INTRODUCTION: Biomarker discovery studies seldom report on pre-analytical effects. We used a novel multiplex protein biochip for colorectal cancer screening to investigate effects of different storage temperatures and repeated freeze-thaw cycles. METHODS: This biochip, composed of CEA, IL-8, VEGF, M-CSF, S100A11, C3adesArg, CD26, and CRP, was applied to twenty highly standardized preserved serum samples. RESULTS: Aliquot comparison of long-term storage at -80°C (n=20) versus -170°C (n=20) did not show significant differences for any of the eight markers. In contrast, three freeze-thaw cycles (3 × 20 aliquots) detected changes in the serum level for all markers (p<0.05) but S100A11 and CD26: levels of CEA, IL-8, C3adesArg, and CRP increased, while VEGF and M-CSF levels decreased. However, applying diagnostic thresholds for CEA, IL-8, and CRP revealed that freeze-thaw cycles did not affect diagnostic performance. In contrast, analysis of samples stored at -80°C compared to -170°C failed to detect one out of three detectable malignancies. CONCLUSION: We conclude that three freeze-thaw cycles modulated serum marker levels significantly, but do not compromise biochip diagnostic performance. For our marker panel, serum preservation at -80°C seems comparable to -170°C; however, storage at -80°C could lead to misdiagnosis. Our findings emphasize the need for standardized sample collection, processing, storage, and reporting.
INTRODUCTION: Biomarker discovery studies seldom report on pre-analytical effects. We used a novel multiplex protein biochip for colorectal cancer screening to investigate effects of different storage temperatures and repeated freeze-thaw cycles. METHODS: This biochip, composed of CEA, IL-8, VEGF, M-CSF, S100A11, C3adesArg, CD26, and CRP, was applied to twenty highly standardized preserved serum samples. RESULTS: Aliquot comparison of long-term storage at -80°C (n=20) versus -170°C (n=20) did not show significant differences for any of the eight markers. In contrast, three freeze-thaw cycles (3 × 20 aliquots) detected changes in the serum level for all markers (p<0.05) but S100A11 and CD26: levels of CEA, IL-8, C3adesArg, and CRP increased, while VEGF and M-CSF levels decreased. However, applying diagnostic thresholds for CEA, IL-8, and CRP revealed that freeze-thaw cycles did not affect diagnostic performance. In contrast, analysis of samples stored at -80°C compared to -170°C failed to detect one out of three detectable malignancies. CONCLUSION: We conclude that three freeze-thaw cycles modulated serum marker levels significantly, but do not compromise biochip diagnostic performance. For our marker panel, serum preservation at -80°C seems comparable to -170°C; however, storage at -80°C could lead to misdiagnosis. Our findings emphasize the need for standardized sample collection, processing, storage, and reporting.
Authors: Dominik Lermen; Frederik Gwinner; Martina Bartel-Steinbach; Sabine C Mueller; Jens K Habermann; Matharoo-Ball Balwir; Elke Smits; Ana Virgolino; Ulrike Fiddicke; Marika Berglund; Agneta Åkesson; Anna Bergstrom; Karin Leander; Milena Horvat; Janja Snoj Tratnik; Manuel Posada de la Paz; Argelia Castaño Calvo; Marta Esteban López; Hagen von Briesen; Heiko Zimmermann; Marike Kolossa-Gehring Journal: Biopreserv Biobank Date: 2020-04 Impact factor: 2.300