Microcarrier culture enhances osteogenic potential of human periodontal ligament stromal cells

Regeneration of periodontal tissue represents a major challenge to modern tissue engineering, since cell-based therapies require large amounts of periodontal ligament stromal cells (PLSC), which can be obtained only by in vitro expansion. Ideally, the period of the in vitro expansion should be optimized for the generation of large enough numbers of pre-specified progenitor cells ready to contribute to the restoration of periodontal tissues.In the present study, we used a commercially available, three-dimensional culturing platform and alginate microcarrier cell culture system for the propagation of human PLSCs, which were derived using the explant outgrowth method. Induction of osteogenic differentiation resulted in rapid and robust mineralization of the extracellular matrix in PLSCs grown on microcarriers, but not in PLSCs grown under standard culture conditions. Gene expression studies revealed upregulation of osteogenesis-related genes, BMP2, ALP, RUNX2, MSX2, cementum protein 23, bone sialoprotein, osteopontin and periostin, in undifferentiated and differentiating microcarrier cultures of PLSCs. In addition, the microcarrier culture enhanced the expression of β-catenin, intermediate filament protein vimentin and focal adhesion proteins vinculin and paxillin.Our study shows that microcarrier culture allows rapid generation of large numbers of PLSCs pre-specified towards an osteogenic-like phenotype. This method may be useful for the development of new tissue engineering protocols for the reconstruction of periodontal tissues.