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Description
Introduction
Mesenchymal stem cells (MSCs) are widely used in the fields of cell therapy and tissue engineering, due to their wide spectrum of differentiation potential, immunomodulation function and ongoing oxidative stress (OS) reduction. OS impact is often overlooked in these research fields, even though, it is not only responsible for the induction and development of many ailments, e.g., diabetes, lung fibrosis, and cancer, but it also causes stem cell death and senescence during cell therapy and tissue engineering practices. As MSCs are used to treat different types of tissues, these cells interact with different tissue-specific mechanical environments, thus it is important to understand how the mechanical environment impacts MSC sensitivity to OS.
Methodology
In this study, human gingival mesenchymal stem cells (GMSCs) were used (approval No. 158200-16- 860-369 2016-07-12) To study the impact of mechanical environment collagen type I coated acrylamide - bisacrylamide hydrogels were used. Three different stiffness surfaces, which mimicked soft (1 kPa), medium (8 kPa) and hardest (40 kPa) stiffness tissues, were used in this study. Cell-surface interaction was observed with immunocytochemistry, proliferation and cytotoxicity evaluation methods. Mitogen-activated protein kinases (MAPK) – ERK, JNK, p38 and transcription factors c-Jun and c-Fos role was evaluated by Western blot and MAPK inhibitors assays.
Results
Gingival MSCs were isolated from healthy volunteers during wisdom tooth extraction. These cells expressed CD44, CD90, CD105, CD166 surface markers, were negative for hematopoietic CD19, CD45 markers, and were able to differentiate into adipose, muscle and osteogenic cells. GMSCs interaction with polyacrylamide hydrogels were surface stiffness depended. The stiffer the surface the more strongly cells interacted with the hydrogels. Also, cells demonstrated higher proliferative activity on stiffer surfaces. Furthermore, GMSC sensitivity to OS increased on softer surfaces. MAPK expression analysis revealed, that their levels and phosphorylation is also surface stiffness dependent. Even so, their role changes when GMSC were grown on different stiffness polyacrylamide hydrogels.
Conclusions
In this work, for the first time, as known to the authors, it was shown that GMSCs sensitivity to OS depends on the stiffness of the surface, on which the cells are grown. Furthermore, the activity and expression of MAPK ERK, JNK, and p38 were also surface stiffness dependent. GMSCs isolated from intermediate/stiff gingiva tissue (~20 kPa) have shown the best proliferative and survival properties, then grown on the stiffest tissues mimicking polyacrylamide hydrogels (40 kPa). Therefore, MSC source might determine their sensitivity to OS in different stiffness environments and should be accounted for when developing a treatment strategy.
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