Tissue-specific melt electrowritten polymeric scaffolds for coordinated regeneration of soft and hard periodontal tissues

Periodontitis is a chronic inflammatory condition that often causes serious damage to tooth-supporting tissues. The limited successful outcomes of clinically available approaches underscore the need for therapeutics that cannot only provide structural guidance to cells but can also modulate the local immune response. Here, three-dimensional melt electrowritten ( i.e., poly(ε-caprolactone)) scaffolds with tissue-specific attributes were engineered to guide differentiation of human-derived periodontal ligament stem cells (hPDLSCs) and mediate macrophage polarization. The investigated tissue-specific scaffold attributes comprised fiber morphology (aligned vs. random) and highly-ordered architectures with distinct strand spacings (small 250 μm and large 500 μm). Macrophages exhibited an elongated morphology in aligned and highly-ordered scaffolds, while maintaining their round-shape on randomly-oriented fibrous scaffolds. Expressions of periostin and IL-10 were more pronounced on the aligned and highly-ordered scaffolds. While hPDLSCs on the scaffolds with 500 μm strand spacing show higher expression of osteogenic marker (Runx2) over 21 days, cells on randomly-oriented fibrous scaffolds showed upregulation of M1 markers. In an orthotopic mandibular fenestration defect model, findings revealed that the tissue-specific scaffolds ( i.e., aligned fibers for periodontal ligament and highly-ordered 500 μm strand spacing fluorinated calcium phosphate [F/CaP]-coated fibers for bone) could enhance the mimicking of regeneration of natural periodontal tissues

Influence of Fused Deposition Modelling Nozzle Temperature on the Rheology and Mechanical Properties of 3D Printed β-Tricalcium Phosphate (TCP)/Polylactic Acid (PLA) Composite

The primary goal of this study is to develop and analyze 3D printed structures based on a well-known composite known as β-Tricalcium Phosphate (TCP)– polylactic acid (PLA). There are some interesting aspects of this study. First, we developed 3D printable TCP–PLA composite filaments in-house, with high reproducibility, by a one-step process method using a single screw extruder. Second, we explored the physicochemical properties of the developed TCP–PLA composite filaments. Third, we investigated the effect of an FDM-based nozzle temperature of 190 °C, 200 °C, 210 °C, and 220 °C on the composite’s crystallinity and rheological and mechanical properties. Results confirmed the successful development of constant-diameter TCP–PLA composite filaments with a homogeneous distribution of TCP particles in the PLA matrix. We observed that a higher nozzle temperature in the FDM process increased the crystallinity of the printed PLA and TCP–PLA structures. As a result, it also helped to enhance the mechanical properties of the printed structures. The rheological studies were performed in the same temperature range used in the actual FDM process, and results showed an improvement in rheological properties at higher nozzle temperatures. The bare polymer and the composite polymer-ceramic melts exhibited lower viscosity and less rigidity at higher nozzle temperatures, which resulted in enhancing the polymer melt flowability and interlayer bonding between the printed layers. Overall, our results confirmed that 3D printable TCP–PLA filaments could be made in-house, and optimization of the nozzle temperature is essential to developing 3D printed composite parts with favorable mechanical properties

Smart Injectable Self-Setting Monetite Based Bioceramics for Orthopedic Applications

The present study is the first of its kind dealing with the development of a specific bioceramic which qualifies as a potential material in hard-tissue replacements. Specifically, we report the synthesis and evaluation of smart injectable calcium phosphate bone cement (CPC) which we believe will be suitable for various kinds of orthopedic and spinal-fusion applications. The smart nature of this next generation orthopedic implant is attained by incorporating piezoelectric barium titanate (BT) particles into monetite-based (dicalcium phosphate anhydrous, DCPA) CPC composition. The main goal is to take advantage of the piezoelectric properties of BT, as electromechanical effect plays a vital role in fracture healing at the defect site and bone integration with the implant. Furthermore, radiopacity of BT would help in easy detection of the CPC presence at the fracture site during surgery. Results reveal that BT addition favors important properties of bone cement such as good compressive strength, injectability, bioactivity, biocompatibility, and even washout resistance. Most importantly, the self-setting nature of the bone cements are not compromised with BT incorporation. The in vitro results confirm that the developed bone-cement abides by the standard orthopedic requirements making it apt for real-time prosthetic materials

