Decellularized xenogenic cartilage extracellular matrix (ECM) scaffolds for the reconstruction of osteochondral defects in rabbits.

The use of decellularized native allogenic or xenogenic cartilaginous extracellular matrix (ECM) biomaterials is widely expanding in the fields of tissue engineering and regenerative medicine. In this study, we aimed to develop an acellular, affordable, biodegradable, easily available goat conchal cartilaginous ECM derived scaffolding biomaterial for repair and regeneration of osteochondral defects in rabbits. Cartilages harvested from freshly collected goat ears were decellularized using chemical agents, namely, hypotonic-hypertonic (HH) buffer and Triton X-100 solution, separately. The morphologies and ultrastructure orientations of the decellularized cartilages remained unaltered in spite of complete cellular loss. Furthermore, when the acellular cartilaginous ECMs were cultured with murine mesenchymal stem cells (MSCs) (C3H10T1/2 cells), cellular infiltration and proliferation were thoroughly monitored using SEM, DAPI and FDA stained images, whereas the MTT assay proved the biocompatibility of the matrices. The increasing amounts of secreted ECM proteins (collagen and sGAG) indicated successful chondrogenic differentiation of the MSCs in the presence of the treated cartilage samples. In vivo biocompatibility studies showed no significant immune response or tissue rejection in the treated samples but tissue necrosis in control samples after 3 months. Upon implantation of the constructs in rabbits' osteochondral defects for 3 months, the histological and micro-CT evaluation revealed significant enhancement and regeneration of neocartilage and subchondral bony tissues. The IGF-1 loaded cartilaginous constructs showed comparatively better healing response after 3 months. Our results showed that decellularized xenogenic cartilaginous biomaterials preserved the bioactivity and integrity of the matrices that also favored in vitro stem cell proliferation and chondrogenic differentiation and enabled osteochondral regeneration, thus paving a new way for articular cartilage reconstruction.

Development and Characterization of Acellular Caprine Choncal Cartilage Matrix for Tissue Engineering Applications.

Because of poor regenerative capabilities of cartilage, reconstruction of similar rigidity and flexibility is difficult, challenging, and restricted. The aim of the present investigation was to develop cost-effective acellular xenogeneic biomaterial as cartilage substitution. Two novel biometrics have been developed using different chemical processes (Na-deoxycholate + SDS and GndHCl + NaOH) to decellularize caprine (goat) ear cartilage and further extensively characterized before preclinical investigation. Complete cell removal was ascertained by hematoxylin and eosin staining followed by DNA estimation. No adverse effect on extracellular matrix (ECM) was found by quantifying collagen and sulfated glycosaminoglycans (sGAG) content as well as collagen, sGAG and elastin staining. Results showed no drastic changes in ECM structure apart from desired sGAG loss. Scanning electron microscopy images confirmed cellular loss and unaltered orientation. Nano-indentation study on cartilage matrices indicated interesting output showing better results among decellularized groups. Increased elastic modulus and hardness indicated better stiffness and more active energy dissipation mechanism due to decellularization. Fluid uptake and retention property remained unchanged after decellularization as analyzed by swelling behavior study. Additionally, acellular materials were confirmed to be nonreactive and nonhemolytic as assessed by in vitro hemocompatibility study. In vivo study (up to 3 months) on rabbits showed no symptoms of graft rejection/ tissue necrosis, established through postoperative histology and biochemical analyses of tissue explants. With regard to size, shape, biomechanics, source of origin and nonimmunogenic properties, these developed materials can play versatile role in biomedical/ clinical applications and pave a new insight as alternatives in cartilage reconstruction.

Surface Modified Metallic Orthopedic Implant for Sustained Drug Release and Osteocompatibility.

Designing implants with good antibacterial activity and simultaneously providing a platform for osteoblast adhesion is a challenge for researchers. All metallic implants, currently in use, are biocompatible but bioinert. This may lead to a weak interface with the bone and cause asceptic loosening. The aim of the present study is designing an implant with good antibacterial activity and simultaneously providing a platform for osteoblast adhesion. This is achieved by surface engineering of the currently used metallic implants without affecting their mechanical properties. The FDA approved plasma spraying technique is utilized to synthesize interconnected microporous bioactive hydroxyapatite (HA) coating on the Ti-6Al-4 V implant surface. The modified implant surface is impregnated with drug (gentamicin) loaded biodegradable polymer (chitosan) through a customized vacuum impregnation process. During impregnation, drug loaded polymer filled the pores of coating while leaving the rest of the HA surface exposed to promote osteoconductivity. The hardness and elastic modulus of the HA coating showed insignificant changes after impregnation with the drug loaded polymer, while the fracture toughness is improved by ∼42%. In vitro drug release studies have revealed a sustained release up to 180 h, with an ideal initial burst release. The drug loaded surfaces have also shown very efficient antibacterial activity against S. aureus, even after 5 days of incubation. Further, the modified surfaces have shown excellent osteocompatibility, due to the presence of the exposed HA coated surface. Thus, the surface modified implants, with a unique combination of antibacterial activity, osteocompatibility, and improved fracture toughness, have promising potential applications in orthopedics.