Effects of S53P4 bioactive glass on osteoblastic cell and biomaterial surface interaction

Electrical therapies act on the Ca2+ /CaM signaling pathway to enhance bone regeneration with bioactive glass [S53P4] and allogeneic grafts

This study aimed to investigate the application of low-intensity electrostimulation (ES) and electromagnetic stimulation (EM) associated with bioactive glass (BG) or allogeneic grafts (BB) in bone regeneration. A cell viability test on osteoblasts (UMR-106) was performed in the presence of BB and BG grafts associated with ES (10 μA/5 min) and EM (500 Hz/2 min). Critical defects (25 mm² ) in calvaria were generated in male Wistar rats, and bone regeneration was evaluated on the 30th, 60th, and 120th days after surgery. Cell proliferation increased with the application of ES in both grafts and after EM with BG. Bone remodeling was more effective using the allogeneic graft in both therapies, with increased angiogenesis, osteoblast proliferation, and OPN expression in the BB + EM group. A higher number of osteoblasts and osteoclasts, and an increase in bone sialoprotein, Runx-2, and Opn gene expression were found in the BB + ES group. The BG graft associated with EM therapy had an increased proliferation of osteoblasts and increased expression of Runx-2 and Opn. Groups that had BG and ES therapy had increased numbers of osteoblasts, osteoclasts, and increased OPN expression. The expression of voltage-gated calcium channels increased in groups with ES, while calmodulin expression increased in therapies without grafting. ES and EM therapies favored the repair of bone defects upon grafting by improving angiogenesis, osteogenic gene expression, and tissue reorganization. Despite activating different pathways, both therapies increased the intracellular concentrations of calmodulin, leading to cell proliferation and bone regeneration.

Bioactive glass granules S53P4 in osteotomy Le Fort I

We evaluated bioactive glass graft (S53P4) in patients undergoing Le Fort I osteotomy, with non-grafted patients as controls. Computed tomography facial scans of the 25 patients submitted for Le Fort I were divided into two groups: Group 1-S53P4 group and Group 2-without grafting. CT scans were analyzed in the immediate postoperative period (T1) and 6 months later (T2), for linear bone gap measurements, tomographic radiodensity and behavior of the maxillary sinus. A Kruskal-Wallis test on bone gap data adopted α significance levels (p ≤ 0.05). The Friedman test (p ≤ 0.05) was used to evaluate sinus reaction cores. For gap measurements, we observed a decrease in median data between T1 and T2 in both groups, with statistical significances observed between groups in T0; G1 presented statistical difference in its two studied times (p ≤ 0.0001). For bone density, the studied data behaved inversely. G1's bone density decreased from T1 to T2, whereas in G2 there was an increase from T1 to T2. S53P4 did not elicit increased reactions and/or sinus infections in the G1 group (p ≥ 1.00). S53P4 did not impact on Le Fort I osteotomies as a coadjuvant and a favorable factor in bone formation, and appeared innocuous in the maxillary sinus.

Synthesis of bioactive glass-based coating by plasma electrolytic oxidation: Untangling a new deposition pathway toward titanium implant surfaces

HYPOTHESIS

Although bioactive glass (BG) particle coatings were previously developed by different methods, poor particle adhesion to surfaces and reduced biological effects because of glass crystallization have limited their biomedical applications. To overcome this problem, we have untangled, for the first time, plasma electrolytic oxidation (PEO) as a new pathway for the synthesis of bioactive glass-based coating (PEO-BG) on titanium (Ti) materials.

EXPERIMENTS

Electrolyte solution with bioactive elements (Na₂SiO₃-5H₂O, C₄H₆O₄Ca, NaNO₃, and C₃H₇Na₂O₆P) was used as a precursor source to obtain a 45S5 bioglass-like composition on a Ti surface by PEO. Subsequently, the PEO-BG coating was investigated with respect to its surface, mechanical, tribological, electrochemical, microbiological, and biological properties, compared with those of machined and sandblasted/acid-etched control surfaces.

FINDINGS

PEO treatment produced a coating with complex surface topography, Ti crystalline phases, superhydrophilic status, chemical composition, and oxide layer similar to that of 45S5-BG (~45.0Si, 24.5 Ca, 24.5Na, 6.0P w/v%). PEO-BG enhanced Ti mechanical and tribological properties with higher corrosion resistance. Furthermore, PEO-BG had a positive influence in polymicrobial biofilms, by reducing pathogenic bacterial associated with biofilm-related infections. PEO-BG also showed higher adsorption of blood plasma proteins without cytotoxic effects on human cells, and thus may be considered a promising biocompatible approach for biomedical implants.

