ON THE USE OF SYRIAN-HAMSTER CELL-CULTURES AS TARGETS FOR CARCINOGEN-SCREENING

Syrian hamster embryo (SHE) cells have a reported culture lifespan lim ited to 30 to 40 population doublings (PDs). In contrast, we have obse rved continuous growth of two SHE cell lines without the hallmarks of cellular senescence. Two independent primary isolates (SHE-3, and SHE- 15) have been grown for more than 160 PDs (SHE-3) and 50 PDs (SHE-15), respectively, with weekly subcultures and with no sign of senescence. During this study, we observed that SHE-3 cells ceased to multiply af ter about 30 PDs when grown in a nutritionally-inadequate serum-free m edium, but resumed growth when switched to an adequate medium. The chr omosomal profiles of both SHE cultures revealed a near diploid karyoty pe but not a completely normal karyotype, even at early passages with increasing chromosomal changes with continued culture. In addition, Sy rian hamster chondrocytes were isolated, partially characterized, and their sensitivity to chemically-induced morphological transformation w as compared to that of the standard Syrian hamster embryo (SHE) mixed cell culture. It appears that chondrocytes may be a suitable and more sensitive target for carcinogen-screening in vitro.