Biology subjects

Boccaccini, A. R.

Publications and source records attributed to Boccaccini, A. R..

7 recordsLinked to original sources

bioRxiv2026

Mechanochemical synchronization of force oscillations in connective tissue models

Cells in a tissue coordinate their behavior collectively by mechanical and chemical feedback with their surroundings. To study how such feedback mechanisms interact, we embed multicellular spheroids from mouse and primary human fibroblasts of different origin in 3D collagen matrices. Immediately after embedding, spheroids apply steadily increasing, radially symmetric, inward-directed forces to the surrounding matrix. Typically, within a few hours, collective force oscillations emerge with an average time interval of {approx}30 min. Similar force oscillations also arise in engineered, parallel-aligned microtissues attached to flexible pillars. Force oscillations propagate between neighboring cells as a mechanical wave, accompanied by calcium waves that travel at comparable speeds of several hundred m/min. Blocking gap junctions or mechanosensitive Piezo1 channels impairs these oscillations, indicating that calcium signaling contributes to their propagation. Their amplitude and frequency are regulated by integrin-mediated feedback in actin-rich protrusions and by ERK signaling, which also controls collective invasion into the surrounding matrix. Neighboring spheroids mechanically synchronize their force oscillations in phase and frequency over distances of up to {approx}2 mm without direct contact. Together, our results show that oscillatory mechanochemical feedback enables multicellular systems to coordinate force generation and invasive migration across cellular and millimeter length scales in 3D matrices.

biophysics↗

bioRxiv2026

Mechanotranscriptomic Profiling of Breast Cancer Cells Intravasated from Engineered Microtumors

Intravasation is the process by which cancer cells breach the physical boundaries of a primary tumor and enter blood or lymphatic vessels. In this work, MCF-7 breast cancer cells were cultured within polymer-based microcapsules (here referred to as artificial microtumors) to investigate the transcriptomic and morpho-mechanical changes occurring in cancer cells during their release from these matrices, mimicking in vitro the process of intravasation. Our results show that even confined and released cancer cells share approximately 95% of their global transcriptomic profiles, intravasation-like cells exhibited marked differences in the expression of pathogenic hallmarks, including pathways associated with cell proliferation, immunosurveillance, and dormancy. Notably, a clear upregulation of YAP/TAZ signaling was observed in released cells, a result further supported by single-cell traction force microscopy assays, demonstrating that those cells exhibit higher biomechanical activity compared to cells located within artificial microtumors or those cultured on conventional 2D flasks, as shown for intravasated cells in vivo. To further enrich our investigation, the mechanotranscriptomic activity of MCF-7 cells was compared with suspended spheroids cultured on non-adherent surfaces (i.e., agarose hydrogels). Our results show that released cells displayed increased biomechanical activity and elevated expression of malignant markers, indicating that mechanical stress, beyond cell-cell contact alone, is required to trigger malignant responses. These observations were further supported by co-culture studies of MCF-7 cells with human fibroblasts and endothelial cells, which showed reduced proliferative and invasive capacities under confinement. Overall, our findings demonstrate that shifts in mechanical and metabolic stress, as experienced during intravasation, act as critical stimuli driving mechanotranscriptomic programs associated with cancer progression.

cancer biology↗

bioRxiv2025

Fine-tuning cell-mimicking polyacrylamide microgels: Sensitivity to microscale reaction conditions in droplet microfluidics

The ability to shape polyacrylamide (PAAm) hydrogels using droplet microfluidics enables the production of microgel particles that mimic the cellular physical properties, opening new avenues in mechanobiology. Precisely controlling microgel size and elasticity is crucial yet complex, as various factors influence polymerization and the resulting network structure. While it is well established that chemical reactions in microdroplets are typically faster and more homogeneous than in bulk systems, an often-overlooked aspect is the increased sensitivity of these microreactors: minor variations in chemical or physical parameters can lead to significant changes in the resulting microgel properties. Our study identifies flow conditions as a key factor influencing both microgel elasticity and size, by modulating interfacial transport during gelation. Using a flow-focusing microfluidic chip, we generated pre-gel droplets with identical composition dispersed in an oil phase, systematically varying the PAAm-to-oil flow rate ratio while keeping the total flow rate constant. This approach yields droplets with minimal diameter variation (<1 {micro}m), yet produces beads with distinct Youngs moduli, despite identical total monomer concentrations. Further analysis revealed that the catalyst transport across the oil-water interface significantly affects the polymerization efficiency and polymer network. Our findings highlight that despite the advantages of droplet-based polymerization, achieving reproducible microgel properties requires careful control of flow parameters. This underscores the importance of precise microfluidic control in advancing PAAm microgel applications in biophysics.

