Ansari, T. | Search bioRxiv

bioRxiv2021

Self-Assembling Peptide Hydrogels - PeptiGels(R) as a Platform for Hepatic Organoid Culture

A major challenge in advancing preclinical studies is the lack of robust in vitro culture systems that fully recapitulate the in vivo scenario together with limited clinical translational to humans. Organoids, as 3-dimensional (3D) self-replicating structures are increasingly being shown as powerful models for ex vivo experimentation in the field of regenerative medicine and drug discovery. Organoid formation requires the use of extracellular matrix (ECM) components to provide a 3D platform. However, the most commonly used ECM, essential for maintaining organoid growth is Matrigel and is derived from a tumorigenic source which limits its translational ability. PeptiGels(R) which are self-assembling peptide hydrogels present as alternatives to traditional ECM for use in 3D culture systems. Synthetic PeptiGels(R) are non-toxic, biocompatible, biodegradable and can be tuneable to simulate different tissue microenvironments. In this study, we validated the use of different types of PeptiGels(R) for porcine hepatic organoid growth. Hepatic organoids were assessed morphologically and using molecular techniques to determine the optimum PeptiGel(R) formulation. The outcome clearly demonstrated the ability of PeptiGel(R) to support organoid growth and offer themselves as a technological platform for 3D cultured physiologically and clinically relevant data.

bioengineering↗

bioRxiv2017

Prefrontal cortex regulates amygdala response to threat in trait anxiety

BackgroundHighly co-morbid mood and anxiety disorders are associated with aberrant fronto-limbic signalling during emotional processing. Animal models suggest that hypoactive prefrontal cortex weakens top-down control of limbic structures, causing heightened limbic and behavioural reactivity to negative information. Here we tested for this causal mechanism in human trait anxiety. We reasoned that if dorsolateral prefrontal cortex controls amygdala response to affective information, then stimulation of that brain region should reduce the hyperactive amygdala threat responsivity seen in trait anxiety.\n\nMethodsUsing a within-subjects design, sixteen high-trait anxious females received active and sham transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex, in counterbalanced order, with sessions timed to be at least one month apart. Each session was followed immediately by a functional magnetic resonance imaging (fMRI) scan during which participants performed an attentional task with threat-related distractors.\n\nResultsAs predicted, compared to sham stimulation, active prefrontal cortex stimulation reduced amygdala threat reactivity and simultaneously increased activity in cortical regions associated with attentional control and improved task accuracy.\n\nConclusionsThese results demonstrate a causal role for impoverished frontal regulation of amygdaloid function in attentional capture by threat in trait anxiety. The finding that prefrontal stimulation reduces amygdala threat reactivity acutely indicates a neurocognitive mechanism that could contribute to tDCS treatment effects in affective disorders.

neuroscience↗