Research Assistant Professor Lehigh University, United States
Introduction: Human uterine myometrial tissue is composed of three layers in distinct patterns and orientations. While tissue pattern integrity is essential for all dynamic tissue structures to remodel and regenerate, very few existing in-vitro models of healthy uterine myometrium are designed using native healthy myometrium tissue as architectural blueprints. The healthy myometrium extracellular matrix (ECM) tissue pattern has been described as a basketweave pattern, with ECM alignment parallel to uterine smooth muscle cell fiber patterns. ECM disorganization results in unfavorable disease states such as the development of uterine fibroids. Herein, we report the intentional computer-aided design (CAD) and preliminary extrusion of the inner, middle and outer uterine myometrial layers for three-dimensional (3D) bioprinting gynecological applications.
Materials and
Methods: Three-dimensional bioprinting experiments were performed with a RegenHu 200 bioprinter (RegenHu, Switzerland), using a pneumatic-driven extrusion printhead. A conical nozzle with an inner diameter of 0.25 mm (Nordson EFD, USA) was used to print Pluronic 127 ink at an extrusion pressure of 275 kPa at 23℃. G-codes for three myometrial-like layers were generated using BioCAD and Shaper software (RegenHu, Switzerland). Bioink filaments were programmed to have a maximum strand distance of 1.00 mm filament spacing. Optimized design parameters for inner, middle and outer myometrial layers included the design shape, perimeter, infill, layer height, printing speed and layer strand height.
Results, Conclusions, and Discussions:
Results: Favorable construct shapes modeling the inner, middle and outer human myometerial layers were semicircular, sinusoidal and longitudinal respectively. Optimal design parameters resulting in the extrusion of continuous filament were an "online" perimeter strand placement with an infill spacing of 0.5mm. Each layer (minimum three continuous filaments/layer) consisted of a single layer height of 0.250 mm for a total combined height of 0.750mm when printed sequentially (inner, middle, outer).
Conclusions: Using pluronic-127 as an initial proof-of-concept printing media, we achieved the design and extrusion of continuous filament for three distinct myometrial layers optimized for metabolic waste, nutrient exchange and myometrial cell signaling (0.500 mm spacing). Discussions: We expect our bioprinted ECM myometrium templates will facilitate human uterine cell patterned tissue regeneration. As such, the development of printable biomimetic 3D tissue models will result in a novel platform to efficiently screen myometrial tissue reparative therapeutics and elucidate the underlying cellular mechanisms of action causing disruption of healthy myometrium tissue.
Acknowledgements (Optional): We would like to kindly acknowledge Dr. Yun Chen at Johns Hopkins University for initial training on the RegenHU 200 3D Bioprinter.
