Cord blood - the power cord of stem cell research
Tabitha Ellem is one of over 600 children who have been treated by umbilical cord blood and bone marrow transplants at the Sydney Children's Hospital at Randwick. When Tabitha was two, she was diagnosed with Hurler's Syndrome - a very rare metabolic storage disorder where sufferers lack an important enzyme which results in damage to soft tissue cells in the heart, brain, liver, eyes and bones. Without a transplant, most will die by the age of 10. Tabitha's diseased white blood cells with the missing enzyme were replaced with new healthy cells from a cord blood transplant, preventing further damage being done.
What are cord blood stem cells?
For those who, like me, don't know much about them, cord blood stem cells are one of three types of stem cells. Stem cells are unspecialised cells that give rise to specialised cells in the body. They can replace diseased or bad cells with new and healthy ones as they have great potential to treat diseases and find cures for them.
Scientists are constantly trying to find new sources of stem cells. 'The discovery of stem cells was one of the most amazing breakthroughs in the history of medicine,' explains Dr Colin McGuckin, the director of Cell Therapy Research Institute in Lyon, France. 'But the real promise of stem cells is to help repair your own body, something no-one could ever have imagined only 20 years ago. Today we see new treatments appearing every year. Stem cells are not only about giving a cure, but also about giving a better quality of life.'
Types of stem cells
Stem cells fall into three categories:
- Embryonic stem cells These cells are derived from very young embryos and their potentially unlimited capacity to transform into any of the estimated 210 cell types found in the body makes them the most "valuable" cell type. They can therefore be used for almost anything. There is, however, controversy around them - extraction of embryonic stem cells destroys the embryo and is therefore shunned by opponents of abortion.
- Cord blood stem cells Cord blood is the blood that remains in the umbilical cord and placenta after the cord is cut in birth. It's a valuable source of stem cells, which are genetically unique to the baby and the babies' family. Although embryonic stem cells are more versatile, cord blood cells have the potential to form into many kinds of cells. Cord blood stem cells are eight to 10 times more proliferative than adult stem cells.
- Adult stem cells Adult stem cells are undifferentiated cells found in tissues or organs. They can produce more stem cells and also give rise to specialised cell types of the tissue or organ they are located in. A number of adult stem cell therapies already exist; particularly bone marrow transplants that are used to treat leukaemia. However they are believed to be more limited in the type of cells they can generate when compared to embryonic and cord blood stem cells.
Cord blood cells are a powerful resource, as Dr McGuckin and Nicolas Forraz wrote in their chapter Cord Blood Stem Cells - Potentials and Realities for the book, Advances in Tissue Engineering (Imperial College Press, $304.65) edited by Julia Polak, Sakis Mantalaris and Sian E Harding: With approximately 130 million babies born worldwide every year, umbilical cord blood represents perhaps the largest potential source of stem cells for regenerative medicine. Cord blood stem cells are used clinically, mostly to support patients suffering from haematological and immunological diseases but they also provide emerging therapeutic solutions for limited cases of type-1 diabetes or infant cerebral injuries. Medical researchers are therefore constantly working on cures and trying to find more and more uses for this powerful source.
In a 2007 study, researchers reported that they engineered adult stem cells derived from cord blood to produce insulin. This finding may someday help cure type-1 diabetes by allowing people to grow their own insulin-producing cells. Other recent research used cord blood cells to grow heart valves. According to the March of Dimes - a long-established US health charity whose mission is to improve the health of babies - heart defects are among the most common birth defects and leading cause of birth-related deaths. When these valves are faulty they need to be replaced. Although these valves are lifesaving, multiple surgeries are required to replace valves as children grow up. German scientists are hoping that within five to seven years they will be able to provide new heart valves that grow as the child develops, using stem cells collected from the child's own cord blood.
One of the most exciting studies came about in 2005 when a team led by British and American researchers uncovered a number of stem cells in umbilical cord blood, with characteristics similar to embryonic stem cells. These cells, named cord-blood-derived embryonic-like stem cells (CBEs) are incredibly significant. They may enable researchers and scientists to harness the potential of embryonic stem cells without the ethical objections. 'Our work showed, categorically, that the moment of birth is critical and a "once in a lifetime" opportunity to save stem cells for later use, perhaps for your child or even someone else,' explains Dr McGuckin, who co-led the study with Dr Forraz.
Cord blood storage
Another reason why this finding is significant is because umbilical cord blood can be saved and stored without the ethical issues that face embryonic stem cell use. 'I believe that every large metropolitan city in the world should have a cord blood bank, with all of them linked by computer across the world. Only by doing this, will we be able to protect the health of our populations in the future,' explains Dr McGuckin.
Ryan Lilburne, from Perth, who suffered a blood disorder that put him at risk of aggressive leukaemia was lucky enough to have cord blood stem cells donated from France last year after no suitable bone marrow donor was found. In April, the 15-year-old was given days to live but, thanks to cord blood being made available, spent Christmas at home with his family. While he is not out of the woods and still tires easily, for the first time he can eat what he wants, sleep over at friends' homes and will return to full-time school in Year 11 next year with the aim of becoming an electrician, wrote Cathy O'Leary in The West Australian (December 2008).
Private storage can be seen as a type of insurance. 'Although the probability of a child needing to use it in early childhood is low, there is great potential in these cells. Parents who store their baby's cord blood will be able to tap into the future benefits of stem cell research, although research already supports the use of stem cells in the treatment of heart disease, and early results from trials in the US suggest a role in treating children with cerebral palsy,' says Dr Roisin Deane, Marketing Manager of Cryosite.
"We decided this was the best way to spend our baby bonus as my husband earns a good wage and we have everything we need for bub," writes Jen on the Bub Hub forum as part of her story to share with others. "We have home insurance in case something goes wrong, we hope we never have to use it but if we do it is there. The same with the stem cells. It's an insurance policy that we hope we never have to use but if we do it's there."