Jeevithan Elango

Disruption of the wound microenvironment by bacterial infection and excessive inflammation severely delays tissue repair, making multifunctional hydrogels that combine infection control and immune regulation highly desirable. Building on our previously reported carboxymethyl chitosan (CMC) hydrogel incorporating hyaluronic acid (HA) and RGD peptide (RGD), this study extended its evaluation to antibacterial activity, hemostatic behavior, and in vivo wound repair. Four formulations—CMC, CMC-HA, CMC-RGD, and CMC-HA-RGD—contained 1 wt% CMC with 0.9 wt% HA and/or 0.02 mg/mL RGD. Antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed by agar diffusion, while hemostatic behavior and wound repair were evaluated using mouse tail-transection and aseptically established full-thickness skin-wound models. Histology, immunohistochemistry, and serum enzyme-linked immunosorbent assays were used to assess tissue repair and inflammatory markers. CMC-HA-RGD produced inhibition-zone areas of 2.0 cm² against E. coli and 6.0 cm² against S. aureus. The RGD-containing formulations showed reductions in visible bleeding. Wound closure with CMC-HA-RGD reached 41.39%, 71.18%, and 95.56% on days 3, 7, and 14, respectively, compared with 16.47%, 58.18%, and 79.85% for CMC. Histology showed more complete epidermal–dermal architecture and denser collagen deposition. On day 14, relative to CMC, CMC-HA-RGD showed 35.37% and 37.74% lower interleukin-1β (IL-1β)- and tumor necrosis factor-α (TNF-α)-positive areas, respectively, while the collagen I-positive area increased from 63.36% to 72.58%. Serum interferon-γ (IFN-γ), IL-1β, and TNF-α concentrations were 9.08%, 18.01%, and 11.85% lower than those in the CMC group. Collectively, incorporating HA and RGD improved the antibacterial and hemostatic performance of the CMC hydrogel, attenuated local and systemic inflammatory responses, and promoted tissue remodeling, supporting its potential as a multifunctional wound dressing.

Background/Objectives: Marine microorganism metabolites are structurally unique secondary metabolites possessing therapeutic potential. The current study aims to identify a novel ATPase regulator using a newly established bidirectional activity evaluation system to screen for microbial metabolites that inhibit the activities of Na⁺-K⁺-ATPase or Ca²⁺-Mg²⁺-ATPase. Methods: A total of 1258 marine microbial strains were isolated from sea mud in Zhoushan, Zhejiang. Results: The extract of strain ZSDH2536 exhibited Na⁺-K⁺ and Ca²⁺-Mg²⁺-ATPase inhibitory activity and was identified as Sirastachys pandanicola based on morphological and molecular phylogenetic analyses. The secondary metabolite was tentatively identified in the ZSDH2536 strain as a bisindole compound, and named Pandanicoline based on ¹H-NMR, ¹³C-NMR and high-resolution mass spectrometry analysis. The chemical formula of Pandanicoline is C₅₁H₆₈N₂O₁₀, with an isotopic mass of 868.4874 Da. The maximum inhibition rate of Pandanicoline on Na⁺-K⁺ and Ca²⁺-Mg²⁺-ATPase was 36.37% and 37.27%, respectively. Moreover, in silico analysis also showed the binding energy of Pandanicoline with Na⁺-K⁺-ATPase was −9.124 kcal/mol and with the Ca²⁺-Mg²⁺-ATPase complex was −10.47 kcal/mol. Conclusions: The strain ZSDH2536 represents a promising source of dual inhibitors targeting Na⁺-K⁺ and Ca²⁺-Mg²⁺-ATPase. Pandanicoline exhibits potential as a lead compound for regulating ion homeostasis, providing new opportunities for further investigation into its mechanism and therapeutic applications.

Impaired wound healing is often caused by persistent inflammation, bacterial infection, and insufficient extracellular matrix remodeling. Natural polymer-based hydrogels represent ideal wound dressings but often struggle to balance structural stability and biological activity. Herein, we report a dual-functional network regulation strategy enabled by highly soluble mussel foot protein (HMFP) that acts simultaneously as a structural crosslinking regulator and bioactive effector to fabricate synergistic hydrogels (CS-SH-H) from β-chitosan (CS) and sodium hyaluronate (SH). HMFP homogenizes the porous microstructure, strengthens intermolecular interactions, and significantly improves thermal and structural stability via multivalent non-covalent bonding. In vitro, CS-SH-H shows excellent cytocompatibility, significantly promotes fibroblast proliferation and migration, and exerts potent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In a mouse full-thickness skin defect model, the hydrogel dramatically accelerates wound closure, reducing the residual wound area to 25% on day 7, outperforming the control groups. Immunohistochemistry confirms that HMFP suppresses TNF-α-mediated inflammation and enhances Ki-67-positive cell proliferation, leading to accelerated re-epithelialization and collagen deposition. This study establishes HMFP as a promising marine-derived dual-functional network regulator for designing high-performance hydrogel dressings. This strategy is scalable and translatable for treating infected and inflammatory wounds.

