Rare-earth-free magnesium (Mg) alloy bioresorbable stent (BRS) exhibits significant potential in vascular intervention due to its exceptional biosafety. However, its susceptibility to corrosion complicates surface functionalization and renders existing coating strategies ineffective for degradation-remodeling kinetics, resulting in delayed re-endothelialization and excessive lumen loss. Herein, a hierarchical MgF2/polyurethane (PU)/pitavastatin (PTV) coating system is constructed on Mg-Zn-Mn BRS using elastomeric PU as an intermediate layer. Studies confirm the PU layer effectively accommodates stent deformation, alleviates stress concentrations, and confines corrosion propagation triggered by deformation-induced MgF2 microcracks. The in situ formed MgF2 layer concurrently decreases substrate reactivity, establishes stable interfaces with PU, and synergistically enhances the corrosion resistance. The surface PTV-loaded poly-L-lactic acid layer maintains sustained drug release through PU-mediated interfacial stability while serving as an initial corrosion barrier. In vivo evaluations demonstrate the MgF2/PU/PTV-functionalized stent significantly suppresses neointimal hyperplasia in rabbit models while achieving synchronized degradation-remodeling kinetics. This hierarchical coating architecture, which synergistically integrates controlled drug elution with degradation modulation, provides a viable solution to clinical challenges of post-implant restenosis and vascular remodeling mismatch.

Nanoparticles in physiological environments acquire a biomolecular corona that defines their biological identity, mediating immune system recognition and accelerating blood clearance of the nanoparticles. Typically, low-fouling materials are chosen to minimize protein adsorption and thereby immune system responses, contributing to stealth in blood. However, absolute prevention of the biomolecular corona remains tantalizingly out of reach. Herein, it is proposed to leverage the biomolecular corona rather than preventing its formation, in order to overcome immune responses toward nanoparticles. Low-fouling and stealthy poly(ethylene glycol)(PEG) nanoparticles are used, with a functional biomolecular corona enriched with anticoagulant heparin-antithrombin III (HEP-ATIII) complexes that can mitigate undesirable immune responses. Through immune response evaluations and proteomic analyses are used to ascertain the low-fouling, stealthy character of the nanoparticles, similar to that of PEG nanoparticles. However, PEG nanoparticles alone induce coagulation responses in human blood, which are mitigated by pre-enrichment of the biomolecular corona with HEP-ATIII complexes. This shows that coagulation is another factor to be considered in the design of materials for nanomedicine and that the low-fouling and stealthy properties do not directly translate to hemocompatibility. These findings highlight the potential of biomolecular corona engineering to address key challenges in the field, toward developing safer, efficacious therapeutic nanomaterials.

Cell membrane coating has emerged as a promising strategy for the surface modification of biomaterials with biological membranes, serving as a cloak that can carry more functions. The cloaked biomaterials inherit diverse intrinsic biofunctions derived from different cell sources, including enhanced biocompatibility, immunity evasion, specific targeting capacity, and immune regulation of the regenerative microenvironment. The intrinsic characteristics of biomimicry and biointerfacing have demonstrated the versatility of cell membrane coating technology on a variety of biomaterials, thus, furthering the research into a wide range of biomedical applications and clinical translation. Here, the preparation of cell membrane coatings is emphasized, and different sizes of coated biomaterials from nanoscale to macroscale as well as the engineering strategies to introduce additional biofunctions are summarized. Subsequently, the utilization of biomimetic membrane-cloaked biomaterials in biomedical applications is discussed, including drug delivery, imaging and phototherapy, cancer immunotherapy, anti-infection and detoxification, and implant modification. In conclusion, the latest advancements in clinical and preclinical studies, along with the multiple benefits of cell membrane-coated nanoparticles (NPs) in biomimetic systems, are elucidated.

Implant-associated infections leading to osteolysis and implant loosening are an ongoing clinical challenge. Various strategies have been proposed to equip bone implants with antibacterial properties to prevent infection. However, the cytotoxicity associated with antimicrobial effects adversely impacts the osseointegration. Herein, a facile and safe strategy is proposed to endow bone implants with infection prevention, good cytocompatibility, inflammatory-responsive antimicrobial properties, thus promoting bone healing. The coating is fabricated on the implant through both covalent and non-covalent bonds of polyphenols with chlorhexidine (CHX). The covalent bonds guarantee long-term stability, while non-covalent bonds facilitate early release of CHX. Furthermore, the inclusion of polyphenols reduces the electrophilicity of CHX, inhibits reactive oxygen species generated by CHX, and minimizes interference with the mitochondrial electron transport chain, thereby reducing cellular toxicity. Consequently, the coating effectively fortified the bone implant, successfully impeding bacterial invasion within 7 days in Sprague-Dawley rats and suppressing inflammation as well as bone resorption caused by bacteria during a 60-day femoral implantation, thus facilitated osseointegration on the implant. The study investigated the cytotoxicity associated with mitochondrial interference induced by CHX and proposed a strategy to enhance its cellular compatibility, thereby providing a novel approach for fabricating biocompatible antibacterial bone implants.

