Fivos Panetsos

Perfused brain-on-chip platforms preserve tissue viability, structure and electrophysiological activity. No validated long-term adult or human brain OoCs exist, highlighting a need for advanced functional readouts and translational applications.

The European Pathfinder THOR project envisages the creation of a vascularized fragment of tissue that can be implanted in a patient using regenerated silk fibers as its building blocks. The selection of regenerated silk as the main building block of the scaffold relies heavily on its outstanding biocompatibility in comparison with either other artificial polymeric fibers or even natural silk fibers. Additionally, regenerated fibers produced through the Dynamic Dope Destabilization Spinning (D3S^TM) process are shown to exhibit high mechanical performance as reflected in values of strain at breaking and work to fracture comparable to those of the natural material. It is further shown that these fibers are endowed with the unique property of self-adhesion whereby hydrated fibers attach to one another and may sustain detachment forces of up to a few tens of MPa, a property that facilitates the generation of the scaffold with the fibers as its basic building block. Lastly, regenerated silk fibers are shown to be efficiently decorated with either peptides or small proteins, such as the vascular endothelial growth factor (VEGF), or with antibodies. The performance of both non-functionalized and decorated silk fibers is assessed in two different in vitro biological systems: (1) endothelial cell cultures, and (2) organotypic brain slice cultures. Together, these results support the use of regenerated silk fibers as versatile building blocks for biofunctional tissue scaffolds and provide experimental validation of the tissue engineering strategy established by the THOR project.

Cardiovascular diseases (CVDs) remain a leading source of morbidity and mortality worldwide. Although heart transplantation is an established treatment for selected patients with end-stage heart failure, the difficulty in obtaining enough donors and the problems associated with compatibility force the search for new strategies to mitigate these effects. Cardiac patches, a combination of therapeutic elements, such as cells and drugs deposited on a biomimetic scaffold, are particularly promising for repairing the long-term cardiac damage from a perspective based on tissue engineering. However, building these patches entails the compliance with extensive and exhaustive conditions and regulations. Key issues identified in the building process of cardiac patches are the cell–scaffold interaction, including the intensity and duration of this interaction. The present study is intended to develop a robust procedure that allows quantifying the adhesion between decellularized matrices and cells through single-cell force spectroscopy (SCFS) measurements. Determining this adhesion force is essential to ensure cell retention and therapeutic action in the damaged area and, therefore, to be able to design an advanced therapy medicinal product. The whole procedure is validated by measuring the adhesion of allogeneic adipose-derived mesenchymal stromal cells to a decellularized porcine myocardium patch.

Direct cellular reprogramming, the conversion of one somatic cell type into another, represents a remarkable advancement in regenerative medicine. Its potential to transform fibrotic tissue into functional parenchyma underscores its therapeutic promise. However, several critical challenges remain unresolved, including limited reprogramming efficiency, the long-term functional stability of converted cells, their integration within pre-existing cellular circuits, and safety concerns related to transgene integration and immunological responses to reprogramming-based viral vectors. Approaches based on the exogenous administration of recombinant proteins and miRNAs have also emerged, though these rely on factors that are naturally prone to exhaustion and degradation, potentially restricting their efficacy. This review is divided into three main sections. The first part addresses direct cellular reprogramming in the context of other cell-based applications, outlining its main applications and current biological limitations. The second part examines how different biomaterials, ranging from hydrogel scaffolds to nanoparticles, can modulate direct cellular reprogramming by providing mechanical and topographical cues and by enabling tighter control over the concentration and spatiotemporal dynamics of reprogramming factors and viral vectors. The third part discusses key findings in biomaterial-assisted reprogramming strategies, highlighting emerging opportunities for clinically translatable approaches. The convergence of regenerative biology and biomaterials science may ultimately generate advanced gel-based and hybrid cellular reprogramming platforms for in vitro testing and, in situ applications, for promoting cell fate stabilization and facilitating the regeneration of damaged tissues and organs.

Chemotactic microorganisms operate in environments where signals are not only noisy but temporally structured, with finite correlation times that can severely impair gradient sensing and target localization. While previous models have extensively characterized the effects of fluctuating environments on individual chemotaxis, most theoretical frameworks treat agents as non-interacting, leaving unresolved how inter-bacterial interactions reshape collective robustness under temporally correlated noise. Here, we introduce a two-dimensional agent-based model of interacting run-and-tumble bacteria navigating noisy chemotactic landscapes. We show that short-range isotropic cohesion induces a two-stage collective response: interactions first stabilize population connectivity and above a finite interaction threshold, this structural cohesion translates into robust target localization even in regimes where individual chemotaxis fails. The resulting transition reveals an intermediate phase of cohesive but weakly localized states, demonstrating that structural condensation and functional targeting are distinct collective observables. We further demonstrate that selective heterotypic interactions in binary populations produce a structurally distinct collective regime characterized by dynamically maintained red–blue contact networks composed of transient mixed dimers and local heterotypic motifs. Unlike isotropic cohesion, selective interactions reorganize local contact topology without generating macroscopic condensation. These structures are quantitatively characterized through bond density, mixing statistics, and anisotropy metrics, and are governed primarily by interaction specificity rather than by environmental noise persistence. Together, these results establish that collective chemotactic behavior is controlled by the interplay between temporal signal correlations and interaction topology. More broadly, in this work we identify collective localization and internal organization as partially independent emergent properties of interacting active matter under fluctuating environments.

