Cartilage tissue engineering is the interdisciplinary science that will help to improve cartilage afflictions, such as arthrosis, arthritis, or following joints traumatic injuries.In the present work, we developed an injectable hydrogel which derived from decellularized extracellular matrix of sheep cartilage. Successful decellularization was evaluated by measuring the DNA, glycosaminoglycans (GAG), collagen contents, and histological analyses. There was a minor difference in GAG and collagen contents among natural cartilage and decellularized tissue as well as ultimate hydrogel. Rheological analysis showed that the temperature and gelation time of prepared hydrogel were 37 C and between 5 and 7 min, respectively. Mechanical properties evaluation indicated a storage modulus of 20 kPa. The results show that prepared hydrogel possessed cell-friendly microenvironment as confirmed via calcein staining and MTT assay. Also, cells were able to proliferate which observed by H&E and alcian blue staining. Cell attachment and proliferation at the surface of the decellularized hydrogel was apparent by Scanning Electron Microscope (SEM) images and microphotographs. Furthermore, the cells embedded within the hydrogel were able to differentiate into chondrocyte with limited evidence of hypertrophy and osteogenesis in utilized cells which proved by SOX9, CoL2, ACAN, and also CoL1 and CoL10 gene expression levels. In summary, the results suggest that developed novel injectable hydrogel from decellularized cartilage could be utilized as a promising substrate for cartilage tissue engineering applications. K E Y W O R D Sbiocompatible, cartilage, decellularized ECM, injectable hydrogel, mesenchymal stem cell

Tissue engineering is one of the most promising areas for treatment of various ophthalmic diseases particularly for patients who suffer from limbal stem cell deficiency and this is due to the lack of existence of appropriate matrix for stem cell regeneration. The aim of this research project is to design and fabricate triple layered electrospun nanofibers as a suitable corneal tissue engineering scaffold and the objective is to investigate and perform various in vitro tests to find the most optimum and suitable scaffold for this purpose. Electrospun scaffolds were prepared in three layers. Poly(D, L-lactide-co-glycolide; PLGA, 50:50) nanofibers were electrospun as outer and inner layers of the scaffold and aligned type I collagen nanofibers were electrospun in the middle layer. Furthermore, the scaffolds were cross-linked by 1-ethyl-3-(3 dimethylaminopropyl) carbodiimide hydrochloride and glutaraldehyde.Structural, physical, and mechanical properties of scaffolds were investigated by using N 2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, contact angle measurement, tensile test, degradation, shrinkage analysis, and scanning electron microscopy (SEM). In addition, capability to support cell attachment and viability were characterized by SEM, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and 4 0 ,6-diamidino-2-phenylindole staining. According to the result of Brunauer-Emmett-Teller analysis, specific surface area of electrospun scaffold was about 23.7 m 2 g -1 . Tensile tests on cross-linked scaffolds represented more

A major problem in the treatment of large bone defects is the inability to provide an adequate blood supply to the implantation site. Therefore, a bone regeneration strategy that provides an adequate supply of vessels would address this need. Cobalt (Co2+), because of its ability to induce hypoxia, has been used to accelerate new vessel formation. In this study, we used a freeze-drying technique to fabricate a scaffold that consisted of Co2+-doped calcium phosphate (CaP) [e.g., hydroxyapatite (HA)] and natural silk fiber through an optimized alternate mineralization process. The composition and structure of the scaffold were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), inductively coupled plasma (ICP), and scanning electron microscope (SEM). The data showed that the scaffolds promoted differentiation of adipose-derived mesenchymal stem cells (ADSCs) toward endothelial and osteoblast linages. We observed improved angiogenesis and bone formation with the fabricated scaffolds compared with the control groups. Computed tomography (CT) scans and radiographic imaging, in addition to histology and immunohistochemical analyses, showed the presence of angiogenesis and bone regeneration after implantation of the ADSC-seeded scaffolds in a critical size calavarial bone defect in a Wistar rat model. We obtained the best in vitro and in vivo results by doping 2% Co2+ in HA. Taken together, we propose that the Co2+-doped HA/silk fibroin (SF) scaffold would be a good candidate to induce angiogenesis and bone formation both in vitro and in vivo.

The hydrogel efficacy of taurine-loaded chitosan nanoparticle/alginate hydrogel was investigated for controlled release of the taurine substrate, which is known as an antioxidative drug. The composition of the fabricated hydrogels was explored by Fouriertransform infrared spectroscopy. The swelling ability and degradation rate of hydrogels were also analyzed in phosphate-buffered saline at the physiological condition and alginate lyase for a period of 21 days. Moreover, morphologies and structure of hydrogels and cells were determined using a scanning electron microscope. The possible cytotoxicity of the fabricated hydrogel was carried out by seeding endometrial stem cells on hydrogels. The results demonstrated that hydrogel of chitosan nanoparticle/alginate hydrogel successfully controlled the release of taurine. We observed that the chitosan nanoparticle/alginate hydrogel possessed adjust swelling ability and degradation rate as compared to neat alginate hydrogel. The results proved that the chitosan nanoparticle/alginate hydrogel is non-cytotoxic and could be utilized as a promising composition in tissue engineering and drug delivery systems.