Carotid atherosclerosis is an essential cause of transient cerebral ischemia, stroke, and other cerebrovascular diseases, and carotid endarterectomy (CEA) is currently the most effective treatment for removing plaque and restoring the vascular lumen. However, the CEA disrupts the integrity and functionality of the endothelium and predisposes it to complications such as restenosis and thrombosis. Hydrogels can closely mimic the natural extracellular matrix, allowing a wide tuning of physical and chemical properties. These properties make hydrogels the most promising candidate materials for the repair of vascular injured intima. In this study, a multifunctional intimal repair hydrogel of poly(ethylene glycol)-norbornene (PEGNB)/ Heparin/ Liposome is proposed with the advantages of ultra-rapid adhesion to the wet tissue of the vascular inner wall, maintenance of adhesion stability under continuous erosion by blood flow. The hydrogel was supplemented with poly(vinyl butyral) (PVB) to reduce its swelling rate, and Rapamycin (RAPA) was encapsulated in this study as the drug into the cationic liposomes. This composite multifunctional (PNHB@Lip(RAPA)) hydrogel has exhibited outstanding anti-coagulation properties, markedly suppressed the proliferation and migration of SMCs, and displayed favourable cytocompatibility and blood compatibility. Concurrently, the capacity of the PNHB@Lip(RAPA) hydrogel to stimulate endovascular regeneration and deter restenosis and thrombus formation was validated through carotid intima damage repair experiments. These findings collectively indicate that the PNHB@Lip(RAPA) hydrogel represents a promising material for intimal injury repair, offering innovative insights into intimal repair methodologies. STATEMENT OF SIGNIFICANCE: Carotid atherosclerosis is a leading cause of transient cerebral ischemia, stroke, and cerebrovascular disorders. Although carotid endarterectomy (CEA) effectively removes plaques, it damages endothelial integrity, increasing the risk of restenosis and thrombosis. To address this, we developed PNHB@Lip(RAPA), a multifunctional intimal repair hydrogel composed of PEGNB, heparin, and rapamycin-encapsulated liposomes. This hydrogel rapidly adheres to wet vascular walls, resists blood flow erosion, and exhibits low swelling. The hydrogel demonstrates superior anticoagulation, inhibits smooth muscle cell proliferation and migration, and shows favourable cytocompatibility. Experimental results confirm its ability to promote endovascular regeneration while preventing restenosis and thrombosis. In summary, PNHB@Lip(RAPA) hydrogel is a promising material for intimal repair, offering innovative solutions to improve CEA postoperative outcomes.

Microplastics (MPs) from environmental sources have been detected in various human organs, including the circulatory system. The biological response to such MPs is usually tested under artificial conditions, restricting their relevance. Probing the influence of MPs with realistic properties concerning size, shape, weathering-induced polymer degradation, and concentration on the response of human whole blood. This study examines the response of human whole blood to NPs of different cryomilled commodity polymers at a concentration range of 4 – 100 µg/ml, and mean size of about 25 µm, covering microplastic concentrations and size reported for organs and blood. Environmental degradation of the polymers was simulated through graded artificial weathering of the particles for 14 days in cyclic UV, temperature, and humidity changes, representing about 1.5 years of environmental weathering, and analyzed by Raman and Fourier transform infrared (FTIR) spectroscopy, and zeta potential measurement. Spectroscopic analysis of the bulk polymers indicated the degradation of aromatic polymers with the formation of carboxylic acid groups. Surface-sensitive zeta potential measurements also demonstrated a shift to more negative values of the polymers with aromatic groups. In contact with whole blood, these structural changes were associated with a pronounced coagulant response to the weathered polymers polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), and polyvinylchloride (PVC) containing aromatic plasticizers, compared to the pristine ones. There was a primary correlation with the changes in surface properties observed in the zeta potential shift. In the case of PET, these surface- and biological effects did exceed the changes in the FTIR and Raman spectra. A dose-dependency to the particle count and the intensity of weathering was observed. These findings underscore the impact of environmental weathering of common MPs on their biological performance.

