The lysine degradation pathway analyzed with 1H-NMR-targeted metabolomics of MG63 cells on poly(l-lactide)-based scaffolds

Abstract

A biomaterial is one of the key elements in tissue engineering, particularly for bone regeneration, as it withstands the human physiological environment and support essential cellular functions. Poly(L-lactide) (PLLA) is widely employed for biomedical applications, although there have been some drawbacks. We successfully developed PLLA composites using plasma-assisted and electrospinning methods. Conventional studies focus deeply on molecular interactions between cells and materials; however, studies aimed at understanding how cells metabolically respond to these materials have been limited. This work used ¹H-NMR-based metabolomics and multivariate statistical analysis to evaluate how PLLA composites metabolically guided MG63 osteoblast-like cells cultured on them. It was found that cells reacted uniquely on each scaffold type. PLS-DA suggested that succinic acid (2.39 ppm) and 3-hydroxy-L-proline (1.47 ppm) were the two metabolites with the highest variable importance in projection (VIP) values. Pathway enrichment analysis revealed that lysine degradation was considerably enriched (enrichment ratio: 2.0; p < 0.05). We further validated this prediction by supplementation with L-lysine at various concentrations, and it was confirmed that L-lysine supplementation significantly increased alkaline phosphatase activity, collagen synthesis, and mineralization, especially at 400 μM after 7 d. Consistent with this, the levels of lysine degradation intermediates were much lower on cellulose-containing scaffolds. These data suggest that activation of the lysine degradation pathway supports osteogenic activity.