Biology subjects

Filippi, M.

Publications and source records attributed to Filippi, M..

11 recordsLinked to original sources

bioRxiv2026

3D Human Neuromuscular Architecture Encoded by Compliant Patterned Hydrogel Scaffolds

Engineered human neuromuscular models are limited by a trade-off between biological fidelity and architectural control: self-assembled organoids organize stochastically, while engineered 3D tissues impose anisotropy through passive tension at the edges without internal guidance. Here we encode architectural guidance into human neuromuscular tissues by coupling a three-dimensional, cell-laden biomatrix to a xolographically printed hydrogel substrate featuring sub-millimeter surface topography. We demonstrate that grooved substrates increase human primary myotube alignment and maturation in the overlying 3D tissue, while guiding directional axon extension from human iPSC-derived motor neuron spheroids. We show that combining both cell types along a shared alignment axis establishes functional neuromuscular connectivity, evidenced by acetylcholine receptor clustering, glutamate-evoked contraction and its blockade by d-tubocurarine (curare), and yields innervation coverage of centimeter scale tissues. Overall, this platform combines compliant substrates, mesoscale tissue architectural guidance, and human-relevant cell biology in a single untethered construct for studies of neuromuscular tissue development and function.

bioengineering↗

bioRxiv2026

Cell-Dense Bioink Design for Xolography: Coupling Refractive Index-Matching with Increased Photoreactivity

Bioxolography enables high-resolution fabrication of geometrically complex, cell-laden constructs for tissue engineering. However, tissue-relevant cell densities conflict with the optical transparency required for efficient dual-color volumetric printing. In this work, we extend the Bioxolography toolbox to include refractive index (RI) matching for cell-laden bioresins using iodixanol (IDX). Remarkably, IDX enhances optical transparency and boosts reactivity -- a phenomenon unique to Xolography. Yet, excessive IDX compromises dual-color efficiency through increased absorption and undesired UV-only curing, underscoring a central trade-off between optical clarity and photochemical performance. Systematic tuning of resin compositions along an iso-refractive index line demonstrated the versatility of Bioxolography, with IDX enhancing polymerization and 4-Hydroxy-TEMPO providing biocompatible inhibition. Optimizing composition and printing parameters yielded GelMA hydrogels with cell densities up to 5{middle dot}106 cells{middle dot}mL-1. Cell-laden prints achieved sub-100 {micro}m resolution and complex geometries such as channels and gyroids. Using skeletal muscle tissue as a model, we validated RI matched Bioxolography as a promising strategy for tissue engineering by demonstrating cell alignment along printed grooves and formation of mature muscle fibers characterized by MyoHC+ staining and fusion index. By integrating physical, chemical, and biological perspectives, this work advances Xolography toward biomaterials development and reinforces its position as an emerging volumetric (bio)printing technology. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/729865v1_ufig1.gif" ALT="Figure 1"> View larger version (86K): org.highwire.dtl.DTLVardef@19c0380org.highwire.dtl.DTLVardef@1a9e920org.highwire.dtl.DTLVardef@84210org.highwire.dtl.DTLVardef@294112_HPS_FORMAT_FIGEXP M_FIG C_FIG For printing higher cell density bioresins with Xolography, iodixanol (IDX) is added for refractive index-matching. The addition leads to an unexpected additional effect with increased reactivity in the dual-color photopolymerization. With careful adjustment of the resin composition and the printing parameters, Bioxolography is proven as a viable tool for tissue engineering.

bioengineering↗

bioRxiv2026

A Virtual Reality Dataset to Support Hand Action Observation in Rehabilitation and Motor Learning Studies

The recovery of motor function is increasingly understood as a process influenced not only by physical training but also by perceptual and cognitive strategies. Action Observation Treatment (AOT), a neurorehabilitation approach in which patients observe goal-directed motor actions before executing them, has demonstrated clinical benefits; however, its wider implementation is hindered by a lack of standardized procedures. We present an open-access dataset of 33 upper limb gestures specifically developed to support the administration of Virtual Reality-based AOT (VR-AOT). The gestures were selected in collaboration with expert physiotherapists to ensure clinical relevance, and are provided as motion capture recordings along with Unity-based 3D animations embedded in configurable virtual scenes. The dataset is designed for flexibility, allowing users to modify parameters such as viewpoint, laterality, and repetition count. Technical validation confirms its usability and therapeutic applicability across multiple clinical and research contexts. This dataset offers a standardized yet customizable resource for developing and comparing VR-AOT protocols, with potential applications in neurorehabilitation and motor learning research.

