Down syndrome (DS) is the most common genetic origin of intellectual disability and is the single most common risk factor for early-onset Alzheimer’s disease (AD). Also called Trisomy 21, this condition occurs when an individual has 3 copies of human chromosome 21 (HSA21). The additional genetic material causes impairment in cognitive ability and physical growth and is often associated with other complications ranging from cardiac defects to hearing and vision problems. Most physical symptoms of DS can now be treated or alleviated, but there are no effective treatments that improve cognitive function. By the age of 40, people with DS will reliably develop amyloid plaques and neurofibrillary tangles, two pathological hallmarks of AD in the general population and the vast majority will develop AD dementia by their 60s. Therefore, understanding the molecular mechanisms underlying the abnormal brain development and early-onset AD in DS may assist with the development of novel treatments for intellectual disability and AD in this important population as well as for AD in general population.
The advent of induced pluripotent stem cell (iPSC) technology has provided a new approach to the establishment of human cellular models for studying the pathogenesis of neurodevelopmental and neurodegenerative diseases. We have generated human iPSCs directly from DS patients and differentiated them to patients’ own brain cells. Moreover, we have established 2-dimensional (2D) stem cell neural differentiation model, 3D cerebral organoid model as well as in vivo human chimeric mouse brain model to study the disease mechanisms and develop novel therapeutics (Figure 1).
Representative publications (* co-corresponding author; # co-first author):
Jiang, P., Turkalj, L., & Xu, R. (2020). High-Fidelity Modeling of Human Microglia with Pluripotent Stem Cells. Cell Stem Cell, 26, 629-631.
Xu R, Li X, Boreland AJ, Posyton A, Kwan K, Hart RP, Jiang P. Human iPSC-derived mature microglia retain their identity and functionally integrate in the chimeric mouse brain. Nat Commun. 2020 Mar 27;11(1):1577.