REAL-TIME METHOD FOR DETERMINING THE COLONY-FORMING CELL CONTENT OF HUMAN HEMATOPOIETIC-CELL CULTURES

Glucose and lactate metabolic rates were evaluated for cultures of cor d blood (CB) mononuclear cell (MNC), peripheral blood (PB) MNC, and PB CD34(+) cell cultures carried out in spinner flasks and in T-flasks i n both serum-containing and serum-free media. Specific glucose uptake rates (q(gluc), in micromoles per cell per hour) and lactate generatio n rates (q(lac)) correlated with the percentage of colony-forming cell s (CFC) present in the culture for a broad range of culture conditions . Specifically, the time of maximum CFC percentage in each culture coi ncided with the time of maximum q(gluc) and q(lac) in cultures with di fferent seeding densities and cytokine combinations. A two-population model (Q(lac) = alpha[CFC] + beta([TC] - [CFC]), where [TC] is total c ell concentration; Q(lac) is volumetric lactate production rate in mic romoles per milliliter per hour; alpha is q(lac) for an average CFC; a nd beta is q(lac) for an average non-CFC) was developed to describe la ctate production. The model described lactate production well for cult ures carried out in both T-flasks and spinner flasks and inoculated wi th either PB or CB MNC or PB CD34(+) cells. The values for alpha and b eta that were derived from the model varied with both the inoculum den sity and the cytokine combination. However, preliminary results indica te that cultures carried out under the same conditions from different samples with similar initial CD34(+) cell content have similar values for alpha and beta. These findings suggest that it should be possible to use lactate production data to predict the harvest time that corres ponds to the maximum number of CFC in culture. The ability to harvest ex vivo hematopoietic cultures for transplantation when CFC are at a m aximum has the potential to speed the rate at which immunocompromised patients recover. (C) 1997 John Wiley & Sons, Inc.