A novel label-free electrochemical immunosensor for the detection of heat shock protein 70 of lung adenocarcinoma cell line following paclitaxel treatment using l-cysteine-functionalized Au@MnO2/MoO3 nanocomposites

The future trend in achieving precision medicine involves the development of non-invasive cancer biomarker sensors that offer high accuracy, low cost, and time-saving benefits for risk clarification, early detection, disease detection, and therapeutic monitoring. A facile approach for the synthesis of MoO3 nanosheets was developed by thermally oxidizing MoS2 nanosheets in air followed by thermal annealing. Subsequently, Au@MnO2 nanocomposites were prepared using a combined hydrothermal process and in situ chemical synthesis. In this study, we present a novel immunosensor design strategy involving the immobilization of antiHSP70 antibodies on Au@MnO2/MoO3 nanocomposites modified on a screen-printed electrode (SPE) using EDC/NHS chemistry. This study establishes HSP70 as a potential biomarker for monitoring therapeutic response during anticancer therapy. Impedance measurements of HSP70 on the Au@MnO2/MoO3/SPE immunosensor using EIS showed an increase in impedance with an increase in HSP70 concentration. The electrochemical immunosensor demonstrated a good linear response in the range of 0.001 to 1000 ng mL-1 with a detection limit of 0.17 pg mL-1 under optimal conditions. Moreover, the immunosensor was effective in detecting HSP70 at low concentrations in a lung adenocarcinoma cell line following Paclitaxel treatment, indicating its potential for early detection of the HSP70 biomarker in organ-on-a-chip and clinical applications.

The exosomal secretomes of mesenchymal stem cells extracted via 3D-printed lithium-doped calcium silicate scaffolds promote osteochondral regeneration

The development of surface modification techniques has brought about a major paradigm shift in the clinical applications of bone tissue regeneration. Biofabrication strategies enable the creation of scaffolds with specific microstructural environments and biological components. Lithium (Li) has been reported to exhibit anti-inflammatory, osteogenic, and chondrogenic properties by promoting several intracellular signaling pathways. Currently, research focuses on fabricating scaffolds with simultaneous dual bioactivities to enhance osteochondral regeneration. In this study, we modified the surface of calcium silicate (CS) scaffolds with Li using a simple immersion technique and evaluated their capabilities for bone regeneration. The results showed that Li ions could be easily coated onto the surfaces of CS scaffolds without affecting the microstructural properties of CS itself. Furthermore, the modifications did not affect the printing capabilities of the CS, and porous scaffolds could be fabricated via extrusion. Moreover, the presence of Li improved the surface roughness and hydrophilicity, thus leading to enhanced secretion of osteochondral-related regeneration factors, such as alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen II (Col II) proteins. Subsequent in vivo studies, including histological and micro-CT analyses, confirmed that the Li-modified CS scaffolds promoted osteochondral regeneration. The transcriptome analysis suggested that the enhanced osteochondrogenic capabilities of our scaffolds were influenced by paracrine exosomes. We hope this study will inspire further research on osteochondral regeneration.

Correction: Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells

Correction for 'Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells' by Yung-Cheng Chiu et al., J. Mater. Chem. B, 2023, 11, 4666-4676, https://doi.org/10.1039/D3TB00208J.

3D-biofabricated chondrocyte-laden decellularized extracellular matrix-contained gelatin methacrylate auxetic scaffolds under cyclic tensile stimulation for cartilage regeneration

Three-dimensional (3D) hydrogel constructs can mimic features of the extracellular matrix (ECM) and have tailorable physicochemical properties to support and maintain the regeneration of articular cartilage. Various studies have shown that mechanical cues affect the cellular microenvironment and thereby influence cellular behavior. In this study, we fabricated an auxetic scaffold to investigate the effect of 3D tensile stimulation on chondrocyte behavior. Different concentrations of decellularized extracellular matrix (dECM) were mixed with fish gelatin methacrylate (FGelMa) and employed for the preparation of dECM/FGelMa auxetic bio-scaffolds using 3D biofabrication technology. We show that when human chondrocytes (HCs) were incorporated into these scaffolds, their proliferation and the expression of chondrogenesis-related markers increased with dECM content. The function of HC was influenced by cyclic tensile stimulation, as shown by increased production of the chondrogenesis-related markers, collagen II and glycosaminoglycans, with the involvement of the yes-associated protein 1 signaling pathway. The biofabricated auxetic scaffold represents an excellent platform for exploring interactions between cells and their mechanical microenvironment.

Additive manufacturing of barium-doped calcium silicate/poly-ε-caprolactone scaffolds to activate CaSR and AKT signalling and osteogenic differentiation of mesenchymal stem cells

3D-printed scaffolds are suitable for patient-specific implant preparation for bone regeneration in large-scale critical bone defects. In addition, these scaffolds should have mechanical and biological properties similar to those of natural bone tissue. In this study, 3D-printed barium-doped calcium silicate (BaCS)/poly-ε-caprolactone (PCL) composite scaffolds were fabricated as an alternative strategy for bone tissue engineering to achieve appropriate physicochemical characteristics and stimulate osteogenesis. Scaffolds containing 10% Ba (Ba10) showed optimal mechanical properties, preventing premature scaffold degradation during immersion while enabling ion release in a sustained manner to achieve the desired therapeutic goals. In addition, Wharton's jelly mesenchymal stem cells (WJMSCs) were used to assess biocompatibility and osteogenic differentiation behaviour. WJMSCs were cultured on the scaffold and permeabilised via ICP to analyse the presence of Si and Ba ions in the medium and cell lysates, suggesting that the ions released by the scaffold could effectively enter the cells. The protein expression of CaSR, PI3K, Akt, and JNK confirmed that CaSR could activate cells cultured in Ba10, thereby affecting the subsequent PI3k/Akt and JNK pathways and further promoting osteogenic differentiation. The in vivo performance of the proposed scaffolds was assessed using micro-CT and histological slices, which revealed that the BaCS scaffolds could further enhance bone regeneration, compared with bare scaffolds. These results suggest the potential use of 3D-printed BaCS/PCL scaffolds as next-generation substitutes for bone regeneration.

Highly Mimetic Ex Vivo Lung-Cancer Spheroid-Based Physiological Model for Clinical Precision Therapeutics

Lung cancer remains a major health problem despite the considerable research into prevention and treatment methods. Through a deeper understanding of tumors, patient-specific ex vivo spheroid models with high specificity can be used to accurately investigate the cause, metastasis, and treatment strategies for lung cancer. Biofabricate lung tumors are presented, consisting of patient-derived tumor spheroids, endothelial cells, and lung decellularized extracellular matrix, which maintain a radial oxygen gradient, as well as biophysicochemical behaviors of the native tumors for precision medicine. It is also demonstrated that the developed lung-cancer spheroid model reproduces patient responses to chemotherapeutics and targeted therapy in a co-clinical trial, with 85% accuracy, 86.7% sensitivity, and 80% specificity. RNA sequencing analysis validates that the gene expression in the spheroids replicates that in the patient's primary tumor. This model can be used as an ex vivo predictive model for personalized cancer therapy and to improve the quality of clinical care.

Additive manufacturing of Schwann cell-laden collagen/alginate nerve guidance conduits by freeform reversible embedding regulate neurogenesis via exosomes secretion towards peripheral nerve regeneration

Peripheral nerve injury is a common clinical problem that could be debilitating to one's quality of life. The complex nerve guidance conduits (NGCs) with cells in order to improve nerve regeneration. Therefore, we used freeform reversible embedding of suspended hydrogels to fabricate Schwann cells (SCs)-laden collagen/alginate (Col/Alg) NGCs. First, we evaluated Col influence on the characteristics of NGCs. After which, Wharton's jelly mesenchymal stem cells (WJMSC) are seeded onto the inner channel of NGCs and evaluated neural regeneration behaviors. Results indicated the SCs-laden NGCs with 2.5 % Col found the highest proliferation and secretion of neurotrophic protein. Furthermore, co-culture of SCs promoted differentiation of WJMSC as seen from the increased neurogenic-related protein in NGCs. To determine the molecular mechanism between SCs and WJMSC, we demonstrated the neurotrophic factors secreted by SCs act on tropomyosin receptor kinase A (TrkA) receptors of WJMSC to promote nerve regeneration. In addition, our study demonstrated SCs-derived exosomes had a critical role in regulating neural differentiation of WJMSC. Taken together, this study demonstrates the fabrication of SCs-laden Col/Alg NGCs for nerve regeneration and understanding regarding the synergistic regenerative mechanisms of different cells could bring us a step closer for clinical treatment of large nerve defects.

