Blood ties Joyce Kam, Tuesday, December 15, 2009

Warisara Sainanyen can hardly wait for school to start in two months' time. That's not to say the prospect doesn't scare her like it does other seven-year- olds, but it wasn't so long ago when Warisara thought normal school was out because she had thalassemia, a life- threatening blood disease that causes anemia. That was before an umbilical cord blood transplant performed three months ago. Before then the Thai girl needed a blood transfusion every month since being diagnosed with the genetically transmitted disease when she was just 10 months old. The transplant was possible after Hong Kong private cord-blood bank identified a matching sample from its public donation pool and gave her a free operation in Bangkok. We almost lost hope, but now my daughter is recovering well, Warisara's mother said.

Cord blood is a rich source of stem cells, which can be used to treat more than 80 blood-related diseases such as leukemia and sickle-cell anemia. Researchers around the world have also experimented with using patients own cord blood stem cells Two weeks ago, Georgia Conn, two, was infused with her own cord blood stem cells in Singapore to treat cerebral palsy, an incurable brain injury that affects her body movements and muscle coordination. She was injured at birth. Since the infusion, we noticed that she is more vocal and has a renewed enthusiasm for exercise. She is a lot happier and more comfortable at her regular physiotherapy and occupational therapy sessions. We are heartened with her progress, said her father, Michael Conn, who had the foresight to store his daughters cord blood with a Singapore-based bank, at birth. Cord blood must be stored in liquid nitrogen at minus 196 degrees Celsius in cryogenic tanks.

The success rates of cord blood and bone marrow transplants are similar, falling in the region of 70 percent. But bone marrow transplants involve more risk of complications as the extracted stem cells are more sensitive. The stem cells in cord blood are more naive, or tolerant, than those in our bone marrow so matching doesn't need to be so strict. There's also a lower risk of graft-versus-host disease, a complication that causes the body to attack the transplanted stem cells, said pediatrician Chik Ki-wai. Last year, 40 percent of children worldwide received cord blood as part of stem cell transplants from people other than their family members.

To increase cord blood's availability, researchers at Chinese University of Hong Kong have come up with a way to infuse two units of unrelated cord blood to enhance the chance of engraftment. The three-year program, started in 2006, showed that improvements in patients with acute leukemia who were transplanted with two units of cord blood from unrelated sources are comparable to those in bone marrow transplants. The results, revealed last month, is expected to cut down on the long search time for a suitable bone marrow donor and help more patients to benefit from umbilical cord blood transplants.