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Bone Marrow Sampling and Transplants
Bone marrow transplants replace diseased marrow with healthy marrow from a compatible host. It can cure several cancers and genetic disorders like thalassemia.
The donor-recipient compatibility or disease diagnosis is confirmed using a biopsy — a diagnostic test for a sample of red bone marrow.
Red bone marrow is typically harvested from the iliac crest of the donor's hip bone.
Before transplanting the healthy marrow, the patient's affected marrow is destroyed by chemotherapy or radiation to avoid eliciting immune responses to donor marrow.
The healthy marrow is then injected into the patient's veins, from where it migrates to the bone marrow cavities for donor stem cells to multiply.
Once the donor cells establish themselves, the recipient's marrow gets replaced with healthy cells.
An incompatibility of transplanted marrow may cause graft-versus-host reactions.
Graft-rejection risks can be substantially minimized by utilizing the stem cells obtained from the umbilical cord at birth, which can be stored in cord blood banks for future transplantation.
Alternatively, the patient's somatic cells can be genetically reprogrammed to induced pluripotent stem cells for transplant.
22.29:
Bone Marrow Sampling and Transplants
Bone marrow transplant is a potential cure for several diseases, including cancer and specific genetic disorders. Notably, this procedure is applicable for patients suffering from aplastic anemia, certain types of leukemia, severe combined immunodeficiency disease (SCID), Hodgkin's disease, non-Hodgkin's lymphoma, multiple myeloma, thalassemia, sickle-cell disease, and certain cancers.
The transplant begins with high doses of chemotherapy and radiation treatment, which aim to destroy the cancerous or defective red bone marrow, reducing the risk of transplant rejection. Following this, healthy red bone marrow—typically harvested from the iliac crest of the donor's hip bone—is injected into the patient's veins. This marrow subsequently migrates to the recipient's red bone marrow cavities, where if the procedure is successful, the donor's stem cells multiply and completely replace the recipient's marrow with healthy, noncancerous cells.
However, the procedure has risks. The destruction of the recipient's white blood cells leaves them highly vulnerable to infections until the transplanted marrow begins to produce enough white blood cells—which typically takes 2–3 weeks. Additionally, graft-versus-host disease is possible, whereby the transplanted marrow produces T cells that attack the recipient's tissues.
Interestingly, cord blood cells present a recent innovation in the field, offering an alternative to red bone marrow. These stem cells, easily collected from the umbilical cord shortly after birth, are abundant and less likely to cause graft-versus-host disease. As a result, the match between donor and recipient need not be as precise as in a bone marrow transplant. Notably, they can be stored indefinitely in cord blood banks, providing a larger pool of potential donors, and are less likely to transmit infections. This advancement signals a promising alternative to traditional bone marrow transplants, particularly in mitigating the risks of graft-versus-host disease.