Scaffolds For Bone Tissue Engineering Research Articles

Current Perspectives of Protein in Bone Tissue Engineering: Bone Structure, Ideal Scaffolds, Fabrication Techniques, Applications, Scopes, and Future Advances.

In view of their exceptional approach, excellent inherent biocompatibility and biodegradability properties, and interaction with the local extracellular matrix, protein-based polymers have received attention in bone tissue engineering, which is a multidisciplinary field that repairs and regenerates fractured bones. Bone is a multihierarchical complex structure, and it performs several essential biofunctions, including maintaining mineral balance and structural support and protecting soft organs. Protein-based polymers have gained interest in developing ideal scaffolds as emerging biomaterials for bone fractured healing and regeneration, and it is challenging to design ideal bone substitutes as perfect biomaterials. Several protein-based polymers, including collagen, keratin, gelatin, serum albumin, etc., are potential materials due to their inherent cytocompatibility, controlled biodegradability, high biofunctionalization, and tunable mechanical characteristics. While numerous studies have indicated the encouraging possibilities of proteins in BTE, there are still major challenges concerning their biodegradability, stability in physiological conditions, and continuous release of growth factors and bioactive molecules. Robust scaffolds derived from proteins can be used to replace broken or diseased bone with a biocompatible substitute; proteins, being biopolymers, provide excellent scaffolds for bone tissue engineering. Herein, recent developments in protein polymers for cutting-edge bone tissue engineering are addressed in this review within 3-5 years, with a focus on the significant challenges and future perspectives. The first section discusses the structural fundamentals of bone anatomy and ideal scaffolds, and the second section describes the fabrication techniques of scaffolds. The third section highlights the importance of proteins and their applications in BTE. Hence, the recent development of protein polymers for state-of-the-art bone tissue engineering has been discussed, highlighting the significant challenges and future perspectives.

Effect of nanodiamonds surface deposition on hydrophilicity, bulk degradation and in-vitro cell adhesion of 3D-printed polycaprolactone scaffolds for bone tissue engineering

This study was designed to deposit nanodiamonds (NDs) on 3D-printed poly-ϵ-caprolactone (PCL) scaffolds and evaluate their effect on the surface topography, hydrophilicity, degradation, andin-vitrocell adhesion compared to untreated PCL scaffolds. The PCL scaffold specimens were 3D-printed by fused deposition modeling (FDM) technique with specific porosity parameters. The 3D-printed specimens' surfaces were modified by NDs deposition followed by oxygen plasma post-treatment using a plasma focus device and a non-thermal atmospheric plasma jet, respectively. Specimens were evaluated through morphological characterization by field emission scanning electron microscope (FESEM), microstructure characterization by Raman spectroscopy, chemical characterization by Fourier transform infrared (FTIR) spectroscopy, hydrophilicity degree by contact angle and water uptake measurements, andin-vitrodegradation measurements (n= 6). In addition,in-vitrobone marrow mesenchymal stem cells adhesion was evaluated quantitatively by confocal microscopy and qualitatively by FESEM at different time intervals after cell seeding (n= 6). The statistical significance level was set atp⩽ 0.05. The FESEM micrographs, the Raman, and FTIR spectra confirmed the successful surface deposition of NDs on scaffold specimens. The NDs treated specimens showed nano-scale features distributed homogeneously across the surface compared to the untreated ones. Also, the NDs treated specimens revealed a statistically significant smaller contact angle (17.45 ± 1.34 degrees), higher water uptake percentage after 24 h immersion in phosphate buffer saline (PBS) (21.56% ± 1.73), and higher degradation rate after six months of immersion in PBS (43.92 ± 0.77%). Moreover, enhanced cell adhesion at all different time intervals was observed in NDs treated specimens with higher nuclei area fraction percentage (69.87 ± 3.97%) compared to the untreated specimens (11.46 ± 1.34%). Surface deposition of NDs with oxygen-containing functional groups on 3D-printed PCL scaffolds increased their hydrophilicity and degradation rate with significant enhancement of thein-vitrocell adhesion compared to untreated PCL scaffolds.

