The Roles of IGF-1 and MGF on Nerve Regeneration under Hypoxia- Ischemia, Inflammation, Oxidative Stress, and Physical Trauma

Nerve injuries and lesions often lead to the loss of neural control, reducing the patients' quality of lives. Nerve self-repair is difficult due to the low regeneration capacity, insufficient secretion of neurotrophic factors, secondary complications, and adverse microenvironmental conditions such as severe hypoxia-ischemia, inflammation, and oxidative stress. Effective therapies that can accelerate nerve regeneration have been explored. Cytokine therapy can significantly improve neural survival and myelin regeneration during nerve repair. Insulin-like growth factor-1 (IGF-1) and its isoforms (IGF- 1Ea and IGF-1Eb/Ec [also known as MGF]) represent a promising therapeutic approach regarding nerve repair, given their well-described proliferative and anti-apoptotic capacities on neurons withstanding the adverse environmental conditions. This review summarizes the research progress regarding the effects of IGF-1 and its isoforms on nerve repair after nerve injury, hypoxic-ischemic insult, inflammation, and oxidative stress. We provide a theoretical basis for the clinical treatment of nerve injuries.