Directed evolution of the fluorescent protein CGP with in situ biosynthesized noncanonical amino acids.

The incorporation of noncanonical amino acids (ncAAs) into proteins can enhance their function beyond the abilities of canonical amino acids and even generate new functions. However, the ncAAs used for such research are usually chemically synthesized, which is expensive and hinders their application on large industrial scales. We believe that the biosynthesis of ncAAs using metabolic engineering and their employment in situ in target protein engineering with genetic code expansion could overcome these limitations. As a proof of principle, we biosynthesized four ncAAs, O-L-methyltyrosine, 3,4-dihydroxy-L-phenylalanine, 5-hydroxytryptophan, and 5-chloro-L-tryptophan using metabolic engineering and directly evolved the fluorescent consensus green protein (CGP) by combination with nine other exogenous ncAAs in Escherichia coli. After screening a TAG scanning library expressing 13 ncAAs, several variants with enhanced fluorescence and stability were identified. The variants CGPV3pMeoF/K190pMeoF and CGPG20pMeoF/K190pMeoF expressed with biosynthetic O-L-methyltyrosine showed an approximately 1.4-fold improvement in fluorescence compared to the original level, and a 2.5-fold improvement in residual fluorescence after heat treatment. Our results demonstrated the feasibility of integrating metabolic engineering, genetic code expansion, and directed evolution in engineered cells to employ biosynthetic ncAAs in protein engineering. These results could further promote the application of ncAAs in protein engineering and enzyme evolution. IMPORTANCE: Noncanonical amino acids (ncAAs) have shown great potential in protein engineering and enzyme evolution through genetic code expansion. However, in most cases, ncAAs must be provided exogenously during protein expression, which hinders their application, especially when they are expensive or have poor cell membrane penetration. Engineering cells with artificial metabolic pathways to biosynthesize ncAAs and employing them in situ for protein engineering and enzyme evolution could facilitate their application and reduce costs. Here, we attempted to evolve the fluorescent consensus green protein (CGP) with biosynthesized ncAAs. Our results demonstrated the feasibility of using biosynthesized ncAAs in protein engineering, which could further stimulate the application of ncAAs in bioengineering and biomedicine.

Individually tailored spatial-spectral pulsed CEST MRI for ratiometric mapping of myocardial energetic species at 3T.

PURPOSE: CEST MRI has been used to probe changes in cardiac metabolism via assessment of CEST contrast from Cr. However, B1 variation across the myocardium leads to spatially variable Cr CEST contrast in healthy myocardium. METHODS: We developed a spatial-spectral (SPSP) saturation pulsed CEST protocol to compensate for B1 variation. Flip angle maps were used to individually tailor SPSP pulses comprised of a train of one-dimensional spatially selective subpulses selective along the principal B1 gradient dimension. Complete Z-spectra in the hearts of (n = 10) healthy individuals were acquired using conventional Gaussian saturation and SPSP schemes and supported by phantom studies. RESULTS: In simulations, the use of SPSP pulses reduced the average SD of the effective saturation B1 values within the myocardium (n = 10) from 0.12 ± 0.02 µT to 0.05 ± 0.01 µT (p < 0.01) and reduced the average SD of Cr CEST contrast in vivo from 10.0 ± 4.3% to 6.1 ± 3.5% (p < 0.05). Results from the hearts of human subjects showed a significant reduction of CEST contrast distribution at 2 ppm, as well as amplitude, when using SPSP saturation. Corresponding phantom experiments revealed PCr-specific contrast generation at body temperature when SPSP saturation was used but combined PCr and Cr contrast generation when Gaussian saturation was used. CONCLUSION: The use of SPSP saturation pulsed CEST resulted in PCr-specific contrast generation and enabled ratiometric mapping of PCr to total Cr CEST contrast in the human heart at 3T.

Detection of laser-associated heating in the brain during simultaneous fMRI and optogenetic stimulation.

