Bioactive Materials

This study aimed to develop a BMSC-laden polyethylene glycol diacrylate/methacrylated hyaluronic acid (PEGDA/HAMA) dual-crosslinked hydrogel and evaluate its effects on osteochondral defect repair. Two PEGDA concentrations, 3.75% and 7.5% (w/v), were used to prepare representative soft and stiff hydrogel formulations, respectively. The hydrogels were characterized in terms of morphology, cytocompatibility, and compressive behavior, and their ability to support BMSC-associated matrix deposition was evaluated in vitro. Repair outcomes were further assessed in a rat osteochondral defect model at 4 and 8 weeks. The 7.5% PEGDA/HAMA hydrogel exhibited higher stiffness than the 3.75% formulation and supported BMSC viability and matrix deposition in vitro. In vivo, the stiff hydrogel group showed improved defect filling and subchondral bone remodeling compared with the soft hydrogel and defect groups. However, histological and immunohistochemical analyses revealed predominant collagen type I deposition and limited collagen type II expression in the repair region, indicating fibrocartilaginous rather than hyaline-like cartilage repair. These findings suggest that BMSC-laden PEGDA/HAMA hydrogels may provide a useful platform for osteochondral defect repair, while further optimization of degradation behavior, matrix maturation, and collagen type II deposition is required to improve hyaline cartilage-oriented repair.

Traumatic cranial defects often involve concurrent loss of soft and hard tissues and can progress to chronic defects due to delayed healing associated with infection or other co-morbidities. Despite autologous reconstruction remaining the clinical standard, it requires staged procedures using heterogeneous tissues, increasing operative time, costs, and surgical risks. Moreover, current tissue engineering approaches focus on single tissues or acute tissue defect models, limiting their clinical applications. Herein, we describe an acellular, material-driven 3D-printed composite scaffold designed to regenerate both bone and skin within composite cranial defects. The scaffold integrates controlled copper ion release from both organic and inorganic components with 3D-printed citrate polymer and citrate polymer-ceramic composites. Integrated thermoresponsive citrate-based hydrogels further enable spatially defined dermoconductive and osteoconductive properties, supporting a one-step surgical approach. At 12 weeks post-implantation, our scaffold enhanced keratinocyte organization, collagen deposition, and defect coverage with mature bone, achieving histological outcomes comparable to autografts. Furthermore, the system suppressed bacterial burden. Thus, this acellular platform represents a clinically promising synchronized strategy to address the complex demands of traumatic craniofacial composite defects.

Chronic wound healing is often impaired in conditions such as metabolic syndrome, requiring effective therapeutic interventions to promote tissue regeneration and repair. In this study, we evaluated the wound healing potential of petroleum jelly (P Jelly)-based bioactive glass ointments (PBGCu) with varying copper concentrations (0, 1, and 3 wt%) in both in vitro and in vivo models of wound healing. PBGCu formulations demonstrated high biocompatibility with human dermal fibroblasts (HDF) and human umbilical vein endothelial cells (HUVEC). Additionally, PBGCu ointments exhibited strong antibacterial activity against Staphylococcus aureus, suggesting their utility for the care of chronic wounds. In both metabolic syndrome mouse and pig models, PBGCu3-treated wounds showed significantly faster wound closure, enhanced epithelial regeneration, and increased dermal thickness compared to saline and P Jelly controls. Histological analysis also revealed 50% increased vascularization (p < 0.0001) and a 90% reduction in scar formation (p < 0.0001) in PBGCu3-treated wounds. These findings show that PBGCu formulations, especially at 3 wt% copper concentration, significantly improve wound healing by promoting epithelial regeneration, dermal tissue formation, and vascularization, while also offering antibacterial protection. The sustained Cu2+ ions release from PBGCu ointments provides long-term support for tissue regeneration, positioning this ointment composition as a promising therapeutic tool for chronic wound management. Future studies will focus on elucidating the underlying mechanisms and evaluating the therapeutic efficacy of PBGCu formulations in infected wounds. HighlightsO_LIDeveloped a Petroleum Jelly-based copper-doped bioactive glass ointment (PBGCu) enabling sustained and controlled Cu{superscript 2} ion release. C_LIO_LIPBGCu significantly accelerated wound closure and improved epithelial and dermal tissue regeneration. C_LIO_LIPBGCu enhanced hair follicle regeneration and tissue remodeling in full-thickness wounds. C_LIO_LIValidated therapeutic efficacy in both mouse and pig models that support translational relevance. C_LIO_LIOffers a simple, low-cost, and clinically adaptable topical formulation for metabolic syndrome-related wound complications. C_LI

