Biology subjects

Gropplero, G.

Publications and source records attributed to Gropplero, G..

6 recordsLinked to original sources

bioRxiv2025

Shaping and probing living tissues with magnetic bioprinting

Mechanical and geometric cues play a crucial role in vivo, regulating both morphogenetic processes and proper tissue function. This is particularly evident in skeletal muscle, where aligned architecture is essential for myogenesis and functional force generation. However, precisely engineering tissue geometry at both macroscopic and microscopic scales while simultaneously controlling internal mechanical forces remains a significant challenge. In this study, we introduce a magnetic tissue engineering platform based on a magnetic bioprinting technique, enabling precise control of biophysical cues that guide in vitro tissue morphogenesis. Applied here to skeletal muscle, this approach allows for the rapid fabrication of cohesive tissues in any desired shape using cells labeled with magnetic nanoparticles. Additionally, multiple cell types can be incorporated and spatially organized within the same construct through magnetic segregation. Optimizing tissue geometry further enables magnetic actuation, including the ability to trap and maintain tissue shape over time. Furthermore, this magnetic platform facilitates the investigation of how tissue architecture influences mechanical properties, such as resistance to rupture. Overall, this study highlights the significant potential of magnetic bioprinting and stimulation for controlling tissue morphology and advancing biomechanical research.

bioengineering↗

bioRxiv2025

Magnetic printing and actuation of stretchable muscle tissue

While the link between tissue organization, stimulation, and function is now acknowledged as crucial for tissue development, engineering tissues with precise, long-lasting shapes and the capability for mechanical stimulation remains challenging. This study addresses this challenge by developing a next-generation magnetic bioprinting approach to create anisotropic, shape-controlled, scaffold-free, and stretchable skeletal muscle constructs. Murine skeletal muscle cells and human induced pluripotent stem cell-derived skeletal muscle cells, labeled with iron oxide nanoparticles, were magnetically bioprinted into wrench-shaped tissues. Their magnetic properties allowed these tissues to be clipped onto magnetic needles, preserving their shape over two weeks of culture while promoting anisotropic differentiation and myoblast fusion. Additionally, the magnetic tissues could be stretched by up to 100%, enhancing their anisotropy and improving muscle maturation. This magnetic toolbox demonstrates significant advancements in muscle tissue engineering, as evidenced by enhanced indicators of myoblast differentiation, including cell fusion, increased myogenic maturation and contractility. These findings highlight the potential of magnetic-based techniques for developing advanced muscle-on-chip systems and other complex tissue constructs.

bioengineering↗

bioRxiv2025

Harnessing hydrodynamics for high-yield production of extracellular vesicles from stem cells spheroids with specific cargo profiling

This study presents a novel method and device for the hydrodynamic production of extracellular vesicles (EVs) derived from biomimetic multicellular 3D spheroids, enabling high-throughput particle release that is 10 to 20 times higher than in non-stimulated conditions. The device facilitates the formation of spheroids from human mesenchymal stem cells (hMSCs), offering an all-in-one approach for both spheroid generation and EV release. Production times are reduced to just a few hours, with yield further increased by alternating periods of high hydrodynamic flow and spheroid recovery in a sequential production approach. Using this system, we explored the impact of hydrodynamic and starvation conditions on the protein cargo of EVs, identifying distinct protein markers through proteomics. Specifically, hydrodynamic stimulation enriched EVs in plasma membrane-derived and mitochondrial proteins, revealing divergent biogenesis pathways. Importantly, the produced EVs exhibited therapeutic properties, with demonstrated effects in wound healing, angiogenesis, and anti-inflammatory responses, some showing enhanced efficacy under hydrodynamic stimulation.

bioengineering↗

bioRxiv2024

PIEZO-dependent mechano-sensing of the niche is essential for intestinal stem cell fate decision and maintenance

Stem cells continuously perceive and respond to various environmental signals to maintain homeostasis. In addition to biochemical factors, the stem cell niche is subjected to mechanical and physical cues. However, it remains unclear how stem cells can sense mechanical signals from their niche in vivo. Since intestinal stem cells constantly and directly face the external environment, we investigated the roles of mechano-sensing PIEZO ion channels in the gut stem cell niche. By employing mouse genetics and performing single-cell RNAseq analysis, we revealed the absolute requirement for PIEZO channels in intestinal stem cell (ISC) state dynamics and maintenance. In vivo measurement of basement membrane region stiffness demonstrated that ISCs reside in a more rigid microenvironment at the bottom of the crypt. Using 3D and 2D organoid systems combined with bioengineered substrates and a cell stretching device, we found that PIEZO channels are activated by high extracellular matrix stiffness and tissue tension to modulate ISC behavior. This study delineates the mechanistic cascade of PIEZO channel activation in ISCs from the upstream extracellular stimuli through the downstream signaling activation that coordinates stem cell fate decision and maintenance.

