Stem cells transplants, also known as bone marrow transplants, are used to treat a variety of diseases, including leukemia, lymphoma, and multiple myeloma. A stem cell donor can be the patient himself, a matched biological family member, or a matched unrelated donor. The three primary methods for stem cell collection are bone marrow extraction, peripheral blood apheresis, and umbilical cord blood harvesting.
Surgically extracting the bone marrow for stem cell collection takes place in an operating room where the donor is under general anesthesia. During the surgery, the donor's bone marrow is extracted from several puncture sites in the hipbones using a special needle. Approximately 1 to 2 quarts (.94 to 1.89 liters) of bone marrow, which represent about five percent of a patient's total marrow, is harvested. After the bone marrow is extracted, it is filtered and any fat or fragments of bone are removed. The donation is then transported to the laboratory to be processed before being frozen for transplantation at a later date or transplanted immediately into the recipient.
In recent years, peripheral blood apheresis has become a popular method for stem cell collection, as it does not involve a surgical procedure. To prepare for apheresis, the donor usually receives a special medication, known as granulocyte stimulating factor (G-CSF), for several days to stimulate the marrow to release more stem cells into the blood stream. Blood is then removed from the donor through an IV placed in a large vein in the arm or a central line placed in the chest, neck, or under the arm. The blood next passes through a machine that separates the stem cells from the red cells, white cells, and platelets. The cells that are not needed are then returned to the donor through a different vein in the arm or through a central line.
Umbilical cord blood harvesting has also become a popular method of stem cell collection. With this method, the stem cells are simply removed from the discarded umbilical cord and placenta of a newborn at delivery. The main advantage of this type of stem cell collection is that it does not hurt or inconvenience the donor, as the materials would have been discarded anyway. These stem cells can be frozen for an upcoming transplant that has already been scheduled or cryopreserved for any unforeseen needs in the distant future. This method of stem cell collection has traditionally been reserved for those donating to children or small adults, because of the limited number of stem cells available within the umbilical cord and placenta.