Effect of Whole Tissue Culture and Basic Fibroblast Growth Factor on Maintenance of Tie2 Molecule Expression in Human Nucleus Pulposus Cells

Abstract

Previous work showed a link between Tie2+ nucleus pulposus progenitor cells (NPPC) and disc degeneration. However, NPPC remain difficult to maintain in culture. Here, we report whole tissue culture (WTC) combined with fibroblast growth factor 2 (FGF2) and chimeric FGF (cFGF) supplementation to support and enhance NPPC and Tie2 expression. We also examined the role of PI3K/Akt and MEK/ERK pathways in FGF2 and cFGF-induced Tie2 expression. Young herniating nucleus pulposus tissue was used. We compared WTC and standard primary cell culture, with or without 10 ng/mL FGF2. PI3K/Akt and MEK/ERK signaling pathways were examined through western blotting. Using WTC and primary cell culture, Tie2 positivity rates were 7.0 ± 2.6% and 1.9 ± 0.3% (p = 0.004), respectively. Addition of FGF2 in WTC increased Tie2 positivity rates to 14.2 ± 5.4% (p = 0.01). FGF2-stimulated expression of Tie2 was reduced 3-fold with the addition of the MEK inhibitor PD98059 (p = 0.01). However, the addition of 1 μM Akt inhibitor, 124015-1MGCN, only reduced small Tie2 expression (p = 0.42). cFGF similarly increased the Tie2 expression, but did not result in significant phosphorylation in both the MEK/ERK and PI3K/Akt pathways. WTC with FGF2 addition significantly increased Tie2 maintenance of human NPPC. Moreover, FGF2 supports Tie2 expression via MEK/ERK and PI3K/Akt signals. These findings offer promising tools and insights for the development of NPPC-based therapeutics.

Intervertebral Disc Degeneration: Biomaterials and Tissue Engineering Strategies toward Precision Medicine

“…Recent advancement of biomaterials as a delivery system has provided a broad range of benefits in tissue engineering and regenerative medicine. [78] Biomaterials can transport exogenous therapeutic molecules, including growth factors (PDGF, FGF, IGF-I, and TGF-𝛽1), [79,80,81,82] cellular regulator, drug or inhibitor (anti-TNF𝛼, IL-1ra, celecoxib, rapamycin, NF-𝜅B decoy) [83,84,85,86] from the cargo to the target site specifically to regulate cellular signaling, thereby dictating cellular responses, including anticatabolic, antioxidative, antiapoptotic, anti-inflammatory, and anabolic effects for IVD regeneration. [87] This delivery system provides sustained release of the therapeutic molecules over time for a longterm efficacy.…”

Clinical Development of Regenerative Medicine Targeted for Intervertebral Disc Disease

“…Moreover, these chondrogenic cells types present a limited proliferation capacity and tend to lose their phenotypical features rapidly in vitro [6,79]. Although culture optimization strategies are being explored to enhance the expandability of these cell types [80][81][82].…”

Concepts of Regeneration for Spinal Diseases in 2021

“…However, it is difficult to enhance and maintain these cells in standard monolayer culture systems. Sako K et al [8] therefore tested the efficacy of whole tissue cultures combined with fibroblast growth factor 2 supplementation using human young herniated disc NP tissues, which increased Tie2 maintenance through the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase/ERK kinase and to a lesser extent phosphatidylinositol-3 kinase/Akt pathways. These techniques are useful for human disc NP progenitor cell expansion and experimentation.…”