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In vivo quantification of the structural changes of collagens in a melanoma microenvironment with second and third harmonic generation microscopy.

Wu PC, Hsieh TY, Tsai ZU, Liu TM - Sci Rep (2015)

Bottom Line: The corresponding GLCM traces showed oscillation features and the sum of squared fluctuation VarGLCM increased with the tumor sizes.In addition, the THG intensities of the extracellular matrices increased, indicating an enhanced optical inhomogeneity.We believe these indices have the potential to help the diagnosis of skin cancers in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan.

ABSTRACT
Using in vivo second harmonic generation (SHG) and third harmonic generation (THG) microscopies, we tracked the course of collagen remodeling over time in the same melanoma microenvironment within an individual mouse. The corresponding structural and morphological changes were quantitatively analyzed without labeling using an orientation index (OI), the gray level co-occurrence matrix (GLCM) method, and the intensity ratio of THG to SHG (RTHG/SHG). In the early stage of melanoma development, we found that collagen fibers adjacent to a melanoma have increased OI values and SHG intensities. In the late stages, these collagen networks have more directionality and less homogeneity. The corresponding GLCM traces showed oscillation features and the sum of squared fluctuation VarGLCM increased with the tumor sizes. In addition, the THG intensities of the extracellular matrices increased, indicating an enhanced optical inhomogeneity. Multiplying OI, VarGLCM, and RTHG/SHG together, the combinational collagen remodeling (CR) index at 4 weeks post melanoma implantation showed a 400-times higher value than normal ones. These results validate that our quantitative indices of SHG and THG microscopies are sensitive enough to diagnose the collagen remodeling in vivo. We believe these indices have the potential to help the diagnosis of skin cancers in clinical practice.

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Related in: MedlinePlus

The (a) OI values, (b) GLCM traces, (c) VarGLCM values, and (d) RTHG/SHG values of the collagen networks revealed by the in vivo SHG images of mice before the melanoma implantation and at 2 weeks, 3 weeks, and 4 weeks post melanoma implantation.The areas with dense blue lines indicate the ranges of the baseline variation. The bars indicate the variation among different depths.
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f8: The (a) OI values, (b) GLCM traces, (c) VarGLCM values, and (d) RTHG/SHG values of the collagen networks revealed by the in vivo SHG images of mice before the melanoma implantation and at 2 weeks, 3 weeks, and 4 weeks post melanoma implantation.The areas with dense blue lines indicate the ranges of the baseline variation. The bars indicate the variation among different depths.

Mentions: Understanding the range of baseline values for each quantitation method, we then tracked the tumor associated collagen at the fix position of the same mouse for four weeks. Before the implantation of the melanoma cells, the collagen OI was approximately 38%. At the 3 weeks post melanoma implantation, the OI increased to approximately 58% (Fig. 8a). This difference is significantly higher than the baseline variation (area with dense blue lines in Fig. 8a). In the GLCM analyses, we found that the short-distance correlation of the collagen textures declined faster as the tumor grew (Fig. 8b). At 4 weeks post-implantation, the correlation fell below 0.5 at a distance 30% shorter than that before the melanoma implantation. Another tumor-related feature is the oscillation of GLCM traces. To quantitatively analyze the oscillation of GLCM traces, we removed the slow varying background of GLCM traces (Fig. S6) and calculated the corresponding VarGLCM. The value was increased quickly from 0.015 to 0.078, which was quite sensitive to the tumor growth. The RTHG/SHG started with a low ratio of 0.03 at 2 weeks and then increased to 1.21 at 4 weeks post-implantation. The value at the fourth week was obviously higher than the baseline values.


In vivo quantification of the structural changes of collagens in a melanoma microenvironment with second and third harmonic generation microscopy.

Wu PC, Hsieh TY, Tsai ZU, Liu TM - Sci Rep (2015)

The (a) OI values, (b) GLCM traces, (c) VarGLCM values, and (d) RTHG/SHG values of the collagen networks revealed by the in vivo SHG images of mice before the melanoma implantation and at 2 weeks, 3 weeks, and 4 weeks post melanoma implantation.The areas with dense blue lines indicate the ranges of the baseline variation. The bars indicate the variation among different depths.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352861&req=5

f8: The (a) OI values, (b) GLCM traces, (c) VarGLCM values, and (d) RTHG/SHG values of the collagen networks revealed by the in vivo SHG images of mice before the melanoma implantation and at 2 weeks, 3 weeks, and 4 weeks post melanoma implantation.The areas with dense blue lines indicate the ranges of the baseline variation. The bars indicate the variation among different depths.
Mentions: Understanding the range of baseline values for each quantitation method, we then tracked the tumor associated collagen at the fix position of the same mouse for four weeks. Before the implantation of the melanoma cells, the collagen OI was approximately 38%. At the 3 weeks post melanoma implantation, the OI increased to approximately 58% (Fig. 8a). This difference is significantly higher than the baseline variation (area with dense blue lines in Fig. 8a). In the GLCM analyses, we found that the short-distance correlation of the collagen textures declined faster as the tumor grew (Fig. 8b). At 4 weeks post-implantation, the correlation fell below 0.5 at a distance 30% shorter than that before the melanoma implantation. Another tumor-related feature is the oscillation of GLCM traces. To quantitatively analyze the oscillation of GLCM traces, we removed the slow varying background of GLCM traces (Fig. S6) and calculated the corresponding VarGLCM. The value was increased quickly from 0.015 to 0.078, which was quite sensitive to the tumor growth. The RTHG/SHG started with a low ratio of 0.03 at 2 weeks and then increased to 1.21 at 4 weeks post-implantation. The value at the fourth week was obviously higher than the baseline values.

Bottom Line: The corresponding GLCM traces showed oscillation features and the sum of squared fluctuation VarGLCM increased with the tumor sizes.In addition, the THG intensities of the extracellular matrices increased, indicating an enhanced optical inhomogeneity.We believe these indices have the potential to help the diagnosis of skin cancers in clinical practice.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan.

ABSTRACT
Using in vivo second harmonic generation (SHG) and third harmonic generation (THG) microscopies, we tracked the course of collagen remodeling over time in the same melanoma microenvironment within an individual mouse. The corresponding structural and morphological changes were quantitatively analyzed without labeling using an orientation index (OI), the gray level co-occurrence matrix (GLCM) method, and the intensity ratio of THG to SHG (RTHG/SHG). In the early stage of melanoma development, we found that collagen fibers adjacent to a melanoma have increased OI values and SHG intensities. In the late stages, these collagen networks have more directionality and less homogeneity. The corresponding GLCM traces showed oscillation features and the sum of squared fluctuation VarGLCM increased with the tumor sizes. In addition, the THG intensities of the extracellular matrices increased, indicating an enhanced optical inhomogeneity. Multiplying OI, VarGLCM, and RTHG/SHG together, the combinational collagen remodeling (CR) index at 4 weeks post melanoma implantation showed a 400-times higher value than normal ones. These results validate that our quantitative indices of SHG and THG microscopies are sensitive enough to diagnose the collagen remodeling in vivo. We believe these indices have the potential to help the diagnosis of skin cancers in clinical practice.

Show MeSH
Related in: MedlinePlus