The integration of 3-D cell printing and mesoscopic fluorescence molecular tomography of vascular constructs within thick hydrogel scaffolds

Abstract

Developing methods that provide adequate vascular perfusion is an important step toward engineering large functional tissues. Meanwhile, an imaging modality to assess the three-dimensional (3-D) structures and functions of the vascular channels is lacking for thick matrices (>2~3mm). Herein, we report on an original approach to construct and image 3-D dynamically perfused vascular structures in thick hydrogel scaffolds. In this work, we integrated a robotic 3-D cell-printing technology with a mesoscopic fluorescence molecular tomography imaging system, and demonstrated the capability of the platform to construct perfused collagen scaffolds with endothelial lining and to image both the fluid flow and fluorescent-labeled living endothelial cells at high-frame rates, with high sensitivity and accuracy. These results establish the potential of integrating both 3-D cell-printing and fluorescence mesoscopic imaging for functional and molecular studies in complex tissue engineered tissues.

Mesoscopic fluorescence molecular tomography of reporter genes in bioprinted thick tissue

“…Our results, as well as the previous studies, 2 show the potential of MFMT as a powerful tool for tissue engineering applications. We believe that MFMT will have an important role to localize and monitor live fluorescent cells in thick tissue.…”

“…Three-dimensional (3-D) bioprinting technology is capable of manufacturing thick tissues as well as printing vasculatures. 2 The resulting tissues are, however, thick (∼3 mm), turbid, and hosted inside sealed bioreactors. Hence, it is difficult to employ traditional microscopic imaging methods to assess structure and function of the whole sample.…”

“…2 MFMT is well suited for in-vitro tomographic imaging, 2 as well as for ex vivo 12 and clinical imaging scenarios. 13 Furthermore, it can be fused with other traditional optical imaging modalities such as OCT. 11 One key advantage of MFMT is its ability to image a variety of fluorescent probes.…”

“…The optical setup is similar to the one in Zhao et al 2 We have replaced the lenses with antireflective-coated achromatic ones and added one spectral channel. We have used emission filters (XB97/560BP10, Omega Optics; FF01-650/60-25, and FF01-700/13-25, Semrock) for corresponding Diode Laser source of 488, 589, and 658 nm, respectively.…”

“…The optical properties, used to compute the Jacobian, were set at μ s ¼ 5 mm −1 , μ a ¼ 0.002 mm −1 , and g ¼ 0.9. These values were selected based on previous studies 2 and reported values for collagen in the literature. Note that the optical properties were similar for all wavelengths investigated herein.…”