Direct 3D bioprinting of perfusable vascular constructs using a blend bioink

Abstract

Despite the significant technological advancement in tissue engineering, challenges still exist towards the development of complex and fully functional tissue constructs that mimic their natural counterparts. To address these challenges, bioprinting has emerged as an enabling technology to create highly organized three-dimensional (3D) vascular networks within engineered tissue constructs to promote the transport of oxygen, nutrients, and waste products, which can hardly be realized using conventional microfabrication techniques. Here, we report the development of a versatile 3D bioprinting strategy that employs biomimetic biomaterials and an advanced extrusion system to deposit perfusable vascular structures with highly ordered arrangements in a single-step process. In particular, a specially designed cell-responsive bioink consisting of gelatin methacryloyl (GelMA), sodium alginate, and 4-arm poly(-ethylene glycol)-tetra-acrylate (PEGTA) was used in combination with a multilayered coaxial extrusion system to achieve direct 3D bioprinting. This blend bioink could be first ionically crosslinked by calcium ions followed by covalent photocrosslinking of GelMA and PEGTA to form stable constructs. The rheological properties of the bioink and the mechanical strengths of the resulting constructs were tuned by the introduction of PEGTA, which facilitated the precise deposition of complex multilayered 3D perfusable hollow tubes. This blend bioink also displayed favorable biological characteristics that supported the spreading and proliferation of encapsulated endothelial and stem cells in the bioprinted constructs, leading to the formation of biologically relevant, highly organized, perfusable vessels. These characteristics make this novel 3D bioprinting technique superior to conventional microfabrication or sacrificial templating approaches for fabrication of the perfusable vasculature. We envision that our advanced bioprinting technology and bioink formulation may also have significant potentials in engineering large-scale vascularized tissue constructs towards applications in organ transplantation and repair.

Tissue Engineered Bio‐Blood‐Vessels Constructed Using a Tissue‐Specific Bioink and 3D Coaxial Cell Printing Technique: A Novel Therapy for Ischemic Disease

“…[23] To the contrary, hydrogel tubes produced using 3D coaxial cell printing method had never realized endothelialization in the reported studies. [7,8] This observation further substantiates the superiority of our hybrid bioink compared to other ever-applied materials in terms of leveraging printability and biofunctionality for vascular tissue engineering.…”

“…Therefore, alginate-based hydrogel is widely used due to the rapid ionic crosslinking via calcic treatment. [7,8] However, the deficiency of binding sites for cell attachment and migration in alginate drastically impairs activities of entrapped cells. Hence, it is necessary to seek an endothelial-inspiring material for this engineering technique.…”

3D printing of hydrogel composite systems: Recent advances in technology for tissue engineering

“…To achieve this goal, double-nozzle assembling method was adapted to 3D-print vascular for liver by Li's group [130] . Li fabricated gelatin/alginate/chitosan (GAC) hydrogel composites combined with adipose-derived stromal cells (ADSC) and printed them to form vascular networks.…”

“…They mixed gelatin methacryloyl (GelMA) and 4-arm poly(ethylene glycol)-tetra-acrylate (PEGTA) for fixing the morphologies of the constructs permanently and sodium alginate for maintaining the shape by fast Figure 11. Various strategies of constructing vascular system (A) using a multiple coaxial nozzle with alginate, GelMA, and 4-arm PEGTA (reproduced with permission from [131]. Copyright 2016, Elsevier Ltd), (B) bioprinting layer-by-layer with collagen, fibrin-cell mixture, and sacrificial gelatin, (reproduced with permission from [140].…”

Current developments in 3D bioprinting for tissue engineering

“…However, the real challenge of bioprinting lies in the creation of larger, vascularized tissues [7]. Some research shows printing with hollow fibres [58], which can be lined with endothelial cells, to create 3D constructs that are completely perfusable [59]. Another method to create perfusable channels in constructs is by printing with fugitive inks as discussed previously.…”