Bone marrow is the primary tissue in the body that produces blood cells. Hematopoietic stem cells are immature cells found in the bone marrow that give rise to all different types of blood cells (red blood cells, white blood cells, and platelets). These hematopoietic stem cells are utilized in stem cell transplants.

During transplantation, stem cells are delivered intravenously to the patient (recipient), typically through an indwelling device called a central venous catheter. Following transplantation, these immature cells engraft in the bone marrow and mature into essential blood cells, including:
* Red blood cells, which carry oxygen
* Platelets, which aid in blood clotting
* White blood cells, which fight infections

The purpose of a bone marrow transplant is to replace damaged or diseased stem cells with healthy ones. This process enables the body to produce sufficient white blood cells, platelets, or red blood cells to prevent infections, address bleeding disorders, or combat anemia.

There are different types of hematopoietic stem cell transplants, varying based on the source of the stem cells:
* Bone Marrow Transplant (BMT): Stem cells are collected directly from the bone marrow.
* Peripheral Blood Stem Cell Transplant (PBSCT): Stem cells are collected from the circulating blood.
* Cord Blood Transplant (CBT): Stem cells are obtained from the placenta and umbilical cord of a newborn baby.