Antimicrobial activity of bioactive glass S53P4 against representative microorganisms causing osteomyelitis - Real-time assessment by isothermal microcalorimetry

Bioactive glass (BAG) is a synthetic bone substitute with intrinsic antimicrobial properties, used for bone defect filling. We evaluated the antimicrobial activity of two formulations of BAG S53P4 against representative pathogens of osteomyelitis: Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli and Candida albicans. Antimicrobial activity of BAG S53P4 was assessed by isothermal microcalorimetry, a highly sensitive assay measuring metabolic-related microbial heat production in real-time. Standard CFUs-counting was performed in parallel. BAG granules (diameter 500-800 μm) and powder (<45 μm) were evaluated in two concentrations (400 and 800 mg/ml). Isothermal microcalorimetry was performed in glass ampoules containing growth medium, BAG and test microorganism, heat production was measured for 24 h. BAG S53P4 inhibited heat production of most-tested microorganisms with heat reduction of 60%-98% compared to positive control after 24 h of exposure to the highest-tested concentration (800 mg/ml). BAG S53P4 in powder formulation (<45 μm) inhibited more microbial growth than in granule formulation (500-800 μm), with the exception of C. albicans for which both formulations presented similar inhibition rates ranging between 87 % and 97 %. The BAG inhibitory ratios estimated from the variation in the growth rate constants of each microorganism compared to the growth control ranged between 2.55 % and 100 %. Comparable results were obtained by CFUs-counting, with complete reduction in cell viability of most microorganisms after ≤ 24 h of microbial exposure to BAG S53P4 powder. In summary, BAG S53P4 demonstrated efficient inhibition of microbial growth, especially in powder formulation.

Combining Biologically Active β-Lactams Integrin Agonists with Poly(l-lactic acid) Nanofibers: Enhancement of Human Mesenchymal Stem Cell Adhesion

Regulating stem cell adhesion and growth onto functionalized biomaterial scaffolds is an important issue in the field of tissue engineering and regenerative medicine. In this study, new electrospun scaffolds of poly(l-lactic acid) (PLLA), as bioresorbable polymer, and β-lactam compounds agonists of selected integrins, as functional components with cell adhesive properties, are designed. The new β-lactam-PLLA scaffolds contribute significantly in guiding protein translation involved in human bone marrow mesenchymal stem cells (hBM-MSC) adhesion and integrin gene expression. Scanning electron microscopy, confocal laser scanning microscopy, and Western Blot analyses reveal that GM18-PLLA shows the best results, promoting cell adhesion by significantly driving changes in focal adhesion proteins distribution (β₁ integrin and vinculin) and activation (pFAK), with a notable increase of GM18-targets subunits integrin gene expression, α₄ and β₁. These novel functionalized submicrometric fibrous scaffolds demonstrate, for the first time, the powerful combination of selective β-lactams agonists of integrins with biomimetic scaffolds, suggesting a designed rule that could be suitably applied to tissue repair and regeneration.

The "Race for the Surface" experimentally studied: In vitro assessment of Staphylococcus spp. adhesion and preosteoblastic cells integration to doped Ti-6Al-4V alloys

OBJECTIVE

Implant-related infection is a devastating complication in orthopedic surgery. Aiming to minimize this problem, many material modifications have been developed. Here we report a study of a surface modification of Ti-6 Al-4 V alloy using a methodology that enables the study of interactions between bacteria and the material in the presence of eukaryotic cells.

METHODS

We mixed different concentrations of collection or clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells using a previously published methodology, analyzing the minimal concentration of bacteria able to colonize the surface of the material through image analysis. Ti-6 Al-4 V alloy was modified by anodization to obtain two F-doped nanostructured surfaces that have been previously described to have antibacterial properties.

RESULTS

Our results show similar bacterial adhesion results to nanoporous and nanotubular F-doped surfaces. The presence of preosteoblastic cells increases the adherence of all bacterial strains to both structures. No effect of the surface on eukaryotic cells adherence was detected.

CONCLUSION

To our knowledge, this is the first time that anin vitro study emulating the race for the surface evaluates and compares the osseointegration and antibacterial properties between two nanostructured- modified titanium alloy surfaces. Clinical strains show different behavior from collection ones in bacterial adherence. The presence of cells increased bacterial adherence. NP and NT surface modifications didn´t show significant differences in bacterial adhesion and preosteoblastic cells integration.

