Hematopoietic, or blood-forming, stem cells have been used to treat blood diseases for decades. Transplanting donor cells helps completely replace a patient's own blood cells (restoring healthy hematopoiesis), thereby overcoming the disease. This treatment helps treat hereditary blood disorders and blood cancers. Current data indicate that cancer develops in one in a thousand people after a stem cell transplant, so scientists decided to determine whether the treatment could actually contribute to the development of cancer. The findings were published on the website Nature.
A team from the United States recruited 32 participants—16 donor-recipient pairs. Participants had received donor cell transplants between 7 and 46 years ago for blood cancer. Genome sequencing revealed that mutations developed at a rate of 2% per year in donors, and at a rate of 2.6% in recipients.
"This is surprising. In fact, there were very few new mutations in the stem cells. This means the recipients' cells age at the same rate as the donors' cells. Therefore, they don't have an increased risk of cancer," said hematologist Spencer Champman, co-author of the study.
Previously, the scientist conducted a similar clinical study involving 10 people and came to similar conclusions: recipients had only a slightly higher number of mutations compared to donors.
Other researchers noted that the stability of mutation risks over time indicates "a significant depth of regenerative capacity of the hematopoietic system."
Importantly, multiple cell mutations were more common in recipients. This explains the rare incidence of cancer in people who received HSC transplants.
Scientists will continue conducting similar studies to gather more information about the risks and long-term health consequences of HSC transplantation. Meanwhile, the data already available will form a significant part of the evidence base for the safety of this treatment across various diagnoses and cell delivery methods, including gene therapy.
Today, stem cell therapy is being studied in many areas. Research shows excellent promise for treating HIV, osteoarthritis, Alzheimer's disease, diabetes, and other conditions.
