed of colonization of the grooves can be manipulated by local VEGF application. We were able to quantify this effect, showing that HREC relocate inside the grooves twice as fast in response to VEGF stimulation, compared to control conditions, at a speed of 3.14±0.01 and 1.55±0.01μm/min, respectively. Our approach could be used towards the fabrication of "designer" substrates or devices that not only allow patterned cell growth, but also permit dynamic cell repositioning.