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The current technology has limited ability to detect lateral thermal spread of injury caused by electrosurgical devices during gynecologic procedures.
Aim
We aim to assess the feasibility of endoscopic optical coherence tomography (OCT) to detect electrothermal ureteral damage.
Approach
Electrothermal energy was externally applied to nine explanted porcine ureters. Three segments of each ureter were treated for 5 s at low (16 W), medium (26 W), and high (36 W) powers (n=27 segments). Volumetric OCT images were acquired using a swept source OCT laser endomicroscopy system. OCT datasets were visually inspected for characterization of normal and electrothermally injured tissue architecture. Ground-truth comparisons were made with histology to validate the presence of lesions and to compare lesion size measurements using Pearson’s correlation coefficient. Three physicians were trained to identify OCT images of normal and injured ureters. Physician lesion detection accuracy was tested with 126 OCT images (63 normal and 63 injured). The effect of treatment power on lesion length as measured with OCT was compared using a one-way analysis of variance.
Results
Transmural electrothermal injury was identified on OCT images for all but one histology-confirmed lesion (22/23, 95.7%). The average sensitivity and specificity for physician lesion detection were 82% and 96%, respectively. The mean lesion size measured on OCT was 3.6±1.9, 4.4±1.3, and 7.0±2.9mm for low, medium, and high powers, respectively (p=0.024). A comparison of lesion size measured on OCT and histology revealed a moderate positive correlation (r=0.65, p=0.00087).
Conclusions
Endoscopic OCT could fulfill the unmet clinical need for the timely detection of electrothermal ureteral injury.
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Heart disease is the leading cause of death in the United States, yet research is limited by the inability to culture primary cardiac cells. Cardiomyocytes (CMs) derived from human induced pluripotent stem cells (iPSCs) are a promising solution for drug screening and disease modeling.
Aim
Induced pluripotent stem cell-derived CM (iPSC-CM) differentiation and maturation studies typically use heterogeneous substrates for growth and destructive verification methods. Reproducible, tunable substrates and touch-free monitoring are needed to identify ideal conditions to produce homogenous, functional CMs.
Approach
We generated synthetic polyethylene glycol-based hydrogels for iPSC-CM differentiation and maturation. Peptide concentrations, combinations, and gel stiffness were tuned independently. Label-free optical redox imaging (ORI) was performed on a widefield microscope in a 96-well screen of gel formulations. We performed live-cell imaging throughout differentiation and early to late maturation to identify key metabolic shifts.
Results
Label-free ORI confirmed the expected metabolic shifts toward oxidative phosphorylation throughout the differentiation and maturation processes of iPSC-CMs on synthetic hydrogels. Furthermore, ORI distinguished high and low differentiation efficiency cell batches in the cardiac progenitor stage.
Conclusions
We established a workflow for medium throughput screening of synthetic hydrogel conditions with the ability to perform repeated live-cell measurements and confirm expected metabolic shifts. These methods have implications for reproducible iPSC-CM generation in biomanufacturing.
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Radiation resistance is a major contributor to cancer treatment failure and is likely driven by multiple pathways. Multivariate visualization that preserves the spatial co-localization of factors could aid in understanding mechanisms of resistance and identifying biomarkers of response.
Aim
We aim to investigate the spatial and temporal relationship between hypoxia, hypoxia-inducible factor 1 (HIF-1α), and metabolism in response to radiation therapy in two cell lines of known radiation resistance and sensitivity.
Approach
Two-photon excited fluorescence and fluorescence lifetime imaging microscopy were used to quantify the optical redox ratio (ORR) and NAD(P)H fluorescent lifetime and bound fraction in frozen tumor sections and co-registered with immunohistochemical stain-based imaging of hypoxic fraction and HIF-1α.
Results
Histogram analysis of hypoxia, HIF-1α, and ORR revealed an increase in the ORR in regions of low hypoxia and high HIF-1α, indicating that the stabilization of HIF-1α is likely due to an increase in reactive oxygen species following radiation therapy. In addition, the bound NAD(P)H fraction was higher in regions with a low ORR in resistant tumors following radiation, suggesting an increase in fatty acid synthesis.
Conclusions
A multivariate histogram approach can reveal hidden trends not observed in bulk analysis of tumor images and may be useful in understanding biomarkers and mechanisms of radiation resistance.
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Increased collagen linearization and deposition during tumorigenesis can impede immune cell infiltration and lead to tumor metastasis. Although melanoma is well studied in immunotherapy research, studies that quantify collagen changes during melanoma progression and treatment are lacking.
Aim
We aim to image in vivo collagen in preclinical melanoma models during immunotherapy and quantify the collagen phenotype in treated and control mice.
Approach
Second-harmonic generation imaging of collagen was performed in mouse melanoma tumors in vivo over a treatment time course. Animals were treated with a curative radiation and immunotherapy combination. Collagen morphology was quantified over time at an image and single-fiber level using CurveAlign and CT-FIRE software.
Results
In immunotherapy-treated mice, collagen was reorganized toward a healthy phenotype, including shorter, wider, curlier collagen fibers, with modestly higher collagen density. Temporally, collagen fiber straightness and length changed late in treatment (days 9 and 12), while width and density changed early (day 6) compared with control mice. Single-fiber collagen features calculated in CT-FIRE were the most sensitive to the changes among treatment groups compared with bulk collagen features.
Conclusions
Quantitative second-harmonic generation imaging can provide insight into collagen dynamics in vivo during immunotherapy, with key implications in improving immunotherapy response in melanoma and other cancers.
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