Scaffolds For Bone Tissue Engineering Research Articles

Evaluation of human amnion denuded derived mesenchymal stem cell on 3D porous hydroxyapatite composite scaffolds for osteogenic differentiation: Prolonged in vitro study

Recent studies using composite porous scaffolds have globally demonstrated the biocompatibility of mesenchymal stem cell sources. It is especially important in hard tissue bioengineering due to its desirable features and stemness effectivity. This study has emphasized primarily the evaluation of the morphological aspects of human amnion-denuded derived mesenchymal stem cells (hAMMSC) in combination with the fabrication of three-dimensional (3D) porous hydroxyapatite (Hap) composite scaffolds for bone tissue engineering based on the principal component of bone mineralization. We presented a novel combination of hAMMSC and nano-crystalline powder hydroxyapatite/bioactive glass (Hap/BG) composite scaffolds fabricated through the hydrothermal method via a novel formulation method from a previous study of stem cell in vitro prolonged culture. The 3D porous scaffold, 6 mm in size, was fabricated from 70 nm nanocrystalline powder and interacted with hAMMSC cultured in osteo-inductive conditions for 30 days. The characterization of 3D porous scaffolds was analyzed via Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) to explore the particle structure, morphology, bioactivity, and porosity of the composite powder and scaffolds in contact with hAMMSCs culture. Furthermore, biocompatibility was assessed using the PrestoBlueTM viability assay and scanning electron microscopy observation (SEM), which revealed the attachment, morphology, and spreading of hAMMSCs on the 3D porous scaffolds of Hap/BG by showing spindle-like morphology and forming the spreading filopodia bridge-like structure within the scaffolds. Subsequently, the secondary objective is the characterization of human AMMSC differentiation capacity assessed by early osteoblast differentiation and mineralization behaviour investigated by early detected assay via alkaline phosphatase activity (ALP) activity marker and energy dispersive X-ray (EDX) analysis simultaneously of the mineralization within bone matrix elements. It was comparatively evaluated via ALP and EDX for calcium quantification elements. Immunomodulatory properties were analyzed via ELISA kits. In conclusion, our findings indicate that 3D porous scaffolds made of Hap/BG composites could be great candidates for future regenerative medicine applications due to their support towards stem cell growth and enhancement of bone cell capacity.

Effect of Porosity and Pore Shape on the Mechanical and Biological Properties of Additively Manufactured Bone Scaffolds.

This study investigates the effect of porosity and pore shape on the biological and mechanical behavior of additively manufactured scaffolds for bone tissue engineering (BTE). Polylactic acid scaffolds with varying porosity levels (15-78%) and pore shapes, including regular (rectangular pores), gyroid, and diamond (triply periodic minimal surfaces) structures, are fabricated by fused filament fabrication. Murine-derived macrophages and human bone marrow-derived mesenchymal stromal cells (hBMSCs) are seeded onto the scaffolds. The compressive behavior and surface morphology of the scaffolds are characterized. The results show that scaffolds with 15%, 30%, and 45% porosity display the highest rate of macrophage and hBMSC growth. Gyroid and diamond scaffolds exhibit a higher rate of macrophage proliferation, while diamond scaffolds exhibit a higher rate of hBMSC proliferation. Additionally, gyroid and diamond scaffolds exhibit better compressive behavior compared to regular scaffolds. Of particular note, diamond scaffolds have the highest compressive modulus and strength. Surface morphology characterization indicates that the surface roughness of diamond and gyroid scaffolds is greater than that of regular scaffolds at the same porosity level, which is beneficial for cell attachment and proliferation. This study provides valuable insights into porosity and pore shape selection for additively manufactured scaffolds in BTE.

Ti6Al4V biomimetic scaffolds for bone tissue engineering: Fabrication, biomechanics and osseointegration

The design of porous structure that mimic trabecular bone is an effective method for optimizing the elastic modulus and osseointegration properties of titanium alloy implants. However, there is no consensus on which structure is best. In this study, we fabricated 24 different types of Ti6Al4V trabecular bone scaffolds with varying porosity and average pore size using Voronoi algorithm and selective laser melting technology. The biomechanics and osseointegration properties were studied by mechanical tests, computational fluid dynamics, cell and animal experiments. Our results showed that with an increase of porosity and average pore size, the scaffold's yield strength, ultimate strength, elastic modulus and shear stress exhibited an overall decreasing trend while the permeability and nutrient transport improved. Cell experiments showed that reducing the average pore size enhanced the adhesion and proliferation of MC3T3-E1 cells when the porosity was constant. Animal experiments showed that the scaffold with 65% porosity and 550 μm pore size had the most significant new bone formation effect. Based on our research results, we concluded that a porous structure design with 65% porosity and an average pore size of 550 μm, resembling bone trabecular, had the most significant effect on enhancing the comprehensive performance of titanium alloy implants.

