IN-VITRO DIFFERENTIATION OF MURINE SCA-1(-) CELLS INTO MYELOID, B-CELL AND T-CELL LINEAGES()LIN()

Hematopoietic progenitor cells were shown to be capable of differentia ting into myeloid, B cell and T cell lineages. We used a two-step cult ure system in which enriched murine hematopoietic progenitors in bone marrow were first plated in viscid culture medium containing methylcel lulose, 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 SCP and IL-7 for B cell lineage and SCP, IL-3, G-C SF, GM-CSF and EPO for myeloid lineage, Nest, cells from five to ten p rimary blast colonies were cultured again in embryonal thymus (25 GS i rradiated). One aliquot of blast colonies in a primary culture contain ed four colony forming units (CFU) of granulocytes, erythroblasts, mac rophages and megakaryocytes, eight CFU-granulocytes and macrophages, a nd 28 BFU-E in a representative secondary myeloid culture, Another ali quot 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 ant igen, 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 th ese results, ri-e concluded that cells in the primary colonies from Sc a-1(+)Lin(-) hematopoietic stem cells could differentiate into B cell, T cell. and myeloid lineages.