Effect of mussel-inspired polydopamine on the reinforced properties of 3D printed β-tricalcium phosphate/polycaprolactone scaffolds for bone regeneration

Bioceramic/polymer scaffolds have been considered as potential grafts used for facilitating bone healing. Unfortunately, the poor interfacial interaction between polymer matrices and bioceramic fillers limited their use in practical medicine. Thus, a facile strategy for reinforcing the three-dimensional printed β-tricalcium phosphate/polycaprolactone scaffolds through employing polydopamine modified-ceramics as fillers. The effects of the dopamine precursor on the compressive strength, degradability, cell proliferation, osteogenic differentiation, and in vivo osteogenicity were measured. The results indicated that the concentration of dopamine could remarkably affect the thickness and density of the polydopamine layer on fillers, further varying the compressive strength (1.23-fold to 1.64-fold), degradability, and osteogenicity of the scaffolds. More importantly, the presence of polydopamine in the three-dimensional printed composite scaffolds not only facilitated the proliferation, alkaline phosphatase activity and mineralization of mesenchymal stem cells, but also stimulated the formation of neo-bone tissue in femur defects. Taking together, the proposed scaffolds might serve as a candidate for bone regeneration.

The 3D printed conductive grooved topography hydrogel combined with electrical stimulation for synergistically enhancing wound healing of dermal fibroblast cells

Patients with extensive cutaneous damage resulting from poor wound healing often have other comorbidities such as diabetes that may lead to impaired skin functions and scar formation. Many recent studies have shown that the application of electrical stimulation (ES) to cutaneous lesions significantly improves skin regeneration via activation of AKT intracellular signaling cascades and secretion of regeneration-related growth factors. In this study, we fabricated varying concentrations of gelatin-methacrylate (GelMa) hydrogels with poly(3,4-ethylenedioxythiophene) (PEDOT): polystyrene sulfonate (PSS), which is a conductive material commonly used in tissue engineering due to its efficiency among conductive thermo-elastic materials. The results showed successful modification of PEDOT:PSS with GelMa while retaining the original structural characteristics of the GelMa hydrogels. In addition, the incorporation of PEDOT:PSS increased the interactions between both the materials, thus leading to enhanced mechanical strength, improved swelling ratio, and decreased hydrophilicity of the scaffolds. Our GelMa/PEDOT:PSS scaffolds were designed to have micro-grooves on the surfaces of the scaffolds for the purpose of directional guiding. In addition, our scaffolds were shown to have excellent electrical conductivity, thus leading to enhanced cellular proliferation and directional migration and orientation of human dermal fibroblasts. In vivo studies revealed that the GelMa/PEDOT:PSS scaffolds with electrical stimulation were able to induce full skin thickness regeneration, as seen from the various stainings. These results indicate the potential of GelMa/PEDOT:PSS as an electro-conductive biomaterial for future skin regeneration applications.

Combined Effects of Polydopamine-Assisted Copper Immobilization on 3D-Printed Porous Ti6Al4V Scaffold for Angiogenic and Osteogenic Bone Regeneration

Numerous studies have demonstrated that biological compounds and trace elements such as dopamine (DA) and copper ions (Cu) could be modified onto the surfaces of scaffolds using a one-step immersion process which is simple, inexpensive and, most importantly, non-cytotoxic. The development and emergence of 3D printing technologies such as selective laser melting (SLM) have also made it possible for us to fabricate bone scaffolds with precise structural designs using metallic compounds. In this study, we fabricated porous titanium scaffolds (Ti) using SLM and modified the surface of Ti with polydopamine (PDA) and Cu. There are currently no other reported studies with such a combination for osteogenic and angiogenic-related applications. Results showed that such modifications did not affect general appearances and microstructural characteristics of the porous Ti scaffolds. This one-step immersion modification allowed us to modify the surfaces of Ti with different concentrations of Cu ions, thus allowing us to fabricate individualized scaffolds for different clinical scenarios. The modification improved the hydrophilicity and surface roughness of the scaffolds, which in turn led to promote cell behaviors of Wharton’s jelly mesenchymal stem cells. Ti itself has high mechanical strength, therefore making it suitable for surgical handling and clinical applications. Furthermore, the scaffolds were able to release ions in a sustained manner which led to an upregulation of osteogenic-related proteins (bone alkaline phosphatase, bone sialoprotein and osteocalcin) and angiogenic-related proteins (vascular endothelial growth factor and angiopoietin-1). By combining additive manufacturing, Ti6Al4V scaffolds, surface modification and Cu ions, the novel hybrid 3D-printed porous scaffold could be fabricated with ease and specifically benefited future bone regeneration in the clinic.

The Synergistic Effect of Cyclic Tensile Force and Periodontal Ligament Cell-Laden Calcium Silicate/Gelatin Methacrylate Auxetic Hydrogel Scaffolds for Bone Regeneration

The development of 3D printing technologies has allowed us to fabricate complex novel scaffolds for bone regeneration. In this study, we reported the incorporation of different concentrations of calcium silicate (CS) powder into fish gelatin methacrylate (FGelMa) for the fabrication of CS/FGelMa auxetic bio-scaffolds using 3D printing technology. Our results showed that CS could be successfully incorporated into FGelMa without influencing the original structural components of FGelMa. Furthermore, it conveyed that CS modifications both the mechanical properties and degradation rates of the scaffolds were improved in accordance with the concentrations of CS upon modifications of CS. In addition, the presence of CS enhanced the adhesion and proliferation of human periodontal ligament cells (hPDLs) cultured in the scaffold. Further osteogenic evaluation also confirmed that CS was able to enhance the osteogenic capabilities via activation of downstream intracellular factors such as pFAK/FAK and pERK/ERK. More interestingly, it was noted that the application of extrinsic biomechanical stimulation to the auxetic scaffolds further enhanced the proliferation and differentiation of hPDLs cells and secretion of osteogenic-related markers when compared to CS/FGelMa hydrogels without tensile stimulation. This prompted us to explore the related mechanism behind this interesting phenomenon. Subsequent studies showed that biomechanical stimulation works via YAP, which is a biomechanical cue. Taken together, our results showed that novel auxetic scaffolds could be fabricated by combining different aspects of science and technology, in order to improve the future chances of clinical applications for bone regeneration.

Posterior-Stabilized Antibiotic Cement Articulating Spacer With Endoskeleton-Reinforced Cam Reduces Rate of Post-Cam Mechanical Complications in Prosthetic Knee Infection: A Preliminary Study

BACKGROUND

Posterior-stabilized antibiotic cement articulating spacers (PS spacers) reduce spacer mechanical complications in prosthetic knee infections (PKIs); however, joint dislocation after femoral cam fracture has been reported. We hypothesized that the rate of post-cam mechanical complications is lower in PS spacers with an endoskeleton-reinforced cam.

METHOD

A retrospective study of PKIs using PS spacers with or without a Kirschner wire-reinforced cam (K-PS or nK-PS spacers, respectively) was conducted between 2015 and 2019. The rates of post-cam mechanical complications and reoperation, as well as risk factors for post or cam failure, were analyzed.

RESULTS

The cohort included 118 nK-PS and 49 K-PS spacers. All patients were followed up for 2 years. The rate of joint subluxation/dislocation after femoral cam fracture was lower in K-PS (0%) than in nK-PS spacers (17.8%; P = .002). The reoperation rate for spacer mechanical complications was lower in K-PS (0%) than in nK-PS spacers (11.9%; P = .008). The identified risk factors for femoral cam fractures were body mass index ≥25 kg/m², femoral spacer size ≤2, and surgical volume ≤12 resection arthroplasties per year.

CONCLUSION

This preliminary study highlights that K-PS spacers have a lower rate of post-cam mechanical complications than nK-PS spacers. We recommend the use of PS spacers with endoskeleton-reinforced cam when treating PKIs performed by surgeons with lower surgical volumes, especially in patients with higher body mass index and smaller femoral spacer sizes.

Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost's mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations.

The effects of a 3D-printed magnesium-/strontium-doped calcium silicate scaffold on regulation of bone regeneration via dual-stimulation of the AKT and WNT signaling pathways

Numerous studies have demonstrated that calcium silicate (CS) can be doped with various trace metal elements such as strontium (Sr) or magnesium (Mg). These studies have confirmed that such modifications promote bone regeneration. However, the development and emergence of 3D printing have further made it possible to fabricate bone grafts with precise structural designs using multi-bioceramics so as to better suit specific clinical requirements. We fabricated scaffolds using Mg-doped CS as the outer layer with Sr-doped CS in the center. In addition, PCL was used to improve printability of the scaffolds. This enhanced Mg and Sr architecture prevented premature degradation of the scaffolds during immersion while enabling the release of ions in a sustained manner in order to achieve the desired therapeutic goals. Even the capabilities of stem cells were shown to be enhanced when cultured on these scaffolds. Furthermore, the hybrid scaffolds were found to up-regulate the expression of bone-related proteins such as factors leading to differentiation-inducing pathways, including PI3K/Akt, Wnt, and TRPM7. The in vivo performance of the proposed scaffolds was assessed using micro-CT. The histological results revealed that the hybrid scaffolds were able to further enhance bone regeneration as compared to uni-bioceramics. By combining 3D printing, multi-ceramics, and trace metal elements, a novel hybrid scaffold could be fabricated with ease and specifically suited to future bone tissue engineering applications.

Approximate Optimization Study of Light Curing Waterborne Polyurethane Materials for the Construction of 3D Printed Cytocompatible Cartilage Scaffolds

Articular cartilage, which is a white transparent tissue with 1–2 mm thickness, is located in the interface between the two hard bones. The main functions of articular cartilage are stress transmission, absorption, and friction reduction. The cartilage cannot be repaired and regenerated once it has been damaged, and it needs to be replaced by artificial joints. Many approaches, such as artificial joint replacement, hyaluronic acid injection, microfracture surgery and cartilage tissue engineering have been applied in clinical treatment. Basically, some of these approaches are foreign material implantation for joint replacement to reach the goal of pain reduction and mechanism support. This study demonstrated another frontier in the research of cartilage reconstruction by applying regeneration medicine additive manufacturing (3D Printing) and stem cell technology. Light curing materials have been modified and tested to be printable and cytocompatible for stem cells in this research. Design of experiments (DOE) is adapted in this investigation to search for the optimal manufacturing parameter for biocompatible scaffold fabrication and stem cell attachment and growth. Based on the results, an optimal working process of biocompatible and printable scaffolds for cartilage regeneration is reported. We expect this study will facilitate the development of cartilage tissue engineering.

Cruciate-Retaining vs Posterior-Stabilized Antibiotic Cement Articulating Spacers for Two-Stage Revision of Prosthetic Knee Infection: A Retrospective Cohort Study

BACKGROUND

Antibiotic cement articulating spacers are recommended during 2-stage revision for prosthetic knee infection because of increased range of motion (ROM) and improved function; however, spacer mechanical complications have been reported. We aimed to determine the association between different constraints of articulating spacers and the rate of complications and infection eradication, functional outcomes, and ROM.

METHODS

A retrospective study of prosthetic knee infection using cruciate-retaining (CR) or posterior-stabilized (PS) spacers was conducted between 2011 and 2018. The rate of spacer mechanical complications, infection eradication after reimplantation and reoperation, Hospital of Special Surgery (HSS) knee score, and ROM during the interim stage were analyzed. All patients were regularly followed up for 2 years.

RESULTS

One hundred forty-one patients were included, with 66 CR and 75 PS spacers. Overall mechanical complication rate was lower in PS (9.3%) than in CR spacers (45.5%) (P < .001), especially in joint dislocation (1.3% vs 30.3%, respectively, P < .001). Overall reoperation rate was lower in PS (16.0%) than in CR spacers (36.4%) (P < .001), especially for mechanical complications (1.3% vs 24.2%, respectively, P < .001). HSS knee score was higher in PS (72.3) than in CR spacers (63.8) (P < .001). ROM was greater in PS (90.3°) than in CR spacers (80.6°) (P = .005), especially at maximum flexion (102.4° vs 89.6°, respectively, P = .003). Infection eradication was comparable between the spacers.

CONCLUSION

Both spacers can control infection; however, PS spacers had a lower rate of mechanical complications and reoperation, better HSS knee scores, and greater ROM than CR spacers.

Synergies of Human Umbilical Vein Endothelial Cell-Laden Calcium Silicate-Activated Gelatin Methacrylate for Accelerating 3D Human Dental Pulp Stem Cell Differentiation for Endodontic Regeneration

According to the Centers for Disease Control and Prevention, tooth caries is a common problem affecting 9 out of every 10 adults worldwide. Dentin regeneration has since become one of the pressing issues in dentistry with tissue engineering emerging as a potential solution for enhancing dentin regeneration. In this study, we fabricated cell blocks with human dental pulp stem cells (hDPSCs)-laden alginate/fish gelatin hydrogels (Alg/FGel) at the center of the cell block and human umbilical vascular endothelial cells (HUVEC)-laden Si ion-infused fish gelatin methacrylate (FGelMa) at the periphery of the cell block. ¹H NMR and FTIR results showed the successful fabrication of Alg/FGel and FGelMa. In addition, Si ions in the FGelMa were noted to be bonded via covalent bonds and the increased number of covalent bonds led to an increase in mechanical properties and improved degradation of FGelMa. The Si-containing FGelMa was able to release Si ions, which subsequently significantly not only enhanced the expressions of angiogenic-related protein, but also secreted some cytokines to regulate odontogenesis. Further immunofluorescence results indicated that the cell blocks allowed interactions between the HUVEC and hDPSCs, and taken together, were able to enhance odontogenic-related markers' expression, such as alkaline phosphatase (ALP), dentin matrix phosphoprotein-1 (DMP-1), and osteocalcin (OC). Subsequent Alizarin Red S stain confirmed the benefits of our cell block and demonstrated that such a novel combination and modification of biomaterials can serve as a platform for future clinical applications and use in dentin regeneration.

3D-Printed Ginsenoside Rb1-Loaded Mesoporous Calcium Silicate/Calcium Sulfate Scaffolds for Inflammation Inhibition and Bone Regeneration

Bone defects are commonly found in the elderly and athletic population due to systemic diseases such as osteoporosis and trauma. Bone scaffolds have since been developed to enhance bone regeneration by acting as a biological extracellular scaffold for cells. The main advantage of a bone scaffold lies in its ability to provide various degrees of structural support and growth factors for cellular activities. Therefore, we designed a 3D porous scaffold that can not only provide sufficient mechanical properties but also carry drugs and promote cell viability. Ginsenoside Rb1 (GR) is an extract from panax ginseng, which has been used for bone regeneration and repair since ancient Chinese history. In this study, we fabricated scaffolds using various concentrations of GR with mesoporous calcium silicate/calcium sulfate (MSCS) and investigated the scaffold’s physical and chemical characteristic properties. PrestoBlue, F-actin staining, and ELISA were used to demonstrate the effect of the GR-contained MSCS scaffold on cell proliferation, morphology, and expression of the specific osteogenic-related protein of human dental pulp stem cells (hDPSCs). According to our data, hDPSCs cultivated in GR-contained MSCS scaffold had preferable abilities of proliferation and higher expression of the osteogenic-related protein and could effectively inhibit inflammation. Finally, in vivo performance was assessed using histological results that revealed the GR-contained MSCS scaffolds were able to further achieve more effective hard tissue regeneration than has been the case in the past. Taken together, this study demonstrated that a GR-containing MSCS 3D scaffold could be used as a potential alternative for future bone tissue engineering studies and has good potential for clinical use.