neuroscience↗

bioRxiv2024

Bilayered Biofabrication Unlocks the Potential of Skeletal Muscle for Biohybrid Soft Robots

The emerging field of biohybrid robotics aims to create the next generation of soft and sustainable robots by using engineered biological muscle tissues integrated with soft materials as artificial muscles (bio-actuators). Both cardiac and skeletal muscle cells can be used for biohybrid actuation. Generally, cardiac bio-actuators take the shape of thin cellular films, while locomotive skeletal muscle bio-actuators form bulk tissues. The geometry of a bio-actuator should be optimized for the type of desired motion, e.g., thin film layers are optimal for swimming actuators mimicking fish. Until now, the geometry of skeletal muscle bio-actuators has been constrained to ring- or block-like tissues generally differentiated around a pair of pillars due to the need to oppose the contraction force exerted during the skeletal muscle differentiation process. In this work, we extend the possible geometry of skeletal muscle bio-actuators by demonstrating a bilayered design that mimics the motion of jellyfish. We take advantage of a volumetric printing method, i.e., xolography, which allows us to micropattern poly(ethylene glycol) diacrylate and gelatin methacrylate hydrogels to serve as scaffolds for seeding a layer of the skeletal muscle cell matrix. We demonstrate the locomotion speed of our bio-actuators is 3.4x faster than previously reported counterparts. In addition, our skeletal bio-actuators outperform most cardiac ones. Further optimization of our bilayer biofabrication for improved reproducibility of the maturation process of the skeletal muscle tissue will pave the way for the next generation of performant skeletal muscle-based actuators for biohybrid robots.

bioengineering↗

bioRxiv2024

Integrated Closed-loop Control of Bio-actuation for Proprioceptive Bio-hybrid Robots

Biohybrid robots are emergent soft robots that combine engineered artificial structures and living biosystems to exploit unique characteristics of biological cells and tissues. Skeletal muscle tissue-based bio-actuators can respond to externally applied stimuli, such as electrical fields. However, current bio-actuation systems rely on open-loop control strategies that lack knowledge of the actuators state. The regulation of output force and position of bio-hybrid robots requires self-sensing control systems that combine bio-actuators with sensors and control paradigms. Here, we propose a soft, fiber-shaped mechanical sensor based on a composite with piezoresistive properties that efficiently integrates with engineered skeletal muscle tissue and senses its contracting states in a cell culture environment in the presence of applied electrical fields. After testing the sensors insulation and biocompatibility, we characterized its sensitivity for typical strains (<1%) and proved its ability to detect motions from contractile skeletal muscle tissue constructs. Finally, we showed that the sensor response can feed an autonomous control system, thus demonstrating the first proprioceptive bio-hybrid robot that can sense and respond to its contraction state. In addition to inspiring intelligent implantable systems, informative biomedical models, and other bioelectronic systems, the proposed technology will encourage strategies to exceed the durability, design, and portability limitations of biohybrid robots and confer them decisional autonomy, thus driving the paradigm shift between bio-actuators and intelligent bio-hybrid robots. One Sentence SummaryIntegrating soft mechanical sensors into engineered skeletal muscle tissue enables bio-hybrid robots with proprioception.

bioengineering↗

bioRxiv2023

Perfusable biohybrid designs for bioprinted skeletal muscle tissue

Engineered, centimeter-scale skeletal muscle tissue (SMT) can mimic muscle pathophysiology to study development, disease, regeneration, drug response, and motion. Macroscale SMT requires perfusable channels to guarantee cell survival and support elements to enable mechanical cell stimulation and uniaxial myofiber formation. Here, stable biohybrid designs of centimeter-scale SMT are realized via extrusion-based bioprinting of an optimized polymeric blend based on gelatin methacryloyl and sodium alginate, which can be accurately co-printed with other inks. A perfusable microchannel network is designed to functionally integrate with perfusable anchors for insertion into a maturation culture template. The results demonstrate that (i) co-printed synthetic structures display highly coherent interfaces with the living tissue; (ii) perfusable designs preserve cells from hypoxia all over the scaffold volume; and (iii) constructs can undergo passive mechanical tension during matrix remodeling. Extrusion-based multimaterial bioprinting with our inks and design realizes in vitro matured biohybrid SMT for biomedical, nutritional, and robotic applications.