biophysics↗

bioRxiv2025

Mechanical impact on neural stem cell lineage decisions in human brain organoids

During neurodevelopment neural stem cells give rise to a spatially patterned tissue in which a regionally differentially regulated balance between proliferation and differentiation produces the fine-tuned number of neurons and macroglia necessary for a functional central nervous system. The cells driving these highly intricated developmental processes of patterning, growth and differentiation are constantly exposed to a mechanical environment that is however variable between different brain regions and along differentiation trajectories. Here we demonstrate that both, acute mechanical manipulations as well as a persistent change in the mechanical environment provided to human brain organoids, instruct neural stem cell lineage decisions. Furthermore, we dissect the underlying changes in the molecular program of organoid-resident cells by bulk- and single cell RNA-sequencing and reveal that mechanical manipulations impact on molecular programs governing early patterning events as well as cell-type specifically alter cellular metabolism. Thus, our results unravel a regulatory network linking mechanics and neural stem cell lineage decisions.

neuroscience↗

bioRxiv2022

When Mechanical Stress Matters: Generation of Polyploid Giant Cancer Cells in Tumor-like Microcapsules

In this work, we studied the generation and rising of polyploid cancer cells as a product of mechanical stress. To this purpose, MCF7 breast cancer cells were cultured on 2D (i.e. flasks, or flat hydrogels), and in 3D milieus (i.e. Spheroids, or immobilized within alginate-gelatin microbeads, named in this work as tumor-like microcapsules), and further analyzed by biophysical and genetic methods (i.e. single-cell Traction Force Microscopy and RNA-seq respectively). Our results show that MCF7 cells preconditioned onto 2D surfaces exhibit a low number of polynucleated cells, while their culture in 3D environments triggered their progressive generation with time. Genetic studies enabled us to determine that polyploid cells found in tumor-like microcapsules are likely originated by cell-cell fusion and disrupted cytokinesis, showing most of the genetic markers for Polyploid Giant Cancer Cell, while cells cultured as spheroids seem to be likely generated by other mechanisms, such as cell cannibalisms, entosis, or emperipolesis. Our outcomes strongly suggest that both mechanical stress and confinement are required to stimulate cell polyploidy, which can be easily addressed by the immobilization of breast cancer cells in tumor-like microcapsules.

bioengineering↗

bioRxiv2021

Stress relaxation amplitude of hydrogels determines migration, proliferation, and morphology of cells in 3-D

The viscoelastic behavior of hydrogel matrices sensitively influences the cell behavior in 3D culture and biofabricated tissue model systems. Previous reports have demonstrated that cells tend to adhere, spread, migrate and proliferate better in hydrogels with pronounced stress relaxation. However, it is currently unknown if cells respond more sensitively to the amplitude of stress relaxation, or to the relaxation time constant. To test this, we compare the behavior of fibroblasts cultured for up to 10 days in alginate and oxidized alginate hydrogels with similar Youngs moduli but diverging stress relaxation behavior. We find that fibroblasts elongate, migrate and proliferate better in hydrogels that display a higher stress relaxation amplitude. By contrast, the cells response to the relaxation time constant was less pronounced and less consistent. Together, these data suggest that it is foremost the stress relaxation amplitude of the matrix that determines the ability of cells to locally penetrate and remodel the matrix, which subsequently leads to better spreading, faster migration, and higher cell proliferation. We conclude that the stress relaxation amplitude is a central design parameter for optimizing cell behavior in 3-D hydrogels.

biophysics↗

bioRxiv2020

In vivo validation of spray-dried mesoporous bioactive glass microspheres acting as prolonged local release systems for BMP-2 to induce bone regeneration

Despite years of diligent research in fracture healing, an unmet clinical need for safe and effective pharmacological treatments to improve bone regeneration persists with 10 - 20 % of fracture cases exhibiting impaired healing. Bone morphogenetic protein-2 (BMP-2) is a known key mediator of physiological bone regeneration and is clinically approved for selected musculoskeletal interventions. Yet, broad usage of this growth factor is impeded due to side effects that are majorly evoked by high dosages and burst release kinetics. In this study, mesoporous bioactive glass microspheres (MBGs) produced by an aerosol assisted spray-drying, scalable process were found to be biocompatible and to induce a pro-osteogenic response on human MSCs in vitro. Loading of the MBGs with BMP-2 resulted in prolonged, low-dose BMP-2 release without affecting the material features. In a pre-clinical rodent model, BMP-2 loaded MBGs significantly enhanced bone formation and influenced the microarchitecture of newly formed bone. The MBG carriers alone performed equal to the untreated (empty) control in most parameters tested, while additionally exerting mild pro-angiogenic effects. Using MBGs as a biocompatible, pro-regenerative carrier for local and sustained low dose BMP-2 release could limit side effects, thus enabling a safer usage of BMP-2 as a potent pro-osteogenic growth factor.

cell biology↗