Bone Marrow/Stem Cell Transplantation
- uses
- bone marrow donor registry
- procedure
- risks
- management
- patient education
- online resources
- references
Uses
Hematopoietic stem cell transplantation can be used for:
allogenic
- acute leukemia
- myelodysplastic syndrome
- chronic myelogenous leukemia (CML)
- severe aplastic anemia
- indolent lymphoma
- chronic lymphocytic leukemia
- severe immunodeficiency
- hemoglobinopathies
autologous
- progressive large-cell lymphoma
- progressive Hodgkin's Disease
- multiple myeloma
- relapsed germ cell tumour
Bone Marrow Donor Registry
The International Unrelated Donor Registry has over 7 million people on file. At present, a satisfactory unrelated donor can be found in 80% of white patients, though this number is lower in other ethnic groups.
Procedure
Harvesting
Hematopoietic stem cells are now commonly harvested from peripheral blood following treatment with hematopoietic growth factors (ie, G-CSF). Blood is collected and subjected to leukopheresis to gather cells for transplantation.
Umbilical cord blood can also be used for this purpose.
Conditioning
Patients are subject to high dose chemotherapy (ie cyclophosphamide), often combined with total bosy irradiation, to destroy cancer and suppress the host's immune system. Patients are treated prophylactically to prevent infection and are kept in isolation.
Transplantation
HSC transplantation is a simple procedure involving intravenous infusion over 1-2 hours. Stem cells then 'home' to the bone marrow and re-establish hematopoiesis over the next two weeks.
Engraftment
Engraftment is said to occur when neutrophil counts are consistently above 0.5 x 109/L, and usually takes 10-20 days. Platelet and RBC engraftment usually follows. Patients are supported with blood products until they are ok.
Failure to engraft, or graft failure, occurs in less than 5% of recipients.
Restoration of T- and B-cells may take 12 months or longer, leading to recovered immunological functioning, along with graft-versus-host disease.
Risks
During conditioning, patients suffer from hematologic and non-hematologic toxicity. Infertility is the rule following totoal body irradiation. Oropharyngeal mucositis is especially difficult for patients.
Breaks in the skin, together with neutropenia, lead to risk of infection. All patients receive antifungal and antiviral prophylaxis.
Graft-versus-host disease occurs as donor T cells recogize the host as foreign. GVHD prophylaxis, including a combination of methotrexate and cyclosporine, is commonly used. GVHD risk is increased with HLA mismatch, older age, allosensitization following pregnancy or transfusion, sex mismatch, or other factors.
Treatment-related mortality in the first 12 months in sibling-matched transplantation is 20-30%.
Management
Ongoing complications include organ damage from the conditioning regimen, chronic GVHD, and immunosuppressive drugs. Potential medical complications of long-term immunosuppressive therapy include:
- osteopenia or osteoporosis
- avascular necrosis of the hips, shoulders, or knees
- hypertension
- diabetes mellitus
- hyperlipidemia
- accelaratioed atherosclerosis
- renal insufficiency
- myopathy
- secondary malignancy, ie lymphoma
- depression
- cosmetic changes: obesity, hirsutism, acne, skin striae
Reactivation of latent infections, such as varicella or CMV, are common and can be life-threatening.
- assess for chronic GVHD every 3 months
- complete dental exam every 6 months
- complete annual physical examination
Patient Education
Safe-living practices are important. Food preparation should be meticulous.
Fresh water should be avoided, and sexual activity may need to be modified.
Travel to developing countries is not recommended during the first two years after transplantation.
Contact with the dirty bits of pets should be minimized.
Online Resources
References