Osteogenic differentiation of human umbilical cord mesenchymal stromal cells in polyglycolic acid scaffolds

Although human umbilical cord mesenchymal stromal cells (hUCMSCs) have been shown to differentiate along an osteogenic lineage in monolayer culture, the potential of these cells has seldom before been investigated in three-dimensional scaffolds for bone tissue engineering applications. In this 6-week study, we observed osteogenic differentiation of hUCMSCs on polyglycolic acid (PGA) nonwoven mesh scaffolds, and compared seeding densities for potential use in bone tissue engineering. Cells were seeded into PGA meshes with densities of 5, 25, or 50 x 10(6) cells/mL scaffold and then cultured in osteogenic medium. Cell proliferation, osteogenic differentiation, and matrix formation were evaluated at weeks 0, 3, and 6. Osteogenic differentiation was observed based on positive alkaline phosphatase activity and an increase of collagen production and calcium incorporation into the extracellular matrix, which increased with higher cell density. During differentiation, runt-related transcription factor (RUNX2), type I collagen (CI), and osteocalcin (OCN) gene expression levels were also increased. In conclusion, exposed to osteogenic signals, hUCMSCs differentiated along an osteogenic lineage as determined by expression of osteogenic markers and matrix formation, and increasing the density of hUCMSCs seeded onto three-dimensional PGA scaffolds led to better osteogenic differentiation.