Understanding the interaction between cells and materials is fundamental to tissue engineering. The scientific community's focus on biomaterial-cell interactions has largely fallen on cellular phenotypes, proteins, and nucleic acids, while molecular mechanisms within cells are often overlooked. However, it is expected that cellular metabolism will be significantly influenced by biomaterials. In this regard, direct measurement of metabolites can elucidate perturbation in cellular metabolism, helping to explain and predict changes in cellular phenotypes. In this work, we performed in vitro based metabolomics study to identify changes in cellular metabolism upon interaction with calcium phosphate based biomaterials.
Calcium phosphates, including hydroxyapatite (HAP), β-tricalcium phosphate (β-TCP), and bicalcium phosphate (BCP), were applied as the model materials to investigate the cellular response. Sintered materials were characterized by XRD to determine the crystalline structure. NIH/3T3 cells were directly seeded on the materials and harvested on days 1, 3, 5, and 7, following methanol-chloroform mixture extraction protocol to collect metabolites and lipids. Targeted quantitative metabolite analysis was carried out utilizing several HPLC methods in combination with mass spectrometric detection. Obtained metabolomics data were further analysed using MetaboAnalyst 5.0.
The results showed that different calcium phosphate components induced different changes in cellular metabolism. Pathway analysis comparing metabolites profiles between cells grown on HAP, β-TCP, and BCP from different time points and control cell culture showed that metabolism and biosynthesis of several amino acids, acylcarnitines, and lipids were changed. For example, we observed changes in glutathione and arginine metabolism which plays important roles in antioxidant defence and immune response. The observed changes in amino acid metabolism were inter-interpretable with previously reported gene expression and protein activity data for selected materials.
In our study, we confirmed the calcium phosphate based biomaterials influence on cell metabolism. Distinct changes in metabolite profiles for cells seeded on calcium phosphate ceramics compared to controls were observed. Most of the detected metabolites exhibited time-dependent changes indicating a cellular adaption mechanism to biomaterial-induced perturbation. These results provide evidence about the biomaterials chemical composition influence on cellular metabolism and its link to gene expression level. This proves that metabolomics is a useful tool for studying metabolomics-material interactions to improve the current understanding of the mechanism governing cell behaviours."