Phosphatidylserine-functionalized liposomes-in-microgels for delivering genistein to effectively treat ulcerative colitis

Ulcerative colitis (UC) is an inflammatory disease involving ulcers in the colon and rectum. The conventional treatments for UC still have many limitations, such as non-specific release, adverse effects and low absorption, resulting in the poor bioavailability of therapeutic agents. To address these challenges, targeting delivery systems are required to specifically deliver drugs to the colonic site with controlled release. Herein, we present a novel microgel oral delivery system, loaded with liposome nanoparticles (Li NPs) containing a natural anti-inflammatory compound genistein (Gen) into alginate microgels, thereby achieving the targeted release of Gen in the colonic region and ameliorating UC symptoms. Initially, Gen was loaded into phosphatidylserine (PS)-functionalized Li NPs to form Gen@Li NPs with an average size of 245.9 ± 9.6 nm. In vitro assessments confirmed that Gen@Li NPs efficiently targeted macrophages and facilitated the internalization of Gen into cells. To prevent rapid degradation in the harsh gastrointestinal tract, Gen@Li NPs were further encapsulated into alginate microgels through electric spraying technology, forming Gen@Li microgels. In vivo distribution tests demonstrated that Gen@Li microgels possessed long-term retention in the colon and gradual release characteristics compared to Gen@Li NPs. Furthermore, in vivo experiments confirmed that Gen@Li microgels significantly alleviated UC symptoms in mice induced by dextran sulfate sodium salt (DSS) mainly through reducing the expression levels of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and promoting colonic mucosal barrier repair through upregulation of mucosal protein expression. This study shed light on the potential of utilizing oral administration of natural compounds for UC treatment.