PURPOSE: To calculate temperatures from T2 *-weighted images collected during optogenetic fMRI based on proton resonance frequency (PRF) shift thermometry, to monitor confounding heating effects and determine appropriate light parameters for optogenetic stimulation. METHODS: fMRI is mainly based on long-TE gradient-recalled echo acquisitions that are also suitable for measuring small temperature changes via the PRF shift. A motion- and respiration-robust processing pipeline was developed to calculate temperature changes based on the PRF shift directly from the T2 *-weighted images collected for fMRI with a two-shot 2D gradient-recalled echo-EPI sequence at 9.4T. Optogenetic fMRI protocols which differed in stimulation durations (3, 6 and 9 s) within a total block duration of 30 s were applied in a squirrel monkey to validate the methods with blue and green light (20 Hz, 30 mW) delivery interleaved between periods. General linear modeling was performed on the resulting time series temperature maps to verify if light delivery with each protocol resulted in significant heating in the brain around the optical fiber. RESULTS: The temperature SD was 0.05°C with the proposed imaging protocol and processing. Statistical analysis showed that the optogenetic stimulation protocol with a 3 s stimulation duration did not result in significant temperature rises. Significant temperature rises up to 0.13°C (p < 0. 05) were observed with 6 and 9 s stimulation durations for blue and green light. CONCLUSION: The proposed processing pipeline can be useful for the design of optogenetic stimulation protocols and for monitoring confounding heating effects.

Evaluating the efficacy and timing of blood purification modalities in early-stage hyperlipidemic acute pancreatitis treatment.

Hypertriglyceridemia-induced acute pancreatitis (HTG-AP) is characterized by a violent cytokine storm-driven inflammation and is associated with a predisposition to severe disease. The treatment strategy for HTG-AP consists mainly of conventional symptomatic and lipid-lowering treatments. For early-stage HTG-AP, blood purification (BP) can rapidly and effectively reduce serum triglyceride and inflammatory cytokine levels, block the development of systemic inflammatory response syndrome, and improve patient outcomes. Currently, the primary modalities for BP in patients with HTG-AP include plasma exchange, hemoperfusion, and hemofiltration. When using BP to treat patients with HTG-AP, a comprehensive analysis incorporating the elevated lipid levels and severity of the patient's condition contributes to the selection of different treatment modes. Moreover, the timing of the treatment is also imperative. Early intervention is associated with a better prognosis for patients with HTG-AP requiring lipid-lowering treatment.

Semiconductor Optical Amplifier (SOA)-Driven Reservoir Computing for Dense Wavelength-Division Multiplexing (DWDM) Signal Compensation.

Optical signal processing (OSP) technology is a crucial part of the optical switching node in the modern optical-fiber communication system, especially when advanced modulation formats, e.g., quadrature amplitude modulation (QAM), are applied. However, the conventional on-off keying (OOK) signal is still widely used in access or metro transmission systems, which leads to the compatibility requirement of OSP for incoherent and coherent signals. In this paper, we propose a reservoir computing (RC)-OSP scheme based on nonlinear mapping behavior through a semiconductor optical amplifier (SOA) to deal with the non-return-to-zero (NRZ) signals and the differential quadrature phase-shift keying (DQPSK) signals in the nonlinear dense wavelength-division multiplexing (DWDM) channel. We optimized the key parameters of SOA-based RC to improve compensation performance. Based on the simulation investigation, we observed a significant improvement in signal quality over 10 dB compared to the distorted signals on each DWDM channel for both the NRZ and DQPSK transmission cases. The compatible OSP achieved by the proposed SOA-based RC could be a potential application of the optical switching node in the complex optical fiber communication system, where incoherent and coherent signals meet.

Reduced-field of view three-dimensional MR acoustic radiation force imaging with a low-rank reconstruction for targeting transcranial focused ultrasound.

PURPOSE: To rapidly image and localize the focus in MR-guided focused ultrasound (FUS) while maintaining a low ultrasound duty cycle to minimize tissue effects. METHODS: MR-acoustic radiation force imaging (ARFI) is key to targeting FUS procedures such as neuromodulation, and works by encoding ultrasound-induced displacements into the phase of MR images. However, it can require long scan times to cover a volume of tissue, especially when minimizing the FUS dose during targeting is paramount. To simultaneously minimize scan time and the FUS duty cycle, a 2-min three-dimensional (3D) reduced-FOV spin echo ARFI scan with two-dimensional undersampling was implemented at 3T with a FUS duty cycle of 0.85%. The 3D k-space sampling scheme incorporated uniform undersampling in one phase-encoded axis and partial Fourier (PF) sampling in the other. The scan interleaved FUS-on and FUS-off data collection to improve displacement map quality via a joint low-rank image reconstruction. Experiments in agarose and graphite phantoms and living macaque brains for neuromodulation and blood-brain barrier opening studied the effects of the sampling and reconstruction strategy on the acquisition, and evaluated its repeatability and accuracy. RESULTS: In the phantom, the distances between displacement centroids of 10 prospective reconstructions and a fully sampled reference were below 1 mm. In in vivo brain, the distances between centroids ranged from 1.3 to 2.1 mm. Results in phantom and in vivo brain both showed that the proposed method can recover the FUS focus compared to slower fully sampled scans. CONCLUSION: The proposed 3D MR-ARFI reduced-FOV method enables rapid imaging of the FUS focus while maintaining a low FUS duty cycle.

