Stem Cells Transplant: The Basics
Stem cells play a central role in producing healthy blood cells, and have the unique capability of reproducing themselves for long periods of time. Stem cells also have the capacity to differentiate themselves into specialized cells so as to become, for example, muscle cells, nerve cells, and blood cells.
Certain diseases and disorders can affect an individual's healthy bone marrow functioning, which can result in a deficiency in the amount of healthy stem cells being released into the body. Since one of the features of stem cells is to produce healthy blood cells, this can lead to the body's inability to resist certain types of infection and diseases. Many of these diseases can be treated by a stem cell transplant, making a stem cell transplant essential under certain circumstances.
The Stem Cell Transplant
A stem cells transplant is a procedure in which healthy stem cells are used to replace damaged stem cells in the body. These new stem cells travel through the patient's bloodstream, making their way to the bone marrow, the primary source of stem cells in adults.
Prior to transplant, scientists will differentiate the stem cells by using a chemical signal to manipulate them in order to produce specialized cells. The exact place and means of transplantation will depend on which part of a patient's body it is hoped to affect. For example, in cases of leukemia, stem cells will be manipulated to become white blood cells and transplanted into the blood stream.
In order to transplant new stem cells into the body, a patient must first undergo high doses of chemotherapy to destroy all stem cells in the bone marrow, including diseased as well as normal stem cells. Once the new stem cells are transplanted, usually by injection, they will gradually begin to divide and differentiate into different types of blood cells to rebuild a healthy immune system.
Types of Stem Cell Transplants
Three basic types of stem cell transplants exist, while two others are still under clinical trials. The three common stem cell transplants are:
- Autologous transplants involve healthy stem cells retrieved from the patient's own body.
- Allogeneic stem cell transplants are donated stem cells given to a patient by either a family member or an unrelated person. This procedure also has the added benefit of using more than one donor.
- Syngeneic stem cell transplants involve stem cells from a patient's identical twin.
The two types of stem cell transplants currently undergoing clinical trials are:
- Tandem Autologous stem cell transplant. This would involve two autologous transplants received by a single patient within a six-month period.
- Mini Allogeneic or Nonmyeloablative stem cell transplant. This procedure would allow a patient to undergo a less intense preparatory process prior to the transplant.
In addition, the different sources from which stem cells are retrieved are better suited for treating some conditions over others. A stem cell donation must also "match" the patient being treated in order to be successful.