Laser printing of single cells: statistical analysis, cell viability, and stress

Methods to print patterns of mammalian cells to various substrates with high resolution offer unique possibilities to contribute to a wide range of fields including tissue engineering, cell separation, and functional genomics. This manuscript details experiments demonstrating that BioLP Biological Laser Printing, can be used to rapidly and accurately print patterns of single cells in a noncontact manner. Human osteosarcoma cells were deposited into a biopolymer matrix, and after 6 days of incubation, the printed cells are shown to be 100% viable. Printing low numbers of cells per spot by BioLP is shown to follow a Poisson distribution, indicating that the reproducibility for the number of cells per spot is therefore determined not by the variance in printed volume per drop but by random sampling statistics. Potential cell damage during the laser printing process is also investigated via immunocytochemical studies that demonstrate minimal expression of heat shock proteins by printed cells. Overall, we find that BioLP is able to print patterns of osteosarcoma cells with high viability, little to no heat or shear damage to the cells, and at the ultimate single cell resolution.