Cord Blood
August 2012
Umbilical cord blood, the blood found in the placenta and umbilical cord after childbirth, is a source of precious stem cells which can be used to treat blood diseases such as leukemia, and which may in future be used to reconstitute damaged tissues and organs. There is consensus in the Australian medical community that this valuable resource, which is usually discarded as medical waste, should be preserved for potential future use. There is controversy, however, about how to organise this activity: should cord blood banks be public facilities analogous to traditional blood banks, or is there a role for the private sector to play?
The first cord blood transplantation was performed in 1988 in France on a six-year-old boy with severe Fanconi’s anaemia (a rare blood disorder). The transplant was successful, and since then, over 12,000 cord blood transplants have been performed worldwide, with more than 150 paediatric transplants performed in Australia. For reasons not fully understood, it is easier to find a suitably-matched donor for cord blood than for bone marrow (the classic source of blood stem cells). Cord blood is therefore increasingly used as an alternative for patients who do not have a matched bone marrow donor. Furthermore, as a source of stem cells free from the issues associated with embryonic stem cells, cord blood is a very promising cell source for medical research and future applications.
Growth in the use of cord blood has led to the establishment of both public and private cord blood banks, with distinct functions. Public banks are generally government-funded organisations that bank cord blood anonymously for use by any suitably-matched member of the community. There are three public banks in Australia located in Sydney, Melbourne and Brisbane. Private banks, of which there are also three in Australia, charge a fee to collect and store a baby’s cord blood for exclusive personal use, or use by a family member. The advantage of having access to one’s own cord blood is that there is no risk of graft-versus-host disease (where the transplanted cells see the patient’s cells as foreign and attack them), the leading cause of death following a transplant.
Despite this advantage, a number of professional bodies such as the American Medical Association recommend against private cord blood banking. A 2009 survey of paediatric haematopoietic cell transplantation physicians in the US and Canada found similarly that few endorse private banking in the absence of an identified medical condition. The Royal Australian and New Zealand College of Obstetricians and Gynecology (RANZCOG) is not opposed to private banking in principle. According to Prof. Michael Permezel, President Elect, the RANZCOG position is that there is certainly potential value in preserving stem cells, but each couple should consider private banking in light of their economic circumstances and the uncertain probability of future benefit.
The primary objection to private banking is that the probability of using one’s own cord blood is too low to justify the cost of banking privately. The probability that a privately-banked sample will be used is much lower than the probability that a publically-banked sample will be used. This is because while publically-banked samples are made available to a pool of millions of potential candidates, privately-banked samples are used only in the unlikely case that the specific individual or a family member develops an illness treatable with a cord blood transplant. Even if an individual does develop such a condition, allogeneic (donor) transplants are sometimes preferred to autologous (one’s own cells). This is the case, for instance, for genetic diseases, where the therapeutic effect is derived from introducing cells that do not have the genetic defects present in the individual.
Based on currently-available therapies, estimates of needing an autologous transplant range between 1/2500 and 1/200,000. The actual experience of the largest private banks in the US suggests usage of between 1/1200 and 1/2500. The joint probability that either the individual or a sibling requires a transplant could be significantly higher (as privately-banked blood is most often used to treat siblings), but it is nonetheless extremely low. This has led some doctors to accuse private banks of “exploiting vulnerable parents” with promises of life-saving therapies that are, in reality, very unlikely to be necessary.
If it were free, the decision to bank privately, and insure one’s child for even the rare possibility a transplant will be required, would be straightforward. But everything has a cost (in this case, approximately AU$1500 upfront for private collection and AU$175 per year for storage). For opponents of private banking, who tend to focus on the current applications of cord blood, this substantial cost is not justified by the remote probability of future benefit. However, in dismissing future applications as “hypothetical” and downplaying the advantages of autologous over allogeneic treatments in some settings, private bank sceptics potentially underestimate the value of private banking.
“People misinterpret the value of cord blood,” says Prof. Richard Boyd, director of the Monash Immunology and Stem Cell Laboratories at Monash University. “The value is not just the blood stem cells, but the once-in-a-lifetime opportunity at birth to capture nature’s repair kit”. Stem cells have the ability to act as nature’s repair kit because they are “multi-potential” – they can differentiate into diverse cell types from muscle to nerve to blood. This raises the prospect that stem cells will provide a source for regenerative medicine, the cutting-edge science of replacing or repairing human tissues and organs following disease or injury.
