Smart Materials for Cartilage and Bone Tissue Engineering

Abstract

Osteoarthritis (OA) is a chronic disease normally caused by trauma or pathological disorder. Its symptom normally starts from the degeneration of cartilage, resulting in an irregular tough surface, and might progressively extend to subchondral bone, leading to the abnormal joint function and disability. Due to the avascular and condensed structure of cartilage, and the limited number of progenitor cells, it is challenging for regeneration of cartilage defects. Furthermore, because of the distinct structure of cartilage and subchondral bone, stem cell-alone or biomaterial-alone based strategy might not be able to simultaneously fulfil the requirement for regeneration of cartilage and subchondral bone. Hence, in this thesis, a variety of smart materials, such as thermosensitive poly (N-isopropylacrylamide-acrylic acid) hydrogel and magnetic field-responsive scaffold, were fabricated, characterized, and utilized for three-dimensional (3D) culture of mesenchymal stem/stromal cells (MSCs) in vitro. It was found that MSCs showed quite good cell viability and these smart materials promoted the capacity of multi-lineage differentiation due to either functional enhancement of cell aggregates in the thermosensitive hydrogels or synergy of a dynamic magnetic field, mechanical stimulation, structural topography, dynamic culture, extracellular matrix (ECM)-mimicking materials, and inductive biomolecules in the magnetic field-responsive scaffolds. When allogeneic MSC aggregates were delivered in vivo by the thermosensitive hydrogel, osteochondral defects were fully regenerated, which demonstrated that the thermosensitive hydrogel might be a promised vehicle for the delivery of stem cells and facilitate the osteochondral regeneration. Moreover, those autologous chondrogenesis-induced MSCs either in the thermosensitive hydrogel or in the magnetic field-responsive scaffolds were also able to be engineered into a neo-cartilage patch or tissue, respectively, which might also have potential application in cartilage and bone regeneration. In conclusion, the fabricated smart materials including a thermosensitive hydrogel and a magnetic field-responsive scaffold, may assist in stem cell therapy for promising efficacy of OA treatment.