Effects of fibrous collagen/CDHA/hUCS biocomposites on bone tissue regeneration

Decoupling the Effects of Collagen Alignment and Bioceramic Incorporation on Osteoblast Proliferation, Differentiation, and Mineralization

Biomimetic scaffolds provide the essential biophysical (e.g., surface topography, stiffness) and biochemical cues (e.g., composition) to guide cell morphology, proliferation, and differentiation. Although the effects of biomaterial-directed cues on cell response have been widely reported, few studies have sought to decouple these effects to better understand the interplay between the different physicochemical factors on tissue-specific cell function. Herein, beta-tricalcium phosphate (β-TCP) was incorporated into electrochemically aligned collagen (ELAC) and random collagen threads, and the individual and interactive effects of collagen alignment (i.e., biophysical) and bioceramic incorporation (i.e., biochemical) on osteoblast cell morphology, proliferation, differentiation, and mineralization were investigated. Results showed that collagen alignment in ELAC threads was retained upon β-TCP incorporation. Collagen alignment significantly improved (p < 0.05) the swelling capacity and stability of collagen threads, while β-TCP incorporation showed no such effects. Tensile tests revealed that β-TCP incorporation significantly decreased (p < 0.05) the strength and stiffness of ELAC threads. Significant increase (p < 0.05) in Saos-2 cell orientation and alkaline phosphatase (ALP) activity was observed on ELAC compared to random collagen threads indicating that aligned collagen serves as a key driving factor for osteogenesis. β-TCP incorporation into random collagen threads had no effect on Saos-2 cell function. On the other hand, presence of β-TCP significantly augmented (p < 0.05) Saos-2 cell metabolic activity, differentiation, and mineralization on ELAC threads. Together, these findings suggest that combining collagen alignment and β-TCP incorporation can create robust tissue-mimicking scaffolds for bone regeneration applications.

Bioactive Conjugated Polymer-Based Biodegradable 3D Bionic Scaffolds for Facilitating Bone Defect Repair

Bone defect regeneration is one of the great clinical challenges. Suitable bioactive composite scaffolds with high biocompatibility, robust new-bone formation capability and degradability are still required. This work designs and synthesizes an unprecedented bioactive conjugated polymer PT-C3 -NH2 , demonstrating low cytotoxicity, cell proliferation/migration-promoting effect, as well as inducing cell differentiation, namely regulating angiogenesis and osteogenesis to MC3T3-E1 cells. PT-C3 -NH2 is incorporated into polylactic acid-glycolic acid (PLGA) scaffolds, which is decorated with caffeic acid (CA)-modified gelatin (Gel), aiming to improve the surface water-wettability of PLGA and also facilitate to the linkage of conjugated polymer through catechol chemistry. A 3D composite scaffold PLGA@GC-PT is then generated. This scaffold demonstrates excellent bionic structures with pore size of 50-300 µm and feasible biodegradation ability. Moreover, it also exhibites robust osteogenic effect to promote osteoblast proliferation and differentiation in vitro, thus enabling the rapid regeneration of bone defects in vivo. Overall, this study provides a new bioactive factor and feasible fabrication approach of biomimetic scaffold for bone regeneration.

Collagen-Based Medical Devices for Regenerative Medicine and Tissue Engineering

Assisted reproductive technologies are key to solving the problems of aging and organ defects. Collagen is compatible with living tissues and has many different chemical properties; it has great potential for use in reproductive medicine and the engineering of reproductive tissues. It is a natural substance that has been used a lot in science and medicine. Collagen is a substance that can be obtained from many different animals. It can be made naturally or created using scientific methods. Using pure collagen has some drawbacks regarding its physical and chemical characteristics. Because of this, when collagen is processed in various ways, it can better meet the specific needs as a material for repairing tissues. In simpler terms, collagen can be used to help regenerate bones, cartilage, and skin. It can also be used in cardiovascular repair and other areas. There are different ways to process collagen, such as cross-linking it, making it more structured, adding minerals to it, or using it as a carrier for other substances. All of these methods help advance the field of tissue engineering. This review summarizes and discusses the current progress of collagen-based materials for reproductive medicine.

Biomaterials combined with ADSCs for bone tissue engineering: current advances and applications

In recent decades, bone tissue engineering, which is supported by scaffold, seed cells and bioactive molecules (BMs), has provided new hope and direction for treating bone defects. In terms of seed cells, compared to bone marrow mesenchymal stem cells, which were widely utilized in previous years, adipose-derived stem cells (ADSCs) are becoming increasingly favored by researchers due to their abundant sources, easy availability and multi-differentiation potentials. However, there is no systematic theoretical basis for selecting appropriate biomaterials loaded with ADSCs. In this review, the regulatory effects of various biomaterials on the behavior of ADSCs are summarized from four perspectives, including biocompatibility, inflammation regulation, angiogenesis and osteogenesis, to illustrate the potential of combining various materials with ADSCs for the treatment of bone defects. In addition, we conclude the influence of additional application of various BMs on the bone repair effect of ADSCs, in order to provide more evidences and support for the selection or preparation of suitable biomaterials and BMs to work with ADSCs. More importantly, the associated clinical case reports and experiments are generalized to provide additional ideas for the clinical transformation and application of bone tissue engineering loaded with ADSCs.

