Construction of a Homologous Targeting Exosome-Based Drug Delivery System for Colorectal Cancer and Evaluation of Its Anti-Tumor Efficacy

Objective: This study aimed to use the homologous targeting property of tumor-derived exosomes to construct a novel drug delivery system for SN38 and assess its enhanced therapeutic potential in colorectal cancer models. Methods: Exosomes were isolated from HT29 colorectal cancer cells (HT29-EXO) and NCM460 normal intestinal epithelial cells (NCM460-EXO) using differential ultracentrifugation, followed by characterization via nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and Western blotting (WB). The chemotherapeutic drug SN38 was subsequently loaded into the exosomes via electroporation. The homologous targeting capability of HT29-EXO was validated through both in vitro cell co-culture studies and in vivo live imaging. Finally, the antitumor efficacy of the drug-loaded exosomes (HT29-EXO+SN38) was systematically evaluated using CCK-8 cell viability assays, flow cytometry-based apoptosis analysis, and a subcutaneous xenograft mouse model. Results: This study conclusively demonstrates the superior homologous targeting of HT29-derived exosomes, showing 1.5-fold higher in vitro binding affinity and 2-fold greater in vivo tumor accumulation compared to control exosomes (NCM460-EXO). The therapeutic formulation HT29-EXO+SN38 proved significantly more effective. In vitro, it exhibited the strongest growth inhibition, reducing cell viability to 35.79%. Flow cytometry revealed that while total apoptosis rates were comparable, HT29-EXO+SN38 induced the highest rate of late apoptosis (41.57%, p <0.001 vs. others). These results were corroborated in vivo, where the HT29-EXO+SN38 group showed the most potent efficacy, achieving the lowest final tumor weight (182.0 ± 36.33 mg) and smallest volume (103.1 ± 36.8 mm³), with significant differences versus all other groups ( p <0.05). Conclusion: Utilizing homologous tumor-derived exosomes as drug carriers enhances tumor inhibition by their superior targeting of parental cells and tissues.