Measuring Fibrosis in Mice: FibroScan, PRO-C3, ELF Score
Cross the preclinical-clinical gap with the same measures as trials. Non-invasive biomarkers: FibroScan (CAP/VCTE), PRO-C3, ELF score for MASH fibrosis.
Lead: The biggest difference between preclinical studies (animal experiments) and clinical trials implies "timing and invasiveness of evaluation." In animal experiments, it is common to remove and evaluate the liver at "necropsy on the final day," but performing liver biopsy every time in human clinical trials is ethically and practically difficult. Currently, non-invasive examination devices like FibroScan® and blood biomarkers are becoming standard in clinical settings. In this article, we explain how to incorporate this "clinical measure" into mouse studies to increase the success rate of Translational Research.
Key Takeaways
- Measurement principle of human clinical standard FibroScan (VCTE/CAP)
- Alternative means to perform equivalent evaluation in mice (MRI-PDFF, Micro-elastography)
- Serum biomarkers capturing "Movement of Fibrosis" (PRO-C3, ELF Score)
1. Clinical Gold Standard: FibroScan® (VCTE/CAP)
Echosens' FibroScan® has become an essential device in MASH/NASH and fibrosis clinical trials. The ability to measure the following two parameters simultaneously in just a few minutes is revolutionary.
1. Liver Stiffness Measurement (LSM)
- Technology: VCTE (Vibration-Controlled Transient Elastography)
- Unit: kPa (kilopascal)
- Meaning: Measures "stiffness" of the liver. Since it hardens as fibrosis progresses, it correlates with fibrosis stage (F0-F4).
2. Controlled Attenuation Parameter (CAP)
- Technology: Ultrasonic attenuation measurement
- Unit: dB/m (decibel/meter)
- Meaning: Measures "fat amount (Steatosis)" of the liver. It is an extremely important endpoint for evaluating Lipid reduction effects by drugs in metabolic diseases like MASH.
2. Can FibroScan be Used in Mice?
To conclude, you cannot apply the clinical FibroScan probe directly to mice (because the probe diameter is larger than the mouse liver). However, alternative technologies exist to measure "the same physical quantities (stiffness and fat amount)".
Alternative 1: MRI-PDFF (Proton Density Fat Fraction)
Preclinical Standard for "Fat Quantification"
- Principle: Uses MRI to separate and quantify proton signals of water and fat in the liver.
- Benefits:
- Can visualize the entire liver fat amount as a map (no sampling error).
- Shows extremely high correlation with FibroScan CAP values.
- Since it is completely non-invasive, it is possible to measure the same individual every few weeks and track the "process of fat reduction."
Alternative 2: Micro-elastography (Small Animal Elastography)
Measuring "Stiffness"
- Some manufacturers sell high-frequency ultrasound elastography dedicated to small animals, allowing measurement of mouse liver stiffness (kPa).
- However, technical difficulty such as anesthesia depth and respiratory synchronization is high, and introduction costs tend to be high.
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3. Serum Biomarkers: PRO-C3 and ELF Score
Methods measuring fibrosis dynamics with "blood" rather than "images" are also attracting attention due to high correlation with clinical practice.
PRO-C3 (Type III Collagen Formation Marker)
- "Is fiber being created now?"
- Conventional hydroxyproline quantification measured "total amount of accumulated (past) collagen."
- In contrast, PRO-C3 measures the pro-peptide (Neo-epitope) cleaved when Type III collagen is synthesized. In other words, it reflects "ongoing fibrogenesis activity".
- It excels in early detection that the drug worked and "fibrosis stopped."
ELF™ Score (Enhanced Liver Fibrosis Score)
- An algorithm combining 3 markers (HA, PIIINP, TIMP-1).
- It is discussed as a surrogate endpoint in clinical trials by FDA/EMA, and by measuring similar parameters using mouse ELISA kits, direct comparison with clinical data becomes possible.
- Complete guide: ELF Score: Non-Invasive Biomarker for MASH Liver Fibrosis (formula, clinical cutoffs, and preclinical translation examples)
4. Proposal: Study Design Not Making "Death" the Endpoint
Traditional mouse studies were mainly Cross-sectional evaluations of "End of dosing → Necropsy of all animals → Tissue analysis." However, incorporating non-invasive biomarkers enables Longitudinal studies like the following.
- Before/After Comparison: Since the rate of change (% change) from baseline for each individual can be calculated, the influence of individual differences (variability) can be minimized.
- Prevention of Dropouts: If it turns out "not working" in the interim progress, it becomes material for judging to modify the protocol early.
Conclusion: Bridging the Translational Gap
"Data measured by grinding mouse liver" alone is insufficient to predict drug efficacy in humans. Keeping FibroScan (CAP/LSM) and PRO-C3 used in clinical trials in mind, and incorporating MRI-PDFF and serum markers that correlate with them from the preclinical stage. This becomes the bridge that saves your drug discovery project from the "Valley of Death."
Further Reading
- Pathological Evaluation Methods
- Choosing Models for Clinical Trials
Comparison Table of Methods
| Metric | FibroScan (CAP) | MRI-PDFF | PRO-C3 |
|---|---|---|---|
| Target | Fat Amount (dB/m) | Fat Amount (%) | Fibrogenesis (ng/mL) |
| Subject | Human (Clinical) | Human/Mouse | Human/Mouse |
| Invasiveness | Non-invasive | Non-invasive | Blood sampling only |
| Resolution | Medium (Local) | High (Whole organ map) | None (Systemic total) |
| Cost | Low (if device available) | High (MRI fee) | Medium (ELISA kit) |
| Correlation | ◎ (Gold Standard) | ◎ (High Correlation) | ○ (Surrogate Candidate) |
References
- Siddiqui MS, et al. Vibration-controlled transient elastography to assess fibrosis and steatosis in patients with nonalcoholic fatty liver disease. Clin Gastroenterol Hepatol. 2019;17(1):156-163. PubMed
- Reeder SB, et al. Quantitative assessment of liver fat with magnetic resonance imaging and spectroscopy. J Magn Reson Imaging. 2011;34(4):729-749. PubMed
- Leeming DJ, et al. Novel serological neo-epitope markers of extracellular matrix proteins for the detection of portal hypertension. Aliment Pharmacol Ther. 2013;38(9):1086-1096. PubMed
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