Cell-instructive polymer hydrogels are instrumental in tissue engineering for regenerative therapies. Implementing defined and selective responsiveness to external stimuli is a persisting challenge that critically restricts their functionality. Addressing this challenge, this study introduces a versatile, modular hydrogel system composed of four-arm poly(ethylene glycol)(starPEG)-peptide and glycosaminoglycan(GAG)-maleimide conjugates. The gel system features a small peptide sequence that is selectively cleaved by the coagulation factor FXa. In a cell culture environment, where active FXa is absent, the hydrogel remains stable, providing a conducive matrix for the growth of complex tissue structures or organoids. Upon the introduction of FXa, the hydrogel is designed to disintegrate rapidly, enabling the gentle release of the cultivated tissues without impairing their functionality. The efficacy of this approach is demonstrated through the ex vivo development, detachment, and transplantation of human corneal endothelial lamellae, achieving sizes relevant for clinical application in Descemet Membrane Endothelial Keratoplasty (DMEK). Furthermore, the practicality of the hydrogel system is validated in vitro using a de-endothelialized porcine cornea as a surrogate recipient. Since the FXa-cleavable peptide can be integrated into a variety of multifunctional hydrogels, it can pave the way for next-generation scaffold-free tissue engineering and organoid regenerative therapies.

Adaptive drug release can combat coagulation and inflammation activation at the blood-material interface with minimized side effects. For that purpose, poly(styrene-alt-maleic-anhydride) copolymers were conjugated to heparin via coagulation-responsive linker peptides and shown to tightly adsorb onto poly(ethersulfone) (PES)-surfaces from aqueous solutions as monolayers. Coagulation-responsive release of unfractionated as well as low molecular weight heparins from the respective coatings was demonstrated to be functionally beneficial in human plasma and whole blood incubation with faster release kinetics resulting in stronger anticoagulant effects. Coated poly(ethersulfone)/poly(vinylpyrrolidone) (PES/PVP) flat membranes proved the technology to offer an easy, effective and robust anticoagulant interfacial functionalization of hemodialysis membranes. In perspective, the modularity of the adaptive release system will be used for inhibiting multiple activation processes.

Universal coatings with versatile surface adhesion, good mechanochemical robustness, and the capacity for secondary modification are of great scientific interest. However, incorporating these advantages into a system is still a great challenge. Here, we report a series of catechol-decorated polyallylamines (CPAs), denoted as pseudo-Mytilus edulis foot protein 5 (pseudo-Mefp-5), that mimic not only the catechol and amine groups but also the backbone of Mefp-5. CPAs can fabricate highly adhesive, robust, multifunctional polyCPA (PCPA) coatings based on synergetic catechol-polyamine chemistry as universal building blocks. Due to the interpenetrating entangled network architectures, these coatings exhibit high chemical robustness against harsh conditions (HCl, pH 1; NaOH, pH 14; H2O2, 30%), good mechanical robustness, and wear resistance. In addition, PCPA coatings provide abundant grafting sites, enabling the fabrication of various functional surfaces through secondary modification. Furthermore, the versatility, multifaceted robustness, and scalability of PCPA coatings indicate their great potential for surface engineering, especially for withstanding harsh conditions in multipurpose biomedical applications.

Hydrogel-based 3D cell cultures can recapitulate (patho)physiological phenomena ex vivo. However, due to their complex multifactorial regulation, adapting these tissue and disease models for high-throughput screening workflows remains challenging. In this study, a new precision culture scaling (PCS-X) methodology combines statistical techniques (design of experiment and multiple linear regression) with automated, parallelized experiments and analyses to customize hydrogel-based vasculogenesis cultures using human umbilical vein endothelial cells and retinal microvascular endothelial cells. Variations of cell density, growth factor supplementation, and media composition are systematically explored to induce vasculogenesis in endothelial mono- and cocultures with mesenchymal stromal cells or retinal microvascular pericytes in 384-well plate formats. The developed cultures are shown to respond to vasculogenesis inhibitors in a compound- and dose-dependent manner, demonstrating the scope and power of PCS-X in creating parallelized tissue and disease models for drug discovery and individualized therapies.

