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Title: Role of Nanog in the maintenance of marrow stromal stem cells during post natal bone regeneration

Highlights: Black-Right-Pointing-Pointer Nanog is related to marrow stromal stem cell maintenance. Black-Right-Pointing-Pointer Increasing Nanog expression is seen during post natal surgical bone repair. Black-Right-Pointing-Pointer Nanog knockdown decreases post surgical bone regeneration. -- Abstract: Post natal bone repair elicits a regenerative mechanism that restores the injured tissue to its pre-injury cellular composition and structure and is believed to recapitulate the embryological processes of bone formation. Prior studies showed that Nanog, a central epigenetic regulator associated with the maintenance of embryonic stem cells (ESC) was transiently expressed during fracture healing, Bais et al. . In this study, we show that murine bone marrow stromal cells (MSCs) before they are induced to undergo osteogenic differentiation express {approx}50 Multiplication-Sign the background levels of Nanog seen in murine embryonic fibroblasts (MEFs) and the W20-17 murine marrow stromal cell line stably expresses Nanog at {approx}80 Multiplication-Sign the MEF levels. Nanog expression in this cell line was inhibited by BMP7 treatment and Nanog lentivrial shRNA knockdown induced the expression of the terminal osteogenic gene osteocalcin. Lentivrial shRNA knockdown or lentiviral overexpression of Nanog in bone MSCs had inverse effects on proliferation, with knockdown decreasing and overexpression increasing MSC cell proliferation. Surgical marrow ablation of mouse tibia bymore » medullary reaming led to a {approx}3-fold increase in Nanog that preceded osteogenic differentiation during intramembranous bone formation. Lentiviral shRNA knockdown of Nanog after surgical ablation led to an initial overexpression of osteogenic gene expression with no initial effect on bone formation but during subsequent remodeling of the newly formed bone a {approx}50% decrease was seen in the expression of terminal osteogenic gene expression and a {approx}50% loss in trabecular bone mass. This loss of bone mass was accompanied by an increased {approx}2- to 5-fold adipogenic gene expression and observed increase of fat cells in the marrow space. In summary these data show that Nanog is expressed during surgically induced marrow bone formation and is functionally involved in post natal marrow stromal cell maintenance and differentiation.« less
Authors:
; ; ;  [1] ;  [2] ;  [1]
  1. Orthopaedic Research Laboratory, Department of Orthopedic Surgery, Boston University School of Medicine, Boston, MA 02118 (United States)
  2. Pulmonary Center, Boston University School of Medicine, Boston, MA 02118 (United States)
Publication Date:
OSTI Identifier:
22207623
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemical and Biophysical Research Communications; Journal Volume: 417; Journal Issue: 1; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ABLATION; BIOLOGICAL REPAIR; BONE MARROW; CELL PROLIFERATION; FAT CELLS; FIBROBLASTS; FRACTURES; HEALING; INJURIES; MICE; REGENERATION; STEM CELLS; SURGERY; TIBIA; TRABECULAR BONE