Digital Light Processing Bioprinted Human Chondrocyte-Laden Poly (γ-Glutamic Acid)/Hyaluronic Acid Bio-Ink towards Cartilage Tissue Engineering

Cartilage injury is the main cause of disability in the United States, and it has been projected that cartilage injury caused by osteoarthritis will affect 30% of the entire United States population by the year 2030. In this study, we modified hyaluronic acid (HA) with γ-poly(glutamic) acid (γ-PGA), both of which are common biomaterials used in cartilage engineering, in an attempt to evaluate them for their potential in promoting cartilage regeneration. As seen from the results, γ-PGA-GMA and HA, with glycidyl methacrylate (GMA) as the photo-crosslinker, could be successfully fabricated while retaining the structural characteristics of γ-PGA and HA. In addition, the storage moduli and loss moduli of the hydrogels were consistent throughout the curing durations. However, it was noted that the modification enhanced the mechanical properties, the swelling equilibrium rate, and cellular proliferation, and significantly improved secretion of cartilage regeneration-related proteins such as glycosaminoglycan (GAG) and type II collagen (Col II). The cartilage tissue proof with Alcian blue further demonstrated that the modification of γ-PGA with HA exhibited suitability for cartilage tissue regeneration and displayed potential for future cartilage tissue engineering applications. This study built on the previous works involving HA and further showed that there are unlimited ways to modify various biomaterials in order to further bring cartilage tissue engineering to the next level.

Calcium Silicate-Activated Gelatin Methacrylate Hydrogel for Accelerating Human Dermal Fibroblast Proliferation and Differentiation

Wound healing is a complex process that requires specific interactions between multiple cells such as fibroblasts, mesenchymal, endothelial, and neural stem cells. Recent studies have shown that calcium silicate (CS)-based biomaterials can enhance the secretion of growth factors from fibroblasts, which further increased wound healing and skin regeneration. In addition, gelatin methacrylate (GelMa) is a compatible biomaterial that is commonly used in tissue engineering. However, it has low mechanical properties, thus restricting its fullest potential for clinical applications. In this study, we infused Si ions into GelMa hydrogel and assessed for its feasibility for skin regeneration applications by observing for its influences on human dermal fibroblasts (hDF). Initial studies showed that Si could be successfully incorporated into GelMa, and printability was not affected. The degradability of Si-GelMa was approximately 20% slower than GelMa hydrogels, thus allowing for better wound healing and regeneration. Furthermore, Si-GelMa enhanced cellular adhesion and proliferation, therefore leading to the increased secretion of collagen I other important extracellular matrix (ECM) remodeling-related proteins including Ki67, MMP9, and decorin. This study showed that the Si-GelMa hydrogels were able to enhance the activity of hDF due to the gradual release of Si ions, thus making it a potential candidate for future skin regeneration clinical applications.

The synergistic effects of Xu Duan combined Sr-contained calcium silicate/poly-ε-caprolactone scaffolds for the promotion of osteogenesis marker expression and the induction of bone regeneration in osteoporosis

Osteoporosis and its related problems such as fractures are gradually becoming common due to an aging population. Current methods to treat osteoporosis include medical and surgical options such as bone implants. Recent developments in 3D printing and materials science technologies has allowed us to fabricate individualized scaffolds with desired properties. In this study, we mixed Xu Duan into strontium‑calcium silicate powder at 5% (XD5) and 10% (XD10) and fabricated 3D scaffolds with polycaprolactone. All scaffolds were assessed for its physical, mechanical, and biological properties to evaluated for its feasibility for bone tissue engineering in the osteoporosis model. Our results showed that such a scaffold could be fabricated using extrusion-based printing techniques and that addition of XD did not alter original structural properties of the SrCS. Furthermore, the XD5 and XD10 scaffolds were found to be non-toxic to cells and cells cultured on the scaffolds had significantly higher proliferation and secreted increased osteogenic-related proteins in in vitro studies as compared to the XD0 groups. Remarkably, the XD10 scaffolds could be used as substitutes for the critical-sized bone defect (7.0 mm diameter and 8.0 mm depth) in the osteoporotic rabbit model. The XD10 scaffolds can enhance bone ingrowth and accelerate new bone regeneration even in complex osteoporotic pathological environments. These results showed that such a Chinese medicine-contained scaffold had potential in osteoporosis bone tissue regeneration and could be considered as a promising tool for future clinical used applications.

Effects of Gelatin Methacrylate Bio-ink Concentration on Mechano-Physical Properties and Human Dermal Fibroblast Behavior

Gelatin-methacryloyl (GelMa) is a very versatile biomaterial widely used in various biomedical applications. The addition of methacryloyl makes it possible to have hydrogels with varying mechanical properties due to its photocuring characteristics. In addition, gelatin is obtained and derived from natural material; thus, it retains various cell-friendly motifs, such as arginine-glycine-aspartic acid, which then provides implanted cells with a friendly environment for proliferation and differentiation. In this study, we fabricated human dermal fibroblast cell (hDF)-laden photocurable GelMa hydrogels with varying physical properties (5%, 10%, and 15%) and assessed them for cellular responses and behavior, including cell spreading, proliferation, and the degree of extracellular matrix remodeling. Under similar photocuring conditions, lower concentrations of GelMa hydrogels had lower mechanical properties than higher concentrations. Furthermore, other properties, such as swelling and degradation, were compared in this study. In addition, our findings revealed that there were increased remodeling and proliferation markers in the 5% GelMa group, which had lower mechanical properties. However, it was important to note that cellular viabilities were not affected by the stiffness of the hydrogels. With this result in mind, we attempted to fabricate 5-15% GelMa scaffolds (20 × 20 × 3 mm3) to assess their feasibility for use in skin regeneration applications. The results showed that both 10% and 15% GelMa scaffolds could be fabricated easily at room temperature by adjusting several parameters, such as printing speed and extrusion pressure. However, since the sol-gel temperature of 5% GelMa was noted to be lower than its counterparts, 5% GelMa scaffolds had to be printed at low temperatures. In conclusion, GelMa once again was shown to be an ideal biomaterial for various tissue engineering applications due to its versatile mechanical and biological properties. This study showed the feasibility of GelMa in skin tissue engineering and its potential as an alternative for skin transplants.

Enzyme-Cross-linked Gelatin Hydrogel Enriched with an Articular Cartilage Extracellular Matrix and Human Adipose-Derived Stem Cells for Hyaline Cartilage Regeneration of Rabbits

Hyaline cartilage regeneration remains clinically challenging. In this study, microbial transglutaminase was used to cross-link gelatin. The articular cartilage extracellular matrix (cECM), mainly comprising collagen type II and glycosaminoglycans (GAGs), which can support chondrogenesis, was enclosed in this enzyme-catalyzed hydrogel. After human adipose-derived stem cells (hASCs) were encapsulated in the hydrogel enriched with the cECM, the results demonstrated that the enzymatic cross-linking reaction is of low cytotoxicity. Moreover, the stem cells showed great proliferation and chondrogenic differentiation potential in the hydrogel. Most importantly, we assessed the therapeutic effects of applying a hydrogel enriched with the cECM and hASCs to repair a full-thickness osteochondral defect. At 8 weeks after surgery, the GCC group (hydrogel encapsulating cells and the cECM) exhibited a smooth articular surface with transparent new hyaline-like tissue macroscopically. According to histological analysis, inflammatory responses were hardly observed, and sound chondrocytes were aligned in the newly formed chondral layer. In addition, the GCC group exhibited significant improvement in the GAG content between weeks 4 and 8. In summary, the implantation of a gelatin hydrogel enriched with the cECM and hASCs could facilitate the hyaline cartilage regeneration significantly in rabbit knee joint models.

Caffeic Acid-coated Nanolayer on Mineral Trioxide Aggregate Potentiates the Host Immune Responses, Angiogenesis, and Odontogenesis

INTRODUCTION

The aim of this study was to investigate whether mineral trioxide aggregate (MTA) can be modified with caffeic acid (CA) to form caffeic acid/mineral trioxide aggregate (CAMTA) cement and to evaluate its physicochemical and biological properties as well as its capability in immune suppression and angiogenesis.

