Core Concepts
Photoacoustic spectral analysis (PASA) is a promising non-invasive technique for longitudinally monitoring collagen evolution in breast cancers, particularly in the context of cancer-associated fibroblast (CAF) modulated tumor microenvironment.
Abstract
Bibliographic Information:
Li, J., Zhi, W., Bai, L., Cheng, Q., & Cao, J. (Year of Publication). Longitudinal photoacoustic monitoring of collagen evolution modulated by cancer-associated fibroblasts: simulation and experiment studies. Journal Name, Volume Number(Issue Number), Page Numbers.
Research Objective:
This study aimed to investigate the feasibility of using photoacoustic spectral analysis (PASA) for longitudinal monitoring of collagen changes in murine breast cancers, specifically focusing on the influence of cancer-associated fibroblasts (CAFs).
Methodology:
The research employed a two-pronged approach:
- Simulations: Optical and acoustic simulations were conducted using histological slides of murine breast cancers to model light diffusion and PA signal propagation. The simulations aimed to verify the effectiveness of the PA detection system and the "relative area of power spectrum density (APSD)" parameter for quantifying collagen.
- In vivo Experiments: Three groups of nude mice with breast cancer models were established, each with varying ratios of CAFs and cancer cells. In vivo PA measurements were taken at three time points as the tumors grew.
Key Findings:
- Simulations: Demonstrated that collagen generates a stronger PA signal compared to other tumor tissues at 1580 nm, and the initial PA pressure decreases with tissue depth. A linear relationship was observed between relative collagen content and relative APSD, suggesting APSD's reliability in quantifying collagen changes.
- In vivo Experiments: Showed an increasing trend in relative APSD for groups with lower CAF ratios, indicating collagen growth. However, the group with the highest CAF ratio exhibited a decreasing APSD trend, suggesting CAF-mediated collagen suppression.
Main Conclusions:
The study concludes that PASA, coupled with the APSD parameter, holds significant potential for non-invasive, longitudinal monitoring of collagen evolution in breast cancers. The findings also highlight the crucial role of CAFs in extracellular matrix remodeling and suggest potential for CAF-targeted therapies monitored by PASA.
Significance:
This research contributes significantly to the field of oncology by presenting PASA as a promising tool for monitoring tumor progression and treatment response, particularly in therapies targeting the tumor microenvironment.
Limitations and Future Research:
The study acknowledges limitations in the simulation models and suggests improvements for future research, including using 3D models and incorporating more histological data. Further in vivo studies with additional time points and histological validation are recommended to confirm the findings and explore the therapeutic potential of targeting CAFs.
Stats
The photoenergy of a 1580 nm laser reduced to e-1 of its surface value at depths of 2.04, 2.34, and 2.23 mm in cancers owning diameters of 8, 12, and 16 mm, respectively.
The water content was considered to be 20% for normal tissues and 9% for malignant tissues.
The values for collagen volume fraction and lipid volume fraction were defined as 5% and 8% in normal tissues, while 10% and 3% in malignancies.
Quotes
"The presented methods show great potential for clinical translation of PASA in the field of cancer therapies targeting CAFs."
"CAF-modulated ECM synthesis and remodeling can be detected in vivo using second harmonic generation imaging microscopy (SHIM) and shear wave imaging (SWI). However, the capabilities of SHIM and SWI are constrained by their shallow detection depth and lack of direct validation."