Investigation of the Effects of the Use of Stem Cells and Their Products in Combination with Iron Chelating Agents on Healing in Spinal Cord Injury
Project no. 23153 · Status: Kapanmış · 2021
Summary
<p>Spinal cord injuries can be broadly classified into primary and secondary injury phases. The primary damage is the most critical factor determining the extent of injury, and it occurs at the time of the initial physical force that caused the injury. On the other hand, the secondary injury cascade refers to a series of changes that begin shortly after the spinal cord injury and can persist for up to 6 months after the initial incident. Studies have shown that the loss of functional cells due to secondary damage mechanisms exceeds the loss caused by the primary damage. Promising therapeutic approaches aim to mitigate the effects of secondary damage pathways and are significant in the search for effective treatments. Recent research has revealed three new non-apoptotic controlled cell death pathways: necroptosis, pyroptosis, and ferroptosis. Following their discovery, the focus of scientific efforts has shifted towards developing new treatment strategies by understanding the roles of these pathways in various diseases. However, it is crucial to remember that the cell productiondestruction cycle plays a vital role in maintaining homeostasis. Therefore, inhibiting these controlled cell death pathways during disease treatment may potentially lead to other health issues. When interpreting or applying data from such studies, it is essential to consider that biochemical pathways may behave differently in in-vivo and in-vitro settings. Additionally, dose-dependent effects can vary significantly at different dosage levels within the same model. To provide a brief summary of the molecular steps involved in ferroptosis, it is characterized by the depletion of glutathione (GSH) and the accumulation of iron within the cell. This leads to the inactivation of GPX4 (Glutathione peroxidase 4), which is responsible for reducing lipid peroxides. Consequently, there is an increase in lipid peroxidation and lipid reactive oxygen species within the cell. In potential new therapeutic endeavors aimed at suppressing the ferroptosis pathway, several key mechanisms can be targeted. These include preventing the accumulation of iron, inhibiting the increase of reactive oxygen species, and mitigating lipid peroxidation. It is important to note that the heterogeneity and complexity of the ferroptosis-related pathways suggest the existence of numerous unknown factors that are yet to be discovered in this field. VI While it has been clearly demonstrated that ferroptosis is involved in secondary damage pathways following spinal cord injury, a definitive therapeutic advantage that can be translated into clinical practice has not been achieved yet. Further research and development are needed to fully harness its potential in clinical applications. Previous studies have explored and demonstrated the therapeutic efficacy of deferoxamine following spinal cord injury. However, what remains unidentified here are the pathways through which deferoxamine operates and the potential regulators involved in this process. Numerous studies have investigated the silibinin molecule using different models, demonstrating its antioxidant, pro-apoptotic, and anti-inflammatory properties. These pharmacological effects have been observed in both in-vivo and clinical studies, showcasing its neuroprotective, hepatoprotective, anti-cancer, anti-diabetic, cardioprotective, and immunomodulatory properties. Notably, silibinin's antioxidant activity stands out, as it directly neutralizes reactive oxygen species (ROS) such as O2-, H2O2, and OH , modulates signal pathways (Nrf2, PPAR, NF-kB), increases the levels of antioxidant enzymes (SOD, CAT, GPX), suppresses prooxidant enzymes (NOX, Xanthine oxidase), and chelates metal ions. Our study was designed as an experimental animal model, where we utilized the clipcompression method to induce spinal cord injury. We collected samples from the spinal cord tissue at 24 hours, 72 hours, and 6 weeks. These samples were then subjected to biochemical analyses to measure Fe+2, GSH, GPX4, TfR1, FPN, MDA, and 4-HNE levels. To assess functional improvement, we employed the BBB locomotor scale as an evaluation tool. Based on the data obtained from this study, it was revealed that iron chelation plays a significant role in mediating the effects of silibinin. The results indicated that the silibinin molecule effectively reduces MDA levels compared to the spinal cord injury (SCI) group, although DFO demonstrates a more pronounced reduction in MDA levels starting from the 72nd hour. Additionally, the application of DFO consistently maintains higher GSH levels throughout all three time points compared to the untreated group and significantly inhibits the GPX4 pathway. These findings support the notion that silibinin exerts its antioxidant activity through GSH and has the potential to enhance the activity of GPX4, a crucial enzyme in the context of ferroptosis. Regarding 4-HNE levels, the effectiveness of DFO diminishes after long- VII term treatment, whereas the silibinin group continues to significantly decrease 4-HNE levels throughout the follow-up period. Thus, silibinin appears to be more effective than DFO in reducing lipid peroxidation products based on the 4-HNE values. Both DFO and silibinin demonstrated short-term effects on TfR1. Functionally, both treatments led to higher recovery scores at the end of the 6-week follow-up period compared to the control group, with silibinin receiving higher scores in the direct comparison between silibinin and DFO. The therapeutic efficacy of the silibinin molecule in the spinal cord injury model can be attributed to its antiferroptotic effects on iron metabolism and its impact on lipid peroxidation. Silibinin's effectiveness was demonstrated to surpass that of deferoxamine, resulting in a more significant locomotor recovery. As such, silibinin presents itself as a superior option to deferoxamine. Nonetheless, many questions surrounding the ferroptosis pathway and its regulators remain to be answered in spinal cord injury studies and various research areas. Considering the importance of secondary cell death in spinal cord injury, therapeutic agents that can effectively and safely suppress secondary damage mechanisms may serve as promising subjects for future clinical studies </p>