Significant challenges in spinal cord injury include the loss of neural tissue, disruption of local vasculature, and intrinsic suppression of actin mobilisation in neurons, together preventing axonal regrowth. Here, we develop an implantable biomimetic microRNA (miR) inhibitor-activated scaffold that combines optimised matrix cues with transcriptomically defined RNA-based modulation of intrinsic neuronal pathways as a platform to support neuronal cell delivery and promote neurovascular repair. First, hyaluronic acid macroporous scaffolds functionalized with collagen-IV and fibronectin supported iPSC-derived neuronal spheroid formation and neurite extension. To identify a neurotrophic target, we performed analysis of public miRNA-mRNA interaction datasets, revealing that miR-133a regulates pathways involved in neuronal actin cytoskeletal organisation. MiR-133a inhibitors were complexed with the cell-penetrating peptide RALA to form nanoparticles, demonstrated >95% scaffold loading efficiency, sustained localised release over 28 days and enhanced neurite outgrowth from motor neurons and iPSC neurons. Bulk RNA-sequencing and transcriptomic analysis of iPSC neurons within the scaffolds demonstrated coordinated upregulation of actin-remodelling, cell-matrix adhesion and metabolic pathways, indicative of a cytoskeletally adaptable neuron. When employed in an ex vivo dorsal root ganglia model, scaffold-mediated miR-133a inhibition promoted neurite extension and integration of delivered iPSC neurons with injured neural tissue. Finally, miR-133a-inhibitor-activated scaffolds upregulated neurovascular genes, increased endothelial cell migration and enhanced blood vessel formation in vivo in a chick embryo assay. These findings identify miR-133a as a neurotrophic target, elucidate the underlying mechanisms of action through transcriptomic analysis and demonstrate that biomimetic scaffold-mediated inhibition of miR-133a can enhance neuronal delivery for multifaceted spinal cord repair applications. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/719922v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@13fcb26org.highwire.dtl.DTLVardef@13239c3org.highwire.dtl.DTLVardef@6e6f5eorg.highwire.dtl.DTLVardef@51ad93_HPS_FORMAT_FIGEXP M_FIG C_FIG

Spinal metastases often occur secondary to breast, lung and prostate cancer and lead to instability, pain and poor quality of life. Standard care for spine metastases includes a multidisciplinary approach with surgery playing a major role in tumor resection, stabilization and decompression. Surgical resection with adjuvant is an effective treatment, yet it is often accompanied by tumor recurrence from residual disease. Furthermore, acrylic cements applied to defect sites provide stability, but they do not promote bone repair and can become destabilized during recurrence events. Developing new tools to stabilize defect sites, promote bone repair and locally deliver therapeutics may circumvent these limitations. We have previously developed mechanically competent 3D printed lactide/mineral scaffolds conducive to bone repair in vivo. We have also developed 3D printed nanoporous scaffolds conducive to both bone repair and chemotherapeutic delivery. Here, we set out to assess doxorubicin and cisplatin uptake and release rates and efficacy of drug delivery in 2D and custom physiological 3D cultures of two human cancer cell lines associated with metastases, MDA-MB-231 (human breast) and C42B (human prostate). Composite scaffolds had a compressive modulus close to trabecular bone, and could sustainably and effectively release doxorubicin and cisplatin as measured against both breast and prostate cell lines in 2D and 3D custom physiological metastases models. As a proof-of-concept, doxorubicin loaded composite scaffolds were implanted into rat caudal vertebrae following MDA-MB-231 xenograft resection. Following 6 weeks of implantation, no adverse events were noted and microCT analysis revealed boney integration of the construct. Taken together, these data indicate that our composite scaffolds may be an appropriate alternate therapy to stabilize bone defects, promote bone repair and effectively inhibit cancer recurrence post-tumor resection. Future work will test composite scaffolds using in vivo bone metastases models.

