A liquid culture system is described whereby proliferation of haemopoietic stem cells (CFU-S), production of granulocyte precursor cells (CFU-C), and extensive granulopoiesis can be maintained in vitro for several months. Such cultures consist of adherent and non-adherent populations of cells. The adherent population contains phagocytic mononuclear cells, “epithelial” cells, and “giant fat” cells. The latter appear to be particularly important for stem cell maintenance and furthermore there is a strong tendency for maturing granulocytes to selectively cluster in and around areas of “giant fat” cell aggregations. By “feeding” the cultures at weekly intervals, between 10 to 15 “population doublings” of functionally normal CFU-S regularly occurs. Increased “population doublings” may be obtained by feeding twice weekly. The cultures show initially extensive granulopoiesis followed, in a majority of cases, by an accumulation of blast cells. Eventually both blast cells and granulocytes decline and the cultures contain predominantly phagocytic mononuclear cells.



Culturing at 33°C leads to the development of a more profuse growth of adherent cells and these cultures show better maintenance of stem cells and increased cell density.



When tested for colony stimulating activity (CSA) the cultures were uniformly negative. Addition of exogenous CSA caused a rapid decline in stem cells, reduced granulopoiesis and an accumulation of phagocytic mononuclear cells.

Conditions controlling the proliferation of haemopoietic stem cells in vitro.

A bioassay method for supporting human tumor stem cell colony growth is disclosed. The method is suitable for culture of a variety of neoplasms of differing histopathology. Tumor stem cell colonies arising from different types of cancer have differing growth characteristics and colony morphology. The present bioassay may be employed in clinical studies of the effects of anticancer drugs or irradiation on human tumor stem cells.

https://science.sciencemag.org/content/sci/197/4302/461.full.pdf

Primary bioassay of human tumor stem cells

The complementary DNAs and genes encoding the four major human myeloid growth factors--granulocyte colony-stimulating factor, macrophage colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, and interleukin-3--have all been molecularly cloned. These DNA clones have proved valuable for studying the molecular biology of these important regulatory molecules as well as for the large-scale production of the recombinant growth factor proteins. These advances have led to a much better understanding of the role of the myeloid growth factors in regulating hematopoiesis in vivo that should soon find practical application in clinical medicine.

https://science.sciencemag.org/content/sci/236/4806/1229.full.pdf

The human hematopoietic colony-stimulating factors

Differentiation and Proliferation of Hematopoietic Stem Cells

Experiments were conducted to isolate and characterize the gene and gene product of a human hematopoietic colony-stimulating factor with pluripotent biological activities. This factor has the ability to induce differentiation of a murine myelomonocytic leukemia cell line WEHI-3B(D+) and cells from patients with newly diagnosed acute nonlymphocytic leukemia (ANLL). A complementary DNA copy of the gene encoding a pluripotent human granulocyte colony-stimulating factor (hG-CSF) was cloned and expressed in Escherichia coli. The recombinant form of hG-CSF is capable of supporting neutrophil proliferation in a CFU-GM assay. In addition, recombinant hG-CSF can support early erythroid colonies and mixed colony formation. Competitive binding studies done with 125I-labeled hG-CSF and cell samples from two patients with newly diagnosed human leukemias as well as WEHI-3B(D+) cells showed that one of the human leukemias (ANLL, classified as M4) and the WEHI-3B(D+) cells have receptors for hG-CSF. Furthermore, the murine WEHI-3B(D+) cells and human leukemic cells classified as M2, M3, and M4 were induced by recombinant hG-CSF to undergo terminal differentiation to macrophages and granulocytes. The secreted form of the protein produced by the bladder carcinoma cell line 5637 was found to be O-glycosylated and to have a molecular weight of 19,600.

https://science.sciencemag.org/content/sci/232/4746/61.full.pdf

Recombinant human granulocyte colony-stimulating factor: effects on normal and leukemic myeloid cells

A simple in vitro technique is described for the growth of colonies from single cell suspensions of mouse bone marrow. The system involves the plating of marrow cells in agar on feeder layers of other cells, those from 8-day-old mouse kidney and 17th day mouse embryo being shown to be the most efficient types of feeder layers.

TR Bradley

Papers

The growth of mouse bone marrow cells in vitro