A human stem cell model of development and pathology of basal forebrain cholinergic neurons

Abstract

AbstractBackgroundBasal forebrain cholinergic neurons (BFCNs) in the nucleus basalis regulate attention, memory, learning and processing of information related to cognitive function throughout the lifespan. Degeneration of BFCNs is strongly correlated with cognitive function and degeneration of the BFCN projection system is an early event in Alzheimer’s disease (AD) pathogenesis and in Down syndrome (DS, trisomy 21) that is characterized by intellectual impairment at birth and AD pathology in middle age. Understanding the vulnerability of BFCN neurons will help us understand the underlying mechanisms of neurodegeneration in both AD and DS.MethodWe generated BFCNs from trisomy 21 induced pluripotent stem cells (iPSCs) and isogenic controls through addition of morphogens and growth factors following developmental principles. The efficiency of the protocol was assessed through immunofluorescence for choline acetyl transferase (ChAT).ResultWe established a protocol to generate BFCNs from control and trisomy 21 iPSCs through a stepwise process of 1) ventralization of neural progenitors with SHH or SHH agonist, 2) regulation of LHX8 expression with NGF and, 3) regulation of ISLET1 expression and BFCN survival with BMP9. The protocol generated approximately 60% BFCNs from both trisomy 21 and control iPSCs.ConclusionFew differentiation protocols have been established to derive BFCNs from iPSCs. Our iPSC model enables analysis of pathological markers, identification of disrupted molecular pathways, manipulation of conditions to affect neurodegeneration and screening of potential therapeutics in human BFCNs.