Introduction: Different polymers such as polycaprolactone are being assessed for their suitability for cartilage reconstruction. So far, all the polymer types studied have had their limitations, such as low hydrophilicity, which impairs cell adhesion. In this study, a vanillin-based renewable polymer was assessed for its cell compatibility regarding cartilage progenitor cells (CPCs). Additionally, it was analyzed if CPCs migrate into the polymer and express cartilage-specific markers such as aggrecan, elastin or collagen II.

Methods: Vanilin was mixed at different ratios with Trimethylolpropane tris(3-mercaptopropionate) (TMPMP), and the mixture was crosslinked via light-induced polymerization in acetonitrile under ambient conditions. CPCs were seeded in plates and expanded to a confluence of approx. 80 %. A slice of each polymer was added to the cells and incubated for another 5 days. Cell viability was analyzed using the calcein AM assay (live cells, green; dead cells, red). CPCs were seeded on the polymer to analyze migration and marker expression and cultured for 21 days. Histological and immunohistochemical methods were used to stain for aggrecan, elastin, collagen II, and collagen I.

Results: The vanillin polymer synthesized via a light-induced crosslinking process in acetonitrile showed the best cell compatibility. At a vanillin to TMPMP ratio of 1:0.75, cells were able to migrate into the polymer and cartilage-specific markers, except for collagen II, were expressed.

Conclusion: CPCs can interact with those vanillin-based polymers, which show high cell compatibility, and begin to express cartilage-specific extracellular matrix. This is a promising result for the potential use of vanillin-based polymers as an implant material to repair cartilage defects.

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