A microfluidic approach to rescue ALS motor neuron degeneration using rapamycin.

TAR DNA-binding protein-43 (TDP-43) is known to accumulate in ubiquitinated inclusions of amyotrophic lateral sclerosis affected motor neurons, resulting in motor neuron degeneration, loss of motor functions, and eventually death. Rapamycin, an mTOR inhibitor and a commonly used immunosuppressive drug, has been shown to increase the survivability of Amyotrophic Lateral Sclerosis (ALS) affected motor neurons. Here we present a transgenic, TDP-43-A315T, mouse model expressing an ALS phenotype and demonstrate the presence of ubiquitinated cytoplasmic TDP-43 aggregates with > 80% cell death by 28 days post differentiation in vitro. Embryonic stem cells from this mouse model were used to study the onset, progression, and therapeutic remediation of TDP-43 aggregates using a novel microfluidic rapamycin concentration gradient generator. Results using a microfluidic device show that ALS affected motor neuron survival can be increased by 40.44% in a rapamycin dosage range between 0.4-1.0 µM.

Development-on-chip: in vitro neural tube patterning with a microfluidic device.

Embryogenesis is a highly regulated process in which the precise spatial and temporal release of soluble cues directs differentiation of multipotent stem cells into discrete populations of specialized adult cell types. In the spinal cord, neural progenitor cells are directed to differentiate into adult neurons through the action of mediators released from nearby organizing centers, such as the floor plate and paraxial mesoderm. These signals combine to create spatiotemporal diffusional landscapes that precisely regulate the development of the central nervous system (CNS). Currently, in vivo and ex vivo studies of these signaling factors present some inherent ambiguity. In vitro methods are preferred for their enhanced experimental clarity but often lack the technical sophistication required for biological realism. In this article, we present a versatile microfluidic platform capable of mimicking the spatial and temporal chemical environments found in vivo during neural tube development. Simultaneous opposing and/or orthogonal gradients of developmental morphogens can be maintained, resulting in neural tube patterning analogous to that observed in vivo.