Hematopoietic stem cell discovery (1961)
James Till and Ernest McCulloch injected bone marrow cells into irradiated mice and observed spleen colonies, proving a single cell could produce all blood cell types. This was the first formal demonstration of a tissue stem cell.
Established the functional assay framework for identifying stem cells in any tissue.
Led to bone marrow transplantation and the entire field of stem cell biology.
The TLSC identification uses the same functional logic, self-renewal and differentiation assays, that Till and McCulloch pioneered for blood stem cells.
