Mechanism-Driven Technology Development for Solving the Intracellular Delivery Problem of Hard-To-Transfect Cells

Abstract

The so-called “hard-to-transfect cells” are well-known to present great challenges to intracellular delivery, but detailed understandings of the delivery behaviors are lacking. Recently, we discovered that vesicle trapping is a likely bottleneck of delivery into a type of hard-to-transfect cells, namely, bone-marrow-derived mesenchymal stem cells (BMSCs). Driven by this insight, herein, we screened various vesicle trapping–reducing methods on BMSCs. Most of these methods failed in BMSCs, although they worked well in HeLa cells. In stark contrast, coating nanoparticles with a specific form of poly(disulfide) (called PDS1) nearly completely circumvented vesicle trapping in BMSCs, by direct cell membrane penetration mediated by thiol–disulfide exchange. Further, in BMSCs, PDS1-coated nanoparticles dramatically enhanced the transfection efficiency of plasmids of fluorescent proteins and substantially improved osteoblastic differentiation. In addition, mechanistic studies suggested that higher cholesterol content in plasma membranes of BMSCs might be a molecular-level reason for the greater difficulty of vesicle escape in BMSCs.

Direct Membrane Penetration and Cytosolic Delivery of Nanoparticles via Electrostatically Bound Amphiphiles

“…Nanoparticles are used in a variety of biomedical applications such as bioimaging probes, optical tracking of a single-molecule event, understanding subcellular processes, subcellular targeting/delivery, and theranostic agents. − In these applications, functional nanoparticles are commonly used, which are prepared via covalent linking of chemicals/biochemicals with the nanoparticles. Most of these functional nanoparticles are designed to interact with specific subcellular compartments/biomolecules for the actual performance .…”