Isotope labeled internal standards (ILIS) as a basis for quality control in clinical studies using plasma samples

Area of Science:

• Proteomics
• Biochemistry
• Analytical Chemistry

Background:

• High-quality biofluid samples, like human plasma, are critical for accurate clinical proteomic studies.
• Ensuring sample stability during storage is essential for reliable proteomic data and biobanking.

Purpose of the Study:

• To investigate the stability of human plasma samples under various storage conditions.
• To evaluate the utility of stable isotope-labeled peptides as internal standards for quality control in plasma proteomic analysis.

Main Methods:

• Synthesized three reference peptides (FPA-1, C4A, C3f) with isotopically labeled amino acids.
• Spiked these labeled peptides into human plasma to mimic sample collection.
• Analyzed peptide stability and degradation over two months at -20°C, -80°C, and room temperature using MALDI-MS and nanoLC-ESI-MS.

Main Results:

• All three synthetic peptides remained stable in plasma stored at -20°C and -80°C for two months.
• Distinct proteolytic degradation patterns were observed for the peptides stored at room temperature.
• The study confirmed the quantitative and qualitative integrity of the labeled peptides under optimal storage conditions.

Conclusions:

• Stable isotope-labeled peptides serve as effective internal standards for monitoring human plasma sample quality.
• These standards are crucial for ensuring the reliability of long-term storage and proteomic analysis of plasma biobank samples.
• The findings support the use of these labeled peptides for robust quality control in clinical proteomics.