Proliferation and differential regulation of osteoblasts cultured on surface-phosphorylated cellulose nanofiber scaffolds

Phosphorus-containing polymers have received much attention for their excellent ability to regulate bone cell differentiation and calcification. Given the increasing concern about environmental issues, it is promising to utilize “green” biomaterials to construct novel cell culture scaffolds for bone tissue engineering. Herein, surface-phosphorylated cellulose nanofibers (P-CNFs) were fabricated as a novel green candidate for osteoblast culture. Compared with native CNF, P-CNFs possessed shorter fiber morphology with tunable phosphate group content (0–1.42 mmol/g). The zeta-potential values of CNFs were enhanced after phosphorylation, resulting in the formation of uniform and stable scaffolds. The cell culture behavior of mouse osteoblast (MC3T3-E1) cells showed a clear phosphate content-dependent cell proliferation. The osteoblast cells adhered well and proliferated efficiently on P-CNF0.78 and P-CNF1.05, with phosphate contents of 0.78 and 1.05 mmol/g, respectively, whereas the cells grown on native CNF substrate formed aggregates due to poor cell attachment and exhibited limited cell proliferation. In addition, the P-CNF substrates with optimal phosphate content provided a favorable cellular microenvironment and significantly promoted osteogenic differentiation and calcification, even in the absence of a differentiation inducer. The bio-based P-CNFs are expected to mimic the bone components and provide a means to regulate osteoblast proliferation and differentiation in bone tissue engineering.

Physicochemical and in vitro investigation of trace element-incorporated hydroxyapatite and starPCL@chitosan composite scaffold for bone tissue engineering

Organic-inorganic composite scaffolds are of interest for bone tissue engineering and post injury-bone regeneration. In the present study, aimed to investigate the suitability of the trace element-incorporated hydroxyapatite (THA) integrated bioactive gel (BioGel) (star-shaped polycaprolactone (starPCL)/Chitosan (Chit)) (THAiBioGel) composite scaffold which was fabricated using melt/solution blending method as a bone scaffold. The results revealed that the as-prepared THAiBioGel demonstrated that THA was successfully incorporated into BioGel and yield a desirable porous structure with mechanical strength of 10.35 ± 0.27 MPa, 13.62 ± 0.32 MPa and 18.30 ± 0.54 MPa for weight ratio of THA:BioGel 5:5, 7:3 and 9:1, respectively. Furthermore, the in vitro biological assay confirmed that the present material was not only good for osteoblast-like UMR-106 cell attachment on its surface, but also significantly promoted bone formation as demonstrated by an increase in alkaline phosphatase (ALP) activity. Our data, therefore, strongly suggested that THAiBioGel could be used as scaffold for bone tissue engineering.

The symbiotic effect of osteoinductive extracellular vesicles and mineralized microenvironment on osteogenesis.

