Part one in a series looking at the processes involved in the most clinically applied form of stem cell therapy: hematopoietic stem cell transplantation
By Michelle Ly
Leukocytes, or white blood cells (WBCs), are an essential part of the immune system. Produced in the bone marrow, healthy WBCs protect the body against infection and pathogens. Cancers such as leukemia or multiple myeloma have the effect of producing abnormal, non-functional white blood cells. To treat these patients and attempt to restore normal WBC levels, chemotherapy and hematopoietic stem cell transplantation is often used.
Hematopoietic stem cell transplantation involves the use of hematopoietic progenitor cells (HPCs) collected from either the bone marrow or the blood. These cells are able to differentiate into all the different lineages of blood cells, including the white blood cells. While both types of stem cell collection are still performed, the use of HPCs derived from blood has grown in popularity.
The process of preparing transplantable HPCs from blood is performed by a specialized team of technicians working in conjunction with medical staff. HPCs are collected from either autologous or allogenic donor blood. Autologous donations are taken from the patient prior to chemotherapy treatment, while allogenic donations are taken from siblings or unrelated donors. The actual donation process takes place within a hospital through a process called apheresis. During apheresis, the donor's blood passes through a machine which separates the blood into its constituent parts. The HPC-containing layer of the blood is kept for further processing, while the remainder is returned to the donor's circulation.
The role of facilities such as the Clinical Cell Therapy group at the BC Cancer Agency is to take the HPC-containing blood product and turn it into a form that is rich in HPCs and capable of being stored until the patient requires a transplant. As this timeline may vary from days to months to years, it is essential that the stem cells are processed and preserved carefully.
How do they do this? In my next post, we'll meet the people behind the process and take a look at how blood product gets from the patient, to the freezer, and back to the patient again.
(Photo by Dale Tidy)