Multi-parameter design of triply periodic minimal surface scaffolds: from geometry optimization to biomechanical simulation

This study introduces a multi-parameter design methodology to create triply periodic minimal surface (TPMS) scaffolds with predefined geometric characteristics. The level-set constant and unit cell lengths are systematically correlated with targeted porosity and minimum pore sizes. Network and sheet scaffolds featuring diamond, gyroid, and primitive level-set structures are generated. Three radially graded schemes are applied to each of the six scaffold type, accommodating radial variations in porosity and pore sizes. Computer simulations are conducted to assess the biomechanical performance of 18 scaffold models. Results disclose that diamond and gyroid scaffolds exhibit more expansive design ranges than primitive counterparts. While primitive scaffolds display the highest Young’s modulus and permeability, their lower yield strength and mesenchymal stem cell (MSC) adhesion render them unsuitable for bone scaffolds. Gyroid scaffolds demonstrate superior mechanical and permeability performances, albeit with slightly lower MSC adhesion than diamond scaffolds. Sheet scaffolds, characterized by more uniform material distribution, exhibit superior mechanical performance in various directions, despite slightly lower permeability. The higher specific surface area of sheet scaffolds contributes to elevated MSC adhesion. The stimulus factor analysis also revealed the superior differentiation potential of sheet scaffolds over network ones. The diamond sheet type demonstrated the optimal differentiation. Introducing radial gradations enhances axial mechanical performance at the expense of radial mechanical performance. Radially decreasing porosity displays the highest permeability, MSC adhesion, and differentiation capability, aligning with the structural characteristics of human bones. This study underscores the crucial need to balance diverse biomechanical properties of TPMS scaffolds for bone tissue engineering.

Centrifugally spun hydroxyapatite/carbon composite nanofiber scaffolds for bone tissue engineering

In recent years, advancements in tissue engineering have demonstrated the potential to expedite bone matrix formation, leading to shorter recovery times and decreased clinical challenges compared to conventional methods. Therefore, this study aims to develop composite carbon nanofibers (CNFs) integrated with nano-hydroxyapatite (nHA) particles as scaffolds for bone tissue engineering applications. A key strategy in achieving this objective involves harnessing nanofibrous structures, which offer a high surface area, coupled with nHA particles expected to accelerate bone regeneration and enhance biological activity. To realize this, polyacrylonitrile (PAN)/nHA nanofibers were fabricated using the centrifugal spinning (C-Spin) technique and subsequently carbonized to yield CNF/nHA composite structures. Scanning Electron Microscopy (SEM) confirmed C-Spin as a suitable method for PAN and CNF nanofiber production, with nHA particles uniformly dispersed throughout the nanofibrous structure. Carbonization resulted in reduced fiber diameter due to thermal decomposition and shrinkage of PAN molecules during the process. Furthermore, the incorporation of nHA particles into PAN lowered the stabilization temperature (by 5 °C–20 °C). Tensile tests revealed that PAN samples experienced an approximately 80% increase in ultimate tensile strength and a 187% increase in modulus with a 5 wt.% nHA loading. However, following carbonization, CNF samples exhibited a 50% decrease in strength compared to PAN samples. Additionally, the addition of nHA into CNF improved the graphitic structure. The incorporation of nHA particles into the spinning solution represents a viable strategy for enhancing CNF bioactivity.

Graded or random – Effect of pore distribution in 3D titanium scaffolds on corrosion performance and response of hMSCs

Researchers agree that the ideal scaffold for tissue engineering should possess a 3D and highly porous structure, biocompatibility to encourage cell/tissue growth, suitable surface chemistry for cell attachment and differentiation, and mechanical properties that match those of the surrounding tissues. However, there is no consensus on the optimal pore distribution. In this study, we investigated the effect of pore distribution on corrosion resistance and performance of human mesenchymal stem cells (hMSC) using titanium scaffolds fabricated by laser beam powder bed fusion (PBF-LB). We designed two scaffold architectures with the same porosities (i.e., 75 %) but different distribution of pores of three sizes (200, 500, and 700 μm). The pores were either grouped in three zones (graded, GRAD) or distributed randomly (random, RAND). Microfocus X-ray computed tomography revealed that the chemically polished scaffolds had the porosity of 69 ± 4 % (GRAD) and 71 ± 4 % (RAND), and that the GRAD architecture had the higher surface area (1580 ± 101 vs 991 ± 62 mm2) and the thinner struts (221 ± 37 vs 286 ± 14 μm). The electrochemical measurements demonstrated that the apparent corrosion rate of chemically polished GRAD scaffold decreased with the immersion time extension, while that for polished RAND was increased. The RAND architecture outperformed the GRAD one with respect to hMSC proliferation (over two times higher although the GRAD scaffolds had 85 % higher initial cell retention) and migration from a monolayer. Our findings demonstrate that the pore distribution affects the biological properties of the titanium scaffolds for bone tissue engineering.