bioengineering↗

bioRxiv2022

Chikungunya virus transmission in the Southernmost state of Brazil was characterized by self-limited cases (2017 to 2019) and a larger 2021 outbreak

Chikungunya is a reemerging arthropod-borne virus that has been causing large outbreaks in the Americas. In Brazil, Asian-Caribbean and ECSA genotypes have been detected and lead to large outbreaks in several states since 2014. In Rio Grande do Sul (RS), the southernmost State, the first autochthonous cases were reported in 2016. We employed genome sequencing and epidemiological investigation to characterize the increasing CHIKF burden in RS between 2017- 2021. Distinct lineages of the ECSA genotype were responsible for human infections between 2017-2021. Until 2020, CHIKV introductions were most travel associated and transmission was limited. Then, in 2021, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage. New CHIKV outbreaks are likely to occur in the near future due to abundant competent vectors and a susceptible population, exposing more than 11 million inhabitants to an increasing infection risk.

molecular biology↗

bioRxiv2019

Accelerated brain ageing and disability in multiple sclerosis

BackgroundBrain atrophy occurs in both normal ageing and in multiple sclerosis (MS), but it occurs at a faster rate in MS, where it is the major driver of disability progression. Here, we employed a neuroimaging biomarker of structural brain ageing to explore how MS influences the brain ageing process.\n\nMethodsIn a longitudinal, multi-centre sample of 3,565 MRI scans in 1,204 MS/clinically isolated syndrome (CIS) patients and 150 healthy controls (HCs) (mean follow-up time: patients 3*41 years, HCs 1*97 years) we measured brain-predicted age using T1-weighted MRI. Brain-predicted age difference (brain-PAD) was calculated as the difference between the brain-predicted age and chronological age. Positive brain-PAD indicates a brain appears older than its chronological age. We compared brain-PAD between MS/CIS patients and HCs, and between disease subtypes. In patients, the relationship between brain-PAD and Expanded Disability Status Scale (EDSS) at study entry and over time was explored.\n\nFindingsAdjusted for age, sex, intracranial volume, cohort and scanner effects MS/CIS patients had markedly older-appearing brains than HCs (mean brain-PAD 11*8 years [95% CI 9*1--14*5] versus -0*01 [-3*0--3*0], p<0*0001). All MS subtypes had greater brain-PAD scores than HCs, with the oldest-appearing brains in secondary-progressive MS (mean brain-PAD 18*0 years [15*4--20*5], p<0*05). At baseline, higher brain-PAD was associated with a higher EDSS, longer time since diagnosis and a younger age at diagnosis. Brain-PAD at study entry significantly predicted time-to-EDSS progression (hazard ratio 1*02 [1*01--1*03], p<0*0001): for every 5 years of additional brain-PAD, the risk of progression increased by 14*2%.\n\nInterpretationMS increases brain ageing across all MS subtypes. An older-appearing brain at baseline was associated with more rapid disability progression, suggesting brain-age could be an individualised prognostic biomarker from a single, cross-sectional assessment.\n\nFundingUK MS Society; National Institute for Health Research University College London Hospitals Biomedical Research Centre.

neuroscience↗

bioRxiv2019

10Kin1day: A bottom-up neuroimaging initiative

We organized 10Kin1day, a pop-up scientific event with the goal to bring together neuroimaging groups from around the world to jointly analyze 10,000+ existing MRI connectivity datasets during a 3-day workshop. In this report, we describe the motivation and principles of 10Kin1day, together with a public release of 8,000+ MRI connectome maps of the human brain.

