A simple and rapid immunological technique for visualising chromosome-mediated gene transfer (CMGT).

A method is described for visualising chromosome-mediated gene transfer (CMGT) by detecting chromosomes labelled with bromodeoxyuridine (BrdU) using a monoclonal antibody to BrdU. In this experiment, the CCRF-CEM T cell line was grown in the presence of BrdU and the labelled chromosomes were isolated and transfected into human embryonic fibroblasts. Uptake and retention of chromosomes were compared for transfection with either PEG or DMSO treatments. Following transfection the labelled chromosomes could be visualised in recipient cells using a monoclonal antibody to BrdU, followed by immunoperoxidase staining. Chromosome uptake into cells was similar for both DMSO and PEG treatments and was a relatively frequent event; about 1 in 5 recipient cells had labelled material present. This technique can be used to assess the technical aspects of the earliest stages of chromosome-mediated gene transfer.

A preliminary report on the suitability of sheep epidermal squamous cell carcinoma as a solid tumor model in the evaluation of intra-arterial methotrexate administration.

A preliminary study was undertaken to assess the sensitivity of sheep epidermal squamous cell carcinoma, in the head and neck region, to intra-arterial (IA) methotrexate (MTX) infusion. There was an objective tumor response (40-56% regression) in all three IA-infused sheep, whereas tumor progression was observed in all three animals treated intravenously (IV). Regional and systemic side effects were negligible in all cases. Technically, IA drug infusion in the sheep was an improvement on previous small animal models, with no problems related to arterial catheter insertion, blockage, or dislodgement, and tolerable infusion times being of markedly longer duration. The histological differentiation of moderately differentiated stage II lesions improved during therapy irrespective of clinical response, whilst the histology of well-differentiated stage III and IV tumors remained unchanged. Tumor cell cycle stage and ploidy characteristics, as determined by flow cytometric DNA analysis, were little affected by either mode of drug administration. It is concluded that sheep epidermal carcinoma is responsive to IA MTX, and that this animal model is the most appropriate yet utilised to study the comparative effects of IA and IV chemotherapy in the head and neck region.

Bladder cancer xenografts: a model of tumor cell heterogeneity.

Twenty bladder biopsies from patients with primary transitional cell carcinoma were inoculated into nude mice. To date, eleven of these have grown as primary implants and three serially transplantable xenograft lines (UCRU-BL-12, UCRU-BL-13, UCRU-BL-14) have been established. The histological and ultrastructural features of human transitional cell carcinoma have been maintained in each line. Despite a relatively uniform histological appearance, several indices of occult tumor heterogeneity have been revealed. Immunocytochemical staining was negative for beta-subunit human chorionic gonadotrophin but positive for carcinoembryonic antigen only in areas of squamous differentiation. All three tumors bound peanut lectin. Flow cytometric DNA analysis of UCRU-BL-13 showed multiple aneuploid peaks, separate populations being demonstrated in different xenografts of the same generation. However, the morphologies of these tumors remained identical. On initial implantation UCRU-BL-12 and UCRU-BL-14 were near diploid but aneuploid populations became apparent with increasing passage number. Each xenograft line caused cachexia in the host mice. Treatment with the cisplatin analogue, isopropyl platinum, ameliorated the cachexia displayed by mice carrying UCRU-BL-14 but did not cause tumor regression. UCRU-BL-12, when tested with cisplatin, isopropyl platinum, and carboplatin, showed equivalent growth retardation with each drug. These xenografted human bladder cancers may be useful models for the study of heterogeneity of the tumor populations in bladder cancer and for the evaluation of new approaches to treatment.

Ploidy and proliferative characteristics of sheep epidermal squamous cell carcinoma determined by flow cytometric DNA analysis.

Multiple biopsies from each of 22 primary sheep epidermal squamous cell carcinomas were analysed by flow cytometry to determine the G0/G1 modal DNA content ("ploidy") and cell cycle characteristics within each tumour. Ten of 12 tumours where aneuploidy was present demonstrated uniform intra-tumour aneuploid populations regardless of the site of biopsy. Increasing tumour volume (from stage I/II to stage III/IV lesions) was associated with increased histological variability and ultimate heterogeneity of G0/G1 DNA content, whilst the mean numbers of S phase cells decreased. These features were consistent with the effects of variable tissue hypoxia seen with changes in effective vascularity in developing tumours. Decreasing histological differentiation was associated with an increase in numbers of cells synthesising DNA within 44 biopsies with measurable S phase, and, in stage I/II biopsies, correlated with an increased incidence of aneuploidy.

Fragment filtration: a method for the accurate determination of flow cytometric kinetic data from bone marrow aspirates.

