title: Lipid Coated Microbubbles and Low Intensity Pulsed Ultrasound Enhance Chondrogenesis of Human Mesenchymal Stem Cells in 3D Printed Scaffolds.
abstract: Lipid-coated microbubbles are used to enhance ultrasound imaging and drug delivery. Here we apply these microbubbles along with low intensity pulsed ultrasound (LIPUS) for the first time to enhance proliferation and chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in a 3D printed poly-(ethylene glycol)-diacrylate (PEG-DA) hydrogel scaffold. The hMSC proliferation increased up to 40% after 5 days of culture in the presence of 0.5% (v/v) microbubbles and LIPUS in contrast to 18% with LIPUS alone. We systematically varied the acoustic excitation parameters-excitation intensity, frequency and duty cycle-to find 30 mW/cm2, 1.5 MHz and 20% duty cycle to be optimal for hMSC proliferation. A 3-week chondrogenic differentiation results demonstrated that combining LIPUS with microbubbles enhanced glycosaminoglycan (GAG) production by 17% (5% with LIPUS alone), and type II collagen production by 78% (44% by LIPUS alone). Therefore, integrating LIPUS and microbubbles appears to be a promising strategy for enhanced hMSC growth and chondrogenic differentiation, which are critical components for cartilage regeneration. The results offer possibilities of novel applications of microbubbles, already clinically approved for contrast enhanced ultrasound imaging, in tissue engineering.
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, 20052, USA.
authors.forename: Mitra
authors.initials: M
authors.lastname: Aliabouzar
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, 20052, USA.|Department of Biomedical Engineering, The George Washington University, Washington, DC, 20052, USA.|Department of Medicine, The George Washington University, Washington, DC, 20052, USA.
authors.forename: Lijie Grace
authors.initials: LG
authors.lastname: Zhang
authors.affiliation: Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, 20052, USA.
authors.forename: Kausik
authors.initials: K
authors.lastname: Sarkar
mesh_terms: D002356:Cartilage / Q000378:metabolism / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism / Q000502:physiology; D020219:Chondrogenesis / Q000502:physiology*; D024043:Collagen Type II / Q000378:metabolism; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D045423:Microbubbles; D010012:Osteogenesis / Q000502:physiology; D011092:Polyethylene Glycols / Q000737:chemistry; D066330:Printing, Three-Dimensional; D012038:Regeneration / Q000502:physiology; D023822:Tissue Engineering / Q000379:methods; D054457:Tissue Scaffolds; D000069453:Ultrasonic Waves; D014463:Ultrasonography / Q000379:methods
chemical_list: D024043:Collagen Type II; D008055:Lipids; C437167:poly(ethylene glycol)diacrylate; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols