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Corneal blindness is one of the leading causes of blindness worldwide. A cornea transplant surgery provides ultimate cure, however, it is restricted by donor tissue shortage. Thus, we aim to develop 3D bioprinted full thickness corneas to address this lack of donor material. To ensure robust transport, handling, and suturing, the bioprinted cornea's mechanical properties needs to be improved. This could be achieved by incorporating a microfiber support structure into the bioink material to reinforce its stability.
Melt electrowriting (MEW) technique allows to produce microfiber scaffolds with high resolution and defined fiber thickness, by electrostatically drawing out a polymer melt of a heated syringe on a moving collector [1]. In this study, medical grade poly(e-caprolactone) (PCL) was selected as a printing material due to its well-established use in MEW and medical applications [2]. PCL is biocompatible, easy to sterilize, and possesses good mechanical properties.
Scaffolds with different parameters were fabricated via MEW. The fiber thickness and density influenced the transparency of the scaffolds. Moreover, the printing parameters, i.e. applied pressure, collector speed, and voltage, had to be balanced to achieve optimal fiber stacking [3]. Loss of fiber alignment resulted in decreased optical clearance, which is of particular relevance in this work.
The PCL microscaffolds significantly increased mechanical stability of the corneal hydrogel. Additionally, the complete structure was successfully sutured in human donor corneas ex vivo. PCL is a biodegradable polymer with various factors that affect its degradation kinetics [4]. Therefore, it will be essential to evaluate degradation of the corneal microscaffolds under the inflamed environment after the cornea surgery.
Overall, this research aims to design and fabricate PCL microscaffolds utilizing MEW, which will reinforce hydrogel-based full thickness corneas. Ultimately, this will allow clinical handling and suturing of bioprinted corneas, which are a promising alternative to donor corneal tissue.
Acknowledgement: This work is supported by the European Health and Digital Executive Agency (project number 101191726).
Disclaimer: Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency. Neither the European Union nor the European Health and Digital Executive Agency can be held responsible for them.
[1] P.D. Dalton, 2017. Melt electrowriting with additive manufacturing principles. Current Opinion in Biomedical Engineering 2, 49-57.
[2] C. Böhm, P. Stahlhut, J. Weichhold, A. Hrynevich, J. Teßmar, P.D. Dalton, 2021. The Multiweek Thermal Stability of Medical-Grade Poly(ε-caprolactone) During Melt Electrowriting. Small 18, 2104193.
[3] G. Hochleitner, A. Youssef, A. Hrynevich, J.N. Haigh, T. Jungst, J. Groll, and P.D. Dalton, 2016. Fibre pulsing during melt electrospinning writing. BioNanoMaterials 17, 159-171.
[4] M. Bartnikowski, T.R. Dargaville, S. Ivanovski, D.W. Hutmacher, 2019. Degradation mechanisms of polycaprolactone in the context of chemistry, geometry and environment. Progress in Polymer Science 96, 1-20
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