Lack of a cornea’s donor is still a huge problem in ophthalmology leaving over 98% of people waiting for the transplantation. As the solution, bioengineered scaffolds, mimicking the fibrous structure of the corneal stroma are proposed. To obtain a full regeneration, such substrates should provide both cornea cells repopulation and optical transparency. In the native cornea, the hierarchical microstructure of collagen fibrils is responsible for maintaining those properties. Studies have proved that both primary morphology (organization of the fibres) and secondary morphology (fibres nanotopography) have a huge impact on the phenotype of the cells.
In our study, we investigated the impact of different primary (aligned and random fibres) and secondary microstructure (shish-kebab, beads-on-strings) of the electrospun PCL nonwovens on the viability of different cells (macrophages, keratinocytes, fibroblasts) to check whether they show a preference for a specific type of surface. We also examined the correlation between the morphology of the substrate and the optical transparency of the scaffold.
The nonwoven was obtained by the electrospinning method based on polycaprolactone (PCL). To obtain the aligned fibres the rotating drum collector was used. Coaxial electrospinning was used to prepare beads-on-strings fibres using different concentrations of PCL solution in a shell/core part. To obtain shish kebab morphology, the neat fibres were modified by directional crystallization in PCL solution. The morphology of the samples was observed under scanning electron microscopy. The influence of the obtained fibres morphology on the physicochemical properties of the membrane (wettability, surface energy) was also investigated. The light transmission through the scaffold was examined by UV-VIS analysis. A biocompatibility test was performed by contacting the cells with the fibrous scaffold after 3 and 7 days.
The SEM observations showed the presence of the randomly oriented and aligned nano- and submicron fibres. All of the obtained fibres have unimodal size distribution in a range 400 – 1000nm. The directional crystallization enabled achieving fibres with lamellae parts, characteristic of the shish-kebab morphology. The use of coaxial electrospinning enabled to obtain bead-on-strings fibres with a reduced core diameter (in a range of 200 – 700nm). Independently on the modification all of the samples exhibited hydrophobic properties (contact angle ~130°). The research also showed a slight difference in translucency between random oriented and aligned fibres, however, the best light transmission was recorded for beads-on-strings fibres. All of the samples exhibited high viability of all cells types independently of the orientation nor morphology of the fibres. None of the tested scaffolds showed a cytotoxic effect.
Electrospun nanofibers with different microstructures were successfully obtained and demonstrate biological and optical properties that indicate the strong potential as extracellular matrix – mimicking substrates for cornea regeneration.
This work was supported by the subsidy of the Ministry of Education and Science for the AGH University of Science and Technology in Kraków No 126.96.36.1997.
1. Gain, P. et al. JAMA Ophthalmol. 134, 167–173 (2016) 2. Kennedy, K. M. et al. Acta Biomater. 50, 41–55 (2017) 3. Zaarour, B. et al. ChemistrySelect 5, 1335–1348 (2020)