Conclusion
Overall, dental pulp cells readily formed rod-shaped patterns of microtissues which, over a period of time, condensed into more stable spheroidal structures. Hence, technologies like bioprinting, using direct fabrication of microtissues need to consider the contraction dynamics. Clinical relevance: The field of regenerative endodontology will benefit from our findings as it can be applied as a novel platform to test the impact of pharmacological agents, biomaterials, and regenerative approaches including bioprinting.
Methods
Human dental pulp cells were seeded into agarose molds to assemble into rod-shaped microtissues. Resazurin- and tetrazolium-based cytotoxicity assays, Live/Dead staining, and hematoxylin and eosin staining for histological evaluation of rods were performed. Rod contraction was evaluated and measured for a period of 10 days. The role of TGF-β, phosphoinositide 3-kinase (PI3K)/AKT, and mitogen-activated protein kinase (MAPK) signaling pathway was analyzed.
Results
Dental pulp cells readily assembled into rods, maintaining the geometric shape for 48 h. Following this period, they condensed to form stable spheroidal structures that remained vital for 10 days from seeding. Inhibition of phosphoinositide 3-kinase signaling pathway by LY294002 significantly prolonged the diminution in the length of rods formed by dental pulp cells. TGF-β and pharmacological inhibition of TGF-β signaling did not show pronounced effects.