Marine by-products represent a promising source of bioactive peptides. This study aimed to isolate and characterize a low-molecular-weight peptide fraction with antioxidant activity from Argentine shortfin squid carcass by-products, and to evaluate in vitro its cytocompatibility and protective effects against corticosterone (CORT)-induced oxidative injury in rat adrenal pheochromocytoma (PC12) cells and human astrocyte (hACs) cells. Argentine squid antioxidant peptide (PASN) was obtained by size-exclusion chromatography and fractionation-based screening. PASN exhibited the strongest overall free-radical-scavenging activity and consisted predominantly of components below 1 kDa (211.73–1013.48 Da). Spectroscopic analyses indicated that enzymatic hydrolysis transformed its structure from a rigid triple-helix conformation to a more flexible conformation dominated by β-turns (50.78%) and random coils (17.38%). In addition, thermogravimetric analysis confirmed its excellent thermal stability, with an onset decomposition temperature as high as 244.81 °C, supporting its potential applicability in high-temperature food-processing matrices. In vitro assays demonstrated that PASN exhibited high biocompatibility and promoted proliferation of both PC12 cells and hACs, while significantly improving cell viability under CORT challenge. PASN also reduced lactate dehydrogenase (LDH) leakage (hACs: 38.31%; PC12: 31.17%) in both cell models and restored total superoxide dismutase (T-SOD) activity (hACs: 69.46%, PC12: 66.40%). Immunofluorescence further revealed that PASN rescued the expression of brain-derived neurotrophic factor (BDNF) (hACs: 35.23%, PC12: 12.50%) and glutamate decarboxylase (GAD1/2) (hACs: 102.66%, PC12: 31.31%), key markers associated with synaptic plasticity and GABAergic sleep regulation. Collectively, PASN is a thermally stable squid-derived peptide fraction that exerts antioxidant and cytoprotective effects in neural cell models in vitro and represents a promising sustainable candidate for nutraceutical development.

Although blood–brain barrier (BBB) models are of great value in investigating neurological diseases, the structural complexity and intricate function based on cell–cell interactions of the BBB bring various limitations to the applications of existing models. In this study, a novel BBB micro-organoid model was established by culturing neurovascular unit (NVU) cells on a decellularized squid mantle scaffold (DSMS) film to reconstitute a more authentic and reliable NVU microenvironment for in vitro research. The DSMS applied was obtained from squid mantle scaffolds via decellularization, followed by defatting, and showed good biocompatibility with no cytotoxicity. The DSMS film was finally prepared by lyophilization. The lyophilized film exhibited a void ratio and pore size suitable for the adhesion and growth of endothelial cells (hCMEC/D3) and astrocytes (hACs), which led to the formation of a BBB-like spatial structure. The BBB micro-organoid model exhibited functional barrier properties, including an effective transendothelial electrical resistance (TEER) of approximately 230 Ω/cm², restricted permeability to macromolecules—with apparent permeability coefficients (Papp) of 6.3 × 10⁻⁷ cm/s for 10 kDa and 2.7 × 10⁻⁷ cm/s for 70 kDa FITC–dextran—and expression of tight junctional complex (TJC) proteins such as vascular endothelial cadherin (VE-cad) and Zonula Occludens-1 (ZO-1). Furthermore, low-density lipoprotein receptor-related protein 1 (LRP1), a key receptor stably expressed in these two NVU cell types, was utilized as a critical indicator to assess the integrity of the BBB micro-organ model and its responsiveness to pathophysiological stimuli, particularly under thrombotic conditions. This study not only validates the feasibility of constructing a functionally competent BBB micro-organ model using DSMS films integrated with NVU cells but also provides a promising in vitro platform for subsequent studies on the BBB-related pathological mechanisms and the evaluation of drug permeability across the BBB.

