Evaluation of photopolymerizable hydrogel/stem cell constructs in vivo for cartilage tissue engineering

The use of 3-dimensional (3D) scaffolds combined with chondrogenic cells and chondroinductive factors has been the classic approach in cartilage tissue engineering. As the availability of chondrogenic cell source may face limitation, stem cells provide an alternative choice of cells for the regeneration of new cartilage tissue. The aim of this study was to investigate the feasibility of tissue-engineered constructs composed of photopolymerizable hydrogels and amniotic fluid-derived stem cells in the repair of articular cartilage defects in rabbit model. A mixture of poly(ethylene glycol) diacrylate (PEGDA), agarose and amniotic fluid-derived stem cells line T4 (AFT4) were rendered crosslinked by UV irradiation into a disc shape in a single-step preparation. Mechanical testing showed that the mixed PEGDA-agarose hydrogels could resist compressive loading better than hydrogels composed of PEGDA or agarose alone, and the viability of encapsulated cells in the mixed hydrogel constructs was about 60%. After the constructs were implanted into the full thickness cartilage defects, gross examination at week 12 showed that the new cartilage tissue covered most of the defects' surface area similar to control. Therefore, this study has demonstrated that hydrogel constructs composed PEGDA, agarose, and stem cells can be processed by photopolymerization, and preliminary results in vivo have shown that the constructs are biocompatible and possess the potential to be used in cartilage tissue engineering.