Widespread intraspecies cross-contamination of human tumor cell lines arising at source

We present a panoptic survey of cell line cross-contamination (CLCC) among original stocks of human cell lines, investigated using molecular genetic m ethods. The survey comprised 252 consecutive human cell lines, almost exclu sively tumor-derived, submitted by their originators to the DSMZ and 5 addi tional cell repositories (CRs), using a combination of DNA profiling (4-loc us minisatellite and multilocus microsatellite probes) and molecular cytoge netics, exploiting an interactive database (http://www.dsmz.del). Widesprea d high levels of cross-contaminants (CCs) were uncovered, affecting 45 cell lines (18%) supplied by 27 of 93 originators (29%). Unlike previous report s, most CCs (42/45) occurred intraspecies, a discrepancy attributable to im proved detection of the more insidious intraspecies CCs afforded by molecul ar methods. The most prolific CCs were classic tumor cell lines, the number s of CCs they caused being as follows: HeLa (n = 11), T-24 (n = 4), SK-HEP- 1 (n = 4), U-937 (n = 4) and HT-29 (n = 3). All 5 supposed instances of spo ntaneous immortalization of normal cells were spurious, due to CLCC, includ ing ECV304, the most cited human endothelial cell line. Although high, our figure for CCs at the source sets a lower limit only as (i) many older tumo r cell lines were unavailable for comparison and (ii) circulating cell line s are often obtained indirectly, rather than via originators or CRs. The mi sidentified cell lines reported here have already been unwittingly used in several hundreds of potentially misleading reports, including use as inappr opriate tumor models and subclones masquerading as independent replicates. We believe these findings indicate a grave and chronic problem demanding ra dical measures, to include extra controls over cell line authentication, pr ovenance and availability. Int. J. Cancer 83:555-563, 1999. (C) 1999 Wiley- Liss, Inc.