Stem Cell Transplants
Every 10 minutes, an American dies from a blood cancer. Leukemia causes more deaths than any other cancer that children and teenagers face. To treat blood cancer, doctors began performing stem cell transplants about 50 years ago. Transplants help the body's blood-making organ, bone marrow, regain function impaired by the cancer or chemotherapy. Doctors make the transplant decision depending on the cancer type, the patient's age, other treatment options available and whether a stem cell donor is a good match. Stem cells are collected from donors, the patient or umbilical cord blood, using either circulating blood or the marrow. The first two procedures are called allogeneic and autologous, based on who's providing the cells.
Donor vs Patient Cells
Autologous transplants use the patient's stem cells and are considered safer, but have a higher risk for cancer recurrence. Allogeneic transplants, often using a sibling's matched cells, usually have a higher risk of side effects or death. Sometimes the donor transplants have better results because the new stem cells may recognize any remaining cancer cells as foreign and will attack them, according to the American Cancer Society.
Before a patient can donate his own cells, doctors often give him a drug such as Plerixafor and a white cell growth factor to help transfer cells from the marrow to the blood.
Bone Marrow Aspiration
If doctors are removing stem cells from bone marrow, the patient is put under general anesthesia, and a needle is inserted into the pelvic area. Using bone marrow aspiration, the doctor withdraws a small amount of the marrow's liquid, which can be done many times to collect enough cells, depending on how much the patient needs. Bone marrow cells are placed into a blood bag and often frozen. Pathologists look at the marrow sample under a microscope to diagnose cancer cells and measure how much iron and other substances that blood cells need to grow are in the marrow. If an infection is found, the patient will receive antibiotics.
Using Blood Vessels
When physicians take blood from vessels, the procedure is called apheresis. A doctor may prescribe the growth factor G-CSF to stimulate the growth of new stem cells entering the bloodstream. G-CSF is a naturally produced protein.
The donor's blood is removed from a vein and enters a machine that separates the stem cells; the remaining blood leaves the machine and re-enters the arm through a needle or catheter. Donation takes four or five hours and may need to be repeated the next day if more stem cells are needed.
Treatment Kills Cancer Cells
Before receiving a transplant, the patient will undergo high-dose chemotherapy and sometimes radiation to the entire body, except for the lungs, heart and kidneys. These treatments kill any remaining cancer cells as well as healthy bone marrow cells. Doctors thaw the frozen stem cells and perform a transfusion. After several days, the transfused cells start to grow and produce new blood cells.
During the following three or four weeks, the patient's at high risk for serious infections because her white blood cell count is low. She may also bleed if her platelet count drops. Blood and platelet transfusions and antibiotics can prevent or treat infections or excessive bleeding.
Most patients stay in the hospital's germ-isolation unit until their white blood cell count rises above 500. Once the white cell count reaches 1,000, they can leave the hospital, but they usually visit an outpatient clinic every day for several weeks for further blood tests.
Donating Stem Cells
People ages 18 to 60 who want to donate stem cells can contact the National Marrow Donor Program to find the nearest donor center. Pregnant women seeking to donate the child's umbilical cord blood can also use the program. (see Resources)
Tags: stem cells, cancer cells, cell count, blood cancer, blood cell, blood cell count