Effect of Pore Characteristics and Alkali Treatment on the Physicochemical and Biological Properties of a 3D-Printed Polycaprolactone Bone Scaffold

Fabricating Multiphasic Angiogenic Scaffolds Using Amyloid/Roxadustat-Assisted High-Temperature Protein Printing

Repairing multiphasic defects is cumbersome. This study presents new soft and hard scaffold designs aimed at facilitating the regeneration of multiphasic defects by enhancing angiogenesis and improving cell attachment. Here, the nonimmunogenic, nontoxic, and cost-effective human serum albumin (HSA) fibril (HSA-F) was used to fabricate thermostable (up to 90 °C) and hard printable polymers. Additionally, using a 10.0 mg/mL HSA-F, an innovative hydrogel was synthesized in a mixture with 2.0% chitosan-conjugated arginine, which can gel in a cell-friendly and pH physiological environment (pH 7.4). The presence of HSA-F in both hard and soft scaffolds led to an increase in significant attachment of the scaffolds to the human periodontal ligament fibroblast (PDLF), human umbilical vein endothelial cell (HUVEC), and human osteoblast. Further studies showed that migration (up to 157%), proliferation (up to 400%), and metabolism (up to 210%) of these cells have also improved in the direction of tissue repair. By examining different in vitro and ex ovo experiments, we observed that the final multiphasic scaffold can increase blood vessel density in the process of per-vascularization as well as angiogenesis. By providing a coculture environment including PDLF and HUVEC, important cross-talk between these two cells prevails in the presence of roxadustat drug, a proangiogenic in this study. In vitro and ex ovo results demonstrated significant enhancements in the angiogenic response and cell attachment, indicating the effectiveness of the proposed design. This approach holds promise for the regeneration of complex tissue defects by providing a conducive environment for vascularization and cellular integration, thus promoting tissue healing.

Evaluation of new bone formation in critical-sized rat calvarial defect using 3D printed polycaprolactone/tragacanth gum-bioactive glass composite scaffolds

Critical-sized bone defects are a major challenge in reconstructive bone surgery and usually fail to be treated due to limited remaining bone quality and extensive healing time. The combination of 3D-printed scaffolds and bioactive materials is a promising approach for bone tissue regeneration. In this study, 3D-printed alkaline-treated polycaprolactone scaffolds (M-PCL) were fabricated and integrated with tragacanth gum- 45S5 bioactive glass (TG-BG) to treat critical-sized calvarial bone defects in female adult Wistar rats. After a healing period of four and eight weeks, the new bone of blank, M-PCL, and M-PCL/TG-BG groups were harvested and assessed. Micro-computed tomography, histological, biochemical, and biomechanical analyses, gene expression, and bone matrix formation were used to assess bone regeneration. The micro-computed tomography results showed that the M-PCL/TG-BG scaffolds not only induced bone tissue formation within the bone defect but also increased BMD and BV/TV compared to blank and M-PCL groups. According to the histological analysis, there was no evidence of bony union in the calvarial defect regions of blank groups, while in M-PCL/TG-BG groups bony integration and repair were observed. The M-PCL/TG-BG scaffolds promoted the Runx2 and collagen type I expression as compared with blank and M-PCL groups. Besides, the bone regeneration in M-PCL/TG-BG groups correlated with TG-BG incorporation. Moreover, the use of M-PCL/TG-BG scaffolds promoted the biomechanical properties in the bone remodeling process. These data demonstrated that the M-PCL/TG-BG scaffolds serve as a highly promising platform for the development of bone grafts, supporting bone regeneration with bone matrix formation, and osteogenic features. Our results exhibited that the 3D-printed M-PCL/TG-BG scaffolds are a promising strategy for successful bone regeneration.

