Before talking about the advantages and disadvantages of stem cells from cord blood versus other sources, it's important to first understand the transplant process itself, and the challenge of finding the best possible genetic matches for patients.

In the two weeks before a conventional transplant, patients typically are given high doses of chemotherapy and radiation therapy causing cell counts to drop dramatically.

On the day of the actual transplant, stem cells are injected intravenously, and find their way to the bone marrow. If successful, over the next month, the hematopoietic stem cells will rebuild a new immune system.

While a range of factors affect the success of the transplant, the relationship of the donor to the recipient - which closely reflects the degree of HLA matching is one of the most important. The closer the genetic match, the less chance there is of the graft being rejected and the immune cells of the graft attacking the recipient - known as graft vs. host disease. But a good match is hard to find.

Stem cell transplants fall into two main categories:

• An allogeneic transplant involves taking cells from one person and transplanting them into another person.
• In autologous transplants, the patient is the source of his or her own stem cells for transplant.

For allogeneic transplants, family members offer the best likelihood of success, but even among family members there are challenges. In fact only one third of patients requiring a hematopoietic stem cell transplant have a compatible family donor. Of those seeking a match through the HSC registry, many will fail, creating a major unmet medical need for better transplant sources.

There are different options available for hematopoietic stem cell harvesting.

HSC stem cells come from bone marrow. But harvesting the stem cells is costly and painful. General anesthesia is required. And finding a good match is difficult. About 9,000 patients a year die in the United States waiting for a bone marrow match. About one third of them children.

Peripheral blood has become more popular than bone marrow. The procedure requires growth factor administration to the donor prior to harvest in order to move some of the stem cells from the marrow to the peripheral blood. The procedure takes about three to six hours, and often has to be repeated. In addition, peripheral blood has the same limitations in finding a match as bone marrow.

Cord blood, which has typically been discarded as medical waste, provides an alternative source of hematopoietic stem cells. With cord blood, the degree of HLA mismatching that can be tolerated is greater than with bone marrow or perpheral blood.

Stored cord blood is readily available to family members should the need arise - without having to wait for registries to find a match. The process is painless, less expensive than other procedures, and there's reduced risk of graft vs. host disease.

It's important to note, however, that the time to engraftment and the ability to treat adults are both cell dose dependent.Overall survival rates with cord blood versus bone marrow transplants are about equal.

Families have two ways to preserve cord blood. Saving the cord blood specifically for family use. Or donation to a public bank. While ViaCord believes both models should be supported, the medical literature suggests there are advantages to family banking as we can see from the proven results being achieved today.