The BMP and FGF pathways reciprocally regulate odontoblast differentiation

ABSTRACT

Purpose

Previous studies demonstrated that the exposure of primary dental pulp (DP) cultures to fibroblast growth factor 2 (FGF2) between days 3–7 exerted significant and long-lasting stimulatory effects on odontoblast differentiation and Dspp expression. These effects involved the increased expression of components of bone morphogenetic protein (BMP) signaling and were reverted by a BMP inhibitor noggin. FGF2 also transiently stimulated osteoblast differentiation and the expression of Ibsp and Dmp1. The present study aimed to further explore interactions between BMP and FGF signaling during odontoblast and osteoblast differentiation in DP cultures.

Materials and Methods

Cultures were established using DP tissue isolated from non-transgenic and fluorescent reporter (DSPP-Cerulean, BSP-GFP, and DMP1-mCherry) transgenic mice and exposed to BMP2, FGF2, SU5402 (an FGF receptor inhibitor), and noggin between days 3–7. Mineralization, gene expression, fluorescent protein expression, and odontoblast formation were examined using xylenol orange, quantitative PCR, fluorometric analysis, and immunocytochemistry, respectively.

Results

BMP2 activated SMAD1/5/8 but not ERK1/2 signaling, whereas FGF2 exerted opposite effects. BMP2 did not affect mineralization, the expression of Ibsp and Dmp1, and the percentage of DSPP-Cerulean+ odontoblasts but significantly increased Dspp and DSPP-Cerulean. In cultures exposed to BMP2 and FGF2, respectively, both SU5402 and noggin led to long-lasting decreases in Dspp and DSPP-Cerulean and transient decreases in Dmp1 and DMP1-mCherry without affecting Ibsp and BSP-GFP.

Conclusion

BMP2 and FGF2 exerted reciprocal stimulatory effects on odontoblast differentiation, whereas their effects on osteoblast differentiation were mediated independently. These data will further elucidate the perspectives of using BMP2 and FGF2 for dentin regeneration/repair.

KEYWORDS:

• Bone morphogenetic protein 2
• dental pulp
• fibroblast growth factor 2
• mineralization
• odontoblasts

Acknowledgments

The author would like to thank Mrs. Barbara Rogers and Drs. Ivo Kalajzic and Peter Maye for providing reagents, valuable input, and technical assistance in various aspects of this study.

Disclosure statement

The author denies any conflicts of interest related to this study.

Author contributions

The author, KP, contributed to the conception and design of the research, performed the experiments, analyzed and interpreted the data, prepared the figures, drafted and critically revised the manuscript.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03008207.2022.2094789

Additional information

Funding

This work was supported by the NIH under grants R01-DE016689 and T90-DE022526 to Dr. Mina Mina (University of Connecticut Health, Farmington, CT, USA).