METHODS

MTA was immersed in trishydroxymethyl aminomethane buffer with CA to allow coating onto MTA powders. X-ray diffractometry and tensile stress-strain tests were conducted to assess for physical characteristics of CAMTA and to evaluate for successful modification of MTA. Then, the CAMTA cement was immersed in simulated body fluid to evaluate its hydroxyapatite formation capabilities and Si release profiles. In addition, RAW 264.7 cells and human dental pulp stem cells were used to evaluate CAMTA's immunosuppressive capabilities and cell responses, respectively. hDPSCs were also used to assess CAMTA's angiogenic capabilities.

RESULTS

The X-ray diffractometry results showed that CA can be successfully coated onto MTA without disrupting or losing MTA's original structural properties, thus allowing us to retain the initial advantages of MTA. CAMTA was shown to have higher mechanical properties compared with MTA and had rougher pitted surfaces, which were hypothesized to lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. In addition, it was found that CAMTA was able to enhance hydroxyapatite formation and immunosuppressive capabilities compared with MTA.

CONCLUSIONS

CAMTA cements were found to have improved physicochemical and biological characteristics compared with their counterpart. In addition, CAMTA cements had enhanced odontogenic, angiogenic, and immunosuppressive properties compared with MTA. All of the results of this study proved that CAMTA cements could be a biomaterial for future clinical applications and tissue engineering use.

Review of Polymeric Materials in 4D Printing Biomedical Applications

The purpose of 4D printing is to embed a product design into a deformable smart material using a traditional 3D printer. The 3D printed object can be assembled or transformed into intended designs by applying certain conditions or forms of stimulation such as temperature, pressure, humidity, pH, wind, or light. Simply put, 4D printing is a continuum of 3D printing technology that is now able to print objects which change over time. In previous studies, many smart materials were shown to have 4D printing characteristics. In this paper, we specifically review the current application, respective activation methods, characteristics, and future prospects of various polymeric materials in 4D printing, which are expected to contribute to the development of 4D printing polymeric materials and technology.

Additive Manufacturing of Nerve Decellularized Extracellular Matrix-Contained Polyurethane Conduits for Peripheral Nerve Regeneration

The nervous system is the part of our body that plays critical roles in the coordination of actions and sensory information as well as communication between different body parts through electrical signal transmissions. Current studies have shown that patients are likely to experience a functional loss if they have to go through a nerve repair for >15 mm lesion. The ideal treatment methodology is autologous nerve transplant, but numerous problems lie in this treatment method, such as lack of harvesting sites. Therefore, researchers are attempting to fabricate alternatives for nerve regeneration, and nerve conduit is one of the potential alternatives for nerve regeneration. In this study, we fabricated polyurethane/polydopamine/extracellular matrix (PU/PDA/ECM) nerve conduits using digital light processing (DLP) technology and assessed for its physical properties, biodegradability, cytocompatibility, neural related growth factor, and proteins secretion and expression and its potential in allowing cellular adhesion and proliferation. It was reported that PU/PDA/ECM nerve conduits were more hydrophilic and allowed enhanced cellular adhesion, proliferation, expression, and secretion of neural-related proteins (collagen I and laminin) and also enhanced expression of neurogenic proteins, such as nestin and microtubule-associated protein 2 (MAP2). In addition, PU/PDA/ECM nerve conduits were reported to be non-cytotoxic, had sustained biodegradability, and had similar physical characteristics as PU conduits. Therefore, we believed that PU/PDA/ECM nerve conduits could be a potential candidate for future nerve-related research or clinical applications.

The mussel-inspired assisted apatite mineralized on PolyJet material for artificial bone scaffold

With the development of three-dimensional (3D) printing, many commercial 3D printing materials have been applied in the fields of biomedicine and medical. MED610 is a clear, biocompatible PolyJet material that is medically certified for bodily contact. In this study, the polydopamine (PDA)/hydroxyapatite (HA) coating was added to the printed MED610 objects to evaluate its physical properties, cell proliferation, cell morphology, and alkaline phosphatase expression level. The results show that the PDA/HA coating helps printed objects to enhance the hardness, biocompatibility, and osteogenic differentiation potential. We expect that PDA/HA coatings contribute to the applicability of MED610 in biomedical and medical applications.

Application of piezoelectric cells printing on three-dimensional porous bioceramic scaffold for bone regeneration

In recent years, the additive manufacture was popularly used in tissue engineering, as the various technologies for this field of research can be used. The most common method is extrusion, which is commonly used in many bioprinting applications, such as skin. In this study, we combined the two printing techniques; first, we use the extrusion technology to form the ceramic scaffold. Then, the stem cells were printed directly on the surface of the ceramic scaffold through a piezoelectric nozzle. We also evaluated the effects of polydopamine (PDA)-coated ceramic scaffolds for cell attachment after printing on the surface of the scaffold. In addition, we used fluorescein isothiocyanate to simulate the cell adhered on the scaffold surface after ejected by a piezoelectric nozzle. Finally, the attachment, growth, and differentiation behaviors of stem cell after printing on calcium silicate/polycaprolactone (CS/PCL) and PDACS/PCL surfaces were also evaluated. The PDACS/PCL scaffold is more hydrophilic than the original CS/PCL scaffold that provided for better cellular adhesion and proliferation. Moreover, the cell printing technology using the piezoelectric nozzle, the different cells can be accurately printed on the surface of the scaffold that provided and analyzed more information of the interaction between different cells on the material. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

Application of piezoelectric cells printing on three-dimensional porous bioceramic scaffold for bone regeneration

In recent years, the additive manufacture was popularly used in tissue engineering, as the various technologies for this field of research can be used. The most common method is extrusion, which is commonly used in many bioprinting applications, such as skin. In this study, we combined the two printing techniques; first, we use the extrusion technology to form the ceramic scaffold. Then, the stem cells were printed directly on the surface of the ceramic scaffold through a piezoelectric nozzle. We also evaluated the effects of polydopamine (PDA)-coated ceramic scaffolds for cell attachment after printing on the surface of the scaffold. In addition, we used fluorescein isothiocyanate to simulate the cell adhered on the scaffold surface after ejected by a piezoelectric nozzle. Finally, the attachment, growth, and differentiation behaviors of stem cell after printing on calcium silicate/polycaprolactone (CS/PCL) and PDACS/PCL surfaces were also evaluated. The PDACS/PCL scaffold is more hydrophilic than the original CS/PCL scaffold that provided for better cellular adhesion and proliferation. Moreover, the cell printing technology using the piezoelectric nozzle, the different cells can be accurately printed on the surface of the scaffold that provided and analyzed more information of the interaction between different cells on the material. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

The synergistic effects of graphene-contained 3D-printed calcium silicate/poly-ε-caprolactone scaffolds promote FGFR-induced osteogenic/angiogenic differentiation of mesenchymal stem cells

Graphene-contained calcium silicate (CS)/polycaprolactone (PCL) scaffold (GCP) provides an alternative solution that can bring several bone formation properties, such as osteoinductive. This study finds out the optimal percentage of graphene additive to calcium silicate and polycaprolactone mixture for excellent in vitro and in vivo bone-regeneration ability, in addition, this scaffold could fabricate by 3D printing technology and demonstrates distinct mechanical, degradation, and biological behavior. With controlled structure and porosity by 3D printing, osteogenesis and proliferation capabilities of Wharton's Jelly derived mesenchymal stem cells (WJMSCs) were significantly enhanced when cultured on 3D printed GCP scaffolds. In this study, it was also discovered that fibroblast growth factor receptor (FGFR) plays an active role in modulating differentiation behavior of WJMSCs cultured on GCP scaffolds. The validation has been proved by analyzed the decreased cell proliferation, osteogenic-related protein (ALP and OC), and angiogenic-related protein (VEGF and vWF) with FGFR knockdown on all experimental groups. Moreover, this study infers that the GCP scaffold could induce the effects of proliferation, differentiation and related protein expression on WJMSCs through FGFR pathway. In summary, this research indicated the 3D-printed GCP scaffolds own the dual bioactivities to reach the osteogenesis and vascularization for bone regeneration.

