Using induced pluripotent stem cells derived neurons to model brain diseases

Abstract

The ability to use induced pluripotent stem cells (iPSC) to model brain diseases is a powerful tool for unraveling mechanistic alterations in these disorders. Rodent models of brain diseases have spurred understanding of pathology but the concern arises that they may not recapitulate the full spectrum of neuron disruptions associated with human neuropathology. iPSC derived neurons, or other neural cell types, provide the ability to access pathology in cells derived directly from a patient's blood sample or skin biopsy where availability of brain tissue is limiting. Thus, utilization of iPSC to study brain diseases provides an unlimited resource for disease modelling but may also be used for drug screening for effective therapies and may potentially be used to regenerate aged or damaged cells in the future. Many brain diseases across the spectrum of neurodevelopment, neurodegenerative and neuropsychiatric are being approached by iPSC models. The goal of an iPSC based disease model is to identify a cellular phenotype that discriminates the disease-bearing cells from the control cells. In this mini-review, the importance of iPSC cell models validated for pluripotency, germline competency and function assessments is discussed. Selected examples for the variety of brain diseases that are being approached by iPSC technology to discover or establish the molecular basis of the neuropathology are discussed.

Keywords: brain diseases; induced pluripotent stem cells; molecular mechanisms; neuron cell models; therapeutics; translational medicine.

Figure 1

Characterizing induced pluripotent stem cells (iPSC) clones reprogrammed from patient fibroblasts. (A) It is important to verify high quality iPSC clones by morphology (phase) and the expression of pluripotency biomarkers. (B) SOX2 is a nuclear transcription factor and (C) TRA1-81 is a cell surface marker. (D) Beta-tubulin III confirms the ability of the iPSC line to differentiate to neuroectoderm (mesoderm and endoderm markers not shown). All photos are 10× and sourced from the McKinney Lab. GD2: Gaucher type 2; SOX2: sex determining region Y-box 2; TRA1-81: tumor rejection antigen 1-81.

Figure 2

Characterization of Gaucher type 2 (GD2) neurons by biomarkers and functional analysis. (A) Patient derived induced pluripotent stems (iPSC) differentiated to GD2 neurons using defined medium. (B) GD2 neurons express the reporter enhanced green fluorescent protein (EGFP) from a brain specific promoter (human synapsin) delivered by lentivirus. (C) GD2 neuron Patch-clamp analysis shows voltage sensitive Na⁺ channels (arrow) in voltage clamp mode and (D) Multi-Electrode Array (MEA) analysis of GD2 neurons show a burst response at an electrode. Neurons are 32 days in culture after differentiation. These types of analysis confirm active neurons and the cells can be investigated for selected cellular functions.