In recent years, many advances have been made in fabricating engineered tissues; however,  these tissues cannot survive without proper internal transportation systems for nutrients, oxygen, waste, etc. This study investigated Extrusion and Digital Light Processing (DLP) methods for three-dimensional (3D) bioprinting techniques and their effectiveness in designing vascular systems that mimic the organotypic size and distribution of microvasculature. For this effort, vasculature was modeled in three types of tissues: cardiac, hepatic, and renal. To model each branching generation formed during vascular development, the Scaling Law of Blood Flow Resistance was combined with the equation for crown volume (a derivation stemming from the average branching ratio). We developed a simple MATLAB script in which the initial vascular parameters are input, and the diameter, length, and volume of blood vessels at each branching level is calculated up to a desired blood volume of the organ. The input parameters are the physical dimensions of the most proximal stem (main starting vessel for the organ) and the total blood volume per unit of area of tissue. With these calculated data, computer-aided design (CAD) models of the vasculature were created and physical models were bioprinted by optimizing both process parameters and bioink chemistry. Future efforts will investigate the integration of resident cell populations during the bioprinting process to produce microscale organ models. If these 3D printing design techniques and process parameters successfully produce vascularized tissues constructs, our results will highlight new methods for more uniform engineered tissue products for cardiac and vascularized regenerative therapies.

Designing and 3D Bioprinting of Organotypic Vascularized Tissues

ACS Fall 2021

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