Intraoperative visualization of nerves using a myelin protein-zero specific fluorescent tracer

Abstract

Background Surgically induced nerve damage is a common but debilitating side effect in oncological surgery. With the aim to use fluorescence guidance to enable nerve-sparing interventions in future surgery, a fluorescent tracer was developed that specifically targets myelin protein zero (P0). Results Truncated homotypic P0 protein-based peptide sequences were C-terminally functionalized with the far-red cyanine dye Cy5. The lead compound Cy5-P0101–125 was selected after initial solubility, (photo)physical and in vitro evaluation (including P0-blocking experiments). Cy5-P0101–125 (KD = 105 ± 17 nM) allowed in vitro and ex vivo P0-related staining. Furthermore, Cy5-P0101–125 enabled in vivo fluorescence imaging of the Sciatic nerve in mice after local intravenous (i.v.) administration and showed compatibility with a clinical fluorescence laparoscope during evaluation in a porcine model undergoing robot-assisted surgery. Biodistribution data revealed that i.v. administered [111In]In-DTPA-P0101–125 does not enter the central nervous system (CNS). Conclusion P0101–125 has proven to be a potent nerve-specific agent that is able to target P0/myelin under in vitro, ex vivo, and in vivo conditions without posing a threat for CNS-related toxicity.

Fluorescence imaging of peripheral nerve function and structure

“…1 Key achievements in the development of nerve-labeling fluorescent agents. This timeline includes the significant biomedical tracing with HRP, 68 neuron tracing with virus, 39 neuron tracing with WGA, 74 neuron tracing with CTB; 52 neuron tracing with BDA, 63 neuron imaging with anti-Agrin, 94 neuron tracing with ICG in optical nerve, 124 neuron imaging with BMB, 98 neuron imaging with Coumarin, 111 neuron imaging with GE3082, 104 neuron imaging with Cy5-NP41, 118 neuron imaging with oxazine4, 107 neuron imaging with Hsp1a, 123 neuron imaging with myelin protein 0, 113 neuron imaging with LGW01-08, 108 neuron imaging with AIEgens; 114 mainly including viruses, bacterial toxins, phytoagglutinins, and phytoenzymes. Local injection administration is frequently employed for delivering these tracers as they exhibit limited ability to traverse the blood-nerve barrier (BBB) but can be readily absorbed by nerve endings in the mammalian muscle and subsequently conveyed through the axons within the nerve.…”

“…P0 is crucial for maintaining the integrity of the axons as well as the proper spiral, compaction, and maintenance of the peripheral nerve's myelin sheath. By attaching Cy5 to the C-terminus of the P0 peptide sequence, Tessa Buckle et al created the neural tracer peptide Cy5-P0101-125 in 2021, which was designed to target myelin protein-0 (P0) 113 [Fig. 4E].…”

“…Fig.1Key achievements in the development of nerve-labeling fluorescent agents. This timeline includes the significant biomedical tracing with HRP,68 neuron tracing with virus,39 neuron tracing with WGA,74 neuron tracing with CTB; 52 neuron tracing with BDA,63 neuron imaging with anti-Agrin,94 neuron tracing with ICG in optical nerve,124 neuron imaging with BMB,98 neuron imaging with Coumarin,111 neuron imaging with GE3082,104 neuron imaging with Cy5-NP41,118 neuron imaging with oxazine4,107 neuron imaging with Hsp1a,123 neuron imaging with myelin protein 0,113 neuron imaging with LGW01-08,108 neuron imaging with AIEgens;114 Images reproduced with permission from ref. 68.…”

Rapid Peripheral Nerve Imaging by Fluorescent Polymer Dots for Minimizing the Risk of Intraoperative Nerve Injury

“…Fluorescence imaging helps surgeons navigate intraoperatively by allowing direct and real-time visualization, and has been used in the detection and treatment of many diseases. [12,13] In addition, Fluorescence imaging based on specific probes shows great promise in distinguishing normal and pathological structures during surgical procedures including nerves. [14,15] A number of fluorescent probes for peripheral nerve imaging have been developed.…”

“…However, these techniques lack specificity, resolution, and wide‐field imaging functionality, making real‐time nerve detection difficult. Fluorescence imaging helps surgeons navigate intraoperatively by allowing direct and real‐time visualization, and has been used in the detection and treatment of many diseases [12,13] . In addition, Fluorescence imaging based on specific probes shows great promise in distinguishing normal and pathological structures during surgical procedures including nerves [14,15] …”