The increasing prevalence of bone-related diseases has raised concern about the need for an osteoinductive and mechanically stronger scaffold-based bone tissue engineering (BTE) alternative. A mineralized microenvironment, similar to the native bone microenvironment, is required in the scaffold to recruit and differentiate local mesenchymal stem cells at the bone defect site. Further, extracellular vesicles (EVs), pre-osteoblasts' secretome, contain osteoinductive cargo and have recently been exploited in bone regeneration. This work developed a cell-free and mechanically strong interpenetrating network-based scaffold for BTE by combining the action of osteoinductive EVs with a mineralized microenvironment. The MC3T3 (a pre-osteoblast cell line) is used as a source of EVs and as the target population. The optimal concentration of MC3T3-EVs was first determined to induce osteogenesis in target cells. The osteoinductive potential of the scaffold was estimated in vitro by osteogenesis-related markers like the alkaline phosphatase (ALP) enzyme and calcium content. The MC3T3-EVs cargo was also studied for osteoinductive signals such as ALP, calcium, and mRNA. The findings of this work indicated that MC3T3-EVs at a 90 μg/mL dose had significantly higher ALP activity than 0 μg/mL (1.47-fold), 10 μg/mL (1.41-fold), and 30 μg/mL (1.39-fold) EV-concentration on day 14. Further combination of the optimum dose of EVs with a mineralized microenvironment significantly enhanced ALP activity (1.5-fold) and mineralization (3.36-fold) as compared to the control group on day 7. EV cargo analysis revealed the presence of calcium, the ALP enzyme, and the mRNAs necessary for osteogenesis and angiogenesis. ALP activity was significantly boosted in the EV-containing target cells as early as day 1, and mineralization began on day 7 because MC3T3-EVs carry ALP enzymes and calcium as cargo. When osteoinductive EVs were combined with an osteoconductive mineralized microenvironment, osteogenesis was significantly enhanced in target cells at early time points. The interaction between osteoinductive EVs and the mineralized milieu facilitates the process of osteogenesis in the target cells and suggests a potential cell-free strategy for in vivo bone repair.

Use of 3D-printed polylactic acid/bioceramic composite scaffolds for bone tissue engineering in preclinical in vivo studies: A systematic review.

3D-printed composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. The aim of the study was to systematically review the feasibility of using PLA/bioceramic composite scaffolds manufactured by 3D-printing technologies as bone grafting materials in preclinical in vivo studies. Electronic databases were searched using specific search terms, and thirteen manuscripts were selected after screening. The synthesis of the scaffolds was carried out using mainly extrusion-based techniques. Likewise, hydroxyapatite was the most used bioceramic for synthesizing composites with a PLA matrix. Among the selected studies, seven were conducted in rats and six in rabbits, but the high variability that exists regarding the experimental process made it difficult to compare them. Regarding the results, PLA/Bioceramic composite scaffolds have shown to be biocompatible and mechanically resistant. Preclinical studies elucidated the ability of the scaffolds to be used as bone grafts, allowing bone growing without adverse reactions. In conclusion, PLA/Bioceramics scaffolds have been demonstrated to be a promising alternative for treating bone defects. Nevertheless, more care should be taken when designing and performing in vivo trials, since the lack of standardization of the processes, which prevents the comparison of the results and reduces the quality of the information. STATEMENT OF SIGNIFICANCE: 3D-printed polylactic acid/bioceramic composite scaffolds have emerged as an alternative to deal with existing limitations when facing bone reconstruction. Since preclinical in vivo studies with animal models represent a mandatory step for clinical translation, the present manuscript analyzed and discussed not only those aspects related to the selection of the bioceramic material, the synthesis of the implants and their characterization. But provides a new approach to understand how the design and perform of clinical trials, as well as the selection of the analysis methods, may affect the obtained results, by covering authors' knowledgebase from veterinary medicine to biomaterial science. Thus, this study aims to systematically review the feasibility of using polylactic acid/bioceramic scaffolds as grafting materials in preclinical trials.

Development of a Novel Marine-Derived Tricomposite Biomaterial for Bone Regeneration.

Bone tissue engineering is a promising treatment for bone loss that requires a combination of porous scaffold and osteogenic cells. The aim of this study was to evaluate and develop a tricomposite, biomimetic scaffold consisting of marine-derived biomaterials, namely, chitosan and fucoidan with hydroxyapatite (HA). The effects of chitosan, fucoidan and HA individually and in combination on the proliferation and differentiation of human mesenchymal stem cells (MSCs) were investigated. According to the SEM results, the tricomposite scaffold had a uniform porous structure, which is a key requirement for cell migration, proliferation and vascularisation. The presence of HA and fucoidan in the chitosan tricomposite scaffold was confirmed using FTIR, which showed a slight decrease in porosity and an increase in the density of the tricomposite scaffold compared to other formulations. Fucoidan was found to inhibit cell proliferation at higher concentrations and at earlier time points when applied as a single treatment, but this effect was lost at later time points. Similar results were observed with HA alone. However, both HA and fucoidan increased MSC mineralisation as measured by calcium deposition. Differentiation was significantly enhanced in MSCs cultured on the tricomposite, with increased alkaline phosphatase activity on days 17 and 25. In conclusion, the tricomposite is biocompatible, promotes osteogenesis, and has the structural and compositional properties required of a scaffold for bone tissue engineering. This biomaterial could provide an effective treatment for small bone defects as an alternative to autografts or be the basis for cell attachment and differentiation in ex vivo bone tissue engineering.

