Balancing Microthrombosis and Inflammation via Injectable Protein Hydrogel for Inflammatory Bowel Disease

Abstract

Emerging evidence indicates that a vicious cycle between inflammation and microthrombosis catalyzes the pathogenesis of inflammatory bowel disease (IBD). Over-stimulated inflammation triggers a coagulation cascade and leads to microthrombosis, which further complicates the injury through tissue hypoxia and ischemia. Herein, an injectable protein hydrogel with anti-thrombosis and anti-inflammation competency is developed to impede this cycle, cross-linked by silver ion mediated metal-ligand coordination and electronic interaction with sulfhydryl functionalized bovine serum albumin and heparin, respectively. The ex vivo experiments show that the hydrogel, HEP-Ag-BSA, exhibits excellent self-healing ability, injectability, biocompatibility, and sustained drug release. HEP-Ag-BSA also demonstrates anti-coagulation and anti-inflammation abilities via coagulation analysis and lipopolysaccharide stimulation assay. The in vivo imaging confirms the longer retention time of HEP-Ag-BSA at inflammatory sites than in normal mucosa owing to electrostatic interactions. The in vivo study applying a mouse model with colitis also reveals that HEP-Ag-BSA can robustly inhibit inflammatory microthrombosis with reduced bleeding risk. This versatile protein hydrogel platform can definitively hinder the "inflammation and microthrombosis" cycle, providing a novel integrated approach against IBD.

Amyloid‐Based Albumin Hydrogels

“…[11,56] Previous albumin-based hydrogels were chemically modified to introduce reactive groups on the protein for its subsequent cross-linking into 3D networks. [7][8][9]11] While such approaches result in more robust hydrogels due to covalent bond formation, they are associated with extra reaction and purification steps, concerns of side effects and extra costs. Amyloid-like fibril formation of non-modified albumin was previously considered, but usually entailed a heating step that most likely causes protein degradation, as shown for similar proteins undergoing amyloidogenesis.…”

“…Hence unsurprisingly, it has been previously considered by many as the building block for creating albumin-based hydrogels. [6][7][8][9][10][11] In most cases however, the use of chemical reagents to either chemically modify the albumin, or induce cross-linking of side chains, introduces concerns related to cytotoxicity, reproducibility, and undesired side products. An alternative approach that we explored in this study, is to denature albumin and drive its assembly into amyloid-like fibrils, which would then physically interact to create a free-standing hydrogel material.…”

Pathophysiological mechanisms of thrombosis in acute and long COVID-19

“…Heparin, including unfractionated heparin and low-molecular-weight heparin (LMWH), can bind to antithrombin (AT), and enhance inhibitory effects of AT on FXa and thrombin ( 177 , 178 ). Accumulating evidence suggests that heparin can regulate the inflammatory response in multiple ways, including inhibition of both selectin-induced neutrophil adhesion and the release of inflammatory mediators ( 179 , 180 ). Recent studies address the relationship between heparin and SARS-CoV-2, considering whether heparin directly binds to the S protein of SARS-CoV-2, and exerts direct antiviral effects ( 181 ).…”

Targeting pathophysiological changes using biomaterials-based drug delivery systems: A key to managing inflammatory bowel disease

“…If there is a physical barrier that prevents the adhesion of some intestinal pathogens Frontiers in Pharmacology frontiersin.org such as Clostridium difficile to inflamed colon epithelium, it can be a prophylaxis strategy for inflamed colon infection. Hydrogelbased enema as one of the most attractive biomaterials-based DDSs for local drug delivery can fulfill this aim because it adheres to the inflamed colon epithelium and forms a physical barrier (Hong et al, 2022). Hence, developing these enemas can help in the prophylaxis of inflamed colon infection.…”

“…The hydrogel-based enema showed excellent accumulation in the injured colon compared with the healthy tissues as well as was effective in downregulation of interleukin-6 (a pro-inflammatory agent) in the colon’s inflamed regions, indicating the good functionality of this hydrogel for local targeting the damaged areas of the colon. Moreover, this enema exhibited the ability of accelerating mucosal healing via boosting Syndecan-1 (Sdc-1), a tissue repair agent, and can also help in the prophylaxis of inflamed colon infection via physical barrier formation ( Hong et al, 2022 ). In a similar study, the treatment of colitic mice with enema based on negatively charged hydrogel microfibers loaded with dexamethasone showed preferential adhesion of these hydrogel microfibers to the inflamed regions of the colon compared to histologically normal tissues.…”