Rapid casting of patterned vascular networks for perfusable engineered three-dimensional tissues

Abstract

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core [1]. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture [2–4]. Here, we 3D printed rigid filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks which could be lined with endothelial cells and perfused with blood under high-pressure pulsatile flow. Because this simple vascular casting approach allows independent control of network geometry, endothelialization, and extravascular tissue, it is compatible with a wide variety of cell types, synthetic and natural extracellular matrices (ECMs), and crosslinking strategies. We also demonstrated that the perfused vascular channels sustained the metabolic function of primary rat hepatocytes in engineered tissue constructs that otherwise exhibited suppressed function in their core.

Hydrogel-based microfluidics for vascular tissue engineering

“…There are a number of studies that utilized fibrin gel for the creation of micro vessel tubes [34][35][36]. The proof of principle described in this work utilized a similar approach for the formation of a single fluidic channel within the cell laden PEGylated fibrin gel.…”

“…Here we first focused on the evaluation of optimum gel properties for induction of a cellular lumenalized network by co-culture of vasculogenic cells. However, the principle of a sacrificial material interconnected capillary network formation based on utilization of gelatin [37] or sugar [35] is certainly applicable to the approach described in this paper. Using a combination of photolithography and soft lithography methods, it should be possible to fabricate complex interconnected microchannel networks from a sacrificial material and apply it for embedding within cell laden PEGylated fibrin gels.…”

3D bioprinting for cell culture and tissue fabrication

“…The results illustrated that vessel-like construct with complex geometry could be successfully fabricated by 3D bioprinting technique [35]. Miller et al [36] constructed a rigid filament network using endothelial cells encapsulated within carbohydrate glass (Fig. 1a).…”

“…1a). In the circumstance, the bioprinted scaffold was perfused with blood under highpressure pulsating flow, and the cells retained a high vitality in the vessel-like architecture [36].…”

“…It has been observed many years ago that "…gels seeded with cells have been limited by the fact that the resultant cell densities per unit volume that can be achieved are much lower than those observed in vivo…" [118]. Until now however, maintaining and improving cell density in tissue construct is still an unsolved problem [119]. When planning for a tissue or organoid fabrication, we should figure out how to organize multiple cell types into spatial arrangement where their original function can be achieved in the post-printing tissue maturation period.…”