Critical-sized bone defects represent a challenge in bone tissue engineering, due to insufficient vascularization that results in implant failure. Scaffold pre-vascularization is a promising strategy to create a functional microvascular network that integrates with host vasculature. In this study, we present a hybrid 3D construct comprising a hyaluronic acid-based hydrogel and a 3D printed polycaprolactone/{beta}-tricalcium phosphate scaffold, to support vascular network formation and osteogenic differentiation. Peptide-functionalized (i.e. RGD, YIGSR, IKVAV, QK) hydrogels were obtained via thiol-ene chemistry, using two crosslinkers (PEG-diSH or MMP-diSH). Preliminary biological experiments assessed human mesenchymal stromal cells (hMSCs), endothelial cells (hUVECs), and their co-culture, on different gel formulations. All cell conditions displayed enhanced spreading and metabolic activity on gel formulations comprising RGD; thus these (i.e. RGD only and a combination of RGD/YIGSR) were selected for further studies. Cells were then mixed with the hydrogel precursor solutions, which were injected to embed the scaffolds and crosslinked using a UV lamp. After 7 days, tubule formation was observed only in co-culture conditions, highlighting the importance of cellular crosstalk for the formation of a vascular network. Significant differences were found across the tested formulations. In the RGD-PEG constructs, hUVECs formed tubule-like structures, surrounded by hMSCs, exhibiting pericyte-like behavior, supported by the upregulation of SMA gene. Conversely, in the RGD/YIGSR-MMP conditions, hMSCs were mostly located on the scaffold fibers, and showed the highest expression of early osteogenic markers (RUNX2 and ALP). Overall, we demonstrated that the hybrid system with tailored hydrogel chemistry can support simultaneous microvascular organization and osteogenic commitment, offering a promising platform for bone tissue engineering applications. However, further studies involving longer culture periods will aim at clarifying the complex interplay between material composition, cell crosstalk and spatial organization and their influence on the maturation and stability of the vascular network.

Tissue regeneration using bioactive biomaterials has made great progress in the field of wound healing. Biopolymers play a cardinal role in regenerative medicine by providing safe, biocompatible and bioresorbable support. The electrospinning fabrication technique has been used in creating suitable wound care materials. PHBV and PLLA are FDA approved polymers having important applications in biomedical field. In this study, to increase the wound healing potential, PHBV was functionalized with -COOH group and electrospun nano-fibrous mat was produced using PHBV-COOH and PLLA blended solution. Antibiofilm peptide (IDR-1018) with immunomodulatory activity was incorporated into the blended solution to improve infected wound treatment by actively fighting against bacterial infections. Furthermore, in-vitro experiments including cell cytotoxicity assay and scratch wound healing assay were done to evaluate the potential of the synthesized bioactive nanofibrous mat as a potential wound management aid.

Current biodegradable meshes for pelvic floor repair are constrained by a limited ability to actively modulate the hostile immune microenvironment following implantation. To address these challenges, we developed a functionalized degradable silk fibroin mesh (SFM) integrated with a reactive oxygen species (ROS)-responsive nanocomposite hydrogel. The resulting composite mesh, SFM@Gel-NP, features a "hydrogel-mesh-hydrogel" sandwich structure, wherein the hydrogel layers are loaded with self-assembled nanoparticles (NP-H-CRFP) for the co-delivery of the STING inhibitor H-151 and the ROS-scavenging agent catechin. This design provides immediate mechanical reinforcement while enabling microenvironment-triggered drug release. In vitro, NP-H-CRFP demonstrated efficient cellular uptake, significant ROS clearance, and effective attenuation of macrophage inflammation and apoptosis. In vivo, SFM@Gel-NP remodeled the local immune milieu by inhibiting the ROS/cGAS-STING/NF-{kappa}B axis, thereby promoting a shift from pro-inflammatory M1 toward pro-regenerative M2 macrophage polarization. This immunomodulatory effect, coupled with enhanced and well-organized collagen deposition--particularly of early type III collagen--resulted in improved tissue integration and repair. This work presents a novel strategy that combines structural reinforcement with active immune regulation, offering a promising next-generation solution for durable and functional pelvic floor reconstruction.

