3D Bioprinted GelMA Based Models for the Study of Trophoblast Cell Invasion

Abstract

Bioprinting is an emerging and promising technique for fabricating 3D cell-laden constructs for various biomedical applications. In this paper, we employed 3D bioprinted GelMA-based models to investigate the trophoblast cell invasion phenomenon, enabling studies of key placental functions. Initially, a set of optimized material and process parameters including GelMA concentration, UV crosslinking time and printing configuration were identified by systematic, parametric study. Following this, a multiple-ring model (2D multi-ring model) was tested with the HTR-8/SVneo trophoblast cell line to measure cell movement under the influence of EGF (chemoattractant) gradients. In the multi-ring model, the cell front used as a cell invasion indicator moves at a rate of 85 ± 33 µm/day with an EGF gradient of 16 µM. However, the rate was dramatically reduced to 13 ± 5 µm/day, when the multi-ring model was covered with a GelMA layer to constrain cells within the 3D environment (3D multi-ring model). Due to the geometric and the functional limitations of multi-ring model, a multi-strip model (2D multi-strip model) was developed to investigate cell movement in the presence and absence of the EGF chemoattractant. The results show that in the absence of an overlying cell-free layer of GelMA, movement of the cell front shows no significant differences between control and EGF-stimulated rates, due to the combination of migration and proliferation at high cell density (6 × 106 cells/ml) near the GelMA surface. When the model was covered by a layer of GelMA (3D multi-strip model) and migration was excluded, EGF-stimulated cells showed an invasion rate of 21 ± 3 µm/day compared to the rate for unstimulated cells, of 5 ± 4 µm/day. The novel features described in this report advance the use of the 3D bioprinted placental model as a practical tool for not only measurement of trophoblast invasion but also the interaction of invading cells with other tissue elements.

Rheological Properties of Coordinated Physical Gelation and Chemical Crosslinking in Gelatin Methacryloyl (GelMA) Hydrogels

“…We selected 4 wt% GelMA because concentrations of 5 wt% or less, while difficult to bioprint due to low viscosity, demonstrate improved cellular viability, sustained proliferation, and exhibit modulus ranging from 0.25 to 1.5 kPa. [ 71–75 ] In our experiments, scaffolds polymerized at 4 °C possessed coordinated physical gelation and chemical crosslinking, resulting in a stiffer scaffold. HDFns seeded on coordinated gelation and crosslinked scaffold demonstrated an elongated morphology ( Figure 6 a).…”

The Photoinitiator Lithium Phenyl (2,4,6-Trimethylbenzoyl) Phosphinate with Exposure to 405 nm Light Is Cytotoxic to Mammalian Cells but Not Mutagenic in Bacterial Reverse Mutation Assays

“…For example, underexposure would result in imprecise control of the mechanical properties and an increase in the concentration of unreacted monomer, while overexposure would expose cells to additional phototoxic effects while not significantly affecting the mechanical properties. Multiple studies report photopolymer tissue engineering constructs with low cytotoxicity, and/or the ability of cells to proliferate within the construct after printing [ 28 , 36 , 37 ]. The success of this technique is contrary to the assumption that free-radical generating photoinitiators produce toxic effects, including genotoxicity, from reactive oxygen species [ 14 , 38 ].…”

3D-Printed Gelatin Methacryloyl-Based Scaffolds with Potential Application in Tissue Engineering

“…Moreover, gelatin resembles the chemical structure and biological functions of collagen in the native ECM. Due to these characteristics, gelatin is considered an ideal material that could emulate the natural structure of the ECM [ 14 , 15 , 16 ]. For example, gelatin was used to design and fabricate nerve guidance conduits (NGCs) to repair large gap nerve injuries [ 17 ].…”