Novel Electroactive Mineralized Polyacrylonitrile/PEDOT:PSS Electrospun Nanofibers for Bone Repair Applications.

Bone defect repair remains a critical challenge in current orthopedic clinical practice, as the available therapeutic strategies only offer suboptimal outcomes. Therefore, bone tissue engineering (BTE) approaches, involving the development of biomimetic implantable scaffolds combined with osteoprogenitor cells and native-like physical stimuli, are gaining widespread interest. Electrical stimulation (ES)-based therapies have been found to actively promote bone growth and osteogenesis in both in vivo and in vitro settings. Thus, the combination of electroactive scaffolds comprising conductive biomaterials and ES holds significant promise in improving the effectiveness of BTE for clinical applications. The aim of this study was to develop electroconductive polyacrylonitrile/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PAN/PEDOT:PSS) nanofibers via electrospinning, which are capable of emulating the native tissue's fibrous extracellular matrix (ECM) and providing a platform for the delivery of exogenous ES. The resulting nanofibers were successfully functionalized with apatite-like structures to mimic the inorganic phase of the bone ECM. The conductive electrospun scaffolds presented nanoscale fiber diameters akin to those of collagen fibrils and displayed bone-like conductivity. PEDOT:PSS incorporation was shown to significantly promote scaffold mineralization in vitro. The mineralized electroconductive nanofibers demonstrated improved biological performance as observed by the significantly enhanced proliferation of both human osteoblast-like MG-63 cells and human bone marrow-derived mesenchymal stem/stromal cells (hBM-MSCs). Moreover, mineralized PAN/PEDOT:PSS nanofibers up-regulated bone marker genes expression levels of hBM-MSCs undergoing osteogenic differentiation, highlighting their potential as electroactive biomimetic BTE scaffolds for innovative bone defect repair strategies.

Modified-Hydroxyapatite-Chitosan Hybrid Composite Interfacial Coating on 3D Polymeric Scaffolds for Bone Tissue Engineering.

Three dimensional (3D) scaffolds have huge limitations due to their low porosity, mechanical strength, and lack of direct cell-bioactive drug contact. Whereas bisphosphonate drug has the ability to stimulate osteogenesis in osteoblasts and bone marrow mesenchymal stem cells (hMSC) which attracted its therapeutic use. However it is hard administration low bioavailability, and lack of site-specificity, limiting its usage. The proposed scaffold architecture allows cells to access the bioactive surface at their apex by interacting at the scaffold's interfacial layer. The interface of 3D polycaprolactone (PCL) scaffolds has been coated with alendronate-modified hydroxyapatite (MALD) enclosed in a chitosan matrix, to mimic the native environment and stupulate the through interaction of cells to bioactive layer. Where the mechanical strength will be provided by the skeleton of PCL. In the MALD composite's hydroxyapatite (HAP) component will govern alendronate (ALD) release behavior, and HAP presence will drive the increase in local calcium ion concentration increases hMSC proliferation and differentiation. In results, MALD show release of 86.28±0.22. XPS and SEM investigation of the scaffold structure, shows inspiring particle deposition with chitosan over the interface. All scaffolds enhanced cell adhesion, proliferation, and osteocyte differentiation for over a week without in vitro cell toxicity with 3.03±0.2kPa mechanical strength.

Hydroxyapatite-filled osteoinductive and piezoelectric nanofibers for bone tissue engineering

ABSTRACT Osteoporotic-related fractures are among the leading causes of chronic disease morbidity in Europe and in the US. While a significant percentage of fractures can be repaired naturally, in delayed-union and non-union fractures surgical intervention is necessary for proper bone regeneration. Given the current lack of optimized clinical techniques to adequately address this issue, bone tissue engineering (BTE) strategies focusing on the development of scaffolds for temporarily replacing damaged bone and supporting its regeneration process have been gaining interest. The piezoelectric properties of bone, which have an important role in tissue homeostasis and regeneration, have been frequently neglected in the design of BTE scaffolds. Therefore, in this study, we developed novel hydroxyapatite (HAp)-filled osteoinductive and piezoelectric poly(vinylidene fluoride-co-tetrafluoroethylene) (PVDF-TrFE) nanofibers via electrospinning capable of replicating the tissue’s fibrous extracellular matrix (ECM) composition and native piezoelectric properties. The developed PVDF-TrFE/HAp nanofibers had biomimetic collagen fibril-like diameters, as well as enhanced piezoelectric and surface properties, which translated into a better capacity to assist the mineralization process and cell proliferation. The biological cues provided by the HAp nanoparticles enhanced the osteogenic differentiation of seeded human mesenchymal stem/stromal cells (MSCs) as observed by the increased ALP activity, cell-secreted calcium deposition and osteogenic gene expression levels observed for the HAp-containing fibers. Overall, our findings describe the potential of combining PVDF-TrFE and HAp for developing electroactive and osteoinductive nanofibers capable of supporting bone tissue regeneration.

