UC Irvine

Techniques for rapid positive selection, the process of selecting and isolating an individual cell or a distinctive group of cells in the midst of a mixed cellular population, would enhance genetic engineering protocols, cell transformation studies, cell-based screening of random libraries, and many other studies. The goal of this work is to develop and characterize a system for analyzing, sorting, and collecting viable cells from a mixed population while they remain adherent. The attainment of this goal will be based on readily available microfabrication techniques and chemical surface modifications, an optical phenomenon already used in a wide range of cellular micromanipulation techniques, biological measures needed for isolation of single cells, and an understanding of how these elements can work together. This understanding will be built on findings of preliminary research. To make this research possible, dense arrays of cell-sized microstructures, or pallets, and a prototype laser-based release system were constructed. Single pallets within large arrays were selectively released with a single, focused, low energy laser pulse. Cells were cultured on pallet arrays. The system was able to isolate viable, proliferating cells. As a next step, the laser-based release of pallets was characterized with respect to laser and pallet array parameters, including materials used for pallets and for walls between pallets. Progress was made toward characterizing cell health on laser-released pallets with respect to laser and pallet array parameters. Thus, this work demonstrates a technology for sorting rare cells from a heterogeneous population. The benefits of this separation strategy will be greater cell viability, reduction in time and manipulation of selected cells, and a broader set of cell attributes available for cell selection.