A Brief Review of Visualization Techniques for Nerve Tissue Engineering Applications

Abstract

In nerve tissue engineering, scaffolds act as carriers for cells and biochemical factors and as constructs providing appropriate mechanical conditions. During nerve regeneration, new tissue grows into the scaffolds, which degrade gradually. To optimize this process, researchers must study and analyze various morphological and structural features of the scaffolds, the ingrowth of nerve tissue, and scaffold degradation. Therefore, visualization of the scaffolds as well as the generated nerve tissue is essential, yet challenging Visualization techniques currently used in nerve tissue engineering include electron microscopy, confocal laser scanning microscopy (CLSM), and micro-computed tomography (micro-CT or μCT). Synchrotron-based micro-CT (SRμCT) is an emerging and promising technique, drawing considerable recent attention. Here, we review typical applications of these visualization techniques in nerve tissue engineering. The promise, feasibility, and challenges of SRμCT as a visualization technique applied to nerve tissue engineering are also discussed.

High-Resolution Imaging for the Analysis and Reconstruction of 3D Microenvironments for Regenerative Medicine: An Application-Focused Review

“…The rapid acquisition speed of state-of-the-art scanners enables the collection of time-dependent data before and after the administration of contrast medium, which enables the visualisation of vascularised tissues and the in-depth analysis of the vascular tree. An important advantage of CT is its lower cost and wider availability compared to other clinical-grade techniques, which can enable faster translation of CT-based applications [ 50 ] ( Figure 2 ).…”

“…Electron microscopy techniques such as scanning electron microscopy (SEM) are widely used for the characterisation of scaffolds in nerve tissue engineering, as they can reveal morphological features, pore size, fibre diameter, and other visual estimates of interconnectivity [ 50 ]. SEM can be combined with focused ion beam lithography to achieve high-resolution cross-sections of neurites and neurons [ 83 ].…”

“…SEM can be combined with focused ion beam lithography to achieve high-resolution cross-sections of neurites and neurons [ 83 ]. Transmission electron microscopy (TEM) can achieve nanometre-scale visualization of nerve tissues and allow for the reconstruction of small, highly detailed sample volumes by tilting ultrathin slices [ 50 ].…”

“…Confocal laser microscopy (CLSM) techniques have been used to obtain high-resolution optical images at selected depths, and have also been applied in in vivo studies, such as in corneal nerve regeneration [ 84 ]. With the use of fluorescent bioactive molecules, drug delivery monitoring can also be achieved [ 50 ]. Secretion of extracellular matrix proteins can also be evaluated with the use of CLSM [ 16 ].…”

“…This is, however, limited due to the low-density properties of the neural tissue, leading to limited distinguishing capability. X-ray staining techniques may be useful, as there are dyes available that can be applied to stain soft tissues or low-density scaffold polymers, such as osmium tetroxide, lyophilic salts, and gold [ 50 , 51 ]. μCT techniques remain complementary to the classic approaches.…”