Classical and molecular cytogenetic analysis

False and mycoplasma-contaminated leukemia-lymphoma cell lines: time for a reappraisal

Leukemia-lymphoma cell lines are important research tools in a variety of fields. To represent adequate model systems it is of utmost importance that cell lines faithfully model the primary tumor material and are not cross-contaminated with unrelated cell material (or contaminated with mycoplasma). As it has been previously reported that cross-contaminated cell lines represent a significant problem, it is of interest to know whether any improvement in the prevalence of such "false cell lines" had occurred since we called the alert in 1999. A retrospective review of our data archives covered 848 cell lines received from 1990 to 2014 from 290 laboratories in 23 countries spanning the spectrum of leukemia-lymphoma entities. Two variables were considered: authenticity and freedom from mycoplasma infection. Regarding provenance, we separately considered primary sources (original investigators having established the cell lines or reference repositories) and secondary sources. The percentages of mycoplasma-contaminated cell lines decreased significantly over the 25-year timespan. Among primary sourced material: mycoplasma-contamination fell from 23% to 0%; among secondary sourced: from 48% to 21%. The corresponding figures for cross-contamination declined from 15% to 6%, while among material obtained from secondary sources prevalence remained remarkably high, throughout the time periods at 14-18%. Taken together, our data indicate that using non-authenticated cell lines from secondary sources carries a risk of about 1:6 for obtaining a false cell line. The use of authentic leukemia-lymphoma cell lines holds important translational value for their model character and the reproducibility of the laboratory data in the clinical arena.

Assessing the quality of donor cells: karyotyping methods

Somatic cell nuclear transfer (SCNT) has a low success rate that rarely exceeds 5 %. Moreover, SCNT requires highly technical skills and may be influenced by the biological material used (oocyte and donor cell quality). Hence, it is crucial to check the normality of the donor cell's karyotype. Numerical and structural chromosome abnormalities are detected by cytogenetic analysis at minimum using G-banding to identify the chromosomes. Here, we describe the classical protocols that are needed to perform complete cytogenetic analyses, i.e., G-banding to identify chromosome aberrations, followed by Fluorescent In Situ Hybridization (FISH) of specific probes for a more sensitive detection and precise identification of the rearrangement.