Their white blood cell count reached normal levels within about 16 days, and blood platelets achieved normal levels within 24 days following transplant. None of the patients experienced unexpected declines in either white blood cells or platelets as a result of the experimental therapy, nor did they develop any resulting infections. The blood-forming stem cell primarily resides in bone marrow, which is the spongy tissue found in the center of bones, although a small amount of these stem cells also circulate in the bloodstream. These constitute the immune system and protect a person from infection. In the immune system, red blood cells transport oxygen throughout the body.
Platelets also play a critical role in the healing process and promote blood clotting.
He adds that elimination of tumor cells during the expansion process in the laboratory might prove a major benefit. Previous research by other scientists has linked the tumor cells contained in the stem cells used for routine bone marrow transplantation with recurrence of a patient's cancer. Likewise, it's sometimes required that a patient undergo several days of apheresis, a process for separating blood into its various components. Large-volume collections are often contaminated with tumor cells that are then reinfused into the patient as part of the transplant process and can lead to relapse of the patient's cancer. The benefits of transplants, especially for patients with early, high-risk breast cancer, may be reduced because of this contamination.