Vocal fold (VF) fibrosis is a major cause of persistent dysphonia due to excessive extracellular matrix deposition and tissue stiffening that disrupt normal vocal fold vibration. Current treatment approaches are limited by the need for repeated local injections and inadequate long-term therapeutic control. Pirfenidone (PFD), an FDA-approved antifibrotic agent, has demonstrated potential for reducing fibrosis; however, its short half-life and systemic adverse effects limit conventional administration strategies. In this study, we developed a sustained and near-infrared (NIR)-responsive local delivery platform by integrating PFD-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles into biodegradable PLGA implants for dose-controllable antifibrotic delivery. PFD-loaded PLGA nanoparticles were fabricated using an oil-in-water emulsion solvent evaporation method and characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Nanoparticles with small, medium, and large hydrodynamic diameters were generated to evaluate the effect of particle size on release behavior. Gold nanorods (AuNRs) were incorporated to enable photothermal NIR-triggered release enhancement. The nanoparticles were subsequently loaded into non-porous PLGA (90:10) implants and evaluated for long-term in vitro release under physiological conditions with and without pulsed 1064 nm laser irradiation. The nanoparticle-loaded implants demonstrated sustained PFD release for over 190 days with minimal initial burst release (<2.5%). NIR irradiation enhanced PFD release compared with non-irradiated controls across all nanoparticle sizes. Smaller nanoparticles produced greater cumulative release than medium and large nanoparticles due to shorter diffusion pathways and larger surface-area-to-volume ratios. Prior to implant fracture, cumulative PFD release reached approximately 20.2%, 14.8%, and 12.3% of total loading for small, medium, and large nanoparticle groups under 2-min irradiation conditions, respectively. Dialysis membrane studies further demonstrated that the PLGA capsule acted as an additional diffusion barrier that substantially prolonged release compared with nanoparticles alone. Overall, this study demonstrates a hybrid nanoparticle-in-implant strategy capable of providing sustained and irradiation-enhanced local PFD delivery with tunable release characteristics. These findings support the potential of biodegradable, dose-controllable implant systems for long-term management of vocal fold fibrosis while reducing the need for repeated interventions.

ABSTRACTThe repair of large bone defects remains a major clinical challenge, in part due to inadequate vascularization and poor integration of graft materials. Tissue engineering strategies that recapitulate the developmental process of endochondral ossification, whereby a cartilage template remodels into bone, have shown significant potential in pre-clinical models of large bone defect healing. However, successfully scaling these approaches to clinically relevant sizes will require the development of strategies to support the rapid vascularization of the graft following implantation in vivo. Here, mechanically reinforced templates were first fabricated by integrating hypertrophic cartilage microtissues derived from human mesenchymal stem/stromal cells (MSCs) within an osteoconductive 3D-printed polycaprolactone (PCL) framework coated with nano-hydroxyapatite (nanoHA). In vitro the cartilage microtissues fused and generated an extracellular matrix rich in sulphated glycosaminoglycans and collagen. To prevascularize these constructs, vascular microtissues derived from a co-culture of endothelial cells and MSCs were incorporated into a central channel within the construct, which generated a microvascular network within the graft in vitro. Following subcutaneous implantation, hypertrophic cartilage templates with ( vascular-channel group) and without ( empty-channel group) this central vascularized channel supported endochondral bone formation. Quantitative microCT and histological analyses revealed significantly greater remaining bone in the empty-channel group, whereas the vascular-channel group supported enhanced vascularization and remodeling of the graft in vivo. These findings support the continued development and testing of a modular biofabrication strategy that combine self-organizing hypertrophic cartilage and vascular microtissues with osteoconductive 3D-printed architectures to generate scalable, prevascularised hypertrophic cartilage templates for endochondral bone repair. Key-words: spheroids, microtissues, hypertrophic cartilage, vascularization, endochondral ossification, bone tissue engineering.