Graded or random – Effect of pore distribution in 3D titanium scaffolds on corrosion performance and response of hMSCs

Researchers agree that the ideal scaffold for tissue engineering should possess a 3D and highly porous structure, biocompatibility to encourage cell/tissue growth, suitable surface chemistry for cell attachment and differentiation, and mechanical properties that match those of the surrounding tissues. However, there is no consensus on the optimal pore distribution. In this study, we investigated the effect of pore distribution on corrosion resistance and performance of human mesenchymal stem cells (hMSC) using titanium scaffolds fabricated by laser beam powder bed fusion (PBF-LB). We designed two scaffold architectures with the same porosities (i.e., 75 %) but different distribution of pores of three sizes (200, 500, and 700 μm). The pores were either grouped in three zones (graded, GRAD) or distributed randomly (random, RAND). Microfocus X-ray computed tomography revealed that the chemically polished scaffolds had the porosity of 69 ± 4 % (GRAD) and 71 ± 4 % (RAND), and that the GRAD architecture had the higher surface area (1580 ± 101 vs 991 ± 62 mm2) and the thinner struts (221 ± 37 vs 286 ± 14 μm). The electrochemical measurements demonstrated that the apparent corrosion rate of chemically polished GRAD scaffold decreased with the immersion time extension, while that for polished RAND was increased. The RAND architecture outperformed the GRAD one with respect to hMSC proliferation (over two times higher although the GRAD scaffolds had 85 % higher initial cell retention) and migration from a monolayer. Our findings demonstrate that the pore distribution affects the biological properties of the titanium scaffolds for bone tissue engineering.

Internal flow field analysis of a dendritic pore scaffold for bone tissue engineering

The effective reconstruction of osteochondral biomimetic structures is a key factor in guiding the regeneration of full-thickness osteochondral defects. Due to the avascular nature of hyaline cartilage, the greatest challenge in constructing this scaffold lies in both utilizing the biomimetic structure to promote vascular differentiation for nutrient delivery to hyaline cartilage, thereby enhancing the efficiency of osteochondral reconstruction, and effectively blocking vascular ingrowth into the cartilage layer to prevent cartilage mineralization. However, the intrinsic relationship between the planning of the microporous pipe network and the flow resistance in the biomimetic structure, and the mechanism of promoting cell adhesion to achieve vascular differentiation and inhibiting cell adhesion to block the growth of blood vessels are still unclear. Inspired by the structure of tree trunks, this study designed a biomimetic tree-like tubular network structure for osteochondral scaffolds based on Murray’s law. Utilizing computational fluid dynamics, the study investigated the influence of the branching angle of micro-pores on the flow velocity, pressure distribution, and scaffold permeability within the scaffold. The results indicate that when the differentiation angle exceeds 50 degrees, the highest flow velocity occurs at the confluence of tributaries at the ninth fractal position, forming a barrier layer. This structure effectively guides vascular growth, enhances nutrient transport capacity, increases flow velocity to promote cell adhesion, and inhibits cell infiltration into the cartilage layer.

Design of chemobrionic and biochemobrionic scaffolds for bone tissue engineering

Chemobrionic systems have attracted great attention in material science for development of novel biomimetic materials. This study aims to design a new bioactive material by integrating biosilica into chemobrionic structure, which will be called biochemobrionic, and to comparatively investigate the use of both chemobrionic and biochemobrionic materials as bone scaffolds. Biosilica, isolated from Amphora sp. diatom, was integrated into chemobrionic structure, and a comprehensive set of analysis was conducted to evaluate their morphological, chemical, mechanical, thermal, and biodegradation properties. Then, the effects of both scaffolds on cell biocompatibility and osteogenic differentiation capacity were assessed. Cells attached to the scaffolds, spread out, and covered the entire surface, indicating the absence of cytotoxicity. Biochemobrionic scaffold exhibited a higher level of mineralization and bone formation than the chemobrionic structure due to the osteogenic activity of biosilica. These results present a comprehensive and pioneering understanding of the potential of (bio)chemobrionics for bone regeneration.

