Scaffold System Research Articles

Protective effects of resveratrol against PM2.5-induced damage in hNSCs and its mitigation of PM2.5-induced mitochondrial dysfunction in a 3D scaffold system.

Exposure to PM2.5 is associated with neurotoxicity and mitochondrial dysfunction. Resveratrol, a natural polyphenol, has demonstrated antioxidant and neuroprotective properties. Still, its efficacy in mitigating PM2.5-induced damage in human neural stem cells (hNSCs) and within a 3D scaffold system remains underexplored. This study investigated the protective effects of resveratrol against PM2.5-induced damage in hNSCs and within a 3D scaffold system. Assess cell viability using MTT and LIVE/DEAD assays and measure caspase activity by fluorescence analysis. Quantify gene and protein expression of key regulatory pathways using qPCR and Western blotting. Then, mitochondrial function was analyzed by measuring ATP production, mitochondrial mass, maximal respiratory rate, COX activity, membrane potential, TEM, and immunofluorescence staining. In addition, 3D scaffolds created by the CELLINK INKREDIBLE bioprinter were used to study the effect of resveratrol on PM2.5-induced hNSCs damage. Resveratrol significantly improved cell viability and reduced caspase-3 and caspase-9 activities in PM2.5-treated hNSCs. Resveratrol treatment upregulated TrKBR, PI3K, AKT, CREB, PPARα, PPARγ, SIRT1and AMPK expression. It restored mitochondrial function by increasing ATP production, mitochondrial mass, maximal respiratory rate, COX activity, and membrane potential. Using a 3D scaffold demonstrated resveratrol's potential to maintain mitochondrial function and cellular health under PM2.5 exposure. Resveratrol can effectively reduce neurotoxicity and mitochondrial dysfunction caused by PM2.5 in hNSCs. Its protective effects against PM2.5-induced toxicity in hNSCs within a 3D bioprinted model highlight this study's translational potential. These findings emphasize its potential as a therapeutic agent against environmental neurotoxins and the development of neuroprotective strategies.

3D bioprinted poly(lactic acid) scaffolds infused with curcumin-loaded nanostructured lipid carriers: a promising approach for skin regeneration.

Nanotechnology and 3D bioprinted scaffolds are revolutionizing the field of wound healing and skin regeneration. By facilitating proper cellular movement and providing a customizable structure that replicates the extracellular matrix, such technologies not only expedite the healing process but also ensure the seamless integration of new skin layers, enhancing tissue repair and promoting overall cell growth. This study centres on the creation and assessment of a nanostructured lipid carrier containing curcumin (CNLC), which is integrated into a 3D bioprinted PLA scaffold system. The goal is to investigate its potential as a vehicle for delivering poorly soluble curcumin for enhanced wound healing. The developed CNLC exhibited an oval morphology and average particle size of 292 nm. The entrapment efficiency (EE) was 81.37 ± 0.85%, and the drug loading capacity was 6.59 ± 1.61%. CNLC was then integrated into PLA-based 3D bioprinted scaffolds, and physicochemical analyses were conducted to evaluate their properties. Cell viability studies carried out using fibroblast cells demonstrated that the PLA/CNLC scaffolds are non-cytotoxic. In vivo experiments showed that the PLA/CNLC scaffolds exhibited complete wound contraction and closure of full-thickness wounds within a period of 21 days. The findings confirmed the scaffold's capacity as a tool for accelerating wound healing. The research emphasises the need for using biomimetic 3D printed scaffold materials and the promise of nanobiotechnology in enhancing treatment efficacy.

Oyster Shell Powder/PCL Composite Scaffolds Loaded with Psoralen Nanospheres Promote Large Bone Defect Repair.

