1 research outputs found
Contribution of toll-like receptors to mesenchymal stem cell differentiation and immunomodulation
Ankara : The Department of Molecular Biology and Genetics and the Institute of Engineering and Science of Bilkent University, 2010.Thesis (Master's) -- Bilkent University, 2010.Includes bibliographical references leaves 73-86.characteristics along with several stem cell features such as lineage
dependent differentiation and self-renewal capacity. MSCs are known to induce
immunomodulatory activity and homing capacity to damaged tissue sites. Such
diverse capabilities of MSCs make them distinct from adult stem cells and can be
harnessed in several therapeutic applications.
Toll-like receptors (TLR) can recognize conserved microbial byproducts and
are mainly expressed by innate immune system cells as well as epithelial or
endothelial cells. Recent findings suggest that in vitro generated MSCs express some
of these pathogen recognition receptors. In our view, to broaden the breath of the
therapeutic potential, TLR mediated activation of MSCs and demonstrate its impact
on differentiation and immunomodulatory activity is critical.
First, bone marrow-derived MSCs were generated and characterized via their
surface marker expression by FACS (CD90, CD106 and CD45) at protein level and
their message transcripts by RT-PCR (CD11b, CD29, CD34, CD45, CD71, CD73,
CD90 and CD166). The most abundant marker was found to be CD90 over several
passages. Following determination of TLR expression profile by RT-PCR,
contribution of TLR ligands addition (TLR2, TLR3, TLR7 and TLR9) to MSCs
during adipogenic or osteogenic differentiation was studied. TLR3 was found to be
the most abundant type over several passages. The adipogenic differentiation of
rMSCs was found to be facilitated in the presence of TLR2 TLR3 and TLR7 ligands.
Additionally, changes in the adipogenic and osteogenic markers (LPL, PPAR-g for
adipogenesis, and ALP, OC-1, RUNX for osteogenesis) were analyzed by RT-PCR.
While adipogenic markers upregulated osteogenic markers were downregulated in
response to TLR ligand treatment.
The final part of this study was performed with mouse mesenchymal stem
cells. In order to define the immunostimulatory/immunosuppressive potential of
mouse MSCs, immunomodulatory character of MSCs were examined in the presence
or absence of mouse spleen cells. Our data suggested that when mMSCs are primed
with TLRL, a pro-inflammatory cascade as evidenced by increased IL-6 and IFN-γ
secretion is initiated either alone or in co-culture with splenocytes.
In conclusion, TLR priming of MSCs augments their differentiation primarily
into adipogenesis, and mainly these cells are immunostimulatory.Taş, İbrahim FıratM.S