Over the last 30 years, bone mar-
row transplants have saved
thousands of lives of people af-
flicted with a wide range of blood disorders such as leukemia and aplastic anemia as well as selected immune system diseases and genetic disorders. When it was discovered in the 1970s that the umbilical cord blood contained the same kind of stem as that in bone marrow with concentrations nearly 10 times greater than that found in bone marrow. Because stem cells were already being used successfully to treat patients with life-threatening blood diseases, researchers believed they could also use stem cells from cord blood to save patients.
The first human umbilical cord blood stem cell transplant was achieved in 1988 in a five-year-old boy suffering from Fanconi’s anemia. Ten years later, the boy is still alive and seems cured. Because of this and other successful transplants, doctors and medical researchers began to collect, freeze and store cord blood units.
To understand why we bank cord blood, we need to understand the basic question.
Stem cells are actually primitive cells that give rise to other types of cells. There are several kinds of stem cells. When a sperm fertilizes an egg and forms an embryo, each of the cells comprising the embryo is an embryonic stem cell. Each of these cells are totipotent because they contain all the genetic information needed to create all the cells of the body plus the placenta which nourishes the human embryo. These are the cells used for cloning. Human cells have this capacity only during the first few divisions of a fertilized egg or embryo. After 3-4 divisions of totipotent cells, there follows a series of stages in which they become increasingly specialized. The embryo becomes a blastocyst where the inner cell mass becomes a source of pluripotent stem cells, which are highly versatile and can give rise to any cell type except the cells of the placenta. After the eighth week, the blastocyst is called a fetus which is also a source of pluripotent stem cells. At the next stage, cells become multipotent, meaning they can give rise to several other cell types, but those types are limited in number. An example of multipotent cells is hematopoetic cells – blood stem cells that can develop into several types of blood cells, but were believed not to be able to develop into brain cells. These may be obtained from the bone marrow, and from umbilical cord blood.
Scientists always believed that differentiated cells cannot be altered to behave in any other way other than that they were naturally committed for. But in recent stem cell experiments, they have discovered that given the correct stimulus, blood stem cells can be made to behave like neurons, or brain cell.
Furthermore, it was recently discovered that some stem cells also occur in the bodies of adults rather than exclusively in embryos. Many kinds of multipotent stem cells have been discovered in adults and scientists believe that many more will be discovered, although at the moment, it seems to be less versatile. The problem with embryonic stem cells is the ethical issue behind needing to destroy the embryo in order to produce the stem cells.
| Current Applications Of Stem Cell Therapy |
Science has been finding ways to identify young regenerating cells which can be used to replace damaged or dead ones in diseased organs. This therapy is similar to the process of organ transplant, but you transplant cells instead of organs. Stem cell therapy is applicable for the following disorders:
Acute Lymphocytic Leukemia (ALL), Acute Myolocytic Leukemia (AML), Juvenile Myelomonocytic Leukemia, Acute Undifferentiated Leukemia, Chronic Myelomonocytic Leukemia, Advanced Chronic Myelocytic Leukemia (chronic phase one year after dx), and in Myelodysplastic Syndrome.
| Paroxysmal Nocturnal Hemogobinuria Advanced Lymphoma Anemia |
Severe Aplastic Anemia and Fanconi’s Anemia
| Inborn Errors Of Metabolism |
Hurler’s Syndrome, Maroteux-Lamy Syndrome and Leukodystrophies,
Wiskott Aldrich Syndrome and Higashi Syndrome
| Thrombocytopenia Justification For Banking Cord Blood |
Researches have found that cord blood, which we usually throw away after delivery along with the placenta, is actually a rich source of stem cells which can produce other types of healthy blood cells — red, white and platelets which can replace diseased ones after they are destroyed. In the event that your child or a sibling or even a parent, develops some types of cancer or blood disorders at some point, the stored sample provides a perfect match of stem cells for stem cell therapy of the child and a reasonable chance of a match for the sibling or parent, better than that sourced from any non-related stranger.
