3D bioprinted material for corneal stroma regeneration resistant to bacterial and fungal infection

Abstract

Purpose : To assess whether 3D bioprinted, scaffold-immobilized antimicrobial peptides (AMPs) derivatives, BMAP27(1-18) and hLF(1-11), can inhibit bacterial colonization, to obtain infection-resistant 3D bioprinted hemi-corneas.

Methods : The research followed the tenets of the Declaration of Helsinki and approved by REK Norway (REK n.2013/803). 3D bioprinting was used to produce transparent nanocellulose- and alginate- based 3D constructs containing human collagen type I. Functionalized 3D bioprinted scaffolds with AMPs were characterized by contact angle, transparency and nano-indentation measurements. The antimicrobial and antifungal activity of the peptides in solution were investigated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods against Staphylococcus epidermidis ATCC 35984, S. aureus ATCC 25923, S. epidermidis ATCC 12228, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Candida albicans ATCC 90028. The antimicrobial and antifungal activity of the AMP-modified scaffolds were studied against P. aeruginosa and C. albicans reference strains by colony forming unit (CFU) counts, and their biocompatibility was investigated by measuring the viability of primary human/cadaver-isolated corneal stromal-mesenchymal stromal cells (CS-MSCs).

Results : The original and modified peptides showed MIC and MBC values of 1 – 4 (2 – 8) µM and 16 – >128 (32 – >128) µM, respectively, against S. epidermidis ATCC 35984, S. aureus, S. epidermidis ATCC 12228, P. aeruginosa, E. coli and C. albicans, while cCBD-BMAP27(1-18) and cCBD-hLF(1-11) of 1 – 32 (2 – >64) µM 8 – 128 (16 – >128) µM, respectively, against all the pathogens. The modified scaffolds containing BMAP27(1-18) and hLF(1-11) peptides attached to the scaffolds, demonstrated the ability to kill 80% and 60% of P. aeruginosa, and 60% and 70% of C. albicans. All the 3D bioprinted scaffolds showed cytocompatibility towards CS-MSCs.

Conclusions : We could successfully combine 3D bioprinting with immobilization of AMPs that show promising antimicrobial and antifungal activity against two of the most dangerous pathogens to the cornea, while a good cytocompatibility for the CS-MSCs could be achieved. Optimal bioink composition and cellularization of tissue equivalents are essential in fine-tuning a method to promote the current 3D bioprinting technique as a future treatment modality for corneal regeneration.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.