Therapeutic effects of PDGF-AB/BB against cellular senescence in human intervertebral disc

Accumulation of senescent cells is closely linked with intervertebral disc (IVD) degeneration, a prevalent age-dependent chronic disorder causing low back pain. While previous studies have highlighted that platelet-derived growth factor (PDGF) mitigated IVD degeneration through anti-apoptotic and pro-anabolic effects, its impact on IVD cell senescence remains elusive. In this study, human NP and AF cells derived from aged, degenerated IVDs were treated with recombinant human (rh) PDGF-AB/BB for 5 d. Transcriptome profiling by mRNA sequencing revealed that NP and AF cells responded to the treatment in similar yet distinct ways. The effects of PDGF-AB and BB on human IVD cells were comparable. Specifically, rhPDGF-AB/BB treatment downregulated genes related to neurogenesis and mechanical stimulus response in AF cells, while in NP cells, metabolic pathways were predominantly suppressed. In both NP and AF cells, rhPDGF-AB/BB treatment upregulated genes involved in cell cycle regulation and response to reduced oxygen levels, while downregulating genes related to senescence-associated phenotype, including oxidative stress, reactive oxygen species (ROS), and mitochondria dysfunction. Network analysis revealed that PDGFRA and IL6 were the top hub genes in treated NP cells. Furthermore, in irradiation-induced senescent NP cells, PDGFRA gene expression was significantly reduced compared to non-irradiated cells. However, rhPDGF-AB/BB treatment increased PDGFRA expression and mitigated the senescence progression through increased cell population in the S phase, reduced SA-β-Gal activity, and decreased expression of senescence-related regulators. Our findings reveal a novel anti-senescence role of PDGF in the IVD, making it a promising potential candidate to delay aging-induced IVD degeneration.