Transplants of Hematopoietic Stem Cells

They reside in the bone marrow and can be harvested from it. However, a few infusions of granulocyte colony-stimulating factor (G-CSF) — available thanks to recombinant DNA technology — causes them to be released into the blood where they can more easily be collected.

• sickle-cell disease;
• multiple myeloma, a cancer of plasma cells;
• various leukemias;
• and some other types of cancer.

High doses of chemotherapy and radiation can be used to kill off the cancerous cells in a patient, but they also destroy the patient's bone marrow, and the patient will die without a transplant of hematopoietic stem cells.

These can be:

• autologous — from hematopoietic stem cells that were
  • removed from the patient before cancer therapy began,
  • stored alive,
  • and, if there were cancer cells in the bone marrow (the case with multiple myeloma and leukemias), treated to "purge" them. Most failures of autologous stem cell transplants occur because of failure to get all the cancer cells out of the harvested cells rather than failure to eliminate them from the patient.
• allogeneic — hematopoietic stem cells removed from someone else, often a close relative. Another source of hematopoietic stem cells is cord blood — blood drained (through the umbilical cord) from the placenta of newborn infants.

  Allogeneic stem cells

  • avoid the problem of lurking residual cancer cells but
  • should be closely matched to the major histocompatibility loci (MHC) of the patient. If not, the donor cells will attack the recipient causing often-fatal graft-versus-host disease (GVHD). (Even with an exact match at the MHC, some GVHD is likely [Link].)

So hematopoietic stem cell transplants (HSCT) can be life-saving but create their own problems. (Another example: an "immediate"-type allergy like hay fever or asthma of the donor can create the same allergy in the recipient.)