Fused Filament Fabrication (Three-Dimensional Printing) of Amorphous Magnesium Phosphate/Polylactic Acid Macroporous Biocomposite Scaffolds

The ultimate goal of this paper is to develop novel ceramic-polymer-based biocomposite orthopedic scaffolds with the help of additive manufacturing. Specifically, we incorporate a bioceramic known as amorphous magnesium phosphate (AMP) into polylactic acid (PLA) with the help of the melt-blending technique. Magnesium phosphate (MgP) was chosen as the bioactive component as previous studies have confirmed its favorable biomaterial properties, especially in orthopedics. Special care was taken to develop constant diameter AMP-PLA composite filaments, which would serve as feedstock for a fused filament fabrication (FFF)-based three-dimensional (3D) printer. Before the filaments were used for FFF, a thorough set of characterization protocols comprising of phase analysis, microstructure evaluations, thermal analysis, rheological analysis, and in vitro degradation determinations was performed on the biocomposites. Scanning electron microscopy (SEM) results confirmed a homogenous dispersion of AMP particles in the PLA matrix. Rheological studies demonstrated good printability behavior of the AMP-PLA filaments. In vitro degradation studies indicated a faster degradation rate in the case of AMP-PLA filaments as compared to the single phase PLA filaments. Subsequently, the filaments were fed into an FFF setup, and tensile bars and design-specific macroporous AMP-PLA scaffolds were printed. The biocomposite exhibited favorable mechanical properties. Furthermore, in vitro cytocompatibility results revealed higher pre-osteoblast cell attachment and proliferation on AMP-PLA scaffolds as compared to single-phase PLA scaffolds. Altogether, this study provides a proof of concept that design-specific bioactive AMP-PLA biocomposite scaffolds fabricated by FFF can be potential candidates as medical implants in orthopedics

Extracellular Matrix/Amorphous Magnesium Phosphate Bioink for 3D Bioprinting of Craniomaxillofacial Bone Tissue

Bioprinting, a promising field in regenerative medicine, holds great potential to create three-dimensional, defect-specific vascularized bone with tremendous opportunities to address unmet craniomaxillofacial reconstructive challenges. A cytocompatible bioink is a critical prerequisite to successfully regenerating functional bone tissue. Synthetic self-assembling peptides have a nanofibrous structure resembling the native extracellular matrix (ECM), making them an excellent bioink component. Amorphous magnesium phosphates (AMP) have shown greater levels of resorption while maintaining high biocompatibility, osteoinductivity, and low inflammatory response, as compared to their calcium phosphate counterparts. Here, we have established a novel bioink formulation (ECM/AMP) that combines an ECM-based hydrogel containing 2% octapeptide FEFEFKFK and 98% water with AMP particles to realize high cell function with desirable bioprintability. We analyzed the osteogenic differentiation of dental pulp stem cells (DPSCs) encapsulated in the bioink, as well as in vivo bone regeneration, to define the potential of the formulated bioink as a growth factor-free bone-forming strategy. Cell-laden AMP-modified bioprinted constructs showed improved cell morphology but similar cell viability (~ 90%) compared to their AMP-free counterpart. In functional assays, the cell-laden bioprinted constructs modified with AMP exhibited a high level of mineralization and osteogenic gene expression without the use of growth factors, thus suggesting that the presence of AMP triggered DPSCs' osteogenic differentiation. Cell-free ECM-based bioprinted constructs were implanted in vivo. In comparison with the ECM group, bone volume per total volume (BV/TV) for ECM/1.0AMP was approximately 1.7- and 1.4-fold higher at 4 and 8 weeks, respectively. Further, a significant increase in bone density was observed in ECM/1.0AMP from 4 to 8 weeks. These results demonstrate that the presence of AMP in the bioink significantly increased bone formation, thus showing promise for in situ bioprinting strategies. We foresee significant potential in translating this innovative bioink towards the regeneration of patient-specific bone tissue for regenerative dentistry