Ex vivo airway engineering approaches such as 3D bioprinting offer a promising strategy for generating functional airway replacements, but the fabrication of hollow, patient-specific proximal airway constructs using translationally relevant bioinks remains challenging. This study describes the development of biocompatible, polymer-blended human airway-derived decellularized extracellular matrix (AW-dECM) bioinks for engineering structurally and mechanically relevant airway tissues. An optimal formulation consisting of 30 mg/mL AW-dECM and nanofibrillar cellulose alginate conjugated to RGD supported the bioprinting of simple and complex hollow airway structures with mechanical properties comparable to native airways ([~]8-10 kPa). The bioinks also promoted primary human airway epithelial cell viability, adhesion, and differentiation into mucociliary and secretory phenotypes during 28 days of air-liquid interface culture. Furthermore, subcutaneous implantation in immunocompetent rats demonstrated excellent biodegradative stability and overall biocompatibility over 30 days. Collectively, these findings establish a foundation for improved physiological airway models and future tissue-engineered airway replacements.

Mesenchymal stem/stromal cells (MSCs) are key players in regenerative medicine due to their immunomodulatory properties and ability to promote tissue repair. However, their therapeutic efficacy is often limited by rapid clearance following transplantation. MSC spheroids have shown enhanced functional properties, and we hypothesize that encapsulating them within hydrogel microbeads could offer additional protection and improve their viability. In this study, we developed a novel droplet-based microfluidic protocol for human MSCs derived from the apical papilla (SCAP) encapsulation and In-Bead spheroid formation within alginate microbeads. Optimization of the protocol allowed the formation of MSC spheroids in alginate droplets overnight (In-Bead), before alginate cross-linking and retrieval of alginate beads loaded with MSC spheroids. SCAP were successfully encapsulated within 275 {micro}m alginate microbeads, forming spheroids of approximately 80 {micro}m in diameter. Encapsulated SCAP spheroids retained their immunomodulatory properties. The process was further optimized by incorporating nanomedicines into the alginate solution before the formation of droplets and then spheroids, forming thus hybrid beads (Sph.Beads/NP). Nanomedicines were loaded with NecroX-5, a necrosis inhibitor, to improve SCAP viability further. Live/Dead assays indicated a protective effect of the nanomedicines, supporting the potential of this system for advanced cell delivery in regenerative applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/732109v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@278324org.highwire.dtl.DTLVardef@12bad2org.highwire.dtl.DTLVardef@1a7489forg.highwire.dtl.DTLVardef@190e793_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstractA combination strategy enhancing MSC viability through spheroid formation, microencapsulation, and nanomedicine association achieved by microfluidic encapsulation with In-Bead spheroid formation. Created with BioRender

Rapid revascularization is critical to tissue graft survival, as delayed reperfusion drives tissue ischemia and compromises cell viability and graft function. Although bulk hydrogels have been explored for promoting vessel formation, vascularization remains too slow to prevent ischemic injury to grafted tissues, highlighting the need for biomaterial platforms that accelerate graft revascularization and reperfusion. In this study, we present granular hydrogel composites (GHCs), where interstitial space is filled with fibrin and collagen to provide a vasculogenic matrix environment. GHCs supported the assembly of embedded endothelial cells into interconnected, lumenized networks in vitro which anastomosed with host vasculature and were systemically perfused 7 days after implantation. Careful optimization studies revealed that GHCs formed from covalently interlinked, RGD-functionalized microgels of 115 {micro}m diameter best supported vascular network formation in vitro and intravascular blood perfusion in vivo. To test the utility of GHCs for the vascular integration of a demanding and therapeutically relevant parenchymal tissue, GHC-based ovarian tissue grafts were implanted in a murine xenograft model and successfully connected to host vasculature, restoring blood flow to embedded human ovarian tissues within 10 days post-implantation. Notably, endothelial cells seeded within GHCs formed viable vasculature without pre-culture. This work establishes GHCs as a biomaterial platform to rapidly connect parenchymal tissues to host vasculature, with broad translational potential across engineered tissue grafting applications.