Research on bone substitutes for repairing bone defects has drawn increasing attention, and the efficacy of three-dimensional (3D) printed bioactive porous scaffolds for bone defect repair has been well documented. Our previous studies have shown that psoralen can promote osteogenesis by activating the Wnt/β-catenin and BMP/Smad signaling pathways and their crosstalk effects, and psoralen nanospheres have a good osteogenesis-promoting effect in vitro with low cytotoxicity. The Chinese medicine oyster shell powder, characterized by its porous structure, strong adsorption, and unique bioactivity, has potential in fracture-promoting repair materials. However, the effect of loading psoralen nanospheres onto oyster shell powder/polycaprolactone (OSP/PCL) scaffolds to repair bone defects is unclear. In this study, composite scaffolds consisting of OSP PCL were prepared by 3D printing, and psoralen nanospheres were adhered to the scaffolds. The characterization features of the composite scaffold system were investigated in vitro concerning the biocompatibility of bone mesenchymal stem cells (BMSCs). The efficacy of the composite scaffolds for repairing bone defects was explored in vivo through a rat cranial bone defect model. The results showed that the composite scaffolds were homogeneous porous structures with high mechanical strength and could be adhered well by the psoralen-loaded nanospheres. In vitro studies showed that the scaffolds had good biocompatibility with BMSCs and positively affected the expression of osteogenic differentiation-related proteins. In vivo studies showed that the composite scaffolds could more effectively promote the formation of new bone in the defect area (Φ5 mm) compared to the pure PCL scaffolds. At the same time, the composite scaffolds containing psoralen had a more significant stimulating effect on the healing of the cranial defects compared with the OSP/PCL scaffolds without psoralen.

Local delivery of mesenchymal stem cell-extruded nanovesicles through a bio-responsive scaffold for acute spinal cord injury treatment.

Intense inflammatory responses and elevated levels of reactive oxygen species (ROS) extremely exacerbate the pathological process of spinal cord injury (SCI). Mesenchymal stem cell (MSC)-derived extracellular vesicles (EV) can mitigate SCI-related inflammation but their production yield remains limited. Alternatively, MSC-extruded nanovesicles (NV) inherit the therapeutic potential from MSCs and have a markedly higher yield than EV. In the present study, a bio-responsive scaffold system (RS + NV) was created for SCI treatment. NV was generated from human MSCs by physical extrusion and encapsulated in a ROS-responsive scaffold (RS). RS + NV efficiently scavenged environmental ROS and underwent degradation, thus facilitating the responsive release of NV. NV inhibited the pro-inflammatory phenotypic transformation, and reduced the secretion of TNF-α and IL-6 from lipopolysaccharide-stimulated BV2 cells, exhibiting comparable anti-inflammatory properties to EV. Additionally, NV posed a superior antioxidative effect than EV and could effectively alleviate the oxidative stress damage of H2O2-stimulated PC12 cells. Furthermore, in SCI rats, the uptake of NV was primarily attributed to microglia and neurons. RS + NV exhibited synergistic effects in regulating the hostile microenvironment in vivo during the acute phase, thereby establishing a conducive environment for long-term locomotor, tissue repair, and recovery of neuropathic pain. Overall, RS + NV shows promising potential for use as an anti-inflammatory and antioxidative therapeutic approach for treating SCI.

Engineering high-activity crosslinked enzyme aggregates via SpyCatcher/SpyTag-mediated self-assembly.

Crosslinked Enzyme Aggregates (CLEAs) are favored for their operational stability and recyclability. However, the traditional CLEAs preparation may distort the enzyme's active site and reduce activity. Therefore, we developed a universally applicable crosslinked SpyCatcher scaffold system designed for the facile preparation of CLEAs. Four lysine residues were introduced to the N-terminus of SpyCatcher to enhance the crosslinking selectivity with glutaraldehyde. This scaffold subsequently enables the assembly of enzymes through the specific binding affinity between SpyTag and SpyCatcher. By precipitating SpyCatcher with (NH4)2SO4 at a 1:2 (v/v) ratio at 4°C for 1h, followed by crosslinking with glutaraldehyde at 25°C and 100rpm for 3h, the SpyCatcher scaffold achieved a crosslinking efficiency exceeding 90%. Utilizing this approach for the immobilization of SpyTaged enzymes to construct xylanase-CLEAs (X-CLEAs) and cellulase-CLEAs (C-CLEAs) highlighted the accurate construction the enzyme complex. Furthermore, C-CLEAs retained approximately 90% activity after 3cycles and over 50% activity after 10cycles, demonstrating good operational stability and reusability. C-CLEAs achieved a 1.6-fold more reducing sugars in corn stover hydrolysis compared to free enzymes. This suggests that the close proximity within CLEAs provided an advantage for the enzymatic cascade reaction, highlighting the potential application of CLEAs in various fields.

