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Long-term culture of bone marrow-derived preleukemic cells from F-MuLV-infected mice
Abstract:
The replication-competent Friend leukemia virus (F-MuLV) induces leukemias involving three hematopoietic lineages after a latent period of several months. In an attempt to elucidate the early events of the leukemogenic process, we looked for a method allowing the isolation and the long term in vitro maintenance of preleukemic cells. When established as long-term cultures according to the technique described by Dexter et al, bone marrow cells obtained from 7/7 apparently healthy F-MuLV-infected preleukemic mice led to the accumulation of immature myeloblastic cells, and to the generation of permanent myeloblastic cell lines, which in most cases further became tumorigenic in preirradiated recipient animals. The delays required to obtain cell lines were shorter when the duration of the in vivo infection was longer, suggesting that these cells were committed into the leukemogenic pathway before their transfer into culture flasks. The myelomonocytic preleukemic cells exhibited normal sensitivity to purified preparations of CSFs, but acquired the capacity to grow in the absence of exogenous CSF stimulation. Examination of integrated provirus copies demonstrated that the preleukemic cell proliferation involved a single or a few clones which may progress in vitro from a preleukemic to a fully malignant stage without major modifications of the integrated provirus copies.
Insights
Researchers developed a method to isolate and maintain preleukemic cells in vitro. These cells, derived from Friend leukemia virus (F-MuLV)-infected mice, accumulated and formed permanent myeloblastic cell lines, advancing the leukemogenesis process.
Area of Science:
- * Hematology
- * Oncology
- * Virology
Background:
- * Friend leukemia virus (F-MuLV) causes leukemia in mice after a lengthy incubation period.
- * Understanding early leukemogenic events requires methods to study preleukemic cells.
- * Current knowledge lacks in vitro models for preleukemic cell isolation and long-term culture.
Purpose of the Study:
- * To establish a method for isolating and maintaining preleukemic cells in vitro.
- * To investigate the early stages of Friend leukemia virus-induced leukemogenesis.
- * To characterize the properties of preleukemic cells during in vitro culture.
Main Methods:
- * Long-term bone marrow cultures using the Dexter technique.
- * Isolation of cells from F-MuLV-infected preleukemic mice.
- * Assessment of cell proliferation, tumorigenicity, and CSF dependence.
- * Analysis of integrated provirus copies.
Main Results:
- * Long-term cultures generated immature myeloblastic cells and permanent, often tumorigenic, myeloblastic cell lines.
- * Shorter culture times were needed for cell lines from longer in vivo infections, indicating pre-commitment.
- * Preleukemic cells grew without exogenous CSF stimulation despite normal CSF sensitivity.
- * In vitro proliferation involved few clones with minimal provirus modification.
Conclusions:
- * The developed culture method effectively isolates and propagates F-MuLV-induced preleukemic cells.
- * Preleukemic cells acquire self-sufficiency for growth and can progress to malignancy in vitro.
- * Leukemogenesis involves clonal expansion of pre-committed cells with stable proviral integration.