Heparin reduced dialysis through a facile anti-coagulant coating on flat and hollow fiber membranes

Mytilus edulis foot protein mimics for tailoring long-acting endothelium-mimicking anti-thrombotic surfaces

Surfaces with enduring and superior antithrombotic properties are essential for long-term blood-contacting devices. While current surface engineering strategies integrating anticoagulants and antiplatelet agents show promise in mimicking the non-thrombogenic properties of the endothelium, their long-term effectiveness remains limited. Here, we report an easy-to-perform, dual-biomimetic surface engineering strategy for tailoring long-acting endothelium-mimicking anti-thrombotic surfaces. We first designed a Mytilus edulis foot protein-5 (Mefp-5) mimic rich in amine and clickable alkynyl groups to polymerize-deposit a chemical robust coating onto the surface through a mussel-inspired adhesion mechanism. Then, a clickable nitric oxide (NO, an antiplatelet agent)-generating enzyme and the anticoagulant heparin were sequentially co-grafted onto the chemical robust coatings via click chemistry and carbodiimide chemistry. Our results demonstrate that this engineered surface achieved an impressive NO catalytic release efficiency of up to 88 %, while heparin retained 86 % of its bioactivity even after one month of exposure to PBS containing NO donor. Both in vitro and in vivo experiments confirmed that this robust endothelium-mimicking coating substantially reduces thrombosis formation. Overall, our long-acting endothelium-mimicking anti-thrombotic coatings present a promising and feasible strategy to address thrombosis-related challenges associated with blood-contacting devices.

Heparin and heparin-like modifications in hemodialysis membranes: Current innovations and future directions

Heparinized hemodialysis membranes represent a significant advancement in improving the biocompatibility and anticoagulant properties of dialysis treatments. This review explores the current challenges and innovations in developing these membranes, focusing on the incorporation of heparin and heparin-like substances to reduce protein adsorption, platelet adhesion, and clot formation. The methods for heparin immobilization, including covalent bonding, layer-by-layer assembly, and blending, offer promising results in enhancing membrane performance. However, issues such as long-term stability, large-scale production, and cost-effectiveness remain critical barriers to their widespread adoption. The review also highlights the role of surface activation techniques and nanotechnology in improving the functionality of heparinized membranes. Advanced methods like plasma treatment and polymer grafting provide better heparin attachment, while nanomaterial integration allows for improved blood compatibility and controlled heparin release. Despite these innovations, challenges such as heparin degradation, uneven coating, and the complexity of scaling up remain unresolved. Future research should focus on optimizing heparin distribution, enhancing durability, and making the production process more cost-efficient. This paper outlines potential interdisciplinary approaches, such as bioinspired materials and nanotechnology applications, to address these challenges and pave the way for next-generation hemodialysis membranes that are safer, more effective, and more accessible.

An Optimized Aerogel-Based Apheresis Device for Targeted Lipid Clearance in Elderly Hyperlipidemia Patients

Elderly patients with hyperlipidemia often exhibit resistance to conventional hypolipidemic treatments, underscoring the need for more effective strategies to address lipid imbalances in this high-risk group. This study introduces LipClean, an aerogel-based apheresis device specifically designed to remove harmful plasma lipids. LipClean is constructed using hydrophilic cellulose fibers, which serve as a supramolecular platform for synthesizing hydrophobic conjugated polymers through a Sonogashira-Hagihara reaction. These conjugated polymers are then cross-linked with the cellulose fibers via phosphorylation, generating an aerogel monolith with an interpenetrating network of hydrophilic fibers and hydrophobic polymers. Unlike bilayer aerogels that separate hydrophilic and hydrophobic layers, LipClean's interpenetrating structure is precisely engineered through polymer design and gradient cross-linking. This optimization enhances both bodily fluid flow and lipid adsorption while minimizing the removal of essential plasma components and ensuring unobstructed cell passage. In preclinical testing, LipClean significantly reduced triglyceride and cholesterol levels in an elderly rat model of hyperlipidemia and normalized lipid levels in blood samples from hypertensive patients. Importantly, purified blood maintained normal levels of blood cells and physiological and biochemical indicators after apheresis, highlighting LipClean's potential for managing hyperlipidemia-related disorders. This study, therefore, underscores the importance of interdisciplinary collaboration in driving medical device innovation.

