Optimal Medium Formulation for the Long-term Expansion and Maintenance of Human Periodontal Ligament Stem Cells

Background: Human periodontal ligament stem cells (hPDLSCs) are promising mesenchymal stem cells that are readily accessible. However, there is as yet no consensus as to the optimal culture medium for hPDLSCs. Thus, the purpose of the present study is to determine the optimal culture medium for long-term expansion of hPDLSCs.

Methods: hPDLSCs were isolated from healthy third molars, and the most widely used medium formulations in previous studies were used: 1) an α minimum essential medium-based medium formulation (MBM); and 2) a Dulbecco's minimum essential medium-based medium formulation. Passage 5 (P5) and P8 were evaluated with the two media for cell proliferation, differentiation, and immunophenotype.

Results: hPDLSCs that were primarily cultured in MBM were far more proliferated than those grown in DBM. In general, application of the MBM for longer periods produced greater cell growth and osteogenic differentiation. Furthermore, MBM-precultured hPDLSCs exhibited a greater degree of cell proliferation and a greater production of mineralized tissue and alkaline phosphatase (ALP) activity in vitro, although the levels of both were dependent on the culture medium used. With respect to long-term expansion, the P5 hPDLSCs grew and produced the largest amount of mineralized nodules faster than the P8 hPDLSCs, but both passages exhibited a similar phenotype for stemness and ALP activity.

Conclusion: The present study indicates that the inherent capacity of hPDLSCs could be maintained until a later passage, P8 in MBM, and MBM appears to be an optimal choice for manipulating the finest and most stable hPDLSCs.