Semiautomation of preparation of fixed paraffin-embedded tissue for DNA analysis.

: The usual manual preparation of single-cell suspensions from fixed paraffin-embedded tissue sections for flow cytometric (FCM) DNA ploidy analysis is a time-consuming, labor-intensive technique that requires 70 minutes to deparaffinize and rehydrate 50 microns sections as the initial step. Manual deparaffinization was compared with two semiautomated methods using an automatic slide stainer with either a 70-minute or 35-minute schedule. Samples from 6 normal tissues and 21 tumors (13 diploid and 8 aneuploid) were prepared using all three methods and analyzed by FCM. The mean cell counts in all samples were over 10(6). The DNA indices for the three samples prepared from a given tissue showed no significant differences. Using the 70-minute automation schedule, no aneuploid peaks were lost, and the ratio of G0G1 normal cells to aneuploid tumor cells was maintained. The automation of deparaffinization can thus provide a significant reduction in the labor need to produce single-cell suspensions for FCM; it can be especially helpful when handling large numbers of tumors. At the same time, the automated procedure decreases the exposure to hazardous chemicals and lowers the chance of losing tissue.