A new study shows that the advantageous effects of gene therapy can be observed several decades after the body clears the transplanted blood stem cells.
Gene Therapy Concept. Image Credit: xsense/Shutterstock.com
The study was carried out by researchers from an international collaboration between Great Ormond Street Hospital, the UCL GOS Institute for Child Health, and Harvard Medical School.
The researchers monitored five patients who were successfully cured of SCID-X1 at GOSH by using gene therapy. For a period of 3 to 18 years, the blood of the patients was regularly tested to identify which types of cells and biomarker chemicals existed in their blood.
The results revealed that although the stem cells that were transplanted during the gene therapy had been cleared by the patients, the all-significant corrected immune cells, known as T-cells, were still forming.
Gene therapy functions by initially eliminating some of the blood-forming stem cells of the patients. It is these stem cells that create all kinds of blood and immune cells. Then, a viral vector is used to administer a new copy of the defective gene into the DNA of the patients’ cells in a lab.
Then, the corrected stem cells are returned to patients through what is called an “autologous transplant,” in which they start synthesizing a continuous supply of healthy immune cells that can fight infection.
In the SCID-X1 gene therapy, the corrected stem cells were ultimately cleared by the body but the patients stayed cured of their condition. This research team proposed that the “cure” was down to the aspect that the body could still continuously synthesize newly designed T cells—a crucial part of the body’s immune system.
The researchers employed sophisticated gene tracking technology and several tests to offer unparalleled insights into the T cells in SCID-X1 patients several decades following gene therapy.
The researchers are confident that this gene therapy has led to the perfect conditions for the human thymus (the body part where T cells form) to present a long-term store of the correct type of progenitor cells with the ability to produce new T cells.
More analyses into how this occurs and how it can be leveraged could be highly significant to develop next-generation gene therapy and cancer immunotherapy strategies.
Izotova, N., et al. (2020) Long-term lymphoid progenitors independently sustain naïve T and NK cell production in humans. Nature Communications. doi.org/10.1038/s41467-021-21834-9.