A novel methodology concentrating on risk propagation to conduct a risk analysis based on a directed complex network.

A novel methodology is proposed in the present study to describe the risk propagation process by quantitatively evaluating the criticality and sensitivity of risk events according to complex network theory, based on which risk matrices are developed to interrupt the risk propagation process by setting up safety barriers. The applicability and accuracy of the improved k-shell decomposition algorithm and risk flow model for calculating the criticality proposed in this study are verified by the susceptible-infected-recovered (SIR) simulation, which is widely regarded as a benchmark for complex networks (CN) issues. The results confirm the advantages of the proposed methodologies considering comprehensively various comparison indicators. The sensitivity of the nodes is quantified by running an SIR simulation with a variable infection rate and recovery rate. Finally, the criticality and sensitivity of risk events contribute to the development of risk matrices with three different risk scenarios, based on which the applicability and effectiveness of safety barriers are qualitatively analyzed to interrupt the risk propagation process. The framework and methodologies proposed in this study could well present the risk propagation process within CNs and are proven to have a great potential for studies on safety barriers.

Free-breathing liver fat and R2∗ quantification using motion-corrected averaging based on a nonlocal means algorithm.

PURPOSE: To propose a motion-robust chemical shift-encoded (CSE) method with high signal-to-noise (SNR) for accurate quantification of liver proton density fat fraction (PDFF) and R2∗ . METHODS: A free-breathing multi-repetition 2D CSE acquisition with motion-corrected averaging using nonlocal means (NLM) was proposed. PDFF and R2∗ quantified with 2D CSE-NLM were compared to two alternative 2D techniques: direct averaging and single acquisition (2D 1ave) in a digital phantom. Further, 2D NLM was compared in patients to 3D techniques (standard breath-hold, free-breathing and navigated), and the alternative 2D techniques. A reader study and quantitative analysis (Bland-Altman, correlation analysis, paired Student's t-test) were performed to evaluate the image quality and assess PDFF and R2∗ measurements in regions of interest. RESULTS: In simulations, 2D NLM resulted in lower standard deviations (STDs) of PDFF (2.7%) and R2∗ (8.2  s-1 ) compared to direct averaging (PDFF: 3.1%, R2∗ : 13.6  s-1 ) and 2D 1ave (PDFF: 8.7%, R2∗ : 33.2  s-1 ). In patients, 2D NLM resulted in fewer motion artifacts than 3D free-breathing and 3D navigated, less signal loss than 2D direct averaging, and higher SNR than 2D 1ave. Quantitatively, the STDs of PDFF and R2∗ of 2D NLM were comparable to those of 2D direct averaging (p>0.05). 2D NLM reduced bias, particularly in R2∗ (-5.73 to -0.36  s-1 ) that arises in direct averaging (-3.96 to 11.22  s-1 ) in the presence of motion. CONCLUSIONS: 2D CSE-NLM enables accurate mapping of PDFF and R2∗ in the liver during free-breathing.

Development and validation of an automated assessment tool of echocardiography skills acquired on a neonatal simulator.

