Sister chromatid exchange in chronic ethylene oxide-exposed primates: unexpected effects of in vitro culture duration, incubation temperature, and serum supplementation.
Kelsey-KT; Wiencke-JK; Eisen-EA; Lynch-DW; Lewis-TR; Little-JB
Cancer Res 1989 Apr; 49(7):1727-1731
Experiments were performed to test whether high sister chromatid exchange (SCE) frequency cells (HFCs), like other highly damaged cells acutely exposed to alkylating agents, proliferate more slowly in-vitro than unexposed cells and thus may be detected in greater numbers when cells are allowed to grow for additional times before cytogenetic analysis is performed. The study was initiated in 1979 with 36 adult male cynomolgus-monkeys. Earlier work indicated that elevations of SCE persisted for 6 years after the cessation of ethylene-oxide (75218) (EtO) exposure in cynomolgus-monkeys chronically exposed to EtO. The elevation in mean SCE was entirely attributable to a subpopulation of HFCs. The current study indicated that the detection of persistent HFCs is dependent on the conditions of cell growth. EtO exposure increases the replication indices of lymphocytes from the exposed animals when these cells are examined at early cytogenetic harvest times. The mean SCE frequency is affected by culturing lymphocytes in differing serum supplements, changing cytogenetic harvest times, and altering in-vitro incubation temperature, thus influencing the detection of HFCs. The 5- bromodeoxyuridine concentration used for differential staining of sister chromatids had no effect on the frequency of EtO induced HFCs. The authors conclude that the detection of persistent alkylation induced chromosomal changes observed long after the in- vivo chronic exposure had stopped was highly dependent on factors which affect cell growth. In-vitro culture conditions which preferentially detect slowly proliferating HFCs could be used to improve the sensitivity of the sister chromatid exchange assay as an indicator of chromosomal damage. Cell cycle progression might also be a potential epidemiological confounder in chronic EtO exposure situations.
NIOSH-Author; Inhalation-studies; Laboratory-animals; Genotoxic-effects; Long-term-study; In-vitro-studies; Cell-cultures; Nucleic-acids; Cell-damage; Toxic-gases; Alkylating-agents