How Does it Match Up? Success Rates and Cord Blood Transplants
If your child needs a stem cell treatment, there is nothing more important than a successful outcome. Stem cell transplants are often used in medical situations where success means survival. Many factors can impact survival rate, including the source of the stem cells. Are they from bone marrow or cord blood? Are they from a relative or an unrelated donor? And does that donor provide the best possible HLA match?
Playing the matchmaker
A successful allogeneic transplant of cord blood or bone marrow starts with a successful match of tissue type. Located on the cells in your body are antigens that act as markers. These markers allow the body to recognize/distinguish self cells and foreign cells. Human leukocyte antigen (HLA) typing is used to match these markers in the donor to the recipient.
The match criteria is determined by the transplant doctor for each unique medical case – a perfect match is always the goal. The better the match, the less likely it is a donor’s cells will attack a patient’s cells after transplant (also known as Graft vs. Host disease (GVHD). According to the National Marrow Donor Program (NMDP), a bone marrow transplant requires a minimum 5 out of 6 match. Cord blood, however, requires less strict matching criteria.
Cord blood vs. bone marrow stem cells
Both umbilical cord blood and bone marrow contain Hematopoietic Stem Cells (HSCs). Although both cord blood and bone marrow stem cells are part of the same stem cell family, there is at least one distinct and important difference between them—experience. And in this case, more experience isn’t necessarily better.
For cord blood stem cells, a perfect HLA match isn’t crucial because they are immunologically naïve. This means they don’t have as much life experience with illness or disease and are less likely to recognize the new host as foreign. Bone marrow stem cells do have life experience, so they are more likely to reject or be rejected by the recipient’s immune system. Because of this, when the HLA match is the same, evidence exists that cord blood stem cells offer higher survival rates than bone marrow stem cells.
For example, in this clinical study performed on children with leukemia, the children who received matched cord blood had a 20% higher survival rate than those children who received matched bone marrow stem cells.1
Keep it in the family
When a patient is in need of a donor, a family member is the first place to look. Each child inherits HLA markers from the mother and father. This means that every child has a 25% chance of perfectly matching a brother or sister and up to a 75% chance for an imperfect but useable match.
Transplants using cord blood from a family member have proven to be about twice as successful as transplants using cord blood from a non-relative.2 According to a clinical study published by independent scientists, after one year, estimated survival rates for 78 recipients of cord blood from a related donor were 63%; survival rates for 65 recipients of unrelated cord blood were 29%.3 For comparison, the survival rate one year after transplant for patients using their ViaCord banked unit is currently 87%.3
Knowledge is power
When it comes to making a decision about cord blood banking, it’s important to be informed—even with a difficult subject like survival rates. When considering whether or not to bank your baby’s cord blood, remember these facts:
- Cord blood from a family member with the best possible HLA match is often the best formula for a successful outcome.
- At 87%, no other company discloses higher survival rates than ViaCord4 .
- Advancements in stem cell science and transplantation now provide your family with more options than ever before.
For those of you who are still undecided about what to do with your baby’s cord blood, you might find these additional posts helpful:
- The value of cord blood—even greater than once imagined!
- More stem cells means a better rate of transplant success
- A Gift of Love, the Gift of Life: An Enduring Sibling Connection
1. Children’s Cancer Research Fund. “Research Shows Umbilical Cord Blood Comparable to Bone Marrow.” http://www.childrenscancer.org/latest-news/news-releases/research-shows-umbilical-cord-blood-comparable-to-bone-marrow.html 2. Gluckman, et al., New England Journal of Medicine 1997; pp. 373-381 3. Gluckman, Eliane. “Outcome of Cord-Blood Transplantation from Related and Unrelated Donors.” New England Journal of Medicine. 1997. 4. ViaCord. Data on file, compiled January 2010. 87% is for sibling transplants only.