Problems of monitoring critical elements of scaffolding

Scaffolds are temporary structures that include anchors, elements, and platforms that are used during the construction of steel or concrete structures to support equipment or workers at height. Since these structures have aimed to guarantee safety and support workers at heights, the stability of scaffold systems is of significant importance. These systems have some disadvantages. For example, they are sensitive to vibrations. This feature reduces their stability under service-, cyclic-, or earthquake loadings. Furthermore, the vibrating nature of scaffolds can impose additional axial loads and consequently additional moment loads on the scaffold columns and decrease the safety of workers and increase the accidents of use of them. In this paper, a review of some research has been performed that aimed to solve this problem and improve the stability of scaffolds. These articles have investigated the behaviour of anchors and joints and the influence of imperfections and inaccuracies on scaffolds. A summary of research has been presented that has proposed new methods for predicting the behaviour, damage, and collapse of scaffolds using some structural health monitoring (SHM) methods. Finally, the research gaps and limitations of previous studies have been investigated, with a focus on monitoring and solving the problems of the scaffolds and critical elements so that these problems can be solved and evaluated in future studies.

3D-printed zinc oxide nanoparticles modified barium titanate/hydroxyapatite ultrasound-responsive piezoelectric ceramic composite scaffold for treating infected bone defects

Clinically, infectious bone defects represent a significant threat, leading to osteonecrosis, severely compromising patient prognosis, and prolonging hospital stays. Thus, there is an urgent need to develop a bone graft substitute that combines broad-spectrum antibacterial efficacy and bone-inductive properties, providing an effective treatment option for infectious bone defects. In this study, the precision of digital light processing (DLP) 3D printing technology was utilized to construct a scaffold, incorporating zinc oxide nanoparticles (ZnO-NPs) modified barium titanate (BT) with hydroxyapatite (HA), resulting in a piezoelectric ceramic scaffold designed for the repair of infected bone defects. The results indicated that the addition of ZnO-NPs significantly improved the piezoelectric properties of BT, facilitating a higher HA content within the ceramic scaffold system, which is essential for bone regeneration. In vitro antibacterial assessments highlighted the scaffold's potent antibacterial capabilities. Moreover, combining the synergistic effects of low-intensity pulsed ultrasound (LIPUS) and piezoelectricity, results demonstrated that the scaffold promoted notable osteogenic and angiogenic potential, enhancing bone growth and repair. Furthermore, transcriptomics analysis results suggested that the early growth response-1 (EGR1) gene might be crucial in this process. This study introduces a novel method for constructing piezoelectric ceramic scaffolds exhibiting outstanding osteogenic, angiogenic, and antibacterial properties under the combined influence of LIPUS, offering a promising treatment strategy for infectious bone defects.

Modified genetic algorithm for efficient optimization: application to prestressed concrete structural elements

Prestressing, whether bonded or non-bonded, has become increasingly attractive as it allows for larger spans, greater architectural flexibility, greater agility in execution and greater durability. All of these advantages are capable of making prestressed concrete structures more economical solutions when associated with an efficient scaffolding system and formwork. The use of prestressed beams combined with ribbed slabs allows the slabs and beams to have the same height, thus favoring the architecture, in addition to facilitating the assembly of formwork and concreting. The designer can appropriately define the dimensions of the beams and slabs, as well as parameters such as the quantity and layout of cables by trial based on experience. However, the use of numerical optimization techniques are tools recognized as appropriate for the search for a structural solution, where design parameters, whether at the level of design (topology), intermediate (shape) or detail (dimension), can be determined such that the solution minimizes a performance measure, for example, cost, which takes into account the cost of materials, the volume of concrete, the weight of passive and active reinforcement, and labor productivity. Given the discrete nature of some variables, genetic algorithms (GA) have been widely used. GAs have control parameters and operators that are, in general, dependent on the problem, requiring calibrations in each case. The objective of this work is to review some optimization models and improve the GA of the BIOS program - developed at the (Computational Mechanics and Visualization Laboratory) LMCV of the Federal University of Ceará (UFC) - investigating new operators, thus aiming at the efficiency of the algorithm for prestressed elements, using a prestressed band beam as a case study. Genetic operators, in particular crossover, will be targets of the study.

Novel Injectable Collagen/Glycerol/Pullulan Gel Promotes Osteogenic Differentiation of Mesenchymal Stem Cells and the Repair of Rat Cranial Defects.

