| Hematopoietic stem cell transplantation refers to a group of procedures which collect stem cells from an individual donor and administers them to an individual with defective bone marrow or immune system. Stem cells are immature cells that are produced in the bone marrow and circulate in small concentrations in the blood. Stem cells are the precursor to white blood cells for immune function, oxygen-carrying red blood cells (erythrocytes), and platelets which facilitate clot formation. In the early 1960's the collection of donor stem cells was done exclusively from the donor's bone marrow, hence the procedure was referred to as bone marrow transplant. Over recent years, advances in medicine have allowed for successful collection and transplantation from bone marrow as well as other sources, such as peripheral blood or placental blood. Consequently the procedure is now generally referred to as "stem cell transplantation" or "hematopoietic stem cell transplantation (HSCT)." This term is used universally to describe any transplantation of the stem cells, regardless of the donor source.
Four types of hematopoeitic stem cell transplants exist. These include autologous, in which the individual's own stem cells are removed, processed and then returned to the body. A syngeneic transplant refers to transplants in which the donor is an identical twin of the recipient. These transplants are most desirable since the donor marrow and recipient marrow are perfectly matched thus preventing the complication of post-transplant rejection. When the donor is a sibling or parent of the recipient, the transplant is referred to as allogenic. Finally, unrelated donor transplants are those transplants in which the donors are unrelated and have no genetic likeness to the recipient. These donors often require extensive screening, genetic typing and blood typing prior to the transplant procedure to ensure the closest match to the recipient.
Hematopoeitic stem cell transplant were originally performed in the late 1960's for the treatment of certain disorders of the bone marrow such as leukemia, aplastic anemia, Hodgkin's disease and multiple myeloma. More recently, this procedure has been used to help restore the immune system in those with immune deficiency disorders and certain individual's with cancer who have undergone intense chemotherapy treatment. |
Source: Medical Disability Advisor
| Hematopoeitic stem cell transplantation (HSCT) can replace diseased or poorly functioning bone marrow with stem cells, which ultimately develop into normal, mature white blood cells (leukocytes), red blood cells (erythrocytes) and platelets. An HSCT may be done to bolster the immune system in those with immune deficiency disorders or those with immune system compromise following intensive chemotherapy or radiation therapy.
Disorders treated with stem cell transplantation include leukemia, lymphomas, multiple myeloma, solid tumors (especially breast tumors), and a range of blood disorders including thalassemia major, sickle cell anemia, and aplastic anemia. Other conditions that may be treated with HSCT include neuroblastoma, testicular cancer, malignant melanoma, soft tissue sarcoma, small cell lung cancer, colon cancer, ovarian or uterine cancer, granulocyte disorders, platelet disorders and metabolic storage diseases. Syngeneic and allogeneic transplantation have been most effective in treating acute nonlymphocytic leukemia, severe aplastic anemia, and chronic myelogenous leukemia. Autologous transplants are most effective in treating Hodgkin and non-Hodgkin lymphomas. |
Source: Medical Disability Advisor
| The first step of stem cell transplant is to establish the closest match between donor and recipient cells. Once a potential donor has been identified, the candidate must first undergo extensive blood testing to confirm the absence of disease and to verify the suitability of the match. Clearly, a donor who is an identical twin of the recipient (syngeneic transplants) is the most ideal match. Harvesting from the recipient's sibling (allogeneic transplant) provides the next best match. Harvesting from unrelated donors (unrelated donor transplant) is possible, but requires lengthy blood testing that may take up to 4 months to find a suitable match. Even with careful matching, unrelated donor transplants have higher rates of complications.
Sources of hematopoeitic stem cells include the bone marrow, the peripheral blood and umbilical blood. To harvest stem cells from the bone marrow, the donor receives general anesthetic, a needle is inserted in the marrow of the iliac crest (hip bone) and the marrow is withdrawn.
Hematopoietic stem cells can also be harvested from the peripheral blood for either autologus transplants or allogeneic transplants. A hematopoietic growth factor is administered to the donor (or recipient in the case of autologus transplant) to trigger the release of stem cells from the bone marrow to the bloodstream. Blood, rich in stem cells is then collected, processed and later administered to the recipient when needed. This source is often preferred over the bone marrow collection because it does not require anesthesia and its associated risks.
Stem cells may also be collected from the umbilical cord at the time of delivery, processed and stored for future use in allogeneic transplants or unrelated donor transplants. The cord blood is rich in stem cells and because the immune system is immature at birth this source has fewer post transplant rejection than other sources. One limitation is that only a small volume may be collected from the umbilical cord.
After a suitable donor is selected and stem cells are harvested, the recipient must go through a preparative regime that suppresses the recipient's immune system enough to prevent rejection and to eliminate the underlying disease. This may involve the administration of maximally tolerated doses of chemotherapy drugs and possibly radiation therapy. The preparative regimen is associated with significant side effects and complications. To minimize the side effects and complications, a new regimen called "sub-ablative" or "mini" transplants is being used in some cases, which uses lower doses of drugs together with radiation to provide adequate immune suppression for successful transplantation.
