Acta biomaterialia最新文献

The development of biomaterials that mimic native bone remains a major challenge in regenerative medicine. Here, we present a bioinspired platform using high-density collagen hydrogels with tunable mineral content. These engineered microenvironments promote rapid osteogenesis in vitro without osteogenic supplements and accelerate bone regeneration in vivo in critical-sized defects. By modulating mineralization, we demonstrate that early mechanosensitive signaling in human mesenchymal stem cells is linked to matrix stiffness and biochemical composition. Within two hours, focal adhesion formation decreased with increasing mineral content, and fully mineralized scaffolds significantly increased nuclear YAP1 localization. By 24 h, RUNX2 expression was markedly increased in fully mineralized scaffolds, with 40.7 ± 3.9% RUNX2⁺ nuclei (p < 0.0001), and this trend persisted at the gene expression level at 3 days. In a rat calvarial defect model, fully mineralized microgels significantly increased bone volume in males at 12 weeks (18.99 ± 2.66 mm³) compared to empty defects (11.60 ± 2.12 mm³, p = 0.0242), whereas females showed no added benefit of full mineralization. Two-way ANOVA confirmed significant effects of sex (p = 0.0006), treatment (p < 0.0001), and their interaction (p = 0.0158). Histological analyses confirmed osteoinductive behavior across all microgel groups and highlighted reduced scaffold degradation and limited cellular infiltration in mineralized conditions. Together, these results demonstrate that tunable intrafibrillar mineralization modulates early stem cell mechanosensing and osteogenic priming in vitro and drives sex-dependent regenerative outcomes in vivo, emphasizing the need to balance scaffold mechanics and degradation to suit the biological context and improve clinical outcomes. STATEMENT OF SIGNIFICANCE: This study introduces a strategy to fine-tune the properties of implantable materials for bone repair using microscale scaffolds with controlled mineral content. By adjusting composition at the nanoscale, our work identifies how early cellular responses can be directed to influence long-term healing. Importantly, the findings reveal that regenerative outcomes vary by sex, emphasizing the need to consider biological differences in biomaterial design. This work offers new insight into how tailored physical environments can guide tissue repair and highlights the potential for precision approaches in bone graft development.

Collagen fibres are essential for the load-bearing capacity of soft biological tissues, ensuring structural integrity and function. The repair process after injury often involves collagen remodelling, including reorganisation, synthesis, and degradation. When remodelling is unbalanced, degradation can lead to mechanical strength loss and tissue failure, as often seen after anterior cruciate ligament reconstruction. It is well established that enzymatic collagen degradation is modulated by levels of static strain, with relatively low and high strain magnitudes accelerating degradation rates compared to an intermediate minimum. However, in vivo, load-bearing tissues experience more often dynamic strain, and the impact of different magnitudes of cyclic strain on collagen enzymatic breakdown remains unclear. The present study investigated whether different levels of cyclic strain alter the susceptibility of collagen to enzymatic degradation by collagenases, and compared them to static strain. Decellularised porcine patellar tendons underwent various static and cyclic strain relaxation tests with or without bacterial collagenases. Consistent with prior findings, static strain elicited maximum protection at the heel point where stiffness increases. In contrast, dynamic strain accelerated degradation regardless of average strain, indicating a magnitude-independent mechanism under dynamic loading. Additionally, the dynamic degradation rate, unlike under static stretch, was relatively unaffected in the toe region, with a decreasing trend above the heel point. These findings suggest that optimising tissue recovery with controlled collagen degradation requires carefully selecting strain values based on the loading type. Such insights enhance our understanding of collagen remodelling and inform recovery strategies. STATEMENT OF SIGNIFICANCE: Tissue repair after injury involves collagen remodelling, where degradation plays an important role. Collagen enzymatic degradation is known to be affected by static strain. However, in vivo tissues experience dynamic strains, with unclear effects. We investigated how dynamic strain alters collagen enzymatic degradation in porcine patellar tendons. As shown previously, static strain protected collagen degradation at the heel point, whereas the present study provided new insight that dynamic strain increased the degradation rate relative to static strain at all strain values and that this effect trended to be less sensitive to strain levels. These results suggest that physiological strains influence collagen degradation differently under static and dynamic loading, offering insights that may guide targeted strain applications to improve healing.