Substantial research into future applications of cord blood is underway. Researchers at Duke University and the Medical College of Georgia are conducting clinical trials to determine whether stem cell infusions can treat cerebral palsy by stimulating the regeneration of damaged nervous system tissue. A team at the University Hospital of Munich is working on engineering heart valves for children with cardiac disease. The University of Florida has conducted trials into the use of cord blood to treat Type 1 diabetes. A trial is also planned in Australia to be run by the Childrens’ Hospital at Westmead. It is thought that stem cell infusions may be effective in treating Type 1 diabetes and other autoimmune diseases by “reprogramming” the immune system so that it no longer attacks the body’s own cells.
There are major barriers to overcome before any of these therapies reach clinical application, but scientists generally express measured optimism. “The reality is that stem cell science related to regenerative science is developing at an increasingly fast speed,” says Gordana Vunjak-Novakovic,Professor of Biomedical Engineering and Medical Sciences at Columbia University. “Every year there are more developments that bring us closer to translating our knowledge into clinical applications, and most of us share optimism that we will be able to do more and more”.
Even were there no scientific advances, it is possible that standard transplants to treat blood disease will become more frequent. A major impediment to traditional therapies is that umbilical cord samples often do not contain enough stem cells for a successful transplant. For this reason, cord blood transplants are most effective in children or small adults. Scientists have succeeded in “expanding” the number of stem cells in the laboratory and in animal models, but have struggled to prevent the dividing cells from maturing into differentiated cells.
A team of researchers at Fred Hutchinson Cancer Research Center in Seattle led by Dr. Colleen Delaney made a significant breakthrough in 2011 when, for the first time, they were able to divide cord blood stem cells without setting off the differentiation process. Delaney is now preparing to conduct phase II trials to determine the effectiveness of transplants with expanded cord blood units, following positive results during phase 1 trials. “If these expanded units continue to be effective, the therapy could move forward to FDA approval and more widespread use,” she says.
As well as regarding future stem cell applications as purely speculative, opponents of private banking underplay the importance of the immunological advantages of having access to one’s perfectly-matched cells. They typically emphasise the body’s greater tolerance for foreign cord blood compared to bone marrow, and do not address the immune rejection problems associated with allogeneic transplants.
Whilst the body does have a higher tolerance for foreign cord blood than for foreign bone marrow, the risk of death following a transplant increases tremendously when foreign cells are used. Due to the safety concerns, it is unlikely that the FDA would approve some new allogeneic therapies. Apart from the immune issues, autologous cells also integrate better into surrounding tissues, says Dr. Ralf Sodian, a cardiovascular surgeon who engineers heart valves using stem cells, making them the preferred choice for applications such as cardiac transplants.
In clinical trials, doctors (including those opposed to private banking) opt to use autologous transplants where possible to avoid immune complications. This means that those who have stored their cord blood are on a shorter path to clinical applications. Furthermore, they will have access to the full range of options in the unlikely event of requiring treatment. It is most likely that both autologous and allogeneic treatments will continue to be used, depending on the specific context. Those who have privately banked will always be able to access cord blood from public banks if an allogeneic treatment is recommended, but those who have not will be limited to allogeneic options.
Another common concern about private banking is that private banks divert cord blood donations from public banks, leading to shortages. At least in Australia, this is not the case. The National Cord Blood Collection Network estimates that, with 20,000 cord blood units, Australia’s public banks could meet 80-90 per cent of donor requests. There are already approximately 23,000 registered units in public banks. An exception, for which there remains real shortages, is cord blood for people of a minority ethnicity (for whom it is more difficult to find a match), but this cord blood must be sourced from other members of the same ethnicity rather than from a higher volume of overall donations.
Even with adequately-stocked public banks, it is said that private banking raises concerns about social inequity. If cord blood proves useful for new autologous therapies, would it be fair that only those able to afford private banking have access to the best healthcare? This is a question for Australian society, but it might be kept in mind that the private banking industry could have wider benefits than the services they provide to customers.
For one, private banks are a source of funding for scientific research, with Australian banks supporting clinical trials for diabetes, cerebral palsy and brain injury. Without private sector involvement, there would be less incentive for innovation in the expansion and storage of stem cells. Furthermore, the private operations of public-private “hybrid” banks could conceivably fund public collections, reducing the burden on government.
The future of private cord blood banking in Australia will be determined by progress in stem cell science in years to come. What is the right decision for the parent-to-be today, unable to look into the future? On the one hand, there are major scientific obstacles to overcome before we see wider therapeutic application of cord blood. On the other hand, stem cell medicine is a vibrant field with enormous potential. In the light (or dark) of such uncertainty, the decision is perhaps best left, as RANZCOG recommends, to each individual, who is in the best position to assess the economic sacrifices required to bank privately.
Sarah Lucas is a graduate of the University of Melbourne and the University of Cambridge. She works at the World Bank in Paris and is a freelance writer.
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