In vitro evaluation of doxorubicin release from diopside particles on MG-63 and HF spheroids as a 3D model of tumor and healthy tissues.

Local drug delivery systems based on bioceramics ensure safe and effective treatment of bone defects and anticancer therapy. A promising drug delivery scaffold material for bone treatment applications is diopside (CaMgSi2O6) which is bioactive, degradable, and possesses drug-release ability. Currently, in vitro assessment of drug release from biomaterials is performed mostly on a 2D cell monolayer. However, to interpret and integrate biochemical signals, cells need a 3D microenvironment that provides cell-cell and cell-extracellular matrix interactions. In this regard, 3D cell models are gaining popularity. In this work, we proposed the protocol for evaluation of the effect of doxorubicin released from diopside on MG-63 cells and primary human fibroblasts in 3D culture conditions. Tissue spheroids with similar diameters were incubated with doxorubicin-loaded diopside for 72 h, the amount of diopside was calculated in accordance with the required doxorubicin concentration. We demonstrated that doxorubicin is gradually released from diopside and exhibits an activity similar to that of the pure drug at the same total concentration. It is important to note that doxorubicin was more potent on MG-63 spheroids compared to HF spheroids, which confirmed the reliability of spheroids as 3D models of tumor and healthy tissues.

Antibacterial and Anti-Biofilm Properties of Diopside Powder Loaded with Lysostaphin.

BACKGROUND: Diopside-based ceramic is a perspective biocompatible material with numerous potential applications in the field of bone prosthetics. Implantable devices and materials are often prone to colonization and biofilm formation by pathogens such as Staphylococcus aureus, which in the case of bone grafting leads to osteomyelitis, an infectious bone and bone marrow injury. To lower the risk of bacterial colonization, implanted materials can be impregnated with antimicrobials. In this work, we loaded the antibacterial enzyme lysostaphin on diopside powder and studied the antibacterial and antibiofilm properties of such material to probe the utility of this approach for diopside-based prosthetic materials. METHODS: Diopside powder was synthesized by the solid-state method, lysostaphin was loaded on diopside by adsorption, the release of lysostaphin from diopside was monitored by ELISA, and antibacterial and anti-biofilm activity was assessed by standard microbiological procedures. RESULTS AND CONCLUSIONS: Lysostaphin released from diopside powder showed high antibacterial activity against planktonic bacteria and effectively destroyed 24-h staphylococcal biofilms. Diopside-based materials possess a potential for the development of antibacterial bone grafting materials.

Is Patient-Specific Instrumentation Accurate and Necessary for Open-Wedge High Tibial Osteotomy? A Meta-Analysis.

The purpose of this meta-analysis was to identify if patient-specific instrumentation (PSI) could increase the accuracy of the correction in high tibial osteotomy (HTO) and to explore the assessment indices and the necessity of using a PSI in HTO. A systematic search was carried out using online databases. A total of 466 patients were included in 11 papers that matched the inclusion criteria. To evaluate the accuracy of PSI-assisted HTO, the weight bearing line ratio (WBL%), hip-knee-ankle angle (HKA), mechanical medial proximal tibial angle (mMPTA), and posterior tibial slope angle (PTSA) were measured preoperatively and postoperatively and compared to the designed target values. Statistical analysis was performed after strict data extraction with Review Manager (version 5.4). Significant differences were detected in WBL% (MD = -36.41; 95% CI: -42.30 to -30.53; p < 0.00001), HKA (MD = -9.95; 95% CI: -11.65 to -8.25; p < 0.00001), and mMPTA (MD = -8.40; 95% CI:-10.27 to -6.53; p < 0.00001) but not in PTSA (MD = 0.34; 95% CI: -0.59 to 1.27; p = 0.47) between preoperative and postoperative measurements. There was no significant difference between the designed target values and the postoperative correction values of HKA (MD = 0.14; 95% CI: -0.19 to 0.47; p = 0.41) or mMPTA (MD = 0.11; 95% CI -0.34 to 0.55; p = 0.64). The data show that 3D-based planning of PSI for HTO is both accurate and safe. WBL%, HKA, and mMPTA were the optimal evaluation indicators of coronal plane correction. Sagittal correction is best evaluated by the PTSA. The present study reports that PSI is accurate but not necessary in typical HTO.

Hybrid Implants Based on Calcium-Magnesium Silicate Ceramics Diopside as a Carrier of Recombinant BMP-2 and Demineralized Bone Matrix as a Scaffold: Dynamics of Reparative Osteogenesis in a Mouse Craniotomy Model.

