Image cytometry for analyzing regional distribution of cells inside human neurospheres

An image cytometry algorithm was developed to identify and quantify immunologically labeled cells in cultured human neurospheres. Image cytometry revealed new findings in terms of the localization of specific types of neural cells and the regional fluctuation of cell density in neurospheres. The distributions of total cell density exhibited similar profiles along the radial distance from the periphery of a neurosphere, irrespective of neurosphere sizes examined; approximately 1.0×106 cell/mm3 in the vicinity of the periphery and 6.0×105 cell/mm3 in an inner region of 50–180 μm. In addition, BrdU-positive (proliferating) cells were present at ratios of 53–64% across the entire region of the neurospheres, whereas BrdU-negative and β III tubulin-positive cells (postmitotic neurons) were minorities in the neurospheres.