The potential of mulberry and non-mulberry silk fibroin blends as bioinks for meniscus regeneration by 3D-bioprinting

Not scheduled
5m
ICE Krakow

ICE Krakow

ul. Marii Konopnickiej 17 30-302 Kraków

Speaker

Jeyakumar, Vivek (University for Continuing Education Krems)

Description

INTRODUCTION
The meniscus is vital for biomechanical and anatomical purposes in the knee, which is frequently injured. Among the diverse biomaterials used for 3D-bioprinting in meniscus regeneration research, silk fibroin (SF) derived from mulberry Bombyx mori (BM) silkworm is extensively studied. Its main drawbacks are the challenge to print it without another material and its lack of the Arg-Gly-Asp (RGD) sequence for cell adhesion. Therefore, non-mulberry silk types like the one from Antheraea mylitta (AM), with the inherent RGD motif, are also being explored. Thus, our approach of blending mulberry and non-mulberry silk fibroin provides a new approach to obtain a printable hydrogel for meniscus regeneration.
METHODOLOGY
Bioink preparation: The cocoons were cut and degummed. BM SF fibers were dissolved and the solutions were dialysed against water for 2 days with regular water exchanges.
Gelation kinetics: BM and AM SF solutions were mixed in different proportions without any crosslinker and diluted to yield blends with 3-10% (w/v) SF. The absorbance at 540 nm was monitored for 3 h at 37°C in a plate reader.
Printability: BM and AM SF solutions were mixed (1:1) to yield 5% and 10% (w/v) SF. Solutions with/without ruthenium photoinitiator kit were prepared. After gelation in syringes at 37°C the gels were extruded into the shape of a meniscus on a bioprinter with/without visible light for crosslinking.
Cell viability: Chondrocytes were seeded into 10% (w/v) BM SF and SF blend with ruthenium photoinitiator. The gels were incubated at 37°C for 3 days, before staining with a Viability/Cytotoxicity Kit.
SEM: The gels for cell viability evaluation were iamged with FlexSEM 1000.
RESULTS
Gelation kinetics: The addition of more AM SF than BM SF has proven to be advantageous for the gelation time. Only when three times as much AM SF was added, the gelation time increased again.
Printability: Printing 5% (w/v) SF blends and already crosslinked and non-crosslinked 10% (w/v) SF blend resulted in unstable constructs. Therefore, the 10% (w/v) SF blend with crosslinking during printing has proven to be the best condition for printing a meniscus.
Cell viability: In the BM SF hydrogel, only a few live and dead cells were detected. In the SF blend hydrogels, no dead cells and a higher number of living cells were found.
SEM: The combination of BM SF and AM SF led to a higher pore size number than the use of BM SF alone. The pores made up approx. 25% of the total area.
CONCLUSION
Our study has shown that the BM and AM SF blend is suitable as a novel bioink, since it possesses self-gelation properties. With the appropriate proportion of SF, the solution gels within 90 min and can be applied as bioink with photocrosslinking during extrusion on a bioprinter. Our first results regarding printability and property analysis of SF blend hydrogels show promising potential for the application as bioink. Additionally, the initial cell viability studies showed that the blend constitutes a better environment for cell proliferation and survival than BM SF alone.
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