Transplantation with blood stem cells.

Peripheral blood stem cell transplantation (PBSCT) offers an alternative to autologous bone marrow transplants (A-BMT), especially in malignant diseases with bone marrow contamination. The presence of hemopoietic precursors in peripheral blood has been documented in several animal models and in humans. While many of these precursors might be committed cells with finite renewal capacity, ample evidence suggests that true pluripotent stem cells are circulating in a number sufficient to enable sustained trilineage engraftment after transplantation. Stem cell mobilization is markedly increased in the early recovery phase after intensive chemotherapy and can be promoted by the administration of various cytokines or polyanionic substances. These effects are used to optimize stem cell harvesting by leukapheresis. Clinical trials of PBSCT have been performed in several hundred patients with various hematological and nonhematological malignancies. Recovery was generally more rapid than after A-BMT. However, the envisioned advantage concerning disease control has not been documented so far.