In vitro differentiation of murine Sca-1+Lin- cells into myeloid, B cell and T cell lineages.

Hematopoietic progenitor cells were shown to be capable of differentiating into myeloid, B cell and T cell lineages. We used a two-step culture system in which enriched murine hematopoietic progenitors in bone marrow were first plated in viscid culture medium containing methylcellulose, erythropoietin (EPO), stem cell factor (SCF) and interleukin (IL)-7. One thousand enriched murine marrow cells formed 53.5 +/- 12.1 (mean +/- SD) primary colonies. Cells from a single blast colony were separated into two aliquots and replated in secondary methylcellulose cultures containing SCF and IL-7 for B cell lineage and SCF, IL-3, G-CSF, GM-CSF and EPO for myeloid lineage. Next, cells from five to ten primary blast colonies were cultured again in embryonal thymus (25 Gy irradiated). One aliquot of blast colonies in a primary culture contained four colony forming units (CFU) of granulocytes, erythroblasts, macrophages and megakaryocytes, eight CFU-granulocytes and macrophages, and 28 BFU-E in a representative secondary myeloid culture. Another aliquot formed a few B cell colonies (2-10) in a secondary B cell culture. B lymphoid colonies were composed of blast-like cells with B-220 antigen. T cells in a secondary T cell culture consisted of 16% L3T4+, 16% CD8+ and 11% CD3+ of bone marrow origin in the thymus. From these results, we concluded that cells in the primary colonies from Sca-1+Lin- hematopoietic stem cells could differentiate into B cell, T cell and myeloid lineages.