Bone marrow donation is a life-saving medical procedure involving the transplant of healthy hematopoietic stem cells to patients suffering from blood cancers or disorders. These stem cells generate all blood cell types, and a transplant replaces a patient’s diseased cells with a donor’s healthy ones. Determining eligibility requires a layered screening process, beginning with broad criteria before moving to specific health assessments. This stringent screening ensures the safety of both the donor and the medically fragile patient.
General Requirements for Joining a Registry
The initial step for a potential donor is joining a national or international registry, which has broad requirements centered on age and general wellness. Registries focus on recruiting new donors between the ages of 18 and 35, as medical research indicates that younger donors provide the best chance for a successful transplant and long-term patient survival. While the maximum age for registration is often 35, a person who has already registered may remain an active potential donor until they reach 61 years old.
Potential donors must also be in general good health, free from medical conditions that could pose a risk during the donation process or compromise the recipient’s health. Registries often incorporate weight guidelines, typically disqualifying individuals with a Body Mass Index (BMI) over 40. This is due to increased risks associated with anesthesia and surgical procedures. These initial requirements are the first filter to ensure medically sound individuals enter the detailed screening pipeline.
Specific Health Conditions That Prevent Donation
Beyond the general requirements, a comprehensive medical screening identifies specific chronic conditions that disqualify a person from donating. Diseases that affect the immune system or blood cell production are common grounds for exclusion, as the donation could endanger the donor or the recipient. This includes a history of most cancers, especially those of the blood like leukemia or lymphoma. Some localized, early-stage skin cancers like basal cell carcinoma may be exceptions if completely removed.
Systemic autoimmune diseases, such as lupus, multiple sclerosis, or severe rheumatoid arthritis, also prevent donation. This is because the donor’s immune cells could potentially attack the recipient’s body in a complication known as graft-versus-host disease (GVHD). Chronic infectious diseases like HIV or active hepatitis B and C are disqualifiers due to the unacceptable risk of transmission to the immunocompromised recipient. Conditions requiring insulin for diabetes or severe heart, lung, or kidney diseases are also exclusionary, as they increase the risk of serious complications during the donation procedure itself.
Distinction Between Directed and Registry Donation
Donations fall into two categories: anonymous registry donation or patient-directed donation. Registry donation involves matching an anonymous public member to a patient based on a close genetic profile, specifically the Human Leukocyte Antigen (HLA) type. HLA matching is complex and requires a near-perfect alignment to minimize the risk of transplant rejection.
A directed donation is typically sought from a blood relative, such as a sibling. While the motivation and search timeline differ, the fundamental health requirements for the donor remain largely the same. Relatives must still undergo rigorous medical evaluations to ensure they are healthy enough to safely donate.
Understanding Donor Commitment and Procedure Types
Once a potential donor is identified as a match, they must be fully committed to moving forward, as the patient’s conditioning regimen begins immediately and cannot be reversed. The process concludes with one of two primary methods for collecting the healthy stem cells.
The most common method, accounting for approximately 90% of all donations, is Peripheral Blood Stem Cell (PBSC) donation. This is an outpatient procedure similar to donating plasma. PBSC requires the donor to receive daily injections of a medication called filgrastim for several days beforehand. This stimulates the stem cells to move from the bone marrow into the circulating bloodstream. The cells are then collected through apheresis, where blood is drawn, passed through a machine to separate the stem cells, and returned through the other arm.
The second method is a surgical bone marrow harvest, performed under general or regional anesthesia. Liquid marrow is aspirated directly from the back of the pelvic bone. The patient’s doctor determines which procedure is required based on the patient’s needs, and the donor must be willing to undergo either one.