Biology subjects

Arral, M. L.

Publications and source records attributed to Arral, M. L..

4 recordsLinked to original sources

bioRxiv2026

Molecular Engineering of Silk via Fatty Acid Esterification for Water-Stable, Anti-fouling, Biocompatible, Implantable Materials

Biopolymers offer attractive properties for implantable materials, but their limited aqueous and enzymatic stability constrains long-term performance in biological environments. Silk fibroin is mechanically tunable and thermoplastically processable, yet remains susceptible to swelling in aqueous environments, which can impact mechanical properties. Here, we establish fatty acid esterification as a strategy to transform silk into a hydrophobic, water-stable, yet still bioresorbable material (FAsilk). Fatty acid functionalization significantly increased resistance to aqueous swelling and enzymatic degradation while preserving structural and mechanical integrity and thermoplastic processability. The resulting FAsilk biomaterials also reduced microbial contamination, blood clot formation, and macrophage adhesion relative to native silk, due to the change in hydrophobicity, while maintaining cytocompatibility and hemocompatibility. Subcutaneous implantation in mice demonstrated favorable biological responses, including minimal impact on body weight and no significant pro-inflammatory responses, indicating no adverse effects on animal health. Thus, fatty acid functionalization enables silk to combine hydrophobicity and aqueous stability with processability and biodegradability, providing a mechanically robust materials platform for bioresorbable implants, including medical devices, tissue-engineered grafts and drug delivery systems.

bioengineering↗

bioRxiv2026

Progressive matrix stiffening of tyramine-modified silk fibroin hydrogels governs stage-specific pulmonary fibroblast activation

Fibrosis is a progressive and often fatal pathological process characterized by excessive extracellular matrix deposition, tissue stiffening, and irreversible organ dysfunction. Effective antifibrotic therapies remain limited by the lack of in vitro models that recapitulate the full spectrum of fibrotic disease progression. Here, we leverage tyramine-modified silk fibroin (SF-TA) hydrogels to investigate normal human lung fibroblasts (NHLF) responses to progressively stiffening environments relevant to pulmonary fibrosis. Two hydrogel formulations with distinct stiffening profiles over 14 days were prepared: a gradual-stiffening 0% SF-TA formulation reaching [~]20 kPa, and a rapidly stiffening 50% SF-TA formulation reaching [~]60 kPa. NHLFs were cultured on both formulations, with and without TGF{beta} (5 ng/mL), for 14 days and assessed for viability, metabolic activity, cytokine and collagen secretion, cytoskeletal organization, and mechanotransductive gene expression. The 0% SF-TA hydrogels drove sustained fibroblast proliferation and elevated secretion of IL-6, IL-8, and MCP-1, consistent with early inflammatory fibrosis. The 50% SF-TA hydrogels induced a metabolic plateau without senescence, suppressed inflammatory cytokine secretion, and, in the presence of TGF{beta}, led to significant upregulation of ACTA2 and CTGF, alongside -SMA stress fiber incorporation, consistent with established myofibroblast persistence. Both conditions produced comparable secreted collagen output by day 14. Together, these findings establish dynamically stiffening SF-TA hydrogels as a tunable platform for investigating stage-dependent fibroblast activation and mechanobiological progression in fibrosis.

bioengineering↗

bioRxiv2024

Lipid Nanoparticle-Associated Inflammation is Triggered by Sensing of Endosomal Damage: Engineering Endosomal Escape without Side Effects

Lipid nanoparticles (LNPs) have emerged as the dominant platform for RNA delivery, based on their success in the COVID-19 vaccines and late-stage clinical studies in other indications. However, we and others have shown that LNPs induce severe inflammation, and massively aggravate pre-existing inflammation. Here, using structure-function screening of lipids and analyses of signaling pathways, we elucidate the mechanisms of LNP-associated inflammation and demonstrate solutions. We show that LNPs hallmark feature, endosomal escape, which is necessary for RNA expression, also directly triggers inflammation by causing endosomal membrane damage. Large, irreparable, endosomal holes are recognized by cytosolic proteins called galectins, which bind to sugars on the inner endosomal membrane and then regulate downstream inflammation. We find that inhibition of galectins abrogates LNP-associated inflammation, both in vitro and in vivo. We show that rapidly biodegradable ionizable lipids can preferentially create endosomal holes that are smaller in size and reparable by the endosomal sorting complex required for transport (ESCRT) pathway. Ionizable lipids producing such ESCRT-recruiting endosomal holes can produce high expression from cargo mRNA with minimal inflammation. Finally, we show that both routes to non-inflammatory LNPs, either galectin inhibition or ESCRT-recruiting ionizable lipids, are compatible with therapeutic mRNAs that ameliorate inflammation in disease models. LNPs without galectin inhibition or biodegradable ionizable lipids lead to severe exacerbation of inflammation in these models. In summary, endosomal escape induces endosomal membrane damage that can lead to inflammation. However, the inflammation can be controlled by inhibiting galectins (large hole detectors) or by using biodegradable lipids, which create smaller holes that are reparable by the ESCRT pathway. These strategies should lead to generally safer LNPs that can be used to treat inflammatory diseases.

bioengineering↗

bioRxiv2023

Lipid nanoparticle structure and delivery route during pregnancy dictates mRNA potency, immunogenicity, and health in the mother and offspring

Treating pregnancy-related disorders is exceptionally challenging because many small molecule drugs on the market may cause maternal and fetal toxicity. This potential danger has hindered the development and clinical evaluation of new drugs for several decades. Lipid nanoparticle (LNP)-based RNA therapies with high delivery efficacy, favorable immune response, and minimal transplacental transport can quell maternal-fetal toxicity concerns and propel the development of pregnancy-safe drugs. To this extent, we report potent LNP structures that robustly deliver mRNA to maternal organs and placenta. Using structure-function analysis, we show that LNP efficacy is influenced by the polyamine headgroup, and toxicity is governed by the acrylate tail. Our lead nanoparticle shows robust protein expression via multiple clinically relevant administration routes in pregnant mice. In the placenta, it transfects trophoblasts, endothelial cells, and immune cells. Further, by varying ionizable lipid structure, we demonstrate that LNP immunogenicity affects organ expression and pup health during pregnancy. Immunogenic LNPs show lower efficacy in lymphoid organs in an IL-1{beta} dependent manner in pregnant mice. Further, pro-inflammatory immune responses provoke the infiltration of adaptive immune cells in the placenta and restrict pup growth after birth. Together, our results provide a mechanistic basis for designing safe and potent LNPs that can be administered during pregnancy.

bioengineering↗