ABSTRACT
Osteochondral defects caused by degenerative diseases of joints, traumas and inflammation are important issues in clinical practice. Different types of autologous platelet concentrate (PCs) are used in bone and cartilage regeneration. The present study aimed to investigate the effect of lyophilized platelet-rich fibrin (L-PRF) on the repair of osteochondral defects in rabbits. L-PRF was first prepared from fresh PRF (F-PRF) through freeze-drying, and histological and microstructural observations were performed to compare the characteristics of L-PRF and F-PRF. Thereafter, these bioactive scaffolds were implanted into osteochondral defects surgically created in rabbits to assess their effects on tissue repair using micro-CT scanning, histological observations and the evaluation scoring method for cartilage repair established by the International Cartilage Repair Society (ICRS). L-PRF had a histological structure similar to F-PRF. At 16 weeks after implantation surgery, full-thickness osteochondral defects with a diameter of 5 mm and a depth of 4 mm were well-filled with newly regenerated tissues, exhibiting the simultaneous regeneration of avascular articular cartilage and well-vascularized subchondral bone, as proven through macroscopic and microscopic observations in PRF-treated groups compared with that in the untreated group. The application of L-PRF and F-PRF for osteochondral defects in rabbits contributed to massive host remodeling and reconstruction of osteochondral tissues, thus offering a prospective bioactive scaffold for the simultaneous reconstruction of articular cartilage and subchondral bone tissue.
ABSTRACT
Cell sheet technology has been widely used in bone tissue engineering and regenerative medicine. However, controlling the shape and volume of large pieces of engineered bone tissue remains impossible without additional suitable scaffolds. Three-dimensional (3D) printed titanium (Ti) alloy scaffolds are mostly used as implant materials for repairing bone defects, but the unsatisfactory bioactivities of traditional Ti-based scaffolds severely limit their clinical applications. Herein, we hypothesize that the combination of bone marrow mesenchymal stem cell (BMSC) sheet technology and 3D porous Ti-6Al-4V (PT) alloy scaffolds could be used to fabricate biomimetic engineered bone. First, various concentrations of BMSCs were directly cocultured with PT scaffolds to obtain complexes of osteoblastic cell sheets and scaffolds. Then, as an experimental control, an osteoblastic BMSC sheet was prepared by continuous culturing under osteogenic conditions for 2 weeks without passaging and used to wrap the scaffolds. The BMSC sheet was composed of several layers of extracellular matrix (ECM) and a mass of BMSCs. The BMSCs exhibited excellent adherent, proliferative and osteogenic potential when cocultured with PT scaffolds, which may be attributed to the ability of the 3D microstructure of scaffolds to facilitate the biological behaviors of cells, as confirmed by the in vitro results. Moreover, the presence of BMSCs and ECM increased the angiogenic potential of PT scaffolds by the secretion of VEGF. Micro-CT and histological analysis confirmed the in vivo formation of biomimetic engineered bone when the complex of cocultured BMSCs and PT scaffolds and the scaffolds wrapped by prepared BMSC sheets were implanted subcutaneously into nude mice. Therefore, the combination of BMSC sheet technology and 3D-printed PT scaffolds could be used to construct customized biomimetic engineered bone, offering a novel and promising strategy for the precise repair of bone defects.
ABSTRACT
Bioactive scaffolds from synthetical polymers or decellularized cartilage matrices have been widely used in osteochondral regeneration. However, the risks of potential immunological reactions and the inevitable donor morbidity of these scaffolds have limited their practical applications. To address these issues, a biological extracellular matrix (ECM) scaffold derived from allogenic decellularized bone marrow mesenchymal stem cell (BMSC) sheets was established for osteochondral reconstruction. BMSCs were induced to form cell sheets. Three different concentrations of sodium dodecyl sulfate (SDS), namely, 0.5%, 1%, and 3%, were used to decellularize these BMSC sheets to prepare the ECM. Histological and microstructural observations were performed in vitro and then the ECM scaffolds were implanted into osteochondral defects in rabbits to evaluate the repair effect in vivo. Treatment with 0.5% SDS not only efficiently removed BMSCs but also successfully preserved the original structure and bioactive components of the ECM When compared with the 1% and 3% SDS groups, histological observations substantiated the superior repair effect of osteochondral defects, including the simultaneous regeneration of well-vascularized subchondral bone and avascular articular cartilage integrated with native tissues in the 0.5% SDS group. Moreover, RT-PCR indicated that ECM scaffolds could promote the osteogenic differentiation potential of BMSCs under osteogenic conditions while increasing the chondrogenic differentiation potential of BMSCs under chondrogenic conditions. Allogenic BMSC sheets decellularized with 0.5% SDS treatment increased the recruitment of BMSCs and significantly improved the regeneration of osteochondral defects in rabbits, thus providing a prospective approach for both articular cartilage and subchondral bone reconstruction with cell-free transplantation.