Accelerating bone regeneration using poly(lactic-co-glycolic acid)/hydroxyapatite scaffolds containing duck feet-derived collagen

Collagen, with low antigenicity and excellent cell adhesion, is a biomaterial mainly used for regenerating bone, cartilage, and skin, owing to its biocompatibility and biodegradability. Results from a previous study confirmed that a scaffold mixed with duck feet-derived collagen (DC) and Poly(lactic-co-glycolic acid) (PLGA) reduced inflammatory reaction and increased bone regeneration. To develop an optimal bone substitute we included hydroxyapatite (HAp), a key osteoconductive material, in a DC and PLGA mixture. We fabricated 0, 10, 20, 40, 60, and 80 wt% DC/PLGA/HAp scaffolds and studied their potential for bone tissue engineering. Characteristic analysis of the scaffold and seeding of rabbit bone marrow mesenchymal stem cells (rBMSCs) on the scaffold were conducted to investigate cell proliferation, osteogenic differentiation, and bone formation. We confirmed that increasing DC concentration not only improved the compressive strength of the DC/PLGA/HAp scaffold but also cell proliferation and osteogenic differentiation. It was found through comparison with previous studies that including HAp in the scaffold also promotes osteogenic differentiation. Our study thus shows through in vivo results that the 80 wt% DC/PLGA/HAp scaffold promotes bone mineralization and collagen deposition while reducing the inflammatory response. Hence, 80 wt% DC/PLGA/HAp has excellent potential as a biomaterial for bone regeneration applications.

A comparative study of bone bioactivity and osteogenic potential of different bioceramics in methacrylated collagen hydrogels

Biomimetic scaffolds composed of bioactive ceramic-based materials incorporated within a polymeric framework have shown immense promise for use in bone tissue engineering (BTE) applications. However, studies on direct comparison of the efficacy of different bioceramics on bone bioactivity and osteogenic differentiation are lacking. Herein, we performed an in vitro direct comparison of three different bioceramics-Bioglass 45S5 (BG), Laponite XLG (LAP), and β-Tricalcium Phosphate (TCP)-on the physical properties and bone bioactivity of methacrylated collagen (CMA) hydrogels (10% w/w bioceramic:CMA). In addition, human MSCs (hMSCs) were encapsulated in bioceramic-laden CMA hydrogels and the effect of different bioceramics on osteogenic differentiation of hMSCs was investigated in two different culture medium-osteoconductive (without dexamethasone [DEX]) and osteoinductive (with DEX). Results showed that the stability of CMA hydrogels was maintained upon bioceramic addition. Compression testing revealed that BG incorporation significantly decreased (p < 0.05) the modulus of photochemically crosslinked CMA hydrogels. Incubation of TCP-CMA and LAP-CMA hydrogels in simulated body fluid showed deposition of hydroxycarbonate apatite layer on the surface indicating that these hydrogels may be more bone bioactive than BG-CMA and CMA only hydrogels. Cell cytoskeleton staining results showed greater cell spreading in TCP-CMA hydrogels. Furthermore, TCP incorporation significantly increased alkaline phosphatase activity (ALP; p < 0.05) in hMSCs. Together, these results indicate that TCP has superior osteogenic potential compared with BG and LAP and hence should be considered as a bioceramic of preferred choice for use in the biomimetic design of cell-laden hydrogels for BTE applications.

Mastoid obliteration and external auditory canal reconstruction using 3D printed bioactive glass S53P4 /polycaprolactone scaffold loaded with bone morphogenetic protein-2: A simulation clinical study in rabbits

INTRODUCTION

The lack of good prosthetic materials and objective standards has limited the promotion of mastoid obliteration and external auditory canal reconstruction, and the quality of the surgery varies. In this study, bioactive glass S53P4 (S53P4), the most popular artificial prosthetic material, was modified and combined with polycaprolactone (PCL) and bone morphogenetic protein-2 (BMP-2) to produce an individualized biological scaffold using 3D printing technology to explore a better material and method for mastoid obliteration and external auditory canal reconstruction.

METHODS

3D-printed S53P4/PCL scaffolds were fabricated from 3D reconstruction data of bone defect areas in New Zealand rabbits simulating "Canal Wall Down Mastoidectomy". The water absorption, swelling rate, porosity, and Young's modulus of the scaffold were measured, and the morphology and pore size of the scaffold were observed using scanning electron microscopy. The cytotoxicity of the S53P4/PCL scaffolds was detected using the CCK8 assay, and the in vitro antibacterial activity of the S53P4/PCL scaffolds was detected using the inhibition circle method. The BMP-2-loaded S53P4/PCL scaffolds were prepared using the drop-in lyophilization method and implanted into animal models. The biocompatibility, osteogenic activity, and external auditory canal repair of the scaffolds were observed using endoscopy, micro-CT, and histological examination.