Harvesting umbilical cord blood poses no risk to mother or child whereas a bone marrow donor must undergo anesthesia and is exposed to the risk of infection. Umbilical cord blood can be stored in cryogenic freezers, ready for use as soon as it is needed whereas bone marrow transplant requires donor to be around and the process of contacting and testing bone marrow donors takes weeks. Umbilical cord blood stem cell therapy is therefore less costly. Furthermore, cord blood is rarely contaminated by viruses often found in marrow such as cytomegalovirus (CMV) and Epstein-Barr virus. More importantly, because stem cells in cord blood are more primitive than those in bone marrow, they carry a much lower incidence of rejection of the transplanted stem cells by the recipient, a phenomenon called graft versus host disease (GVHD). This makes it possible to perform transplants with less than perfect matches of type.
| Technique Of Cord Blood Banking |
During a normal delivery or a Cesarean section, blood from the umbilical vein can be collected when the child is delivered and the umbilical cord is clamped and cut. Extracting stem cells from the umbilical cord is painless and won’t harm the mother or baby since it is obtained from the cord attached to the placenta which we normally just discard. They are placed in containers ready to be air-flown to the country where the cord blood bank is. (For now, there is no laboratory in the Philippines that is equipped for this service so we have to send the blood to foreign cord banks). The stem cells are systematically frozen at minus one degree at a time until they reach the optimal temperature of minus 180 degrees C to insure viability of stem cells. These are stored in nitrogen tanks of —180 degrees C available for thawing and transplanting when the need arises.
Several teams are looking into stem cell expansion which looks at how stem cells in a cord blood unit can be stimulated to grow additional cells before infusing them into a patient. Currently, the number of stem cells banked from one baby’s umbilical cord can be used for stem cell therapy of up to an adult weighing about 110 lbs. Bigger than that, it requires a bigger volume of stem cells. If science could find a way to coax the stem cells into replicating themselves in the lab, it could be made available to more than one member of the family as a form of medical insurance.
Researchers have already generated insulin expressing cells from mouse stem cells. It may be possible in the near future to provide a stem-cell based therapy to treat diabetes to replace the constant need for insulin injections.
The knowledge of stem cells has made it possible for scientists to grow skin from a patient’s plucked hair where stem cells are found. These cells can be cultured and is presently being tried clinically as an alternative to surgical grafts used for venous ulcers and burn victims, bypassing the problem of rejection.
| Brain Cell Transplantation |
Potential targets of neural stem cell transplants include stroke, spinal cord injury, and neurodegenarative diseases such as Alzheimer’s and Parkinson’s disease. The first double blind study of fetal cell transplants for Parkinson"s Disease reported survival and release of dopamine from the transplanted cells and functional improvement of clinical symptoms. Over 250 patients have already undergone stem cell transplant for this problem.
The production of cardiac muscle cells would hold tremendous promise for the number one killer: heart disease. Several cases of cardiac muscle cell transplant have already been done for heart attack victims to regenerate the diseased muscle cells and even to save the life of an accident victim whose heart was punctured by a metal rod.
Despite the many challenges to hurdle, most scientists believe that cell therapy will revolutionize medicine. Imagine the future where it may be possible to prolong human life because we can replenish tissues in aging organs. We might even be able to grow our own organs one day for transplantation from our own stem cells, eliminating the danger of organ rejection. There is every reason to hope that this revolutionary new approach will radically change the way we think about diseases, especially the ones we once thought were incurable.
xDr. Rebecca B. Singson is a Fellow of both the Obstetrics and Gynecologic Society and Philippine Society of Cervical Pathology and Colposcopy. Currently, she is holding clinics at Rm. 381, Makati Medical Center, 892-7879; and at Rm. 202-203, Asian Hospital and Medical Center, 771-9204 and 771-9206 or e-mail obmd@surfshop.net.ph.