Endowing membranes with specific properties, often requires surface functionalization. However, coating processes are frequently time-consuming, expensive and limited in stability. Therefore, low-cost alternatives that offer a wide range of surface functionalization options are sought. This work presents poly(ether sulfone)/poly(vinyl pyrrolidone) (PES/PVP) membranes with blended poly(styrene-alt-maleic anhydride) (SMA)-copolymers, which covalently bind amine groups on the surface. Using this approach, an anchoring point for variable subsequent membrane functionalization with amine-bearing molecules was established and applied for an anticoagulant membrane decoration with heparin to increase the hemocompatibility of the membrane surface. Membranes prepared from PES/PVP polymer solution exhibited a stable integration of 0.05to 0.5wt.% SMA-copolymer in the membrane structure, both in buffer systems and biofluid. Zeta potential and fouling measurements showed a strong influence of the SMA-copolymers with decreased binding of albumin onto the membrane surface, while no significant change in morphology was detected for SMA-copolymer blended flat sheet and hollow fiber membranes. For further immobilization with aminated molecules, the reactive maleic anhydride groups were freshly activated by tempering, and functionalization occurred from an aqueous solution. The covalent binding was first validated using an amine-bearing fluorescence label, thereby showing the highest binding for membranes blended with 0.1wt.% SMA-copolymer. The potential of this functionalization platform was demonstrated by immobilization of aminated heparin for application as hemodialysis membranes. The heparin exhibited bioactivity on the membrane surface, while the mechanical properties were comparable to the reference membranes. Overall, the presented system offers a simple and cost-effective technology for a stable membrane functionalization with a broad range of applications.

BackgroundNeurointerventional devices, particularly laser-cut thin-strut stents made of self-expanding nickel-titanium alloy, are increasingly utilized for endovascular applications in intracranial arteries and dural venous sinuses. Preventing thrombosis and stroke necessitates systemic anticoagulant and antiplatelet therapies with the risk of bleeding complications. Antithrombotic coatings present a promising solution.MethodsIn this study, we investigated the potential of hydrogels composed of four-armed poly(ethylene glycol) (starPEG) and heparin, with or without coagulation-responsive heparin release, as coatings for neurovascular devices to mitigate blood clot formation. We evaluated the feasibility and efficacy of these coatings on neurovascular devices through in vitro Chandler-Loop assays and implantation experiments in the supra-aortic arteries of rabbits.ResultsStable and coagulation-responsive starPEG-heparin hydrogel coatings exhibited antithrombotic efficacy in vitro, although with a slightly reduced thromboprotection observed in vivo. Furthermore, the hydrogel coatings demonstrated robustness against shear forces encountered during deployment and elicited only marginal humoral and cellular inflammatory responses compared with the reference standards.ConclusionHeparin hydrogel coatings offer promising benefits for enhancing the hemocompatibility of neurointerventional devices made of self-expanding nickel-titanium alloy. The variance in performance between in vitro and in vivo settings may be attributed to differences in low- and high-shear blood flow conditions inherent to these models. These models may represent the differences in venous and arterial systems. Further optimization is warranted to tailor the hydrogel coatings for improved efficacy in arterial applications.

Glycogen, a naturally sourced highly branched polysaccharide nanoparticle, has been receiving attention in the field of nanomedicine due to its inherent non-toxicity and biodegradability. However, often in the literature glycogen nanoparticles (NPs) are used that come from different commercial sources (animals and tissues), which have significantly different sizes, molecular weights, and protein content, meaning a comprehensive overview of the interactions of these differently-sourced NPs with the human immune system is missing. Herein, we investigated coagulation, immune cell association and inflammation responses triggered by source-dependent interactions of glycogen NPs in human blood, utilising four types of commercially available glycogen: phytoglycogen (PG) isolated from sweet corn kernels, oyster glycogen (OG), rabbit liver glycogen (RLG), and bovine liver glycogen (BLG). Our results reveal that glycogen NPs exhibit minimal immune cell association, low complement factor, granulocyte, and platelet activation, and have no impact on blood clotting. This is despite the significant physico-chemical differences between the NP types, and when studied at exceptionally high particle concentrations (orders of magnitude higher than other typically studied synthetic systems). Given the similarities in the interactions with blood, either of the commercial glycogens can be leveraged in nanomedicine with respect to immuno-interactions, though PG provides a sustainable and ethically sourced form of NPs from plants. Together, our results highlight a key benefit of using glycogen NPs as injectable biomaterials for therapeutic applications.

