Tricalcium Phosphate Sol-Incorporated Poly(ε-caprolactone) Membrane with Improved Mechanical and Osteoinductive Activity as an Artificial Periosteum

Multipotent Mesenchymal Cells Homing and Differentiation on Poly(ε-caprolactone) Blended with 20% Tricalcium Phosphate and Polylactic Acid Incorporating 10% Hydroxyapatite 3D-Printed Scaffolds via a Commercial Fused Deposition Modeling 3D Device

As highlighted by the 'Global Burden of Disease Study 2019' conducted by the World Health Organization, ensuring fair access to medical care through affordable and targeted treatments remains crucial for an ethical global healthcare system. Given the escalating demand for advanced and urgently needed solutions in regenerative bone procedures, the critical role of biopolymers emerges as a paramount necessity, offering a groundbreaking avenue to address pressing medical needs and revolutionize the landscape of bone regeneration therapies. Polymers emerge as excellent solutions due to their versatility, making them reliable materials for 3D printing. The development and widespread adoption of this technology would impact production costs and enhance access to related healthcare services. For instance, in dentistry, the use of commercial polymers blended with β-tricalcium phosphate (TCP) is driven by the need to print a standardized product with osteoconductive features. However, modernization is required to bridge the gap between biomaterial innovation and the ability to print them through commercial printing devices. Here we showed, for the first time, the metabolic behavior and the lineage commitment of bone marrow-derived multipotent mesenchymal cells (MSCs) on the 3D-printed substrates poly(e-caprolactone) combined with 20% tricalcium phosphate (PCL + 20% β-TCP) and L-polylactic acid (PLLA) combined with 10% hydroxyapatite (PLLA + 10% HA). Although there are limitations in printing additive-enriched polymers with a predictable and short half-life, the tested 3D-printed biomaterials were highly efficient in supporting osteoinductivity. Indeed, considering different temporal sequences, both 3D-printed biomaterials resulted as optimal scaffolds for MSCs' commitment toward mature bone cells. Of interest, PLLA + 10% HA substrates hold the confirmation as the finest material for osteoinduction of MSCs.

Three-dimensional bioprinted BMSCs-laden highly adhesive artificial periosteum containing gelatin-dopamine and graphene oxide nanosheets promoting bone defect repair

The periosteum is a connective tissue membrane adhering to the surface of bone tissue that primarily provides nutrients and regulates osteogenesis during bone development and injury healing. However, building an artificial periosteum with good adhesion properties and satisfactory osteogenesis for bone defect repair remains a challenge, especially using three-dimensional (3D) bioprinting. In this study, dopamine was first grafted onto the molecular chain of gelatin usingN-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride andN-hydroxysuccinimide (NHS) to activate the carboxyl group and produce modified gelatin-dopamine (GelDA). Next, a methacrylated gelatin, methacrylated silk fibroin, GelDA, and graphene oxide nanosheet composite bioink loaded with bone marrow mesenchymal stem cells was prepared and used for bioprinting. The physicochemical properties, biocompatibility, and osteogenic roles of the bioink and 3D bioprinted artificial periosteum were then systematically evaluated. The results showed that the developed bioink showed good thermosensitivity and printability and could be used to build 3D bioprinted artificial periosteum with satisfactory cell viability and high adhesion. Finally, the 3D bioprinted artificial periosteum could effectively enhance osteogenesis bothin vitroandin vivo. Thus, the developed 3D bioprinted artificial periosteum can prompt new bone formation and provides a promising strategy for bone defect repair.

Drug-Loaded and Anisotropic Wood-Derived Hydrogel Periosteum with Super Antibacterial, Anti-Inflammatory, and Osteogenic Activities

Current artificial periostea mainly focus on osteogenic activity but overlook structural and mechanical anisotropy, as well as the importance of antibacterial and anti-inflammatory properties. Here, inspired by the anisotropic structure of wood, the delignified wood (named white wood, WW) with a porous and highly oriented cellulose fiber skeleton was obtained, which was further filled with polyvinyl alcohol (PVA) hydrogel loaded with curcumin (Cur) and phytic acid (PA). The prepared wood-derived hydrogel composite membranes can not only exhibit an obvious anisotropic structure and good mechanical properties but also sustainably release loaded drugs to obtain long-term biological activities. Creatively, PA can effectively improve the bioavailability of Cur; more importantly, Cur and PA play an obvious synergistic effect in antibacterial, anti-inflammatory, and osteogenic activities. Compared with the wood-derived hydrogel composite membranes without drug loading, as well as loaded with Cur or PA only, these loaded with Cur and PA are significantly more conducive to inhibiting the growth of bacteria and inflammatory response and facilitating the adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells. This kind of anisotropic wood-derived hydrogel composite membrane with fantastic antibacterial, anti-inflammatory, and osteogenic activities is expected to be ideal artificial periostea.