INTRODUCTION: Simulators are increasingly used for training in echocardiography. However, there is no objective method to assess the skills acquired. Our objective was to develop and test an automated method to assess echocardiography skills. METHODS: To automate the image quality evaluation, we expanded our previously developed neonatal echocardiography simulator to enable recording of images of the 26 standard cuts and process the image quality. We then compared the automated and visual methods in scoring image quality of the echocardiograms obtained by 22 trainees. RESULTS: Each echocardiographic image representing a slice of a three-dimensional volume possesses 3 axes (X, Y, and Z) that correspond to the roll, pitch, and yaw angles of the transducer, respectively. Therefore, if the placement and orientation of the transducer are correct, the acquired image represents the appropriate cardiac window with the desired orientation in all 3 axes. The automated system gives a score of 0 if the transducer is not in the appropriate cardiac window. A score of 1, 2, or 3 is given if the image falls within the range of one, two, or three angles, respectively. There was no difference in the image quality score between automated and visual assessment methods (46.0 ± 13.0 vs 45.1 ± 14.4, P = .19). The two methods had excellent correlation (r = .95). The bias and precision were 0.9 and 8.8, respectively. CONCLUSIONS: The automated method is comparable to visual method for assessment of image quality. The automated process allows for instantaneous feedback and has the potential to standardize assessment of echocardiography skills of trainees.

Association of shared decision making with inpatient satisfaction: a cross-sectional study.

BACKGROUND: We assessed inpatient perceived shared decision making (SDM) and tested the association of SDM with inpatient satisfaction in public tertiary hospitals in Shanghai, China. METHODS: A cross-sectional survey of 2585 inpatients in 47 public tertiary hospitals in Shanghai in July and August 2018 was conducted. We assessed overall SDM and 4 aspects of SDM and tested the factors influencing SDM and the association of SDM with patient satisfaction (patient satisfaction with physician services, medical expenses, outcomes and overall inpatient care), by adopting linear or two-level regression models. RESULTS: The positive response rate (PRR) and high positive response rate (HPRR) to overall SDM among the inpatients of public tertiary hospitals in Shanghai were relatively high (95.30% and 87.86%, respectively), while the HPRR to "My physician informed me of different treatment alternatives" was relatively low (80.09%). In addition, the inpatients who underwent surgery during admission had higher HPRRs and adjusted HPRRs to overall SDM than those who did not undergo surgery. The study showed that the adjusted high satisfaction rates (HSRs) with physician services, medical expenses, outcomes and overall inpatient care among the inpatients with high level of overall SDM were higher (96.50%, 68.44%, 89.50% and 92.60%) than those among the inpatients without a high level of overall SDM (71.77%, 35.19%, 57.30% and 67.49%). The greatest differences in the adjusted HSRs between the inpatients with and without a high level of SDM were found in inpatient satisfaction with medical expenses and informed consent in SDM. Moreover, 46.22% of the variances in the HSRs with overall inpatient care across the hospitals were attributed to the hospital type (general hospitals vs. specialty hospitals). CONCLUSIONS: Inpatient PRRs and HPRRs to SDM in public tertiary hospitals in Shanghai are relatively high overall but lower to information regarding alternatives. SDM can be affected by the SDM preference of both the patients and physicians and medical condition. Patient satisfaction can be improved through better SDM and should be committed at the hospital level.

Rapid quantitative imaging of high intensity ultrasonic pressure fields.

High intensity focused ultrasound (FUS) is a noninvasive technique for treatment of tissues that can lie deep within the body. There is a need for methods to rapidly and quantitatively map FUS pressure beams for quality assurance and accelerate development of FUS systems and techniques. However, conventional ultrasound pressure beam mapping instruments, including hydrophones and optical techniques, are slow, not portable, and expensive, and most cannot map beams at actual therapeutic pressure levels. Here, a rapid projection imaging method to quantitatively map FUS pressure beams based on continuous-wave background-oriented schlieren (CW-BOS) imaging is reported. The method requires only a water tank, a background pattern, and a camera and uses a multi-layer deep neural network to reconstruct two-dimensional root-mean-square (RMS) projected pressure maps that resolve the ultrasound propagation dimension and one lateral dimension. In this work, the method was applied to collect beam maps over a 3 × 1 cm2 field-of-view with 0.425 mm resolution for focal pressures up to 9 MPa. Results at two frequencies and comparisons to hydrophone measurements show that CW-BOS imaging produces high-resolution quantitative RMS projected FUS pressure maps in under 10 s, the technique is linear and robust to beam rotations and translations, and it can map aberrated beams.

40 nm thick photoresist-compatible plasmonic nanolithography using a bowtie aperture combined with a metal-insulator-metal structure.

