RSNA: Peptides show promise in designing molecular ultrasound contrast agents

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Knottin peptides may be a promising platform for designing novel contrast agents for molecular ultrasound imaging of tumor angiogenesis, according to a study presented at the annual Radiological Society of North America (RSNA) meeting.

Juergen K. Willmann, MD, assistant professor at Stanford University School of Medicine in Stanford, Calif., said, “The purpose of the study was to develop and test a novel small peptide-based ultrasound contrast agent for in vivo molecular ultrasound imaging of integrin expression on tumor endothelial cells.”

Knottin integrin is a peptide integrated into a polypeptide scaffold. The researchers designed a molecular ultrasound imaging contrast agent by attaching knottin integrin onto the shell of perfluorocarbon-filled microbubbles (MBKnottinIntegrin).

A scrambled knottin peptide was used to create control microbubbles by the investigators.

In the study, in vivo imaging signals of contrast-enhanced ultrasound using microbubbles were quantified in 49 mice bearing human ovarian adenocarcinoma xenograft tumors.

Willmann said that the control microbubbles adhered less to endothelial cells (0.17) than MBKnottinIntegrin (0.47). When the researchers blocked the integrin receptors, MBKnottinIntegrin’s imaging signal significantly dropped by 64 percent.

“The study lays the foundation for developing next-generation contrast microbubbles using a versatile peptide platform, which may facilitate the clinical translation of molecular ultrasound imaging,” Willmann predicts.