Biology subjects

Bernero, M.

Publications and source records attributed to Bernero, M..

4 recordsLinked to original sources

bioRxiv2025

Volumetric Bioprinting of Bone-like Mineralizing Hydrogel Constructs in the Presence of High Cell Densities and Mineral Precursors

A major challenge in bone tissue engineering is the embedding of osteocyte-like cells at high density within a mineralized matrix at the micro-scale and a trabecular-like architecture at the macro-scale. Volumetric bioprinting (VBP) enables rapid creation of complex cell-laden constructs through tomographic light projections. However, integrating both high cell densities and inorganic mineral precursors into VBP processes poses challenges due to light scattering, which can compromise print fidelity. In this study, we aim to combine bioinspired polymer-induced liquid-phase precursor (PILP) mineralization with VBP to fabricate cell-laden gelatin methacryloyl hydrogel constructs with amorphous mineral precursors. By stabilizing amorphous mineral precursors with poly-aspartic acid, light scattering is sufficiently reduced to enable printing. Tuning the refractive index of this mineralizing bioresin allows fast VBP of mineralized bone-like constructs with cell densities of up to 3 million cells ml-1. The constructs display high cell viability (>90%) and enhanced mineralization when cultured in osteogenic conditions with {beta}-glycerophosphate. Encapsulated human mesenchymal stromal cells exhibit an early osteocytic phenotype after 28 days of differentiation. Collectively, this PILP-assisted VBP platform holds promise for the development of advanced in vitro bone models with more physiologically relevant architecture and cellular composition.

bioengineering↗

bioRxiv2023

Dual carbon sequestration with photosynthetic living materials

Natural ecosystems offer efficient pathways for carbon sequestration, serving as a resilient approach to remove CO2 from the atmosphere with minimal environmental impact. However, the control of living systems outside of their native environments is often challenging. Here, we engineered a photosynthetic living material for dual CO2 sequestration by immobilizing photosynthetic microorganisms within a printable polymeric network. The carbon concentrating mechanism of the cyanobacteria enabled accumulation of CO2 within the cell, resulting in biomass production. Additionally, the metabolic production of OH- ions in the surrounding medium created an environment for the formation of insoluble carbonates via microbially-induced calcium carbonate precipitation (MICP). Digital design and fabrication of the living material ensured sufficient access to light and nutrient transport of the encapsulated cyanobacteria, which were essential for long-term viability (more than one year) as well as efficient photosynthesis and carbon sequestration. The photosynthetic living materials sequestered approximately 2.5 mg of CO2 per gram of hydrogel material over 30 days via dual carbon sequestration, with 2.2 {+/-} 0.9 mg stored as insoluble carbonates. Over an extended incubation period of 400 days, the living materials sequestered 26 {+/-} 7 mg of CO2 per gram of hydrogel material in the form of stable minerals. These findings highlight the potential of photosynthetic living materials for scalable carbon sequestration, carbon-neutral infrastructure, and green building materials. The simplicity of maintenance, coupled with its scalability nature, suggests broad applications of photosynthetic living materials as a complementary strategy to mitigate CO2 emissions.

bioengineering↗

bioRxiv2022

A Synthetic Stress-relaxing Photoresin for Ultrafast Volumetric Bioprinting

Tomographic volumetric bioprinting (VBP) enables fast photofabrication of cell-laden hydrogel constructs in one step, addressing the limitations of conventional layer-by-layer additive manufacturing. However, existing biomaterials that fulfill the physicochemical requirements of VBP are limited to gelatin-based photoresins of high polymer concentrations. The printed microenvironments are predominantly static and stiff, lacking sufficient capacity to support 3D cell growth. We here report a dynamic resin based on thiol-ene photo-clickable polyvinyl alcohol (PVA) and thermo-sensitive sacrificial gelatin for fast VBP of functional ultrasoft cell-laden hydrogel constructs within 7-15 seconds. Using gelatin allows VBP of permissive hydrogels with low PVA contents of 1.5%, providing a stress-relaxing environment for fast cell spreading, 3D osteogenic differentiation of embedded human mesenchymal stem cells and matrix mineralization. Additionally, site-specific immobilization of molecules-of-interest inside a PVA hydrogel is achieved by 4D tomographic thiol-ene photopatterning. This technique may enable spatiotemporal control of cell-material interactions and guided in vitro tissue formation using programmed cell-friendly light. Altogether, this study introduces a synthetic dynamic photoresin enabling fast VBP of functional ultrasoft hydrogel constructs with well-defined physicochemical properties and high efficiency.

bioengineering↗

bioRxiv2021

Nanoconfinement of Microvilli Alters Gene Expression and Boosts T cell Activation

T cells sense and respond to their local environment at the nanoscale by forming small actin-rich protrusions, called microvilli, which play critical roles in signaling and antigen recognition, particularly at the interface with the antigen presenting cells. However, the mechanisms by which microvilli contribute to cell signaling and activation is largely unknown. Here, we present a tunable engineered system that promotes microvilli formation and T cell signaling via physical stimuli. We discovered that nanoporous surfaces favored microvilli formation, and markedly altered gene expression in T cells and promoted their activation. Mechanistically, confinement of microvilli inside of nanopores leads to size-dependent sorting of membrane-anchored proteins, specifically segregating CD45 phosphatases and T cell receptors (TCR) from the tip of the protrusions when microvilli are confined in 200 nm pores, but not in 400 nm pores. Consequently, formation of TCR nanoclustered hotspots within 200 nm pores, allows sustained and augmented signaling that prompts T cell activation even in the absence of TCR agonists. The synergistic combination of mechanical and biochemical signals on porous surfaces presents a straightforward strategy to investigate the role of microvilli in T cell signaling as well as to boost T cell activation and expansion for application in the growing field of adoptive immunotherapy.

bioengineering↗