A DNA micro-complex containing polyaptamer for exosome separation and wound healing

Exosomes (EXOs) have showed great potential in regenerative medicine. The separation of EXOs from complex biological media is essential for the down-stream applications. Herein, we report a deoxyribonucleic acid (DNA)-based micro-complex (DMC) containing polyaptamers, which realized the specific separation of EXOs from cell culture media and the significant promotion of wound healing. The synthesis of DMCs was based on a biomineralization process via rolling circle amplification (RCA) under the catalysis of phi29 DNA polymerase. To endow DMCs with the ability to capture EXOs, the DNA template of RCA was integrated with complementary sequence of aptamer that specifically recognized the CD63 proteins on EXOs. The obtained DMCs contained polyaptamers that can specifically capture the EXOs in cell culture media. The EXOs-capturing DMCs were collected by centrifugation, achieving the separation of EXOs. Mesenchymal stem cell (MSC)-derived EXOs (MSC-EXOs) were separated by this DMC-based strategy, and the separated MSC-EXOs significantly enhanced the migration ability of cells. In particular, the significant therapeutic efficacy of the DMCs with MSC-EXOs was verified in full-thickness wound excision mouse models, in which the wounds completely healed in 10 days. We envision that this DMC-based separation strategy can be a promising route to promote the development of EXOs in biomedicine.