What is umbilical cord stem cell banking

Umbilical cord as a source of valuable stem cells

The umbilical cord blood contains stem cells that can serve as a reserve for new cells in some diseases. That is why they can be frozen after the baby is born. But the promises exceed reality.

When a child is born, parents now have the option of freezing the umbilical cord blood of their offspring. The blood contains so-called adult stem cells, a kind of "mother cells" that can form different cell types. Although these stem cells are not infinitely versatile like embryonic stem cells, they too have great therapeutic potential. They are already being used successfully for certain rare diseases, such as severe leukemia.

Private or public bank

A major advantage of umbilical cord stem cells is that, in contrast to embryonic stem cells, for which embryos have to be destroyed to obtain them, they can be isolated from a waste product to a certain extent. In order not to lose these valuable cells, umbilical cord blood banks (NSB banks) have been established since the mid-1990s, which freeze the umbilical cord blood of newborns in liquid nitrogen. The more than one hundred public NSB banks that have been created since then store the acquired units free of charge and make them available to all patients worldwide - analogous to the internationally accessible registers of bone marrow donors. In contrast, private NSB banks store the blood exclusively for the donating child and his / her family - as a kind of private life insurance, as the providers of this service like to emphasize. A contract for 20 to 25 years is available from around CHF 3,000.

While “public banking”, i.e. the non-profit storage of umbilical cord blood, met with unanimous approval, “private banking” was almost unanimously rejected by medical associations and ethics committees. The probability of ever benefiting from one's own umbilical cord blood is too low - according to estimates, it is a fraction of a per mille. In addition, the providers aroused hopes and fears in the parents that lacked a scientific basis. For example, promising new treatment methods for cancer, Alzheimer's or Parkinson's, which have only been researched in animals so far, are being advertised.

Some experts go so far as to call for a legal ban on commercial NSB banks, as is already in place in Italy and some other countries. Nevertheless, a growing number of parents-to-be are opting for “private banking”, so that today a large part of the probably around one million NSB units collected around the world are stored at commercial banks. This triumph of private banking is also due to the fact that private donations are possible in almost every hospital in Switzerland and other western countries. Because commercial providers ensure comprehensive logistics. In contrast, donations to the public NSB banks, which operate with limited financial resources, are only possible at their local clinics; in Switzerland currently in Basel, Geneva, Bern, Liestal and Lugano.

In order to bridge the conflicting interests of “public” and “private banking”, a combined solution is being tried out in many places today. Parents store their child's UCB blood on a private basis, but make the information about their tissue type publicly available. Should a patient, anywhere in the world, need a donation with this type of tissue, parents can release their child's umbilical cord blood. Hybrid banks of this kind exist today in England and Germany, for example. According to Daniel Surbek, head of the university clinic for gynecology there, this concept is also currently being examined in Bern.

Own cells rarely used

However, the established applications of UCB stem cells have so far been limited to serious diseases of the hematopoietic system such as blood cancer and bone marrow defects as well as some rare, mostly hereditary immune, cancer and metabolic ailments - i.e. diseases traditionally caused by transplantation of stem cells the bone marrow to be treated. The rise of UCB transplants began in 1988 when the doctor Eliane Gluckmann in Paris injected UCB stem cells into a five-year-old boy with a life-threatening form of anemia from his sister, thus saving his life. Since then, around 20,000 UCB transplants have been performed worldwide. Only in very few cases - by the end of 2009 in just 206 patients worldwide - were own stem cells transplanted from private banks.

While the private storage of umbilical cord blood may be useful in special cases - for example for people from ethnic minorities for whom suitable donors are difficult to find - it is, however, clearly not advisable to transplant UCB stem cells for some diseases. In the case of genetic diseases such as thalassemia (Mediterranean anemia), the cells of the umbilical cord also carry the genetic defect, so that a transplant of these cells does not promise a cure. Even with leukemia, which by far most frequently requires a stem cell transplant, there is a certain risk, especially in small children, that the predisposition to the disease will be transplanted with their own stem cells, explains Urs Schanz, transplant specialist at the University Hospital Zurich.

But even in the case of foreign transplants, which is now the norm, UCB stem cells offer undisputed advantages over stem cells from the bone marrow or adult blood. Due to their "youthful" properties, they cause less rejection reactions, so that the tissue properties of the donor and recipient do not have to match exactly and the spectrum of possible donors is thus greatly expanded. Above all, however, UCB donations are immediately available when needed, while registered bone marrow donors must first be asked to have a bone marrow removed and donors of peripheral blood stem cells still have to undergo treatment. The associated delays can be the life and death of the recipient.

Propagation of stem cells

However, umbilical cord blood has the disadvantage of only containing a limited number of stem cells, so that transplantation of a single unit (from just one umbilical cord) is often only successful in children. For several years this problem has been solved by transplanting two UCB units at the same time; It is therefore more and more common for adults to benefit from an UCB transplant. The multiplication of UCB stem cells in the laboratory promises an additional improvement. It has already been possible to increase the number of cells many times over with the help of biochemical tricks. In January, doctors at the University of Washington in Seattle reported the transplantation of such artificially propagated stem cells. Ten adult patients with acute leukemia were simultaneously injected with an external donation with multiplied stem cells and an untreated UCB unit, also from external donors. In this way, the restoration of the previously destroyed bone marrow could be accelerated considerably.

Studies on cell cultures and in animals provide evidence that UCB stem cells may be able to stimulate the body to heal itself. This hypothesis is now being tested in individual clinical pilot studies. At the University of Florida in Gainesville, for example, a study is underway in which 23 children with type 1 diabetes are treated with their own cord blood in the hope of replacing the insulin-producing cells in the pancreas that have been destroyed by the body's immune system. Even if the treatment proves to be well tolerated according to an interim report, a statistically significant benefit has not yet been proven.

Another study, conducted at Duke University in North Carolina, is examining transplantation of own UCB cells in children with cerebral palsy and other severe brain damage. In 2 of the more than 100 children treated so far, their parents reported positive effects that were widely reported in the press. But Joanne Kurtzberg, the head of the as yet unpublished study, warns against exaggerated expectations.

To this day, the hope of treating patients with tissue grown from their own UCB cells has not been fulfilled. In addition to blood stem cells, which - as mentioned above - can be used to restore the blood-forming system in leukemia patients, umbilical cord blood also contains stem cells that form other cell types such as muscle or cartilage cells. However, the number of these stem cells is so low that not enough cells can be obtained from frozen blood for tissue cultivation.

However, living tissue has already been produced in the laboratory from fresh umbilical cord blood. Scientists at Zurich University Hospital, for example, breed heart valves; in the hope of one day using them as prostheses for newborns with a prenatal heart defect. The stem cells are to be obtained from the unborn child by puncturing the umbilical cord. Since these heart valves could grow with the child, they would not have to be replaced every few years, unlike the prostheses available today. «Tissue engineering» projects of this kind are promising, but not yet fully developed. In the opinion of many experts, therefore, storing umbilical cord blood with a view to such applications is not yet an urgent matter.