PB0734 - Visualization of Gliomas with Clot-binding Peptides

Monday, July 11, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Carolin Wolter, MSc

PhD Student
Institute of Clinical Hemostaseology and Transfusion Medicine, Saarland University School of Medicine and Saarland University Medical Center
Homburg, Saarland, Germany

Co-Author(s)

LK

Lynn M. Knowles

Research Instructor
Institute of Clinical Hemostaseology and Transfusion Medicine, Saarland University School of Medicine and Saarland University Medical Center
Homburg, Saarland, Germany
SL

Stefan Linsler

Deputy Director
Departement of Neurosurgery
Homburg, Saarland, Germany
SM

Simon Müller

Consultant
Departement of Neurosurgery
Homburg, Saarland, Germany
MJ

Martin Jung

Professor
Medical Biochemistry and Molecular Biology
Homburg, Saarland, Germany
HE

Hermann Eichler

Professor of Transfusion Medicine and Haemostaseology
Institute of Clinical Haemostaseology and Transfusion Medicine, University and University Hospital of the Saarland, Homburg, Germany
Homburg, Saarland, Germany
Jan Pilch, MD

Assistant Professor
Institute of Clinical Hemostaseology and Transfusion Medicine, Saarland University School of Medicine and Saarland University Medical Center
Homburg, Saarland, Germany

Background: Glioblastoma (GBM) is a highly aggressive brain tumor characterized by necrosis, hemorrhage and thrombosis. The outcome of GBM correlates with the extent of surgical tumor removal.

Aims: To test if the formation of a fibrin-rich extracellular matrix provides binding sites for clot-binding peptides that support fluorescent-guided recognition and surgical removal of astrocytomas.

Methods: We analyzed fibrin formation in astrocytoma samples from patients using immunohistochemistry. To assess the uptake of clot-binding peptides into brain tumors, we injected fluorescein-labeled peptides intravenously in GBM-bearing mice. Two-four hours later the brain and control organs were isolated and tissue sections were evaluated by fluorescence microscopy. In addition, we assessed peptide uptake into intracranial brain tumors in intact mice using a fluorescence endoscope in situ. The role of clotting was tested in GL-261 glioblastomas grown in transgenic hemophilia A mice.

Results: We demonstrate a marked upregulation of clot formation in the interstitial spaces of astrocytoma patients while tumor-free brain is essentially devoid of fibrin. Five different peptides with affinity for clot or brain injury (CLT1, CLT1-IK, CLT2, CREKA, CAQK) were injected into GBM-bearing mice to visualize fibrin accumulation. Subsequent analysis showed the strongest fluorescence after injection of CLT1 while two unspecific control peptides did not generate any fluorescence. The fluorescent label of CLT1 was specific for clot in brain tumor tissue whereas no fluorescence was detectable in tumor tissue in absence of clotting activity or in normal brain tissue. Using fluorescence endoscopy, specific fluorescence by the clot-binding peptide was detectable in brain tumors of intact mice in situ.

Conclusion(s): Our data demonstrate stage-dependent fibrin deposition in astrocytomas that can be visualized with the clot-binding peptide CLT1 in vivo. Moreover, our data suggest that CLT1 can improve fluorescent-guided detection and removal of astrocytoma in situ.