Dual parameter flow cytometry, measuring DNA and nuclear protein of individual cell nuclei simultaneously, makes it possible to follow cell kinetic perturbations in six distinct compartments of the cell cycle following chemotherapy in vivo. Human ovarian cancer xenografts in nude mice from a primary and recurrent tumor of the same patient were studied. The response to intraperitoneal application of cis-platinum was assessed by tumor volume measurements, changes in labeling indices by autoradiography, and dual parameter flow cytometry. Sequential tissue samples were taken from each tumor using
.-The cytostatic and cytotoxic effects of chemotherapeutic agents usually depend on a selective toxicity to proliferating cells. The majority of these agents interfere at one level or another with the synthesis of DNA (deoxyribonucleic acid). This understanding gave the impetus in our laboratory to study cell kinetics over the past 15 years. In 1970, Averette et al. (2) first presented data studying in vivo cell kinetic characteristics of human genital tissues, determining the labeling index with autoradiography. He later applied this method to assess the effects of cell cycle phase specific drugs, such as methotrexate and vincristine, on cell cycle perturbations, measuring labeling indices (LI) and mitotic indices (MI) with repeated biopsies during chemotherapy (3). Continuous methotrexate infusion, which blocks cycling cells in S-phase, resulted in a n increase in LI, while vincristine, which blocks cells in mitosis, resulted in a n increase i n MI. The disadvantages of these methods are that LI determinations have to be done on fresh biopsy material, and they are time consuming and costly. Since solid tumors have only a small percentage of cells in S-phase and M-phase, determining the LI and MI assesses only a small fraction of tumor cells to observe cell kinetic perturbations following chemotherapy.fine needle aspirations as a microbiopsy method. Pretherapy samples were compared to multiple specimens collected up to 18 days after therapy. Morphologic changes of each specimen were also assessed. Cis-platinum affects malignant cells in the G~R , S, G2*, and Gzn compartments with various intensities and different time frames, depending on the drug sensitivity of each individual tumor.Key terms: Multiparameter flow cytometry, nude mouse xenograft, cis-platinum, in vivo chemotherapy effect, fine needle aspiration Since then, flow cytometry (FCM) has become a powerful tool for the quantitative analysis of cell cycle parameters by measuring nuclear DNA content of individual cells at rates approaching 1,000 cells per min (1,14). Resulting DNA histograms identify the relative proportions of cells in GI, S-, and GzM-phases. With the aid of computer assisted data analysis, chemotherapy related cell cycle perturbations can be quantitated on serial samples with relative ease and speed (7,12). We recently published our data on the in vivo effect of chemotherapeutic agents on gynecologic malignancies in patients and nude mouse xenogra...