Enamel matrix derivative enhances tissue formation around scaffolds used for tissue engineering of ligaments

The following in vitro translational study investigated whether enamel matrix derivative (EMD), an approved biomimetic treatment for periodontal disease (Emdogain) and hard-to-heal wounds (Xelma), enhanced synovial cell colonization and protein synthesis around a scaffold used clinically for in situ tissue engineering of the torn anterior cruciate ligament (ACL). Synovial cells were enzymatically extracted from bovine synovium and dynamically seeded onto polyethylene terephthalate (PET) scaffolds. The cells were cultured in low-serum medium (0.5% FBS) for 4 weeks with either a single administration of EMD at the start of the 4 week period or multiple administrations of EMD at regular intervals throughout the 4 weeks. Samples were harvested and evaluated using the Hoechst DNA assay, BCA protein assay, cresolphthalein complexone calcium assay, SDS-PAGE, ELISA and electron microscopy. A significant increase in cell number (DNA) (p < 0.01), protein content (p < 0.01) and TGFbeta1 synthesis (p < 0.01) was observed with multiple administrations of EMD. Additionally, SDS-PAGE showed an increase in high molecular weight proteins, characteristic of the fibril-forming collagens. Electron microscopy supported these findings, showing that scaffolds treated with multiple administrations of EMD were heavily coated with cells and extracellular matrix (ECM) that enveloped the fibres. Multiple administrations of EMD to synovial cell-seeded scaffolds enhanced the formation of tissue in vitro. Additionally, it was shown that EMD enhanced TGFbeta1 synthesis of synovial cells, suggesting a potential mode of action for EMD's capacity to stimulate tissue regeneration.