Abstract
Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. Humanized disease models are required to develop new therapies for currently incurable forms of AMD.In this work, a tissue-on-a-chip approach was developed through combining human induced pluripotent stem cells, Electric Cell–substrate Impedance Sensing (ECIS) and reproducible electrical wounding assays to model and quantitatively study AMD. Retinal Pigment Epithelium (RPE) cells generated from a patient with an inherited macular degeneration and from an unaffected sibling were used to test the model platform on which a reproducible electrical wounding assay was conducted to model RPE damage. First, a robust and reproducible real-time quantitative monitoring over a 25-day period demonstrated the establishment and maturation of RPE layers on the microelectrode arrays. A spatially controlled RPE layer damage that mimicked cell loss in AMD disease was then initiated. Post recovery, significant differences (P<0.01) in migration rates were found between case (8.6±0.46 μm/h) and control cell lines (10.69±0.21 μm/h). Quantitative data analysis suggested this was achieved due to lower cell–substrate adhesion in the control cell line. The ECIS cell–substrate adhesion parameter (α) was found to be 7.8±0.28 Ω1/2 cm for the case cell line and 6.5±0.15 Ω1/2 cm for the control. These findings were confirmed using cell adhesion biochemical assays. The developed disease model-on-a-chip is a powerful platform for translational studies with considerable potential to investigate novel therapies by enabling real-time, quantitative and reproducible patient-specific RPE cell repair studies.
Highlights
Sub-retinal vascular leakage predominates and dry Age-related Macular Degeneration (AMD) in which deposit formation and cell degeneration are the primary disease processes
Induced pluripotent cells were successfully derived from a patient with late-onset retinal macular degeneration (LORMD) and one unaffected sibling
This study has demonstrated a reproducible and robust tissueon-a-chip approach to quantitatively study a patient-specific retinal macular degeneration disease model
Summary
Sub-retinal vascular leakage predominates and dry AMD in which deposit formation and cell degeneration are the primary disease processes. Recent developments enable the generation of RPE cells derived from patients (hiPSC-RPE) allowing in vitro study of human retinal disease that has greater clinical and physiological relevance (Meyer et al, 2009; Takahashi et al, 2007). Scratching assays does not produce a highly repeatable wound; a disadvantage that can be overcome by stamping These methods can disrupt the ECM layer as well as form debris that might affect the migration process. In order to overcome both cell source and current wounding assays limitations, a tissue-on-a-chip approach was investigated by developing and characterising a human induced pluripotent stem cells model of RPE layer on Electric Cell–substrate Impedance Sensing microelectrode arrays. An electrical wound healing assay was used to mimic RPE cell damage in both control and diseased hiPSC-RPE cell lines to study differences in repair. The disease model-on-a-chip was used to answer a series of questions concerning the role of RPE adhesion in repair pointing towards potential therapeutic strategies
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