Biomimetic Enamel Regeneration Mediated by Leucine-Rich Amelogenin Peptide

Abstract

We report here a novel biomimetic approach to the regeneration of human enamel. The approach combines the use of inorganic pyrophosphate (PP) to control the onset and rate of enamel regeneration and the use of leucine-rich amelogenin peptide (LRAP), a nonphosphorylated 56-amino acid alternative splice product of amelogenin, to regulate the shape and orientation of growing enamel crystals. This study builds on our previous findings that show LRAP can effectively guide the formation of ordered arrays of needle-like hydroxyapatite (HA) crystals in vitro and on the known role mineralization inhibitors, like PP, play in the regulation of mineralized tissue formation. Acid-etched enamel surfaces of extracted human molars, cut perpendicular or parallel to the direction of the enamel rods, were exposed to a PP-stabilized supersaturated calcium phosphate (CaP) solution containing 0 to 0.06 mg/mL LRAP for 20 h. In the absence of LRAP, PP inhibition was reversed by the presence of etched enamel surfaces and led to the formation of large, randomly distributed plate-like HA crystals that were weakly attached, regardless of rod orientation. In the presence of 0.04 mg/mL LRAP, however, densely packed mineral layers, comprising bundles of small needle-like HA crystals, formed on etched surfaces that were cut perpendicular to the enamel rods. These crystals were strongly attached, and their arrangement reflected to a significant degree the underlying enamel prism pattern. In contrast, under the same conditions with LRAP, little to no crystal formation was found on enamel surfaces that were cut parallel to the direction of the enamel rods. These results suggest that LRAP preferentially interacts with ab surfaces of mature enamel crystals, inhibiting their directional growth, thus selectively promoting linear growth along the c-axis of enamel crystals. The present findings demonstrate a potential for the development of a new approach to regenerate enamel structure and properties.

State of the Art Enamel Remineralization Systems: The Next Frontier in Caries Management

“…In vitro studies have shown treatment of enamel lesions with leucine-rich amelogenin peptide reduced lesion depth and allowed biomimetic reconstruction of enamel by promoting linear growth of mature enamel crystals along the c-axis [Bagheri et al, 2015;Mukherjee et al, 2016;Shafiei et al, 2015]. The addition of mineralization inhibitors such as inorganic pyrophosphate or matrix metalloproteinase to synthetic amelogenin assemblies was able to better regulate size, shape, and orientation of a strongly adherent new mineral layer, while preventing undesirable protein occlusion within newly formed crystals [Kwak et al, 2017;Prajapati et al, 2018].…”

Hydroxyapatite Formation Coexists with Amyloid-like Self-Assembly of Human Amelogenin

“…Although not fully understood, the biomimetic approach has utilized amelogenin to regenerate enamel-like materials on teeth in gentle and close to physiological conditions [6]. Full-length amelogenin [7], leucine-rich amelogenin peptide (LRAP) [8] and other amelogenin-derived peptides [9] have all been tested and proved to have great potential in dentistry or biomaterials.…”

Current Overview of Remineralization Materials and Technologies

“…82,83 Amelogenin düşük maliyetli ve daha güvenli bir alternatifi olan 56 amino asitten oluşan lösin bakımından zengin amelogenin peptidinin lezyon derinliğini düşürdüğünü ve c-ekseni boyunca olgun mine kristallerinin doğrusal büyümesini teşvik ederek mine biyomimetik rekonstrüksiyonunu sağladığı gösterilmiştir. 84,85 İnorganik pirofosfat veya matris metaloproteinaz gibi mineralizasyon in-hibitörleri eklenen sentetik amelogeninlerin yeni mineral katmanının boyutunu, şeklini ve oryantasyonunu daha iyi düzenleyebildiği bulgulanmıştır. 85 Amelogenin elde edilmesi ve depolanması zordur ve amelogenin ile teşvik edilen mine tabakasının büyümesi uzun süre alır, bu nedenle klinik kullanım için uygun değildir.…”

“…84,85 İnorganik pirofosfat veya matris metaloproteinaz gibi mineralizasyon in-hibitörleri eklenen sentetik amelogeninlerin yeni mineral katmanının boyutunu, şeklini ve oryantasyonunu daha iyi düzenleyebildiği bulgulanmıştır. 85 Amelogenin elde edilmesi ve depolanması zordur ve amelogenin ile teşvik edilen mine tabakasının büyümesi uzun süre alır, bu nedenle klinik kullanım için uygun değildir. Ayrıca, amelogeninin vitro olarak apatit çekirdeklenmesini arttırdığı bulgulanmış olsa da, benzer biyomineralizasyonun in vivo olarak gerçekleştiğine dair doğrudan bir kanıt yoktur.…”