Intracortical microelectrodes (IMEs) are an integral component of brain computer interfaces (BCIs) designed to study and treat neurological disorders. Unfortunately, IMEs tend to fail prematurely due in part to the macrophage-mediated inflammation in response to implantation injury and the persistent foreign body reaction. Previous work has established that cluster of differentiation 14 (CD14) is implicated in the neuroinflammatory response to IME implants. CD14 is a conserved damage-associated coreceptor that facilitates immune activation in the presence of inflammatory damage-associated stimuli. We sought to mitigate the inflammatory response to IME implantation by suppressing CD14 expression on macrophages using a lipid nanoparticle (LNP) loaded with Cd14-specific siRNA. We tested the efficacy of the LNP-mediated gene delivery in cultured murine macrophages and in an in vivo mouse model with IME implants. Our in vitro findings indicated that the LNPs suppress inflammatory cytokine secretion. The in vivo studies showed efficient targeting of the LNPs to the desired cell populations with the majority of LNPs found in blood-circulating macrophages and infiltrating macrophages at the intracortical implant site. Our results show that the LNPs efficiently silence expression of the targeted Cd14 gene. Suppression of the CD14 protein led to reduced infiltration of immune cells to the brain parenchyma, as well as a significant decrease of the inflammatory response to implantation within the first 24 h after implantation, as determined by flow cytometry and transcriptomics. Together our results suggest that LNP-mediated gene therapy can specifically regulate one of the dominant drivers of the innate immune response to IME implantation. STATEMENT OF SIGNIFICANCE: Brain-computer interfaces rely on implanted electrodes to record and stimulate neural activity, but these devices often fail early because the body mounts an inflammatory immune response against them. Here, we focused on a central immune receptor, CD14, as a key driver of the inflammatory response to implants. Using lipid nanoparticles to deliver gene-silencing RNA, we were able to suppress CD14 expression in macrophages both in culture and in a mouse model with implanted electrodes. This targeted approach reduced immune cell infiltration and inflammation around implants. Our findings demonstrate that lipid nanoparticle-mediated gene therapy can selectively weaken the brain's innate immune response to implants, offering a promising strategy to improve the longevity and performance of neural interfaces.

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest solid tumors and is characterized by aggressive progression, a dense tumor microenvironment (TME), and resistance to conventional therapies. Among the barriers to effective treatments, the presence of elevated interstitial fluid pressure (IFP) may be important for drug penetration and immune cell infiltration. In this work, we present an innovative 3D microfluidic PDAC-on-a-chip that allows the application of IFP in a cell chamber to simulate the TME and evaluate the therapeutic efficacy of CAR-T cells engineered against the tumor receptor EGFR. Elevated IFP was associated with increased tumor spheroid growth, reduced caspase activation and decreased actin remodeling, indicating enhanced tumor resistance. CAR-T cells effectively targeted and eliminated tumor cells in 2D and 3D coculture models under normal pressure conditions. However, under high IFP, CAR-T-mediated cytotoxicity was impaired, indicating that some of the low efficacy of CAR-T-cell therapy against solid tumors might be derived from IFP. These results highlight the importance of the mechanoenvironment in limiting the efficacy of current immunotherapies. Our model, which incorporates an IFP component, serves as a realistic preclinical platform for testing antitumor therapies in solid tumors. Statement of significance In this work, we present an innovative 3D pancreatic tumor-on-a-chip model that incorporates interstitial fluid pressure (IFP), which is a key mechanical component of solid tumors. Using this platform, we discovered that IFP enhances tumor proliferation whilst diminishing immunotherapy efficacy. This indicates the important role of mechanical pressure in limiting immune cell function in solid tumors. Our model is a valuable preclinical platform for investigating the efficacy of anti-tumour therapies and supports the development of strategies to overcome mechanical resistance and enhance therapy efficacy in solid tumors, such as pancreatic cancer.

