Autologous stem cell transplantation is a medical procedure where a patient's own stem cells are collected, processed, and then returned to their body. This treatment is often used for conditions like blood cancers or bone marrow disorders. The process begins with harvesting stem cells from the patient's blood or bone marrow, followed by high-dose chemotherapy or radiation to eliminate diseased cells. After the treatment, the collected stem cells are infused back into the patient to help restore healthy blood cell production. This approach reduces the risk of rejection since the cells are the patient's own, making it a safer option compared to allogeneic stem cell transplantation, which uses donor cells.