Cellulose is an appealing material for tissue engineering. In an attempt to overcome some obstacles with cellulose II cell scaffolding materials related to insufficient biomineralization, lack of micron-size porosity, and deficiency in surface charge, respective solutions have been proposed. These included covalent phosphorylation of different cellulose materials targeting relatively low degrees of substitution (DS 0.18–0.23) and processing these cellulose derivatives into scaffolding materials by a dissolution/coagulation approach employing the hitherto rarely used TBAF/DMSO/H2O system for cellulose dissolution. Here, we report bioactivity and preliminary hemocompatibility testing of dual-porous cellulose phosphate aerogels (contrasted with the phosphate-free reference) obtained via coagulation (water/ethanol), solvent exchange and scCO2 drying. Deposition of hydroxyapatite from simulated body fluid (7 days of immersion) revealed good bioactivity (1.5–2.2 mg Ca2+ per mg scaffold). Incubation of the scCO2-dried and rehydrated scaffolding materials in heparin anticoagulated human whole blood was conducted to study selected parameters of hemostasis (prothrombin F1+2 fragment, PF4, count of thrombocyte-leukocyte conjugates) and inflammatory response (C5a fragment, leukocyte activation marker CD11b). Adhesion of leukocytes on the surface of the incubated substrates was assessed by scanning electron and fluorescence microscopy (DAPI staining). The results suggest that phosphorylation at low DS does not increase platelet activation. However, a significant increase in platelet activation and thrombin formation was observed after a certain fraction of the negative surface charges had been compensated by Ca2+ ions. The combination of both phosphorylation and calcification turned out to be a potent means for controlling the inflammatory response, which was close to baseline level for some of the studied samples.

Dataset to the publication A new in vitro blood flow model for the realistic evaluation of antimicrobial surfaces Juliane Valtin, Stephan Behrens, André Ruland, Florian Schmieder, Frank Sonntag, Lars D. Renner, Manfred F. Maitz, Carsten Werner

Hemocompatibility tuning was adopted to explore and refine an innovative, GA-free preparation strategy combining decellularization, riboflavin/UV crosslinking, and low-energy electron irradiation (SULEEI) procedure. A SULEEI-protocol was established to avoid GA-dependent deterioration that results in insufficient long-term aortic valve bioprosthesis durability. Final SULEEI-pericardium, intermediate steps and GA-fixed reference pericardium were exposed in vitro to fresh human whole blood to elucidate effects of preparation parameters on coagulation and inflammation activation and tissue histology. The riboflavin/UV crosslinking step showed to be less efficient in inactivating extracellular matrix (ECM) protein activity than the GA fixation, leading to tissue-factor mediated blood clotting. Intensifying the riboflavin/UV crosslinking with elevated riboflavin concentration and dextran caused an enhanced activation of the complement system. Yet activation processes induced by the previous protocol steps were quenched with the final electron beam treatment step. An optimized SULEEI protocol was developed using an intense and extended, trypsin-containing decellularization step to inactivate tissue factor and a dextran-free, low riboflavin, high UV crosslinking step. The innovative and improved GA-free SULEEI-preparation protocol results in low coagulant and low inflammatory bovine pericardium for surgical application.

Physiologically relevant in vitro hemocompatibility assessment of biomaterials remains challenging. We present a new setup that enables standardized whole blood incubation of biomedical materials under flow. A blood volume of 2 mL is recirculated over test surfaces in a custom-made parallel plate incubation system to determine the activation of hemostasis and inflammation. Controlled physiological shear rates between 125 s-1 and 1250 s-1 and minimized contact to air are combined with a natural-like pumping process. A unique feature of this setup allows tracing adhesion of blood cells to test surfaces microscopically in situ. Validation testing was performed in comparison to previously applied whole blood incubation methodologies. Experiments with the newly developed setup showed that even small obstacles to blood flow activate blood (independent of materials-induced blood activation levels); that adhesion of blood cells to biomaterials equilibrates within 5 to 10 min; that high shear rates (1250 compared to 375 s-1) induce platelet activation; and that hemolysis, platelet factor 4 (PF4) release and platelet loss - but not thrombin formation - depend on shear rate (within the range investigated, 125 to 1250 s-1).

Three-dimensional cell and organoid cultures rely on the mechanical support of viscoelastic matrices. However, commonly used matrix materials lack control over key cell-instructive properties. Here we report on fully synthetic hydrogels based on DNA libraries that self-assemble with ultrahigh-molecular-weight polymers, forming a dynamic DNA-crosslinked matrix (DyNAtrix). DyNAtrix enables computationally predictable and systematic control over its viscoelasticity, thermodynamic and kinetic parameters by changing DNA sequence information. Adjustable heat activation allows homogeneous embedding of mammalian cells. Intriguingly, stress-relaxation times can be tuned over four orders of magnitude, recapitulating mechanical characteristics of living tissues. DyNAtrix is self-healing, printable, exhibits high stability, cyto- and haemocompatibility, and controllable degradation. DyNAtrix-based cultures of human mesenchymal stromal cells, pluripotent stem cells, canine kidney cysts and human trophoblast organoids show high viability, proliferation and morphogenesis. DyNAtrix thus represents a programmable and versatile precision matrix for advanced approaches to biomechanics, biophysics and tissue engineering.