The escalating challenge of chemoresistance in breast cancer treatment severely limits clinical efficacy, necessitating the urgent development of innovative strategies that synergistically enhance tumor cell eradication and remodel the anti-tumor immune microenvironment. To address this, we developed a D-A structured theranostic probe, 1HA4CD, featuring a dihydroxanthene-fluorophore with diethylamino donor and acrylonitrile/pyridyl acceptors. Upon laser irradiation, 1HA4CD enables spatiotemporally controlled reactive oxygen species (ROS, primarily singlet oxygen, ¹O₂) generation. Crucially, its precise nuclear localization facilitates the induction of high-concentration ROS within the nucleus, causing irreversible oxidative genomic DNA damage. RNA sequencing analysis revealed that the transient nuclear ROS overload not only directly induces DNA double-strand breaks (DSBs) but also inhibits DNA repair pathways, creating a "dual-hit" effect that effectively overcomes the chemoresistance associated with traditional DNA-damaging agents through a nuclear-targeted photodynamic mechanism. DNA fragments released into the cytoplasm post-damage are recognized by the cytosolic DNA sensing machinery, subsequently activating the cGAS-STING signaling cascade, which leads to the systemic activation of both innate and adaptive immune responses. In vivo animal studies demonstrated that 1HA4CD-mediated photodynamic therapy exhibits significant therapeutic efficacy against breast cancer, coupled with a favorable biosafety profile. This research presents a nuclear-targeted molecular tool for photodynamic immune activation therapy and advances the development of combination therapies based on DNA damage-induced immune responses. STATEMENT OF SIGNIFICANCE: Photodynamic therapy (PDT) often suffers from limited efficacy due to insufficient subcellular targeting and the inability to induce systemic anti-tumor immunity, especially in chemoresistant cancers. This work presents 1HA4CD, a nuclear-targeting probe designed to enhance PDT by generating spatiotemporally controlled ROS directly within the nucleus. This approach causes direct DNA double-strand breaks while concurrently inhibiting DNA repair, and further activates the cGAS-STING pathway via damaged nuclear DNA fragments, thereby bridging localized photodamage with systemic immune activation. The resulting "dual-hit" mechanism effectively addresses chemoresistance in breast cancer. By integrating precise subcellular targeting with immunomodulation, this study provides a rational strategy for developing bioactive materials that combine PDT with immunotherap.

Dental caries is a multifactorial and dynamic disease primarily mediated by biofilm formation, resulting in a disruption of plaque microecological homeostasis and an imbalance in demineralization/remineralization of dental hard tissues. The development of antibacterial/remineralizing composite materials may help restore this balance. However, anticaries products that can mimic the amelogenesis process to achieve enamel remineralization and possess antimicrobial property are lacking. In this study, bovine serum albumin (BSA)-loaded ethylpyridinium chloride (CPC) was successfully used to form a BSA-CPC complex through H-bonding, van der Waals forces and electrostatic attraction. Subsequently, through fast amyloid-like aggregation, the phase-transitioned BSA (PTB)-CPC stabilized the amorphous calcium phosphate (ACP) to generate an ACP@PTB-CPC hydrogel. Next, 1% sodium hypochlorite (NaClO) was used to partly degrade this hydrogel and induce enamel remineralization. Herein, a biomimetic system of amelogenesis composed of the ACP@PTB-CPC hydrogel and NaClO was constructed, which mimics the gel-like microenvironment of amelogenesis, the amyloid-like structure of amelogenin, and the whole process of the three "key events" in the amelogenesis process. Compared with fluoride, this hydrogel has significant remineralization ability both in vitro and in vivo. Additionally, the application of the ACP@PTB-CPC hydrogel effectively inhibited the growth, adhesion and biofilm formation of Streptococcus mutans. In conclusion, the ACP@PTB-CPC hydrogel with remineralizing and antibacterial properties serves as an alternative therapy for preventing or arresting caries. STATEMENT OF SIGNIFICANCE: 1. Construction of An Amyloid-based Hydrogel: Using PTB as a fundamental framework, CPC was loaded and subsequently coassembled with ACP to obtain an amyloid-based hydrogel--ACP@PTB-CPC. 2. Biomimetic Amelogenesis Process: A biomimetic system of amelogenesis composed of ACP@PTB-CPC hydrogel and NaClO was constructed. 3. Potential for Clinical Application: A bifunctional anticaries material with remineralizing and antibacterial ability was developed, representing a promising alternative therapy of preventing and arresting enamel caries.

