In Vivo Evaluation of miRNA-Loaded Scaffold for Stem Cell-Mediated Bone Regeneration

After the controlled miRNA release scaffold system was established, scaffolds immobilized with 64 or 6.5 k PLGA MS containing miR-26a/polymer, NC/polymer polyplexes or with blank MS were seeded with 1 × 10⁵ mouse mesenchymal stem cells and implanted in subcutaneous pockets on the back of nude mice as described in ref. 65 (link). Briefly, 6–8-week-old male nude mice (Charles River Laboratories) were anaesthetized with 2% inhalation of isofluorane. Two dorsal midsagittal incisions were made on the disinfected back. One subcutaneous pocket was created on each side of each incision using blunt dissection, and one scaffold was implanted into each pocket. Four samples were implanted randomly for each group (n=5). For transfection efficiency and miRNA expression detection, mice were killed and the implants were harvested at 2 weeks. For bone-formation examination, the implants were harvested at 8 weeks for subsequent microCT analysis. The animal procedure was approved by the University of Michigan Committee on Use and Care of Laboratory Animals.