Ultrasound-responsive microbubbles for sonography-guided siRNA delivery

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Cancer Therapeutics

Background:

• RNA interference (RNAi) holds promise for cancer gene therapy.
• Nanocarrier-based delivery of small interfering RNA (siRNA) often shows insufficient tumor targeting due to limitations of the enhanced permeability and retention (EPR) effect.

Purpose of the Study:

• To develop an ultrasound-responsive microbubble (MB) system for enhanced tumor-targeted delivery of siRNA.
• To evaluate the therapeutic efficacy and theranostic potential of siRNA-loaded MBs in a preclinical cancer model.

Main Methods:

• siRNA-loaded, ultrasound-responsive MBs were fabricated using a hetero-assembling strategy with polymeric siRNA micelles and liposomal MBs.
• Intratumoral injection of XIAP siRNA/MBs followed by low-frequency ultrasound exposure was administered to a human cervical cancer xenograft model in nude mice.
• Gene silencing, apoptosis markers, and tumor growth were assessed. Ultrasound imaging was used for real-time monitoring.

Main Results:

• Ultrasound exposure significantly enhanced siRNA delivery into deep tumor regions by increasing permeability.
• Improved XIAP gene silencing and cleaved caspase-3 activation were observed, leading to significant therapeutic effects.
• The siRNA/MBs functioned as an effective contrast agent for real-time ultrasound monitoring of the tumor.

Conclusions:

• Multi-functional siRNA/MBs represent a promising theranostic platform for cancer gene therapy.
• This approach overcomes limitations of traditional nanocarrier delivery by utilizing ultrasound for enhanced targeting and therapeutic delivery.
• The system offers potential for combined gene therapy and real-time tumor monitoring.