Poly (Butylene Succinate)/Silicon Nitride Nanocomposite with Optimized Physicochemical Properties, Biocompatibility, Degradability, and Osteogenesis for Cranial Bone Repair

Congenital disease, tumors, infections, and trauma are the main reasons for cranial bone defects. Herein, poly (butylene succinate) (PB)/silicon nitride (Si₃N₄) nanocomposites (PSC) with Si3N4 content of 15 w% (PSC15) and 30 w% (PSC30) were fabricated for cranial bone repair. Compared with PB, the compressive strength, hydrophilicity, surface roughness, and protein absorption of nanocomposites were increased with the increase in Si₃N₄ content (from 15 w% to 30 w%). Furthermore, the cell adhesion, multiplication, and osteoblastic differentiation on PSC were significantly enhanced with the Si₃N₄ content increasing in vitro. PSC30 exhibited optimized physicochemical properties (compressive strength, surface roughness, hydrophilicity, and protein adsorption) and cytocompatibility. The m-CT and histological results displayed that the new bone formation for SPC30 obviously increased compared with PB, and PSC30 displayed proper degradability (75.3 w% at 12 weeks) and was gradually replaced by new bone tissue in vivo. The addition of Si₃N₄ into PB not only optimized the surface performances of PSC but also improved the degradability of PSC, which led to the release of Si ions and a weak alkaline environment that significantly promoted cell response and tissue regeneration. In short, the enhancements of cellular responses and bone regeneration of PSC30 were attributed to the synergism of the optimized surface performances and slow release of Si ion, and PSC30 were better than PB. Accordingly, PSC30, with good biocompatibility and degradability, displayed a promising and huge potential for cranial bone construction.

Small Intestinal Submucosa Biomimetic Periosteum Promotes Bone Regeneration

Background: Critical bone defects are a significant problem in clinics. The periosteum plays a vital role in bone regeneration. A tissue-engineered periosteum (TEP) has received increasing attention as a novel strategy for bone defect repairs. Methods: In this experiment, a biomimetic periosteum was fabricated by using coaxial electrospinning technology with decellularized porcine small intestinal submucosa (SIS) as the shell and polycaprolactone (PCL) as the core. In vitro, the effects of the biomimetic periosteum on Schwann cells, vascular endothelial cells, and bone marrow mesenchymal stem cells were detected by a scratch test, an EdU, a tube-forming test, and an osteogenesis test. In vivo, we used HE staining to evaluate the effect of the biomimetic periosteum on bone regeneration. Results: In vitro experiments showed that the biomimetic periosteum could significantly promote the formation of angiogenesis, osteogenesis, and repaired Schwann cells (SCs). In vivo experiments showed that the biomimetic periosteum could promote the repair of bone defects. Conclusions: The biomimetic periosteum could simulate the structural function of the periosteum and promote bone repair. This strategy may provide a promising method for the clinical treatment of skull bone defects.

Functionalization of Electrospun Nanofiber for Bone Tissue Engineering

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure of the extracellular matrix (ECM). Their unique characteristics are: larger surface areas, porosity and processability; these make them ideal candidates for bone-tissue engineering. This review briefly introduces bone-tissue engineering and summarizes the materials and methods for electrospining. More importantly, how to functionalize electrospun nanofibers to make them more conducive for bone regeneration is highlighted. Finally, the existing deficiencies of functionalized electrospun nanofibers for promoting osteogenesis are proposed. Such a summary can lay the foundation for the clinical practice of functionalized electrospun nanofibers.

