Context: The development of porous devices using materials modified with various natural agents has become a priority for bone healing processes in the oral and maxillofacial field. There must be a balance between the proliferation of eukaryotic and the inhibition of prokaryotic cells to achieve proper bone health. Infections might inhibit the formation of new alveolar bone during bone graft augmentation. Objective: This study aimed to evaluate the in vitro osteogenic behavior of human bone marrow stem cells and assess the antimicrobial response to 3D-printed porous scaffolds using propolis-modified wollastonite. Methodology: A fractional factorial design of experiments was used to obtain a 3D printing paste for developing scaffolds with a triply periodic minimal surface (TPMS) gyroid geometry based on wollastonite and modified with an ethanolic propolis extract. The antioxidant activity of the extracts was characterized using free radical scavenging methods (DPPH and ABTS). Cell proliferation and osteogenic potential using Human Bone Marrow Stem Cells (bmMSCs) were assessed at different culture time points up to 28 days. MIC and inhibition zones were studied from single strain cultures, and biofilm formation was evaluated on the scaffolds under co-culture conditions. The mechanical strength of the scaffolds was evaluated. Results: Through statistical design of experiments, a paste suitable for printing scaffolds with the desired geometry was obtained. Propolis extracts modifying the TPMS gyroid scaffolds showed favorable cell proliferation and metabolic activity with osteogenic potential after 21 days. Additionally, propolis exhibited antioxidant activity, which may be related to the antimicrobial effectiveness of the scaffolds against S. aureus and S. epidermidis cultures. The mechanical properties of the scaffolds were not affected by propolis impregnation. Conclusion: These results demonstrate that propolis-impregnated porous wollastonite scaffolds might have the potential to stimulate bone repair in maxillofacial tissue engineering applications.
Biocompatible ceramic scaffolds offer a promising approach to address the challenges in bone reconstruction. Wollastonite, well-known for its exceptional biocompatibility, has attracted significant attention in orthopedics and craniofacial fields. However, the antimicrobial properties of wollastonite have contradictory findings, necessitating further research to enhance its antibacterial characteristics. This study aimed to explore a new approach to improve in vitro biological response in terms of antimicrobial activity and cell proliferation by taking advantage of additive manufacturing for the development of scaffolds with complex geometries by 3D printing using propolis-modified wollastonite. The scaffolds were designed with a TPMS (Triply Periodic Minimal Surface) gyroid geometric shape and 3D printed prior to impregnation with propolis extract. The paste formulation was characterized by rheometric measurements, and the presence of propolis was confirmed by FTIR spectroscopy. The scaffolds were comprehensively assessed for their mechanical strength. The biological characterization involved evaluating the antimicrobial effects against Staphylococcus aureus and Staphylococcus epidermidis, employing Minimum Inhibitory Concentration (MIC), Zone of Inhibition (ZOI), and biofilm formation assays. Additionally, SaOs-2 cultures were used to study cell proliferation (Alamar blue assay), and potential osteogenic was tested (von Kossa, Alizarin Red, and ALP stainings) at different time points. Propolis impregnation did not compromise the mechanical properties of the scaffolds, which exhibited values comparable to human trabecular bone. Propolis incorporation conferred antibacterial activity against both Staphylococcus aureus and Staphylococcus epidermidis. The implementation of TPMS gyroid geometry in the scaffold design demonstrated favorable cell proliferation with increased metabolic activity and osteogenic potential after 21 days of cell cultures.
Several diseases and injuries cause irreversible damage to bone tissues, which may require partial or total regeneration or replacement. Tissue engineering suggests developing substitutes that may contribute to the repair or regeneration process by using three-dimensional lattices (scaffolds) to create functional bone tissues. Herein, scaffolds comprising polylactic acid and wollastonite particles enriched with propolis extracts from the Arauca region of Colombia were developed as gyroid triply periodic minimal surfaces using fused deposition modeling. The propolis extracts exhibited antibacterial activity against Staphylococcus aureus (ATCC 25175) and Staphylococcus epidermidis (ATCC 12228), which cause osteomyelitis. The scaffolds were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, contact angle, swelling, and degradation. Their mechanical properties were assessed using static and dynamic tests. Cell viability/proliferation assay was conducted using hDP-MSC cultures, while their bactericidal properties against monospecies cultures (S. aureus and S. epidermidis) and cocultures were evaluated. The wollastonite particles did not affect the physical, mechanical, or thermal properties of the scaffolds. The contact angle results showed that there were no substantial differences in the hydrophobicity between scaffolds with and without particles. Scaffolds containing wollastonite particles suffered less degradation than those produced using PLA alone. A representative result of the cyclic tests at Fmax = 450 N showed that the maximum strain reached after 8000 cycles is well below the yield strain (i.e., <7.5%), thereby indicating that even under these stringent conditions, these scaffolds will be able to work properly. The scaffolds impregnated with propolis showed a lower % of cell viability using hDP-MSCs on the 3rd day, but these values increased on the 7th day. These scaffolds exhibited antibacterial activity against the monospecies cultures of S. aureus and S. epidermidis and their cocultures. The samples without propolis loads did not show inhibition halos, whereas those loaded with EEP exhibited halos of 17.42 ± 0.2 mm against S. aureus and 12.9 ± 0.5 mm against S. epidermidis. These results made the scaffolds possible bone substitutes that exert control over species with a proliferative capacity for the biofilm-formation processes required for typical severe infectious processes.