Cellular therapies involving the co-delivery of cells with complementary pro-regenerative functionality hold promise as a strategy to promote soft tissue augmentation and regeneration. In particular, the co-delivery of adipose-derived stromal cells (ASCs) and endothelial colony-forming cells (ECFCs) has shown promise for regenerating stable blood vessels in vivo. The current study developed "cell-assembled" scaffolds for co-delivering human ASCs and ECFCs within a supportive decellularized adipose tissue (DAT) matrix, with the objective of enhancing their localized retention and augmenting their capacity to stimulate adipose tissue regeneration. Human ASCs and ECFCs were seeded separately onto human-derived DAT microcarriers under cell-type specific conditions. The cell-seeded microcarriers were then combined and cultured for 8 days under conditions that promoted matrix remodeling to fuse the microcarriers into 3D engineered tissues containing ASCs+ECFCs, ASCs alone, or ECFCs alone. Co-culture with ECFCs within the scaffolds was shown to modulate ASC pro-angiogenic gene expression, with some ECFCs forming tubule-like structures in vitro in both the ASC+ECFC and ECFC alone groups. In vivo bioluminescence imaging using a dual luciferase reporter system showed that co-delivery with ASCs enhanced ECFC retention following subcutaneous implantation in athymic nu/nu mice, but co-delivery did not alter the localized retention of viable ASCs. Interestingly, while immunofluorescence staining for CD31 and microcomputed tomography angiography indicated that vascular regeneration was similar in the cell-assembled scaffolds containing ASC+ECFCs, ASCs alone, and ECFCs alone, histological staining revealed that extensive regions of the ECFC alone scaffolds had remodelled into adipose tissue at 29 days post-implantation. STATEMENT OF SIGNIFICANCE: Cellular therapies involving the co-delivery of complementary pro-regenerative cell types hold promise as a strategy to promote soft tissue regeneration. In particular, the co-delivery of adipose-derived stromal cells (ASCs) and endothelial colony forming cells (ECFCs) may enhance blood vessel regeneration in vivo, as well as promote ASC engraftment and adipogenic differentiation. The current study developed a modular bottom-up fabrication approach for generating "cell-assembled" scaffolds incorporating both human ASCs and ECFCs dispersed throughout a supportive human decellularized adipose tissue (DAT) matrix, which were compared to scaffolds incorporating ASCs alone or ECFCs alone. Co-delivery modulated ASC pro-angiogenic gene expression in vitro and enhanced viable ECFC retention in vivo, but interestingly, in vivo adipogenesis was augmented in the cell-assembled scaffolds incorporating ECFCs alone.

Acquired drug resistance in hepatocellular carcinoma (HCC) hinders the clinical therapeutic efficacy of various drugs, but efficient intervention strategies remain scarce. In this study, we reported a coacervate-fusion strategy for inhibiting membraneless organelle stress granules (SGs) via stimuli-induced peptide droplets to reverse sorafenib resistance (SFR) in HCC. SGs are coacervated from translation-stalled mRNAs and RNA-binding proteins, including Ras-GAP SH3 domain-binding proteins (G3BPs), and play a critical role in SFR. The peptide droplets YsF-L^SG are formed by liquid-liquid separation (LLPS) of the sulfatase-responsive peptides YsF and YsF-FGDF containing the G3BP ligand. Characterizations in solution reveal that, upon exposure to arylsulfatase A (ARSA), the peptides YsF and YsF-FGDF undergo LLPS and form agglomerate droplets YsF-L^SG. Investigations of HCC-SFR cells confirm that the YsF-L^SG mixtures are efficiently internalized via clathrin-mediated endocytosis, experience ARSA-responsive hydrolysis in lysosomes and lysosomal escape, and undergo in situ LLPS into droplets. Notably, in situ-formed coacervates YsF-L^SG recruit G3BP2 and target SGs with high tumor permeability. YsF-L^SG coacervates enhance sorafenib-triggered apoptosis by relieving SGs-mediated inhibition of p38-Caspase-3 signaling and thus reversing SFR of HCC cells. Further investigations in HCC cell-derived xenograft (CDX) models confirm that YsF-L^SG peptide coacervates significantly reverse SFR through SGs-targeting and apoptosis-restoring mechanisms. Critically, the combination of the YsF-L^SG peptide coacervates with sorafenib more effectively inhibits HCC-SFR growth and has a stronger antitumor effect accompanied by good biosafety. This study highlights the reversal of HCC-SFR via fusion between internal and external coacervates, offering a new approach for overcoming cancer drug resistance. STATEMENT OF SIGNIFICANCE: Design and application of peptide-based coacervates targeting SGs to overcome drug resistance have rarely been studied. Combining the advantages of in situ formulation of coacervate peptide droplets with SGs-targeting property, we developed YsF-L^SG peptide mixtures that target SGs through in situ sulfatase-responsive LLPS into droplets for reversing the SFR of HCC. YsF-L^SG peptide mixtures present high tumor-permeability and SGs-coalescence potential, undergo CME-involved uptake, experience ARSA sulfatase-responsivity and lysosomal escape, and exhibit potent tumor-killing advantage in HCC-SFR cells and CDX mice model. YsF-L^SG peptide mixtures reverse SFR of HCC through G3BP2-recruited, SGs-targeting and apoptosis-restored mechanisms. This provides a new strategy for developing enzyme-induced LLPS peptide coacervates with drug resistance-reversal capacity.

