Transcriptomic analysis of ipsilateral spinal cord in rats after bone fracture

Abstract

Backgroud: A large amount of research has shown that spinal cord injury causes bone loss and increases fracture risk, while spinal cord injuries caused by fractures and their underlying molecular mechanisms still need further investigation.Methods To investigate the specific changes in the spinal cord after bone fractures, we obtained L4-L5 spinal cord segments from the same side of SD rats with tibial fractures at 0, 3, 7, 14, and 28 days after the fracture. Gene Ontology (GO) enrichment analysis, KEGG pathway analysis, and Ingenuity Pathway Analysis(IPA) were used to analyze the differential gene expression of the genes at different time points .Results Our sequencing results showed that the transcriptional changes in the spinal cord after fracture developed towards the direction of restoring normal physiological function. At 3 and 7 days after fracture, the same-side L4-L5 spinal cord segment showed significant activation of neurodegeneration and central nervous system development, with neurodegeneration activation being most significant at 3 days after fracture and the spinal cord also showing activation of cell survival regulation effects after 7 days of bone fracture. At 14 days after bone fracture, the spinal cord showed significant enrichment in the myelin sheath formation signaling pathway, activation of cell death in the central nervous system, GO terms relating to synaptic function were also significantly enriched. The spinal cord had active gene transcription, protein synthesis, and degradation metabolism processes at these three time points after fracture. At 28 days after fracture, the spinal cord showed recovery of motor function. In addition, a series of important genes in the spinal cord after fracture were differentially expressed, including PCP4 and Krit1. Rictor, TEAD1, torin1, DDX5, CAB39L, and Ngf in the spinal cord may act as upstream master regulators to play a role in fracture repair.Conclusions We speculate that local injury stimulation of the fracture through DRG enters the intermediate neurons of the spinal cord dorsal horn, triggering a series of adaptive changes including activation of neurodegeneration and central nervous system development in the spinal cord, among other changes. With the involvement of important molecules such as PCP4 and Krit1, the physiological function of the spinal cord gradually recovers after fracture, reducing the risk of disuse osteoporosis and promoting fracture repair. This study provides an understanding of the transcriptome changes in the spinal cord following fracture at different time points, and the changes observed across these time points, and screens for important genes that might participate in the regulation of spinal cord fracture healing, providing a sequencing basis for exploring the bidirectional relationship between fracture and the spinal cord.