Bone tissue engineering is a technique that simulates the bone tissue microenvironment by utilizing cells, tissue scaffolds, and growth factors. The collagen hydrogel is a three-dimensional network bionic material that has properties and structures comparable to those of the extracellular matrix (ECM), making it an ideal scaffold and drug delivery system for tissue engineering. The clinical applications of this material are restricted due to its low mechanical strength. In this investigation, a collagen-based gel (atelocollagen/glycerol/pullulan [Col/Gly/Pul] gel) that is moldable and injectable with high adhesive qualities was created by employing a straightforward technique that involved the introduction of Gly and Pul. This study aimed to characterize the internal morphology and chemical composition of the Col/Gly/Pul gel, as well as to verify its osteogenic properties through in vivo and in vitro experiments. When compared to a standard pure Col hydrogel, this material is more adaptable to the complexity of the local environment of bone defects and the apposition of irregularly shaped flaws due to its greater mechanical strength, injectability, and moldability. Overall, the Col/Gly/Pul gel is an implant that shows great potential for the treatment of complex bone defects and the enhancement of bone regeneration.

Engineered Osteochondral Scaffolds with Bioactive Cartilage Zone for Enhanced Articular Cartilage Regeneration.

Despite progress, osteochondral (OC) tissue engineering strategies face limitations in terms of articular cartilage layer development and its integration with the underlying bone tissue. The main objective of this study is to develop a zonal OC scaffold with native biochemical signaling in the cartilage zone to promote articular cartilage development devoid of cells and growth factors. Herein, we report the development and in vivo assessment of a novel gradient and zonal-structured scaffold for OC defect regeneration. The scaffold system is composed of a mechanically supportive 3D-printed template containing decellularized cartilage extracellular matrix (ECM) biomaterial in the cartilage zone that possesses bioactive characteristics, such as chemotactic activity and native tissue biochemical composition. OC scaffolds with a bioactive cartilage zone were implanted in vivo in a rabbit osteochondral defect model and assessed for gross morphology, matrix deposition, cellular distribution, and overall tissue regeneration. The scaffold system supported recruitment and infiltration of host cells into the cartilage zone of the graft, which led to increased ECM deposition and physiologically relevant articular cartilage tissue formation. Semi-quantitative ICRS scoring (overall score double for OC scaffold with bioactive cartilage zone compared to PLA scaffold) further confirm the bioactive scaffold enhanced articular cartilage engineering. This strategy of designing bioactive scaffolds to promote endogenous cellular infiltration can be a much simpler and effective approach for OC tissue repair and regeneration.

Carbon Based Polymeric Nanocomposite Hydrogel Bioink: A Review.

Carbon-based polymeric nanocomposite hydrogels (NCHs) represent a groundbreaking advancement in biomedical materials by integrating nanoparticles such as graphene, carbon nanotubes (CNTs), carbon dots (CDs), and activated charcoal (AC) into polymeric matrices. These nanocomposites significantly enhance the mechanical strength, electrical conductivity, and bioactivity of hydrogels, making them highly effective for drug delivery, tissue engineering (TE), bioinks for 3D Bioprinting, and wound healing applications. Graphene improves the mechanical and electrical properties of hydrogels, facilitating advanced tissue scaffolding and drug delivery systems. CNTs, with their exceptional mechanical strength and conductivity, enhance rheological properties, facilitating their use as bioinks in supporting complex 3D bioprinting tasks for neural, bone, and cardiac tissues by mimicking the natural structure of tissues. CDs offer fluorescence capabilities for theranostic applications, integrating imaging and therapeutic functions. AC enhances mechanical strength, biocompatibility, and antibacterial effectiveness, making it suitable for wound healing and electroactive scaffolds. Despite these promising features, challenges remain, such as optimizing nanoparticle concentrations, ensuring biocompatibility, achieving uniform dispersion, scaling up production, and integrating multiple functionalities. Addressing these challenges through continued research and development is crucial for advancing the clinical and industrial applications of these innovative hydrogels.

Design of patient-specific mandibular reconstruction plates and a hybrid scaffold