Carboxymethyl chitosan (CMC)-based hydrogels have emerged as promising candidates for wound dressing applications due to their excellent biocompatibility and tunable physicochemical properties. In this study, a novel hydrogel functionalized with hyaluronic acid (HA) and RGD peptides (RGD) was fabricated and evaluated for its structural characteristics and wound-healing potential. Using CMC as the base matrix and EDC/NHS as crosslinking agents, four hydrogel variants were fabricated: CMC gel, CMC-HA gel, CMC-RGD gel, and CMC-HA-RGD gel. The preliminary cell compatibility experiment identified the optimal formulation as 1% CMC, 0.9% HA, and 0.02 mg/mL RGD, crosslinked with 1 vol% EDC and 0.05 wt% NHS. Scanning electron microscopy showed a porous architecture (100–400 μm), conducive to fibroblast viability and proliferation. Zeta potential measurements (|ζ| > 30 mV) indicated colloidal stability of the hydrogel system. Fourier-transform infrared spectroscopy confirmed successful crosslinking and integration of HA and RGD via hydrogen bonding and electrostatic interactions, forming a stable three-dimensional network. Thermogravimetric analysis revealed enhanced thermal stability upon HA/RGD incorporation. CCK-8 assays demonstrated significantly improved cell viability with HA/RGD loading (p < 0.05), while Ki-67 immunofluorescence confirmed enhanced fibroblast proliferation, with the CMC-HA-RGD gel showing the most pronounced effect. In vitro scratch assay results demonstrated that the CMC-HA-RGD hydrogel dressing significantly enhanced cellular migration compared to other carboxymethyl chitosan-based hydrogel groups (p < 0.05). The observed statistically significant improvement in cell migration rate versus controls underscores the distinctive enhancement of synergistic HA and RGD modification in accelerating cellular migration and facilitating wound repair. Collectively, these findings suggest that the CMC-HA-RGD hydrogel possesses favorable physicochemical and biological properties and holds strong potential as an advanced wound dressing for the treatment of chronic and refractory wounds.

Chronic inflammation is closely associated with various diseases, underscoring the need for natural, biocompatible anti-inflammatory candidates. For this purpose, mussel foot protein could be an excellent candidate due to its diverse biological activities. Hence, this study systematically evaluates the anti-inflammatory effects of a highly soluble mussel foot protein (HMFP) and HMFP-PEG using LPS-stimulated RAW264.7 cells as an in vitro inflammation model. The results reveal that both HMFP and HMFP-PEG markedly reduced intracellular reactive oxygen species (ROS) levels and suppressed the secretion of pro-inflammatory mediators, including IL-1β, TNF-α, and NO, while promoting the production of anti-inflammatory cytokines such as IL-10 and TGF-β. Mechanistically, both agents markedly inhibited the LPS-induced phosphorylation of PI3K, Akt, NF-κB, and IκB, indicating that their anti-inflammatory effects are mediated via suppression of the PI3K/Akt and NF-κB signaling pathways. Furthermore, HMFP and HMFP-PEG downregulated the expression of the inflammatory marker iNOS and markedly upregulated the M2 macrophage marker CD206, suggesting a role in promoting macrophage polarization toward an anti-inflammatory M2 phenotype. Notably, NF-κB signaling was identified as a key mediator in the anti-inflammatory mechanisms of both HMFP and its PEG-modified form. Collectively, these findings demonstrate that HMFP and HMFP-PEG exert significant anti-inflammatory effects through dual inhibition of NF-κB and PI3K/Akt signaling and by promoting M2 macrophage polarization, indicating their potential as promising candidates for the treatment of inflammation-related diseases.

Bioinks represent the core of 3D bioprinting, as they are the carrier responsible for enabling the fabrication of anatomically precise, cell-laden constructs that replicate native tissue architecture. Indeed, their role goes beyond structural support, as they must also sustain cellular viability, proliferation, and differentiation functions, which are critical for applications in the field of regenerative medicine and personalized therapies. However, at present, a persistent challenge lies in reconciling the conflicting demands of rheological properties, which are essential for printability and biological functionality. This trade-off limits the clinical translation of bioprinted tissues, particularly for vascularized or mechanically dynamic organs. Despite huge progress during the last decade, challenges persist in standardizing bioink characterization, scaling production, and ensuring long-term biomimetic performance. Based on these challenges, this review explores the inherent trade-off faced by bioink research optimizing rheology to ensure printability, shape fidelity, and structural integrity, while simultaneously maintaining high cell viability, proliferation, and tissue maturation offering insights into designing next-generation bioinks for functional tissue engineering.