Retinal stem cells (RSCs) are promising candidates for patient-derived cell therapy to repair damage to the eye; however, RSCs are rare in retinal samples and lack validated markers, making cell sorting a significant challenge. Here we report a high-resolution deterministic lateral displacement microfluidic device that profiles RSCs in distinct size populations. Only by developing a chip that promotes cell tumbling do we limit cell deformation through apertured channels and thereby increase the size-sorting resolution of the device. We systematically explore a spectrum of microstructures, including optimized notched pillars, to study and then rationally promote cell tumbling. We find that RSCs exhibit larger diameters than most ciliary epithelial cells, an insight into RSC morphology that allows enrichment from biological samples.
Keywords: cell tumbling; ciliary epithelium; deterministic lateral displacement; label-free; microfluidics; retinal stem cells; size-sorting.