Background:Managing segmental mandibular defects remains challenging, requiring a multidisciplinary approach despite the remarkable progress in mandibular reconstruction plates, finite element methods, computer-aided design and manufacturing techniques, and novel surgical procedures. Complex surgeries require a comprehensive approach, as using only reconstruction plates or tissue scaffolds may not be adequate for optimal results. The limitations of the treatment options should be investigated towards a patient-specific trend to provide shorter surgery time, better healing, and lower costs. Integrated hybrid scaffold systems are promising in improving mechanical properties and facilitating healing. By combining different materials and structures, hybrid scaffolds can provide enhanced support and stability to the tissue regeneration process, leading to better patient outcomes. The use of such systems represents a significant advancement in tissue engineering and a wide range of medical procedures. Materials and Methods:A head and neck computed tomography (CT) data of a patient with odontogenic myxoma was used for creating a three-dimensional (3D) mandible model. Virtual osteotomies were performed to create a segmental defect model, including the angulus mandibulae region. The first mandibular reconstruction plate was designed. Finite elemental analyses (FEA) and topology optimizations were performed to create two different reconstruction plates for different treatment scenarios. The FEA were performed for the resulting two plates to assess their biomechanical performance. To provide osteoconductive and osteoinductive properties a scaffold was designed using the defect area. A biomimetic Tricalcium phosphate-Polycaprolactone (TCP-PCL) hybrid bone scaffold enhanced with Hyaluronic acid dipping was manufactured. Results:The results of the in-silico analysis indicate that the designed reconstruction plates possess robust biomechanical performance and demonstrate remarkable stability under the most rigorous masticatory activities. Using the Voronoi pattern decreased the mass by %37 without losing endurance. Using reconstruction plates and hybrid scaffolds exhibits promising potential for clinical applications, subject to further in vivo and clinical studies.

Enhanced Bioactivity of Chitosan-Alginate-Riboflavin Liquid-Exfoliated Molybdenum Disulfide Nanosheets for Bone Tissue Engineering Applications.

Bone tissue engineering is a growing field that provides solutions for the treatment of bone deformities, injuries, diseases, and anomalies by replacing autograft and allograft procedures. Various scaffolding materials have been used for the construction of bone tissue, including metals, ceramics, and polymers. This study investigates an innovative liquid exfoliation approach for the production of molybdenum disulfide (MoS2) nanosheets using riboflavin (RF-MoS2) as an exfoliation agent and subsequently analytically characterized for the development of bone scaffolding system. UV analysis of RF-MoS2 shows the absorbance spectra at 610 and 668 nm and the particle size was 123 ± 4 nm and a surface charge of -16.1 ± 2 mV. Further, alginate-chitosan (Alg-Chi) and alginate-chitosan-riboflavin-MoS2 (Alg-Chi-RF-MoS2) nanocomposite scaffolds were developed. The morphology of the Alg-Chi-RF-MoS2 scaffold was studied using scanning electron microscopy and pore size was found to be 210 ± 10 μm. Alg-Chi-RF-MoS2 scaffolds generate calcium phosphate biominerals when immersed in a simulated body fluid. Alg-Chi and Alg-Chi-RF-MoS2 scaffolds were biocompatible with C3H10T1/2 cells, and scaffolds showed a significant increase in alkaline phosphatase and mineralization. Thus, the developed Alg-Chi-RF-MoS2 scaffold proved to be an appropriate artificial graft for bone graft substitution.

Injectable Photocrosslinked Hydrogel Dressing Encapsulating Quercetin-Loaded Zeolitic Imidazolate Framework-8 for Skin Wound Healing.

Background: Wound management is a critical component of clinical practice. Promoting timely healing of wounds is essential for patient recovery. Traditional treatments have limited efficacy due to prolonged healing times, excessive inflammatory responses, and susceptibility to infection. Methods: In this research, we created an injectable hydrogel wound dressing formulated from gelatin methacryloyl (GelMA) that encapsulates quercetin-loaded zeolitic imidazolate framework-8 (Qu@ZIF-8) nanoparticles. Next, its ability to promote skin wound healing was validated through in vitro experiments and animal studies. Results: Research conducted both in vitro and in vivo indicated that this hydrogel dressing effectively mitigates inflammation, inhibits bacterial growth, and promotes angiogenesis and collagen synthesis, thus facilitating a safe and efficient healing process for wounds. Conclusions: This cutting-edge scaffold system provides a novel strategy for wound repair and demonstrates significant potential for clinical applications.

