Human Perivascular Stem Cell-Derived Extracellular Vesicles Mediate Bone
RESEARCH ARTICLE Human perivascular stem cell-derived extracellular vesicles mediate bone repair Jiajia Xu1, Yiyun Wang1, Ching-Yun Hsu1, Yongxing Gao1, Carolyn Ann Meyers1, Leslie Chang1, Leititia Zhang1,2, Kristen Broderick3, Catherine Ding4, Bruno Peault4,5,6, Kenneth Witwer7,8, Aaron Watkins James1* 1Department of Pathology, Johns Hopkins University, Baltimore, United States; 2Department of Oral and Maxillofacial Surgery, School of Stomatology, China Medical University, Shenyang, China; 3Department of Surgery, Johns Hopkins University, Baltimore, United States; 4Department of Orthopaedic Surgery, Orthopaedic Hospital Research Center, UCLA, Orthopaedic Hospital, Los Angeles, United States; 5Centre For Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom; 6MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, United Kingdom; 7Department of Molecular and Comparative Pathobiology, Johns Hopkins University, Baltimore, United States; 8Department of Neurology, Johns Hopkins University, Baltimore, United States Abstract The vascular wall is a source of progenitor cells that are able to induce skeletal repair, primarily by paracrine mechanisms. Here, the paracrine role of extracellular vesicles (EVs) in bone healing was investigated. First, purified human perivascular stem cells (PSCs) were observed to induce mitogenic, pro-migratory, and pro-osteogenic effects on osteoprogenitor cells while in non- contact co-culture via elaboration of EVs. PSC-derived EVs shared mitogenic, pro-migratory, and pro-osteogenic properties of their parent cell. PSC-EV effects were dependent on surface- associated tetraspanins, as demonstrated by EV trypsinization, or neutralizing antibodies for CD9 or CD81. Moreover, shRNA knockdown in recipient cells demonstrated requirement for the CD9/ CD81 binding partners IGSF8 and PTGFRN for EV bioactivity. Finally, PSC-EVs stimulated bone repair, and did so via stimulation of skeletal cell proliferation, migration, and osteodifferentiation.
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