Changing landscape of optical imaging in skeletal metastases

Abstract

Optical imaging is an emerging strategy for in vitro and in vivo visualization of the molecular mechanisms of cancer over time. An increasing number of optical imaging contrast agents and techniques have been developed in recent years specifically for bone research and skeletal metastases. Visualizing molecular processes in relation to bone remodeling in metastasized cancers provides valuable information for understanding disease mechanisms and monitoring expression of primary molecular targets and therapeutic efficacy. This review is intended to provide an overview of tumor-specific and non-specific contrast agents in the first near-infrared window (NIR-I) window from 650 nm to 950 nm that can be used to study functional and structural aspects of skeletal remodeling of cancer in preclinical animal models. Near-infrared (NIR) optical imaging techniques, specifically NIR spectroscopy and photoacoustic imaging, and their use in skeletal metastases will also be discussed. Perspectives on the promises and challenges facing this exciting field are then given.

Fluorescent Self‐Threaded Peptide Probes for Biological Imaging

“…The high affinity of SF8(DDDDG) 2 for the mineral matrix of exposed bone is consistent with the bone‐seeking behavior of oligo‐aspartate peptides [41, 42, 44] . From a practical perspective, there is substantial ongoing interest in developing fluorescent bone‐seeking probes for both preclinical research and clinical imaging of diseases such as osteoporosis and bone cancer [45, 46] . Most of the literature probes are based on bisphosphonate structures which have the drawback of eliciting strong pharmaceutical activity; [43] thus, there is need for alternative fluorescent probes with different types of bone targeting groups [47, 48] .…”

Preclinical Development of Near-Infrared-Labeled CD38-Targeted Daratumumab for Optical Imaging of CD38 in Multiple Myeloma

“…While retroviral transfection of fluorescent proteins is routinely used to monitor cell and protein expression, these reporter constructs require time-consuming methods for modulation of the native protein and typically use fluorescent proteins in the visible range (400-645 nm) that may not have sufficient brightness and contrast for in vivo imaging [8]. Molecular imaging in the NIR I range (650-950 nm) is an alternative strategy for preclinical evaluation of expression levels in the presence of therapy [17].…”

Fluorescent Self‐Threaded Peptide Probes for Biological Imaging

“…[41,42,44] From ap ractical perspective,t here is substantial ongoing interest in developing fluorescent bone-seeking probes for both preclinical research and clinical imaging of diseases such as osteoporosis and bone cancer. [45,46] Most of the literature probes are based on bisphosphonate structures which have the drawback of eliciting strong pharmaceutical activity; [43] thus,there is need for alternative fluorescent probes with different types of bone targeting groups. [47,48] Thebiocompatibility of oligo-aspartate probes makes them an attractive option;h owever,t he susceptibility of linear L-aspartate sequences to proteolytic…”