A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process

Fabrication Strategies for Bioceramic Scaffolds in Bone Tissue Engineering with Generative Design Applications

The aim of this study is to provide an overview of the current state-of-the-art in the fabrication of bioceramic scaffolds for bone tissue engineering, with an emphasis on the use of three-dimensional (3D) technologies coupled with generative design principles. The field of modern medicine has witnessed remarkable advancements and continuous innovation in recent decades, driven by a relentless desire to improve patient outcomes and quality of life. Central to this progress is the field of tissue engineering, which holds immense promise for regenerative medicine applications. Scaffolds are integral to tissue engineering and serve as 3D frameworks that support cell attachment, proliferation, and differentiation. A wide array of materials has been explored for the fabrication of scaffolds, including bioceramics (i.e., hydroxyapatite, beta-tricalcium phosphate, bioglasses) and bioceramic-polymer composites, each offering unique properties and functionalities tailored to specific applications. Several fabrication methods, such as thermal-induced phase separation, electrospinning, freeze-drying, gas foaming, particle leaching/solvent casting, fused deposition modeling, 3D printing, stereolithography and selective laser sintering, will be introduced and thoroughly analyzed and discussed from the point of view of their unique characteristics, which have proven invaluable for obtaining bioceramic scaffolds. Moreover, by highlighting the important role of generative design in scaffold optimization, this review seeks to pave the way for the development of innovative strategies and personalized solutions to address significant gaps in the current literature, mainly related to complex bone defects in bone tissue engineering.

3D-Printed Polycaprolactone-Based Containing Calcium Zirconium Silicate: Bioactive Scaffold for Accelerating Bone Regeneration

There is an essential clinical need to develop rapid process scaffolds to repair bone defects. The current research presented the development of calcium zirconium silicate/polycaprolactone for bone tissue engineering utilising melt extrusion-based 3D printing. Calcium zirconium silicate (CZS) nanoparticles were added to polycaprolactone (PCL) porous scaffolds to enhance their biological and mechanical properties, while the resulting properties were studied extensively. No significant difference was found in the melting point of the samples, while the crystallisation temperature points of the samples containing bioceramic increased from 36.1 to 40.2 °C. Thermal degradation commenced around 350 °C for all materials. According to our results, increasing the CZS content from 0 to 40 wt.% (PC40) in porous scaffolds (porosity about 55-62%) improved the compressive strength from 2.8 to 10.9 MPa. Furthermore, apatite formation ability in SBF solution increased significantly by enhancing the CZS percentage. According to MTT test results, the viability of MG63 cells improved remarkably (~29%) in PC40 compared to pure PCL. These findings suggest that a 3D-printed PCL/CZS composite scaffold can be fabricated successfully and shows great potential as an implantable material for bone tissue engineering applications.

Advances in natural and synthetic macromolecules with stem cells and extracellular vesicles for orthopedic disease treatment

Serious orthopedic disorders resulting from myriad diseases and impairments continue to pose a considerable challenge to contemporary clinical care. Owing to its limited regenerative capacity, achieving complete bone tissue regeneration and complete functional restoration has proven challenging with existing treatments. By virtue of cellular regenerative and paracrine pathways, stem cells are extensively utilized in the restoration and regeneration of bone tissue; however, low survival and retention after transplantation severely limit their therapeutic effect. Meanwhile, biomolecule materials provide a delivery platform that improves stem cell survival, increases retention, and enhances therapeutic efficacy. In this review, we present the basic concepts of stem cells and extracellular vesicles from different sources, emphasizing the importance of using appropriate expansion methods and modification strategies. We then review different types of biomolecule materials, focusing on their design strategies. Moreover, we summarize several forms of biomaterial preparation and application strategies as well as current research on biomacromolecule materials loaded with stem cells and extracellular vesicles. Finally, we present the challenges currently impeding their clinical application for the treatment of orthopedic diseases. The article aims to provide researchers with new insights for subsequent investigations.