Development of mussel-inspired 3D-printed poly (lactic acid) scaffold grafted with bone morphogenetic protein-2 for stimulating osteogenesis

3D printing is a versatile technique widely applied in tissue engineering due to its ability to manufacture large quantities of scaffolds or constructs with various desired architectures. In this study, we demonstrated that poly (lactic acid) (PLA) scaffolds fabricated via fused deposition not only retained the original interconnected microporous architectures, the scaffolds also exhibited lower lactic acid dissolution as compared to the freeze-PLA scaffold. The 3D-printed scaffolds were then grafted with human bone morphogenetic protein-2 (BMP-2) via the actions of polydopamine (PDA) coatings. The loading and release rate of BMP-2 were monitored for a period of 35 days. Cellular behaviors and osteogenic activities of co-cultured human mesenchymal stem cells (hMSCs) were assessed to determine for efficacies of scaffolds. In addition, we demonstrated that our fabricated scaffolds were homogenously coated with PDA and well grafted with BMP-2 (219.1 ± 20.4 ng) when treated with 250 ng/mL of BMP-2 and 741.4 ± 127.3 ng when treated with 1000 ng/mL of BMP-2. This grafting enables BMP-2 to be released in a sustained profile. From the osteogenic assay, it was shown that the ALP activity and osteocalcin of hMSCs cultured on BMP-2/PDA/PLA were significantly higher when compared with PLA and PDA/PLA scaffolds. The methodology of PDA coating employed in this study can be used as a simple model to immobilize multiple growth factors onto different 3D-printed scaffold substrates. Therefore, there is potential for generation of scaffolds with different unique modifications with different capabilities in regulating physiochemical and biological properties for future applications in bone tissue engineering.

Effect of Strontium Substitution on the Physicochemical Properties and Bone Regeneration Potential of 3D Printed Calcium Silicate Scaffolds

In this study, we synthesized strontium-contained calcium silicate (SrCS) powder and fabricated SrCS scaffolds with controlled precise structures using 3D printing techniques. SrCS scaffolds were shown to possess increased mechanical properties as compared to calcium silicate (CS) scaffolds. Our results showed that SrCS scaffolds had uniform interconnected macropores (~500 µm) with a compressive strength 2-times higher than that of CS scaffolds. The biological behaviors of SrCS scaffolds were assessed using the following characteristics: apatite-precipitating ability, cytocompatibility, proliferation, and osteogenic differentiation of human mesenchymal stem cells (MSCs). With CS scaffolds as controls, our results indicated that SrCS scaffolds demonstrated good apatite-forming bioactivity with sustained release of Si and Sr ions. The in vitro tests demonstrated that SrCS scaffolds possessed excellent biocompatibility which in turn stimulated adhesion, proliferation, and differentiation of MSCs. In addition, the SrCS scaffolds were able to enhance MSCs synthesis of osteoprotegerin (OPG) and suppress macrophage colony-stimulating factor (M-CSF) thus disrupting normal bone homeostasis which led to enhanced bone formation over bone resorption. Implanted SrCS scaffolds were able to promote new blood vessel growth and new bone regeneration within 4 weeks after implantation in critical-sized rabbit femur defects. Therefore, it was shown that 3D printed SrCS scaffolds with specific controllable structures can be fabricated and SrCS scaffolds had enhanced mechanical property and osteogenesis behavior which makes it a suitable potential candidate for bone regeneration.

Enhanced Capability of Bone Morphogenetic Protein 2-loaded Mesoporous Calcium Silicate Scaffolds to Induce Odontogenic Differentiation of Human Dental Pulp Cells

INTRODUCTION

Calcium silicate bioceramics have been broadly used as reparative or grafting materials with good bioactivity and biocompatibility in dental application. It has been shown that applying a mesoporous process to calcium silicate gives it great potential as a controlled drug delivery system.

METHODS

The aim of this study was to investigate a novel osteoinductive scaffold by loading bone morphogenetic protein 2 (BMP-2) to mesoporous calcium silicate (MesoCS) and fabricating it as 3-dimensional scaffolds using fused deposition modeling combined with polycaprolactone.

RESULTS

The MesoCS/BMP-2 scaffold showed similar patterns to that of a calcium silicate scaffold in releasing calcium and silicon ions in a simulated body fluid (SBF) immersion test for 7 days, but BMP-2 continued releasing from the MesoCS/BMP-2 scaffold significantly more than the CS scaffold from 48 hours to 7 days. Adhesion and proliferation of human dental pulp cells cultured on a MesoCS/BMP-2 scaffold were also more significant than scaffolds without BMP-2 or mesoporous as well as the results of the test on alkaline phosphatase activity.

CONCLUSIONS

The results support that the novel 3-dimensional-printed MesoCS scaffold performed well as BMP-2 delivery system and would be an ideal odontoinductive biomaterial in regenerative endodontics.

3D-Printed Bioactive Calcium Silicate/Poly-ε-Caprolactone Bioscaffolds Modified with Biomimetic Extracellular Matrices for Bone Regeneration

Currently, clinically available orthopedic implants are extremely biocompatible but they lack specific biological characteristics that allow for further interaction with surrounding tissues. The extracellular matrix (ECM)-coated scaffolds have received considerable interest for bone regeneration due to their ability in upregulating regenerative cellular behaviors. This study delves into the designing and fabrication of three-dimensional (3D)-printed scaffolds that were made out of calcium silicate (CS), polycaprolactone (PCL), and decellularized ECM (dECM) from MG63 cells, generating a promising bone tissue engineering strategy that revolves around the concept of enhancing osteogenesis by creating an osteoinductive microenvironment with osteogenesis-promoting dECM. We cultured MG63 on scaffolds to obtain a dECM-coated CS/PCL scaffold and further studied the biological performance of the dECM hybrid scaffolds. The results indicated that the dECM-coated CS/PCL scaffolds exhibited excellent biocompatibility and effectively enhanced cellular adhesion, proliferation, and differentiation of human Wharton's Jelly mesenchymal stem cells by increasing the expression of osteogenic-related genes. They also presented anti-inflammatory characteristics by showing a decrease in the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1 (IL-1). Histological analysis of in vivo experiments presented excellent bone regenerative capabilities of the dECM-coated scaffold. Overall, our work presented a promising technique for producing bioscaffolds that can augment bone tissue regeneration in numerous aspects.

Improved Bioactivity of 3D Printed Porous Titanium Alloy Scaffold with Chitosan/Magnesium-Calcium Silicate Composite for Orthopaedic Applications

Recently, cases of bone defects have been increasing incrementally. Thus, repair or replacement of bone defects is gradually becoming a huge problem for orthopaedic surgeons. Three-dimensional (3D) scaffolds have since emerged as a potential candidate for bone replacement, of which titanium (Ti) alloys are one of the most promising candidates among the metal alloys due to their low cytotoxicity and mechanical properties. However, bioactivity remains a problem for metal alloys, which can be enhanced using simple immersion techniques to coat bioactive compounds onto the surface of Ti⁻6Al⁻4V scaffolds. In our study, we fabricated magnesium-calcium silicate (Mg⁻CS) and chitosan (CH) compounds onto Ti⁻6Al⁻4V scaffolds. Characterization of these surface-modified scaffolds involved an assessment of physicochemical properties as well as mechanical testing. Adhesion, proliferation, and growth of human Wharton's Jelly mesenchymal stem cells (WJMSCs) were assessed in vitro. In addition, the cell attachment morphology was examined using scanning electron microscopy to assess adhesion qualities. Osteogenic and mineralization assays were conducted to assess osteogenic expression. In conclusion, the Mg⁻CS/CH coated Ti⁻6Al⁻4V scaffolds were able to exhibit and retain pore sizes and their original morphologies and architectures, which significantly affected subsequent hard tissue regeneration. In addition, the surface was shown to be hydrophilic after modification and showed mechanical strength comparable to natural bone. Not only were our modified scaffolds able to match the mechanical properties of natural bone, it was also found that such modifications enhanced cellular behavior such as adhesion, proliferation, and differentiation, which led to enhanced osteogenesis and mineralization downstream. In vivo results indicated that Mg⁻CS/CH coated Ti⁻6Al⁻4V enhances the bone regeneration and ingrowth at the critical size bone defects of rabbits. These results indicated that the proposed Mg⁻CS/CH coated Ti⁻6Al⁻4V scaffolds exhibited a favorable, inducive micro-environment that could serve as a promising modification for future bone tissue engineering scaffolds.

