Microsphere-based scaffolds encapsulating tricalcium phosphate and hydroxyapatite for bone regeneration

Abstract

Bioceramic mixtures of tricalcium phosphate (TCP) and hydroxyapatite (HAp) are widely used for bone regeneration because of their excellent cytocompatibility, osteoconduction, and osteoinduction. Therefore, we hypothesized that incorporation of a mixture of TCP and HAp in microsphere-based scaffolds would enhance osteogenesis of rat bone marrow stromal cells (rBMSCs) compared to a positive control of scaffolds with encapsulated bone-morphogenic protein-2 (BMP-2). Poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds encapsulating TCP and HAp mixtures in two different ratios (7:3 and 1:1) were fabricated with the same net ceramic content (30 wt%) to evaluate how incorporation of these ceramic mixtures would affect the osteogenesis in rBMSCs. Encapsulation of TCP/HAp mixtures impacted microsphere morphologies and the compressive moduli of the scaffolds. Additionally, TCP/HAp mixtures enhanced the end-point secretion of extracellular matrix (ECM) components relevant to bone tissue compared to the “blank” (PLGA-only) microsphere-based scaffolds as evidenced by the biochemical, gene expression, histology, and immunohistochemical characterization. Moreover, the TCP/HAp mixture groups even surpassed the BMP-2 positive control group in some instances in terms of matrix synthesis and gene expression. Lastly, gene expression data suggested that the rBMSCs responded differently to different TCP/HAp ratios presented to them. Altogether, it can be concluded that TCP/HAp mixtures stimulated the differentiation of rBMSCs toward an osteoblastic phenotype, and therefore may be beneficial in gradient microsphere-based scaffolds for osteochondral regeneration.

Applications of Carbon Nanotubes in Bone Tissue Regeneration and Engineering: Superiority, Concerns, Current Advancements, and Prospects

“…Tricalcium phosphate has a similar chemical composition and structural and elastic moduli to HA, known as another important calcium phosphate-based biomaterial. Beta-tricalcium phosphate (β-TCP) not only possesses good biocompatibility and osteoconductivity, but also shows in vivo resorbability during the bone growth, making it an ideal candidate as a biomaterial for bone tissue engineering [151,152,153]. Mirjalili et al [154] successfully synthesized a β-TCP–CNT nanocomposite by solution precipitation method.…”

Gelatin/Nanohyroxyapatite Cryogel Embedded Poly(lactic-co-glycolic Acid)/Nanohydroxyapatite Microsphere Hybrid Scaffolds for Simultaneous Bone Regeneration and Load-Bearing

“…At the same time, nHAP-incorporated PLGA microspheres are not only osteo-conductive/inductive, but also stable constructs that can withstand load-bearing in bone, to a certain extent. PLGA-based microsphere scaffolds are reported to be good substitute materials in bone tissue engineering when used as a composite material with nHAP or tricalcium phosphate [23]. In short, we intend to develop a hybrid bone tissue engineering scaffold with both load-bearing and bone regeneration capabilities using a high-strength PLGA-nHAP microsphere cavity fitted with biomimetic gelatin-nHAP cryogel.…”

Core–Shell Bioactive Ceramic Robocasting: Tuning Component Distribution Beneficial for Highly Efficient Alveolar Bone Regeneration and Repair

“…In contrast, TCP with intrinsic osteoconductivity but significantly low degradation, is usually chosen to adjust the performance of composite scaffolds. Unfortunately, the conventional mechanical mixing approach usually fails to tailor the physicochemical and biological properties of the TCP/CSi composites or even compromise them. ,, In this aspect, core–shell TCP@CSi-Mg4 design can adjust biodegradation behaviors of the scaffolds precisely by distributing bioceramic components with different biodegradation rates in the core and shell layers.…”