Double Rolling Circle Amplification Generates Physically Cross-Linked DNA Network for Stem Cell Fishing

Stem cells have been widely studied in cell biology and utilized in cell-based therapies, and fishing stem cells from marrow is highly challenging due to the ultralow content. Herein, a physically cross-linked DNA network-based cell fishing strategy is reported, achieving efficient capture, 3D envelop, and enzyme-triggered release of bone marrow mesenchymal stem cells (BMSCs). DNA network is constructed via a double rolling circle amplification method and through the intertwining and self-assembly of two strands of ultralong DNA chains. DNA-chain-1 containing aptamer sequences ensures specific anchor with BMSCs from marrow. Hybridization between DNA-chain-1 and DNA-chain-2 enables the cross-link of cell-anchored DNA chains to form a 3D network, thus realizing cell envelop and separation. DNA network creates a favorable microenvironment for 3D cell culture, and remarkably the physically cross-linked DNA network shows no damage to cells. DNA network is digested by nuclease, realizing the deconstruction from DNA network to fragments, and achieving enzyme-triggered cell release; after release, the activity of cells is well maintained. The strategy provides a powerful and effective method for fishing stem cells from tens of thousands of nontarget cells.