Investigation of background, novelty and recent advance of iron (II,III) oxide- loaded on 3D polymer based scaffolds as regenerative implant for bone tissue engineering: A review

Bone tissue engineering had crucial role in the bone defects regeneration, particularly when allograft and autograft procedures have limitations. In this regard, different types of scaffolds are used in tissue regeneration as fundamental tools. In recent years, magnetic scaffolds show promising applications in different biomedical applications (in vitro and in vivo). As superparamagnetic materials are widely considered to be among the most attractive biomaterials in tissue engineering, due to long-range stability and superior bioactivity, therefore, magnetic implants shows angiogenesis, osteoconduction, and osteoinduction features when they are combined with biomaterials. Furthermore, these scaffolds can be coupled with a magnetic field to enhance their regenerative potential. In addition, magnetic scaffolds can be composed of various combinations of magnetic biomaterials and polymers using different methods to improve the magnetic, biocompatibility, thermal, and mechanical properties of the scaffolds. This review article aims to explain the use of magnetic biomaterials such as iron (II,III) oxide (Fe2O3 and Fe3O4) in detail. So it will cover the research background of magnetic scaffolds, the novelty of using these magnetic implants in tissue engineering, and provides a future perspective on regenerative implants.

Crosslinking of a polycaprolactone/tourmaline scaffold by sodium stearate with improved mechanical strength and bioactivity

Although polycaprolactone (PCL) matrix composites have been extensively studied, the weak interface with nanofillers limits their further applications in bone tissue engineering. Herein, this study has designed a porous bone scaffold model using the triply periodic minimal surfaces (TPMS), and the optimal porosity was determined by comparing the mechanical properties. A sodium stearate-modified PCL/tourmaline (PCL/TM) composite scaffold with a strong interfacial effect was prepared by selective laser sintering technology. Wherein, sodium stearate acts as a bridge to improve the interaction between TM and PCL interface, while promoting its uniform dispersion. The results showed that the PCL/3% modified TM specimens exhibit the optimum mechanical properties, and their ultimate tensile and compressive strength increases by 21.8% and 32.1%, respectively, compared with pure PCL. The factors of mechanical enhancement of composite scaffolds can be elaborated from the construction of interface bridges. On the one hand, the carboxyl group at one end of sodium stearate will interact with the hydroxyl group on the surface of TM to enhance interfacial adsorption by forming ionic bonds and hydrogen bonds. On the other hand, the hydrophobic long chain at the other end of sodium stearate is universally compatible with hydrophobic PCL, thereby improving the dispersion of TM. These characteristics make the PCL/TM composite scaffold a valuable reference for its application in bone tissue engineering.

A Review of Biomimetic and Biodegradable Magnetic Scaffolds for Bone Tissue Engineering and Oncology

Bone defects characterized by limited regenerative properties are considered a priority in surgical practice, as they are associated with reduced quality of life and high costs. In bone tissue engineering, different types of scaffolds are used. These implants represent structures with well-established properties that play an important role as delivery vectors or cellular systems for cells, growth factors, bioactive molecules, chemical compounds, and drugs. The scaffold must provide a microenvironment with increased regenerative potential at the damage site. Magnetic nanoparticles are linked to an intrinsic magnetic field, and when they are incorporated into biomimetic scaffold structures, they can sustain osteoconduction, osteoinduction, and angiogenesis. Some studies have shown that combining ferromagnetic or superparamagnetic nanoparticles and external stimuli such as an electromagnetic field or laser light can enhance osteogenesis and angiogenesis and even lead to cancer cell death. These therapies are based on in vitro and in vivo studies and could be included in clinical trials for large bone defect regeneration and cancer treatments in the near future. We highlight the scaffolds' main attributes and focus on natural and synthetic polymeric biomaterials combined with magnetic nanoparticles and their production methods. Then, we underline the structural and morphological aspects of the magnetic scaffolds and their mechanical, thermal, and magnetic properties. Great attention is devoted to the magnetic field effects on bone cells, biocompatibility, and osteogenic impact of the polymeric scaffolds reinforced with magnetic nanoparticles. We explain the biological processes activated due to magnetic particles' presence and underline their possible toxic effects. We present some studies regarding animal tests and potential clinical applications of magnetic polymeric scaffolds.

Colonization versus encapsulation in cell-laden materials design: porosity and process biocompatibility determine cellularization pathways

Seeding materials with living cells has been-and still is-one of the most promising approaches to reproduce the complexity and the functionality of living matter. The strategies to associate living cells with materials are limited to cell encapsulation and colonization, however, the requirements for these two approaches have been seldom discussed systematically. Here we propose a simple two-dimensional map based on materials' pore size and the cytocompatibility of their fabrication process to draw, for the first time, a guide to building cellularized materials. We believe this approach may serve as a straightforward guideline to design new, more relevant materials, able to seize the complexity and the function of biological materials. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