The extent to which bone marrow obtained by conventional aspiration is contaminated by peripheral blood has been confirmed and quantitated. In marrow aspirates from normal subjects the median percentage of nucleated cells that had originated from the peripheral blood was 32% (range 2.5%-64%), in patients with acute leukemia 23% (range 0.5%-96.5%), in patients with chronic leukemia 59% (range 17%-76%), and in patients with lymphoma 31% (range 0.5%-74%). Flow cytometric (FCM) DNA analysis of conventional marrow aspirates from a range of subjects significantly underestimated the proportions of S-phase cells present, when compared with results from trephines obtained at the same time. Having shown, using 51Cr-labeled red cells in mice, that circulating red cells do not reenter the marrow parenchyma, a mathematical correction for contaminating blood similar to that described by Holdrinet et al. was devised. This correction improved the S-phase cell estimate from aspirated marrows, and the corrected values were not significantly different from values from paired trephine samples. A previously described technique for collecting fragments by filtration of aspirated marrow has been adapted for FCM analysis as a more direct way of overcoming problems due to blood contamination. This method was shown to yield estimates of S-phase cells not significantly different from those in paired marrow trephines and offers an alternative to routine trephine biopsies for FCM analysis of marrow cell kinetics.

Effects of ultraviolet radiation and immunosuppressive therapy on mouse epidermal cell kinetics.

The effects of immunosuppressive drugs on epidermal cell mitotic activity and the proliferative response of epidermis following ultraviolet radiation (UVR) were tested. Hairless (Skh-hr 1) mice were treated with immunosuppressive drugs at equivalent clinical doses with or without concomitant UVR (290-400 nm). Epidermal parameters measured were mitotic index (Im), rate of entry into mitosis (Fm), flash labelling index (FLI), rate of entry into DNA synthesis (Fs) and DNA content (flow cytometric analysis). In non-irradiated skin, prednisolone therapy depressed both mitotic activity and DNA synthesis; azathioprine and cyclosporin A had no effect; cyclophosphamide therapy increased the Fm and FLI values. Following repeated doses of UVR, there were enhanced mitotic activity and DNA synthesis in epidermis. Prednisolone therapy moderately depressed both proliferative responses; cyclophosphamide enhanced mitotic activity; azathioprine and cyclosporin A had no effect on these responses. The significance of these findings in relation to potential for increased susceptibility of skin to UV-induced carcinogenesis is discussed.

Malignant melanoma: analysis by DNA flow cytometry.

The DNA content of 14 primary and 111 secondary melanomas was determined by flow cytometry. Aneuploidy was detected in 67% of samples. The frequency with which aneuploid cells were found was similar in primary and metastatic melanomas and, in the metastatic group, for melanotic and amelanotic tumours. Aneuploid diversity was marked with a wide variation in DNA content between tumours. Serial biopsies were performed in 14 patients, and in 10 there was discordance in DNA profiles between first and subsequent biopsies. Tumour biopsies taken from different sites at the same time also showed discordance in 3 of 5 cases. These features highlight the degree of cellular heterogeneity in malignant melanoma.

Cell cycle homogeneity in bone marrow samples from different sites: flow cytometric evaluation of multiple samples from sheep.

The distributions of cells in each of the phases of the cell cycle, determined by flow cytometry (FCM), were compared in multiple marrow trephine biopsy samples from 3 sites (both iliac bones and sternum) in 5 sheep. Within any one animal no significant differences could be found between the proportions of cells in the G0/G1, S or G2 + M phases of the cycle from different sites. Differences between animals were detected and these were consistent for any of the sites sampled. We conclude that the proliferative characteristics of marrow cells as determined by FCM in any one animal at one time are comparable at anatomically distinct marrow sites, and that a sample from one site is representative of the whole.

Differential synchronization of leukemic cells in vivo by hydroxyurea.

Flow cytometry (FCM) was used to monitor the cell cycle changes which occurred in the bone marrow cells of a patient with acute myeloblastic leukemia following pre-induction treatment with hydroxyurea. Flow cytometric and cytogenetic analysis showed two populations of cells; one hypertetraploid and presumably leukemic, and the other diploid and possibly normal. Sequential FCM monitoring of bone marrow cells after hydroxyurea demonstrated an early rise (after 24 h) in the S-phase component of diploid cells and a rise in the S-phase component of hypertetraploid cells 48-72 h later. Conventional induction therapy timed to coincide with this latter peak resulted in early remission.

Standardization of flow microfluorometers using glutaraldehyde fixed lymphocytes.

The preparation of glutaraldehyde fixed lymphocytes as a reference standard in flow microfluorometry is described. The ease of preparation, the stability of the cells over time, their ability to stain reproducibly in the range expected of fresh human peripheral blood and bone marrow cells and, most importantly, the fact that they may be used to resolve optimally and situate correctly the G1 peak of normal mammalian cells, make them a reliable tool for the calibration of flow microfluorometers and for detection of aneuploid populations.