Osteoarthritic chondrocyte-secreted morphogens induce chondrogenic differentiation of human mesenchymal stem cells.
OBJECTIVE
The potential of stem cells to repair compromised cartilage tissue, such as in osteoarthritis (OA), depends strongly on how transplanted cells respond to factors secreted from the residing OA chondrocytes. This study was undertaken to determine the effect of morphogenetic signals from OA chondrocytes on chondrogenic differentiation of human mesenchymal stem cells (MSCs).


METHODS
The effect of OA chondrocyte-secreted morphogens on chondrogenic differentiation of human MSCs was evaluated using a coculture system involving both primary and passaged OA chondrocytes. The findings were compared against findings for human MSCs cultured in OA chondrocyte-conditioned medium. Gene expression analysis, biochemical assays, and immunofluorescence staining were used to characterize the chondrogenic differentiation of human MSCs. Mass spectrometry analysis was used to identify the soluble factors. Numerical analysis was carried out to model the concentration profile of soluble factors within the human MSC-laden hydrogels.


RESULTS
The human MSCs cocultured with primary OA chondrocytes underwent chondrogenic differentiation even in the absence of growth factors; however, the same effect could not be mimicked using OA chondrocyte-conditioned medium or expanded cells. Additionally, the cocultured environment down-regulated hypertrophic differentiation of human MSCs. Mass spectrometry analysis demonstrated cell-cell communication and chondrocyte phenotype-dependent effects on cell-secreted morphogens.


CONCLUSIONS
The experimental findings, along with the results of the numerical analysis, suggest a crucial role of soluble morphogens and their local concentrations in the differentiation pattern of human MSCs in a 3-dimensional environment. The concept of using a small number of chondrocytes to promote chondrogenic differentiation of human MSCs while preventing their hypertrophic differentiation could be of great importance in formulating effective stem cell-based cartilage repair.
Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Aereas
A
Aung
Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Gunjan
G
Gupta
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Ghassemian
G
Majid
Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Shyni
S
Varghese
D000368:Aged; D000704:Analysis of Variance; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D020219:Chondrogenesis / Q000502:physiology*; D018920:Coculture Techniques; D017077:Culture Media, Conditioned; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D013058:Mass Spectrometry; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D008875:Middle Aged; D010003:Osteoarthritis / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017077:Culture Media, Conditioned