A stem cell transplant is a medical procedure that replaces damaged or diseased bone marrow with healthy stem cells. These stem cells can come from the patient (autologous transplant) or a donor (allogeneic transplant). The procedure is often used to treat conditions like leukemia, lymphoma, and other blood disorders. Before the transplant, patients usually undergo chemotherapy or radiation to prepare their bodies. After the transplant, the new stem cells help produce healthy blood cells, which can improve the patient's immune system and overall health. Recovery can take time, and patients are closely monitored for complications.