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Regulating substrate mechanics to achieve odontogenic differentiation for dental pulp stem cells on TiO 2 filled and unfilled polyisoprene

We have shown that materials other than hydrogels commonly used in tissue engineering can be effective in enabling differentiation of dental pulp stem cells (DPSC).  Here we demonstrate that a hydrophobic elastomer, polyisoprene (PI), a component of Gutta-percha, normally used to obturate the tooth canal, can also be used to initiate differentiation, while their moduli can be easily adjusted either by varying the coating thickness or incorporation of inorganic particles.  DPSC plated on those PI substrates were shown, using SPM and hysitron indentation, to adjust their moduli to conform to differentially small changes in the substrate modulus.  In addition, optical tweezers were used to separately measure the membrane and cytoplasm moduli of DPSC, with and without Rho kinase inhibitor.  The results indicated that the changes in modulus were attributed predominantly to changes within the cytoplasm, rather than the cell membrane.  CLSM was used to identify cell morphology.  Differentiation, as determined by qRT-CPR, of the upregulation of OCN, and COL1α1 as well as biomineralization was deposited on both spun cast thin PI and filled thick PI substrates, the minerals were aggregated into large clusters on thin PI, and uniformly distributed  on filled thick PI, where it was templated within banded collagen fibers.

*Chuang YC, Yu Y, Wei MT, Chang C, Ricotta V, Feng K, Wang L, Bherwani A, Ou-Yang H, Simon M, Zhang L, Rafailovich M. Acta Biomaterialia 2019; 89:60