With the approval of the FDA Modernization Act 2.0, the pharmaceutical industry is poised to expand its research components with a plethora of alternative models, including organ-on-microfluidic chips in pharma and biotechnology, resulting in a personalized approach. Microfluidics opens new possibilities for the study of cell biology, especially for a better understanding of cell-cell interactions and the pathophysiology of neurodegenerative diseases in vitro and use these models to assess the efficacy of novel therapies. These thumb-sized organ-on-a-chip systems have the potential to reduce animal testing and replace simple 2D culture systems. Restoring critical aspects of endothelial-brain immune cell communication in a biomimetic system using microfluidics may accelerate the process of central nervous system (CNS) drug discovery and improve our understanding of the mechanisms of multiple neurodegenerative diseases. These organ-on-chip technologies can be used to optimize drug targets and assess drug efficacy and toxicity in real-time, which can significantly help minimize animal testing requirements, as authorized by the recent FDA Act. Recent advances in modeling cell-to-cell communication in the CNS are described in this review. This Review initially summarizes the fundamental advantages of microfluidic systems in creating a compartmentalized cell culture for the complex three-dimensional architectures of neural tissue cells such as neurons, glial cells, and endothelial cells, and their recapitulation of spatiotemporal biophysicochemical gradients and mechanical microenvironments. Brain endothelial cell-astroglia-on-a-chip models with a focus on neurodegenerative diseases such Alzheimer's disease, Parkinson's disease, and Huntington's disease and amyotrophic lateral sclerosis is introduced. Then, the current limitations of these microfluidic devices and strategies to overcome them are discussed.

: The interaction of the Activating Transcription Factor 6 (ATF6), a key effector of the unfolded protein response (UPR) in the endoplasmic reticulum, with the neuronal calcium sensor Downstream Regulatory Element Antagonist Modulator (DREAM) is a potential therapeutic target in neurodegeneration. Modulation of the interaction ATF6-DREAM with repaglinide (RP) induced neuroprotection in a model of Huntington´s disease. Amyotrophic Lateral Sclerosis (ALS) is a neurodegenerative disorder with no cure, characterized by the progressive loss of motoneurons resulting in muscle denervation, atrophy, paralysis and death. The aim of this work was to investigate the potential therapeutic significance of DREAM as a target for intervention in ALS. We found that the expression of the DREAM protein was reduced in the spinal cord of SOD1G93A mice compared to wild type littermates. RP treatment improved motor strength and reduced the expression of the ALS progression marker collagen type XIX1 (Col191 mRNA) in the quadriceps muscle in SOD1G93A mice. Moreover, treated SOD1G93A mice showed reduced motoneuron loss and glial activation and increased ATF6 processing in the spinal cord. These results indicate that the modulation of the DREAM-ATF6 interaction ameliorates ALS symptoms in SOD1G93A mice.

Parkinson’s disease (PD) is a progressive neurodegenerative disease characterized by resting tremor, bradykinesia, rigidity, postural instability, that also includes non-motor symptoms such as mood dysregulation. Dopamine (DA) is the primary neurotransmitter involved in this disease, but cholinergic imbalance has also been implicated. Current intervention in PD is focused on replenishing central DA, which provides remarkable temporary symptomatic relief but does not address the neuronal loss and the progression of the disease. It has been well established that neuronal nicotinic cholinergic receptors (nAChRs) can regulate DA release and that nicotine itself may have neuroprotective effects. Recent studies have identified nAChRs in nonneuronal cell types including glial cells, where they may regulate inflammatory responses. Given the crucial role of neuroinflammation in dopaminergic degeneration, and the involvement of microglia and astrocytes in this response, glial nAChRs may provide a novel therapeutic target in prevention and/or treatment of PD. In this review, following a brief discussion of PD, we focus on the role of glial cells and specifically their nAChRs in PD pathology and/or treatment.