Mechanically enhanced biodegradable scaffold based on SF microfibers for repairing bone defects in the distal femur of rats

Silk-based biodegradable materials play an important role in tissue engineering, especially in the field of bone regeneration. However, while optimizing mechanical properties and bone regeneration characteristics, modified silk fibroin (SF)-based materials also increase the complexity of scaffold systems, which is not conducive to clinical translation. In this study, we first added synthetic biomimetic mineralized collagen (MC) particles to SF-based materials to improve the bone regeneration properties of the scaffolds and simultaneously regulated the degradation rate of the scaffolds to match the bone regeneration rate. Second, SF microfibers were prepared by hydrolysis with alkaline heating and added to SFMC scaffolds with excellent osteogenic stimulation ability to prepare SF microfiber (mf)-modified SFMC-mf scaffolds with excellent mechanical properties, whose compression modulus increased from 4.58±0.23 MPa to 14.63±0.88 MPa. Finally, the SFMC-mf scaffold was implanted into the weight-bearing bone defect area of the distal femur of rats, and the results showed that the SFMC-mf scaffold significantly promoted functional recovery of the affected limb and increased the amount of new bone in the defect area compared with those in the SFC-mf group and the blank control group. In addition, the RNA-seq results suggested that the genes with upregulated expression in the SFMC-mf scaffold group were mainly enriched in vascular regeneration. In conclusion, this SF microfiber modification method effectively improved the mechanical properties of SFMC scaffolds without moving the SF scaffold system in the direction of compositional complexity, providing new insights for the subsequent development of more effective bionic repair materials for bone defects and assisting in their clinical translation.

Design of a Genetically Programmable and Customizable Protein Scaffolding System for the Hierarchical Assembly of Robust, Functional Macroscale Materials.

Inspired by the properties of natural protein-based biomaterials, protein nanomaterials are increasingly designed with natural or engineered peptides or with protein building blocks. Few examples describe the design of functional protein-based materials for biotechnological applications that can be readily manufactured, are amenable to functionalization, and exhibit robust assembly properties for macroscale material formation. Here, we designed a protein-scaffolding system that self-assembles into robust, macroscale materials suitable for in vitro cell-free applications. By controlling the coexpression in Escherichia coli of self-assembling scaffold building blocks with and without modifications for covalent attachment of cross-linking cargo proteins, hybrid scaffolds with spatially organized conjugation sites are overproduced that can be readily isolated. Cargo proteins, including enzymes, are rapidly cross-linked onto scaffolds for the formation of functional materials. We show that these materials can be used for the in vitro operation of a coimmobilized two-enzyme reaction and that the protein material can be recovered and reused. We believe that this work will provide a versatile platform for the design and scalable production of functional materials with customizable properties and the robustness required for biotechnological applications.

Extracellular vesicle-laden hybrid cryogel-interpenetrating network scaffold for improved osteogenesis in bone tissue engineering

Bone tissue engineering (BTE) aims to regenerate the damaged or diseased bone by combining cells, growth factors, and biomaterials. Synthetic bone tissue, which is widely available, is a promising alternative to autografts, allografts, and natural fillers. Biomaterials like 3D scaffolds mimic the extracellular matrix, supporting cell growth and tissue regeneration. However, clinical applications face challenges such as limited osteogenic and angiogenic capabilities, weak mechanical strength, and risks of infection and immune reactions. The current work introduces a mechanically robust cryogel-hydrogel hybrid scaffold, loaded with extracellular vesicles (EVs) and cell secretomes as osteoinductive cues. The scaffold’s mechanical strength was assessed against its individual components. Its physical characteristics, including swelling capacity and porous structure, were analyzed using field emission scanning electron microscopy (FESEM), and the incorporation of nano-hydroxyapatite (nHAp) was confirmed through Fourier transform infrared (FTIR) spectroscopy. Three scaffolds were tested: a cryogel scaffold of gelatin and nano-hydroxyapatite (nHAp), a hydrogel scaffold of poly(ethylene glycol) diacrylate (PEGDA), and a hybrid cryogel scaffold of gelatin and nano-hydroxyapatite with a PEGDA interpenetrating network (IPN). The results indicated that the hybrid cryogel scaffold with IPN had the greatest normalized ALP content and lowest cytotoxicity, making it the best choice for further study. To explore the osteoinductive potential of Mesenchymal Stem Cell-derived EVs, three scaffold variations were tested: a hybrid IPN scaffold, IPN + nHAp scaffold, and IPN + nHAp + EVs scaffold. These were evaluated for viable cell count, ALP activity, DNA content, and calcium accumulation. The IPN + nHAp + EVs scaffold demonstrated the greatest potential for BTE, with the highest mechanical strength—20.82-fold greater than the single-network cryogel and 1.75-fold stronger than the PEGDA hydrogel. It also showed the highest normalized ALP content, 3.39-fold and 1.47-fold greater than the IPN and IPN + nHAp scaffolds, respectively, and the highest calcium deposition, 1.30-fold higher than the IPN + nHAp scaffold. In conclusion, this study successfully developed a hybrid scaffold system with improved mechanical characteristics and osteogenesis potential, advancing the field of bone tissue engineering.

