CD34+ cells are a population of cells found in the human body, identified by a protein marker called CD34 on their surface. These cells are an immature or progenitor cell type, capable of developing into various specialized cells. Their properties make them a subject of interest in biological research and medical treatments.
Understanding CD34+ Cells
CD34+ cells are naturally abundant in several locations throughout the human body. The primary reservoir for CD34+ cells is the bone marrow, the spongy tissue found inside bones, where they play a central role in blood cell production. They are also present in the peripheral blood, circulating in smaller numbers, and are particularly rich in umbilical cord blood collected shortly after birth.
Biological Roles of CD34+ Cells
CD34+ cells function as hematopoietic stem cells (HSCs), generating all types of mature blood cells. These include red blood cells, which carry oxygen, various types of white blood cells that fight infection, and platelets, which are involved in blood clotting.
These cells have the capacity for self-renewal, producing more stem cells while also differentiating into specialized progeny. This ensures a steady supply of new blood cells and maintains the stem cell pool. Beyond blood formation, CD34+ cells also contribute to the body’s regenerative processes, participating in tissue repair and maintenance.
Therapeutic Applications
CD34+ cells are used in medical treatments, particularly hematopoietic stem cell transplantation (HSCT). This procedure is frequently used to treat various blood cancers, such as leukemias and lymphomas, where a patient’s diseased bone marrow is replaced with healthy stem cells. CD34+ cells are also employed to address other severe blood disorders like aplastic anemia, which involves bone marrow failure, or sickle cell disease, a genetic disorder affecting red blood cells.
In these transplantations, the infused CD34+ cells engraft in the patient’s bone marrow, subsequently repopulating the entire blood and immune system. This process restores the patient’s ability to produce healthy blood components, which is crucial after high-dose chemotherapy or radiation therapy that often precedes transplantation. Beyond blood-related conditions, the potential of CD34+ cells is being explored in regenerative medicine for non-blood conditions.
Research is ongoing into their use for repairing damaged heart tissue following a heart attack or for addressing neurological conditions such as stroke. These applications often involve the cells’ general regenerative and tissue repair capabilities, which are still largely in experimental or clinical trial phases. The aim is to leverage their ability to differentiate or secrete factors that promote healing and regeneration in various organ systems.
Obtaining and Administering CD34+ Cells
Collecting CD34+ cells for therapeutic use involves several methods, each with its own advantages. One traditional approach is bone marrow aspiration, where cells are directly extracted from the bone marrow, typically from the hip bone, under general anesthesia. This method yields a rich source of hematopoietic stem cells.
Another common collection method is peripheral blood apheresis. Here, a donor receives medication, such as granulocyte-colony stimulating factor (G-CSF), for several days before collection to stimulate the bone marrow to release CD34+ cells into the bloodstream. Blood is then drawn from the donor, passed through an apheresis machine that separates the CD34+ cells, and the remaining blood components are returned to the donor. Umbilical cord blood, collected from the placenta and umbilical cord after birth, is a third source, rich in CD34+ cells and can be stored for future use.
Once collected, these cells are typically administered to the patient intravenously, similar to a standard blood transfusion. The cells travel through the bloodstream to the bone marrow, where they “home” to appropriate niches and begin the process of engraftment and reconstitution of the blood system. Successful transplantation relies significantly on matching human leukocyte antigen (HLA) types between donor and recipient to reduce the risk of rejection or graft-versus-host disease.
References
1. “Hematopoietic Stem Cell Transplantation (HSCT) – NCI.” https://www.cancer.gov/about-cancer/treatment/types/stem-cell-transplant. [Accessed 2025-07-27].
2. “Bone marrow transplant – Mayo Clinic.” https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/about/pac-20384854. [Accessed 2025-07-27].