Effect of Strontium Substitution on the Physicochemical Properties and Bone Regeneration Potential of 3D Printed Calcium Silicate Scaffolds

Abstract

In this study, we synthesized strontium-contained calcium silicate (SrCS) powder and fabricated SrCS scaffolds with controlled precise structures using 3D printing techniques. SrCS scaffolds were shown to possess increased mechanical properties as compared to calcium silicate (CS) scaffolds. Our results showed that SrCS scaffolds had uniform interconnected macropores (~500 µm) with a compressive strength 2-times higher than that of CS scaffolds. The biological behaviors of SrCS scaffolds were assessed using the following characteristics: apatite-precipitating ability, cytocompatibility, proliferation, and osteogenic differentiation of human mesenchymal stem cells (MSCs). With CS scaffolds as controls, our results indicated that SrCS scaffolds demonstrated good apatite-forming bioactivity with sustained release of Si and Sr ions. The in vitro tests demonstrated that SrCS scaffolds possessed excellent biocompatibility which in turn stimulated adhesion, proliferation, and differentiation of MSCs. In addition, the SrCS scaffolds were able to enhance MSCs synthesis of osteoprotegerin (OPG) and suppress macrophage colony-stimulating factor (M-CSF) thus disrupting normal bone homeostasis which led to enhanced bone formation over bone resorption. Implanted SrCS scaffolds were able to promote new blood vessel growth and new bone regeneration within 4 weeks after implantation in critical-sized rabbit femur defects. Therefore, it was shown that 3D printed SrCS scaffolds with specific controllable structures can be fabricated and SrCS scaffolds had enhanced mechanical property and osteogenesis behavior which makes it a suitable potential candidate for bone regeneration.

Effect of Bone Morphogenic Protein-2-Loaded Mesoporous Strontium Substitution Calcium Silicate/Recycled Fish Gelatin 3D Cell-Laden Scaffold for Bone Tissue Engineering

“…Among the numerous types of available biomaterials, ceramics are among the more prominent candidates for bone substitutes. Of which, calcium silicate (CS) is one of the more popular bioceramics due to its excellent biodegradation and osteoconduction ability as compared to the rest of the ceramics [8][9][10]. Recently, bone cements made up of calcium silicate received great attention from researchers as reports indicated that CS had the capability to release therapeutic ions such as Si and Ca ions [11].…”

Enhanced Proliferation and Differentiation of Human Mesenchymal Stem Cell-laden Recycled Fish Gelatin/Strontium Substitution Calcium Silicate 3D Scaffolds

“…Similarly, studies published by others indicated that traces of Si and Sr ions in the surrounding fluids were able to enhance cellular proliferation and differentiation. Therefore, we believe that FGSr scaffold was able to achieve higher levels of proliferation, differentiation and thus enhanced regeneration [3].…”

“…Sr-contained CS powder was synthesized using methods established by the previous report [3]. Analytically graded 65% calcium oxide (CaO, Sigma-Aldrich, St. Louis, MO, USA), 20% silicon dioxide (SiO2, Sigma-Aldrich), 10% strontium oxide (SrO, Sigma-Aldrich), and 5% alumina oxide (Al2O3, Sigma-Aldrich) was mixed evenly and sintered at 1400 • C for 2 h. After cooling to room temperature, the Sr-doped CS powder was wet grinding with 99.5% ethanol in a planetary ball mill (Retsch PM-100, Retsch GmbH, Germany) for 8 h. After this, the mixture was dried in an oven for 12 h.…”

“…Allograft is an alternative to bone repair; however, it is highly limited due to rejection and lack of availability. To solve this problem, researchers had attempted to develop novel biomaterials including ceramics, polymers and composites as an alternative choice for bone regeneration [3][4][5]. In order to promote bone healing, the material must be biocompatible, biodegradable and able to promote bone regeneration which mimics the distinctive property of natural bone [6].…”

The Calcium Channel Affect Osteogenic Differentiation of Mesenchymal Stem Cells on Strontium-Substituted Calcium Silicate/Poly-ε-Caprolactone Scaffold

“…In addition, several studies had been conducted which concluded that the addition of metallic ions into biomaterials was able to upregulate cellular activities and increase biological and anti-inflammatory capabilities [12,17,18]. In our previous study, we successfully incorporated strontium (Sr) into CS powder and fabricated 3D SrCS scaffold contained suitable porosity via 3D printing methods and such a SrCS biomaterial was also shown to enhance bone regeneration by increasing osteogenesis and angiogenesis [19,20].…”