3D printing of fish-scale derived hydroxyapatite/chitosan/PCL scaffold for bone tissue engineering

In the field of bone tissue repair, the treatment of bone defects has always posed a significant challenge. In recent years, the advancement of bone tissue engineering and regenerative medicine has sparked great interest in the development of innovative bone grafting materials. In this study, a novel hydroxyapatite (HA) material was successfully prepared and comprehensively characterized. Antimicrobial experiments and biological evaluations were conducted to determine its efficacy. Based on the aforementioned research findings, 3D printing technology was employed to fabricate HA/chitosan (CS)/ polycaprolactone (PCL) scaffolds. The composition of the scaffold materials was confirmed through X-ray diffractometer (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) tests, while the influence of different HA ratios on the scaffold surface morphology was observed. Additionally, antimicrobial experiments demonstrated the favorable antimicrobial activity of the scaffolds containing 30%HA + 5%CS + PCL. Furthermore, the water contact angle measurements confirmed the superhydrophilicity of the scaffolds. Finally, the excellent bioactivity and ability to promote tissue regeneration of the scaffolds were further confirmed by in vitro and in vivo experiments. This study provides new options for future repair and regeneration of bone tissue and clinical applications.

Customized 3D printed porous titanium scaffolds with nanotubes loading antibacterial drugs for bone tissue engineering

Abstract Due to the uncertainty of trauma or infection, customized bone substitutes are often required in clinic. Meanwhile, excessive use of antibiotics may lead to drug resistance. Therefore, the design of anti-infection bone tissue engineering scaffold is of very important. In this study, porous titanium alloy bone tissue engineering scaffolds were designed and fabricated by 3D printing. TiO2 nanotubes were further constructed on the scaffolds through electrochemical anodic oxidation, achieving the drug loading and anti-infection functions. The micron-level bionic pores were fabricated by the 3D printing process, and the secondary nanoscale-level nanotubes were achieved through the anodic oxidation process. Thereafter, the micro–nano structured porous bone tissue engineering scaffolds are presented. This structure features that the drug release rate can be regulated by loading the anti-infection drug minocycline and coating them with poly(lactic-co-glycolic acid) (PLGA) in the nanotubes. According to the results, the micro–nano composite porous scaffold showed uniform and controllable micro–nano pores, it may load anti-infection drugs and shown anti-infection ability. In addition, the PLGA coating may delay the drug release and maintain a sustained anti-infection function for the scaffold in a week. This study provides new ideas for designing antibacterial bone tissue engineering scaffold.

Application and Development of Electrospun Nanofiber Scaffolds for Bone Tissue Engineering.

Nanofiber scaffolds have gained significant attention in the field of bone tissue engineering. Electrospinning, a straightforward and efficient technique for producing nanofibers, has been extensively researched. When used in bone tissue engineering scaffolds, electrospun nanofibers with suitable surface properties promote new bone tissue growth and enhance cell adhesion. Recent advancements in electrospinning technology have provided innovative approaches for scaffold fabrication in bone tissue engineering. This review comprehensively examines the utilization of electrospun nanofibers in bone tissue engineering scaffolds and evaluates the relevant literature. The review begins by presenting the fundamental principles and methodologies of electrospinning. It then discusses various materials used in the production of electrospun nanofiber scaffolds for bone tissue engineering, including natural and synthetic polymers, as well as certain inorganic materials. The challenges associated with these materials are also described. The review focuses on novel electrospinning techniques for scaffold construction in bone tissue engineering, such as multilayer nanofibers, multifluid electrospinning, and the integration of electrospinning with other methods. Recent advancements in electrospinning technology have enabled the fabrication of precisely aligned nanofiber scaffolds with nanoscale architectures. These innovative methods also facilitate the fabrication of biomimetic structures, wherein bioactive substances can be incorporated and released in a controlled manner for drug delivery purposes. Moreover, they address issues encountered with traditional electrospun nanofibers, such as mechanical characteristics and biocompatibility. Consequently, the development and implementation of novel electrospinning technologies have revolutionized scaffold fabrication for bone tissue engineering.