Sulfonated covalent organic frameworks (COF)/polyethersulfone (PES) membrane with enhanced hemocompatibility for blood oxygenation

In extracorporeal membrane oxygenation (ECMO) treatment, designing membrane with self-anticoagulant properties can solve problems resulting from the adverse effect of anticoagulants. In this study, 2,4,6-Triformylphloroglucinol (Tp) and 2,5-Diaminobenzenesulfonic acid (Pa-SO3H) were applied to grow a sulfonated COF film in situ on the polyethersulfone (PES) membrane. The introduction of sulfonic groups increased the hydrophilicity and electronegativity of the TpPa COF film, improved its anti-protein adhesion properties, maintained the normal morphology of blood cells, and endowed the COF film with antithrombotic properties. In the porcine blood circulation test, the duration to increase So2 (O2 saturation) from ∼75-95 % in TpPa-SO3H COF/PES membrane (M-TpPa-SO3H) was 70 min shorter than that in TpPa COF/PES membrane (M-TpPa). This preparation method is applicable to the preparation of not only flat membranes, but also hollow fiber membranes. These findings emphasize the potential of M-TpPa-SO3H in ECMO applications, providing superior antithrombotic property and CO2 efflux potential.

Simulation-based assessment of zwitterionic pendant group variations on the hemocompatibility of polyethersulfone membranes

In the realm of hemodialysis, Polyethersulfone (PES) membranes dominate due to their exceptional stability and mechanical properties, capturing 93% of the market. Despite their widespread usage, the hydrophobic nature of PES introduces complications in hemodialysis, potentially leading to severe adverse reactions in patients with end-stage renal disease (ESRD) through protein fouling. Addressing this issue, our study focused on enhancing hemocompatibility by modifying PES surfaces with zwitterionic materials, known for their hydrophilicity and biological membrane compatibility. We investigated the functionalization of PES membranes utilizing various zwitterions in different ratios. Utilizing molecular docking, we examined the interactions of three zwitterionic ligands-carboxybetaine methacrylate (CBMA), sulfobetaine methacrylate (SBMA), and (2-(methacryloyloxy)ethyl) phosphorylcholine (MPC)-with human serum proteins. Our analysis revealed that a 1:1 ratio of phosphobetaine and sulfobetaine exhibits the lowest affinity energy towards serum proteins, denoting an optimal hemocompatibility without the limitations associated with increased zwitterion ratios. This pivotal finding offers a new pathway for developing more efficient and safer hemodialysis membranes, promising improved care for ESRD patients.

Supplementary information

The online version contains supplementary material available at 10.1186/s42252-024-00062-6.

Incorporating Anticoagulant and Antiplatelet Dual Functional Groups into Thermosetting Polymer Chain for Enhancing Antithrombogenicity

In clinical practice, high-effective antithrombosis remains a challenge for blood-contacting medical devices. Inspired by the enhanced antithrombogenicity of anticoagulant and antiplatelet combination therapy, a strategy is proposed to synthesize dual-pathway antithrombotic polymers by incorporating anticoagulant and antiplatelet dual functional groups into a single thermosetting polymer chain. The synthesized polymer shows increased antithrombogenicity in vitro, with prolonged activated partial thromboplastin time (APTT) and decreased platelet adhesion. Additionally, it downregulates the expression of coagulation- and inflammation-related factors in rabbit plasma after ex vivo arteriovenous shunt assay and maintains patency of small vascular grafts for at least 6 months without thrombosis on the luminal surface after in vivo replacement of rabbit carotid artery. This work provides a new approach to producing novel antithrombotic polymers for blood-contacting medical devices.

Anticoagulation polyvinyl chloride extracorporeal circulation catheters for heparin-free treatment

Extracorporeal circulation (ECC) catheters have potential to be blood compatible and could be used to prevent thrombotic occlusion. Here, we produced heparin-mimicking anticoagulation PVC tubing on a large scale by synthesizing a heparin-mimicking polymer (HMP) and co-extruding. The PVC@HMP catheter was evaluated using whole human blood in vitro, which indicated it could prevent plasma protein attachment, reduce platelet adhesion and activation, and inhibit coagulation factors (XII, XI, IX, and VIII). Moreover, the anticoagulation PVC tubing was assembled into extracorporeal circulation with a New Zealand rabbit model, manifesting excellent real-time antithrombogenic properties without systemic heparin anticoagulation in vivo. The rapid recovery of coagulation factors after operation further confirmed its superiority over heparin, which would not completely inactivate the activity of those coagulation factors (XII, XI, IX and VIII). In addition, the PVC@HMP-1 catheters remain patent after being implanted in rats for 28 days without apparent inflammation and mortality complications. The anticoagulation PVC tubes could be used to construct various systemic and integrative anticlotting biomedical devices, which would dramatically reduce the introduction of heparin into blood circulation, thus preventing side effects and promoting the development of heparin-free treatment.