Enhancing bone tissue engineering with 3D-Printed polycaprolactone scaffolds integrated with tragacanth gum/bioactive glass

Tissue-engineered bone substitutes, characterized by favorable physicochemical, mechanical, and biological properties, present a promising alternative for addressing bone defects. In this study, we employed an innovative 3D host-guest scaffold model, where the host component served as a mechanical support, while the guest component facilitated osteogenic effects. More specifically, we fabricated a triangular porous polycaprolactone framework (host) using advanced 3D printing techniques, and subsequently filled the framework's pores with tragacanth gum-45S5 bioactive glass as the guest component. Comprehensive assessments were conducted to evaluate the physical, mechanical, and biological properties of the designed scaffolds. Remarkably, successful integration of the guest component within the framework was achieved, resulting in enhanced bioactivity and increased strength. Our findings demonstrated that the scaffolds exhibited ion release (Si, Ca, and P), surface apatite formation, and biodegradation. Additionally, in vitro cell culture assays revealed that the scaffolds demonstrated significant improvements in cell viability, proliferation, and attachment. Significantly, the multi-compartment scaffolds exhibited remarkable osteogenic properties, indicated by a substantial increase in the expression of osteopontin, osteocalcin, and matrix deposition. Based on our results, the framework provided robust mechanical support during the new bone formation process, while the guest component matrix created a conducive micro-environment for cellular adhesion, osteogenic functionality, and matrix production. These multi-compartment scaffolds hold great potential as a viable alternative to autografts and offer promising clinical applications for bone defect repair in the future.

Towards Polycaprolactone-Based Scaffolds for Alveolar Bone Tissue Engineering: A Biomimetic Approach in a 3D Printing Technique

The alveolar bone is a unique type of bone, and the goal of bone tissue engineering (BTE) is to develop methods to facilitate its regeneration. Currently, an emerging trend involves the fabrication of polycaprolactone (PCL)-based scaffolds using a three-dimensional (3D) printing technique to enhance an osteoconductive architecture. These scaffolds are further modified with hydroxyapatite (HA), type I collagen (CGI), or chitosan (CS) to impart high osteoinductive potential. In conjunction with cell therapy, these scaffolds may serve as an appealing alternative to bone autografts. This review discusses research gaps in the designing of 3D-printed PCL-based scaffolds from a biomimetic perspective. The article begins with a systematic analysis of biological mineralisation (biomineralisation) and ossification to optimise the scaffold's structural, mechanical, degradation, and surface properties. This scaffold-designing strategy lays the groundwork for developing a research pathway that spans fundamental principles such as molecular dynamics (MD) simulations and fabrication techniques. Ultimately, this paves the way for systematic in vitro and in vivo studies, leading to potential clinical applications.

3D printing for bone regeneration: challenges and opportunities for achieving predictability

3D printing offers attractive opportunities for large-volume bone regeneration in the oro-dental and craniofacial regions. This is enabled by the development of CAD-CAM technologies that support the design and manufacturing of anatomically accurate meshes and scaffolds. This review describes the main 3D-printing technologies utilized for the fabrication of these patient-matched devices, and reports on their pre-clinical and clinical performance including the occurrence of complications for vertical bone augmentation and craniofacial applications. Furthermore, the regulatory pathway for approval of these devices is discussed, highlighting the main hurdles and obstacles. Finally, the review elaborates on a variety of strategies for increasing bone regeneration capacity and explores the future of 4D bioprinting and biodegradable metal 3D printing.

Structural Mechanical Properties of 3D Printing Biomimetic Bone Replacement Materials

One of the primary challenges in developing bone substitutes is to create scaffolds with mechanical properties that closely mimic those of regenerated tissue. Scaffolds that mimic the structure of natural cancellous bone are believed to have better environmental adaptability. In this study, we used the porosity and thickness of pig cancellous bone as biomimetic design parameters, and porosity and structural shape as differential indicators, to design a biomimetic bone beam scaffold. The mechanical properties of the designed bone beam model were tested using the finite element method (FEM). PCL/β-TCP porous scaffolds were prepared using the FDM method, and their mechanical properties were tested. The FEM simulation results were compared and validated, and the effects of porosity and pore shape on the mechanical properties were analyzed. The results of this study indicate that the PCL/β-TCP scaffold, prepared using FDM 3D printing technology for cancellous bone tissue engineering, has excellent integrity and stability. Predicting the structural stability using FEM is effective. The triangle pore structure has the most stability in both simulations and tests, followed by the rectangle and honeycomb shapes, and the diamond structure has the worst stability. Therefore, adjusting the porosity and pore shape can change the mechanical properties of the composite scaffold to meet the mechanical requirements of customized tissue engineering.