Stem cell transplant works by replacing damaged or diseased bone marrow with healthy stem cells. Here's a breakdown of the process:
1. Preparation: Conditioning Therapy
Before the transplant, the patient undergoes conditioning therapy, which typically involves high-dose chemotherapy, sometimes with radiation therapy. The goals of this therapy are to:
- Destroy diseased cells: Eliminate cancer cells or other abnormal cells causing the illness.
- Suppress the immune system: Prevent the body from rejecting the transplanted stem cells.
- Create space in the bone marrow: Make room for the new stem cells to grow.
2. Stem Cell Infusion
After conditioning, the stem cells are infused into the patient's bloodstream, similar to a blood transfusion. These stem cells can come from:
- Autologous transplant: The patient's own stem cells, collected and stored before conditioning therapy.
- Allogeneic transplant: Stem cells from a matched donor (related or unrelated).
- Syngeneic transplant: Stem cells from an identical twin (rare).
3. Homing and Engraftment
Once in the bloodstream, the stem cells travel to the bone marrow. This is called "homing." They then begin to multiply and produce new, healthy blood cells. This process is called "engraftment." Engraftment usually takes a few weeks, during which the patient is at high risk of infection and bleeding.
4. Recovery and Monitoring
After engraftment, the patient's blood counts gradually recover. The patient will need close monitoring for signs of:
- Infection: Due to a weakened immune system.
- Graft-versus-host disease (GVHD): In allogeneic transplants, the donor stem cells may attack the patient's tissues.
- Relapse: The original disease returning.
In summary, a stem cell transplant involves eliminating diseased cells and bone marrow with chemotherapy, followed by infusion of healthy stem cells that then migrate to the bone marrow and begin producing new, healthy blood cells.
