Publications

JTD Keywords: biochemical engineering, neurotrauma and neurodegenerative disease, optogenetics and dreadds, spinal cord injury (sci), Biochemical engineering, Neurotrauma and neurodegenerative disease, Optogenetics and dreadds, Sensorimotor, Spinal cord injury (sci)

Over the most recent decades, the development of new biological platforms to study disease progression and drug efficacy has been of great interest due to the high increase in the rate of neurodegenerative diseases (NDDs). Therefore, blood-brain barrier (BBB) as an organ-on-a-chip (OoC) platform to mimic brain-barrier performance could offer a deeper understanding of NDDs as well as a very valuable tool for drug permeability testing for new treatments. A very attractive improvement of BBB-oC technology is the integration of detection systems to provide continuous monitoring of biomarkers in real time and a fully automated analysis of drug permeably, rendering more efficient platforms for commercialization. In this Perspective, an overview of the main BBB-oC configurations is introduced and a critical vision of the BBB-oC platforms integrating electronic read out systems is detailed, indicating the strengths and weaknesses of current devices, proposing the great potential for biosensors integration in BBB-oC. In this direction, we name potential biomarkers to monitor the evolution of NDDs related to the BBB and/or drug cytotoxicity using biosensor technology in BBB-oC.

JTD Keywords: Bbb, Biosensors, Blood-brain barrier (bbb), Electrical-resistance, Electrochemical biosensors, Endothelial-cells, In-vitro model, Matrix metalloproteinases, Mechanisms, Neurodegenerative diseases (ndds), Organ-on-a-chip (ooc), Permeability, Stress, Transendothelial electrical resistance (teer), Transepithelial, Transport

Many neurodegenerative disorders display protein aggregation as a hallmark, Huntingtin and TDP-43 aggregates being characteristic of Huntington disease and amyotrophic lateral sclerosis, respectively. However, whether these aggregates cause the diseases, are secondary by-products, or even have protective effects, is a matter of debate. Mutations in both human proteins can modulate the structure, number and type of aggregates, as well as their toxicity. To study the role of protein aggregates in cellular fitness, we have expressed in a highly tractable unicellular model different variants of Huntingtin and TDP-43. They each display specific patterns of aggregation and toxicity, even though in both cases proteins have to be very highly expressed to affect cell fitness. The aggregation properties of Huntingtin, but not of TDP-43, are affected by chaperones such as Hsp104 and the Hsp40 couple Mas5, suggesting that the TDP-43, but not Huntingtin, derivatives have intrinsic aggregation propensity. Importantly, expression of the aggregating form of Huntingtin causes a significant extension of fission yeast lifespan, probably as a consequence of kidnapping chaperones required for maintaining stress responses off. Our study demonstrates that in general these prion-like proteins do not cause toxicity under normal conditions, and in fact they can protect cells through indirect mechanisms which up-regulate cellular defense pathways. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: aggregation, antioxidant, degradation, features, fission yeast, gene, neurodegenerative diseases, pap1, polyglutamine toxicity, protein aggregation, proteins, stress, tdp-43, Amyotrophic-lateral-sclerosis, Chaperone, Chemistry, Dna binding protein, Dna-binding proteins, Fission yeast, Genetics, Human, Humans, Huntingtin, Metabolism, Molecular chaperones, Neurodegenerative diseases, Prion, Prions, Protein aggregate, Protein aggregates, Protein aggregation, Schizosaccharomyces, Tdp-43

Background: Evidence from patients and animal models suggests that obstructive sleep apnea (OSA) may increase the risk of Alzheimer’s disease (AD) and that AD is associated with reduced brain tissue stiffness. Aim: To investigate whether intermittent hypoxia (IH) alters brain cortex tissue stiffness in AD mutant mice exposed to IH mimicking OSA. Methods: Six-eight month old (B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J) AD mutant mice and wild-type (WT) littermates were subjected to IH (21% O2 40 s to 5% O2 20 s; 6 h/day) or normoxia for 8 weeks. After euthanasia, the stiffness (E) of 200-μm brain cortex slices was measured by atomic force microscopy. Results: Two-way ANOVA indicated significant cortical softening and weight increase in AD mice compared to WT littermates, but no significant effects of IH on cortical stiffness and weight were detected. In addition, reduced myelin was apparent in AD (vs. WT), but no significant differences emerged in the cortex extracellular matrix components laminin and glycosaminoglycans when comparing baseline AD and WT mice. Conclusion: AD mutant mice exhibit reduced brain tissue stiffness following both normoxia and IH mimicking sleep apnea, and such differences are commensurate with increased edema and demyelination in AD.

JTD Keywords: Animal model, Atomic force microscopy, Brain mechanics, Cortex stiffness, Neurodegenerative disease

A critical step in the development of effective therapeutics to treat Parkinson's disease (PD) is the identification of molecular pathogenic mechanisms underlying this chronically progressive neurodegenerative disease. However, while animal models have provided valuable information about the molecular basis of PD, the lack of faithful cellular and animal models that recapitulate human pathophysiology is delaying the development of new therapeutics. The reprogramming of somatic cells to induced pluripotent stem cells (iPSC) using delivery of defined combinations of transcription factors is a groundbreaking discovery that opens great opportunities for modeling human diseases, including PD, since iPSC can be generated from patients and differentiated into disease-relevant cell types, which would capture the patients' genetic complexity. Furthermore, human iPSC-derived neuronal models offer unprecedented access to early stages of the disease, allowing the investigation of the events that initiate the pathologic process in PD. Recently, human iPSC-derived neurons from patients with familial and sporadic PD have been generated and importantly they recapitulate some PD-related cell phenotypes, including abnormal α-synuclein accumulation in vitro, and alterations in the autophagy machinery. This review highlights the current PD iPSC-based models and discusses the potential future research directions of this field.

JTD Keywords: Human cellular model, Induced pluripotent stem cells, Neurodegenerative disease, Parkinson's disease

The histopathological hallmarks of Alzheimer disease are the self-aggregation of the amyloid beta peptide (A beta) in extracellular amyloid fibrils and the formation of intraneuronal Tau filaments, but a convincing mechanism connecting both processes has yet to be provided. Here we show that the endogenous polysaccharide chondroitin sulfate B (CSB) promotes the formation of fibrillar structures of the 42-residue fragment, A beta(1-42). Atomic force microscopy visualization, thioflavin T fluorescence, CD measurements, and cell viability assays indicate that CSB-induced fibrils are highly stable entities with abundant beta-sheet structure that have little toxicity for neuroblastoma cells. We propose a wedged cylinder model for A beta(1-42) fibrils that is consistent with the majority of available data, it is an energetically favorable assembly that minimizes the exposure of hydrophobic areas, and it explains why fibrils do not grow in thickness. Fluorescence measurements of the effect of different A beta(1-42) species on Ca2+ homeostasis show that weakly structured nodular fibrils, but not CSB-induced smooth fibrils, trigger a rise in cytosolic Ca2+ that depends on the presence of both extracellular and intracellular stocks. In vitro assays indicate that such transient, local Ca2+ increases can have a direct effect in promoting the formation of Tau filaments similar to those isolated from Alzheimer disease brains.

JTD Keywords: AFM, Alzheimers-disease, Chondroitin sulfate, Heparan-sulfate, Lipid-bilayers, Beta-peptide, In-vitro, Neurodegenerative diseases, Extracellular-matrix, Prion protein