Biology subjects

Raffa, V.

Publications and source records attributed to Raffa, V..

7 recordsLinked to original sources

bioRxiv2025

The extremely low mechanical force generated by nano-pulling induces global changes in the microtubule network, nuclear morphology, and chromatin transcription in neurons

Mechanical force plays a pivotal role in every aspect of axon development. In this paper, we explore the use of nano-pulling, a technology that enables the intracellular generation of extremely low mechanical forces. We demonstrate that force-mediated axon growth also exerts global effects that extend to the nuclear level. Our mechanistic studies support a model in which exogenous forces induce stabilization of microtubules, and a significant remodeling of perinuclear microtubules, which preferentially align perpendicularly to the nuclear envelope. We observed an increase in the lateral tension of the nucleus, leading to substantial remodelling of nuclear morphology, characterized by an increase in nuclear grooves and higher sphericity index (indicating less flattened nuclei). Notably, these changes in nuclear shape are linked to chromatin remodelling, resulting in global transcriptional activation.

neuroscience↗

bioRxiv2024

A Transfection-Free Approach of Gene Editing via a gold-based nanoformulation of the Cas9 protein

In recent years, the CRISPR/Cas9 technology has emerged as a highly efficient tool for cell gene editing. However, the delivery of the CRISPR/Cas9 system into cells remains a significant challenge, drastically limiting in vivo gene therapy applications. In this study, we present a transfection/transduction-free tool for intracellular delivery of the Cas9:gRNA ribonucleoprotein. The Cas9 enzyme is conjugated to a 12 nm gold nanoparticle through affinity binding between the 6x His-tag of the protein and the NTA-Ni{superscript 2}LJ groups on the nanoparticles. This link chemistry allows a fine control of the density of the enzymes decorating the particle surface, the orientation of the bonding and the stability of the interaction. Importantly, the surface chemistry of this nanoformulation has been precisely engineered to modulate the cellular internalization and localization. Thanks to this approach of precision chemistry, this nanoformulation demonstrated the ability to spontaneously enter human melanoma cells as monodispersed particles that localize in cell cytoplasm, endosomes, and nucleus. It also shows effective gene editing efficiency similarly to conventional transfection tools. This gold-based formulation of Cas9 represents a ready-to-use biotech editing tool, and a promising solution for direct in vivo gene editing applications.

molecular biology↗

bioRxiv2024

A photo-switchable gold nanoformulation based on the dCas9 protein for spatiotemporal controlled gene editing activation in vivo

Genome editing allows for the manipulation of genomic DNA for biotechnology and biomedical applications, but the specificity and control of the editing process remain a challenge. This study introduces a nano-switch for spatiotemporal control of the editing process. The basic module of the nano-switch (the monomer) is composed of a gold nanorod conjugated with the dead Cas9. Based on mathematical models, we established the design and the mechanism of action of the nano-switch. Briefly, when two monomers, guided by their respective guide RNAs, form a dimer onto the DNA and get irradiated with a Near-Infrared pulsed laser resonant at the plasmonic properties of the dimer, they generate a localized heat that triggers a thermal break onto the DNA. The nano-switch was generated, validated, and tested in zebrafish embryos at the 1-cell stage. Molecular analysis of irradiated embryos showed targeted DNA mutations, validating the efficacy of the nano-switch as a tool for conditional gene editing that integrates the if-when-where functions.

molecular biology↗

bioRxiv2023

Nano-pulling stimulates axon regeneration in dorsal root ganglia by inducing stabilization of axonal microtubules and activation of local translation