This study focuses on the development of 3D culture model dedicated to liquid cancers drug screening. The challenge addressed was to effectively retain non adherent small cells within a 3D-scaffold with tailorable mechanical properties, while proposing a fast and effective tool for drug screening. To that aim, we developed a macroporous alginate-chitosan polyelectrolyte complex (PEC) scaffold combined with a low-viscosity alginate (LVA) cell seeding solution. We hypothesized that LVA could undergo in situ pore gelation via calcium ions retained from the PEC fabrication process, enabling effective retention and homogeneous cell distribution, leading to an improved platform for drug screening and personalized medicine. First, we evaluated scaffold suitability for LVA infiltration and gelation. Microtomography revealed a highly porous architecture (98%) enabling LVA homogeneous penetration and complete gelation within 30 min, as confirmed by SEM, microscopy, rheology, and micro-rheology. Next, we assessed cell retention and biocompatibility using primary human chronic lymphocytic leukemia (CLL) cells. LVA-assisted seeding increased cell density 2.6-fold compared to medium alone, with homogeneous distribution, >80% viability over 7 days, and preserved differentiation into nurse-like cells. Finally, we demonstrated a proof of concept for drug screening. The Alginate-PEC scaffold (A-PEC scaffold) supported both qualitative live/dead imaging and rapid quantitative viability measurement with the Alamar Blue assay. Drug responses reproduced microenvironment-dependent protection effects observed in vivo. This integrated scaffold and seeding method provides a promising 3D platform for in vitro liquid cancer studies and drug screening on patient-derived hematological cancer cells. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=67 SRC="FIGDIR/small/722037v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@9b71d4org.highwire.dtl.DTLVardef@14e1dd0org.highwire.dtl.DTLVardef@1876a56org.highwire.dtl.DTLVardef@15656bc_HPS_FORMAT_FIGEXP M_FIG C_FIG

Injury to the central nervous system (CNS) causes inflammation, cell death, and glial scar formation that inhibits tissue repair. Injectable hydrogels modified with extracellular matrix (ECM)-derived peptides can provide biochemical cues to promote neural tissue repair and serve as a vehicle to deliver therapeutics across the blood-spinal/blood-brain barrier in a minimally invasive manner. We developed an injectable hydrazone crosslinked hyaluronic acid-alginate (HA-Alg) hydrogel for neural tissue repair. We fabricated hydrogels with a range of polymer concentrations and evaluated their physicochemical properties to identify formulations that mimic the stiffness and viscoelastic properties of the CNS tissue environment. Hyaluronic acid was further modified with ECM-derived, cell-adhesive peptides (RGD and IKVAV) to enhance neuronal adhesion and viability. To evaluate the therapeutic potential of our hydrogel platform, we embedded mouse embryonic stem cell aggregates and differentiated them toward mature V2a interneurons. These interneurons are critical for relaying motor signals and represent a promising therapeutic cell population for treating spinal cord injuries. We demonstrated successful enrichment for V2a interneurons in HA-Alg hydrogels containing ECM-derived peptides. Interestingly, both our newly described HA-Alg and established crosslinked HA-HA hydrogels containing IKVAV peptides demonstrated significantly increased neurite length in interneuron enriched cultures compared to hydrogels without peptides. This study demonstrates that the addition of ECM-derived peptides is essential to support the neuronal adhesion and viability required for functional CNS tissue repair. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/729352v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@666b1aorg.highwire.dtl.DTLVardef@17d4borg.highwire.dtl.DTLVardef@1c8ece2org.highwire.dtl.DTLVardef@37fdd5_HPS_FORMAT_FIGEXP M_FIG C_FIG Statement of SignificanceDevelopment of injectable, peptide-modified hyaluronic acid alginate hydrogels to support neuronal maturation for central nervous system tissue repair.