Alginate hydrogels containing different concentrations of magnesium-containing poly(lactic-co-glycolic acid) microspheres for bone tissue engineering

The easy loss of crosslinking ions in alginate can result in structural collapse and loss of its characteristics as a bone scaffold. A novel injectable tissue engineering scaffold containing poly(lactic-co-glycolic acid) (PLGA) microspheres and alginate was fabricated to improve alginate’s physiochemical and biological properties. MgCO3 and MgO were loaded at a 1:1 ratio into PLGA microspheres to form biodegradable PLGA microspheres containing magnesium (PMg). Subsequently, different concentrations of PMg were mixed into a Ca2+ suspension and employed as crosslinking agents for an alginate hydrogel. A pure Ca2+ suspension was used as the alginate crosslinking agent in the control group. The influence of PMg on the physiochemical properties of the injectable scaffolds, including the surface morphology, degradation rate, Mg2+ precipitation concentration, and the swelling rate, was investigated. MC3T3-E1 cells were seeded onto the hydrogels to evaluate the effect of the resultant alginate on osteoblastic attachment, proliferation, and differentiation. The physicochemical properties of the hydrogels, including morphology, degradation rate, and swelling ratio, were effectively tuned by PMg. Inductively coupled plasma-optical emission spectroscopy results showed that, in contrast to those in pure PMg, the magnesium ions (Mg2+) in alginate hydrogel containing PMg microspheres (Alg-PMg) were released in a dose-dependent and slow-releasing manner. Additionally, Alg-PMg with an appropriate concentration of PMg not only improved cell attachment and proliferation but also upregulated alkaline phosphatase activity, gene expression of osteogenic markers, and related growth factors. These findings indicate that PMg incorporation can regulate the physicochemical properties of alginate hydrogels. The resultant hydrogel promoted cell attachment, matrix mineralization, and bone regeneration. The hydrogel described in this study can be considered a promising injectable scaffold for bone tissue engineering.

Hydroxyapatite/Polyurethane Scaffolds for Bone Tissue Engineering.

Polyurethane (PU) and PU ceramic scaffolds are the principal materials investigated for developing synthetic bone materials due to their excellent biocompatibility and biodegradability. PU has been combined with calcium phosphate (such as hydroxyapatite [HA] and tricalcium phosphate) to prepare scaffolds with enhanced mechanical properties and biocompatibility. This article reviews the latest progress in the design, synthesis, modification, and biological attributes of HA/PU scaffolds for bone tissue engineering. Diverse HA/PU scaffolds have been proposed and discussed in terms of their osteogenic, antimicrobial, biocompatibility, and bioactivities. The application progress of HA/PU scaffolds in bone tissue engineering is predominantly introduced, including bone repair, bone defect filling, drug delivery, and long-term implants.

Angiogenesis-promoting composite TPMS bone tissue engineering scaffold for mandibular defect regeneration

