Fibrinogen Induces RUNX2 Activity and Osteogenic Development from Human Pluripotent Stem Cells

Abstract

Pluripotent stem cells, both human embryonic stem cells (hESC) and induced pluripotent stem cells (iPSC), provide an important resource to produce specialized cells such as osteogenic cells for therapeutic applications such as repair or replacement of injured, diseased or damaged bone. hESCs and iPSCs can also be used to better define basic cellular and genetic mechanisms that regulate the earliest stages of human bone development. However, current strategies to mediate osteogenic differentiation of hESC and iPSC are typically limited by the use of xenogeneic components such as fetal bovine serum (FBS) that make defining specific agents that mediate human osteogenesis difficult. Runt-related transcription factor 2 (RUNX2) is a key regulator required for osteogenic differentiation. Here, we used a RUNX2-YFP reporter system to characterize the novel ability of fibrinogen to mediate human osteogenic development from hESC and iPSC in defined (serum-free) conditions. These studies demonstrate that fibrinogen mediates significant osteo-induction potential. Specifically, fibrinogen binds to the surface integrin (α9β1) to mediate RUNX2 gene expression through the SMAD1/5/8 signaling pathway. Additional studies characterize the fibrinogen-induced hESC/iPSC-derived osteogenic cells to demonstrate these osteogenic cells retain the capacity to express typical mature osteoblastic markers. Together, these studies define a novel fibrinogen-α9β1-SMAD1/5/8-RUNX2 signaling axis can efficiently induce osteogenic differentiation from hESCs and iPSCs.

LRG1 promotes proliferation and inhibits apoptosis in colorectal cancer cells via RUNX1 activation

“…RUNX1 has been shown to play a role in haematopoiesis and haematopoietic function[19]. RUNX2 has been reported to be a key regulator required for osteogenic differentiation[20], while RUNX3 has been shown to be related to gastrointestinal tract development[21]. All three RUNX genes are associated with Smads and the TGF-β signalling pathway[22–24].…”

Comparative Study of Osteogenic Activity of Multilayers Made of Synthetic and Biogenic Polyelectrolytes

“…Although the synthetic PSS/PAH system is not suitable for a clinical application as it was used here as a kind of reference system because of its known cytocompatibility . The other two systems were included due to the known osteogenic activity of fibrinogen and the inherent bioactivity of chondroitin sulfate toward proteins with heparin‐binding domains . Physical studies showed that the PSS/PAH multilayer system was well separated with intermediate wetting properties, opposing sign of charge of terminal PSS and PAH layers, which was also the case for BCS/FBG multilayer system.…”

Lineage-specific differentiation of osteogenic progenitors from pluripotent stem cells reveals the FGF1-RUNX2 association in neural crest-derived osteoprogenitors

“…6 hESC-RUNX2-YFP cells used to report differentiation into osteoprogenitors (OPs) were previously described. 10 Undifferentiated hPSCs were taken as the negative controls.…”

“…Real-time reverse-transcription polymerase chain reaction (RT-PCR) analysis was done as previously described. 10 Briefly, total RNA was extracted using Qiagen RNeasy Mini Kit (Qiagen, Valencia, California) and 1 μg of RNA was reverse transcribed into cDNA using SuperScript II Reverse Transcriptase (ThermoFisher Scientific), based on the manufacturer's instructions. Quantitative real-time RT-PCR was performed using 150 ng cDNA product with SYBR Green PCR Master Mix (Qiagen) in 25 μL per PCR reaction according to the recommended conditions as previously described.…”

“…We performed cell sorting coupled with gene expression analysis to optimize induction purity and employed a novel hESC-RUNX2-YFP reporter cell line that allowed the identification of the earliest OPs. 6,10 With our differentiation system, we characterized differences among transcriptomic patterns and highlight key markers of the three cell populations.…”