NOTE: The following are answers to questions frequently asked by patients (or their families or caregivers) that have been diagnosed with diseases that may be treated with a stem cell transplant. Please use the links noted after each short answer to obtain more detailed information.
1. Why do patients need blood stem cell transplants?
2. What is cord blood and why is it another viable source of stem cells for transplant?
3. What are the advantages of using cord blood?
4. How many patients have gotten transplants using cord blood?
5. What have been the results for cord blood transplants?
6. How do you find a cord blood match?
7. What are the chances of finding a good stem cell match from an unrelated donor?
8. What affects the outcome of a cord blood transplant?
9. Are their other uses for cord blood?
10. What questions should I ask my doctor about cord blood?
1. Why do patients need blood stem cell transplants?
There is a broad and expanding category of lethal diseases (certain blood cancers like leukemia, other bone marrow failure diseases, immune deficiency diseases and certain metabolic abnormalities) that are now treatable with a blood stem cell transplant, particularly when standard chemotherapy treatment stops working effectively. The stem cell transplant procedure is a complex one, which intentionally destroys a patient’s faulty bone marrow and immune system and attempts to replace it with new stem cells (sometimes the patient’s own, but more often, stem cells obtained from a matched donor). Once the new matching stem cells begin to engraft, the patient may start to produce healthy, disease-free blood cells and may begin to develop a new, working immune system.
2. What is cord blood and why is it another viable source of stem cells for transplant?
Cord blood stem cells are found in a newborn baby’s umbilical cord and placenta. After birth mothers can, with consent, agree to donate their baby’s cord blood, rather than it being discarded as medical waste, to a public cord blood banking program. The stem cells extracted from the cord blood and placenta have been shown to be similar to those found in bone marrow and have been used successfully for more than a decade as an alternative to bone marrow stem cells for transplant. This now gives transplant patient candidates another viable source for a potential stem cell match which is a requirement in order to proceed to transplant.
3. What are the advantages of using cord blood?
a. Cord blood stem cell units have already been collected, processed, tested, typed and are readily available in cryo-preserved inventories of public cord blood banks. This eliminates the need for the typically lengthy, often costly and too often unsuccessful search to find a matching unrelated bone marrow donor.
b. Stem cell transplants using cord blood do not need to be as perfectly matched to the patient’s specific HLA type as they do with bone marrow. This usually provides patients with more potential units to choose from when selecting the appropriate stem cell match for transplant.
c. Cord blood has been shown to cause fewer complications of stem cell rejection (Graft versus Host Disease or GvHD) for patients undergoing a stem cell transplant, improving the odds of a successful transplant.
Are there any disadvantages?
a. The number of stem cells found in the umbilical cord and placenta following birth is limited. With bone marrow donors (usually adults), a larger number of stem cells can be harvested. While the size of a cord blood donation may pose cell dose problems for larger adult patients, transplant physicians are continuing to develop new techniques to successfully address the issue of limited cell dose, such as using two cord blood units to transplant an adult.
b. Since cord blood stem cells can be collected from the newborn only once at birth, it is not possible to obtain additional stem cells from the infant donor to accommodate potential additional needs of the transplant recipient, as is possible with bone marrow donors.
c. Although cord blood donations are rigorously tested and screened before being accepted for placement into the public inventory, there can be rare genetic diseases of the blood or immune system that cannot be detected at birth. This allows for the possibility of transferring such an undetected and later developing disease to the transplant patient recipient. While possible, this is extremely infrequent and for the transplant patient, the benefit of the transplant is significantly greater than this type of possible risk.
4. How many patients have gotten transplants using cord blood?
The first cord blood transplant was performed in 1988 in France. Worldwide to date, there has been over 10,000 cord blood transplants performed. Each year, a greater number of cord blood transplants are being performed. Also, the percentage of cord blood transplants being performed in adults has increased. According to the NMDP, approximately 33% of the transplants have been in adults this past year; a number that continues to increase.
5. What have been the results for cord blood transplants?
All stem cell transplants are considered to be high-risk procedures for a number of different and complex medical reasons. In the last decade, as cord blood has emerged as a viable alternative source of stem cells for transplant, overall stem cell transplant outcomes have shown to be similar for both bone marrow and cord blood transplants. Each stem cell source has its own advantages and disadvantages. However, because cord blood units have been already collected and are readily available in public cord blood inventories, it is usually quicker to actually obtain a matched cord blood unit. As patients’ conditions are often critical prior to transplant, shortening the time to find an appropriate stem cell match can be a decided advantage for the transplant patient.
6. How do you find a cord blood match?
When patients come under the care of a transplant physician, the transplant team will begin a formal search process to determine all possible stem cell matches which may be available for the patient according to his/her HLA type. Ideally, all stem cell sources will be considered and searched and a list of available stem cell matches can be then prepared and evaluated, depending on varied and complicated criteria and based on the individual patient’s best interests.
How does the process compare with a bone marrow search?
Since cord blood stem cell units have already been collected and are readily available in inventory, this first eliminates the need to test and type possible marrow donor volunteers. If a matching marrow donor is found, that donor needs to first be physically located, re-consented as a donor, be physically able to complete the donor process and agree to be hospitalized to undergo the marrow harvest.
7. What are the chances of finding a good stem cell match from an unrelated donor?
Since each transplant patient’s HLA is different, and the success of a stem cell transplant is greatly influenced by the degree of HLA match between donor and recipient, siblings are the most logical place to find a suitable bone marrow donor match. Since the percentage of sibling matches is approximately 30%, the remaining patients (70%) must find an unrelated bone marrow or cord blood match. Since marrow matches must be near perfect to be used for transplant, and since cord blood does not require as close a match, its utilization is growing rapidly.
8. What affects the outcome of a cord blood transplant?
While there are many factors affecting the outcomes of stem cell transplants, proximity of match, cell dose and cord blood transplant experience are the three most critical for cord blood transplantation. Transplant facilities which are experienced in using cord blood have cord blood transplant protocols in place and are knowledgeable in managing the complicated issue of cell dose.
9. Are their other uses for cord blood?
Stem cell applications for regenerative medicine using both bone marrow, cord blood and the patient’s own stem cells is a promising field of medicine. Many advances are being made in numerous regenerative medicine research projects.
10. What questions should I ask my doctor about cord blood?
As a patient considering a stem cell transplant, you need to have every transplant option available to you in terms of finding the best stem cell match possible. No transplant can take place without a suitable match, and cord blood will provide you with expanded opportunities to find the best stem cell unit possible. The success of your transplant is dependent on HLA matching and cell dose. Inquire if your transplant physician has experience with cord blood. While many now do, some still do not. In order to include cord blood as an option, find a qualified and experienced transplant physician in this highly specialized field of medicine.