Development of a novel micro-ablation system to realise micrometric and well-defined hydrogel structures for tissue engineering applications

Abstract

Purpose\ud – This paper aims to develop a novel micro-ablation system to realise micrometric and well-defined hydrogel structures. To engineer a tissue it is necessary to evaluate several aspects, such as cell-cell and cell-substrate interactions, its micro-architecture and mechanical stimuli that act on it. For this reason, it is important to fabricate a substrate which presents a microtopology similar to natural tissue and has chemical and mechanical properties able to promote cell functions. In this paper, well-defined hydrogel structures embedding cells were microfabricated using a purposely developed technique, micro-laser ablation, based on a thulium laser. Its working parameters (laser power emission, stepper motor velocity) were optimised to produce shaded “serpentine” pattern on a hydrogel film.\ud \ud Design/methodology/approach\ud – In this study, initially, swelling/contraction tests on agarose and alginate hydrogel in different solutions of main components of cell culture medium were performed and were compared with the MECpH model. This comparison matched with good approximation experimental measurements. Once known how hydrogel changed its topology, microstructures with a well-defined topology were realised using a purposely developed micro-laser ablation system design. S5Y5 neuroblastoma cell lines were embedded in hydrogel matrix and the whole structure was ablated with a laser microfabrication system. The cells did not show damages due to mechanical stress present in the hydrogel matrix and to thermal increase induced by the laser beam.\ud \ud Findings\ud – The hydrogel structure is able to reproduce extracellular matrix. Initially, the hydrogel swelling/contraction in different solutions, containing the main components of the most common cell culture media, was analysed. This analysis is important to evaluate if cell culture environment could alter microtopology of realised structures. Then, the same topology was realised on hydrogel film embedding neuronal cells and the cells did not show damages due to mechanical stress present in the hydrogel matrix and to thermal increase induced by the laser beam. The interesting obtained results could be useful to realise well-defined microfabricated hydrogel structures embedding cells to guide tissue formation\ud \ud Originality/value\ud – The originality of this paper is the design and realisation of a 3D microfabrication system able to microfabricate hydrogel matrix embedding cells without inducing cell damage. The ease of use of this system and its potential modularity render this system a novel potential device for application in tissue engineering and regenerative medicine area

Fabrication of 3D Biomimetic Microfluidic Networks in Hydrogels

“…Conversely, microfabrication techniques allow for direct control over microfluidic architecture, but in general lack the resolution to recapitulate the highly tortuous and dense vascular networks formed in vivo. Lithographic molding, computer‐aided laser micromachining, and direct‐write assembly have been used to create geometrically simple microfluidic systems consisting of planar, three‐sided channels on the surface of a matrix. Planar microfluidic networks completely embedded in polymer have been fabricated using advanced lithographic molding, injection molding, strategic placement and removal of needles, and printing of sacrificial materials in self‐healing hydrogels .…”

Fundamentals of Laser‐Based Hydrogel Degradation and Applications in Cell and Tissue Engineering

“…However, photothermal melting of agarose could potentially cause cellular disruption and heat shock protein generation and hence care needs to be taken during stage movement and the laser properties must be tightly controlled to mitigate these risks. This phenomenon was observed where S5Y5 neuroblastoma cells were encapsulated in 3D agarose–alginate hydrogels and subjected to laser‐based microchannel fabrication . Cells residing in the direct ablation path died, while cells in the adjoining regions did not suffer significant damage and were able to fully recover metabolic activity.…”

Preparation of a photocurable hydrogel with adjustable mechanical properties for 3D printing

“…Hydrogels are cross-linked hydrophilic polymers, which can swell but will not be dissolved in water, thus containing large amounts of water inside. Due to different performance, numerous kinds of hydrogels are prepared for various applications, such as tissue adhesives (Hong et al, 2019;Yuk et al, 2019), tissue engineering (De Maria et al, 2014;Yue et al, 2015;Zhang et al, 2017;Lian et al, 2019;Wu et al, 2020), water treatment (Dong et al, 2018;Yu et al, 2018) and drug delivery (Hamedi et al, 2018;Culver et al, 2017;Li and Mooney, 2016).…”