Hematopoietic Stem Cells: Can They Save Lives?

Hematopoietic stem cells (HSCs) are blood-forming stem cells that produce every type of blood cell in the body: red blood cells, white blood cells and platelets. They are found in bone marrow, in small numbers in circulating blood, and in umbilical cord blood. Doctors use them in stem cell transplants to treat blood cancers, inherited blood disorders and immune system diseases.

Every day, your body replaces billions of blood cells. HSCs make this possible. When they stop working properly, because of a disease like leukaemia or thalassemia, a transplant of healthy HSCs can rebuild the entire blood and immune system.

In this article, you’ll learn what HSCs are, where they come from, how HSC transplants work, which conditions they treat, and why your baby’s cord blood is one of the most valuable sources of these cells.

Key Takeaways

• Hematopoietic stem cells are multipotent blood-forming cells that produce red blood cells, white blood cells and platelets.
• HSCs are found in bone marrow, peripheral blood and umbilical cord blood.
• HSC transplants are used to treat blood cancers such as leukaemia and lymphoma, inherited blood disorders such as thalassemia, and certain immune deficiencies.
• Transplants can be autologous (the patient’s own cells) or allogeneic (cells from a matched donor).
• Cord blood HSCs need a less strict tissue match than bone marrow and carry a lower risk of graft-versus-host disease.
• Cord blood can only be collected at birth, through a quick, painless procedure that doesn’t affect mother or baby.

What Are Hematopoietic Stem Cells?

Hematopoietic stem cells are a type of stem cell responsible for producing all the blood and immune cells in the body. The word “hematopoiesis” comes from two Greek words: haima, meaning blood, and poiesis, meaning to make. HSCs are often simply called “blood stem cells.”

HSCs have two defining abilities:

• Self-renewal: they can divide to make more HSCs, so the supply never runs out over a lifetime.
• Differentiation: they can mature into every type of blood cell.

HSCs are multipotent, not pluripotent. This means they can become any cell within the blood and immune system, but not unrelated cells such as nerve or muscle cells. Pluripotent cells, like embryonic stem cells, can become almost any cell type.

What Cells Do HSCs Produce?

HSCs develop along two main branches:

• Myeloid cells: red blood cells (carry oxygen), platelets (help blood clot), and white blood cells such as neutrophils and monocytes (fight infection).
• Lymphoid cells: T cells, B cells and natural killer (NK) cells, which make up the adaptive and innate immune system.

In the lab, HSCs are identified using a surface marker called CD34. Stem cell banks and transplant centres count CD34+ cells to judge how many usable stem cells a sample contains.

Where Are Hematopoietic Stem Cells Found?

HSCs used in transplants come from three sources: bone marrow, peripheral blood and umbilical cord blood. Each has its own advantages.

Bone marrow is the body’s main HSC factory and was the first source used for transplants.

Peripheral blood normally has very few HSCs. Donors receive growth-factor injections for a few days to push HSCs from the marrow into the bloodstream. It is now the most common source for adult transplants.

Umbilical cord blood is rich in young, naive HSCs. It can only be collected in the minutes after birth, which is why parents choose to bank their baby’s cord blood. Once frozen, these cells can be stored for decades.

What Is Hematopoietic Stem Cell Transplantation?

Hematopoietic stem cell transplantation (HSCT) replaces a patient’s diseased or damaged blood-forming cells with healthy HSCs. It is often called a stem cell transplant or, when the cells come from marrow, a bone marrow transplant.

How Does an HSC Transplant Work?

1. Conditioning: the patient receives chemotherapy, and sometimes radiation, to clear out diseased cells and make room for new ones. This usually takes several days.
2. Infusion: the healthy HSCs are given through a vein, much like a blood transfusion. This step is not surgery and is usually painless.
3. Engraftment: the new HSCs travel to the bone marrow and start making blood cells. This typically takes two to four weeks, and sometimes longer with cord blood.
4. Recovery: the patient is closely monitored for infections and complications while the immune system rebuilds. Full immune recovery can take months.

Autologous vs Allogeneic Transplants

Why HLA Matching Matters

HLA (human leukocyte antigen) markers are proteins on cells that help the immune system tell “self” from “foreign.” In an allogeneic transplant, the closer the HLA match between donor and patient, the lower the risk of rejection and graft-versus-host disease.

Siblings have a 25% chance of being a full match. Many patients, especially in India, struggle to find a matched unrelated donor. This is one reason cord blood, which tolerates a less strict match, is an important source.

What Conditions Can HSCs Treat?

HSC transplants are an established treatment for many serious blood, immune and metabolic conditions. Stem cells are used in the treatment of 80+ conditions, including:

Blood Cancers

Acute and chronic leukaemias, Hodgkin and non-Hodgkin lymphoma, multiple myeloma and myelodysplastic syndromes. For many of these, an allogeneic transplant offers the best chance of long-term remission.

