Stem cell research and therapy, which are fraught with scientific and ethical controversy,1 may seem irrelevant to many practicing family physicians. However, it has been estimated that more than 100 million Americans have conditions that eventually may be treated by stem cells. Family physicians are in a unique position to educate patients about this therapy.
A stem cell is defined as any cell with the capacity to self-renew and differentiate into a more specialized cell. Stem cells have been found in embryos, many adult tissues, and umbilical cord blood. The most common and well-known application of stem cell therapy has been bone marrow transplantation. Since the 1980s, human hematopoietic stem cells have been isolated from bone marrow and used to treat patients with various hematologic malignancies. Bone marrow transplantation also has been used successfully to treat immune deficiencies, hemoglobinopathies, and metabolic diseases.2
Although the attention of the news media has been directed at the controversial and unproven area of embryonic stem cells, a rich and largely unappreciated source of stem cells, umbilical cord blood, has been used to treat more than 75 conditions including cancers, immunodeficiencies, inborn errors of metabolism, bone marrow failure syndromes, heart disease, and some autoimmune conditions. These cells are easily collected with no risk to the donor. Other advantages include a decreased likelihood of causing graft versus host disease, shorter time to transplant, and minimal risk of viral transmission.3 Animal studies are being conducted to test potential applications of stem cells in conditions such as stroke, diabetes, osteoporosis, macular degeneration, and urinary stress incontinence.
The success of stem cell therapy depends on a number of factors, including the genetic compatibility of donor and recipient. Autologous donation is safest, with directed donations from human leukocyte antigen (HLA)-matched family members next in desirability. A number of private cord blood banks have capitalized on this potential treatment by offering to collect, process, and store cord blood at a cost of $1,100 to $1,750 for initial collection and $115 to $125 per year for storage.3,4 However, concerns abound regarding quality control.4 In addition, the chances of a person or family member needing stem cells are low, estimated at 0.05 percent (one in 2,000).3 For many needy patients, the cost of personalized cord blood collection and storage is prohibitive. Because cord blood transplants from unrelated donors may succeed with one or two HLA mismatches,3 at least 13 states have passed legislation promoting public cord blood banking through education of pregnant women or support of cord blood banks. Mothers may donate cord blood after delivery at no charge and are given access to suitable matches if the need ever arises for immediate family members.5,6 Cells became available for treatment or research in greater quantities and at a more reasonable price through such legislation.
In December 2005, Congress passed the Stem Cell Therapeutic and Research Act, which designated $79 million to collect 150,000 units of cord blood from donors of sufficient diversity that 90 percent of Americans who might need stem cells would be able to find a match.7 This cord blood bank will be combined with the National Marrow Donor Program for transplantation (http://www.marrow.org).
Family physicians can play an important role in informing patients of this program and encouraging pregnant patients to donate cord blood. More discoveries are being made about the plasticity of adult stem cells that may lead to future treatments for disease and life-prolonging therapies.