Fabrication of three dimensional bioactive Sr2+ substituted apatite scaffolds by gel-casting technique for hard tissue regeneration

This study aimed to fabricate three-dimensional (3D) bioactive Sr²⁺ -substituted apatite (Sr-HAP) scaffolds prepared by gel-casting with polymer sponge infiltration technique. 3D Sr-HAP scaffolds were prepared as engineering constructs with interconnected porous structure with a pore size of 200-600 μm ranging from a 10 × 10 × 6 mm size was designed. The characterization of X-ray diffraction, field emission scanning electron microscopy, and energy dispersion spectroscopy was utilized in order to evaluate the crystalline phase, structure, and morphology in the interconnected porous of the synthesized Sr-HAP scaffold. The bioactive and biocompatible of the resultant Sr-HAP scaffolds were analyzed by using simulated body fluid solution. Furthermore, the cytotoxicity and proliferation of MG-63 cell lines on the scaffolds were examined in 24 h culture. Furthermore, in vivo experiments demonstrated that the tibia bone defect with 4 mm diameter in rabbits was successfully healed by Sr-HAP porous scaffold after 45 days implantation. The histological images indicated the improved cell proliferation and new bone formation occurred in the porous scaffold treated group. The results indicated that the fabricated Sr-HAP scaffold is a promising capacity to infuse bone regeneration and promote in vivo tissue repair.

Applications of Biomaterials in 3D Cell Culture and Contributions of 3D Cell Culture to Drug Development and Basic Biomedical Research

The process of evaluating the efficacy and toxicity of drugs is important in the production of new drugs to treat diseases. Testing in humans is the most accurate method, but there are technical and ethical limitations. To overcome these limitations, various models have been developed in which responses to various external stimuli can be observed to help guide future trials. In particular, three-dimensional (3D) cell culture has a great advantage in simulating the physical and biological functions of tissues in the human body. This article reviews the biomaterials currently used to improve cellular functions in 3D culture and the contributions of 3D culture to cancer research, stem cell culture and drug and toxicity screening.

Modeling the Mechanobiology of Cancer Cell Migration Using 3D Biomimetic Hydrogels

Understanding how cancer cells migrate, and how this migration is affected by the mechanical and chemical composition of the extracellular matrix (ECM) is critical to investigate and possibly interfere with the metastatic process, which is responsible for most cancer-related deaths. In this article we review the state of the art about the use of hydrogel-based three-dimensional (3D) scaffolds as artificial platforms to model the mechanobiology of cancer cell migration. We start by briefly reviewing the concept and composition of the extracellular matrix (ECM) and the materials commonly used to recreate the cancerous ECM. Then we summarize the most relevant knowledge about the mechanobiology of cancer cell migration that has been obtained using 3D hydrogel scaffolds, and relate those discoveries to what has been observed in the clinical management of solid tumors. Finally, we review some recent methodological developments, specifically the use of novel bioprinting techniques and microfluidics to create realistic hydrogel-based models of the cancer ECM, and some of their applications in the context of the study of cancer cell migration.

Fabrication of nanochitosan incorporated polypyrrole/alginate conducting scaffold for neural tissue engineering

The utilization of conductive polymers for fabrication of neural scaffolds have attracted much interest because of providing a microenvironment which can imitate nerve tissues. In this study, polypyrrole (PPy)-alginate (Alg) composites were prepared using different percentages of alginate and pyrrole by oxidative polymerization method using FeCl3 as an oxidant and electrical conductivity of composites were measured by four probe method. In addition, chitosan-based nanoparticles were synthesized by ionic gelation method and after characterization merged into PPy-Alg composite in order to fabricate a conductive, hydrophilic, processable and stable scaffold. Physiochemical characterization of nanochitosan/PPy-Alg scaffold such as electrical conductivity, porosity, swelling and degradation was investigated. Moreover, cytotoxicity and proliferation were examined by culturing OLN-93 neural and human dermal fibroblasts cells on the Nanochitosan/PPy-Alg scaffold. Due to the high conductivity, the film with ratio 2:10 (PPy-Alg) was recognized more suitable for fabrication of the final scaffold. Results from FT-IR and SEM, evaluation of porosity, swelling and degradation, as well as viability and proliferation of OLN-93 neural and fibroblast cells confirmed cytocompatiblity of the Nanochitosan/PPy-Alg scaffold. Based on the features of the constructed scaffold, Nanochitosan/PPy-Alg scaffold can be a proper candidate for neural tissue engineering.