Inherited Blood Disorders

Thalassemia major and sickle cell disease. A successful allogeneic transplant can be curative, replacing the faulty blood-forming system with a healthy one. Thalassemia is especially relevant in India, which has one of the largest numbers of affected children in the world.

Bone Marrow Failure

Severe aplastic anaemia and Fanconi anaemia, where the marrow stops producing enough blood cells.

Immune Deficiencies

Inherited conditions such as severe combined immunodeficiency (SCID), in which a child is born without a working immune system.

Inherited Metabolic Disorders

Certain rare conditions, such as Hurler syndrome, where donor cells supply an enzyme the body cannot make.

Severe Autoimmune Diseases

For some patients with severe, treatment-resistant multiple sclerosis or systemic sclerosis, autologous HSCT is used to “reset” the immune system. This is a specialised option, considered only when standard treatments have failed.

Note: For inherited and genetic conditions, a child’s own cord blood usually can’t be used, because the cells carry the same genetic fault. In these cases, cells from a matched sibling or donor are needed.

What Are the Risks of HSC Transplantation?

HSC transplants can save lives, but they are intensive procedures with real risks. Doctors weigh these carefully against the benefits for each patient.

• Infections: conditioning chemotherapy temporarily wipes out the immune system, so patients are vulnerable to bacterial, viral and fungal infections until the new cells engraft.
• Graft-versus-host disease (GVHD): in allogeneic transplants, donor immune cells may attack the patient’s tissues, most often the skin, liver and gut. GVHD can be acute (within the first few months) or chronic (later and longer-lasting).
• Graft failure: occasionally, the transplanted cells don’t take hold in the bone marrow.
• Side effects of conditioning: nausea, mouth sores, hair loss and, in the long term, possible effects on fertility and organ function.

How Cord Blood Lowers the Risk of GVHD

Immune cells in cord blood are immature and less likely to react against the patient’s body. As a result, cord blood transplants carry a lower risk of severe GVHD than bone marrow or peripheral blood transplants, even with a less complete HLA match.

Why Is Cord Blood a Valuable Source of HSCs?

Cord blood has been used in transplants since 1988 and is now a recognised source of HSCs worldwide. It offers several practical advantages:

• Ready when needed: banked cord blood is already tested and frozen, so there’s no wait to find and prepare a donor.
• Less strict matching: this widens the chance of finding a suitable unit, which matters for families of diverse genetic backgrounds.
• Lower GVHD risk: immature immune cells are less likely to attack the patient.
• Young, healthy cells: collected at birth, they haven’t been exposed to ageing or environmental damage.
• Safe, painless collection: it takes a few minutes after delivery and doesn’t affect the birth.

Cord blood can only be collected once, at birth. Parents who want to preserve it should plan ahead and choose a cord blood bank before delivery.

Hematopoietic vs Mesenchymal Stem Cells

The umbilical cord holds two different types of stem cells, and parents often confuse them.

Banking both cord blood and cord tissue preserves both cell types for the future.

Conclusion

Hematopoietic stem cells are the foundation of the body’s blood and immune system. Through stem cell transplants, they offer a proven treatment for blood cancers, inherited blood disorders and immune deficiencies.

Umbilical cord blood is one of the most accessible sources of these cells. It is quick to use, needs a less strict match and carries a lower risk of GVHD. And because it can only be collected at birth, the decision to preserve it has to be made before your baby arrives.

If you’re expecting, learn more about LifeCell stem cell banking or book a free consultation with our experts. You can also call us at 1800-266-5533.

Frequently Asked Questions

Are hematopoietic stem cells pluripotent or multipotent?

Hematopoietic stem cells are multipotent. They can develop into all types of blood and immune cells, including red blood cells, white blood cells and platelets, but not into unrelated cell types such as nerve or muscle cells.

Where are hematopoietic stem cells found?

HSCs are found mainly in the bone marrow. Small numbers circulate in the bloodstream, and umbilical cord blood is a rich source at birth. All three can be used for stem cell transplants.

What is the difference between hematopoietic and mesenchymal stem cells?

Hematopoietic stem cells form blood and immune cells and are found in cord blood and bone marrow. Mesenchymal stem cells form bone, cartilage and connective tissue and are found in cord tissue. HSCs are an established transplant treatment, while MSCs are mainly studied in clinical trials.

Is a hematopoietic stem cell transplant painful?

The infusion of stem cells is usually painless and is given through a vein like a blood transfusion. However, the overall treatment, including conditioning chemotherapy and recovery, can be demanding and involve side effects.

Can cord blood stem cells be used for siblings?

Yes. Cord blood can be used for a sibling if the HLA match is suitable. Siblings have a 25% chance of being a full match and a higher chance of a partial match, which is often acceptable for cord blood transplants.

How long can cord blood HSCs be stored?

When cryopreserved under controlled conditions, cord blood stem cells can be stored for decades. Studies have shown viable cells after more than 25 years of storage.