I’ve always had an interest in the science of bone marrow transplants, ever since my nephew, Simon, was diagnosed with aplastic anemia at the age of two. Although it was a traumatic time for his parents and extended family, the story has a happy ending. His four-year-old brother was a bone marrow match and the transplantation was a success. Today, Simon is a healthy, active, bright boy of 11, with a happy disposition and no memory of the month he spent in the hospital.
I was reminded of Simon earlier this month as I listened to the stellar speakers at StemCellTalks, an annual outreach workshop for Canadian students in grades 11 and 12 to educate them about stem cell science and ethics, and perhaps inspire them too. StemCellTalks is in its fourth year and it takes place in six centres across Canada. Because my employer (Centre for Commercialization of Regenerative Medicine) was a sponsor – along with the Stem Cell Network, STEMCELL Technologies, SickKids Hospital (where Simon was treated), OSCI and others – and the event was taking place across the street from CCRM, it was easy to pop over to meet some of the students and listen to the speakers.
The morning session featured Dr. Penney Gilbert (University of Toronto) providing an overview of stem cell biology. An amusing and lively debate, between Drs. Peter Tonge (Mount Sinai Hospital) and Peter Zandstra (CCRM and University of Toronto), followed. They discussed “Pluripotent vs. Multipotent Cells for treating leukemia” and afterwards Drs. Armand Keating (University of Toronto) and Ronan Foley (McMaster University) had a conversation, more than a debate, about “Adult stem cells from Bone marrow transplants vs. Umbilical cord blood for treating leukemia”.
The students voted after each debate and the speakers left with another notch on their metaphoric belts or their heads hung low. (Not really. All the debaters did a great job and could feel proud of their efforts.)
The outcome of the first debate was a surprise: the students chose pluripotent cells over multipotent cells for treating leukemia. Despite strong arguments for the reliability and successful track record of using multipotent cells in bone marrow transplants, and the potential risks of using unproven pluripotent cells that might cause tumours, the students were perhaps attracted to the notion that induced pluripotent stem cells (iPSCs) have the potential for success without the requirement of a matching bone marrow donor. As well, extracting cells from skin, sometimes the patient’s very own, is simpler and less painful than a bone marrow donation.
The outcome of the second debate was more predictable: bone marrow transplants trounced umbilical cord blood. The issue with umbilical cord blood is that it doesn’t produce enough cells for adult transplants and it is less available. According to Susan Smith of the Canadian Blood Services and one of the afternoon panelists, only 3% of cord blood is banked. As cord blood banking becomes more commonplace in Canada, or banking becomes automatic and families will have to opt out of the process – a possibility that was raised – its availability might sway the current practice. After all, cord blood has the advantage that it can be effective without a perfect match.
The afternoon session began with an introduction of umbilical cord blood banking by Dr. Shane Green (University Health Network) and then the students were divided into groups to answer questions relating to four vignettes on the ethics of umbilical cord blood banking. The students had to approach them from different perspectives: the patient, the clinician, the scientist/biotech entrepreneur and the government regulator. The vignettes tested their understanding of the field (i.e. how closely they paid attention to Dr. Green!) and the challenges associated with the industry.
Those sessions fed in to the ethics panel, featuring Dr. Mark Minden (University of Toronto) representing the scientist/clinician; Dr. Sue Mueller (Insception Biosciences) representing a private cord blood bank; Dr. Allison Brown (CCRM) representing a biotechnology company; and Ms. Sue Smith, mentioned earlier, representing a public cord blood bank.
The panelists answered thoughtful questions from the audience and left us with the take away messages that not enough banking happens in Canada so whether you choose private or public cord blood banking doesn’t really matter as both types benefit Canadians and more choice is a good thing.
Bone marrow transplants, also referred to as stem cell transplants or hematopoietic (blood) stem cell transplants (HSCTs), have been performed since the late 1950s. With over 50 years to perfect the procedure, it has become an accepted standard of care for a number of diseases. The National Bone Marrow Transplant Link has a long list of examples on its website to demonstrate how much progress there has been in the field.
Nevertheless, there is always room for improvement. As discussed above, cord blood has the opportunity to be a successful source of stem cells for transplants, but the available quantities are too small for adult use. Cord blood (and HSC) expansion has been an active area of research for many years in Canada – the Stem Cell Network has supported one of the most promising lines of investigation and, in partnership with CCRM, technologies are now being developed to grow HSCs ex vivo while still retaining their stem cell properties. More on that in the future.
For now, many thousands of people have benefitted from hematopoietic stem cell transplantation – a 2006 global study says a total of 50,417 have taken place – and families around the world, like mine, are grateful that this stem cell therapy is so successful.