Maisonneuve-Rosemont Hospital Université de Montréal

Types of transplants

Hematopoietic stem cell transplantation

In a certain way, a hematopoietic stem cell (HSC) transplant gives the body’s blood and/or immune system a fresh start. The procedure involves replacing diseased cells with healthy ones.

Removing stem cells

HSCs are located mainly in bone marrow, the tissue found in the cavities of the body’s major bones, such as the pelvis. When the body needs new blood cells, HSCs differentiate into white and red blood cells as well as platelets, then leave the bone and pass into the blood stream.

Collecting cells for transplant

Since hematopoietic stem cells are located in bone marrow, collecting these cells may be accomplished through a number of punctures of the pelvic bone. The procedure takes place in an operating room, where donors lie on their stomach and are given a local or general anaesthetic. Transplant surgeons then remove the stem cells within the bone marrow with a needle. The cells for transplant that are collected in this way are referred to as medullary transplants, that is, they are made up of hematopoietic stem cells from bone marrow.

Sometimes, in very specific situations, HSCs leave the bone cavity without first differentiating and enter the blood stream, which makes it much simpler for the medical team to collect them. This is done by a device to which the patient or donor is connected through two intravenous routes. One of these is used to draw blood, which is then passed through the cytapheresis device that will filter out the stem cells in it. The other blood cells will subsequently be returned to the patient through the second intravenous. All the HSCs harvested by the device in this way will make up this type of transplant, known as a peripheral stem cell transplant.

Types of transplants

A HSC transplant can come from three sources: