Ultrastructural changes in human gingival fibroblasts after exposure to 2-hydroxy-ethyl methacrylate

Polymerized resin-based materials are successfully utilized in medical applications. One drawback is the release of monomers from the matrix due to an incomplete polymerization or degradation processes. Released monomers can diffuse in the systemic circulation and induce adverse effects to biological tissues. Although there are many hypotheses about the induction of cell death by resin monomers, the underlying mechanisms are still under discussion. The aim of the study was to investigate the morphological modifications in human gingival fibroblasts exposed to 2-hydroxy-ethyl methacrylate (HEMA) to better elucidate the mechanism of cell death induced by resin monomers. Primary cultures of gingival fibroblasts were exposed to 3mM HEMA for 24 h, 72 h, 96 h. Morphological investigations were performed by scanning and transmission electron microscopy, while western blot for caspase-3 was carried out to verify apoptosis. Electron microscopy images showed deep changes in the cell surface and cytoplasm after 72 h and 96 h of HEMA treatment. Autophagic vesicles were easily observed just after 24 h. Cleaved caspase-3 was detected after 72 h of treatment. These findings suggest that resin based materials induced cell death by the cooperation of apoptosis and autophagy mechanisms. The understanding of these mechanisms will lead to the development of smart biomaterials without or with low adverse effects.