Functional mesenchymal stem cell niches in adult mouse knee joint synovium in vivo

Abstract

Objective. We previously reported that human synovium contains cells that, after culture expansion, display properties of mesenchymal stem cells (MSCs). The objective of this study was to identify MSCs in native synovium in vivo.Methods. To identify stem cells in the synovium in vivo, a double nucleoside analog cell-labeling scheme was used in a mouse model of joint-surface injury. For labeling of slow-cycling cells, mice received iododeoxyuridine (IdU) for 30 days, followed by a 40-day washout period. For labeling of cells that proliferate after injury, mice underwent knee surgery to produce an articular cartilage defect and received chlorodeoxyuridine (CIdU) for 4 days, starting at multiple time points after surgery. Unoperated and sham-operated joints served as controls. Knee joint paraffin sections were analyzed by double and triple immunostaining to detect nucleoside analogs, conventional MSC markers, and chondrocytelineage markers.Results. Long-term-retaining, slow-cycling IdUpositive cells were detected in the synovium. At 4 days and 8 days after injury, there was marked proliferation of IdU-positive cells, which costained for CIdU. IdUpositive cells were nonhematopoietic, nonendothelial stromal cells, were distinct from pericytes, and stained positive for MSC markers. MSCs were phenotypically heterogeneous and located in topographically distinct niches in the lining layer and the subsynovial tissue. Twelve days after injury, double nucleoside-labeled cells within synovium were embedded in cartilagespecific metachromatic extracellular matrix and costained positive for the chondrocyte-lineage markers Sox9 and type II collagen.Conclusion. Our findings provide the first evidence of the existence of resident MSCs in the knee joint synovium that undergo proliferation and chondrogenic differentiation following injury in vivo.

In Vivo Identity of Tendon Stem Cells and the Roles of Stem Cells in Tendon Healing

“…The use of nucleotide analogs such as IdU to label stem cells in vivo has been widely reported [16,17]. Stem cells are hypothesized to preferability retain the nucleotide analogs due to their slow cycling property or by ACD-NRCC [16][17][18][19].…”

“…The participation of endogeneous stem cells in tissue repair via migration, proliferation, and differentiation was also reported in other tissues. Using the bromodeoxyuridine label-retaining method, Kurth et al reported that MSCs identified in vivo in the knee joint synovium proliferated and differentiated into chondrocytes in areas of cartilage metaplasia within the synovium after articular cartilage injury [16]. Using a genetic lineage tracing technique, Feng et al [24] has recently demonstrated the direct differentiation of a small percentage of genetically marked pericytes to odontoblasts both during incisor growth and repair after damage.…”

“…Whether and how they participate in tendon repair has not been studied. In this study, we took advantage of the slow-cycling or asymmetric-cell division with nonrandom-chromosomalcosegregation (ACD-NRCC) properties of stem cells to investigate the spatial distribution of stem cells in tendons and how stem cells participate at the early stage of tendon repair 3128 after injury using the iododeoxyuridine (IdU) label-retaining method [16][17][18][19]. The relationship between TDSCs isolated in vitro and tendon stem cells in vivo was also explored.…”

A review of decellularized stem cell matrix: a novel cell expansion system for cartilage tissue engineering

“…Synovium-derived stem cells (SDSCs) are cartilage tissue-specifi c stem cells (Sakaguchi et al, 2005;Mochizuki et al, 2006;Pei et al, 2008;Dickhut et al, 2009;Segawa et al, 2009Kurth et al, 2011. Porcine SDSCs were utilized as a model to reconstruct an in vitro 3D stem cell niche for chondrogenesis (He et al, 2009).…”

Immunostaining of Skeletal Tissues

“…BrdU) for pulse chase to detect proliferating cells. We recently used a double nucleoside analogue labelling strategy in a mouse model of articular cartilage knee joint injury to identify and characterise functional mesenchymal stem cells within the synovium in vivo (2). Of note, this study was performed using mainly IHC methods.…”