Methods: The collagen gel was paved on collagen type I floor and cultured with β-GP(-) DMEM and was designated to be the control group.
Results: Immunohistochemical studies of HDPD cells-and-collagen mixture cultured in β-GP(+) DMEM (experimental group) demonstrated differentiation of odontoblast-like cells, which secreted DSP, DSPP and collagen types I and III in the ECM. Fine structure TEM study observed they were flat and polygonal cells with many elongated cellular processes. In accordance with the increase of ALP activity and expression of DSPP mRNA of the HDPD cells, vital staining demonstrated hard tissue formation in ECM of the β-GP(+) experimental group. The TEM study also revealed initial matrix vesicle-related and subsequent collagen-related mineralization in the experimental group. Results of this in vitro study elucidate that odontogenic HDPD cells cultured in the β-GP(+) DMEM have same properties as the odontoblast-like cells observed in our previous in vivo transplantation study.
Conclusion: The HDPD cells differentiate and initiate dentin formation in the either collagen type I or gelatine scaffolds, but they showed different morphology in either in vivo or in vitro environments.