The mechanical properties of the cellular microenvironment are key regulators of cellular physiology. Although the field of cancer mechanobiology has attracted attention, the availability of matrix systems with independently and precisely tunable mechanical properties remains limited. Our group previously developed a collagen gel with enhanced mechanical strength by cross-linking collagen molecules using a platinum complex. In this study, we investigated the tunability of the mechanical properties of the platinum cross-linked collagen gel (PCG) and demonstrated that mechanical parameters can be controlled by varying the amount of the platinum complex. In addition, we examined how matrix mechanical properties modulate the phenotypes of lung adenocarcinoma A549 cells using the collagen matrix. Although A549 cells exhibited significant morphological alterations on stiffer matrices, these changes were not accompanied by classical epithelial-to-mesenchymal transition (EMT). Instead, they were associated with the upregulation of diverse gene expression related to cancer malignancy. We focused on maternal embryonic leucine zipper kinase (MELK) whose gene expression increased on stiffer matrices. Consistently, A549 cells cultured on stiffer matrices displayed enhanced sensitivity to a MELK-targeting anticancer drug. These findings highlight the potential of the matrices with tunable mechanical parameters not only to provide variety of physiological microenvironment but also to advance anticancer drug screening when combined with gene expression analysis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/720034v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@419074org.highwire.dtl.DTLVardef@72ef67org.highwire.dtl.DTLVardef@1c36e17org.highwire.dtl.DTLVardef@170dc33_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIPlatinum cross-linked collagen gel enables independent tuning of compressive and shear elasticities. C_LIO_LICellular functions may be regulated by matrix mechanical parameters through distinct mechanisms. C_LIO_LICorrelation analysis between matrix mechanical parameters and cancer cell gene expression provides a rational strategy for therapeutic drug screening. C_LI

Critical-sized bone defects and implant-associated complications are often exacerbated by chronic inflammation, which compromises tissue repair and implant integration. Mesenchymal stromal cell (MSC)-derived extracellular vesicles have emerged as promising immunomodulatory nanotherapeutics; however, their clinical translation remains constrained by low yield, heterogeneity, and poor scalability. Here we present a bioengineered MSC-derived nanoghosts platform designed to overcome these translational barriers while enabling tunable osteoimmunomodulatory function. By coupling high-yield nanoghost fabrication with biomimetic MSC conditioning, we demonstrate that oxygen tension (5 or 21% O2) and 3D culture substrates (5 or 15 wt-% GelMA) can reprogram MSC immunophenotype. Nanoghosts generated under hypoxic and 3D conditions displayed enriched anti-inflammatory cargo, preserved MSC viability under inflammatory stress, and partially rescued osteogenic mineralization in the presence of pro-inflammatory cytokines. Together, these findings showcase MSC nanoghosts as scalable and bioactive immunoregulatory nanotherapeutic capable of modulating immune-bone crosstalk, providing a translational strategy to mitigate inflammation-driven impairment of bone regeneration and implant integration. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/724218v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1551655org.highwire.dtl.DTLVardef@12d3371org.highwire.dtl.DTLVardef@8c50bborg.highwire.dtl.DTLVardef@834a8_HPS_FORMAT_FIGEXP M_FIG C_FIG

