Researchers at the Alzheimer’s Association International Conference® 2012 (AAIC®2012) today reported the creation of a new model of Alzheimer’s derived from the skin cells of people with the disease that were reprogramed into Alzheimer’s brain cells.
This new Alzheimer’s model may prove to be more accurate than current mouse models of the disease and therefore can be used (a) to generate important new insights into the biology of Alzheimer’s and related disorders and (b) for early stage testing of new therapies.
“Current animal models of Alzheimer’s are highly engineered to express elements of the disease, and, while valuable for research, incompletely represent how the disease forms and progresses in people,” said William Thies, PhD, Alzheimer’s Association® Chief Medical and Scientific Officer. “In order to develop better therapies and eventually prevent Alzheimer’s, we need better, more accurate animal and cellular models of the disease. This newly reported research is a significant step forward in that direction.”
Most of the current Alzheimer’s mouse models incorporate genetic changes found in familial young-onset forms of Alzheimer’s. Although these mice have taught us about many valuable aspects of the disease, the hallmark amyloid plaques found in the brains of people with Alzheimer’s do not form in the same way as in the brains of mice expressing mutant forms of the most common young-onset Alzheimer’s gene, and significant brain cell death does not occur. New approaches are needed.
Andrew Sproul, PhD, a postdoctoral associate, and colleagues working at The New York Stem Cell Foundation (NYSCF) in the laboratory of Scott Noggle, PhD, the NYSCF-Charles Evans Senior Research Fellow for Alzheimer’s Disease, pursued an induced pluripotent stem cell (iPSC) approach to model Alzheimer’s, and reported their results for the first time today at AAIC 2012. This involves taking cells from people with the disease and their unaffected family members, typically skin cells, and reprogramming them by adding genetic factors. The resulting iPSCs can be used to model Alzheimer’s in a dish.
“One advantage of this technology is that we get a near infinite supply of disease and control patient stem cells,” Sproul said. “Another is that we can then turn the iPSCs into any tissue in the body. This allows us to investigate the role of various cells in Alzheimer’s disease progression by manipulating the iPSCs to form different types of brain cells (forebrain nerve cells, neural stem cells, glial cells) that we and others believe are involved in Alzheimer’s.”
The researchers generated iPSCs from a total of 12 people with Alzheimer’s and healthy controls from two young-onset, genetic Alzheimer’s families. The iPSC lines have been quality-controlled, including ensuring pluripotency, which is the ability to make all kinds of cells from the endoderm (interior stomach lining, gastrointestinal tract, lungs), mesoderm (muscle, bone, blood, urogenital), or ectoderm (skin and nervous system).
“We have made both the control and Alzheimer’s iPSCs into brain cells and have demonstrated that they are electrically active. These new brain cells include forebrain cholinergic neurons, which are particularly vulnerable in Alzheimer’s disease,” Sproul said.
“We have also begun to use the iPSC-derived neurons and neural stem cells to compare differences in cellular function between people with Alzheimer’s and their unaffected relatives. For example, we, in conjunction with Dr. Sam Gandy’s group at Mount Sinai School of Medicine, have demonstrated that Alzheimer’s neurons produce more of the toxic form of beta amyloid, the protein fragment that makes up amyloid plaques, though this aspect of the research is preliminary,” Sproul added.
The research reported at AAIC 2012 focuses on people with presenilin-1 (PSEN1) mutations, which are responsible for the most common form of rare, inherited, young-onset Alzheimer’s (estimated to be less than two percent of total cases). According to Sproul, this work may provide a platform to screen new drugs that could alleviate defects caused by the faulty gene.
However, because the overwhelming majority of people with Alzheimer’s have the late onset “sporadic” form of the disease, the scientists say they plan to expand their research to include large-scale production of iPSCs from people with different types of Alzheimer’s.
“We have begun to extend this work by collaborating with four different institutions in New York City – the Mount Sinai School of Medicine, Columbia University, New York University, and Rockefeller University. Over the next few years, we expect to provide substantial insight into Alzheimer’s and valuable tools to help create the next generation of therapeutics,” Sproul said.
Andrew Sproul, et al. Development of an Induced Pluripotent Stem Cell (iPSC) Alzheimer’s Disease Model Using PSEN1 Mutant Fibroblasts. (Funders: Alzheimer’s Drug Discovery Foundation, New York Community Trust, Charles Evans Foundation)
Development of an Induced Pluripotent Stem Cell (iPSC) Alzheimer’s Disease Model Using PSEN1 Mutant Fibroblasts
Andrew Sproul1, Samson Jacob1, Michael Nestor1, Serene Keilani2, Ying Jean3, Dave Kahler1, Ismael Santa-Maria3, John Steele4, John Crary3, Carol Troy3, Sam Gandy5, Scott Noggle1
1The New York Stem Cell Foundation, New York, New York, United States; 2Mount Sinai School of Medicine, New York, New York, United States; 3Columbia University Medical Center, New York, New York, United States; 4Neurology and Psychiatry and the Alzheimer’s Disease Research Center, and the James J Peters VA Medical Center, Bronx NY, New York, New York, United States; 5Mount Sinai, New York City, New York, United States
Presenting author e-mail: email@example.com
Background: Animal models of genetic forms of AD have not fully recapitulated the human disease. Furthermore, over 95% of subjects with common sporadic forms of Alzheimer’s disease (AD) lack identifiable mutations. Developing an induced pluripotent stem cells (iPSCs) model from AD patient fibroblasts provides the best pathway for studying brain cells from these patients and identifying potentially pathogenic subcellular phenotypes. We have created iPS cells from patients carrying presenilin-1 (PSEN1) mutations, which are responsible for the most common form of autosomal dominant, 100% penetrant, inherited AD. A total of twelve affected and unaffected control patients from the FAD1 (A246E) and FAD4 (M146L) families were used to generate iPS lines. These in turn have been successfully differentiated into human forebrain neurons for use in mechanistic studies of Aβ production, cell death, and other AD-relevant biochemical changes.
Methods: Human fibroblasts were reprogrammed via retroviral addition of the four Yamanaka transcription factors – Oct4, KLF4, Sox2, and c-Myc. iPS lines were analyzed by a variety of methods to characterize pluripotency and retroviral transgene silencing. We have differentiated control and AD iPS cells into forebrain neurons utilizing both embryoid body (EB) and monolayer methods, including generation of cholinergic basal forebrain neurons that are vulnerable in AD.
Results: Initial studies indicate that human iPS neuronal cells can respond to exogenous oligomerized abeta in a similar manner to hippocampal rodent neurons by induction of pro-apoptotic proteins such as Bim. Our preliminary studies suggest substantial biochemical and phenotypic differences between control and AD neuronal cells, including an increased ratio of secreted Aβ42/Aβ40, and enhanced cell death in response to apoptotic stimuli.
Conclusions: We have successfully generated an iPSC model of early-onset AD that reflects multiples aspects of the disease biochemically and phenotypically at the cellular level. The recapitulation of brain molecular phenotypes affirms the promise of this approach and validates our efforts at extending this strategy to the discovery of subcellular phenotypes underlying common sporadic AD. Furthermore, by developing a human in vitro model of cholinergic basal forebrain neurons, we have created a platform that can be used for high throughput screening campaigns to identify novel therapeutics.
Alzheimer’s Association International Conference 2012 (AAIC)®
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