FeS2-incorporated 3D PCL scaffold improves new bone formation and neovascularization in a rat calvarial defect model

Abstract

199Three-dimensional (3D) scaffolds composed of various biomaterials, including metals, ceramics, and synthetic polymers, have been widely used to regenerate bone defects. However, these materials possess clear downsides, which prevent bone regeneration. Therefore, composite scaffolds have been developed to compensate these disadvantages and achieve synergetic effects. In this study, a naturally occurring biomineral, FeS₂, was incorporated in PCL scaffolds to enhance the mechanical properties, which would in turn influence the biological characteristics. The composite scaffolds consisting of different weight fractions of FeS₂ were 3D printed and compared to pure PCL scaffold. The surface roughness (5.77-fold) and the compressive strength (3.38-fold) of the PCL scaffold was remarkably enhanced in a dose-dependent manner. The in vivo results showed that the group with PCL/ FeS₂ scaffold implanted had increased neovascularization and bone formation (2.9-fold). These results demonstrated that the FeS₂ incorporated PCL scaffold might be an effective bioimplant for bone tissue regeneration.

Keywords: 3D printed; Bone formation; FeS2; Mechanical properties; PCL.

Figure 1

(A) Schematical illustration of this study showing the scaffold fabrication and animal model. (B) FT-IR results and (C) TGA curves for PCL, PF5, PF10, and PF20 scaffolds.

Figure 2

(A) Optical and (b) SEM images of the prepared scaffolds with the corresponding (C) EDS spectra. (D) Surface morphology of the scaffolds taken by AFM.

Figure 3

Mechanical properties of the scaffolds, including (A) stress–strain curve and (B) compressive modulus. (C) Schematic showing the interaction during compressive stress.

Figure 4

(A) Fluorescence images of 4′,6-diamidino-2-phenylindole (DAPI)-stained scaffolds for cell recruitment study. (B) Quantitative results showing the number of cells on the scaffolds.

Figure 5

(A) Representative micro-CT images of newly formed bone after 6 and 12 weeks. (B) Morphometric analysis showing the newly formed bone volume fraction.

Figure 6

Histological analysis showing representative (A) H&E, (B) MT, and (C) IHC staining images of PCL, PF5, PF10, and PF20 groups at 6 and 12 weeks post-surgery. In the image, the rectangle indicates inflammatory cells; the star indicates osteoid; the black arrow indicates multinucleated giant cells; the blue arrow indicates blood vessel; the green arrow indicates osteocyte; the dotted green line indicates osteoblasts. Abbreviations: NB, new bone; SF, scaffold; FT, fibrous tissue.

Figure 7

(A) Micro-CT images showing Microfil-labeled blood vessels after 12 weeks. (B) Western blot analysis of COL1, OCN, and OPN expression after 2 weeks. Illustration of the bone formation process in this study showing (C) recruitment of progenitor MSCs and vessel formation as well as (D) VEGF/BMP-2 cycle.