Functional Effects of a Neuromelanin Analogue on Dopaminergic Neurons in 3D Cell Culture.

The substantia nigra pars compacta (SNpc) is a discrete region of the brain that exhibits a dark pigment, neuromelanin (NM), a biomaterial with unique properties and the subject of ongoing research pertaining to neurodegenerative conditions like Parkinson's disease (PD). Obtaining human tissue to isolate this pigment is costly and labor intensive, making it necessary to find alternatives to model the biochemical interaction of NM and its implications on PD. To address this limitation, we modified our established silk 3D brain tissue model to emulate key characteristics of the SNpc by using a structural analogue of NM to examine the effects of the material on dopaminergic neurons using Lund's human mesencephalon (LUHMES) cells. We utilized a sepia-melanin, squid ink, derived NM analogue (NM-sim) to chelate ferric iron, and this iron-neuromelanin precipitate (Fe-NM) was purified and characterized. We then exposed LUHMES dopaminergic cells to the NM-sim, Fe-NM-sim, and control vehicle within 3D silk protein scaffolds. The presence of both NM-sim and Fe-NM-sim in the scaffolds negatively impacted spontaneous electrical activity from the LUMES networks, as evidenced by changes in local field potential (LFP) electrophysiological recordings. Furthermore, the Fe-NM-sim precipitate generated peroxides, depleted nutrients/antioxidants, and increased protein oxidation by carbonylation in sustained (>2 weeks) 3D cultures, thereby contributing to cell dysfunction. The results suggest that this 3D tissue engineered brain-like model may provide useful readouts related to PD neuro-toxicology research.

Tutorials for Electrophysiological Recordings in Neuronal Tissue Engineering.

Electrophysiology is a powerful tool to examine cellular functions, but the use of the techniques remains challenging outside of physiology and neuroscience fields. We aim to provide a practical methods guide for electrophysiological recordings to nonexperts in the field to help with the utility of these important research tools. We focus on two techniques that are critical in the context of tissue engineering, whole-cell patch clamp recording for assessing cellular functions and extracellular field potential recording for evaluating network activities. Specific examples are presented to demonstrate how the techniques were applied to tissue engineering studies.

Comparison of muscle functions during three contrasting abdominal exercises.

That different amplitudes of muscle activities during various abdominal exercises not only reflect the inherent differences in motor control but movement speed as well was hypothesized. 20 healthy adults (M age = 23 yr.) performed three exercises that involved varying amounts of trunk control: the partial sit-up, full sit-up, and AbSlide roll. Covariate analyses indicated that the amplitude of muscle activities could be partitioned into three categories: motor control and scaling (speed and amplitude), scaling only, and motor control only. Overall, the AbSlide exercise activated the most amount of muscular activity, followed by the full and partial sit-up exercises. Results are discussed in terms of how the various muscles contribute to motor control and velocity scaling.