Abstract
The recovery of impaired periodontium is still a challenge to the treatment of periodontitis. This study was the first to apply the mesoporous hydroxyapatites/chitosan (mHA/CS) composite scaffold to periodontal regeneration. The aim of our study is to evaluate the biological effects of mesoporous hydroxyapatite/chitosan (mHA/CS) loaded with recombinant human amelogenin (rhAm) on periodontal regeneration. The physicochemical properties of mHA/CS scaffolds were examined by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. Then, the biological effects of the mHA/CS loaded with rhAm were evaluated, including antibacterial effect, controlled-release capacity, osteogenic and cementogenic effects in vitro and in vivo. The antibacterial effect was tested on 1.5 mg/mL CS; 3 mg/mL mHA; 2.25 mg/mL mHA/CS; 4.5 mg/mL mHA/CS and 20 μg/mL rhAm. Tryptic Soy Broth culture medium was used as a baseline control. Osteogenic effect of rhAm (20 μg/mL rhAm), mHA/CS (4.5 mg/mL mHA/CS), and mHA/CS-rhAm (4.5 mg/mL mHA/CS and 20 μg/mL rhAm) on human periodontal ligament cells (hPDLCs) was evaluated in osteogenic media. The hPDLCs treated either with osteogenic media or Dulbecco's modified Eagle's medium (DMEM) alone were used as the baseline control. In the animal model, 4-week-old nude mice (BALB/c) (n = 6) implanted with root slices subcutaneously were used to observe the cementogenic effect in vivo. The root slices were treated with rhAm (20 μg/mL rhAm), mHA/CS (4.5 mg/mL mHA/CS), and mHA/CS-rhAm (4.5 mg/mL mHA/CS and 20 μg/mL rhAm). The root slices treated with osteogenic medium alone were used as the baseline control. The analyses showed that the mHA/CS particles were 2 μm in diameter and had a uniform pore size. The mesoporous structure was 7 nm in diameter and its surface area was 33.95 m2/g. The scaffold exhibited antibacterial effects against Fusobacterium nucleatum and Porphyromonas gingivalis. The mHA/CS scaffold sustainably released rhAm. The mHA/CS loaded with 20 μg/mL rhAm upregulated ALP activity, the expression levels of osteogenesis-related genes and proteins in vitro. Additionally, it promoted the formation of cementum-like tissue in vivo. Our findings suggest that mHA/CS loaded with 20 μg/mL rhAm could inhibit the growth of periodontal pathogens and promote the formation of bone and cementum-like tissue.
Highlights
Periodontitis, as one of the most prevalent oral diseases, which is characterized by the destruction of alveolar bone, which will result in the loosening of teeth and even the loss of teeth (Miranda et al, 2016)
The results showed that Alkaline Phosphatase (ALP) staining in the group recombinant human amelogenin (rhAm) and group mesoporous hydroxyapatites (mHA)/CS-rhAm was stronger in color than that in the group mHA/CS, C and D
The dead bacteria were washed away before the staining, which may explain the sparse distributions of staining in 4.5 mg/mL mHA/CS group and 1.5 mg/mL CS group. These results suggested that the mHA/CS scaffold could inhibit the growth of F. nucleatum and P. gingivalis in both planktonic cultures and biofilms and that the antibacterial effects should be attributed to chitosan
Summary
Periodontitis, as one of the most prevalent oral diseases, which is characterized by the destruction of alveolar bone, which will result in the loosening of teeth and even the loss of teeth (Miranda et al, 2016). Periodontal treatment can eliminate chronic inflammation and infection and stop the progression of disease. Many studies have focused on the use of tissue engineering techniques to achieve the periodontal regeneration, which include three major elements: seed cells, scaffolds, and growth factors (Ogawa et al, 2016). Periodontal ligament cells have been convinced as the ideal seed cells for periodontal regeneration (Gauthier et al, 2017), which have the capacity of forming cementum-like and periodontal ligament-like tissues (Mrozik et al, 2017). Scaffolds play a vital role in supporting cell adherence and proliferation, maintaining space, and sustainably releasing of growth factors. The scaffold should be biocompatible and degradable, as it will eventually be replaced by the newly formed tissue (Han et al, 2014; Liu et al, 2016)
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