The Physicochemical Properties of Decellularized Extracellular Matrix-Coated 3D Printed Poly(ε-caprolactone) Nerve Conduits for Promoting Schwann Cells Proliferation and Differentiation

Although autologous nerve grafting remains the gold standard treatment for peripheral nerve injuries, alternative methods such as development of nerve guidance conduits have since emerged and evolved to counter the many disadvantages of nerve grafting. However, the efficacy and viability of current nerve conduits remain unclear in clinical trials. Here, we focused on a novel decellularized extracellular matrix (dECM) and polydopamine (PDA)-coated 3D-printed poly(ε-caprolactone) (PCL)-based conduits, whereby the PDA surface modification acts as an attachment platform for further dECM attachment. We demonstrated that dECM/PDA-coated PCL conduits possessed higher mechanical properties when compared to human or animal nerves. Such modifications were proved to affect cell behaviors. Cellular behaviors and neuronal differentiation of Schwann cells were assessed to determine for the efficacies of the conduits. There were some cell-specific neuronal markers, such as Nestin, neuron-specific class III beta-tubulin (TUJ-1), and microtubule-associated protein 2 (MAP2) analyzed by enzyme-linked immunosorbent assay, and Nestin expressions were found to be 0.65-fold up-regulated, while TUJ1 expressions were 2.3-fold up-regulated and MAP2 expressions were 2.5-fold up-regulated when compared to Ctl. The methodology of PDA coating employed in this study can be used as a simple model to immobilize dECM onto PCL conduits, and the results showed that dECM/PDA-coated PCL conduits can as a practical and clinically viable tool for promoting regenerative outcomes in larger peripheral nerve defects.

Effects of bone morphogenic protein-2 loaded on the 3D-printed MesoCS scaffolds

BACKGROUND/PURPOSE

The mesoporous calcium silicate (MesoCS) 3D-printed scaffold show excellent bioactivity and can enhance the bone-like apatite formation. The purpose of this study aims to consider the effects of the different loading methods on the novel grafting materials which composed of bone morphogenetic protein-2 (BMP-2) loaded MesoCS scaffold by employing 3D-printing technique.

METHODS

The MesoCS scaffold were fabricated by fused deposition modeling. In this study, there are two methods of loading BMP-2: (1) the pre-loading (PL) method by mixing MesoCS and BMP-2 as a raw material for a 3D-printer, and (2) the direct-loading (DL) method by soaking the 3D-printed MesoCS scaffold in a BMP-2 solution. The characteristics of MesoCS scaffold were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Their physical properties, biocompatibility, and osteogenic-related ability were also evaluated.

RESULTS

The 3D MesoCS/PCL scaffolds showed excellent biocompatibility and physical properties. After soaking in simulated body fluid, the bone-like apatite layer of the PL and DL groups could be formed. In addition, the DL group released fifty percent more than the PL group at the end of the first day and PL showed a sustained release profile after 2 weeks.

CONCLUSION

The 3D MesoCS/PCL porous scaffolds were successfully fabricated via a 3D printing system and were tested in vitro and were found to show good cellular activity for cell behavior although the PL method was not favorable for clinical application in relation with the preservation of BMP-2. With regards to different growth factor loading methods, this study demonstrated that PL of BMP-2 into MesoCS prior to printing will result in a more sustained drug release pattern as compared to traditional methods of scaffolds directly immersed with BMP-2.

Therapeutic Effects of the Addition of Platelet-Rich Plasma to Bioimplants and Early Rehabilitation Exercise on Articular Cartilage Repair

BACKGROUND

Treating articular cartilage lesions is clinically challenging. However, whether the addition of autologous platelet-rich plasma (PRP) to bioimplants along with early rehabilitation exercise provides therapeutic effects and regenerates the osteochondral defect remains uninvestigated.

HYPOTHESIS

The addition of PRP to a polylactic-co-glycolic acid (PLGA) scaffold along with continuous passive motion (CPM) in osteochondral defects may offer beneficial in situ microenvironment changes to facilitate hyaline cartilage and subchondral bone tissue repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 26 rabbits, 52 critical osteochondral defects were created in bilateral femoral trochlear grooves. The rabbits were allocated to 1 of the following 3 groups: PRP gel (PG group), PRP + PLGA scaffold (PP group), and PRP + PLGA scaffold + CPM (PPC group). At 4 and 12 weeks after surgery, the specimens were assessed by a macroscopic examination, a histological evaluation with immunohistochemical staining, and micro-computed tomography.

RESULTS

The PPC group exhibited the most favorable therapeutic outcomes in terms of hyaline cartilage regeneration. At week 4, the PPC group exhibited significantly higher levels of glycosaminoglycan (GAG) and collagen (COL) II and modest increases in COL I, matrix metalloproteinase-3 (MMP-3), and inflammatory cells with tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6). At week 12, the PPC group had significantly higher tissue repair scores, corresponding to a sound articular cartilage surface and chondrocyte and collagen arrangement. This group demonstrated restored hyaline cartilage and mineralized bone volume per tissue volume, which had an integrating structure in the repair site. However, the PG and PP groups exhibited mainly fibrous tissue and fibrocartilage, corresponding to higher expressions of COL I, TNF-α, IL-6, and MMP-3.

CONCLUSION

PRP with a PLGA graft along with early CPM exercise is promising for the repair of osteochondral defects in rabbit knee joints.

CLINICAL RELEVANCE

This study demonstrates the efficacy of a triad therapy involving the addition of PRP to bioimplants along with early CPM intervention for hyaline cartilage and subchondral regeneration. However, PRP alone (with or without PLGA implants) is limited to osteochondral defect repair without significant regeneration.

Osteogenic and angiogenic potentials of the cell-laden hydrogel/mussel-inspired calcium silicate complex hierarchical porous scaffold fabricated by 3D bioprinting

3D printing has been popularly used in the bone tissue engineering, as many of the biomaterials for this field of study can be prepared for and produced from this additive manufacturing technique. In this study, we strategized a solvent-free processing to fabricate the polydopamine-modified calcium silicate (PDACS)/poly-caprolactone (PCL) scaffold with Wharton's jelly mesenchymal stem cells (WJMSCs) incorporated with human umbilical vein endothelial cells (HUVEC)-laden hydrogel. The PDACS/PCL/hydrogel 3D scaffold yielded a Young's modulus of the 3D scaffolds as high as 75 MPa. In addition, the vascular morphogenesis and cellular behaviors regulated by our hybrid scaffolds were also intricately evaluated. Furthermore, the HUVEC in the bioink exhibited higher levels of angiogenic biomarkers and showed potential for the formation of complex vascular networks. Higher levels of bone formation proteins were also observed in our composites. Such a hybrid of synthetic materials with cell constituents not only enhances osteogenesis but also stimulates vessel network development in angiogenesis, presenting the fact that 3D printing can be further applied in improving bone tissue regeneration in numerous aspects. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

Bioactive calcium silicate/poly-ε-caprolactone composite scaffolds 3D printed under mild conditions for bone tissue engineering

The present study provides a solvent-free processing method for establishing the ideal porous 3-dimension (3D) scaffold filled with different ratios of calcium silicate-based (CS) powder and polycaprolactone (PCL) for 3D bone substitute application. Characterization of hybrid scaffolds developed underwent assessments for physicochemical properties and biodegradation. Adhesion and growth of human Wharton's Jelly mesenchymal stem cells (WJMSCs) on the CS/PCL blended scaffold were investigated in vitro. Cell attachment and morphology were examined by scanning electron microscope (SEM) and confocal microscope observations. Colorimetric assay was tested for assessing cell metabolic activity. In addition, RT-qPCR was also performed for the osteogenic-related and angiogenesis-related gene expression. As a result, the hydrophilicity of the scaffolds was further significantly improved after we additive CS into PCL, as well as the compressive strength up to 5.8 MPa. SEM showed that a great amount of precipitated bone-like apatite formed on the scaffold surface after immersed in the simulated body fluid. The 3D-printed scaffolds were found to enhance cell adhesion, proliferation and differentiation. Additionally, results of osteogenesis and angiogenesis proteins were expressed obviously greater in the response of WJMSCs. These results indicate the CS/PCL composite exhibited a favorable bioactivity and osteoconductive properties that could be served as a promising biomaterial for bone tissue engineering scaffolds.

