Biological responses of ceramic bone spacers produced by green processing of additively manufactured thin meshes

Bone spacers are exclusively used for replacing the tissue after trauma and/or diseases. Ceramic materials bring positive opportunities to enhance greater osteointegration and performance of implants, yet processing of porous geometries can be challenging. Additive Manufacturing (AM) opens opportunities to grade porosity levels in a part; however, its productivity may be low due to its batch processing approach. The paper studies the biological responses yielded by hydroxyapatite with ß-TCP (tricalcium phosphate) ceramic porous bone spacers manufactured by robocasting 2-layer meshes that are rolled in green and sintered. The implants are assessed in vitro and in vivo for their compatibility. Human bone marrow mesenchymal stem cells attached, proliferated and differentiated on the bone spacers produced. Cells on the spacers presented alkaline phosphatase staining, confirming osteogenic differentiation. They also expressed bone-specific COL1A1, BGAP, BSP, and SPP1 genes. The fold change of these genes ranged between 8 to 16 folds compared to controls. When implanted into the subcutaneous tissue of rabbits, they triggered collagen fibre formation and mild fibroblastic proliferation. In conclusion, rolled AM-meshes bone spacers stimulated bone formation in vitro and were biocompatible in vivo. This technology may give the advantage to custom produce spacers at high production rates if industrially upscaled.Postprint (published version

Thioredoxin System and miR-21, miR-23a/b and let-7a as Potential Biomarkers for Brain Tumor Progression: Preliminary Case Data

Background: The thioredoxin system and microRNAs (miRNAs) are potential targets for both cancer progression and treatment. However, the role of miRNAs and their relation with the expression profile of thioredoxin system in brain tumor progression remains unclear. Methods: In this study, we aimed to determine the expression profiles of redox components Trx-1, TrxR-1 and PRDX-1, and oncogenic miR-21, miR-23a/b and let-7a and oncosuppressor miR-125 in different brain tumor tissues and their association with increasing tumor grade. We studied Trx-1, TrxR-1, and PRDX-1 messenger RNA expression levels by quantitative real-time polymerase chain reaction and protein levels by Western blot and miR-23a, miR-23b, miR-125a, miR-21, and let-7a miRNA expression levels by quantitative real-time polymerase chain reaction in 16 glioma, 15 meningioma, 5 metastatic, and 2 benign tumor samples. We also examined Trx-1, TrxR-1, and PRDX-1 protein levels in serum samples of 36 patients with brain tumor and 37 healthy volunteers by enzyme-linked immunosorbent assay. Results: We found that Trx-1, TrxR-1, and PRDX-1 presented high messenger RNA expression but low protein expression in low-grade brain tumor tissues, whereas they showed higher protein expression in sera of patients with low-grade brain tumors. miR-23b, miR-21, miR-23a, and let-7a were highly expressed in low-grade brain tumor tissues and positively correlated with the increase in thioredoxin system activity. Conclusions: Our findings showed that Trx-1, TrxR-1, miR-21, miR-23a/b, and let-7a might be used for brain tumor diagnosis in the clinic. Further prospective studies including molecular pathway analyses are required to validate the miRNA/Trx system regulatory axis in brain tumor progression. © 2022 Elsevier Inc

Kemik ve kıkırdak dokusu onarımına yönelik olarak yağ dokusundan farklılandırılmış hücre ve seramik/polimer kompozit içeren yapay dokuların geliştirilmesi

TÜBİTAK MAG01.05.200

Assessment of mineral density and atomic content of fracture callus by quantitative computerized tomography

The mineral density and atomic numbers of elements in the periosteal callus and the cortex area of a healing fracture were measured by quantitative computerized tomography (QCT) to obtain accurate information on the mineralization process in rabbit tibia. The mineral density of the periosteal callus was highest on day 15 and decreased gradually throughout the experiment. This was initially detected by QCT, but not with conventional radiography. An apparent decrease in cortical bone density on days 28 and 42 after fracture was observed. Atomic numbers of elements in the cortex remained stable, indicating a possible homeostatic mechanism of mineral preservation at the fracture callus and involved cortical area. QCT may predict density alterations in the fracture callus more accurately than conventional X-ray. Further studies are essential to predict a relationship between mineral density, atomic numbers, and mechanical stability

