Biology subjects

Fuentes, J.

Publications and source records attributed to Fuentes, J..

5 recordsLinked to original sources

bioRxiv2026

3D-bioprinted skeletal muscle with tailored myofibre architecture

Engineered skeletal muscle tissue (eSMT) contractile function strongly depends on the alignment and orientation of its myofibres, as force generation and transmission are intrinsically linked to its microstructural architecture. However, fabricating truly functional eSMT with controlled myofibre architecture remains a major challenge. Here, we present a method that combines extrusion-based 3D bioprinting with custom multi-pillar anchoring systems to guide myofibre orientation. Using this approach, we successfully fabricated functional eSMTs with parallel, fusiform, bipennate, and circular architectures. We then integrated these basic designs into a functional system comprising multiple 3D-bioprinted eSMTs replicating the morphology and myofibre architecture of facial musculature. By recapitulating native muscle architecture, this approach advances the engineering of functional eSMT for multiple biomedical applications and establishes a foundation for next-generation biohybrid robotics.

bioengineering↗

bioRxiv2025

Carbohydrates and the oxidative branch of the pentose phosphate pathway modify Bacteroides thetaiotaomicron phage resistance by phase variable S-layers

The human gut microbiota consists of hundreds of bacterial species, some of which persist in the presence of lytic phage that infect them. Bacteroides employ numerous phase-variable strategies to survive in the presence of phage, including capsular polysaccharides (CPS) and S-layer lipoproteins. We previously reported that a Bacteroides thetaiotaomicron strain lacking CPS exhibits almost complete resistance to multiple phages when forced to express the S-layer protein BT1927. However, this strain was only resistant after certain growth conditions, suggesting nutritional variables alter infection and resistance. We grew this strain on various simple sugars and polysaccharides finding that some substrates (fructose, glucose) promote strong resistance to a single phage (ARB25) while others like N-acetylgalactosamine (GalNAC) and mucin O-glycans increase susceptibility. Mixing fructose and GalNAc indicates the effects of GalNAc are dominant. Despite increasing ARB25 susceptibility, GalNAc did not reduce BT1927 transcript or protein levels. Instead, GalNAc reduced the amount of BT1927 displayed on the cell surface and increased outer membrane vesiculation. Mutants in any of the 3 steps of the oxidative branch of the pentose phosphate pathway--grown in fructose--behaved similarly to wild-type cells grown in GalNAc, illuminating this pathway in regulation of sugar-mediated phage-resistance. Despite promoting strong resistance, cells grown in glucose/fructose sometimes displayed sub-populations that appeared to completely lack surface BT1927, suggesting another checkpoint exists to control whether this phage defense is deployed. Finally, we show the mucin sugar GalNAc increases susceptibility to several other phage, which has implications for B. thetaiotaiomicron persistence in niches like the mucus layer. ImportanceThe persistence of viruses that infect bacteria (bacteriophages or phages) in the human gut microbiome and their effects on bacterial physiology and host health are active areas of investigation. Our study investigates how various sugars and polysaccharides alter phage susceptibility and resistance in the model gut symbiont Bacteroides thetaiotaomicron to lytic phages that are capable of infecting it. Our finding that the mucin sugar, N-acetylgalactosamine, and mucin O-glycans that contain this sugar reduce B. thetaiotaomicron resistance to multiple phages has implications for how this symbiont persists in different gut microhabitats, such as the mucus layer, and which defense mechanisms it can deploy to survive in these niches.

microbiology↗

bioRxiv2024

Bioengineering Fascicle-like Skeletal Muscle Bioactuators via Pluronic-Assisted Co-axial 3D Bioprinting

Advances in 3D bioprinting have opened new possibilities in the development of bioengineered muscle models that mimic the structure and functionality of native tissues. The combination of skeletal muscle tissue and artificial elements promotes diverse innovative solutions of interest in both the biomedical field and the development of biohybrid actuators. However, current bioengineering approaches do not fully recreate the complex fascicle-like hierarchical organization of skeletal muscle, impacting on the muscle maturation process due to a lack of oxygen and nutrients supply in the scaffold inner regions. Here we explored co-axial 3D bioprinting as a strategy towards overcoming this challenge, creating individual/non-fused filaments with controlled thickness that present a fascicle-like organization. Compared to conventional 3D-bioprinting, where cell-laden bioink is disposed by a single syringe, our Pluronic-assisted co-axial 3D-bioprinting system (PACA-3D) creates a physical confinement of the bioink during the extrusion process, effectively obtaining thin and independent printed fibers with controlled shape. Fabrication of skeletal muscle-based actuators with PACA-3D resulted in improved cell differentiation, obtaining stronger bioactuators with increased force output when compared to bioactuators fabricated by conventional 3D bioprinting. The versatility of our technology has been demonstrated using different biomaterials, showing its potential to develop more complex biohybrid tissue-based architectures with improved functionality.

bioengineering↗

bioRxiv2022

Improved performance of biohybrid muscle-based bio-bots doped with piezoelectric boron nitride nanotubes

Biohybrid robots, or bio-bots, integrate living and synthetic materials following a synergistic strategy to acquire some of the unique properties of biological organisms, like adaptability or bio-sensing, which are difficult to obtain exclusively using artificial materials. Skeletal muscle is one of the preferred candidates to power bio-bots, enabling a wide variety of movements from walking to swimming. Conductive nanocomposites, like gold nanoparticles or graphene, can provide benefits to muscle cells by improving the scaffolds mechanical and conductive properties. Here, we integrate boron nitride nanotubes (BNNTs), with piezoelectric properties, in muscle-based bio-bots and demonstrate an improvement in their force output and motion speed. We provide a full characterization of the BNNTs, and we confirm their piezoelectric behavior with piezometer and dynamometer measurements. We hypothesize that the improved performance is a result of an electric field generated by the nanocomposites due to stresses produced by the cells during differentiation, which in turns improves their maturation. We back this hypothesis with finite element simulations supporting that this stress can generate a non-zero electric field within the matrix. With this work, we show that the integration of nanocomposite into muscle-based bio-bots can improve their performance, paving the way towards stronger and faster bio-hybrid robots.

bioengineering↗

bioRxiv2017

Marine Fish Intestine Responds To Ocean Acidification Producing More Carbonate Aggregates

Marine fish contribute to the carbon cycle by producing mineralized intestinal aggregates generated as by-products of their osmoregulation. Here we aimed at characterizing the control of intestinal aggregate production in the gilthead sea bream in response to near future increases of environmental CO2. Our results demonstrate that hypercapnia (800 and 1200 atm CO2) elicits higher intestine epithelial HCO3- secretion and the subsequent parallel increase of intestinal aggregate production when compared to present values (400 atm CO2). Intestinal gene expression analysis revealed the up-regulation of crucial transport mechanisms involved not only in the intestinal secretion cascade (Slc4a4, Slc26a3 and Slc26a6) of sea bream, but also in other mechanisms involved in intestinal ion uptake linked to water absorption such as NKCC2 and the Aquaporin 1b. These results highlight the important role of fish in the marine carbon cycle, and their potential growing impact of intestinal biomineralization processes in the scenario of ocean acidification.

physiology↗