Sulfonated, oxidized pectin-based double crosslinked bioprosthetic valve leaflets for synergistically enhancing hemocompatibility and cytocompatibility and reducing calcification.

Clinically frequently-used glutaraldehyde (GA)-crosslinked bioprosthetic valve leaflets (BVLs) are still curbed by acute thrombosis, malignant immunoreaction, calcification, and poor durability. In this study, an anticoagulant heparin-like biomacromolecule, sulfonated, oxidized pectin (SAP) with a dialdehyde structure was first obtained by modifying citrus pectin with sulfonation of 3-amino-1-propane sulfonic acid and then oxidating with periodate. Notably, a novel crosslinking approach was established by doubly crosslinking BVLs with SAP and the nature-derived crosslinking agent quercetin (Que), which play a synergistic role in both crosslinking and bioactivity. The double crosslinked BVLs also presented enhanced mechanical properties and enzymatic degradation resistance owing to the double crosslinking networks formed via CN bonds and hydrogen bonds, respectively, and good HUVEC-cytocompatibility. The in vitro and ex vivo assay manifested that the double-crosslinked BVLs had excellent anticoagulant and antithrombotic properties, owing to the introduction of SAP. The subcutaneous implantation also demonstrated that the obtained BVLs showed a reduced inflammatory response and great resistance to calcification, which is attributed to quercetin with multiple physiological activities and depletion of aldehyde groups by hydroxyl aldehyde reaction. With excellent stability, hemocompatibility, anti-inflammatory, anti-calcification, and pro-endothelialization properties, the obtained double-crosslinked BVLs, SAP + Que-PP, would have great potential to substitute the current clinical GA-crosslinked BVLs.

Well-designed two-fold crosslinked biological valve leaflets with heparin-loaded hydrogel coating for enhancing anticoagulation, endothelialization, and anticalcification.

Commercial biological valve leaflets (BVLs) crosslinked with glutaraldehyde (GA) are at risk of accelerating damage and even failure, owing to the high cell toxicity of GA, acute thrombosis, and calcification in clinical applications. In this study, a novel joint strategy of double crosslinking agents (dialdehyde pectin (AP) and carbodiimide) and heparin-loaded hydrogel coating was developed, endowing BVLs with excellent mechanical properties and multiple performances. Herein, AP played two essential roles, the crosslinking agent and the main component of the hydrogel coating. Both experimental and theoretical results indicated that the mechanical properties and stability of double-crosslinked BVLs were comparable to those of GA, and heparin loaded in hydrogel coating could improve the hemocompatibility of AP + EDC/NHS-PP. Further, cytocompatibility and in vivo tests showed that compared with GA-PP, AP + EDC/NHS + CS + Hep-PP has exhibited good endothelialization ability, mild immune response and anti-calcification performance and therefore prompts it to be an extremely valuable candidate for more durable and multifunctional BVLs.

Dialdehyde pectin-crosslinked and hirudin-loaded decellularized porcine pericardium with improved matrix stability, enhanced anti-calcification and anticoagulant for bioprosthetic heart valves.

To conveniently and effectively cure heart valve diseases or defects, combined with transcatheter valve technology, bioprosthetic heart valves (BHVs) originated from the decellularized porcine pericardium (D-PP) have been broadly used in clinics. Unfortunately, most clinically available BHVs crosslinked with glutaraldehyde (GA) were challenged in their long-term tolerance, degenerative structural changes, and even failure, owing to the synergistic impact of multitudinous elements (cytotoxicity, calcification, immune responses, etc.). In this work, dialdehyde pectin (AP) was prepared by oxidizing the o-dihydroxy of pectin with sodium periodate. Hereafter, the AP-fixed PP model was obtained by crosslinking D-PP with AP with high aldehyde content (6.85 mmol g-1), for acquiring excellent mechanical properties and outstanding biocompatibility. To further improve the hemocompatibility of the AP-fixed PP, a natural and specific inhibitor of thrombin (hirudin) was introduced to achieve surface modification of the AP-fixed PP. The feasibility of crosslinking and functionalizing AP-fixed PP, which was a potential leaflet material of BHVs, was exhaustively and systematically evaluated. In vitro studies found that hirudin-loaded and AP-fixed PP (AP + Hirudin-PP) had synchronously achieved effective fixation of collagen, highly effective anticoagulation, and good HUVECs-cytocompatibility. In vivo results revealed that the AP + Hirudin-PP specimens recruited the minimum immune cells in the implantation experiment, and also presented an excellent anti-calcification effect. Overall, AP + Hirudin-PP was endowed with competitive collagen stability (compared with GA-fixed PP), excellent hemocompatibility, good HUVECs-cytocompatibility, low immunogenicity and outstanding anti-calcification, suggesting that AP + Hirudin-PP might be a promising alternative to GA-fixed PP and exhibited a bright prospect in the clinical applications of BHVs.

Combined Contribution of Increased Intestinal Permeability and Inhibited Deglycosylation of Ginsenoside Rb1 in the Intestinal Tract to the Enhancement of Ginsenoside Rb1 Exposure in Diabetic Rats after Oral Administration.

Panax ginseng is becoming a promising antidiabetic herbal medication. As the main active constituents of Panax ginseng, ginsenosides are well known, poorly absorbed chemicals. However, the pharmacokinetic behavior of ginsenosides under diabetic conditions is not fully understood. This study aimed to explore the alterations and potential mechanisms of pharmacokinetic behavior of ginsenoside Rb1 in diabetic rats compared with normal rats and rats fed a high-fat diet. Systemic exposure (area under the concentration-time curve extrapolated from zero to infinity) was significantly increased in diabetic rats after oral administration of Rb1. Oral bioavailability of Rb1 was significantly higher in diabetic rats (2.25%) compared with normal rats (0.90%) and rats fed a high-fat diet (0.78%). Further studies revealed that increased Rb1 exposure in diabetic rats may be mainly attributed to increased Rb1 absorption via the intestine and inhibited Rb1 deglycosylation by the intestinal microflora. Neither metabolic enzymes nor drug transporters displayed appreciable effects on Rb1 disposition. The transport of paracellular markers (fluorescein sodium and fluorescein isothiocyanate-dextran of 4 kDa) as well as Rb1 itself across the Caco-2 monolayer cultured with diabetic serum was promoted, demonstrating that increased paracellular permeability of the Caco-2 monolayer may benefit intestinal Rb1 absorption. In addition, Rb1 exposure was decreased in diabetic rats after Rb1 intravenous administration, which may result from increased Rb1 urinary excretion. In conclusion, Rb1 oral exposure was significantly increased under diabetic conditions, which is of positive significance to clinical treatment. The potential mechanism may be associated with the combined contribution of increased gut permeability and inhibited deglycosylation of ginsenoside Rb1 by intestinal microflora.