Recent advances in photoacoustic endoscopy

Imaging based on photoacoustic effect relies on illuminating with short light pulses absorbed by tissue absorbers, resulting in thermoelastic expansion, giving rise to ultrasonic waves. The ultrasonic waves are then detected by detectors placed around the sample. Photoacoustic endoscopy(PAE) is one of four major implementations of photoacoustic tomography that have been developed recently. The prototype PAE was based on scanning mirror system that deflected both the light and the ultrasound. A recently developed mini-probe was further miniaturized, and enabled simultaneous photoacoustic and ultrasound imaging. This PAE-endoscopic ultrasound(EUS) system can offer high-resolution vasculature information in the gastrointestinal(GI) tract and display differences between optical and mechanical contrast compared with single-mode EUS. However, PAE for endoscopic GI imaging is still at the preclinical stage. In this commentary, we describe the technological improvements in PAE for possible clinical application in endoscopic GI imaging. In addition, we discuss thetechnical details of the ultrasonic transducer incorporated into the photoacoustic endoscopic probe.

Recent advances in targeted endoscopic imaging:Early detection of gastrointestinal neoplasms

Molecular imaging has emerged as a new discipline in gastrointestinal endoscopy.This technology encompasses modalities that can visualize disease-specific morphological or functional tissue changes based on the molecular signature of individual cells.Molecular imaging has several advantages including minimal damage to tissues,repetitive visualization,and utility for conducting quantitative analyses.Advancements in basic science coupled with endoscopy have made early detection of gastrointestinal cancer possible.Molecular imaging during gastrointestinal endoscopy requires thedevelopment of safe biomarkers and exogenous probes to detect molecular changes in cells with high specificity anda high signal-to-background ratio.Additionally,a high-resolution endoscope with an accurate wide-field viewing capability must be developed.Targeted endoscopic imaging is expected to improve early diagnosis and individual therapy of gastrointestinal cancer.

Gene editing particle system as a therapeutic approach for drug-resistant colorectal cancer

The epidermal growth factor receptor(EGFR)pathway plays an important role in the progression of colorectal cancer(CRC).Anti-EGFR drugs based on antibodies have been widely used for treating CRC through inducing the cell death pathway.However,the majority of CRC patients will inevitably develop drug-resistance during anti-EGFR drug treatment,which is mainly caused by a point mutation in the KRAS oncogene.We developed a nanoliposomal(NL)particle containing the Cas9 protein and a single-guide RNA(sgRNA)complex(Cas9-RNP),for genomic editing of the KRAS mutation.The NL particle is composed of bio-compatible lipid compounds that can effectively encapsulate Cas9-RNP.By modifying the NL particle to include the appropriate antibody,it can specifically recognize EGFR expressing CRC and effectively deliver the gene-editing complexes.The conditions of NL treatment were optimized using a KRAS mutated CRC in vivo mouse model.Mice with KRAS-mutated CRC showed drug resistance against cetuximab,a therapeutic antibody drug.After treating the mice with the KRAS gene-editing NL particles,the implanted tumors showed a dramatic decrease in size.Our results demonstrated that this genomic editing complex has great potential as a therapeutic carrier system for the treatment of drug-resistant cancer caused by a point mutation.