Speaker
Description
Introduction:
On-chip vascular microfluidic models provide powerful platforms for studying vasculature and its diseases in vitro. These models enable focused investigation of specific vascular layers, such as the endothelium, and the influence of hemodynamics on it. While traditional plastics or glass-based fabrication allows for defined microchannel architecture, its inherent stiffness and low permeability limit biological applications. Thus, hydrogels are gaining interest. Specifically, Gelatin Methacryloyl (GelMA) and Collagen Methacryloyl (ColMA) are attractive due to their porosity, tunable mechanical properties, and inherent bioactivity, closely mimicking the native extracellular matrix (ECM). Here, we present a method combining 3D printing and casting to create hydrogel microfluidic chips with smooth, cylindrical channels.
Methods:
GelMA [1] and ColMA [2] were synthesized according to published protocols. Hydrogels were prepared using 5, 10, and 15% of GelMa and 0.5, 1, and 1.5% ColMa. Compression and swelling tests evaluated physical properties. Porosity was assessed using Scanning Electron Microscopy. Endothelial cell (MS1 and HUVEC) viability on these materials was analyzed. For microfluidic chip preparation, a frame defining the outer geometry was fabricated using Stereolithography printing with a biocompatible resin. Stainless-steel needles (0.8 mm diameter, 3 cm length) were inserted into the frame, and after casting and photocrosslinking the hydrogel, the needles were carefully removed to form smooth, cylindrical lumens. The lumens were then seeded with endothelial cells, which were subjected to pathophysiology-relevant flow.
Results:
Compared to single-component hydrogels, the 15% GelMA / 1.5% ColMA hydrogel exhibited superior mechanical properties, including a higher compressive modulus and lower swelling. The porosity of the hydrogels correlated with the dry content of the gel. All tested hydrogels provided reasonable support for endothelial cells. Formulations with higher solids and 1% ColMA better supported long-term cell culture. The method of chip fabrication produced an optically transparent device, having microchannels with smooth, cylindrical lumens (800 µm diameter; surface roughness ≤ 1 µm). Channels remained stable under shear stresses up to about 70 Pa. Endothelial cells seeded into the channels responded to flow conditions by changes in elongation and orientation.
Discussion:
Our method generated transparent GelMA/ColMA composite hydrogels. Methacrylation enabled tunable mechanical properties; increased ColMa and solids, enhanced the compressive modulus, and reduced swelling. This provided crucial stability, essential for maintaining channel integrity under perfusion in the hydrogel chip. Indeed, the channels with smooth, cylindrical lumens showed excellent stability up to about 70 Pa of shear stress. This platform enables investigation of endothelial mechanobiology under defined pathophysiological conditions.
Acknowledgment:
The study was supported by Ministry of Health of the Czech Republic (grants nr. NW24-08-00064 and NU22-08-00124), and MEDITECH - Centre for multidisciplinary research in cardiovascular medicine (grant nr. CZ.02.01.01/00/23_021/0009171) and Faculty of Medicine of Masaryk University (nr. MUNI/A/1644/2024).
References
[1] N. Annabi et al., “Hydrogel-coated microfluidic channels for cardiomyocyte culture,” Lab Chip, vol. 13, no. 18, p. 3569, 2013.
[2] S. M. Ali, N. Y. Patrawalla, N. S. Kajave, A. B. Brown, and V. Kishore, “Species-Based Differences in Mechanical Properties, Cytocompatibility, and Printability of Methacrylated Collagen Hydrogels,” Biomacromolecules, vol. 23, no. 12, pp. 5137–5147, Dec. 2022.
74734112855