Organ cultures of chick and rabbit embryonic skin were used to assess the tumorigenicity of cultured human cell lines. Cell lines were from patients with (1) specific chromosomal abnormalities and an increased risk of cancer (Down's syndrome, Klinefelter's syndrome, Partial D Trisomy, Bloom's syndrome, Franconi's anemia, ataxia telangiectasia and xeroderma pigmentosum); (2) a specific chromosomal abnormality but no increased risk for cancer (Cri du chat), and (3) a biochemical defect (galactosemia). In addition, tumor cell lines and cell lines of normal origin were used as positive and negative standards. Mitotic ability was quantified by dividing the total number of mitoses in the cell inoculum seen in histologic sections by the number of sections examined to give a computed mean number of mitoses per section (MMS). Neoplastic cell lines showed MMS values greater than 1.0 while cell lines of normal origin were less than 0.25. The cell lines derived from patients with chromosomal abnormalities and the patient with a biochemical defect, whether the individuals were at an increased risk for cancer or not, gave the same range of MMS values as obtained for cells of normal origin. These results that chromosomal aberrations per se do not enhance the cell's capability for proliferation on a xenogenic substrate.

Animals↗

PubMed1981

Monkey kidney cell growth optimization and poliovirus propagation in microcarrier culture.

Three monkey kidney cells lines Vero, LLC-MK2 and CV-1 were grown in microcarrier cultures. The carrier support was DEAE-Sephadex gel beads at low anion exchange capacity prepared according to a protocol developed at the Massachusetts Institute of Technology. The growth rate of the cells and the final cell density in microcarrier culture was dependent on the concentration of the beads in culture and on the size of the initial cell inoculum. The efficiency of the microcarrier culture system was compared to that of stationary and roller bottle cultures. The microcarrier culture system was applied to the propagation of polioviruses in the three established monkey kidney cell lines and the yields were compared with those obtained in roller bottle and stationary cultures. The yield of the three types of polioviruses in the various cell lines and culture systems was similar. The use of the microcarrier culture system for anchorage-dependent cells together with the use of continuously propagating cell lines offer great advantage for large-scale cultivation of poliovirus for the preparation of killed poliovirus vaccines.

Animals↗

PubMed1981

Tumorigenicity of continuous monkey cell lines in in vivo and in vitro systems.

One of the major considerations on the acceptability of a cell substrate for vaccine production concerns the potential malignancy of those cells. Consequently, we tested a variety of continuous monkey cell lines for tumorigenicity in the immunosuppressed newborn rat and immunosuppressed nonhuman primate and in the chick embryonic skin organ culture. Two positive control tumor cell lines produced progressive tumors in both in vivo systems as well as occasional metastases in the rat. The continuous monkey cell lines did not produce progressively growing tumors in the two in vivo models. However, LLC-MK2, produced occasional microscopic tumors in the nonhuman primate and newborn rat as well as lung metastases in the newborn rat test. In the organ culture assay LLC-MK2 demonstrated proliferative and invasive characteristics similar to the positive tumor lines whereas three other monkey lines were similar to secondary monkey kidney cells.

Animals↗

PubMed1981

Theoretical considerations and practical concerns regarding the use of continuous cell lines in the production of biologics.

The origin and history of continuous cell lines are discussed briefly in the context of their biological relationship to diploid and tumorigenic cells. The question of the potential tumorigenicity of continuous cell lines is examined from the points of view of the theoretical risks involved in the use of these cells for the production of biological products, and of practical approaches to risk assessment. Animal and in vitro tumorigenicity test systems are discussed, and published data on the transfer of tumorigenic properties by DNA are reviewed. Both animal and human experience with vaccines produced in tumor cells is discussed in relation to cancer risk. When the theoretical risks of using continuous cell lines as substrates to produce biological products are balanced against the available data, it would appear reasonable to proceed with the use of such cell lines for the development of biologics because the benefits of those products appear to exceed by far the potential risks associated with the use of these cell substrates.

Animals↗

PubMed1980

On the origin of human tumors.

A proposal is made to extend the commitment theory of cellular aging to the process of tumorigenesis. Indirect data are cited in support of a scheme whereby human tumors arise from a small number of unique cells which are termed "uncommitted." The process of tumorigenesis as described is both multistep and reversible.

Cell Division↗

PubMed1979

Cell substrates for biologics production: factors affecting acceptability.

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Cell Line↗

PubMed1979

Is DNA synthesis a requisite for the differentiation of B lymphocytes into immunoglobulin-secreting plasma cells?

A great amount of conflicting evidence has been reported concerning the relationship between DNA synthesis and the differentiation of immunoglobulin-secreting cells. With the development of flow cytometry, it has become possible to analyze lymphocyte populations by making rapid and accurate measurements of cellular DNA content, and by estimating the fraction of cells that synthesize DNA. Application of these techniques to an in vitro culture system stimulated by the T-dependent sheep red blood cell antigen has allowed us to investigate cell division in populations of antibody-forming cells. DNA synthesis is apparently not a requisite for the differentiation of immunoglobulin-secreting cells.

