Continued

Peripheral Blood Stem Cells
Ordinarily, there are very few stem cells circulating in the peripheral blood. In order to collect a sufficient quantity for transplantation, injections of a medication called filgrastim must be administered. This is a drug that mobilizes stem cells to migrate from the bone marrow into the blood stream. Donors experience side effects similar to flu-like symptoms while taking this medication. The stem cells are collected through a procedure called apheresis, which is similar to the process used in platelet donation. A cell-separating machine filters out the stem cells, which can then be infused into the recipient.

Cord Blood
The placenta represents a rich source of stem cells, and these cells can be collected at birth. Umbilical cord blood units are tissue typed and frozen in liquid nitrogen through a process known as cryopreservation. Because the volume collected is so small, cord blood transplants are most successful with children. However, there is research underway to expand the units ex-vivo, which will provide a sufficient quantity of stem cells for transplantation in adults. Donor-recipient pairs need not necessarily be as closely matched with cord blood transplants, because of the fact that antibodies are less prominent.

STEPS

Preparation
In preparation for the transplant, patients are given a central venous line in order to avoid the need for repeated needle sticks. The line is inserted under anesthetic using a process known as x-ray guidance. The line is used to provide medications, nutrition, hydration, transfusions (including the transplant itself) and to draw blood samples. While it can be a little overwhelming at first, most patients grow to appreciate the convenience of having the line in place. There are several different types of lines that can be used. Among the most common are the Hickman Line and the Portacath. Most transplant centers try to have the line removed prior to the patient returning home. However, some patients are discharged with the line still in place if needed.

Conditioning
The conditioning phase begins the actual transplant process. This is the administration of the high-dose chemotherapy and / or radiation therapy (total body irradiation). This process ablates the existing immune system and marrow function. Some transplant centers administer conditioning on an outpatient basis, while most still require patients to be inpatient. Most patients are given a “rest day” before the actual transplant. The conditioning process is significantly different in the case of non-myeloablative or “mini” transplants.