Investigating the Role of Enamel Proteins in Dentogingival Attachment

Objectives: The molecular composition of the internal basal lamina (IBL) that attaches the gingiva to the tooth surface is poorly defined. Laminin332 (Lam332) is the only basement membrane protein that is highly expressed in the IBL. The objective of this study was to develop a model system to investigate the role of maturation stage enamel proteins in enhancing the attachment of epithelial cells to solid surfaces via Lam332.
Methods: Human enamel proteins Amelotin (AMTN), Odontogenic ameloblast-associated (ODAM), and Secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1) were used, alone or in combination with Lam332. Human squamous carcinoma (HSC-2) cells were used as a model of nonkeratinized epithelial cells. Solid surfaces were coated with enamel proteins and/or Lam332. Initial attachment of the cells to the protein coated surfaces was studied using cell culture techniques. A microfluidic device was used to apply shear forces on the cells attached to the protein coated surfaces. The adhesion strength of cells was calculated by measuring the maximum shear stress needed to detach 50% of the cells from the substrates.
Results: Our results showed that a higher number of cells remained firmly attached to a complex of ODAM/Lam332 or SCPPPQ1/Lam332 on solid surfaces compared to Lam332 alone. The adhesion strength of cells attached to the complex of SCPPPQ1/Lam332 was 155±10 dyn/cm² when the shear load was applied for 5 min.
Conclusions: The proposed model system is suitable to identify the molecular mediators of the dentogingival attachment. The enamel protein SCPPPQ1 was able to significantly increase the adhesion strength of epithelial cells to Lam332-coated surfaces (P<0.05; ANOVA). This may enable the development of therapies to combat gingival recession and attachment loss.