Fabrication of 3D chitosan/polyvinyl alcohol/brushite nanofibrous scaffold for bone tissue engineering by electrospinning using a novel falling film collector

Despite its advantages, electrospinning has limited effectiveness in 3D scaffolding due to the high density of fibers it produces. In this research, a novel electrospinning collector was developed to overcome this constraint. An aqueous suspension containing chitosan/polyvinyl alcohol nanofibers was prepared employing a unique falling film collector. Suspension molding by freeze-drying resulted in a 3D nanofibrous scaffold (3D-NF). The mineralized scaffold was obtained by brushite deposition on 3D-NF using wet chemical mineralization by new sodium tripolyphosphate and calcium chloride dihydrate precursors. The 3D-NF was optimized and compared with the conventional electrospun 2D nanofibrous scaffold (2D-NF) and the 3D freeze-dried scaffold (3D-FD). Both minor fibrous and major freeze-dried pore shapes were present in 3D-NFs with sizes of 16.11–24.32 μm and 97.64–234.41 μm, respectively. The scaffolds' porosity increased by 53 % to 73 % compared to 2D-NFs. Besides thermal stability, mineralization improved the 3D-NF's ultimate strength and elastic modulus by 2.2 and 4.7 times, respectively. In vitro cell studies using rat bone marrow mesenchymal cells confirmed cell infiltration up to 290 μm and scaffold biocompatibility. The 3D-NFs given nanofibers and brushite inclusion exhibited considerable osteoinductivity. Therefore, falling film collectors can potentially be applied to prepare 3D-NFs from electrospinning without post-processing.

Production of Agarose-Hydroxyapatite Composites via Supercritical Gel Drying, for Bone Tissue Engineering.

Bone tissue engineering (BTE) is the most promising strategy to repair bones injuries and defects. It relies on the utilization of a temporary support to host the cells and promote nutrient exchange (i.e., the scaffold). Supercritical CO2 assisted drying can preserve scaffold nanostructure, crucial for cell attachment and proliferation. In this work, agarose aerogels, loaded with hydroxyapatite were produced in view of BTE applications. Different combinations of agarose concentration and hydroxyapatite loadings were tested. FESEM and EDX analyses showed that scaffold structure suffered from partial closure when increasing filler concentration; hydroxyapatite distribution was homogenous, and Young's modulus improved. Looking at BTE applications, the optimal combination of agarose and hydroxyapatite resulted to be 1% w/w and 10% w/v, respectively. Mechanical properties showed that the produced composites could be eligible as starting scaffold for BTE, with a Young's Modulus larger than 100 kPa for every blend.

TPMS Microarchitectures for Vertical Bone Augmentation and Osteoconduction: An In Vivo Study.

Triply periodic minimal surface microarchitectures (TPMS) were developed by mathematicians and evolved in all kingdoms of living organisms. Renowned for their lightweight yet robust attributes, TPMS structures find application in diverse fields, such as the construction of satellites, aircrafts, and electric vehicles. Moreover, these microarchitectures, despite their intricate geometric patterns, demonstrate potential for application as bone substitutes, despite the inherent gothic style of natural bone microarchitecture. Here, we produced three TPMS microarchitectures, D-diamond, G-gyroid, and P-primitive, by 3D printing from hydroxyapatite. We explored their mechanical characterization and, further, implanted them to study their bone augmentation and osteoconduction potential. In terms of strength, the D-diamond and G-gyroid performed significantly better than the P-primitive. In a calvarial defect model and a calvarial bone augmentation model, where osteoconduction is determined as the extent of bony bridging of the defect and bone augmentation as the maximal vertical bone ingrowth, the G-gyroid performed significantly better than the P-primitive. No significant difference in performance was observed between the G-gyroid and D-diamond. Since, in real life, the treatment of bone deficiencies in patients comprises elements of defect bridging and bone augmentation, ceramic scaffolds with D-diamond and G-gyroid microarchitectures appear as the best choice for a TPMS-based scaffold in bone tissue engineering.

