Chitosan hydrogel reinforced with decellularized umbilical cord extracellular matrix and carbon nanotubes: a new trend for cartilage regeneration Mehrdad Omidi a , Arefeh Basiri b,* , Javad Mohammadnejad a,**, Saeed Karbasi b , Abbas shafiee c a Department of Interdisciplinary Science and Technologies, School of Life Science Engineering, Tehran University, Tehran, Iran b Department of Biomaterials, Nanotechnology and Tissue Engineering, School of Advanced Technologies in Medicine, Isfahan University of Medical Sciences, Isfahan, Iran c The University of Queensland Frazer Institute, Faculty of Health, Medicine and Behavioral Sciences, The University of Queensland, Brisbane, QLD, 4102, Australia A