Crosslinking of dialdehyde heparin: a new strategy for improving the anticoagulant properties of porcine acellular dermal matrix

A New Type of Bioprosthetic Heart Valve: Synergistic Modification with Anticoagulant Polysaccharides and Anti-inflammatory Drugs

Valvular heart disease (VHD) poses a significant threat to human health, and the transcatheter heart valve replacement (THVR) is the best treatment for severe VHD. Currently, the glutaraldehyde cross-linked commercial bioprosthetic heart valves (BHVs) remain the first choice for THVR. However, the cross-linking by glutaraldehyde exhibits several drawbacks, including calcification, inflammatory reactions, and difficult endothelialization, which limits the longevity and applicability of BHVs. In this study, λ-carrageenan with anticoagulant function was modified by carboxymethylation into carboxymethyl λ-carrageenan (CM-λC); subsequently, CM-λC was used as a cross-linking agent to stabilize decellularized bovine pericardial tissue through amide bonds formed by a 1-(3-(Dimethylamino)propyl)-3-ethylcarbodiimide/N-Hydroxysuccinimide (EDC/NHS)-catalyzed reaction between the amino functional groups within pericardium and the carboxyl group located on CM-λC. Lastly, the inclusion complex (CD/Rutin) (formed by encapsulating the rutin molecule through the hydrophobic cavity of the mono-(6-ethylenediamine-6-deoxy)-β-cyclodextrin) was immobilized onto above BHVs materials (λCar-BP) through the amidation reaction. The treated sample exhibited mechanical properties and collagen stability similar to those of GA-BP, except for improved flexibility. Because of the presence of sulfonic acid groups and absence of aldehyde group as well as the Rutin release from CD/Rutin immobilized onto BHVs, the hemocompatibility, anti-inflammatory, HUVEC-cytocompatibility, and anticalcification properties, of the CM-λC-fixed BP modified with CD/Rutin was significantly better than that of GA-BP. In summary, this nonaldehyde-based natural polysaccharide cross-linking strategy utilizing the combination of CM-λC and CD/Rutin provides a novel solution to obtain BHVs with durable and stable anticoagulant, anticalcification, and anti-inflammatory properties, and has a wide range of potential applications in improving the various properties of BHVs.

Acellular dermal matrix in urethral reconstruction

The management of severe urethral stricture has always posed a formidable challenge. Traditional approaches such as skin flaps, mucosal grafts, and urethroplasty may not be suitable for lengthy and intricate strictures. In the past two decades, tissue engineering solutions utilizing acellular dermal matrix have emerged as potential alternatives. Acellular dermal matrix (ADM) is a non-immunogenic biological collagen scaffold that has demonstrated its ability to induce layer-by-layer tissue regeneration. The application of ADM in urethral reconstruction through tissue engineering has become a practical endeavor. This article provides an overview of the preparation, characteristics, advantages, and disadvantages of ADM along with its utilization in urethral reconstruction via tissue engineering.

Utilizing epoxy Bletilla striata polysaccharide collagen sponge for hemostatic care and wound healing

Hemostatic materials that are lightweight and possess good blood absorption performance have been widely considered for use in modern wound care. Natural hemostatic ingredients derived from traditional Chinese medicine have also received extensive attention. Bletilla polysaccharides are valued by researchers for their excellent hemostatic performance and good reactivity. Collagen is favored by researchers due to its high biocompatibility and low immunogenicity. In this study, Bletilla striata polysaccharide, the main hemostatic component of Bletilla striata, was activated by epoxy groups, and epoxidized Bletilla striata polysaccharide (EBSP) was prepared. Then, EBSP was crosslinked with collagen under alkaline conditions, and a new hemostatic material that was an epoxidized Bletilla polysaccharide crosslinked collagen hemostatic sponge was prepared. We demonstrated that endowing collagen with better hemostatic performance, cytocompatibility, and blood compatibility does not destroy its original three-stranded helical structure. Compared with the medical gauze, hemostasis time was shorter (26.75 ± 2.38 s), and blood loss was lower (0.088 ± 0.051 g) in the rat liver injury hemostasis model. In the rat model of severed tail hemostasis, hemostasis time was also shorter (47.33 ± 2.05 s), and the amount of blood loss was lower (0.330 ± 0.122 g). The sponge possessed good hemostatic and healing performance.

A multifunctional bio-patch crosslinked with glutaraldehyde for enhanced mechanical performance, anti-coagulation properties, and anti-calcification properties

Bio-patches for the treatment of valvular disease have been evaluated in clinical trials. It has been shown that failure of these devices, occurring within a few years of implantation, may be due to cytotoxicity, immune response, calcification and thrombosis. Some of these effects may be due to the glutaraldehyde crosslinking process used in the preparation of the materials. A number of studies have focused on strategies to control calcification, while others have concentrated on the prevention of micro-thrombus formation. In the present work, we have introduced amino-terminated poly(ethylene glycol) (NH2-PEG-NH2) as an intermolecular bridge, which not only eliminates free aldehyde groups to prevent calcification, but also introduces sites for the attachment of anticoagulant molecules. Furthermore, PEG, itself a hydrophilic polymer with good biocompatibility, may effectively prevent protein adsorption in the early stages of blood contact leading to thrombus formation. After further covalent attachment of heparin, modified bovine pericardium (BP) showed strong anti-calcification (calcium content: 39.3 ± 3.1 μg mg-1) and anti-coagulation properties (partial thromboplastin time: >300 s). The biocompatibility and mechanical properties, important for clinical use, were also improved by modification. The strategy used in this work includes new ideas and technologies for the improvement of valve products used in the clinic.