Fabrication of a Dual-Action Membrane with Both Antibacterial and Anticoagulant Properties via Cationic Polyelectrolyte-Induced Phase Separation

The development of microorganisms and formation of thrombus on a biomaterial surface can seriously lead to device failure and threaten human health. Nonetheless, a surface that has both antibacterial and anticoagulant properties has scarcely been developed. Herein, a novel dual-action membrane composed of polyethersulfone (PES) bulk material and a hydrophilic anionic poly-2-acrylamido-2-methylpropanesulfonic acid (PAMPS) polymer has been prepared via the cationic antibacterial agent poly(hexamethylene biguanide) (PHMB)-induced phase separation technique. Interestingly, the resultant membrane can offer tunable antibacterial and anticoagulant properties, while maintaining satisfactory permeability and greatly increasing selectivity. The membrane also shows excellent hydrophilicity, a well-defined porous surface, and cross section with a sponge gradient structure. Furthermore, the PHMB-PAMPS complex formed on the membrane surface displays outstanding long-term stability, which is crucial for further practical applications. More importantly, the hollow fiber membrane fabricated by the cationic polyelectrolyte-induced phase separation technique confirms its capability to control the membrane permeability (257.4 L·m^-2·h^-1·bar^-1) and selectivity (95.9%) without destroying the membrane structure. The present work opens a straightforward and efficient avenue for the rational design of a functional surface to fight biomedical material-associated infections.

Case studies of clinical hemodialysis membranes: influences of membrane morphology and biocompatibility on uremic blood-membrane interactions and inflammatory biomarkers

End stage renal disease (ESRD) patients depend on hemodialysis (HD) as a life-sustaining treatment, but HD membrane properties play a critical role in blood activation during HD and can lead to severe patient outcomes. This study reports on a series of investigations on the common clinical HD membranes available in Canadian hospitals to explore the key reasons behind their susceptibility to blood activation and unstable cytokine. Clinical HD membranes composed of cellulose triacetate (CTA) and polyvinylpyrrolidone: polyarylethersulfone (PAES: PVP) were thoroughly characterized in terms of morphology and chemical composition. Membrane-surface interactions with uremic blood samples after HD treatment were probed using Fourier Transform Infra-Red (FTIR) and Raman spectroscopic techniques in order to understand changes in chemistry on membrane fibers. In addition, as part of this innovative study, we utilized Molecular Modeling Docking to examine the interactions of human blood proteins and membrane models to gain an in-depth understanding of functional group types responsible for perceived interactions. In-vitro adsorption of fibrinogen on different clinical HD membranes was compared at similar clinical operating conditions. Samples were collected from dialysis patients to ascertain the extent of inflammatory biomarkers released, before, during (30 and 90 min) and after dialysis (4 h). Collected blood samples were analyzed using Luminex assays for the inflammatory biomarkers of Serpin/Antithrombin-III, Properdin, C5a, 1L-1α, 1L-1β, TNF-α, IL6, and vWF. We have likewise incubated uremic blood in vitro with the two membrane materials to determine the impact that membrane materials pose in favor of activation away from the hydrodynamics influences. The results of our morphological, chemical, spectroscopic, and in vitro incubation analyses indicate that CTA membranes have a smoother surface and higher biocompatibility than PAES: PVP membranes, however, it has smaller pore size distribution, which results in poor clearance of a broad spectrum of uremic toxins. However, the rougher surface and greater hydrophilicity of PAES: PVP membranes increases red blood cell rupture at the membrane surface, which promotes protein adsorption and biochemical cascade reactions. Molecular docking studies indicate sulfone functional groups play an important role in the adsorption of proteins and receptors. PAES: PVP membranes result in slower but greater adsorption of fibrinogen, but are more likely to experience reversible and irreversible fouling as well as backfiltration. Our major finding is that a single dialysis session, even with a more biocompatible membrane such as CTA, increases the levels of complement and inflammation factors, but to a milder extent than dialysis with a PAES membrane.