Stem cell culture used to investigate potential new treatment; findings point to new class of drugs
Working with both stem cell cultures and animal models, researchers have succeeded in reducing the production of a defective protein responsible for Huntington’s disease , and t hey did so while leaving levels of the protein’s normal counterpart unchanged — a critical goal in the search for effective treatment for this progressive, fatal disease. The findings were presented November 18 at Neuroscience 2014, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.
Huntington’s disease is a degenerative brain disorder that results from the ongoing destruction of nerve cells in the brain. Afflicted individuals lose their ability to walk, talk, think, and reason. Previously, research in animal models ha s shown that reducing the levels of the defective Htt protein can prevent, or even reverse, Huntington’s disease. However, most methods used previously to lower Htt levels decrease d both the protein’s “good” and “bad” forms.
“Our approach hones in on the defective form of Htt, reducing disease symptoms and laying the groundwork for the development of a new class of drugs to treat Huntington’s,” said senior author Philip Gregory, PhD , senior vice president of research and chief scientific officer of Sangamo BioSciences Inc. in Richmond, California.
The study reports a novel therapeutic approach based on an engineered version of a class of natural proteins called zinc finger protein transcription factors, or ZFP TFs, that control the expression of specific genes. The researchers custom designed a ZFP TF to recognize the defective version of the gene that serves as a template for the dangerous form of the Htt protein. Because most cells in the human body produce Htt, the researchers were able to test the engineered ZFP TF in skin stem cells (fibroblast cells) derived from Huntington’s patients. In these cell cultures, the ZFP TFs lowered the production of mutant Htt by more than 90 percent, while leaving levels of the normal protein unaffected. Importantly, mutant Htt was also reduced in neurons that originated from Huntington’s patient cell cultures, and this reduction reversed several disease - related neuron defects, including their susceptibility to cell death. And in mouse models of Huntington’s disease, ZFP TFs significantly reduced the production of mutant Htt, reversing disease - related motor defects.