Nanosecond Pulsed Electric Fields (nsPEFs) Enhanced Stem-ness of Mesenchymal Stem Cells
Prof. GE Zigang
Biomedical Engineering Center
Date & Time
Room 7-37, Haking Wong Building, HKU
Upregulation of differentiation potential of mesenchymal stem cells would contribute to the development of regenerative medicine. Over-expressing of stemness genes could promote the differentiation potential of MSCs. However, this technology has security problems and is limited in clinical application. To deal with this, we chose nanosecond pulsed electric fields (nsPEFs) with duration at the nanosecond level and field strength as high as kV/cm. It could affect intracellular organelles and trigger strong biological effects. nsPEFs is a novel physical technique in cancer therapy and has attracted rising attention in the field of stem cell differentiation. Here we aim to study the effects of nsPEFs on chondrogenic differentiation, osteogenic differentiation and adipogenic differentiation of MSCs in vitro and further to explore the mechanisms behind the phenomenon.
Cell viability was performed to evaluate the safety of nsPEFs-preconditioning on MSCs. The effects of nsPEFs-preconditioning on the expression levels of tri-lineage differentiation marker genes were evaluated by quantitative RT-PCR. Alcian blue staining, Alizarin Red S staining and Oil red O staining were performed to further evaluate the effects of nsPEFs-preconditioning on chondrogenic differentiation, osteogenic differentiation and adipogenic differentiation, respectively. Mechanisms were explored with gene expression level of OCT4 and Nanog. The methylation status of CpG sites of Oct4 and Nanog was checked by bisulfite sequencing. The expression of DNA methylation transferase, as well as the level of global DNA methylation level were performed to further study the mechanism behind.
nsPEFs-preconditioning with proper parameters (10 ns at 20 kV/cm, 100 ns at 10 kV/cm) significantly potentiated tri-lineage differentiation capacity of MSCs with upregulated genes expression. nsPEFs-preconditioning could promote the formation of glycosaminoglycan for chondrogenic differentiation, calcium nodule for osteogenic differentiation, lipid droplet for adipogenic differentiation through downregulation of DNMT1 and global DNA methylation level, followed by demethylation of OCT4 and Nanog and upregulation of OCT4 and Nanog.
This study creatively demonstrates a unique approach of nsPEFs-treatment to potentiate the tri-lineage differentiation potential of MSCs through demethylation of OCT4 and Nanog which have translational potential for MSCs-based regenerative medicine.
Dr. Ge Zigang, Professor, Biomedical Engineering Center, Peking University；Adjunct Professor, Center for Bone & Joint Disease, Peking University People's Hospital; Program Faculty of Georgia Institute of Technology. Dr. Ge Zigang graduated from Peking University School of Health Science and worked as an orthopaedic Surgeon in Beijing Jishuitan Hospital. Since 2000, he has studied at the National University of Singapore. He has received Master of Science and Doctor of Medicine degree and Singapore Millennium Scholarship in 2006. In 2007, he joined the Department of Biomedical Engineering under the "Outstanding Overseas Young Talents Introduction Program of College of Engineering, Peking University".
Dr. Ge Zigang's main contributions in the research of articular cartilage regeneration include: 1) developing a series of biomaterials for regenerative medicine; 2) deeply analyzing the mechanism of biophysical signals (nanosecond electric pulse) on stem cell differentiation and cartilage regeneration; 3) deepening the research of stem cell cartilage differentiation, and developing a series of biotechnologies, which promotes the development of cartilage regeneration medicine.