In this Letter, 40 nm thick photoresist (PR)-compatible plasmonic nanolithography using a bowtie aperture incorporated with a metal-insulator-metal (MIM) structure is studied numerically and experimentally. The simulation results show that with a 20 nm index-matching layer, the light field that exits from the bowtie aperture penetrates into a 40 nm thick PR by using a MIM configuration. Imaging contrast calculations indicate that sub-45 nm resolution with an exposure depth in the order of tens of nanometers is achievable, which is confirmed by the experimental results. In addition, the ability to generate high-resolution, complex patterns using this technique via scanning is demonstrated. This brings plasmonic nanolithography using a bowtie aperture one step closer to practical applications.

Deep plasmonic direct writing lithography with ENZ metamaterials and nanoantenna.

In this article, we demonstrate a specially designed resonant metamaterial with epsilon-near-zero (ENZ) and nanoantenna to enhance the exposure depth in plasmonic direct writing lithography more than 10 times. The ENZ metamaterial composed of a Ag/Si3N4 multilayer thin film, converts the evanescent field generated by the bowtie aperture nanoantenna to propagating waves with low divergence and high collimation. Deep sub-diffraction limited resolution of less than 65 nm (λ/7) with exposure depth greater than 100 nm is achieved. This work brings plasmonic direct writing lithography one step closer to practical applications.

Flexible devices fabricated by a plate-to-roll nanoimprint lithography system.

A plate-to-roll nanoimprint lithography (P2RNIL) system has been developed to realize a high-speed, large-scale and high-resolution nanoimprint process. Imprinted patterns have been achieved with a linewidth of less than 75 nm at a speed of 22 cm2 s-1 on flexible substrate. To improve the quality of the imprinted patterns, we have proposed a compliant mechanism which can realize passive alignment and minimize the lateral displacement between template and substrate. Finite element analysis of this compliant mechanism was carried out. By using the P2RNIL system, wire-grid polarizers (up to a 10 030:1 extinction ratio and up to 88% transmittance) and transparent metal electrodes whose performance is in good accordance with simulated results were successfully fabricated.

Optical field manipulation by dual magnetic resonances of a silicon metasurface.

In this Letter, we study the influence of magnetic mode dispersion on the performance of a metasurface cylindrical vector beam (CVB) generator. An optical field after a metasurface CVB generator can be manipulated by polarization-dependent transmittance arising from dual magnetic resonance of silicon nanopillars. A perfect CVB is only generated when the transmittances are equal for two orthogonal polarization. Two magnetic resonant wavelengths can be spatially separated because of the coherent superposition between the residual incident light and the generating CVB, which is potentially useful for a compact multiplex color router.

Exotic Spectra and Lattice Vibrations of Ice X Using the DFT Method.

A typical vibrational spectrum in the ice phase has four separate bands: Translation, libration, bending, and stretching. Ice X, the final ice phase under high pressure, shows an exotic vibrational spectrum. Based on harmonic approximation, an ideal crystal of ice X has one peak, at 998 cm-1, for Raman scattering and two peaks, at 450 cm-1 and 1507 cm-1, for infrared absorption in this work. These three characteristic peaks are indicators of the phase transition between ice VII and VIII and ice X. Despite many experimental and theoretical works on ice X, only this study has clearly indicated these characteristic peaks in the region of the IR band. The phonon density of states shows quite different features than ice VIII, which could be verified by inelastic neutron scattering in the future. The dynamic processes of 15 vibrational normal modes are discussed and the typical hydrogen bonds are missing.

Adrenaline promotes epithelial-to-mesenchymal transition via HuR-TGFß regulatory axis in pancreatic cancer cells and the implication in cancer prognosis.

Psychological stress has recently been described as a risk factor in the development of pancreatic cancer. Here, we reported that increased neurotransmitter adrenaline was associated with the poor survival in pancreatic cancer patients. Moreover, in the cell model study, we found adrenaline promoted pancreatic cell PANC-1 migration in a dose dependent manner. Block of the ß2-adrenoreceptor with ICI118,551, significantly reduced cell migration. Further study found that adrenaline induced a cytoplasmic translocation of RNA binding protein HuR, which in turn activated TGFß, as shown by the SBE luciferase assay and phosphorylation of Smad2/3. Either HuR knockdown or TGFß inhibition reduced cell migration induced by adrenaline. Taken together, our study here revealed that adrenaline-HuR-TGFß regulatory axis at least partially contributes to the psychological stress induced metastasis in PANC-1 cells, shedding light on therapeutic targeting psychological stress in improving the prognosis of pancreatic cancer.

