CD34+ stem cells are multipotent and can give rise to all cell types in blood. CD34 cells are most known for its expression on hematopoietic progenitor cells found in bone marrow and cord blood. While compromising only 1.5% of bone marrow mononuclear cell population, CD34 stem cells are responsible for all lymphohematopoietic lineages and are now commonly used clinically as they have been shown to provide long-term durable donor-derived host lymphohematopoietic reconstitution.Donors are injected with G-CSF, which stimulates the bone marrow to produce a large number of hematopoietic and progenitor stem cells and mobilizes them into the peripheral blood stream.CD34+ cells are isolated using positive immunomagnetic cell separation procedures from a mobilized leukapheresis collection.