All about hematopoietic stem cell transplantation

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The Food and Drug Administration (FDA) has approved the use of stem cell transplants to treat:

• some types of cancer
• some blood disorders
• some immune system disorders

Some specific examples include:

• multiple myeloma
• leukemia
• some lymphomas
• aplastic anemia
• thalassemia
• sickle cell disease
• severe combined immune deficiency syndrome, which affects some newborns

Stem cell transplantation has also shown promise as a treatment for some neurological diseases, such as multiple sclerosis (MS).

However, the FDA has not yet approved this as an MS treatment, and it warns against undergoing any unapproved procedures due to safety concerns.

Stem cells can come from:

• blood
• the umbilical blood
• bone marrow

Who donates stem cells?

A person can receive stem cells from a donor or their own body.

In allogeneic HSCT, a donor supplies stem cells. Their tissue and blood types need to match those of the recipient, so donors are often close relatives.

Clinicians check for proteins called human leukocyte antigens to compare types of blood and tissue and check whether two people are a match.

In autologous HSCT, stem cells are harvested from the person who needs the treatment. Then, the cells are reintroduced into their body in a targeted way.

Peripheral blood

Circulating blood contains stem cells, and a person with cancer may receive stem cells from their own blood after chemotherapy. There must be no cancer cells left in the body when the person has stem cell treatment.

Chemotherapy and radiation that targets bone marrow can remove stem cells from the area. So after treatment, it can help to reintroduce stem cells into the body. These new stem cells can take root without competition from cancer cells and help produce healthy blood.

This process, called autologous HSCT or “conditioning,” involves the following steps:

• The person takes medication to stimulate stem cell production for around 4 days.
• They have a blood test to check whether there are enough stem cells to harvest.
• If there are, the person undergoes a process that involves drawing blood, which passes through a machine and reenters the body through the other arm.
• This process takes about 3 hours, and the person remains awake.
• The person may need to repeat the process the next day if too few cells were collected the first time.

Umbilical cord blood

Umbilical cord blood contains more stem cells than circulating blood, which makes it particularly suitable. The stem cells can be transplanted into the same person or someone with matching blood and tissue types.

To harvest umbilical stem cells, a healthcare professional collects 40–70 milliliters of blood from the fetal cord immediately after clamping it at both ends. They draw the sample from the area between the two clamps, freeze the sample, and store it in a cord blood bank, in case the person ever needs it.

Bone marrow

If a person donates bone marrow, whether for their own needs or someone else’s, they can expect the following:

• They will have a general anesthetic.
• The doctor will use a needle and syringe to remove around 2 pints of bone marrow from the hip bone, possibly from several locations. This takes 1–2 hours.
• Afterward, there may be some pain and marks on each side of the hips where the doctor inserted the needle.

There is a risk of infection, especially for people who receive stem cells from a donor.

Someone with cancer may have chemotherapy before the transplant. This stops the body from rejecting the transplanted cells, but it also suppresses the ability to fight infections.

Some people develop hepatic veno-occlusive disease with additional kidney or lung abnormalities after having HSCT. Doctors can treat this using a medication called defibrotide sodium (Defitelio).

Another risk associated with allogeneic stem cell transplant is graft-versus-host disease. This happens when donated cells attack a person’s tissues. The less exact the match between the donor and recipient, the higher the risk of this issue. Doctors may use drugs to reduce the risk.

Complications for donors

Bone marrow donors may experience:

• tiredness
• discomfort
• aching in and around the lower back and hips

These usually pass after a few days. Over-the-counter acetaminophen (Tylenol) and nonsteroidal anti-inflammatory drugs, or NSAIDs, such as ibuprofen (Advil), can help.

A doctor may also recommend taking an iron supplement until the red blood cell count returns to normal. Many donors can return to their daily routines after resting for a few days, but it may take 2–3 weeks to recover fully. The bone marrow usually replenishes itself in 4–6 weeks.

Researchers are looking into other uses of stem cell transplants. Because these cells have regenerative properties, they may help repair damaged tissues and treat diseases that involve nerve damage, for example.

In one 2016 study, people with severe MS experienced significant improvements after undergoing HSCT. Inflammation decreased, symptoms stopped worsening, and some people had better mobility.

A 2017 review also supported the use of HSCT as an MS treatment and suggested that it might help treat other neurological and neuroinflammatory diseases, such as:

• stiff person syndrome, which involves muscles stiffness and spasms
• various peripheral neuropathies
• myasthenia gravis

Meanwhile, a 2019 review suggested that stem cells might help treat neurodegenerative diseases, such as Parkinson’s and Alzheimer’s, and might also support the healing of wounds, including those in dental tissue.

The researchers note that while many obstacles remain, HSCT and other stem cell therapies might one day provide cures for a range of diseases.

Doctors sometimes use stem cell therapy to help treat some types of cancer, some blood disorders, and some immune conditions.

Stem cell transplantation also shows promise as a treatment for certain neurological and autoimmune diseases, such as MS, but more research is needed before the FDA can approve it for these purposes.