Stem Cells from the Apical Papilla-Laden Microgels in Combination with Mandibular Advancement for Adult Condylar Cartilage Development.

Angle's Class II malocclusion, characterized by mandibular retraction, significantly impacts occlusal function and facial aesthetics. In adults, the limited development potential of the condylar cartilage poses challenges to effective mandibular remodeling. Clinically, mandibular advancement (MA) can promote the development of condylar cartilage in adolescents, but its effect on adult condylar cartilage remains controversial. Herein, MA is achieved via three methods in adult rats to investigate the effect of MA on adult condylar cartilage development. MA could stimulate the growth of adult condylar cartilage. Nevertheless, the rate of condylar cartilage development remains slow, as evidenced by a maximum cartilage thickness increase of 7.7%. To further promote condylar cartilage development, stem cells from the apical papilla (SCAPs)-laden microgels are fabricated via droplet microfluidic technology. Microgels with reduced stiffness and accelerated stress relaxation significantly promote the proliferation and chondrogenic differentiation of SCAPs. Animal experiments have demonstrated that SCAPs-laden microgels combined with MA significantly accelerate the development of condylar cartilage, with a 15% increase in condylar cartilage thickness and upregulated expressions of Col I, Col II, and SOX9 compared to that in the MA group. This study demonstrates that SCAPs-laden microgels in combination with MA can enhance cartilage development, which will advance the adult mandibular remodeling technologies.