The ability of chemotactic populations to localize and track targets in fluctuating environments depends critically on the temporal structure of environmental signals. Using a minimal agent-based framework of non-interacting run-and-tumble cells implementing an E. coli-inspired temporal sensing strategy, populations are exposed to static and moving chemoattractant fields perturbed by noise with controlled temporal structure, spanning white, pink (1/f), and correlated Ornstein-Uhlenbeck processes. Chemotactic populations are found to act as temporal filters, robustly suppressing fast fluctuations while remaining highly sensitive to slowly varying perturbations. As a consequence, chemotactic performance is governed not by noise amplitude, but by its temporal correlations. By continuously varying the noise correlation time, a critical regime emerges at τ _c ~ τ _run , where aggregates lose stability, tracking errors increase sharply, and spatial dispersion rises. Power spectral analysis further shows that the low-frequency power fraction of the signal provides a strong predictor of failure, outperforming total signal variance and establishing a direct link between environmental noise spectra and collective behavior. Introducing external flow reveals that advective transport amplifies noise-induced destabilization when it overlaps the chemotactic capture region, defining a combined spatiotemporal constraint on robustness. Together, these results identify temporal correlations and spectral structure as fundamental control parameters for chemotactic organization and provide a quantitative framework for predicting and designing collective behavior in fluctuating environments.

There is broad consensus that successful repair of severe peripheral nerve injuries requires recreating key structural and cellular features of the natural regenerative process, particularly the action of Bands of Büngner (BoB), longitudinal Schwann cell (SC) structures that guide regenerating axons. Current biomaterial‐based strategies have shown limited efficacy, in part because they do not sufficiently reproduce the anisotropic and cellular microenvironment established by BoB, resulting in disorganized axonal growth and reduced regenerative efficiency across long gaps. To address this limitation, a biohybrid scaffold designed to promote Schwann cell self‐organization into Büngner‐like structures through defined physical cues. Rather than relying solely on biochemical supplementation is developed, this system leverages anisotropic fiber architecture to induce SC alignment and early activation‐associated phenotypic modulation. In this study, a self‐organizing biohybrid BoB (BBoB) construct formed by Schwann cells within an aligned fiber‐based scaffold is presented. It is demonstrated that these engineered structures recapitulate key morphological features of native BoB in vitro and promote enhanced axonal regeneration across a 11 mm sciatic nerve defect in vivo. Together, these findings support the concept that physically programmed Schwann cell organization within biomaterial conduits can enhance peripheral nerve regeneration, using clinically accessible biomaterials and autologous Schwann cells.

The efficient design of biohybrid materials requires controlling the interaction between the cell and the material for a wide range of possible combinations. Single cell force spectroscopy (SCFS), an atomic force microscopy (AFM) experimental procedure based on the binding of an individual cell to an AFM cantilever and the assessment of the adhesion force between the cell and a target substrate, represents one of the most promising alternatives to characterize the interaction between cell and material. However, SCFS relies on the efficient binding of the cell to the AFM in order to avoid drawbacks, such as the detachment of the cell. In this work, three different versatile and robust procedures are presented that allow for the binding of either non-adherent (CD4⁺ T-lymphocytes) or adherent (mesenchymal stem cells, MSC) cells to the AFM probe. The three crosslinking strategies comprise (1) the streptavidin/biotin system, (2) sulfhydryl group-based crosslinkers, and (3) “click” (bioorthogonal) chemistry. Additionally, three decoration schemes of the functionalized AFM probes are explored: a specific antibody, concanavalin A, and direct binding of the cell through azide-derivatized membrane proteins. Differences are observed between these alternatives and it is found that the strength of the interaction (in decreasing order) is as follows: specific antibody, concanavalin A, and binding through azide-derivatized proteins.

Background/Objectives: Inflammatory processes, both acute and chronic, encompass a wide range of autoimmune, metabolic, and neurodegenerative conditions. Conventional treatments, primarily anti-inflammatories and immunosuppressants, provide partial relief but are often hampered by adverse effects and limited durability. Mesenchymal stem cells (MSCs) have emerged as a powerful new treatment due to their immunomodulatory and anti-inflammatory properties, primarily mediated through their secretome, which is a complex mixture of bioactive factors. Secretome-based therapeutic strategies show strong potential for controlling inflammation, mitigating oxidative stress, and supporting tissue regeneration and repair. However, the therapeutic efficacy of MSCs’ secretome is subject to modification by concurrent anti-inflammatory drug regimens used in clinical settings. Methods: To evaluate the effect of combinatorial treatment strategies on the secretome of the MSCs, we employed an in vitro retinal inflammation model to investigate whether the exposure of the MSCs to five representative anti-inflammatory drugs (ketorolac, diclofenac, α-lipoic acid, N-acetyl-L-cysteine, and nicotinamide) impacts the functionality of the resulting secretome. Specifically, we evaluated the effect of the above-mentioned drugs on the anti-inflammatory properties of the secretome in relation to the secreted levels of two main MSC secretome factors—the Brain-Derived Neurotrophic Factor (BDNF) and the Vascular Endothelial Growth Factor (VEGF)—and on the secretome’s pro-metabolic activity. Results: Our findings provide evidence that the presence of any of the tested drugs during MSC secretome production does not compromise its anti-inflammatory activity; BDNF and VEGF levels remain stable, and the secretome retains a high degree of its pro-metabolic effect. Conclusions: These results underscore the robustness and clinical resilience of MSC-based therapies, even when administered alongside pharmacological agents. This work advances the translational viability of MSC therapies for inflammatory diseases and supports the development of safe, combinatorial treatment strategies.