Converting Acellular Dermal Matrix into On-Demand Versatile Skin Scaffolds by a Balanceable Crosslinking Approach for Integrated Infected Wounds Therapy

Ideal tissue-engineered skin scaffolds should possess integrated therapeutic effects and multifunctionality, such as broad-spectrum antibacterial properties, adjustable mechanical properties, and bionic structure. Acellular dermal matrix (ADM) has been broadly used in many surgical applications as an alternative treatment to the "gold standard" tissue transplantation. However, insufficient broad-spectrum antibacterial and mechanical properties for therapeutic efficacy limit the practical clinical applications of ADM. Herein, a balanceable crosslinking approach based on oxidized 2-hydroxypropyltrimethyl ammonium chloride chitosan (OHTCC) was developed for converting ADM into on-demand versatile skin scaffolds for integrated infected wounds therapy. Comprehensive experiments show that different oxidation degrees of OHTCC have significative influences on the specific origins of OHTCC-crosslinked ADM scaffolds (OHTCC-ADM). OHTCC with an oxidation degree of about 13% could prosperously balance the physiochemical properties, antibacterial functionality, and cytocompatibility of the OHTCC-ADM scaffolds. Owing to the natural features and comprehensive crosslinking effects, the proposed OHTCC-ADM scaffolds possessed the desirable multifunctional properties, including adjustable mechanical, degradable characteristics, and thermal stability. In vitro/in vivo biostudies indicated that OHTCC-ADM scaffolds own well-pleasing broad-spectrum antibacterial performances and play effectively therapeutic roles in treating infection, inhibiting inflammation, promoting angiogenesis, and promoting collagen deposition to enhance the infected wound healing. This study proposes a facile balanceable crosslinking approach for the design of ADM-based versatile skin scaffolds for integrated infected wounds therapy.

Origin of critical nature and stability enhancement in collagen matrix based biomaterials: Comprehensive modification technologies

Collagen is the most abundant protein in animals and one of the most important extracellular matrices that chronically plays an important role in biomaterials. However, the major concern about native collagen is the lack of its thermal stability and weak resistance to proteolytic degradation. Currently, a series of modification technologies have been explored for critical nature and stability enhancement in collagen matrix-based biomaterials, and prosperously large-scale progress has been achieved. The establishment of covalent bonds among collagen noumenon has been verified assuringly to have pregnant influences on its physicochemical properties and biological properties, enlightening to discuss the disparate modification technologies on specific effects on the multihierarchical structures and pivotal performances of collagen. In this review, various existing modification methods were classified from a new perspective, scilicet whether to introduce exogenous substances, to reveal the basic scientific theories of collagen modification. Understanding the role of modification technologies in the enhancement of collagen performance is crucial for developing novel collagen-based biomaterials. Moreover, the different modification effects caused by the interaction sites between the modifier and collagen, and the structure-activity relationship between the structure of the modifier and the properties of collagen were reviewed.

Heparinized Collagen Scaffolds Based on Schiff Base Bonds for Wound Dressings Accelerate Wound Healing without Scar

Skin wound healing is a complex process with multiple growth factors and cytokines participating and regulating each other. It is essential to develop novel wound dressings to accelerate the wound healing process. In this study, we developed the heparinized collagen scaffold materials (OL-pA), and the cross-linking reaction was based on the Schiff base reaction between pig acellular dermal matrix (pADM) and dialdehyde low molecular weight heparin (LMWH). Compared with pADM, the OL-pA modified by cross-linking still retained the triple helix structure of native collagen. When the dosage of the OL cross-linking agent was 12 wt %, the cross-linking density of OL-pA was 49.67%, the shrinkage temperature was 75.6 °C, the tensile strength was 14.62 MPa, the elongation at break was 53.14%, and the water contact angle was 25.1°, all of which were significantly improved compared with pADM. The cytocompatibility test showed that L929 cells adhered better on the surface of OL-pA scaffolds, and the proliferation ability of primary fibroblasts was enhanced. In vivo experiments showed that the OL-pA scaffolds could better accelerate wound healing, more effectively promote the positive expression of bFGF, PDGF, and VEGF growth factors, accelerate capillary angiogenesis, and promote wound scarless healing. In summary, the OL-pA scaffolds have more excellent hygrothermal stability, mechanical properties, hydrophilicity, and cytocompatibility. Especially the scaffolds have significant pro-healing properties for the full-thickness skin wound of rats and are expected to be a potential pro-healing collagen-based wound dressing.