Circular RNAs (circRNAs) are novel members of the noncoding RNA family. Their characteristic covalent closed-loop structure endows circRNAs that are much more stable than the corresponding linear transcript. circRNAs are ubiquitous in eukaryotic cells, and their functions are diverse and include adsorbing microRNAs (miRNAs; acting as miRNA sponges), regulating transcription, interacting with RNA-binding proteins, and translating and deriving pseudogenes. Moreover, circRNAs are associated with the occurrence and progression of a variety of cancers, acting as new biomarkers for early diagnosis to evaluate curative effects and patient prognosis. Here, this paper briefly describes the characteristics and functions of circRNAs, and it further concludes the relationship between circRNAs and human cancer.

Injectable thermo-sensitive hydrogels composed of small intestinal submucosa (SIS) with exosomes derived from bone marrow mesenchymal stem cells (BMSCs) are desired for bone regeneration. However, poor mechanical properties limit the clinical application of SIS hydrogels. Herein, the mechanical properties of SIS hydrogels incorporated with 3-(3,4-dihydroxyphenyl) propionic acid (CA) are assessed. The results show that the mechanical properties of SIS hydrogels are improved. In addition, the retention and stability of exosomes over time at the defect site are also challenges. Fusion peptides are designed by connecting collagen-binding domines (CBDs) of collagen type I/III with exosomal capture peptides CP05 (CRHSQMTVTSRL) directly or via rigid linkers (EAAAK). In vitro experiments demonstrate that fusion peptides are contribute to promoting the positive effect of exosomes on osteogenic differentiation of BMSCs. Meanwhile, the results of hydrogels combining exosomes and fusion peptides in the treatment of rat skull defect models reveal that fusion peptides could enhance the retention and stability of exosomes, thereby strengthen the therapeutic effect for skull defects. Therefore, SIS hydrogels with CA modified by fusion peptides and exosomes appear to be a promising strategy in bone regenerative medicine.