When all the drugs have been given it may be necessary to wait for one or two days to allow the drugs to be eliminated from the body before the stem cells are returned. The stem cells are given back through the central line.
The stem cells have been frozen in a preservative called DMSO. This preservative is toxic to the cells when they are thawed. Therefore, the stem cells are brought to the patient's room when they are still frozen in the vapor phase of liquid nitrogen. The stem cells are stored in a bag surrounded by an aluminum protective case. This is removed from the cold storage.
The stem cells are thawed rapidly in a warm water bath. Once the cells are thawed they are drawn from the bag into a syringe. Once the syringe is full, the thawed cells are then injected into the patient. If there is more than one bag to thaw, the second bag is thawed after the cells from the first bag have been given.
Most people tolerate the re-infusion of stem cells well; however, some people get symptoms from the DMSO preservative. Altered taste, flushing and a distinctive smell on the breath are common. On rare occasions the heart rate slows down or speeds up, or there may be difficulty breathing. Therefore, patients are routinely connected to heart monitors that measure the amount of oxygen in the blood, among other things. The side effects from DMSO are related to how much is given. Generally, stem cells have a smaller volume and therefore less DMSO than bone marrow.
The stem cells are injected relatively quickly, over about five to ten minutes for each syringe. Although reactions are possible, most patients find the stem cell re-infusion itself almost anticlimactic considering how important this step is. The stem cells find their way back to the bone marrow, where they attach themselves to the supporting cells there and start to grow.