Scanning-fiber-based imaging method for tissue engineering

Abstract

A scanning-fiber-based method developed for imaging bioengineered tissue constructs such as synthetic carotid arteries is reported. Our approach is based on directly embedding one or more hollow-core silica fibers within the tissue scaffold to function as micro-imaging channels (MIC). The imaging process is carried out by translating and rotating an angle-polished fiber micro-mirror within the MIC to scan excitation light across the tissue scaffold. The locally emitted fluorescent signals are captured using an electron multiplying CCD camera and then mapped into fluorophore distributions according to fiber micro-mirror positions. Using an optical phantom composed of fluorescent microspheres, tissue scaffolds, and porcine skin, we demonstrated single-cell-level imaging resolution (20 to 30 μm) at an imaging depth that exceeds the photon transport mean free path by one order of magnitude. This result suggests that the imaging depth is no longer constrained by photon scattering, but rather by the requirement that the fluorophore signal overcomes the background "noise" generated by processes such as scaffold autofluorescence. Finally, we demonstrated the compatibility of our imaging method with tissue engineering by visualizing endothelial cells labeled with green fluorescent protein through a ∼500 μm thick and highly scattering electrospun scaffold.

Dynamic, Nondestructive Imaging of a Bioengineered Vascular Graft Endothelium

“…The necessity to monitor vascular graft endothelialization and maturation in real time during preconditioning has led our group to develop a fiber optic based (FOB) imaging system to accomplish this task [21], [22]. The imaging system is designed to noninvasively assess the graft endothelium without disturbing the graft during preconditioning in a bioreactor.…”

The role of endothelial cells in myofiber differentiation and the vascularization and innervation of bioengineered muscle tissue in vivo

“…microscopy). We recently published a study that demonstrated the development of a novel imaging system utilizing miniature fiber optical devices for nondestructive, single-cell-level resolution imaging of bioengineered tissue constructs [47,48]. The current study demonstrates the ability to positively identify implanted GFP-MPCs and -ECs after 8 weeks implantation in vivo , a sufficiently long enough time to follow many regenerative processes.…”

“…Subsequently, we demonstrated the ability to image the interactions and differentiation capabilities of 3 fluorescently labeled cell types: MPCs, ECs and PCs, in real time in vitro , demonstrating a biological fluorescent imaging application. Combining the method developed here with the fiber-optic-based imaging modality described before [47,48], it will be possible to document tissue development and monitor the dynamic interplay between multiple cells types in vivo , in real-time, and with single-cell-level resolution. Such a technology may serve as a potent platform for testing the effects of different biological or pharmacological agents on tissue regeneration.…”

Optical fiber based imaging of bioengineered tissue construct

“…To realize the full potential of fluorescent proteins, however, one needs to go beyond the current framework for cell and tissue analysis, which is based on invasive tools such as immunohistochemistry and cell extraction for molecular assays such as Western blotting and quantitative Polymerase Chain Reaction (qPCR) [3,4]. Our imaging system allows non-invasive monitoring of bioengineered tissue constructs, through turbid and scattering media, while providing cell size (15-20 µm) resolution [5,6]. Additionally, the imaging system possesses a large working distance of 8 cm.…”