Currently, osteoporosis has become a worldwide major health concern. To increase the bone mineralisation and prevent osteoporotic fracture, nacre is a promising solution. Nacre, or mother of pearl, is capable to increase the cell osteogenic activity. We have confirmed the osteogenic potential of a particular nacre extract, ESM (Ethanol Soluble Matrix) on osteoarthritis (OA) osteoblasts, which are known to have difficulties to mineralise. But those nacreous osteogenic compounds have not been identified yet. Herein, we developed some new methods to identify the active compounds. We evaluated their mineralisation induction capacity on OA osteoblasts. Therefore, ESM was extracted with ethanol from nacre powder of pearl oyster Pinctada margaritifera. We selected molecules with ion-exchange resin to achieve cationic ESM (ESMc) and anionic ESM (ESMa). Both were then tested for 28 days at 200 μg/ml on subchondral osteoblasts from OA patients undergoing total knee replacement. Alizarin Red staining was performed to test their capacity of mineralisation and quantified at 405 nm. Size-exclusion and strong ion-exchange HPLC were used to separate ESMc and ESMa and compounds were then identified by mass spectrometry. Alizarin Red assay demonstrated an increase of calcium deposition in OA osteoblasts in presence of ESMc. But in presence of ESMa no mineralisation is observed. HPLC and mass spectrometry showed that ESMc and ESMa were composed differently. In conclusion, we acquired 2 totally different fractions from ESM, ESMc and ESMa. ESMa did not exert any mineralisation induction capacity on OA osteoblasts. The osteogenic compounds of ESM are cationic. This strategy associating ion-exchange resin, OA osteoblasts, HPLC and mass spectrometry could be effective for the identification of nacreous osteogenic molecules. This improvement will advance the treatment of osteoporosis with nacre extract.
Disclosure: The authors declared no competing interests.