Cord Blood - Saving Lives Stem cells can be painlessly harvested from umbilical cord blood for the treatment of leukemia, anemia, and other diseases. The conventional method of extracting stem cells from bone marrow is a painful procedure for the donor, involving a large needle and anesthesia. Stem cells are unspecialized cells that can repair or replace damaged tissue; the body is less likely to reject them than transplanted specialized tissues. Increasingly, hospitals are establishing cord blood donation programs, providing new hope for patients waiting for bone marrow and stem cell transplants.