RESULTS

The S53P4/PCL scaffold was highly compatible with the defective area of the animal model, and its physicochemical properties met the requirements of bone tissue engineering. In vitro experiments showed that the S53P4/PCL scaffold was non-cytotoxic and exhibited better antibacterial activity than the same volume of the S53P4 powder. In vivo experiments showed that the S53P4/PCL scaffold had good biocompatibility and osteogenic activity, and could effectively repair bone defects and reconstruct the normal morphology of the external auditory canal in animal models. Furthermore, its osteogenic activity and repair ability were significantly improved after loading with BMP-2.

CONCLUSIONS

The 3D printed S53P4/PCL scaffold has great potential for clinical mastoid obliteration and external auditory canal reconstruction.

Design Strategies and Biomimetic Approaches for Calcium Phosphate Scaffolds in Bone Tissue Regeneration

Bone is a complex biologic tissue, which is extremely relevant for various physiological functions, in addition to movement, organ protection, and weight bearing. The repair of critical size bone defects is a still unmet clinical need, and over the past decades, material scientists have been expending efforts to find effective technological solutions, based on the use of scaffolds. In this context, biomimetics which is intended as the ability of a scaffold to reproduce compositional and structural features of the host tissues, is increasingly considered as a guide for this purpose. However, the achievement of implants that mimic the very complex bone composition, multi-scale structure, and mechanics is still an open challenge. Indeed, despite the fact that calcium phosphates are widely recognized as elective biomaterials to fabricate regenerative bone scaffolds, their processing into 3D devices with suitable cell-instructing features is still prevented by insurmountable drawbacks. With respect to biomaterials science, new approaches maybe conceived to gain ground and promise for a substantial leap forward in this field. The present review provides an overview of physicochemical and structural features of bone tissue that are responsible for its biologic behavior. Moreover, relevant and recent technological approaches, also inspired by natural processes and structures, are described, which can be considered as a leverage for future development of next generation bioactive medical devices.

Effect of Hydroxyapatite Coating by Er: YAG Pulsed Laser Deposition on the Bone Formation Efficacy by Polycaprolactone Porous Scaffold

Composite scaffolds obtained by the combination of biodegradable porous scaffolds and hydroxyapatite with bone regeneration potential are feasible materials for bone tissue engineering. However, most composite scaffolds have been fabricated by complicated procedures or under thermally harsh conditions. We have previously demonstrated that hydroxyapatite coating onto various substrates under a thermally mild condition was achieved by erbium-doped yttrium aluminum garnet (Er: YAG) pulsed laser deposition (PLD). The purpose of this study was to prepare a polycaprolactone (PCL) porous scaffold coated with the hydroxyapatite by the Er: YAG-PLD method. Hydroxyapatite coating by the Er: YAG-PLD method was confirmed by morphology, crystallographic analysis, and surface chemical characterization studies. When cultured on PCL porous scaffold coated with hydroxyapatite, rat bone marrow-derived mesenchymal stem cells adhered, spread, and proliferated well. The micro-CT and staining analyses after the implantation of scaffold into the critical-sized calvaria bone defect in rats indicate that PCL porous scaffold coated with hydroxyapatite demonstrates accelerated and widespread bone formation. In conclusion, PCL porous scaffold coated with hydroxyapatite obtained by the Er: YAG-PLD method is a promising material in bone tissue engineering.

Mechanical, Structural, and Biological Properties of Chitosan/Hydroxyapatite/Silica Composites for Bone Tissue Engineering

The aim of this work was to fabricate novel bioactive composites based on chitosan and non-organic silica, reinforced with calcium β-glycerophosphate (Ca-GP), sodium β-glycerophosphate pentahydrate (Na-GP), and hydroxyapatite powder (HAp) in a range of concentrations using the sol–gel method. The effect of HAp, Na-GP, and Ca-GP contents on the mechanical properties, i.e., Young’s modulus, compressive strength, and yield strain, of hybrid composites was analyzed. The microstructure of the materials obtained was visualized by SEM. Moreover, the molecular interactions according to FTIR analysis and biocompatibility of composites obtained were examined. The CS/Si/HAp/Ca-GP developed from all composites analyzed was characterized by the well-developed surface of pores of two sizes: large ones of 100 μm and many smaller pores below 10 µm, the behavior of which positively influenced cell proliferation and growth, as well as compressive strength in a range of 0.3 to 10 MPa, Young’s modulus from 5.2 to 100 MPa, and volumetric shrinkage below 60%. This proved to be a promising composite for applications in tissue engineering, e.g., filling small bone defects.