Genetic changes in the aspartoacylase (ASPA) gene cause the rare, deadly leukodystrophy known as Canavan disease (CD).[1] The metabolic enzyme known as the ASPA protein is primarily expressed in oligodendrocytes.[2] N-acetyl-aspartate (NAA), a tiny molecule (an amino acid) with a molecular weight of only 174.2 Da, is the primary source of the ASPA substrate. It is one of the brain’s most numerous and concentrated metabolites.
To keep the concentration of NAA in the brain at a biologically appropriate level, the NAA produced by neurons can be transported to oligodendrocytes and digested by the oligodendrocyte ASPA enzyme. Researchers at Town of Hope have created universal donor stem cells that one day may be used to treat patients with degenerative diseases like Alzheimer’s and multiple sclerosis and youngsters with fatal brain problems like Canavan disease. This study was published in Advanced Science.
Yanhong Shi, Ph.D., chair of the Department of Neurodegenerative Diseases and the Herbert Horvitz Professor in Neuroscience at the Beckman Research Institute of City of Hope, stated that the strategy that the City of Hope is taking is easily expandable to enhance the standard of life of those with cancer who have developed cognitive impairment or impaired movement as an adverse effect of chemotherapy or radiation. For over 12 years, Shi worked on this project.
According to Shi, this is the initial instance of stem cells being created to serve as universal donors for cell therapies aimed at treating central nervous system illnesses. This “off-the-shelf” strategy can deliver life-saving medicines three to six months earlier to patients who require cell therapy.
Shi and her team converted healthy human skin cells with the aspartoacylase (ASPA) gene functionally into induced pluripotent stem cells (iPSCs). Then they distinguished the iPSCs into oligodendroglial progenitor cells, precursors of cells that generate myelin, an insulating sheath surrounding nerve fibers. Myelin sheaths let information travel through neuronal axons at light speed, much like a bullet train.
The brain accumulation of the toxic metabolite N-acetyl-L-aspartate (NAA) was reduced in the treated animal models of Canavan illness, and they exhibited higher ASPA activity than the control mice. Impaired motor function, mental deficits, and early death have all been associated with excessive NAA use. The outcome was that the treated mice had significantly better motor performance and more myelination. Moreover, the recipient mice’s immune system could not assault the universal donor cells.
This new approach used methods that enabled designed hypoimmunogenic cells obtained from healthy donors to be transferred into a humanized disease model without the immune system activating to kill the foreign therapeutic. In the previous method, her team developed a cell treatment from a patient’s cells to prevent immune rejection.