Vancomycin Containing Plla/Β-Tcp Controls Experimental Osteomyelitis In Vivo

Background Implant-related osteomyelitis (IRO) is recently controlled with local antibiotic delivery systems to overcome conventional therapy disadvantages. In vivo evaluation of such systems is however too little. Questions/purposes We asked whether vancomycin (V)-containing poly-l-lactic acid/β-tricalcium phosphate (PLLA/β-TCP) composites control experimental IRO and promote bone healing in vivo. Methods Fifty-six rats were distributed to five groups in this longitudinal controlled study. Experimental IRO was established at tibiae by injecting methicillin-resistant Staphylococcus aureus (MRSA) suspensions with titanium particles in 32 rats. Vancomycin-free PLLA/β-TCP composites were implanted into the normal and infected tibiae, whereas V-PLLA/β-TCP composites and coated (C)-V-PLLA/β-TCP composites were implanted into IRO sites. Sham-operated tibiae established the control group. Radiological and histological scores were quantified with microbiological findings on weeks 1 and 6. Results IRO is resolved in the CV- and the V-PLLA/β-TCP groups but not in the PLLA/β-TCP group. MRSA was not isolated in the CV- and the V-PLLA/β-TCP groups at all times whereas the bacteria were present in the PLLA/β-TCP group. Radiological signs secondary to infection are improved from 10.9 ± 0.9 to 3.0 ± 0.3 in the V-PLLA/β-TCP group but remained constant in the PLLA/β-TCP group. Histology scores are improved from 24.7 ± 6.5 to 17.6 ± 4.8 and from 27.6 ± 7.9 to 32.4 ± 8.9 in the CV-PLLA/β-TCP and the V-PLLA/β-TCP groups, respectively. New bone was formed in all the PLLA/β-TCP group at weeks 1 and 6. Conclusions CV- and V-PLLA/β-TCP composites controlled experimental IRO and promoted bone healing. Clinical relevance CV- and V-PLLA/β-TCP composites have the potential of controlling experimental IRO and promoting bone healing.PubMedWoSScopu

Quantification of Anandamide and 2-Arachidonylglycerol in Plasma Samples: A Short, Non-toxic HPLC Method and Sample Storage

Objective: The endocannabinoid system plays an important modulatory role in brain physiology, pain sensation, appetite regulation, cardiovascular system, female reproductive system and the immune system. The endogenous ligands of cannabinoid receptors, anandamide (ANA) and 2-Arachidonylglycerol (2-AG) have been identified in various mammalian tissues. However, it difficult to quantify them accurately in blood and in tissues since these endogenous cannabinoids are found in small amount and they are metabolized very quickly. In order to quantify ANA and 2-AG from blood accurately, it was aimed (a) to determine pre-analytical conditions in blood sampling procedure, (b) to improve extraction process and quantification of ANA and 2-AG in plasma samples by HPLC, and (c) to determine storage conditions and period of these metabolites

Mesenchymal Stem Cells and Nano-Bioceramics for Bone Regeneration

Orthopedic disorders and trauma usually result in bone loss. Bone grafts are widely used to replace this tissue. Bone grafts excluding autografts unfortunately have disadvantages like evoking immune response, contamination and rejection. Autografts are of limited sources and optimum biomaterials that can replace bone have been searched for several decades. Bioceramics, which have the similar inorganic structure of natural bone, are widely used to regenerate bone or coat metallic implants. As people continuously look for a higher life quality, there are developments in technology almost everyday to meet their expectations. Nanotechnology is one of such technologies and it attracts everyone's attention in biomaterial science. Nano scale biomaterials have many advantages like larger surface area and higher biocompatibility and these properties make them more preferable than micro scale. Also, stem cells are used for bone regeneration besides nano-bioceramics due to their differentiation characteristics. This review covers current research on nano-bioceramics and mesenchymal stem cells and their role in bone regeneration

Collagen-chondroitin sulfate-based PLLA-SAIB-coated rhBMP-2 delivery system for bone repair

Bone morphogenetic proteins (BMPs) are osteoinductive proteins used intensively in clinical investigations involving various bone-related treatments. Owing to their high potential in new bone formation they require local application at the treatment site. For this purpose various controlled delivery systems with BMPs as the excipients have been prepared in recent years. Focusing on this clinical need a disc-shaped BMP carrier was designed as a local delivery system using soluble collagen and chondroitin sulfate. In situ release studies carried out with a model protein (FITC-labeled Protein A) presented a very high rate of release; with most of the protein content being released within 24h. This rate could be decreased by providing a poly(L-lactide) (PLLA) and sucrose acetate isobutyrate-based (SAIB-based) coat around the release system, applied after BMP loading. In this way, it was possible to extend the release period from 24 h to about 12 days. In situ release of BMP from the same carriers, as quantitated using an ELISA kit, was even slower, with 50% of the protein being released in 15 days

Mikroküre formunda polimerik ilaç taşıyıcı

Polikaprolakton mikroküreler içerisine Doksisiklin ve kondroitin sülfat hapsedilmesi ile geliştirilmiş bu formülasyon 1) matriks metalloproteinaz enzimlerini engelleyici etkisi olan Doksisiklinin (D) ve kıkırdak onarımında rejeneratif etkisi olan kondroitin sülfat (CS) molekülünün bidikte mikrokürelere hapsedilmiş olması 2) doksisiklin şalımının kontrollü ve uzun süreçte olması (3 ayda %37 ilaç salımı), 3) ilaç hapsetme verimliliğinin %30 olması 4) eklem içi uygulamaları için istenilen boyutlarda, enjekte edilebilir olması, 4) Mikroküre içerisine yüklenen ilacın salınma sonrası MMP inhibisyon etkinliğini koruyor olması 5) in vivo artrit modeli üzerinde geliştirilen formülasyonun tedavi etkinliğinin gösterilmiş olması unsurlarını içerir

Osteoporotik sıçan dokularında iskelet kası atrofisinin immünohistoloji ve moleküler biyoloji yöntemleriyle araştırılması

TÜBİTAK SBAG01.04.201