Doctors in the Irish Republic feared that Bridget Connors, born with no natural immune system, would die within her first year of life. Her parents transferred her to a hospital in Newcastle upon Tyne, England, for a pioneering treatment which uses blood taken at birth from umbilical cords and then cryo-preserved in a controlled rate freezer before storage in liquid nitrogen. The transplant has meant Bridget has been able to leave a sterile “bubble” in which she lived for more than two months to protect her from infection. The first indications that something was wrong occurred when Bridget developed a rash after coming home from hospital. A series of medical tests discovered that she had a defective immune system, making a bone marrow transplant the only likely route to recovery. Her parents were put in touch with the immunodeficiency unit at Newcastle General Hospital, one of only two hospitals in the country that has a bubble unit specifically for children who cannot fight infection.
There a team, directed by Andrew Cant, found a perfect umbilical blood match for Bridget within five days, from a woman who had given birth in 1998. Cord blood has a number of advantages over bone marrow. The product is available ‘off the shelf’ as it has been microbiologically tested and tissue typed to low resolution. This means that suitable cord donors can be selected very quickly. The DNA from the cord, previously extracted and stored so high resolution tissue typing, which is necessary for the best transplants, can be performed immediately. From search to request to high resolution typing, it can take a matter of only a few days compared to the six months possible for bone marrow. The Blood Bank was set up in Newcastle two years ago in an attempt to find new treatments for childhood cancer. Blood from the umbilical cord is rich in white blood cells and can be used as an alternative to a bone marrow transplant for children with no immune system. Dr. Cant said: “The time scale involved in this case is absolutely unheard of. We had warned Bridget’s parents that she could be in the sterile bubble unit for months before a donor could be found.”
In the procedure, after birth the umbilical cord is clamped and a needle inserted close to the placenta so the blood can be drained off and collected. Cord blood contains immature stem cells, which is a possible explanation as to why cord blood donors do not need to be quite so well matched to recipients as do bone marrow donors. Some clinicians manage with only half the transplant related antigens matching - although five out of six matching at high resolution are normally preferred. In practice this means that the probability and severity of rejection are lower with cord blood transplants.
About 90 millilitres of blood is collected from a donor at birth and after the blood has been screened, it is taken to a blood transfusion centre. In this case at Newcastle it was then controlled rate frozen in a Planer machine. The company, based at Sunbury near London’s Heathrow Airport, is a world leader in cryo-preservation equipments. The sample can be then be stored for up twenty years in normal liquid nitrogen cryogenic containers. Because the blood is stored frozen it can be retrieved, thawed and washed in a matter of hours resulting in a product that is probably purer than bone marrow and also occupies a smaller volume. This can be transfused in about an hour and no special filters are needed. The controlled rate freezing process is central to the quality of the stored cells as it can be set to provide the optimum freezing curve for the stem cells in the cord blood and it also produces a record of this process for control and Q.A.
The potential for cord blood as an alternative to bone marrow has been discovered only recently. There are 500 donations of umbilical cord blood in Newcastle and doctors are hoping to store more than 1,000 during the next year.