neuroscience↗

bioRxiv2017

Progression of regional grey matter atrophy in multiple sclerosis

Grey matter atrophy is present from the earliest clinical stages of multiple sclerosis (MS), but the temporal ordering is poorly understood. We aimed to determine the sequence in which grey matter regions become atrophic in MS, and its association with disability accumulation.\n\nIn this longitudinal study, we included 1,417 subjects: 253 with clinically-isolated syndrome (CIS), 708 relapsing-remitting MS (RRMS), 128 secondary-progressive MS (SPMS), 125 primary-progressive MS (PPMS), and 203 healthy controls from 7 European centres. Subjects underwent repeated MRI scanning (total number of scans 3,604); the mean follow-up for patients was 2.41yrs (SD{+/-}1.97). Disability was scored using the Expanded Disability Status Scale (EDSS). We calculated the volume of brain grey matter regions and brainstem using an unbiased within-subject template. We used an established data-driven event-based model (EBM) to determine the sequence of occurrence of atrophy and its uncertainty. We assigned each subject to a specific EBM stage, based on the number of their atrophic regions. We used nested linear mixed-effects regression models to explore the associations between the rate of increase in the EBM stages over time, disease duration and annual rate of EDSS gain.\n\nThe first regions to become atrophic in CIS and relapse-onset MS patients (RRMS and SPMS) were the posterior cingulate cortex and precuneus, followed by the middle cingulate cortex, brainstem and thalamus. The sequence of atrophy in PPMS showed a similar involvement of the thalamus, cuneus, precuneus, and pallidum, followed by the brainstem and posterior cingulate cortex. The cerebellum, caudate and putamen showed early atrophy in relapse-onset MS and late atrophy in PPMS. Patients with SPMS showed the highest EBM stages (highest number of atrophic regions, all p<0.001) at study entry. Rates of increase in EBM stages were significantly different from healthy controls in all MS phenotypes, except for CIS. The increase in the number of atrophic regions (EBM stage) was associated with disease duration in all patients. EBM stage was associated with disability accumulation in RRMS independent of disease duration (p<0.0001).\n\nThis data-driven staging of atrophy progression in a large MS sample demonstrates that grey matter atrophy spreads to involve more regions over time. The sequence in which regions become atrophic is reasonably consistent across MS phenotypes. The spread of atrophy was associated with disease duration, and disability accumulation in RRMS.\n\nAbbreviations

neuroscience↗

bioRxiv2017

Deep grey matter volume loss drives disability worsening in multiple sclerosis

ObjectiveGrey matter (GM) atrophy occurs in all multiple sclerosis (MS) phenotypes. We investigated whether there is a spatiotemporal pattern of GM atrophy that is associated with faster disability accumulation in MS.\n\nMethodsWe analysed 3,604 brain high-resolution T1-weighted MRI scans from 1,417 participants: 1,214 MS patients (253 clinically-isolated syndrome[CIS], 708 relapsingremitting[RRMS], 128 secondary-progressive[SPMS], 125 primary-progressive[PPMS]), over an average follow-up of 2.41 years (standard deviation[SD]=1.97), and 203 healthy controls (HCs) [average follow-up=1.83 year, SD=1.77], attending 7 European centres. Disability was assessed with the Expanded-Disability Status Scale (EDSS). We obtained volumes of the deep GM (DGM), temporal, frontal, parietal, occipital and cerebellar GM, brainstem and cerebral white matter. Hierarchical mixed-models assessed annual percentage rate of regional tissue loss and identified regional volumes associated with time-to-EDSS progression.\n\nResultsSPMS showed the lowest baseline volumes of cortical GM and DGM. Of all baseline regional volumes, only that of the DGM predicted time-to-EDSS progression (hazard ratio=0.73, 95% CIs 0.65, 0.82; p<0.001): for every standard deviation decrease in baseline DGM volume, the risk of presenting a shorter time to EDSS worsening during follow-up increased by 27%. Of all longitudinal measures, DGM showed the fastest annual rate of atrophy, which was faster in SPMS (-1.45%), PPMS (-1.66%), and RRMS (-1.34%) than CIS (-0.88%) and HCs (-0.94%)[p<0.01]. The rate of temporal GM atrophy in SPMS (-1.21%) was significantly faster than RRMS (-0.76%), CIS (-0.75%), and HCs (-0.51%). Similarly, the rate of parietal GM atrophy in SPMS (-1.24-%) was faster than CIS (-0.63%) and HCs (-0.23%) (all p values <0.05). Only the atrophy rate in DGM in patients was significantly associated with disability accumulation (beta=0.04, p<0.001).\n\nInterpretationThis large multi-centre and longitudinal study shows that DGM volume loss drives disability accumulation in MS, and that temporal cortical GM shows accelerated atrophy in SPMS than RRMS. The difference in regional GM atrophy development between phenotypes needs to be taken into account when evaluating treatment effect of therapeutic interventions.

neuroscience↗