Tannic acid and quaternized chitosan mediated puerarin-loaded octacalcium phosphate /sodium alginate scaffold for bone tissue engineering

Current limitations in mechanical performance and foreign body reactions (FBR) often lead to implant failure, restricting the application of bioceramic scaffolds. This study presents a novel 3D-printed scaffold that combines the release of anti-inflammatory drugs with osteogenic stimulation. Initially, the inorganic and organic phases were integrated to ensure the scaffold's mechanical integrity through catechol chemistry and the electrostatic interactions between tannic acid and quaternary ammonium chitosan. Subsequently, layers of polydopamine-encapsulated puerarin-loaded zeolitic imidazolate framework-8 (ZIF-8) were self-assembled onto the stent's surface, creating the drug-loaded scaffold that improved drug release without altering the scaffold's structure. Compared with unloaded scaffolds, the puerarin-loaded scaffold demonstrated excellent osteogenic differentiation properties along with superior anti-inflammatory and osteogenic effects in a range of in vitro and in vivo studies. RNA sequencing clarified the role of the TNF and NF/κB signaling pathways in these effects, further supporting the scaffold's osteogenic potential. This study introduces a novel approach for creating drug-loaded scaffolds, providing a unique method for treating cancellous bone defects.

Customized 3D‐printed heterogeneous porous titanium scaffolds for bone tissue engineering

AbstractBone defect is a common clinical disease. Due to the uncertainty of trauma or infection areas, customized size features are often required for bone substitutes. By inspiration of the natural bone structure, this study designs porous scaffolds with a biomimetic design perspective by using different inner and outer pore units. The outer pore units adopt body‐centered cubic (BCC) structure to simulate the weight‐bearing function of human cortical bone, while inner pore units using I‐Wrapped Package structure, a kind of three periods minimum surface, to obtain a good permeability and simulates the inner layer of cancellous bone. To further regulate the overall modulus of the scaffold within the range of natural bone modulus in the human body, the scaffold was designed to axial gradient structure. Compression experiments were conducted, and the results indicated that when the volume fraction linearly increased from 20% to 50%, the Young's modulus was close to the cortical bone modulus in the human body. In vitro cell experiments further proved that osteoblasts have good cellular activity and spreading morphology on the surface of this scaffold. The customized 3D‐printed heterogeneous porous titanium scaffold has great application potential in bone tissue engineering.

Chitosan-incorporated Bioceramic-based Nanomaterials for Localized Release of Therapeutics and Bone Regeneration: An Overview of Recent Advances and Progresses

Abstract: The usage of nanoparticles in tissue engineering applications has increased significantly in the last several years. Functional tissues are developed by regulating cell proliferation, differentiation, and migration on nanostructured scaffolds containing cells. These scaffolds provide an environment that is more structurally supportive than the microarchitecture of natural bone. Given its exceptional properties, such as its osteogenic potential, biocompatibility, and biodegradability, chitosan is a good and promising biomaterial. Unfortunately, chitosan's low mechanical strength makes it unsuitable for load-bearing applications. By mixing chitosan with other biomaterials, this drawback might be mitigated. Bone tissue engineering uses both bioresorbable materials like tricalcium phosphate and bioactive materials like hydroxyapatite and bioglass. Alumina and titanium are examples of bioinert materials that are part of these bioceramics. When produced at nanoscale scales, these materials have a larger surface area and better cell adhesion. This review paper will go into great detail on the bioinert, bioresorbable, and bioactive nanoceramics-reinforced chitosan scaffolds for bone tissue engineering.

Potential use of a bone tissue engineering scaffold based on electrospun poly (ɛ-caprolactone) - Poly (vinyl alcohol) hybrid nanofibers containing modified cockle shell nanopowder

Today, the construction of scaffolds promoting the differentiation of stem cells is an intelligent innovation that accelerates the differentiation toward the target tissue. The use of calcium and phosphate compounds is capable of elevating the precision and efficiency of the osteogenic differentiation of stem cells. In this research, osteoconductive electrospun poly (ɛ-caprolactone) (PCL) - poly (vinyl alcohol) (PVA) hybrid nanofibrous scaffolds containing modified cockle shell (CS) nanopowder were prepared and investigated. In this regard, the modified CS nanopowder was prepared by grinding and modifying with phosphoric acid, and it was then added to PVA nanofibers at different weight percentages. Based on the SEM images, the optimum content of the modified CS nanopowder was set at 7 wt %, since reaching the threshold of agglomeration restricted this incorporation. In the second step, the PVA-CS7 nanofibrous sample was hybridized with different PCL ratios. Concerning the hydrophilicity and mechanical strength, the sample named PCL50-PVA50-CS7 was ultimately selected as the optimized and suitable candidate scaffold for bone tissue application. The accelerated hydrolytic degradation of the sample was also studied by FTIR and SEM analyses, and the results confirmed that the mineral deposits of CS are available approximately 7 days for mesenchymal stem cells. Moreover, Alizarin red staining illustrated that the presence of CS in the PCL50-PVA50-CS7 hybrid nanofibrous scaffold may potentially lead to an increase in calcium deposits with high precipitates, authenticating the differentiation of stem cells towards osteogenic cells.

