Use of Plant Extracts in Polymeric Scaffolds in the Regeneration of Mandibular Injuries

Abstract

Severe loss of bone mass may require grafting, and, among the alternatives available, there are natural biomaterials that can act as scaffolds for the cell growth necessary for tissue regeneration. Collagen and elastin polymers are a good alternative due to their biomimetic properties of bone tissue, and their characteristics can be improved with the addition of polysaccharides such as chitosan and bioactive compounds such as jatoba resin and pomegranate extract due to their antigenic actions. The aim of this experimental protocol was to evaluate bone neoformation in experimentally made defects in the mandible of rats using polymeric scaffolds with plant extracts added. Thirty rats were divided into group 1, with a mandibular defect filled with a clot from the lesion and no graft implant (G1-C, n = 10); group 2, filled with collagen/chitosan/jatoba resin scaffolds (G2-CCJ, n = 10); and group 3, with collagen/nanohydroxyapatite/elastin/pomegranate extract scaffolds (G3-CHER, n = 10). Six weeks after surgery, the animals were euthanized and samples from the surgical areas were submitted to macroscopic, radiological, histological, and morphometric analysis of the mandibular lesion repair process. The results showed no inflammatory infiltrates in the surgical area, indicating good acceptance of the scaffolds in the microenvironment of the host area. In the control group (G1), there was a predominance of reactive connective tissue, while in the grafted groups (G2 and G3), there was bone formation from the margins of the lesion, but it was still insufficient for total bone repair of the defect within the experimental period standardized in this study. The histomorphometric analysis showed that the mean percentage of bone volume formed in the surgical area of groups G1, G2, and G3 was 17.17 ± 2.68, 27.45 ± 1.65, and 34.07 ± 0.64 (mean ± standard deviation), respectively. It can be concluded that these scaffolds with plant extracts added can be a viable alternative for bone repair, as they are easily manipulated, have a low production cost, and stimulate the formation of new bone by osteoconduction.

Keywords: bone regeneration; bone repair; collagen; elastin; hydroxyapatite; jatoba; plant extracts; polymers; pomegranate; scaffolds.

Figure 1

Experimental design. Inclusion criteria: Male Wistar rats (Rattus norvegicus) weighing approximately 360 g and 120 days old. Bone defect of 4.5 mm in the right ramus of the mandible. According to the filling of the bone defect, the animals were divided into three groups: group 1 (Control-C), n = 10, defect without graft, only clot; group 2 (CCJ), n = 10, defect filled with scaffold collagen/chitosan/jatoba resin; group 3 (CHER), n = 10, defect filled with scaffold collagen/nanohydroxyapatite/elastin/pomegranate extract. After 6 weeks of the experimental period, the animals were euthanized and samples from the surgical areas were submitted to macroscopic, radiological, histological, and morphometric analysis.

Figure 2

Digital photograph of scaffolds: (A) CCJ and (B) CHER.

Figure 3

FT-IR spectra of (A) CCJ scaffold: (a) collagen; (b) chitosan; (c) jatoba resin; (d) collagen/chitosan/Jatoba resin. (B) CHER scaffold: (a) collagen; (b) nano-hydroxyapatite; (c) cartilage; (d) pomegranate peel extract; (e) collagen/nanoHA/cartilage/pomegranate peel extract.

Figure 4

SEM micrographs of the scaffolds: (A) superficial CCJ, (B) transversal section CCJ, and (C) superficial CHER, all with 500x magnification, and (D) superficial CHER 6000× magnification.

Figure 5

Pore size distribution histogram for scaffolds (A) CCJ and (B) CHER.

Figure 6

Absorption degree of scaffolds (-●-) CCJ and (-○-) CHER.

Figure 7

Macroscopic characteristics of the bone lesion in the ramus of the mandibles of rats in groups G1 (A–C), G2 (D–F), and G3 (G–I). There were no changes suggestive of infection in the surgical area. It was possible to see the membrane (yellow arrows) in some samples (F).

Figure 8

Radiological images of the skull and ramus of the mandibles of rats in groups G1 (A,B), G2 (C,D), and G3 (E,F). Note the integrity of the bone defect maintained 6 weeks after surgery and the good radiopacity of the mandible.

Figure 9

Histological images of the bone lesions in the branches of the mandibles of rats in groups G1 to G3 stained with Masson’s trichrome. Note the bone neoformation (yellow arrows) from the edges of the bone lesion and remnants of the scaffolds (star) implanted in G2 and G3. Reactive connective tissue (red arrows).

Figure 10

Photomicrographs of the bone lesions in the branches of the mandibles of rats in groups G1 to G3 stained with Picrosirius red in the absence and presence of polarized light. Note the birefringence of the tissues present in the bone lesion.