Cost-effectiveness analysis of different types of human papillomavirus vaccination combined with a cervical cancer screening program in mainland China.

BACKGROUND: China has a high prevalence of human papillomavirus (HPV) and a consequently high burden of disease with respect to cervical cancer. The HPV vaccine has proved to be effective in preventing cervical cancer and is now a part of routine immunization programs worldwide. It has also proved to be cost effective. This study aimed to assess the cost-effectiveness of 2-, 4-, and 9-valent HPV vaccines (hereafter, HPV2, 4 or 9) combined with current screening strategies in China. METHODS: A Markov model was developed for a cohort of 100,000 HPV-free girls to simulate the natural history to HPV infection. Three recommended screening methods (1. liquid-based cytology test + HPV DNA test; 2. pap smear cytology test + HPV DNA test; 3. visual inspection with acetic acid) and three types of HPV vaccination program (HPV2/4/9) were incorporated into 15 intervention options, and the incremental cost-effectiveness ratio (ICER) was calculated to determine the dominant strategies. Costs, transition probabilities and utilities were obtained from a review of the literature and national databases. One-way sensitivity analyses and threshold analyses were performed for key variables in different vaccination scenarios. RESULTS: HPV9 combined with screening showed the highest health impact in terms of reducing HPV-related diseases and increasing the number of quality-adjusted life years (QALYs). Under the current thresholds of willingness to pay (WTP, 3 times the per capita GDP or USD$ 23,880), HPV4/9 proved highly cost effective, while HPV2 combined with screening cost more and was less cost effective. Only when screening coverage increased to 60% ~ 70% did the HPV2 and screening combination strategy become economically feasible. CONCLUSIONS: The combination of the HPV4/9 vaccine with current screening strategies for adolescent girls was highly cost-effective and had a significant impact on reducing the HPV infection-related disease burden in Mainland China.

Do different parenting patterns impact the health and physical growth of 'left-behind' preschool-aged children? A cross-sectional study in rural China.

BACKGROUND: Many migrants from rural China seek work in urban areas and leave their children in their home villages to be raised by relatives. These children are often referred to as 'left-behind children'. Parental migration tends to have a profound impact on a child's growth. This study sought to assess the prevalence of illness and malnutrition among children in rural areas raised with different parenting patterns and to explore factors affecting their health and development. METHOD: A cross-sectional survey was conducted to examine the physical health of children raised with different parenting patterns and to explore associated risk factors. In total, this study examined 735 children ages 3-6 years in eight rural villages in two counties of Shandong Province. Their primary caregivers were interviewed with a semi-structured questionnaire. Anthropometric measurements of the children were taken and their nutritional status was determined according to WHO Child Growth Standards. RESULTS: This study found a relatively high prevalence of wasting, overweight and obesity among left-behind children. After potential confounders were controlled for, the parenting pattern, annual household income and health literacy of the primary caregiver significantly influenced the health and developmental indicators of children. CONCLUSIONS: This study highlighted the impact of the characteristics of the primary caregiver on a child's health and development and the importance of practical interventions for preschool-aged children who are left behind and raised with different parenting patterns.

Clinical significance of small extracellular vesicles in cholangiocarcinoma.

Cholangiocarcinoma is an aggressive and heterogeneous malignancy originating from the bile duct epithelium. It is associated with poor prognosis and high mortality. The global incidence of cholangiocarcinoma is rising, and there is an urgent need for effective early diagnosis and treatment strategies to reduce the burden of this devastating tumor. Small extracellular vesicles, including exosomes and microparticles, are nanoscale vesicles formed by membranes that are released both normally and pathologically from cells, mediating the intercellular transfer of substances and information. Recent studies have demonstrated the involvement of small extracellular vesicles in numerous biological processes, as well as the proliferation, invasion, and metastasis of tumor cells. The present review summarizes the tumorigenic roles of small extracellular vesicles in the cholangiocarcinoma microenvironment. Owing to their unique composition, accessibility, and stability in biological fluids, small extracellular vesicles have emerged as ideal biomarkers for use in liquid biopsies for diagnosing and outcome prediction of cholangiocarcinoma. Specific tissue tropism, theoretical biocompatibility, low clearance, and strong biological barrier penetration of small extracellular vesicles make them suitable drug carriers for cancer therapy. Furthermore, the potential value of small extracellular vesicle-based therapies for cholangiocarcinoma is also reviewed.