In situ gel-forming oil as rectally delivering platform of hydrophobic therapeutics for ulcerative colitis therapy

Smart Silk-Based In Situ Sol-Gel Modulates Rectal Microenvironment for Effective Ulcerative Colitis Alleviation

Ulcerative colitis (UC) is a chronic inflammatory bowel disease, with untreated cases often progressing to colorectal cancer. Current treatments aim to induce inflammatory remission but often neglect the surrounding microenvironment, which significantly impairs mucosal healing and contributes to treatment failures. This study presents a novel silk fibroin-based fucoidan (SFU) in situ rectal gel, with sol-gel transition confirmed through rheological analysis under physiological pH and temperature conditions. The SFU gel exhibits strong antioxidant activity, achieving a DPPH radical scavenging rate of 73.3 ± 1.52%. The gel efficiently reduces reactive oxygen species (ROS) and nitric oxide (NO) production, demonstrating its reliable antioxidant effects. In a DSS-induced UC mouse model, SFU effectively alleviates colitis symptoms, including weight loss and disease activity index (DAI) reduction, with improved stool consistency and reduced rectal bleeding. Moreover, SFU therapy reprograms macrophages from proinflammatory M1 to anti-inflammatory M2 phenotypes, significantly lowering IL-6 and TNF-α levels, suggesting anti-inflammatory properties. Furthermore, SFU increased tight junction proteins Occludin-1 and ZO-1, indicating gut mucosal barrier integrity. SFU treatment restores goblet cells and mucin production while preventing fibrosis, demonstrating its potential as a natural therapy for UC treatment.

In situ gel-forming oil solubilizing α-lipoic acid as a physical shielding alleviated chemotherapy-induced oral mucositis via inhibiting oxidative stress

Oral mucositis (OM) is a common and serious complication of cancer chemoradiotherapy. OM managements mainly focused on topical healthcare or analgesia, which offers limited wound healing. Herein, in situ gel-forming oil (LGF) have been developed as a physical shielding for OM treatment. LGF oil, composed of soybean phosphatidyl choline (40 %, w/w), glycerol dioleate (54 %, w/w), and alcohols (6 %, w/w), is a viscous oil-like liquid. The contact angle of LGF oil on porcine buccal mucosa were 30°, significantly smaller than that of water (60°), indicating its good wetting and spreading properties. Besides, the adhesion force and adhesion energy of LGF oil toward porcine buccal mucosa was as high as 3.9 ± 0.2 N and 60 ± 2 J/m2, respectively, indicating its good adhesive property. Moreover, the hydrophobic α-lipoic acid (LA) as a native antioxidative agent was highly solubilized in LGF oil, its solubility in which was above 100 mg/mL. Upon contacting with saliva, LA-loaded LGF oil (LA-LGF) could rapidly transform from oil into gel that adheres on oral mucosa. Moreover, LA was slowly released from the formed LA-LGF gel, which benefited alleviating oxidative stress caused by chemoradiotherapy. In vivo animal experiments showed that LA-LGF could effectively promote the repairing of oral mucosa wound of 5-fluorouracil induced OM rats. Besides, the mucosa edema was greatly improved and new granulation around wound was produced after LA-LGF treatment. Meanwhile, the production of proinflammatory cytokines such as IL-1β, TNF-α, 1L-6 was substantially inhibited by LA-LGF. Collectively, LGF oil as carrier of hydrophobic drug might be a promising strategy for oral mucositis.

Effect of hydrogel drug delivery system for treating ulcerative colitis: A preclinical meta-analysis

Hydrogel drug delivery systems (DDSs) for treating ulcerative colitis (UC) have garnered attention. However, there is a lack of meta-analysis summarizing their effectiveness. Therefore, this study aimed to conduct a meta-analysis of pre-clinical evidence comparing hydrogel DDSs with free drug administration. Subgroup analyses were performed based on hydrogel materials (polysaccharide versus non-polysaccharide) and administration routes of the hydrogel DDSs (rectal versus oral). The outcome indicators included colon length, histological scores, tumor necrosis factor-α (TNF-α), zonula occludens protein 1(ZO-1), and area under the curve (AUC). The results confirmed the therapeutic enhancement of the hydrogel DDSs for UC compared with the free drug group. Notably, no significant differences were found between polysaccharide and non-polysaccharide materials, however, oral administration was found superior regarding TNF-α and AUC. In conclusion, oral hydrogel DDSs can serve as potential excellent dosage forms in oral colon -targeting DDSs, and in the design of colon hydrogel delivery systems, polysaccharides do not show advantages compared with other materials.

In-situ gel: A smart carrier for drug delivery

In-situ gel technology is a promising drug delivery strategy that undergoes a 'sol to gel' transition upon administration, providing controlled and prolonged drug release. These gels are composed of cross-linked 3D networks of polymers, with hydrogels being a specific type of absorbing water while retaining their shape. Gelation can be triggered by various stimuli, such as temperature, pH, ions, and light. They offer several advantages like improved patient compliance, extended drug residence time, localized drug delivery, etc, but also have some disadvantages like drug degradation and limited mechanical strength. In-situ gel falls into three categories: temperature-sensitive, ion-sensitive, and pH-sensitive, but multi-responsive gels that respond to multiple stimuli have better drug release characteristics. The mechanism of in-situ gel formation involves physical and chemical mechanisms. There are various applications of in-situ gel, like ocular drug delivery, nose-to-brain delivery, etc. In this review, we have discussed the types, and mechanisms of in-situ gel & use of in-situ gel in the treatment of different diseases through various routes like buccal, vaginal, ocular, nasal, etc., along with its use in targeted drug delivery.