Mandibular defects severely impact the patient’s quality of life and are difficult problems to treat in the clinical setting. Due to the limitations of current gold-standard therapies, there is a tremendous need for tissue engineering approaches to meet this rising clinical demand. Injectable platelet-rich fibrin (I-PRF) containing a variety of pro-regenerative growth factors and stromal cell-derived factor-1 (SDF-1) has been shown to be beneficial in stimulating angiogenesis. In this study, we developed a three-cycle minimally curved biomimetic bone tissue engineering scaffold made of β-tricalcium phosphate, modified with I-PRF and SDF-1. I-PRF was loaded at a concentration of 5% onto a triply periodic minimal surface (TPMS) scaffold with a porosity of 70%. CCK-8 experiments and live-dead staining confirmed the scaffold’s good biocompatibility and its ability to promote cell proliferation. Wound healing assays showed that the TPMS scaffold loaded with I-PRF and SDF-1 (SIT) enhanced cell migration of MC3T3 cells. Moreover, angiogenesis experiments showed that the SIT scaffold promoted angiogenesis. Importantly, alkaline phosphatase and alizarin red staining confirmed that the bone scaffold accelerated MC3T3 cells’ osteogenic differentiation and mineralization. The SIT bone scaffold was then implanted into a rabbit mandible defect model. After a 2-month post-implantation period, micro- CT analysis revealed the growth of new bone tissue around the SIT construct, while histological analysis which included hematoxylin-eosin (H&E) staining and masson’s trichrome staining, alkaline phosphatase (ALP) staining, osteoprotegerin (OPG) staining demonstrated that the SIT scaffold substantially promoted the growth of a highly vascularized fibrous and bone tissue in the defect site. Taken together, these findings demonstrate the considerable potential of TPMS scaffolds loaded with I-PRF and SDF-1 in promoting the repair of mandible defects.

In vitro investigation of poly(propylene fumarate) cured with phosphonic acid based monomers as scaffolds for bone tissue engineering

In vitro investigation of poly(propylene fumarate) cured with phosphonic acid based monomers as scaffolds for bone tissue engineering

Fabrication and characterization of 3D printing biocompatible crocin-loaded chitosan/collagen/hydroxyapatite-based scaffolds for bone tissue engineering applications

IntroductionCrocin (Cro) is a bioactive biomaterial with properties that promote osteoconduction, osteoinduction, and osteogenic differentiation, making it an ideal candidate for developing mechanically enhanced scaffolds for bone tissue engineering (BTE). Present study focused on a 3D printing matrix loaded with Cro and featuring a composite structure consisting of Chitosan (CH), collagen (Col), and hydroxyapatite (HA). MethodThe scaffolds' structural properties were analyzed using FESEM, and FTIR DSC, while the degradation rate, swelling ratio, cell viability were examined to determine their in vitro performance. Additionally, the scaffolds' mechanical properties were calculated by examining their force, stress, elongation, and Young's modulus. ResultsThe CH/Col/nHA scaffolds demonstrated interconnected porous structures. The cell study results indicated that the Cro-loaded in scaffolds cause to reduce the toxicity of Cro. Biocompatibility was confirmed through degradation rate, swelling ratio parameters, and contact angle measurements for all structures. The addition of Cro showed a significant impact on the strength of the fabricated scaffolds. By loading 25 and 50 μl of Cro, the Young's modulus improved by 71 % and 74 %, respectively, compared to the free drug scaffold. ConclusionThe obtained results indicated that the 3D printing crocin-loaded scaffolds based chitosan/collagen/hydroxyapatite structure can be introduced as a promising candidate for BTE applications.

The effect of temperature on the physical-chemical properties of bovine hydroxyapatite biomimetic scaffolds for bone tissue engineering

This work focuses on the changes in hydroxyapatite (HAp) scaffolds obtained from bovine trabecular bone after heat treatments ranging from 400 to 1100 °C. The main objective is to gain a comprehensive understanding of the thermal behavior and structural modifications of these HAp scaffolds and evaluate their suitability for specific applications.Thermal analysis using thermogravimetry and differential scanning calorimetry revealed distinct thermal events associated with HAp crystallite coalescence, carbonate elimination, and Mg out-diffusion. Fourier transform infrared spectroscopy demonstrates the presence of organics in samples annealed at temperatures below 500 °C and the elimination of carbonates in samples annealed at temperatures above 700 °C.Raman spectroscopy indicated a transition from nano-to-micro-sized HAp crystallites in both the raw and samples annealed at 400 and 500 °C. X-ray diffraction analysis shows changes in the full width at half maximum (FWHM) of the (002) peak for the annealed samples. Crystalline parameters were determined using Rietveld refinement. Scanning electron microscopy images revealed the phenomenon of HAp crystallite coalescence during heat treatment. The growth of the crystallites and the transition from nano to micro size occurred at approximately 600 °C.Importantly, the macroporosity of the HAp scaffolds remained unchanged regardless of the calcination temperature, while mesoporosity was observed only in scaffolds calcined at lower temperatures (400, 500, and 600 °C). Furthermore, the raw, 400, and 500 °C scaffolds retained organic materials, resulting in improved mechanical properties.These findings provide valuable insights into the thermal behavior and structural changes of HAp scaffolds derived from bovine trabecular bone. The study suggests that scaffolds calcined at 600 °C exhibit suitable properties for bone tissue engineering applications, predominantly consisting of carbonated HAp nanocrystals, featuring three types of porosity, and are free of organic material.

