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A fibrous scaffold made of alginate or alginate/chitosan was fabricated for annulus fibrosus (AF) cell culture using a wet-spinning and lyophilization technique. The scaffolds were evaluated using several in vitro tests. Scanning electron microscopy showed the scaffold fibers generally aligned in one direction with individual fiber diameters varying between 40–100 μm. The alginate/chitosan hybrid scaffold exhibited a slower degradation rate, while both scaffold types did not display any cyto-toxicity to 3T3 fibroblasts and could maintain canine AF cell growth. The AF cells retained their spherical shape within the fibrous scaffold at the beginning of the culture period and formed into cell clusters at later times. Specific extracellular matrix molecules, including collagen I, collagen II, and aggrecan, could be detected in the AF cell clusters. These results demonstrate the feasibility of using this hybrid alginate/chitosan scaffold for AF cell culture, and the potential application for intervertebral disc tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007

In order to evaluate the repair potential in large osteochondral defects on high load-bearing sites, a hybrid scaffold system was made of three-dimensional porous Polycaprolactone (PCL) scaffold for the cartilage and tricalcium phosphate-reinforced PCL for the bone portion. Osteochondral defects of 4-mm diameter x 5.5-mm depth were created in the medial femoral condyle of adult New Zealand White rabbits. The defects were treated with hybrid scaffolds without cells (control group) or seeded with allogenic bone marrow-derived mesenchymal stem cells (BMSC) in each part (experimental group) by press-fit implantation. Implanted cells were tracked using Adeno-LacZ labeling. Repair tissues were evaluated at 3 and 6 months after implantation. Overall, the experimental group showed superior repair results as compared to the control group using gross examination, qualitative and quantitative histology, and biomechanical assessment. With BMSC implantation, the hybrid scaffolds provided sufficient support to new osteochondral tissues formation. The bone regeneration was consistently good from 3 to 6 months with firm integration to the host tissue. Cartilage layer resurfacing was more complicated. All of the samples showed cartilage tissues mixed with PCL scaffold filaments at 3 months. Histology at 6 months revealed some degradation phenomenon in several samples whereas others had a good appearance; however, the Young's moduli from the experimental group (0.72 MPa) approached that of normal cartilage (0.81 MPa). In vivo viability of implanted cells was demonstrated by the retention for 6 weeks in the scaffolds. This investigation showed that PCL-based hybrid scaffolds with BMSC may be an alternative treatment for large osteochondral defects in high-loading sites.