If your child is undergoing an autologous stem cell transplant, doctors will need to collect and store your child’s stem cells. This is done before being admitted into the hospital. In the past, doctors collected stem cells from your child’s bone marrow. This is called bone marrow harvesting. Doctors occasionally collect stem cells this way.
More commonly autologous stem cells are collected from the blood that circulates in the body, called the peripheral blood. This is called a peripheral blood stem cell harvest.
Peripheral blood stem cell harvest
Preparing for the harvest
Three to five days before the harvest, your child will receive daily injections of a synthetic protein called filgrastim (G-CSF or granulocyte colony stimulating factor). The protein helps move the blood stem cells from the bone marrow space into the blood stream.
Before harvesting your child’s stem cells, the nurse will check the amount of platelets in your child’s blood. Your child needs to have at least 50x109 platelet cells/litre of blood.
For the harvesting procedure, doctors need a central venous line (CVL) with two tubes or lumens.
Often children will already have a CVL that is being used for their present therapy. These lines are usually not big or firm enough for collecting stem cells. Most commonly doctors need to insert a new temporary CVL into the femoral vein, which is the large vein in the thigh. This is called a femoral line catheter. After inserting the new line, doctors will start your child’s stem cell harvest.
During the procedure:
1. Blood is withdrawn from your child’s femoral line. In addition to stem cells, the blood contains many other types of cells, such as red blood cells, platelets, and white blood cells. Your child’s blood runs through the flexible tubing which is attached to a machine that separates out blood cells. This is called an apheresis machine. It separates the stem cells, while returning the rest of the blood back into your child. The entire procedure usually takes about four hours to complete.
2. The stem cells are mixed with a preservative called dimethylsulfoxide (DMSO). The cells are then frozen at very low temperatures (cryopreserved), until the day of your child’s transplant.
How will your child feel during the harvest?
During the stem cell harvest, your child may feel:
- light headed
- cold
- numb around the lips
- cramps in the hands. This is caused by a blood-thinning drug that lowers the calcium level in the blood. If the cramping continues after the harvesting, calcium supplements can help.
Bone marrow harvest
Occasionally, doctors may be unable to collect a sufficient amount of stem cells from the peripheral blood. If this happens, they may need to collect cells from your child’s bone marrow. This procedure is called a bone marrow harvest. Your child cannot start preparing for the transplant until doctors collect and store enough stem cells.
How the procedure works
A staff transplant physician together with another BMT fellow will perform the bone marrow harvest.
The procedure will take place in an operating room and takes about one to two hours.
As a parent, staying calm will help your child. The medical team will try to ensure your child is as comfortable as possible.
To take your child's bone marrow cells:
- Your child will be given a general anaesthetic so they will not be awake during the procedure.
- Your child lies down on their stomach.
- Both sides of your child’s hips will be scrubbed with a disinfectant and the surrounding area covered or draped with sterile sheets.
- The doctor inserts a needle through the skin until it touches the top of the hip bone, called the posterior superior iliac crest. This is the largest and uppermost bone in the pelvis and contains a large amount of bone marrow.
- Once the needle touches the hip bone, the doctor pushes the needle through the hard outer layer of the hip bone and into the bone marrow space.
- A syringe is then attached to the needle to draw out a small amount of the red liquid bone marrow from your child. The physicians do multiple injections to collect enough of the bone marrow.
After the procedure
The bone marrow site may be sore for a few days. There may also be a bruise on the site, which will not take too long to heal. To help your child feel better:
- Apply ice packs to the site.
- Encourage your child to walk.
- Give your child pain medicine. The doctor can provide you with a drug prescription.
If the BMT physicians withdraw a lot of bone marrow, they may prescribe an oral iron supplement for your child.
What complications can occur?
Bone marrow harvesting is generally a safe procedure. While your child may feel mildly sore for up to one to two days following the procedure, serious complications rarely occur.
Sometimes problems occur at the site where the bone marrow cells were taken. These include:
- bleeding: There is a higher chance of this happening with children who have pre-existing bleeding problems. In this case, the physician will order platelet and/or plasma transfusions before your child's test to prevent any bleeding that might occur. If bleeding does occur, the nurse will put pressure on site and monitor your child closely.
- infection: If the skin or bone becomes infected and is painful, or there is redness and swelling, the doctor may give your child antibiotics through an IV or by mouth.
Call your doctor right away if your child has:
- more tenderness, pain, redness, or swelling at the biopsy site
- a fever
- bleeding or drainage, such as pus, from the biopsy site. If your child is bleeding, put pressure on the site and call your doctor.