Development of PCL/PVA/PCL Scaffold for Local Delivery of Calcium Fructoborate for Bone Tissue Engineering

Calcium fructoborate (CaFB) has gathered attention due to its boron and calcium content, both of which are known to support bone health, deposition and regeneration. Previous studies have shown that CaFB has a positive effect on bone health and has been proven to promote bone-like properties. In light of this information, a local CaFB delivering scaffold could improve bone regeneration in cases of bone tissue loss. This study aimed to design a layer-by-layer polymeric sponge capable of achieving controlled local delivery of CaFB to improve bone tissue healing. The dose-dependent effect of CaFB on the cell viability of the Saos-2 cell line was investigated in vitro. Layer by-layer structure of the polymeric scaffold supported controlled release of CaFB, with 33.9±7.4% released after 7 days of incubation. CaFB at 31.25 μg/mL concentration was able to improve Saos-2 cell viability up to 174.7±24.1% and 127.7±8.7% after 1 and 4 days of incubation. After 7 days of incubation CaFB treatment at concentrations of 250, 125, 62.5 and 31.25 μg/mL improved cell viability up to 194.3±47.7, 155.3±17.7, 149.4±5.4 and 132.5±13.3%. The polycaprolactone/polyvinyl alcohol/polycaprolactonen(PCL/PVA/PCL) scaffold supported the viability of cells for 7 days and was shown to be biocompatible. The results of this study showed that CaFB is a potential compound thatncan be locally delivered within a scaffold system to improve bone tissue regeneration.

Incorporation of small extracellular vesicles in PEG/HA-Bio-Oss hydrogel composite scaffold for bone regeneration

Stem cell derived small extracellular vesicles (sEVs) have emerged as promising nanomaterials for the repair of bone defects. However, low retention of sEVs affects their therapeutic effects. Clinically used natural substitute inorganic bovine bone mineral (Bio-Oss) bone powder lacks high compactibility and efficient osteo-inductivity that limit its clinical application in repairing large bone defects. In this study, a poly ethylene glycol/hyaluronic acid (PEG/HA) hydrogel was used to stabilize Bio-Oss and incorporate rat bone marrow stem cell-derived sEVs (rBMSCs-sEVs) to engineer a PEG/HA-Bio-Oss (PEG/HA-Bio) composite scaffold. Encapsulation and sustained release of sEVs in hydrogel scaffold can enhance the retention of sEVs in targeted area, achieving long-lasting repair effect. Meanwhile, synergistic administration of sEVs and Bio-Oss in cranial defect can improve therapeutic effects. The PEG/HA-Bio composite scaffold showed good mechanical properties and biocompatibility, supporting the growth of rBMSCs. Furthermore, sEVs enhancedin vitrocell proliferation and osteogenic differentiation of rBMSCs. Implantation of sEVs/PEG/HA-Bio in rat cranial defect model promotedin vivobone regeneration, suggesting the great potential of sEVs/PEG/HA-Bio composite scaffold for bone repair and regeneration. Overall, this work provides a strategy of combining hydrogel composite scaffold systems and stem cell-derived sEVs for the application of tissue engineering repair.

Development of multi-layered three-dimensional printed scaffold for sequential delivery of biomolecules

Spatiotemporal control of exogenous growth factors plays a crucial role in the sequential repair of damaged tissues. However, traditional therapeutic trials have mostly relied on the delivery of a single molecule because of the limitations of rapid diffusion and the instability of biomolecules. In this study, we developed a novel strategy using a composite of gelatin and silica as an alternative for the stable and sequential release of biomolecules. Two biomolecules, basic fibroblast growth factor and bone morphogenetic protein-2, were incorporated into two separate composites and sequentially layered onto the activated polymer surface. Each molecule was sequentially released from each layer of the scaffold and the silica composite prevented rapid diffusion owing to its nano-porous structure. The adhesion, proliferation, and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells were significantly enhanced in the double-layered group containing separately delivered dual molecules compared with the control or single groups. Our developed gelatin–silica composite was successfully placed in double layers on polymer scaffolds, and cellular responses were promoted in this manner. These results demonstrated that our scaffolding system has potential as a therapeutic strategy for the delivery of dual or multiple biomolecules in regenerative medicine.