Biodegradable Bisvinyl Sulfonemethyl-crosslinked Gelatin Conduit Promotes Regeneration after Peripheral Nerve Injury in Adult Rats

In our previous study, we found that gelatin-based materials exhibit good conductivity and are non-cytotoxic. In this study, gelatin was cross-linked with bisvinyl sulfonemethyl (BVSM) to fabricate a biodegradable conduit for peripheral nerve repair. First, BVSM on the prepared conduit was characterized to determine its mechanical properties and contact angle. The maximum tensile strength and water contact angle of the gelatin-BVSM conduits were 23 ± 4.8 MPa and 74.7 ± 9°, which provided sufficient mechanical strength to resist muscular contraction; additionally, the surface was hydrophilic. Cytotoxicity and apoptosis assays using Schwann cells demonstrated that the gelatin-BVSM conduits are non-cytotoxic. Next, we examined the neuronal electrophysiology, animal behavior, neuronal connectivity, macrophage infiltration, calcitonin gene-related peptide localization and expression, as well as the expression levels of nerve regeneration-related proteins. The number of fluorogold-labelled cells and histological analysis of the gelatin-BVSM nerve conduits was similar to that observed with the clinical use of silicone rubber conduits after 8 weeks of repair. Therefore, our results demonstrate that gelatin-BVSM conduits are promising substrates for application as bioengineered grafts for nerve tissue regeneration.

A Preclinical Assessment of Early Continuous Passive Motion and Treadmill Therapeutic Exercises for Generating Chondroprotective Effects After Anterior Cruciate Ligament Rupture

BACKGROUND

Anterior cruciate ligament (ACL) injury is a well-known risk factor for the development of posttraumatic osteoarthritis (PTOA). However, whether using continuous passive motion (CPM) with or without additional treadmill exercise (TRE) in early ACL injury might provide chondroprotective effects and further decrease the risk of PTOA has yet to be determined.

HYPOTHESIS

CPM may offer an enhanced chondroprotective effect, but TRE may attenuate that effect due to the mechanical stress on the joint and inflammatory cytokines in the joint.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty adult New Zealand White male rabbits were randomly allocated to sedentary (SED), CPM, TRE, or CPM+TRE groups. Each rabbit underwent an ACL transection (ACLT) on the right knee, with the contralateral knee used as an internal control (sham). The 4 joint surfaces (ie, medial and lateral femoral condyles and tibial plateaus) were evaluated 4 weeks after surgery for gross appearance, histological characteristics, and quantitative osteoarthritis (OA) scores.

RESULTS

Overall, at the end of testing, the CPM group experienced the best protective therapeutic effects in all compartments. In gross appearance, CPM resulted in normal articular surfaces, while the TRE and SED groups exhibited surface abrasion. Histological analysis showed significant differences in articular cartilage status. The CPM group had significantly better histological OA scores ( P < .01), corresponding to the smoothest cartilage surface and sound chondrocyte and collagen arrangement. This group also showed abundant glycosaminoglycan (GAG) content and a sound growth microenvironment, with significantly lower expression levels of the inflammatory cytokine tumor necrosis factor α and the apoptotic marker caspase 3. In contrast, the TRE and SED groups showed several features of damage: distinct graded cartilage abrasion; damaged collagen fibers, corresponding to noticeable collagen type X (osteoarthritic cartilage); reduced cartilage thickness; fewer cartilaginous cells; and the appearance of chondrocyte clusters. These groups also showed loss of GAG, corresponding to higher levels of inflammatory cytokines and apoptosis of articular chondrocytes. Furthermore, the CPM+TRE group displayed visible pathological changes in the superficial cartilage, indicating that early loading exercise may contribute to osteoarthritis. The sham treatment showed no difference in the changes in all compartments between groups.

CONCLUSION

Immediate CPM therapy produces a superior in situ microenvironment for reducing the occurrence of PTOA after ACL injury without reconstruction in rabbits.

CLINICAL RELEVANCE

These data suggest that immediate application of CPM therapy may be necessary to create a sound microenvironment in joints and possibly to decrease the risk of PTOA without or while awaiting ACL reconstruction. In contrast, both early active loading exercise and inactivity lead to the development of PTOA.

3D Printing of Cytocompatible Water-Based Light-Cured Polyurethane with Hyaluronic Acid for Cartilage Tissue Engineering Applications

Diseases in articular cartilages have affected millions of people globally. Although the biochemical and cellular composition of articular cartilages is relatively simple, there is a limitation in the self-repair ability of the cartilage. Therefore, developing strategies for cartilage repair is very important. Here, we report on a new liquid resin preparation process of water-based polyurethane based photosensitive materials with hyaluronic acid with application of the materials for 3D printed customized cartilage scaffolds. The scaffold has high cytocompatibility and is one that closely mimics the mechanical properties of articular cartilages. It is suitable for culturing human Wharton’s jelly mesenchymal stem cells (hWJMSCs) and the cells in this case showed an excellent chondrogenic differentiation capacity. We consider that the 3D printing hybrid scaffolds may have potential in customized tissue engineering and also facilitate the development of cartilage tissue engineering.

Fabrication and characterization of polycaprolactone and tricalcium phosphate composites for tissue engineering applications

Background/purpose

β-Tricalcium phosphate (β-TCP) is an osteoconductive material which has been used for clinical purposes for several years, as is polycaprolactone (PCL), which has already been approved for a number of medical and drug delivery devices. In this study we have incorporated various concentrations of β-TCP into PCL with the aim of developing an injectable, mechanically strong, and biodegradable material which can be used for medical purposes without organic solvents.

Materials and methods

This study assesses the physical and chemical properties of this material, evaluates the in vitro bioactivity of the PCL/β-TCP composites, and analyzes cell proliferation and osteogenic differentiation when using human bone marrow mesenchymal stem cells (hBMSCs).

Results

The results show that weight losses of approximately 5.3%, 12.1%, 18.6%, and 25.2%, were observed for the TCP0, TCP10, TCP30, and TCP50 composites after immersion in simulated body fluid for 12 weeks, respectively, indicating significant differences (P < 0.05). In addition, PCL/β-TCP composites tend to have lower contact angles (47 ± 1.5° and 58 ± 1.7° for TCP50 and TCP30, respectively) than pure PCL (85 ± 1.3°), which are generally more hydrophilic. After 7 days, a significant (22% and 34%, respectively) increase (P < 0.05) in alkaline phosphatase level was measured for TCP30 and TCP50 in comparison with the pure PCL.

Conclusion

PCL/TCP is biocompatible with hBMSCs. It not only promotes proliferation of hBMSCs but also helps to differentiate reparative hard tissue. We suggest 50% (weight) PCL-containing β-TCP biocomposites as the best choice for hard tissue repair applications.

Tensile force on human macrophage cells promotes osteoclastogenesis through receptor activator of nuclear factor κB ligand induction

Little is known about the effects of tensile forces on osteoclastogenesis by human monocytes in the absence of mechanosensitive cells, including osteoblasts and fibroblasts. In this study we consider the effects of tensile force on osteoclastogenesis in human monocytes. The cells were treated with receptor activator of nuclear factor κB ligand (RANKL) to promote osteoclastogenesis. Then,expression and secretion of cathepsin K were examined. RANKL and the formation of osteoclasts during the osteoclast differentiation process under continual tensile stress were evaluated by Western blot. It was also found that -100 kPa or lower induces RANKL-enhanced tartrate-resistant acid phosphatase activity in a dose-dependent manner. Furthermore, an increased tensile force raises the expression and secretion of cathepsin K elevated by RANKL, and is concurrent with the increase of TNF-receptor-associated factor 6 induction and nuclear factor κB activation. Overall, the current report demonstrates that tensile force reinforces RANKL-induced osteoclastogenesis by retarding osteoclast differentiation. The tensile force is able to modify every cell through dose-dependent in vitro RANKL-mediated osteoclastogenesis, affecting the fusion of preosteoclasts and function of osteoclasts. However, tensile force increased TNF-receptor-associated factor 6 expression. These results are in vitro findings and were obtained under a condition of tensile force. The current results help us to better understand the cellular roles of human macrophage populations in osteoclastogenesis as well as in alveolar bone remodeling when there is tensile stress.