Producing bone and cartilage in a controlled and localized manner remains a significant challenge in regenerative medicine. This study investigated the ability of keratin- and polyethylene glycol (PEG)-based degradable hydrogels to deliver bone morphogenetic protein 2 (BMP-2) and leukocyte cell-derived chemotaxin 1 (LECT-1; also known as chondromodulin-1) intramuscularly to induce ectopic tissue formation. Adult male CD-1 mice received intramuscular implants of keratin-PEG gels containing a fixed dose of BMP-2 and increasing amounts of LECT-1. After two weeks, implants and surrounding muscle were analyzed using computed tomography (CT) and histology. The results showed that BMP-2 is necessary for forming new bone and cartilage, whereas LECT-1 alone appeared to trigger muscle dedifferentiation without ossification or chondrogenesis. Co-delivery of BMP-2 and LECT-1 enhanced bone and cartilage formation in a dose-dependent manner: higher LECT-1 doses led to proportionally more ectopic cartilage (linear correlation, r2 {approx} 90%), while bone formation peaked at the third LECT-1 dose at approximately twice the volume of the BMP-2-only group. These findings indicate that muscle-resident cells may be capable of reverting and switching to mesenchymal lineages, recapitulating endochondral ossification. The platform offers a promising strategy for growing bone and cartilage autografts within skeletal muscle bundles.

Post-traumatic osteoarthritis (PTOA) is a progressive joint disease for which no disease-modifying osteoarthritis drugs (DMOADs) have been approved. Although injectable drug delivery systems can prolong therapeutic retention within the joint, it remains unclear whether local drug release kinetics influence disease-modifying efficacy. Here, we developed a modular platform of injectable supramolecular hydrogels using biocompatible, generally recognized as safe (GRAS) amphiphilic molecules and systematically engineered a range of degradation and drug release profiles. Using the cathepsin-K inhibitor L-006235 as a model DMOAD, we generated hydrogels with distinct release kinetics and evaluated their therapeutic performance in PTOA. Hydrogels exhibiting slower degradation and more sustained drug release like Sucrose Stearate (SS hydrogel) showed prolonged intra-articular retention and improved therapeutic outcomes. In a destabilization of the medial meniscus (DMM) mouse model, sustained-release formulations significantly reduced cartilage degeneration, preserved aggrecan expression, improved joint histopathology, and enabled effective monthly dosing. In contrast, formulations with faster degradation and release kinetics required more frequent administration to achieve comparable benefits. To our knowledge, this is the first study to establish local drug release kinetics as a critical determinant of disease-modifying efficacy in PTOA. This work provides one of the clearest demonstrations to date that engineering intra-articular release kinetics, rather than merely prolonging residence time, can improve disease-modifying outcomes. Our findings establish local release kinetics as a key design parameter for osteoarthritis therapeutics and highlight the potential of tunable supramolecular hydrogels for long-acting drug delivery.

Granular extracellular matrix (gECM)-based biomaterials commonly contain polymer components to improve scaffold cohesion and handling during fabrication and use. However, these polymer hydrogel components may dilute ECM content and increase fabrication and regulatory complexity. This study evaluated whether particle-only gECM wafers could serve as a simplified alternative to hydrogel-based gECM scaffolds while maintaining structural, mechanical, and biological performance. Decellularized human cartilage and skin tissues were processed and fabricated into three scaffold formats: gECM hydrogels, freeze-dried gECM hydrogel wafers, and freeze-dried particle-only gECM wafers. Across fabrication methods, scaffold swelling, volume fraction, and stiffness were strongly influenced by both tissue type and fabrication approach. gECM hydrogels exhibited the greatest swelling and lowest stiffness, while gECM wafers displayed higher volume fractions and greater mechanical stiffness. Notably, gECM particle-only wafers achieved performance comparable to gECM hydrogel wafers despite the absence of a secondary polymer network. Particle-only wafers also maintained swelling behavior and structural properties over 3 months of dry storage at room temperature, with only modest decreases in stiffness. In vitro studies showed sustained cell viability over 14 days on particle-only wafers, with chondrocytes infiltrating cartilage wafers and fibroblasts remaining primarily surface-localized on skin wafers. In addition, particle-only wafers remained cohesive during implantation into a bovine cartilage defect model. These findings demonstrate that particle-only gECM wafers can achieve structural integrity, mechanical performance, and cytocompatibility without the need for an additional polymer network, highlighting a simplified and ECM-rich biomaterial platform. By eliminating polymer carriers and enabling dry storage with preserved function, this approach supports the development of off-the-shelf, translationally accessible gECM particle-only wafers for tissue engineering applications.