Effects of integrated bioceramic and uniaxial drawing on mechanically-enhanced fibrogenesis for bionic periosteum engineering

Periosteum is clinically required for the management of large bone defects. Attempts to exploit the periosteum's participation in bone healing, however, have rarely featured biological and mechanical complexity for the scaffolds relevant to translational medicine. In this regard, we report engineering of bioinspired periosteum with co-delivery of ionic and geometry cues. The scaffold demonstrated microsheet-like fibre morphology and was developed based on bioresorbable poly(-caprolactone) and bioactive copper-doped tricalcium phosphate (Cu-TCP). A coordinated interaction was found between the effects of Cu-TCP addition and uniaxial drawing, leading to tunable fibrogenesis for different fibre morphologies, organisation, and surface wettability. The coordination resulted in significant enhancements in Young's Modulus, yield stress and ultimate stress along fibrous alignment, without causing reductions across fibres. This demonstrated mechanical anisotropy of the scaffold similar to natural periosteum, and seeding with mouse calvarial preosteoblasts, the scaffold supported cell alignment with deposition of CaP-like nodules and extracellular matrix. This work provides new insights on periosteum engineering with osteo-related composite fibres. The artificial periosteum can be used in clinical settings to facilitate repair of large bone defects.

Progress on Biomimetic Mineralization and Materials for Hard Tissue Regeneration

Biomineralization is a process in which natural organisms regulate the crystal growth of inorganic minerals, resulting in hierarchical structured biominerals with excellent properties. Typical biominerals in the human body are the bones and teeth, and damage to these hard tissues directly affect our daily lives. The repair of bones and teeth in a biomimetic way, either by using a biomimetic mineralization strategy or biomimetic materials, is the key for hard tissue regeneration. In this review, we briefly introduce the structure of bone and tooth, and highlight the fundamental role of collagen mineralization in tissue repair. The recent progress on intra-/extrafibrillar collagen mineralization by a biomimetic strategy or materials is presented, and their potential for tissue regeneration is discussed. Then, recent achievements on bone and tooth repair are summarized, and these works are discussed in the view of materials science and biological science, providing a broader vision for the future research of hard tissue repair techniques. Lastly, recent progress on hard tissue regeneration is concluded, and existing problems and future directions are prospected.

Hierarchical Nanostructured Electrospun Membrane with Periosteum-Mimic Microenvironment for Enhanced Bone Regeneration

An ideal periosteum substitute should be able to mimic the periosteum microenvironment that continuously provides growth factors, recruits osteoblasts, and subsequent extracellular matrix (ECM) mineralization to accelerate bone regeneration. Here, a calcium-binding peptide-loaded poly(ε-caprolactone) (PCL) electrospun membrane modified by the shish-kebab structure that can mimic the periosteum microenvironment was developed as a bionic periosteum. The calcium-binding peptide formed by the negatively charged heptaglutamate domain (E7) in the E7-BMP-2 with calcium ion in the tricalcium phosphate sol (TCP sol) through electrostatic chelation not only extended the release cycle of E7-BMP-2 but also promoted the biomineralization of the bionic periosteum. Cell experiments showed that the bionic periosteum could significantly improve the osteogenic differentiation of the rat-bone marrow-derived mesenchymal stem cells (rBMSCs) through both chemical composition and physical structure. The in vivo evaluation of the bionic periosteum confirmed the inherent osteogenesis of this periosteum microenvironment, which could promote the regeneration of vascularized bone tissue. Therefore, the hierarchical nanostructured electrospun membrane with periosteum-mimic microenvironment is a promising periosteum substitute for the treatment of bone defects.

Electropsun Polycaprolactone Fibres in Bone Tissue Engineering: A Review

Regeneration of bone tissue requires novel load bearing, biocompatible materials that support adhesion, spreading, proliferation, differentiation, mineralization, ECM production and maturation of bone-forming cells. Polycaprolactone (PCL) has many advantages as a biomaterial for scaffold production including tuneable biodegradation, relatively high mechanical toughness at physiological temperature. Electrospinning produces nanofibrous porous matrices that mimic many properties of natural tissue extracellular matrix with regard to surface area, porosity and fibre alignment. The biocompatibility and hydrophilicity of PCL nanofibres can be improved by combining PCL with other biomaterials to form composite scaffolds for bone regeneration. This work reviews the most recent research on synthesis, characterization and cellular response to nanofibrous PCL scaffolds and the composites of PCL with other natural and synthetic materials for bone tissue engineering.