cell biology↗

bioRxiv2024

Decoupling shear stress and pressure effects in the biomechanics of autosomal dominant polycystic kidney disease using a perfused kidney-on-chip.

Kidney tubular cells are submitted to two distinct mechanical forces generated by the urine flow: shear stress and hydrostatic pressure. In addition, the mechanical properties of the surrounding extracellular matrix modulate tubule deformation under constraints. These mechanical factors likely play a role in the pathophysiology of kidney diseases as exemplified by autosomal dominant polycystic kidney disease, in which pressure, flow and matrix stiffness have been proposed to modulate the cystic dilation of tubules with PKD1 mutations. The lack of in vitro systems recapitulating the mechanical environment of kidney tubules impedes our ability to dissect the role of these mechanical factors. Here we describe a perfused kidney-on-chip with tunable extracellular matrix mechanical properties and hydrodynamic constraints, that allows a decoupling of shear stress and flow. We used this system to dissect how these mechanical cues affect Pkd1-/- tubule dilation. Our results show two distinct mechanisms leading to tubular dilation. For PCT cells (proximal tubule), overproliferation mechanically leads to tubular dilation, regardless of the mechanical context. For mIMCD-3 cells (collecting duct), tube dilation is associated with a squamous cell morphology but not with overproliferation and is highly sensitive to extracellular matrix properties and hydrodynamic constraints. Surprisingly, flow alone suppressed Pkd1-/- mIMCD-3 tubule dilation observed in static conditions, while the addition of luminal pressure restored it. Our in vitro model emulating nephron geometrical and mechanical organization sheds light on the roles of mechanical constraints in ADPKD and demonstrates the importance of controlling intraluminal pressure in kidney tubule models.

biophysics↗

bioRxiv2023

Comparative transcriptomics reveal a novel tardigrade specific DNA binding protein induced in response to ionizing radiation

Tardigrades, microscopic animals found in virtually all ecosystems, are renowned for their remarkable ability to withstand extreme conditions. Recent studies have identified novel tardigrade specific protein families that aid in resistance to desiccation and ionizing radiation (IR). Notably, a tardigrade specific DNA binding protein called Dsup (for DNA damage suppressor) has been found to protect from X-ray damage in human cells and from hydroxyl radicals in vitro. However, Dsup has only been found in two species within the Hypsibioidea superfamily. To better understand mechanisms underlying radio-resistance in the Tardigrada phylum, we first characterized DNA damage and repair in response to IR in the model species Hypsibius exemplaris. By analysis of phosphorylated H2AX, we demonstrated the induction and repair of DNA double-strand breaks after IR exposure. Importantly, the rate of single-strand breaks induced was roughly equivalent to that in human cells, suggesting that DNA repair plays a predominant role in the remarkable radio-resistance of tardigrades. In order to identify novel tardigrade specific genes involved, we next conducted a comparative transcriptomics across three species, H. exemplaris, Acutuncus antarcticus and Paramacrobiotus fairbanksi, the latter belonging to the Macrobiotoidea superfamily known to lack Dsup homologs. In all three species, many genes of DNA repair were among the most strongly overexpressed genes alongside a novel tardigrade specific gene, named Tardigrade DNA damage Response protein 1 (TDR1). We found that TDR1 protein interacts with DNA and forms aggregates at high concentration suggesting it may condensate DNA and act by preserving chromosome organization until DNA repair is accomplished. Remarkably, when expressed in human cells, TDR1 improved resistance to Bleomycin, a radiomimetic drug. Based on these findings, we propose that TDR1 is a novel tardigrade specific gene responsible for conferring resistance to IR. Our study sheds light on mechanisms of DNA repair helping to cope with high levels of DNA damage. Furthermore, it suggests that at least two tardigrade specific genes, respectively for Dsup and TDR1, have independently evolved DNA-binding functions that contribute to radio-resistance in the Tardigrada phylum.

molecular biology↗