A comparison of counterflow centrifugation and unit gravity sedimentation in the separation of mouse bone marrow...

Both Unit Gravity Sedimentation and Counterflow Centrifugation separate cells primarily on the basis of size. However, when performed concurrently on the same normal mouse bone marrow cell suspensions, Unit Gravity Sedimentation was found to be far superior in terms of the recovery of total nucleated cell load and the recovery and enrichment of two classes of functional progenitors: (1) those responsive to the combined stimulus of pregnant mouse uterus extract (PMUE) plus human spleen conditioned medium (HUSPCM), and (2), those responsive to PMUE alone. Neither technique was able to resolve PMUE from PMUE + HUSPCM progenitors. The major limitation of Counterflow Centrifugation for the separation of sub-populations of marrow cells is related to the complexity and range of cell sizes in marrow cell suspensions which lead to significant pellet formation within the elutriator chamber. Furthermore, cells undergoing Counterflow Centrifugation are subjected to forces not encountered in Unit Gravity Sedimentation. Therefore, the basis of the separations is not identical and this is reflected in cell volume distributions of comparable fractions separated by each method.