ABSTRACT
A microfluidic device for investigating biomolecular cascades between different CNS cell populations
1 Neuro-Zone s.r.l., viale Ortles 22/4, Milano, Italy
2IBM Research GmbH, Zurich Research Laboratory, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
3 Dept. of Pharmacology, CNR Institute of Neuroscience, Univ. of Milano and Fondazione Filarete, Milano, Italy
In the last few years, it has become clear that dysfunctions of the synapse (the functional contact between neurons) are
central to the etiology and progression of a wide range of neurological and psychiatric disorders, including neurodegenerative diseases, schizophrenia, autism, depression, and many others, which can therefore be collectively regarded as synaptopathies. Besides specific defects in neuronal proteins, activation of immune mechanisms and inflammation play a crucial role in synaptopathies. Bidirectional functional interactions among neurons, astrocytes, and microglia, through the release of soluble chemical mediators, govern both the sequence of inflammatory events and the pathological outcome, i.e. damage or absence of damage to the neurons. However, the pathways of these inflammatory signaling cascades remain cryptic and, in particular, the sequential flux of molecular information among the different cell types is frequently undefined. Microfluidics have a huge potential in biomedical research, in particular for studying interactions among cell populations that are involved in complex diseases. Here, we present “overflow” microfluidic networks (oMFNs) made of poly(dimethylsiloxane) (PDMS) for depositing, culturing, and studying cell populations, which are plated in a few microliters of cell suspensions in one or several open cell chambers inside the chip and subsequently cultured for several days in vitro (DIV). After the cells have developed their phenotype, the oMFN is closed with a lid bearing microfluidic connections. Astrocytes, microglia and neurons are grown as homogeneous cultures in separate microcompartments, which can be selectively treated with pharmacological stimuli. The compartments are subsequently connected to each other using microfluidic cover chips, such as to form a network of unidirectionally interconnected microchambers - a concept termed “microfluidic brain chip” (MBC) (Lovchik et al., 2009, 2010a and b). Here, we use a two-chamber oMFN to show that the treatment with beta amyloid and IL-1beta is not toxic to neurons when applied directly to them. The same treatment induces instead neurodegeneration if the stimuli are applied to the astrocyte-containing chamber, which is in microfluidic connection with the neuron-containing one . These data indicate that factors released by astrocytes upon beta amyloid and IL-1beta treatment are toxic to neurons and validate oMFNs as useful tools for dissecting the specific intercellular pathways involved in neurodegenerative and neuroinflammatory brain diseases.
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