What Is Hematopoietic Stem Cell Transplantation (HSCT), and How Can It Treat Blood Diseases?
Overview: Hematopoietic stem cell transplantation (HSCT) is a treatment approach that helps patients rebuild normal hematopoiesis and immune function by infusing healthy hematopoietic stem cells. It is mainly used to treat certain hematologic malignancies, hematopoietic failure disorders, and some genetic diseases and immunodeficiency disorders. Depending on the patient’s disease type, risk level, and physical condition, doctors will choose different treatment options, such as autologous hematopoietic stem cell transplantation or allogeneic hematopoietic stem cell transplantation.
Hematopoietic stem cell transplantation (HSCT) is a treatment that gives healthy blood-forming stem cells through a vein. These cells travel to the bone marrow, begin to grow, and help rebuild normal blood production and immune function.
When patients and families first hear the term “stem cell transplant,” they may wonder whether it means replacing the bone marrow. HSCT is not simply a bone marrow replacement. It uses healthy stem cells to help the body build a new blood-forming system.
Hematopoietic stem cells can continuously produce red blood cells, which carry oxygen; white blood cells, which help fight infection; and platelets, which help stop bleeding and form blood clots.
When a disease damages the bone marrow or causes abnormal cells, such as leukemia cells, to grow out of control, the body may not make enough healthy blood cells. This can lead to anemia, a higher risk of infection, and bleeding. HSCT aims to restore healthy blood production with new stem cells.
Why can HSCT treat blood diseases?
HSCT can treat some blood diseases in two main ways.
1. Rebuilding the blood-forming system. Hematopoietic stem cells can renew themselves and develop into different blood cells. After they enter the body, healthy stem cells can engraft in the bone marrow and begin producing new blood cells. This may help rebuild blood production in people whose bone marrow has been seriously damaged, including some patients with leukemia or aplastic anemia.
2. Providing an immune effect against cancer. In an allogeneic HSCT, immune cells from the donor may recognize and attack some cancer cells that remain in the patient’s body. This is called the graft-versus-leukemia (GVL) effect. It is one of the important ways that allogeneic HSCT can treat certain blood cancers.
What is the difference between HSCT and a bone marrow transplant?
People often use “bone marrow transplant” to mean HSCT, but the terms are not exactly the same. In the past, most blood-forming stem cells were collected from bone marrow, so “bone marrow transplant” became the common name.
Today, stem cells may come from bone marrow, peripheral blood, or cord blood. Peripheral blood is now widely used and can be collected with an established blood-cell separation process. Cord blood also contains hematopoietic stem cells and may be used for some patients. For this reason, “hematopoietic stem cell transplantation” is the more accurate medical term
What are the main types of HSCT?
The two main types are autologous HSCT and allogeneic HSCT.
Autologous HSCT uses the patient’s own stem cells. The cells are collected and stored before high-dose treatment, then returned to the patient to help blood production recover. This approach is commonly used for some lymphomas, multiple myeloma, and selected other blood diseases.
Allogeneic HSCT uses stem cells from a healthy donor. The donor may be a fully matched sibling, an unrelated donor, or a haploidentical family member. In addition to rebuilding blood production, donor immune cells may provide an anti-cancer effect. Allogeneic HSCT is therefore an important treatment option for some patients with high-risk blood cancers.
Who may need HSCT?
HSCT is not needed for every person with a blood disease. The transplant team considers the type of disease, risk group, chromosome and gene test results, response to treatment, age, and overall health.
Some patients with high-risk acute leukemia, relapsed or treatment-resistant blood cancers, or high-risk myelodysplastic syndromes (MDS) may be considered for HSCT when medicines alone are unlikely to provide long-term control.
HSCT may also be considered for severe bone marrow failure, such as severe aplastic anemia, and for selected inherited blood disorders or congenital immune deficiencies.
Why is a full assessment needed before HSCT?
HSCT is a complex treatment, and it is not always best to proceed immediately after diagnosis. Before transplant, patients usually have bone marrow tests, immunophenotyping, chromosome and gene tests, measurable residual disease testing, heart and lung assessments, and infection screening.
These tests help the team decide whether the patient can safely undergo transplant, which type of transplant and donor source may be most suitable, and when the transplant should take place. For some blood cancers, better disease control before transplant may improve the chance of a good outcome.
Summary
HSCT is an important treatment that can rebuild the blood-forming and immune systems. It is not simply a “bone marrow replacement.” The decision requires careful assessment of the disease, risk level, genetic findings, treatment response, and the patient’s overall health. For selected patients with blood cancers, bone marrow failure, inherited disorders, or immune diseases, HSCT may offer long-term remission and, in some cases, a chance of cure.