Delivering siRNA to control osteogenic differentiation and real-time detection of cell differentiation in human mesenchymal stem cells using multifunctional gold nanoparticles.

Controlling and detecting cell differentiation in human mesenchymal stem cells (hMSCs) for regenerative medicine remain challenging at present. Here, we developed multifunctional gold nanoparticles (AuNPs) to control and detect osteogenic differentiation in human mesenchymal stem cells (hMSCs) in real-time. The polyethyleneimine (PEI) capped AuNPs (Au-PEI) were synthesized first and were then conjugated with a matrix metalloproteinase 13 (MMP13)-sensitive peptide-FITC group (EGPLGVRGKG-FITC) to obtain multifunctional AuNPs (AuNP-PEI-peptide-FITC). AuNP-PEI-peptide-FITC could bind siRNA with PEI by electrostatic interactions to form the AuNP-PEI-peptide-FITC/siRNA nanocomplexes, allowing efficient siRNA delivery in hMSCs. The adipogenic-related gene peroxisome proliferator-activated receptor γ (PPARγ) was targeted for silencing by the AuNP-PEI-peptide-FITC/siRNA nanocomplexes to control osteogenic differentiation in hMSCs. After demonstrating that the AuNP nanocomplexes could control cell differentiation, the versatility of this tool was illustrated by showing that it can be used as a nanoprobe for real time detection of the osteogenic differentiation of hMSCs. This was done by measuring the activity of the MMP13 enzyme (produced during osteogenic differentiation) through the recovery of FITC fluorescence. This multifunctional AuNP showed a robust new methodology for controlling cell fate and simultaneously detecting cell differentiation in real-time for hMSCs, which is promising for multiple applications in regenerative medicine.