Fabrication and Biological Activity of 3D-Printed Polycaprolactone/Magnesium Porous Scaffolds for Critical Size Bone Defect Repair

Polycaprolactone (PCL) is widely used in bone tissue engineering due to its biocompatibility and mechanical strength. However, PCL is not biologically active and shows poor hydrophilicity, making it difficult for new bones to bind tightly to its surface. Magnesium (Mg), an important component of natural bone, exhibits good osteo-inductivity and biological activity. Therefore, porous PCL/Mg scaffolds, including pure PCL, PCL/5%Mg, PCL/10%Mg, and PCL/15%Mg, were prepared to elucidate whether the porous structure of scaffolds and the bioactivity of PCL may be enhanced via 3D printing and incorporation of Mg powder. Compared with the control group (pure PCL only), the hydrophilicity of composite PCL/Mg scaffolds was greatly increased, resulting in the scaffolds having decreased water contact angles. Tests for adhesion and proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) indicated that the PCL/10%Mg scaffold showed superior compatibility. Furthermore, as indicated by alkaline phosphatase (ALP) activity and semiquantitative analysis of alizarin red staining, PCL/10%Mg scaffolds exhibited significantly stronger osteogenic activity than the other scaffolds. Animal experiments demonstrated that PCL/10%Mg scaffolds displayed pro-osteogenic effects at an early stage (4 weeks) and produced more new bone mass 8-12 weeks following implantation, compared with the control group. Visceral and blood parameter analyses indicated that PCL/10%Mg scaffolds did not exert any noticeable toxic effects. PCL/10%Mg composite scaffolds were found to promote bone defect repair at an early stage with good cytocompatibility. This finding revealed a new concept in designing bone tissue materials, which showed potential as a clinical treatment for bone defects.

Physical, mechanical and in vitro evaluation of a novel cement based on akermantite and dicalcium phosphate dihydrate phase

Magnesium containing calcium silicates have recently shown that they are promising materials for various biomedical application with potential use in the form of bulk ceramic, composite scaffold or coatings on metallic substrates. A novel akermanite (AK; Ca₂MgSi₂O₇)/dicalcium phosphate dihydrate (DCPD, CaHPO₄. H₂O) cement mixture was tested in this work in order to produce an alternative AK/DCPD biocement for orthopedic applications. For comparison, we have prepared two cements mixed with 2.5 wt% NaH₂PO₄ solution (labeled as NaH₂PO₄ cement) and with the solution composed of organic 2.5 wt% citric acid a 2.5 wt% trisodium citrate (citrate cement) respectively. The results demonstrated only a partial dissolution of AK, regardless of the type of liquid used. On the other hand, the DCPD was completely hydrolyzed much faster in the citrate cement. The final hydration product was an amorhous quarternary phase of CaO-MgO-SiO₂-P₂O₅ composition with the remaining unreacted akermanite embeded in the cement matrix. The highest early compressive strength was observed in the citrate cement (33 MPa), but much lower value was measured in NaH₂PO₄ cement (7 MPa) after 1 d setting. Different cell responses have been observed when the cells were cultured on the surfaces of cement substrates. While the NaH₂PO₄ cement demonstrated high proliferation activity of osteoblast, the citrate cement showed strong cytotoxic cell response, probably as a result of higher concentration of citrates on the cement surface, which can negatively affect the attachment and proliferation of osteoblastic cells.

Adhesion and Proliferation of Osteoblast-Like Cells on Porous Polyetherimide Scaffolds

The purpose of this work was to investigate the porous polyetherimide scaffold (P-PEIs) as an alternative biopolymer for bone tissue engineering. The P-PEIs was fabricated via solvent casting and particulate leaching technique. The morphology, phase composition, roughness, hydrophilicity, and biocompatibility of P-PEIs were evaluated and compared with polyetherimide (PEI) and Ti6Al4V disks. P-PEIs showed a biomimetic porous structure with a modulus of 78.95 ± 2.30 MPa. The water contact angle of P-PEIs was 75.4 ± 3.39°, which suggested that P-PEIs had a wettability surface. Moreover, P-PEIs provides a feasible environment for cell adhesion and proliferation. The relative cell adhesion capability and the cell morphology on P-PEIs were better than PEI and Ti6Al4V samples. Furthermore, the MC3T3-E1 cells on P-PEIs showed faster proliferation rate than other groups. It was revealed that the P-PEIs could be a potential material for the application of bone regeneration.