Enhancing Pancreatic Cancer Therapy with Targeted CD133-Exosome Delivery of PD-L1 siRNA: A Preclinical Investigation.

Objectives: This study assessed the anticancer potential of genetically modified exosomes engineered to express CD133-binding peptides on their surface and carry PD-L1 siRNA for the treatment of murine model of metastatic pancreatic cancer.

Methods: CD133-targeting exosomes (tEx) were generated by harvesting conditioned media from adipose-derived stem cells (ASCs) that had undergone transformation using pDisplay vectors encoding CD133-binding peptide sequences. Subsequently, siPD-L1-loaded CD133-targeting Exosomes, referred to as tEx(s), were created by incorporating PD-L1 siRNA into the tEx using Exofect kit.

Results: tEx(s) demonstrated superior targetability compared to other materials, including Ex, Ex(p), and tEx. This was substantiated by higher Total Radiant Efficiency (TRE) observed in metastatic liver and pancreatic tissues following intravenous administration of tEx(s) ( P < 0.05). Furthermore, the intravenous delivery of tEx(s) resulted in the most pronounced upregulation of pro-apoptotic markers (BIM and c-caspase 3) and the least downregulation of the anti-apoptotic markers (Mcl-1 and Bcl-xL) which has been demonstrated in various methods, including RT-PCR, Western blot analysis, and immunohistochemistry in the metastatic lesions in the livers ( P < 0.05).

Conclusions: PD-L1 siRNA-loaded CD133-targeting exosomes demonstrated remarkable anticancer efficacy, characterized by specific binding to CD133-positive pancreatic cancer cells and suppression of PD-L1 expression within these cells.