Animals↗

PubMed1979

Kinetics and cell killing in dividing and nondividing leukemic cells in vitro and in vivo by natural splenic cytotoxic factor.

Ultrafiltered splenic extracts (30,000-50,000 daltons) were specifically cytotoxic in crowded cultures of murine leukemic lymphoblasts but were only inhibitory toward normal lymphocytes or sparse cultures of leukemic cells. This expression of cytotoxicity was quantitated by (i) vital dye exclusion, (ii) cytochemical metods, and (iii) the increased survival time of mice injected with L-1210 leukemic cells incubated in vitro with splenic extract. Selective cytotoxicity of splenic extract was not due to medium depletion or to complement-mediated cytolysis and could not be replicated using similar extracts of other lymphoid and nonlymphoid tissues. The selective effect of splenic extract on leukemic cells was characterized by the progressive shedding of cytochemically demonstrable RNA and the corresponding inhibition of 3H-uridine and 3H-thymidine incorporation. The comparison of progressive and gradual expression of cytotoxicity by splenic extract with the S phase specific inhibitor cytosine arabinoside suggests that the former is cytotoxic against leukemic cells predominantly in the G1 phase of the cell cycle.

Animals↗

PubMed1979

Cytochemical and ultrastructural alteration of leukemic cells by a naturally cytotoxic factor from spleen.

Experiments were carried out to delineate the differences in cytocidal modality of natural splenic cytotoxic factor (30,000-50,000 daltons) and cyto-A against normal and human leukemic lymphocytes in vitro. It was found that the differences in the cytocidal action effected by cyto-A and splenic isolate were as follows: (1) the killing effect of cyto-A against leukemic cells was very rapid in contrast to the slowly acting spleen factor as evaluated by cytochemical and ultrastructural studies; (2) spleen factor was not cytotoxic against normal lymphocytes in contrast to the indiscriminatory cytotoxic cyto-A.

Cell Transformation, Neoplastic↗

PubMed1978

Chick embryonic skin as a rapid organ culture assay for cellular neoplasia.

We used chick embryonic skin (CES) in organ culture to assess the neoplastic potential of a variety of cultured human and nonhuman cell lines. Cells derived from cancer tissues grew in CES and formed tumors in nude mice while cells derived from normal tissues grew in neither system. The CES proved to be more sensitive than the nude mouse when used to assay SV40 transformed human cells; each of four such lines grew in CES while only one of the four lines grew and formed tumors in nude mice. In addition, the patterns of invasion by inoculated cells can be easily studied in the CES. These results suggest that CES in organ culture offers an inexpensive, rapid, and reliable alternative to the nude mouse as a tumorigenicity test.

Animals↗

PubMed1978

The cytogenetic, proliferative and viability effects of four bacteriophages on human lymphocytes.

Certain bacteriophages have been found in live virus vaccines, while a few others have been associated with disease states. Some of these phages have produced abnormal growth of eukaryotic tissue cultures. For this reason bacteriophages phiX-174, MS2, T2 and an isolate from live virus vaccines, phiV-1, were incubated with human cell cultures for examination of chromosomal effects, cell proliferation and viability. Mitogen-stimulated lymphocytes and human embryonic kidney tissue cultures showed no increase in chromosomal abnormalities for high doses of phage-infected versus control cultures. Tritiated-thymidine uptake, correlated with mitotic indices for phage-treated lymphocyte cultures, indicated a reduction in cell division, while 51-chromium release studies showed no cell death occurring in these cultures. This suggested that inhibition of DNA synthesis was occurring in some cells. The presence of phage in the supernate of cells that were exposed to phage suggested the possibility of phage attachment to the plasma membranes of lymphocytes, which may in turn affect the suppression of DNA synthesis.

Bacteriophages↗

PubMed1978

Bacteriophages, vaccines, and people: an assessment of risk.

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Animals↗

PubMed1978

Disseminated lymphoma in a rhesus monkey: a case report.

A rhesus monkey was inoculated with rhesus cytomegalovirus. A leukocyte-associated herpes virus, unrelated to cytomegalovirus, was later isolated from the same monkey. Four years after the virus inoculation, the monkey developed a disseminated lymphoma.

Animals↗

PubMed1977

Bacteriophages in live virus vaccines: lack of evidence for effects on the genome of rhesus monkeys.

Four juvenile rhesus monkeys were inoculated with 10(12) plaque-forming units of the bacteriophage phiV1 isolated from live virus vaccines. After phiV1 had been cleared from the blood, DNA's were isolated from the livers and kidneys and analyzed for the presence of bacteriophage by plaque assays, and for the presence of phiV1 DNA by DNA-DNA reassociation kinetics. No evidence was found for persistence of the bacteriophage or for replication of the phage genome in these rhesus monkeys.

Animals↗