Study on 3D-Printed Emodin/Nano-Hydroxyapatite Scaffolds Promoting Bone Regeneration by Supporting Osteoblast Proliferation and Macrophage M2 Polarization

Abstract

The treatment of bone defects caused by diseases, trauma, or tumor has always been a great clinical challenge. Implantation of bone biomaterials into bone defect areas is an effective method for bone injury repair. In this study, we used three-dimensional (3D) printing technology to prepare nano-hydroxyapatite (nHA)/sodium alginate (SA)/gelatin (Gel) hydrogel scaffolds loaded with different ratios (0, 0.13, 0.26, 0.39, 0.53, and 0.79‰) of emodin (EM) (EM/nHA/SA/Gel). Scanning electron microscopy showed that the scaffolds had a smooth surface without fracture and nHA was evenly distributed on the surface. The cell proliferation and migration results showed that the 0.39‰ EM group, in particular, could significantly promote the proliferation and migration of mouse embryonic osteoblast precursor (MC3T3-E1) cells and significantly increase the mRNA expression of osteogenic differentiation-related genes (bone morphogenetic protein/BMP-2, BMP-9, osteocalcin). In addition, the 0.39‰ EM group exhibited the best effect on osteogenic differentiation-related proteins (alkaline phosphatase, Runx 2, OSX). The expression of M2 polarization-related genes (arginase-1, CD206) also significantly increased after the treatment with the 0.39‰ EM group. Micro-CT showed that in the rat skull defect model, the EM/nHA/SA/Gel scaffold group significantly promoted bone regeneration after being implanted into the skull for 30 days. Our results indicate that the EM/nHA/SA/Gel hydrogel scaffolds can not only directly promote the proliferation and differentiation of osteoblasts but also indirectly promote osteogenic differentiation by supporting M2 polarization of macrophages. EM/nHA/SA/Gel hydrogel scaffolds are potential bone tissue engineering materials for bone regeneration.

Calcium Phosphate Biomaterials for 3D Bioprinting in Bone Tissue Engineering

“…Bone marrow mesenchymal stem cells (BMSCs) [87] Nanohydroxyapatite Sodium alginate (SA)/gelatin (Gel) Emodin-drug and mouse embryonic osteoblast precursor (MC3T3-E1) cells [88] Nanohydroxyapatite Gelatin (Gel), quaternized chitosan (QCS) Mesenchymal-stem-cell-derived exosomes [89] Hydroxyapatite Collagen MG63 cells and human adipose stem cells [90] α-TCP Alginate Mouse calvaria-derived preosteoblast cells (MC3T3) [91] Whitlockite and hydroxyapatite…”

“…Also, in vitro cell assessment revealed excellent cytocompatibility and increased ALP expression (Figure 4a) in the HAp/collagen scaffold. In a study, 3D-printed scaffolds with nanohydroxyapatite (nHAp)/sodium alginate/gelatin hydrogel were loaded with emodin [88]. Emodin has demonstrated a direct and effective promotion of osteoblast proliferation, migration, differentiation and mineralization.…”

“…To achieve homogeneous and delicate mixing of bioinks containing nano/microparticles and cells, A. Bhattacharyya and colleagues developed a semi-automated twin screw extruder head and printed alginate/α-TCP/osteoblast cell scaffolds with a manufactured system [91]. [88]; (e) The heights of the 3Dprinted samples that were produced from GelMA and GelMA containing calcium phosphate micro/nanoparticles [96]. (Refs.…”

“…While octacalcium phosphate holds promise for bone tissue engineering due to its ability to convert to hydroxyapatite through hydrolysis in physiological environments, the challenge in the control of its hydrolysis prompts the exploration of strategies involving its integration with hydrogels. [88]; (e) The heights of the 3D-printed samples that were produced from GelMA and GelMA containing calcium phosphate micro/nanoparticles [96]. (Refs.…”

“…(a)The ALP activity after BMSCs were cultured on HAp/collagen scaffolds for 7 and 14 days[87]; (b) The compressive modulus of α-TCP/GelMA hydrogel samples containing 0, 0.125, 0.25 or 0.5 wt%, α-TCP before the calcium phosphate phase transition (0 h) (n.s. = not significant) and (c) after the calcium phosphate phase transition (36 h) (* p < 0.05)[95]; (d) Micro-CT images of implanted composite hydrogel scaffolds in a rat defect model after 30 days[88]; (e) The heights of the 3D-printed samples that were produced from GelMA and GelMA containing calcium phosphate micro/nanoparticles[96]. (Refs [87,88,95,96].…”