PRODUCTION OF MULTIPHASE OSTEOCHONDRAL SCAFFOLD BY USING BACTERIAL CELLULOSE-BASED COMPOSITES WITH ORIENTED FIBER STRUCTURE
Project no. 21947 · Status: Kapanmış (Yayın bekleniyor) · 2020
Summary
<p>The osteochondral defect is an increasingly common problem in the articular cartilage and underlying bone tissue caused by trauma, old age and osteoarthritis. It is still not fully treated in orthopaedic surgery. Current clinical treatment methods for the repair of osteochondral defects</p><p>offer temporary solutions. Tissue engineering applications offer alternatives for good repair of osteochondral defects and long-term durability of the treatment. It is essential to design scaffolds to successfully repair osteochondral defects, which can mimic the microenvironment of cartilage, calcified cartilage and bone interface in tissue scaffolds. The surface, middle, deep and calcified cartilage layers of osteochondral tissue have different extracellular matrix and nanofiber arrangements and, therefore, different mechanical properties and cell morphologies.</p><p><br></p><p>This thesis aims to produce a multiphase cell-free osteochondral scaffold with different nanofiber orientations in which different physical and chemical modifications mimic the microenvironment of bone and cartilage.</p><p><br></p><p>In our studies, bacterial cellulose (BS) synthesized by <em>Gluconacetobacter xylinus</em> was disintegrated for scaffolds with complex nanofiber structures and membrane BS was used for scaffolds with parallel and perpendicular structures to the surface. The complex nanofiber structure of the membrane BS was ensured to be below 30 ̊ with a nanofiber orientation of 73.4% by using an apparatus we developed. After optimizing sodium periodate oxidation for biodegradability, approximately 9% degradation was obtained at the end of 45 days with 0.05 M sodium periodate and 30 min oxidation time. It was determined that the pore diameter of the scaffolds prepared with shredded BS and modified with chitosan for cartilage was 100-150 μm, and the pore diameter of the scaffolds modified with HAp for bone was between 160-285 μm. The characterization tests of scaffolds modified with chitosan (0.1-0.5%) and glycosaminoglycan (GAG) (10%) for cartilage layer, hydroxyapatite and boron (0.01-0.05%) for bone layer, and chitosan, GAG, and calcium chloride for calcified cartilage layer were confirmed using Scanning Electron Microscopy, Energy Dispersive Spectrometry, Fourier Transform Infrared Spectroscopy, and X-Ray Photoelectron Spectroscopy. Additionally, Dimethylmethylene Blue Test (DMMB) staining was performed for the quantitative determination of GAG content in cartilage and calcified cartilage tissue scaffolds and Alkaline Phosphatase testing and Alizarin Red S staining for HAp in bone tissue scaffolds.</p><p><br></p><p>Then, as a result of cell viability and cell differentiation studies, it was determined that BS-Kitosan0.5-GAG for cartilage and BS-HAp-B0.01 for bone gave the best results. Static compression test results of the layers that will form the osteochondral structure; It was determined as 293 kPa</p><p>for BS-HAp-B0.01, 260 kPa for BS-Chitosan0.5-GAG, and 855 kPa for calcified cartilage. The peel test result on tissue scaffolds consisting of membrane and shredded BS layers was 41.04 mPa. As a result, a BS-based five-layer cell-free tissue scaffold was produced, in which the bone and cartilage microenvironment was simulated with physical and chemical modifications. As a result, a BS-based five-layer cell-free tissue scaffold was produced in which the layers and nanofiber orientations in osteochondral tissue were mimicked to differentiate cells in the tissue.</p>