Drug-Loaded Nanoparticles Induce Gene Expression in Human Pluripotent Stem Cell Derivatives

Tissue engineering and advanced manufacturing of human stem cells requires a suite of tools to control gene expression spatiotemporally in culture. Inducible gene expression systems offer cell-extrinsic control, typically through addition of small molecules, but small molecule inducers typically contain few functional groups for further chemical modification. Doxycycline (DXC) is a potent small molecule inducer of tetracycline (Tet) transgene systems. To gain additional functional handles on drug release and thus gene expression, here we report the conjugation of DXC to a hyperbranched biodegradable and biocompatible polymer nanoparticles (e.g., Boltorn H40). The hyperbranched polymer nanoparticle core offers a large number of peripheral functional groups which can be used to conjugate a large number of DXC molecules as well as polyethylene glycol (PEG) arms, thereby making the drug-polymer conjugate water soluble. The resulting nanoparticle (e.g., PEG–H40–DXC) exhibited pH-sensitive drug release behavior and successfully controlled gene expression in stem-cell-derived fibroblasts with a Tet-On system. While free DXC inhibited fibroblast proliferation and matrix metalloproteinase (MMP) activity, the nanoparticles maintained higher fibroblast proliferation levels and MMP activity. The results demonstrate that the DXC-nanoparticle system provides an effective tool to controlling gene expression in human stem cell derivatives. Further work with these nanoparticle systems could produce patterned hPSC-derived cell cultures, offering researchers the ability to investigate these cells in environments that optimally recapitulate complexities found within developing and diseased human tissues.