Pedro Caballero
Introduction
The avascular and aneural nature of cartilage limits its capacity to self-repair, rendering degenerative cartilage diseases largely irreversible. Laponite, a synthetic nanoclay, has demonstrated bioactivity and potential in promoting cartilage formation, representing a promising biomaterial for cartilage regeneration. One hypothesis is laponite’s degradation products acting through ion-mediated cellular pathways.
Methods
ATDC5 cells were seeded in 20 μL droplets of 50,000 cells and cultured for 7 days in chondrogenic media at varying laponite concentrations: 0, 10, 50 and 100 μg/mL. Parallel experiments used ionic solutions equivalent to those released by 100 µg/mL laponite. Alcian blue staining assessed GAG concentrations, and gene expression of SOX9 and COL2 was analysed using RT-qPCR. Images were taken using light microscopy, and intensities quantified by CellProfiler.
Results
Alcian blue staining increased dose-dependently with laponite concentration. Quantitative analysis showed intensity increased from 0.5458 ± 0.1220 (n=3) to 0.9108 ± 0.0169 (n=3) at 100 μg/mL, a 1.67-fold increase. One-way ANOVA showed this was significant (p<0.0003).
Degradation ions did not increase staining, with the 100 μg/mL laponite sample significantly higher (p<0.0022).
RT-qPCR showed no significant differences. However, SOX9 expression increased ~4.7-fold and COL2 ~1.7-fold at 100 µg/mL.
Conclusion
Laponite appears to promote chondrogenesis, but its charged nature may increase Alcian blue uptake. Degradation ions had no effect. Gene expression showed non-significant upregulation. Laponite’s chondrogenic effect remains inconclusive
Authors
Pedro Caballero
Southampton University, Southampton, United Kingdom