Gaucher disease is a rare genetic disorder caused by mutations in a gene called GBA, which encodes for an enzyme that is critical for removing cellular wastes called glucocerebrosides. Mutations in this gene cause the enzyme to be made incorrectly, and glucocerebrosides to build up to toxic levels within cells.
There currently is no cure for Gaucher disease, but there are treatments to manage some of the symptoms. Experimental treatments also are being investigated in an attempt to better treat, or seek a cure for, the disease.
How stem cell therapy works in Gaucher disease
Stem cell therapy is an experimental therapy approach.
For the therapy, a patient’s own cells are first harvested with a skin biopsy or a blood draw. The harvested cells are then processed in a laboratory to convert them to stem cells that can become any type of cell. These stem cells are treated with gene therapy to introduce a healthy copy of the GBA gene in them. After the patient’s bone marrow is irradiated to remove all of the hematopoietic stem cells, which still contain the mutation, the corrected cells are injected into the patient’s bloodstream.
Because these cells are the patient’s own, they can be returned to the body without being rejected by the immune system, which can be the case when donor cells are used. The injected cells migrate to the bone marrow and reseed or replace the bone marrow cell population. It is hoped that the new cells will turn into blood cells able to produce normal GBA enzyme.
Drawbacks of stem cell therapy
This type of stem cell therapy is still in its infancy, especially for Gaucher disease. The process of producing corrected cells for transplant into the patient can take months, and the process of irradiating the bone marrow destroys the patient’s immune system for several weeks to months following the procedure, making them vulnerable to disease. Consequently, stem cell therapy for Gaucher disease is considered only in severe cases that have not responded to other treatments.
Stem cell therapy research in Gaucher disease
A preclinical study in a mouse model of Gaucher disease, published in the scientific journal Molecular Genetics and Metabolism, indicated that stem cell therapy could improve symptoms of certain types of Gaucher disease.
A Cochrane Library review of current literature and clinical trials has indicated that no large-scale clinical trials have been carried out to establish the effect of stem cell therapy in combination with enzyme replacement therapy (ERT), or substrate reduction therapy (SRT) compared to the effect of these two treatments alone.
Some small Phase 1 clinical trials testing stem cell treatment in Gaucher disease have been undertaken (NCT00004294, NCT00001234), but the results have not been published yet.
***