Gasdermin-mediated pyroptosis has emerged as a promising mechanism in cancer immunotherapy, however, its efficacy is often limited by inefficient activation within the immunosuppressive tumor environment. Herein, we generated an acid-regulating biomimetic liposomal nanovesicle (L-P-Cn-U) for the co-delivery of a photosensitizer prodrug (P-Cn) and a carbonic anhydrase IX (CAIX) inhibitor (U-104). By conducting efficacy screening of various P-Cn prodrugs within the L-P-Cn-U system, we identified L-P-C16-U with identical lipid tail structures, as the optimal candidate due to its strong colloidal stability and reactive oxygen species (ROS) generation efficiency. Our cellular and murine model studies demonstrated that L-P-Cn-U-mediated pyroptosis and immunogenic cell death could convert immunologically cold tumors into hot tumors, thereby enhancing antitumor immunity and concurrently inhibiting tumor cell migration. Mechanistic investigation revealed that the acid-triggered U-104 release from L-P-Cn-U augmented intracellular acidity through CAIX inhibition, which subsequently attenuated PI3K-Akt/mTOR signaling. This result enhances O₂-dependent ROS production and establishes a negative feedback loop for CAIX expression. Collectively, our findings provide a combinatorial strategy that integrates pyroptosis-focused therapy with metabolic regulation, offering a broadly applicable conception to augment cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Herein, we report the rational design and synthesis of a new class of biomimetic liposome by integrating chemically engineered pH-responsive lipids (L-pH) with lipid-like photosensitizer prodrugs (P-Cn). Characterization studies demonstrated an optimal construct (L-P-C16) with identical lipid tails, showing robust stability and reactive oxygen species production. This optimized nanovesicle was subsequently co-loaded with the carbonic anhydrase inhibitor U-104. The resulting L-P-C16-U system was adequately investigated and shown to effectively synergize photodynamic therapy and immunotherapy. Our work provides new insights into liposome engineering strategies for combination tumor therapy.

Accurate assessment of inflammatory bowel disease (IBD) severity is crucial for optimizing treatment decisions and improving prognosis. However, conventional assessment methods are time-consuming and primarily detect anatomical changes at moderate or late stages, limiting timely intervention. Here, we report an HClO‑responsive NIR‑IIb ratiometric nanosensor (CSSS@PMH‑mPEG2000) that combines down‑conversion core-shell nanoparticles with strong NIR‑IIb emission under 808/980 nm excitation and an HClO‑responsive IR780MA dye. By means of dye sensitizing mechanism, the sensor enables dynamic ratiometric quantification of HClO and supports real-time assessment of IBD progression and severity. Comprehensive in vitro and in vivo studies validate CSSS@PMH‑mPEG2000 as a highly sensitive and reliable platform for real-time, quantitative HClO monitoring of IBD in a mouse model. Moreover, ratiometric NIR‑IIb fluorescence imaging effectively captures changes in disease severity, highlighting its potential for assessing treatment efficacy. Together, these findings underscore the translational value of CSSS@PMH‑mPEG2000 for advancing IBD diagnosis and management, while also demonstrating its broader applicability to in situ HClO detection across a range of inflammatory diseases. STATEMENT OF SIGNIFICANCE: Accurate IBD severity assessment is vital for optimizing treatment and prognosis, but conventional methods are time‑consuming and detect mainly mid‑to‑late anatomical changes, delaying intervention. We present an HClO‑responsive NIR‑IIb ratiometric nanosensor (CSSS@PMH‑mPEG2000) combining down‑conversion core-shell nanoparticles with an HClO‑responsive IR780MA dye. Using dye sensitizing mechanism, it enables dynamic ratiometric HClO quantification and real‑time evaluation of IBD progression and severity. In vitro and in vivo studies in a mouse IBD model demonstrate high sensitivity and reliability for real‑time, quantitative HClO monitoring. Ratiometric NIR‑IIb imaging captures disease‑severity changes and supports treatment‑efficacy assessment, underscoring the platform's translational value for IBD management and broader in situ HClO detection in inflammatory diseases.