Differential Effect of Amelogenin Peptides on Osteogenic DifferentiationIn Vitro: Identification of Possible New Drugs for Bone Repair and Regeneration

Abstract

Enamel matrix proteins (EMP) have been shown to promote regeneration of periodontal ligament and root cementum, and sometimes to enhance the differentiation of bone-forming cells in vitro and new bone growth in vivo. However, the inconsistent and unpredictable effects of EMP that have been reported for bone regeneration may be due to the highly variable composition of this heterogeneous material, which is comprised mainly of amelogenin and amelogenin-derived peptides. The present study has therefore examined the effects of naturally occurring low-molecular-weight (LMW) and high-molecular-weight (HMW) fractions of Emdogain(®) (EMD; Institut Straumann, Basel, Switzerland), a commercially available form of EMP, on osteogenic differentiation of bone precursor cells in vitro. In addition, the effects of chemically synthesized specific components of LMW and HMW-namely, the tyrosine-rich amelogenin peptide (TRAP), a specific amelogenin isoform derived by proteolytic clipping, and a leucine-rich amelogenin peptide (LRAP), an isoform derived by alternative splicing-on bone-forming cell activity were also investigated. Our findings demonstrate that while TRAP suppressed the formation of bone-like mineralized nodules, LRAP upregulated osteogenic differentiation. Furthermore, synthetically produced TRAP and its unique C-terminal 12 amino acid sequence (TCT) also suppressed bone-forming cells, whereas LRAP and its unique C-terminal 23 amino acid sequence (LCT) markedly enhanced terminal differentiation of bone-forming cells. These findings suggest that the differential effects of amelogenin-derived peptide sequences present in EMP could be of potential clinical value, with the novel bioactive TCT peptide as a useful tool for limiting pathological bone cell growth and the unique LCT sequence having therapeutic benefits in the treatment of periodontal and orthopedic diseases.

Effects of enamel matrix proteins on adherence, proliferation and migration of epithelial cells: A real-time in vitro study

“…Previous studies on the effects of EMD, conducted on a variety of research models, have been inconclusive (21,22). A number of ambiguities have made it hard to compare the results between studies and have impeded the characterization of the functions of the different components of EMD.…”

“…A number of ambiguities have made it hard to compare the results between studies and have impeded the characterization of the functions of the different components of EMD. Firstly, previous in vitro studies have used various cell types (epithelial, tongue carcinoma, gingival fibroblast, periodontal ligament, bone marrow-mesenchymal stem cells) obtained from different species (such as, rat, pig and human) (18,19,21–24). Secondly, the studies used a number of different EMPs, such as commercial lyophilized EMD and different fractions isolated from it (<6 kDa, mainly TRAP; >6 kDa, LRAP, sheathing peptides and the full-length AMEL) (21), or numerous recombinants, such as full-length AMEL (22) and chemically synthesized 5.3 kDa TRAP (23).…”

Tracking Endogenous Amelogenin and Ameloblastin In Vivo

“…Spahr, 2006 [36]; Haze, 2009 [8]; Iizuka, 2011 [18]; Tamburstuen, 2011 [10]; Atsawasuwan, 2013 [40], 4. Matsuzawa, 2009 [59]; Iizuka, 2011 [18]; Tamburstuen, 2010 [42]; Amin, 2013 [64]; Atsawasuwan, 2013 [24], 5. Haze, 2009 [8]; Tamburstuen, 2011 [10], 6.…”

Human gingival fibroblast response to enamel matrix derivative, porcine recombinant 21.3-kDa amelogenin and 5.3-kDa tyrosine-rich amelogenin peptide

“…It is suggested that the synthetic fragment of the amelogenin peptide (TRAP) (45 amino acids N-terminal) did not promote wound healing. Stout et al [41] did not find biologic activity for TRAP, and Amin et al [42] found its suppressive effect on periodontal ligament and alveolar bone. TRAP seems not to participate in stimulation of both gingival epithelial cells and fibroblasts.…”