Calcium-magnesium silicate ceramics, diopside, is a promising material for use in bone plastics, but until now the possibility of its use as a carrier of recombinant bone morphogenetic protein-2 (BMP-2) has not been studied, as well as the features of reparative osteogenesis mediated by the materials based on diopside with BMP-2. Powder of calcium-magnesium silicate ceramics was obtained by solid-state synthesis using biowaste - rice husks and egg shells - as source components. Main phase of the obtained ceramics was diopside. The obtained particles were irregularly shaped with an average size of about 2.3 µm and ~20% porosity; average pore size was about 24 nm, which allowed the material to be classified as mesoporous. Diopside powder adsorbs more than 150 µg of recombinant BMP-2 per milligram, which exceeds binding capacity of hydroxyapatite, a calcium-phosphate ceramic often used in hybrid implants, by more than 3 times. In vitro release kinetics of BMP-2 was characterized by a burst release in the first 2 days and a sustained release of approximately 0.4 to 0.5% of the loaded protein over the following 7 days. In vivo experiments were performed with a mouse model of cranial defects of critical size with implantation of a suspension of diopside powder with/without BMP-2 in hyaluronic acid incorporated into the disks of demineralized bone matrix with 73-90% volume porosity and macropore size from 50 to 650 µm. Dynamics of neoosteogenesis and bone tissue remodeling was investigated histologically at the time points of 12, 21, 48, and 63 days. Diopside particles were evenly spread in the matrix and caused minimal foreign body reaction. In the presence of BMP-2 by the day 63 significant foci of newly formed bone tissue were formed in the implant pores with bone marrow areas, moreover, large areas of demineralized bone matrix in the implant center and maternal bone at the edges were involved in the remodeling. Diopside could be considered as a promising material for introduction into hybrid implants as an effective carrier of BMP-2.

Mechanical, Structural, and Biological Characteristics of Polylactide/Wollastonite 3D Printed Scaffolds.

The present work aimed to study the synergistic response of bioresorbable polylactide/bioactive wollastonite scaffolds towards mechanical stability, mesenchymal stromal cell colonization, and antibacterial activity in the physiological environment. Wollastonite was synthesized at 800 °C within 2 h by sol-gel combustion method. The surface area was found to be 1.51 m2/g, and Transmission Electron Microscopy (TEM) micrographs indicated the presence of porous structures. Fused deposition modeling was used to prepare 3D-printed polylactide/wollastonite and polylactide/hydroxyapatite scaffolds. Scanning Electron Microscopy (SEM) micrographs confirmed the interconnected porous structure and complex geometry of the scaffolds. The addition of wollastonite decreased the contact angle of the scaffolds. The mechanical testing of scaffolds examined by computational simulation, as well as machine testing, revealed their non-load-bearing capacity. The chemical constituent of the scaffolds was found to influence the attachment response of different cells on their surface. The incorporation of wollastonite effectively reduced live bacterial attachment, whereas the colonization of mesenchymal cells was improved. This observation confirms polylactide/wollastonite scaffold possesses both bactericidal as well as cytocompatible properties. Thus, the risk of peri-implant bacterial film formation can be prevented, and the biological fixation of the scaffold at the defect site can be enhanced by utilizing these composites.

Biomineralization, dissolution and cellular studies of silicate bioceramics prepared from eggshell and rice husk.

The current investigation aims to replace the synthetic starting materials with biowaste to synthesize and explore three different silicate bioceramics. Pure silica from rice husk was extracted by decomposition of rice husk in muffle furnace followed by alkali treatment and acid precipitation. Raw eggshell and extracted silica were utilized for the preparation of wollastonite, diopside and forsterite by the solid-state method. The TG-DSC analysis shows that the crystallization temperature of wollastonite, diopside and forsterite was found to be 883 °C, 870 °C and 980 °C, respectively. The phase purity of wollastonite was attained at 1100 °C whereas diopside and forsterite were composed of secondary phases even after calcination at 1250 °C and 1300 °C respectively. All three materials behaved differently when exposed to the physiological environment, as wollastonite exhibited remarkable apatite deposition within 3 days whereas a distinct apatite phase was noticed on the surface of diopside after 2 weeks and forsterite shows the formation of apatite phase after five weeks of immersion. The rapid dissolution of Mg2+ ion from forsterite lowered the leaching of silicate ions into the simulated body fluid leading to poor apatite deposition over its surface. Chemical composition was found to plays a key role in the biomineralization ability of these bioceramics. Hemolysis and Lactate Dehydrogenase (LDH) release assays were performed to evaluate the hemocompatibility of silicate ceramics cultured at different concentrations (62.5, 125, and 250 µg/mL) with red blood cells and mononuclear leucocytes (MLs) of mice. The hemolytic activity of all the tested bioceramics was insignificant (less than 1%). The interaction between diopside and mouse multipotent mesenchymal stromal cells (MMSCs) caused a negligible increase in the number of apoptosis-associated Annexin V-binding cells whereas forsterite and wollastonite induced an increase in the number of the apoptotic cells only at the concentration of 250 µg/mL. The LDH assay did not show statistically significant changes in the proliferation of MMSCs after treatment with the bioceramics at the tested concentrations when compared to control (p > 0.05). This finding showed that the death of a part of cells during the first 24 h of incubation did not prevent the proliferation of MMSCs incubated with diopside, forsterite and wollastonite for 72 h.