Direct Reprogramming of Human Suspension Cells into Mesodermal Cell Lineages via Combined Magnetic Targeting and Photothermal Stimulation by Magnetic Graphene Oxide Complexes

Suspension cells can provide a source of cells for cellular reprogramming, but they are difficult to transfect by nonviral vectors. An efficient and safe nonviral vector (GO-Fe₃O₄-PEI complexes) based on iron oxide nanoparticle (Fe₃O₄)-decorated graphene oxide (GO) complexed with polyethylenimine (PEI) for the first time is developed for delivering three individual episomal plasmids (pCXLE-hOCT3/4-shp53, pCXLE-hSK, and pCXLE-hUL) encoding pluripotent-related factors of Oct3/4, shRNA against p53, Sox2, Klf4, L-Myc, and Lin28 into human peripheral blood mononuclear cells (PBMCs) simultaneously. The combined treatment of magnetic stirring and near-infrared (NIR)-laser irradiation, which can promote contact between the complexes and floating cells and increase the cell membrane permeability, respectively, is used to conduct multiple physical stimulations for suspension PBMCs transfection. The PCR analysis shows that the combinatorial effect of magnetic targeting and photothermal stimulation obviously promoted the transfection efficiency of suspension cells. The transfected cells show positive expression of the pluripotency markers, including Nanog, Oct4, and Sox2, and have potential to differentiate into mesoderm and ectoderm cells. The results demonstrate that the GO-Fe₃O₄-PEI complex provides a safe, convenient, and efficient tool for reprogramming PBMCs into partially induced pluripotent stem cells, which are able to rapidly transdifferentiate into mesodermal lineages without full reprogramming.