IMAGINE the following festive scene. A couple sits in the family room by the Christmas tree, the woman visibly pregnant. A fire roars in the hearth. The man pulls out a large envelope with a silver bow and hands it to his partner. Smiling with expectation, she tears it open to find an embossed certificate. 鈥淢erry Christmas,鈥� the certificate proclaims. 鈥淩edeem this gift for 25 years of cold storage for your baby鈥檚 umbilical cord blood.鈥� 鈥淥h honey,鈥� she exclaims, 鈥測ou shouldn鈥檛 have!鈥�
One company, Smart Cells International, has sold dozens of Christmas certificates like this to parents and grandparents of unborn babies. Their pitch is that stem cells in cord blood already cure diseases, and in 25 years鈥� time they will cure many more. So what better gift for your family than to freeze a few millilitres of blood and have them preserved in liquid nitrogen as insurance against illness or injury? Some cord blood companies tell parents they can buy peace of mind for an initial fee of a few thousand dollars and yearly storage charges of hundreds more. But how much peace of mind?
If the couple already has a child with a life-threatening blood cancer, then banking the cord blood of a healthy newborn sibling is a fine idea, because that blood could save the older child鈥檚 life. The patient is given radiotherapy, which destroys the cancer along with stem cells in the bone marrow. The healthy blood is then transfused, and the cord blood stem cells travel to the bone marrow, where they take up residence and start to churn out billions of blood cells.
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But blood cancers are relatively rare. The bigger promise pivots on the supposed power of cord blood to cure common illnesses such as diabetes, heart disease and Alzheimer鈥檚. If you believe the advertisements, stem cells will someday cure all of these, and may even be used to grow new body parts that are a perfect genetic match for the recipient.
Scientists working at the cutting edge of stem-cell research paint a different picture. Cord stem cells are scarce, and therefore not useful for most adults, who need large numbers of cells for transplants. Some assert that cord stem cells are powerful because they ignore their bloodline heritage and change into a multiplicity of cell types, including heart muscle and brain tissue. But this is hotly contested, and researchers are slugging it out experimentally, testing whether cord stem cells are as potent as the more optimistic scientists and cord blood banking companies claim.
Cord blood certainly has fascinating properties. The stem cells derived from it are immunologically naive: they have not learned the signature of 鈥渟elf鈥� that is so critical to immune rejection. This means they work for a wide range of patients, and several units from different donors can be mixed for adult transplants. Grafts of cord stem cells 鈥渢ake鈥� readily, more so than their bone marrow-derived brethren. Earlier this year, in fact, University of Minnesota researchers reported transplant success in adults using as little as two units of cord blood from unrelated donors.
鈥淧ublic banks would greatly increase the likelihood that a sick child would benefit鈥�
But because the stem cells are carried in blood, the donor and recipient have to be quite closely tissue-matched. Establishing cord blood banks could help: the more units are available, the better the chances that a match will be found for a needy patient. That only partly solves the problem, as once a unit is taken off the shelf it will take an average of 60,000 collections from donors to replace it with an identical match. But what if it were possible to multiply the stem cells in a unit of cord blood 10 or even 20 times? Those cells could then be used for research purposes, to treat adults, and even for multiple rounds of therapy. Best of all, there would be enough cells left over to put back on the shelf.
Using the hormones known as cytokines, it is already possible to 鈥渆xpand鈥� populations of stem cells to produce large numbers of new cells that appear to have the molecular signature of the original stem cells. But appearances can be deceptive. In a recent nationwide clinical trial in which terminally ill cancer patients were treated with one expanded and one normal unit of blood, none of the expanded cells successfully grafted. Similar findings have been reported at transplantation meetings.
For-profit cord blood banking is big business, generating over $300 million in revenues for the top three US companies alone. Should families rely on the promise of future cures that many of these companies hold out? For parents of children with certain illnesses or with a family history of cancer, banking can be a wise choice. For others, it might be more beneficial if the spirit of giving took another form. Rather than relying on the speculative prospect of therapies for their own offspring, they could donate blood to public banks. That would greatly increase the likelihood that a desperately sick child or adult would benefit from it.