Axonal plasticity is a phenomenon strongly related to neuronal development as well as regeneration. Recently, it has been demonstrated that active mechanical tension, intended as an extrinsic factor, is a valid contribution to the modulation of axonal plasticity. In previous publications, our team validated a method, the "nano-pulling", for applying mechanical forces on developing axons of isolated primary neurons using magnetic nanoparticles (MNP) actuated by static magnetic fields. This method was found to promote axon growth and synaptic maturation. Here, we explore the possibility to use nano-pulling as an extrinsic factor to promote axon regeneration in a neuronal tissue explant. Having this in mind, whole dorsal root ganglia (DRG) have been dissected from mouse spinal cord, incubated with MNPs, and then stretched. We found that particles were able to penetrate the ganglion and to localise both into the somas and in sprouting axons. Our results point that the nano-pulling doubles the regeneration rate, documented by an increase in the arborizing capacity of axons, and an accumulation of cellular organelles related to mass addition (endoplasmic reticulum and mitochondria) with respect to spontaneous regeneration. In line with the previous results on isolated hippocampal neurons, we observed an increase in the density of stable microtubules and activation of local translation in stretched ganglions. The collected data demonstrate that the nano-pulling is able to enhance axon regeneration in whole spinal ganglia exposed to MNPs and external magnetic fields. The preliminary data represent an encouraging starting point for proposing the nano-pulling as biophysical tool to design novel therapies based on the use of force as an extrinsic factor for promoting nerve regeneration.

neuroscience↗

bioRxiv2022

Low forces push the maturation of neural precursors into neurons

Mechanical stimulation modulates neural development and neuronal activity. In a previous study, we proposed magnetic "nano-pulling" as a tool to generate active forces. By loading neural cells with magnetic nanoparticles (MNPs), a precise force vector is remotely generated through static magnetic fields. In the present study, human neural stem cells (NSCs) were subjected to a standard differentiation protocol, in the presence or absence of nano-pulling. Under mechanical stimulation, we found an increase in the length of the neural processes which showed an enrichment in microtubules, endoplasmic reticulum, and mitochondria. A stimulation lasting up to 52 days induced a strong remodelling at the level of synapse density and a re-organization of the neuronal network, halving the time required for the maturation of neural precursors into neurons. We then injected the MNP-loaded NSCs into mouse spinal cord slices, demonstrating that nano-pulling stimulates the elongation of the NPC processes and modulates their orientation even in an ex vivo model system. To the best of our knowledge, this is the first evidence showing that active mechanical stimuli can guide the outgrowth of NSCs transplanted into the spinal cord tissue. Our findings suggest that MNPs play an important role in neuronal maturation which could be applied in regenerative medicine.

neuroscience↗

bioRxiv2022

Axonal plasticity in response to active forces generated through magnetic nano-pulling

Mechanical force is crucial in guiding axon outgrowth, before and after synapse formation. This process is referred to as "stretch-growth". However, how neurons transduce mechanical inputs into signaling pathways remains poorly understood. Another open question is how stretch-growth is coupled in time with the intercalated addition of new mass along the entire axon. Here, we demonstrate that active mechanical force generated by magnetic nano-pulling induces a remodeling of the axonal cytoskeleton. Specifically, the increase in the axonal density of microtubules leads to an accumulation of organelles and signaling vesicles which, in turn, promotes local translation by increasing the probability of assembly of the "translation factories". The modulation of axonal transport and local translation sustains enhanced axon outgrowth and synapse maturation.

neuroscience↗

bioRxiv2019

A model of Zebrafish Avatar for co-clinical trials

Animal Avatars and co-clinical trials represent an emerging concept for implementing schemes of personalized medicine in oncology. In a co-clinical trial, the cancer cells of the patient tumor are xenotransplanted in the animal Avatar for drug efficacy studies and data collected in the animal trial are used to plan the best drug treatment in the patient trial. Recently, zebrafish has been proposed for implementing Avatar models but the lack of a general criterion for chemotherapy dose conversion from humans to fishes represents a limitation for conducting co-clinical trials.\n\nHere, we validate a simple, reliant and cost-effective Avatar model based on the use of zebrafish larvae; by crossing data from safety and efficacy studies, we found a basic formula for the estimation of the dose to be used for running co-clinical trials and we validate it in a clinical study enrolling 24 adult patients with solid cancers (XenoZ, NCT03668418).

cancer biology↗