In Vitro Engineering of Vascularized Tissue Surrogates

Abstract

In vitro scaling up of bioengineered tissues is known to be limited by diffusion issues, specifically a lack of vasculature. Here, we report a new strategy for preserving cell viability in three-dimensional tissues using cell sheet technology and a perfusion bioreactor having collagen-based microchannels. When triple-layer cardiac cell sheets are incubated within this bioreactor, endothelial cells in the cell sheets migrate to vascularize in the collagen gel, and finally connect with the microchannels. Medium readily flows into the cell sheets through the microchannels and the newly developed capillaries, while the cardiac construct shows simultaneous beating. When additional triple-layer cell sheets are repeatedly layered, new multi-layer construct spontaneously integrates and the resulting construct becomes a vascularized thick tissue. These results confirmed our method to fabricate in vitro vascularized tissue surrogates that overcomes engineered-tissue thickness limitations. The surrogates promise new therapies for damaged organs as well as new in vitro tissue models.

Cell Sheet-Based Tissue Engineering for Fabricating 3-Dimensional Heart Tissues

“…Cocultured endothelial cells migrate into the gel and reach the microchannnels, resulting in a perfusable vascular network. (Reproduced from Sakaguchi K, et al 59 ) host-heart originated blood pulsation might contribute to myocardial tube growth and the hypertrophic response. Functional myocardial tube fabrication using human iPS-derived cardiomyocytes is ongoing both in vivo and in vitro, so further developments may realize a transplantable bioengineered heartassist pump.…”

“…58 In contrast to in vivo femoral tissue, collagen-based vascular beds containing microchannels have also been developed for in vitro vascularized tissue formation (Figure 6). 59 Triple-layer endothelial cell cocultured cardiac cell sheets were also put on the collagen bed and the construct was media-perfused via the microchannels in another bioreactor system using a syringe pump. A significant difference from in vivo tissue usage is the absence of primary cells within the vascular bed; however, cocultured endothelial cells did migrate into the collagen gel and reached the microchannels.…”

Engineering Cardiovascular Regeneration

“…Vascularized cardiac grafts can be produced in vivo by casting hydrogels on an AV-loop [113,114] or multistacking of cell sheets on a vascularized area of the body [115]. For in vitro vascularization, cell sheets have been layered onto a surgically explanted and artificially perfused vascular beds [116•], or constructs are perfused through artificial channels [101,117,118]. Approaches using the biological grafts have the advantage that the vascular bed of the cardiac graft can be anastomosed after transplantation [114,117].…”

“…For in vitro vascularization, cell sheets have been layered onto a surgically explanted and artificially perfused vascular beds [116•], or constructs are perfused through artificial channels [101,117,118]. Approaches using the biological grafts have the advantage that the vascular bed of the cardiac graft can be anastomosed after transplantation [114,117]. Major disadvantages of pre-vascularization are the complexity of the procedures and the concomitant regulatory hurdles.…”

Hollow Fiber Bioreactor Technology for Tissue Engineering Applications

“…In terms of modularity, rHFBs may be designed by small, cellladen modules (i.e., building blocks) to be assembled into larger constructs. This bottom-up approach makes it possible to mimic the heterogeneity of the culture environment and the complexity of some organs that have repetitive modules (5)(6)(7). According to the above-mentioned criteria, we grouped HFBs into cHFBs and rHFBs.…”