Bioactive glass obliteration of the mastoid significantly improves surgical outcome in non-cholesteatomatous chronic otitis media patients

This retrospective follow-up study evaluates the efficacy and safety of bioactive glass (BAG) S53P4 when applied as filler material in mastoid obliteration surgery performed on non-cholesteatomatous chronic otitis media (NC-COM) patients with chronically discharging ears despite conservative therapy. 94 Patients (96 ears) were included. Patients underwent either intact canal wall (ICW) or canal wall down (CWD) mastoid surgery between 2005 and 2015. The intervention group comprised 23 patients (23 ears) who were treated with additional mastoid obliteration using BAG S53P4; the remaining 71 patients (73 ears) were considered controls. All patients underwent preoperative CT scanning of the mastoid. Primary functional outcome, as defined by control of suppuration, was assessed using Merchant's scale. Hearing results as measured by air-bone gap and the incidence of adverse events were assessed as secondary outcomes. Thirty-two ears (44%) in the control group (n = 73) achieved complete control of infection at the most recent postoperative clinic visit vs 17 (74%) in the S53P4 obliteration group (n = 23). Comparing these outcomes yielded an odds ratio (OR) of 3.6 (p = 0.012, 95% CI 1.3-10.3). Complete failure to manage infection significantly differed (p = 0.048) between the control group (11 ears; 15%) and the S53P4 obliteration group (0 ears). No adverse events were observed in either group. Pre- and postoperative ABG results did not differ significantly between groups. Obliteration of the mastoid cavity using BAG S53P4 along with mastoidectomy in patients with chronically discharging NC-COM significantly improves the achievement of a dry and safe ear as compared to mastoidectomy alone. Importantly, no adverse events were observed with S53P4 BAG obliteration.

Prevention of Biomaterial Infection by Pre-Operative Incubation with Human Cells

BACKGROUND

Cells of tissues and biofilm forming bacteria compete for the living space on the surface of an implant. We hypothesized the incubation of the implant (titanium, polydimethylsiloxane, and polystyrene surface) with human cells before implantation as a strategy to prevent bacterial adhesion and biofilm formation.

METHODS

After 24 hours of incubation with human osteogenic sarcoma SaOS-2 cells (1 × 10⁵ cells/mL), the materials were incubated for 4.5 hours or two days with Staphylococcus aureus in serial 1:10 dilutions of 10⁸ colony-forming units/mL. The bacterial adherence and biofilm biomass on materials pre-incubated with SaOS-2 cells were compared with our previous results on materials incubated only with bacteria or in simultaneous co-culture of SaOS-2 cells and S. aureus. Fluorescent microscopy and crystal violet stain were used. The number of viable SaOS-2 and bacterial cells present was tested using colorimetric methods (MTT, LDH) and drop plate method, respectively.

RESULTS

The pre-treatment with human cells was associated with a reduction of bacterial colonization of the biomaterial at 4.5 hours and 48 hours compared with the non-pre-treated materials. The presence of bacteria decreased the number of viable human cells on all materials. ( Supplementary Fig. 1 ; see online supplementary materials at www.liebertpub.com/sur ).

CONCLUSIONS

These results suggest that the pre-operative incubation of prostheses with host cells could prevent infection of biomaterials.

Osteomyelitis: Recent advances in pathophysiology and therapeutic strategies

This review article summarizes the recent advances in pathogenic mechanisms and novel therapeutic strategies for osteomyelitis, covering both periprosthetic joint infections and fracture-associated bone infections. A better understanding of the pathophysiology including the mechanisms for biofilm formation has led to new therapeutic strategies for this devastating disease. Research on novel local delivery materials with appropriate mechanical properties, lower exothermicity, controlled release of antibiotics, and absorbable scaffolding for bone regeneration is progressing rapidly. Emerging strategies for prevention, early diagnosis of low-grade infections, and innovative treatments of osteomyelitis such as biofilm disruptors and immunotherapy are highlighted in this review.

Competitive colonization of prosthetic surfaces by staphylococcus aureus and human cells

Implantation of a biomaterial provides an adhesion substratum both to host cell integration and to contaminating bacteria. We studied simultaneous competitive adhesion of Staphylococcus aureus in serial 1:10 dilutions of 10⁸ colony forming units (CFU)/mL and human osteogenic sarcoma (SaOS-2) or primary osteoblast (hOB) cells, both 1x10⁵ cells/mL, to the surfaces of titanium, polydimethylsiloxane and polystyrene. The bacterial adherence and human cell proliferation, cytotoxicity and production of reactive oxygen species (ROS) were studied using fluorometric (fluorescent microscopy and flow cytometry) and colorimetric methods (MTT, LDH and crystal violet). The bacterial cell viability was also evaluated using the drop plate method. The presence of bacteria resulted in reduced adherence of human cells to the surface of the biomaterials, increased production of ROS, and into increased apoptosis. On the other hand, the presence of either type of human cells was associated with a reduction of bacterial colonization of the biomaterial with Staphylococcus aureus. These results suggest that increasing colonization of the biomaterial surface in vitro by one negatively affects colonization by the other. Host cell integration to an implant surface reduces bacterial contamination, which opens novel opportunities for the design of infection-resistant biomaterials in current implantology and future regenerative medicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 62-72, 2017.