Influence of NF-kB Signaling on Human Mesenchymal Stem Cell Differentiation

Regeneration of oral tissues involves the lineage specific differentiation of mesenchymal stem cells (MSCs). This process may be affected by inflammatory events in affected oral tissues. Objective: We hypothesize that NF-κB signaling affects lineage specific transcriptional regulation of human MSCs. The effect of NF-κB and the IκBsuper repressor (SR) expression was examined during osteogenic (O), chondrogenic (C) and adipogenic (A) differentiation. Methods: Human MSCS (Lonza) were expanded, passaged and subsequently transduced with an adenovirus encoding GFP only, NF-κB or SR (MOI 5,000:1). After 24 hours, transduced cells were differentiated using O- , C- , and A-specific differentiation media for a period of 28 days. At 7, 14 and 28 days, total RNA was isolated from cells and cDNA was made. The abundance of RUNX-2, SOX-9 and PPAR- γ encoding mRNA was determined by real time PCR. Results: Differentiation of human MSCs along the O, C, and A lineages was confirmed by time-dependent expression of BSP, Col II, and PPAR-γ, respectively. Osteoblastic differentiation was positively affected by NF-κB expression with RUNX2 levels being increased 9 -and 2-fold at 7 and 14 days. SR expression did not limit RUNX2 expression compared to GFP transduced cells. SOX9 expression (chrondrogenic differentiation) was increased in SR transduced cells 2- and 8-fold at 14 and 28 days. Little change was noted in NF-κB transduced cells. Adipogenesis (PPAR-γ levels) were increased by SR expression 2.5-fold after 7 and 14 days of differentiation. Conclusion: The effect of ectopic NF-κB and SR expression in cultured human MSCs is lineage specific. Inflammatory signaling may be important in the engraftment of mesenchymal stem cells, suggesting further evaluation of inflammation in the clinical management of tissue regeneration.

1 R01 DE016986