Identification of five developmental processes during chondrogenic differentiation of embryonic stem cells.
BACKGROUND
Chondrogenesis is the complex process that leads to the establishment of cartilage and bone formation. Due to their ability to differentiate in vitro and mimic development, embryonic stem cells (ESCs) show great potential for investigating developmental processes. In this study, we used chondrogenic differentiation of ESCs as a model to analyze morphogenetic events during chondrogenesis.


RESULTS
ESCs were differentiated into the chondrocyte lineage, forming small cartilaginous aggregates in suspension. Differentiated ESCs showed that chondrogenesis was typically characterized by five overlapping stages. During the first stage, cell condensation and aggregate formation was observed. The second stage was characterized by differentiation into chondrocytes and fibril scaffold formation within spherical aggregates. Deposition of cartilaginous extracellular matrix and cartilage formation were hallmarks of the third stage. Apoptosis of chondrocytes, hypertrophy and/or degradation of cartilage occurred during the fourth stage. Finally, during the fifth stage, bone replacement with membranous calcified tissues took place.


CONCLUSIONS
We demonstrate that ESCs show the chondrogenic differentiation pathway from the pluripotent stem cell to terminal skeletogenesis through these five stages in vitro. During each stage, morphological changes acquired in preceding stages played an important role in further development as a scaffold or template in subsequent stages. The study of chondrogenesis via ESC differentiation may be informative to our further understanding of skeletal growth and regeneration.
Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta, Canada.
Akihiro
A
Yamashita
Sandi
S
Nishikawa
Derrick E
DE
Rancourt
D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D017931:DNA Primers; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006025:Glycosaminoglycans / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D051379:Mice; D008855:Microscopy, Electron, Scanning; D012313:RNA / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D006025:Glycosaminoglycans; D012313:RNA; D002118:Calcium