Tournier, P. | bioRxiv Science

bioRxiv2025

Geometrical Designs in Volumetric Bioprinting to Study Cellular Behaviors in Engineered Constructs

This study investigates the influence of geometrical variations in volumetrically printed (Vol3DP) structures on the attachment, survival, and organization of cancer cells (143b) and human umbilical vein endothelial cells (HUVECs). We adapted a gelatin methacryloyl (GelMA)-poly(ethylene glycol) diacrylate (Gel-PEG) resin for volumetric bioprinting. Compared to GelMA, Gel-PEG improved printing fidelity and resolution, superior mechanical properties, and reduced swelling. We fabricated disc-like constructs and channel geometries, including straight channels and angular designs of 60{degrees}, 90{degrees}, and 110{degrees} and cultured human umbilical vein endothelial cells (HUVECs) and 143b human osteosarcoma cells, a highly metastatic cell line, for up to 14 days. Using label-free holographic microscopy, we visualized cellular protrusions, important for adhesion and mechanosensing, in real-time and without staining, an advantage for long-term, live-cell analysis in 3D constructs. HUVECs adhered well, expressed CD31, and showed preferential spreading in channels with specific geometrical angles, indicating geometry-sensitive behavior. This is physiologically relevant, as it reflects the native mechanosensitive and alignment behavior of endothelial cells during vascular formation. In contrast, osteosarcoma cells spread uniformly throughout the constructs, formed dense, geometry-independent agglomerates, and exhibited enhanced growth and spreading within the Gel-PEG matrix compared to GelMA. This behavior is consistent with the aggressive and geometry-insensitive nature of metastatic tumor cells. These findings highlight Gel-PEGs utility for generating stable, biomimetic 3D environments and demonstrate the application of holographic microscopy for assessing cell- material interactions within volumetrically bioprinted constructs, underscoring the potential of this approach for developing vascularized models and studying mechanobiological responses in engineered tissues. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=193 SRC="FIGDIR/small/664683v1_ufig1.gif" ALT="Figure 1"> View larger version (64K): org.highwire.dtl.DTLVardef@9e3820org.highwire.dtl.DTLVardef@176eb5aorg.highwire.dtl.DTLVardef@558764org.highwire.dtl.DTLVardef@12bc5cb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Rejuvenating aged osteoprogenitors for bone repair

Aging is marked by a decline in tissue regeneration, posing significant challenges to an increasingly older population. Here, we investigate age-related impairments in calvarial bone healing and introduce a novel two-part rejuvenation strategy to restore youthful repair. We demonstrate that aging negatively impacts the calvarial bone structure and its osteogenic tissues, diminishing osteoprogenitor number and function and severely impairing bone formation. Notably, increasing osteogenic cell numbers locally fails to rescue repair in aged mice, identifying the presence of intrinsic cellular deficits. Our strategy combines Wnt-mediated osteoprogenitor expansion with intermittent fasting, which leads to a striking restoration of youthful levels of bone healing. We find that intermittent fasting improves osteoprogenitor function, benefits that can be recapitulated by modulating NAD+ dependent pathways or the gut microbiota, underscoring the multifaceted nature of this intervention. Mechanistically, we identify mitochondrial dysfunction as a key component in age-related decline in osteoprogenitor function and show that both cyclical nutrient deprivation and Nicotinamide mononucleotide rejuvenate mitochondrial health, enhancing osteogenesis. These findings offer a promising therapeutic avenue for restoring youthful bone repair in aged individuals, with potential implications for rejuvenating other tissues.

cell biology↗