Gelatin-containing functionally graded calcium sulfate/bioactive glass bone tissue engineering scaffold

One of the challenges and limitations of bone tissue engineering includes fast degradation rates, reduced bioactivity, donor site morbidity, and unresolved risks of pathogen transmission. In the field of bone tissue engineering, gradient materials are promising for treating bone defects because they can create graded structures and compositions similar to natural bone. By controlling the amount of components in the structure, the degradation rate, bioactivity, and osteogenic capacity can be manipulated. In the current study, a gradient, multilayer, porous nanocomposite of calcium sulfate/glass (Gn CS/BG) with a gelatin coating (Gn CS/BG-Gel) was prepared using rotational casting technique. The SEM results showed an average pore size of approximately 400 μm within the Gn CS/BG-Gel nanocomposite. An elastic modulus (E) of around 240 MPa and an ultimate tensile strength (σ) of approximately 5.5 MPa were achieved for Gn CS/BG-Gel nanocomposite. The degradation analysis in a dynamic tris-buffer environment revealed a degradation rate of 68 % over a 63-day period, with a decrease in degradation rate as the bioactive glass (BG) content increased in each layer, indicating the influence of BG on the degradation process. The bioactivity results in a dynamic simulated body fluid suggested that increased BG content in each layer promoted hydroxyapatite formation, indicating improved bioactive behavior. The evaluation of ion release with ICP-OES, MTT and Acridine Orange assays using human bone marrow-derived mesenchymal stem cells (hBMSCs) confirmed the non-toxic nature of Gn CS/BG-Gel. Assessments of alkaline phosphatase (ALP) activity, calcium content, Alizarin Red staining and cell attachment behavior substantiated the osteogenic potential of Gn CS/BG-Gel. Collectively, the three-dimensional structure along with the Gn CS/BG-Gel composition contributed to the enhanced cellular responses. These findings hold significant promise for the development of biomaterials with potential applications in bone tissue engineering, and they contribute valuable insights to the field.

Cell Instructive Behavior of Composite Scaffolds in a Co-Culture of Human Mesenchymal Stem Cells and Peripheral Blood Mononuclear Cells.

The in vitro evaluation of 3D scaffolds for bone tissue engineering in mono-cultures is a common practice; however, it does not represent the native complex nature of bone tissue. Co-cultures of osteoblasts and osteoclasts, without the addition of stimulating agents for monitoring cellular cross-talk, remains a challenge. In this study, a growth factor-free co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) has been established and used for the evaluation of 3D-printed scaffolds for bone tissue engineering. The scaffolds were produced from PLLA/PCL/PHBV polymeric blends, with two composite materials produced through the addition of 2.5% w/v nanohydroxyapatite (nHA) or strontium-substituted nanohydroxyapatite (Sr-nHA). Cell morphology data showed that hPBMCs remained undifferentiated in co-culture, while no obvious differences were observed in the mono- and co-cultures of hBM-MSCs. A significantly increased alkaline phosphatase (ALP) activity and osteogenic gene expression was observed in co-culture on Sr-nHA-containing scaffolds. Tartrate-resistant acid phosphatase (TRAP) activity and osteoclastogenic gene expression displayed significantly suppressed levels in co-culture on Sr-nHA-containing scaffolds. Interestingly, mono-cultures of hPBMCs on Sr-nHA-containing scaffolds indicated a delay in osteoclasts formation, as evidenced from TRAP activity and gene expression, demonstrating that strontium acts as an osteoclastogenesis inhibitor. This co-culture study presents an effective 3D model to evaluate the regenerative capacity of scaffolds for bone tissue engineering, thus minimizing time-consuming and costly in vivo experiments.