Low-temperature deposition manufacturing technology: a novel 3D printing method for bone scaffolds.

The application of three-dimensional printing technology in the medical field has great potential for bone defect repair, especially personalized and biological repair. As a green manufacturing process that does not involve liquefication through heating, low-temperature deposition manufacturing (LDM) is a promising type of rapid prototyping manufacturing and has been widely used to fabricate scaffolds in bone tissue engineering. The scaffolds fabricated by LDM have a multi-scale controllable pore structure and interconnected micropores, which are beneficial for the repair of bone defects. At the same time, different types of cells or bioactive factor can be integrated into three-dimensional structural scaffolds through LDM. Herein, we introduced LDM technology and summarize its applications in bone tissue engineering. We divide the scaffolds into four categories according to the skeleton materials and discuss the performance and limitations of the scaffolds. The ideas presented in this review have prospects in the development and application of LDM scaffolds.

Preparation and characterization of novel poly (lactic acid)/calcium oxide nanocomposites by electrospinning as a potential bone tissue scaffold

Calcium oxide nanoparticles (n-CaO) ca. 22 nm were obtained from eggshell waste. The n-CaO was incorporated into the PLA matrix in 10 and 20 wt% of filler content by electrospinning process to get PLA/n-CaO fibers with homogenous morphology and diameter as a potential use in scaffold for bone tissue regeneration. The incorporation of n-CaO into PLA modifies the mechanical properties, having a reinforcement effect on the matrix. The Young modulus for PLA/n-CaO nanocomposites increased between 122 and 138 % concerning neat PLA fibers, showing a more rigid behavior. The PLA/n-CaO nanocomposite fibers showed in vitro bioactivity, capable of inducing the precipitation of hydroxyapatite (HA) layer in the fiber surface after seven days in SBF solution. The biocidal and biological properties of PLA/n-Cao with 20 wt% showed a 30 % reduction in bacterial viability against S. aureus and 11 % against E. coli after 6 h of bacterial exposure. Furthermore, the fibers did not show a cytotoxic effect on the bone marrow ST-2 cell line, allowing cell adhesion and proliferation in the RPMI medium. The PLA/n-CaO with 20 wt% of nanoparticles showed a higher capacity to promote osteogenic differentiation, significantly increasing the alkaline phosphatase (ALP) expression after seven days compared to PLA and cell control. The in vivo analysis corroborated the biocompatibility of the prepared scaffolds; the presence of n-CaO in PLA reduced the formation of fibrous encapsulation of the material, improving the healing process. These results validated using n-CaO to enhance the functionality of polymer matrices as a PLA, bringing bioactive, biocide, and biocompatible properties, opening a new and interesting route to develop new biomaterials as a scaffold for bone tissue engineering.

Cytocompatible and osteoinductive cotton cellulose nanofiber/chitosan nanobiocomposite scaffold for bone tissue engineering

Natural polymeric nanobiocomposites hold promise in repairing damaged bone tissue in tissue engineering. These materials create an extracellular matrix (ECM)-like microenvironment that induces stem cell differentiation. In this study, we investigated a new cytocompatible nanobiocomposite made from cotton cellulose nanofibers (CNFs) combined with chitosan polymer to induce osteogenic stem cell differentiation. First, we characterized the chemical composition, nanotopography, swelling properties, and mechanical properties of the cotton CNF/chitosan nanobiocomposite scaffold. Then, we examined the biological characteristics of the nanocomposites to evaluate their cytocompatibility and osteogenic differentiation potential using human mesenchymal stem cells derived from exfoliated deciduous teeth. The results showed that the nanobiocomposite exhibited favorable cytocompatibility and promoted osteogenic differentiation of cells without the need for chemical inducers, as demonstrated by the increase in alkaline phosphatase activity and ECM mineralization. Therefore, the cotton CNF/chitosan nanobiocomposite scaffold holds great promise for bone tissue engineering applications.