Once the recipient has completed the preparative regimen, they receive an intravenous infusion of the stem cells (without the use of a blood filter). Hospitalization and close monitoring for complications of transplantation such as graft rejection, infection, etc. is needed for several days to weeks. Antibiotics and transfusions may be administered during this time to help prevent and fight infection. Blood elements will need replacing if anemia, leukopenia, or thrombocytopenia occur before the bone marrow "takes" (engraftment). |
Source: Medical Disability Advisor
| An uneventful recovery is expected for bone marrow and peripheral blood donor. It will take about 4 weeks for the body to replace the amount of bone marrow donated.
Individuals receiving bone marrow transplant for the treatment of aplastic anemia, early chronic myeloid leukemia, or thalassemia without liver involvement may have disease-free survival rates of approximately 90%. However, those receiving transplants for advanced malignancy have a much poorer outcome. These individuals often experience toxicities secondary to the aggressive treatment regimens and tend to have high relapse rates. As a consequence, this group may have only a 5-year-survival rate of 5% to 30% (Brenner 988). |
Source: Medical Disability Advisor
| Several complications may arise prior to transplant due to the necessary intensive preparative treatment of chemotherapy and radiation therapy. The intensity of this pretreatment regimen varies based on the type of donor and the underlying condition of the recipient. These preparative regimens, particularly the very intense regimens, often result in a number of adverse effects that may be lethal. The most common life-threatening pretreatment complication is hepatic veno-occlusive disease, a disorder which literally chokes the circulation to the liver causing liver dysfunction and multiple organ failure in 20% of affected individuals. Another pretreatment complication is hemorrhagic cystitis (bleeding from the bladder) which occurs in 5% to 50% of those who had preparatory treatment with a high-dose chemotherapeutic drug called cyclophosphamide. The hemorrhagic cystitis usually resolves, but may cause urinary tract scarring and dysfunction.
Following transplant, there are two possible transplant-related complications. Graft-versus-host-disease (GVHD) occurs in approximately 50% of individuals who have undergone allogeneic bone marrow transplant. The donor immune-system cells attack the cells of the recipient, because they appear foreign (not genetically matched). This attack may cause severe immune system and organ system dysfunction in the transplant recipient. The second complication is graft rejection, in which the donor cells fail to regenerate as expected. This complication occurs in approximately 1% to 2% of sibling-matched allografts and significantly more frequently in unrelated donor transplants (Efiom-Ekaha). Other complications associated with a bone marrow transplant procedure include bleeding, post-transplant immunodeficiency, hypothyroidism, respiratory arrest, renal failure, pneumonia, allergic reactions, fever, anaphylactic shock, air embolism, and development of a second malignancy. |
Source: Medical Disability Advisor
| The individual will not be able to return to regular activities or full-time work for 6 months or more from the day of the transplant. Individual may initially be restricted to work on a part-time basis with a gradual transition to full-time as strength and endurance increase. During this time, visits to a hospital or clinic as an outpatient may be needed several times a week for monitoring, blood transfusions, and administration of other drugs, as needed. Work accommodations include time away from work for clinical and medical appointments and extended rest periods in a quiet place.
The successful transplant recipient will eventually be strong enough to resume a normal routine and lead a productive, healthy life. |
Source: Medical Disability Advisor
| Brenner, Malcolm J. "Bone Marrow ." Cecil Textbook of Medicine (2000): 987-991. MD Consult. Elsevier, Inc. 22 Sep. 2004 <http://home.mdconsult.com/das/book/40990599-2/view/882?sid=284946628 >.Efiom-Ekaha, D., et al. "Hematopoeitic Stem Cell Transplantation." eMedicine. Eds. Karen Seiter, et al. 13 Oct. 2004. Medscape. 22 Sep. 2004 <http://emedicine.com/med/topic3387.htm>. |
Source: Medical Disability Advisor
| Feedback |
| Send us comments, suggestions, corrections, or anything you would like us to hear. If you are not logged in, you must
include your email address, in order for us to respond. We cannot, unfortunately, respond to every comment.
If you are seeking medical advice, please contact your physician. Thank you! |
Send this comment to:
Sales
Customer Support
Content Development
|
|
| |
|
|
|
|
|
This publication is designed to provide accurate and authoritative information in
regard to the subject matter covered. It is published with the understanding that
the author, editors, and publisher are not engaged in rendering medical, legal,
accounting or other professional service. If medical, legal, or other expert assistance
is required, the service of a competent professional should be sought. We are unable to respond to requests for advice.
Any Sales inquiries should include an email address or other means of
communication.
|