Abstract
The survival and function of thick tissue engineered implanted constructs depends on pre-existing, embedded, functional, vascular-like structures that are able to integrate with the host vasculature. Bioprinting was employed to build perfusable vascular-like networks within thick constructs. However, the improvement of oxygen transportation facilitated by these vascular-like networks was directly quantified. Using an optical fiber oxygen sensor, we measured the oxygen content at different positions within 3D bioprinted constructs with and without perfusable microchannel networks. Perfusion was found to play an essential role in maintaining relatively high oxygen content in cell-laden constructs and, consequently, high cell viability. The concentration of oxygen changes following switching on and off the perfusion. Oxygen concentration depletes quickly after pausing perfusion but recovers rapidly after resuming the perfusion. The quantification of oxygen levels within cell-laden hydrogel constructs could provide insight into channel network design and cellular responses.
Highlights
Tissue engineering holds promise for the production of replacement tissues and organs to address the current shortage in donated organs [1,2]
Our findings show that microchannels alone are not sufficient to maintain sufficient oxygen levels and that perfusion is key for sustaining a high oxygen concentration and cell viability within the constructs
Previous results showed that Si-HPMC hydrogel starts crosslinking after pH neutralization, gelation point occurs at 30 min [23], and crosslinking continues at room temperature over several hours
Summary
Various approaches, including angiogenesis induction by growth factors [8] and engineered vascular-like perfusable networks [9,10,11], have been developed to address the challenge of vascularization Growth factors, such as vascular endothelial growth factor(VEGF) and basic fibroblast growth factor (bFGF), stimulate the recruitment of endothelial cells [12] and have been shown to improve vascularization after implantation of tissue engineered constructs [8]. This strategy requires a relatively long time to establish a fully functional vasculature. The cells in the constructs rely on the diffusion of oxygen and nutrients from the host, which can comprise
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