FGF21 attenuates spectrin breakdown in OGD-injured neurons but fails to improve cell survival
Background
Oxygen-glucose deprivation (OGD) is a critical in vitro model for ischemic brain injury, a leading cause of neurological disability. Current treatments for hypoxia-ischemia (HI) often fall short in preventing widespread neuronal death, which is largely driven by excitotoxicity and subsequent necrosis. Fibroblast growth factor 21 (FGF21) is a cold-stress hormone with known neuroprotective properties, including blunting α-II-spectrin breakdown product 145 (SBDP145) levels in HI models. This study investigated FGF21's dose-dependent effects on neuronal survival and specific injury markers in an OGD model.
Study Design
Researchers conducted a dose-response study using cultured human cortical neurons subjected to an oxygen-glucose deprivation (OGD) injury model. Neurons were treated with FGF21 at concentrations ranging from 100 ng/mL to 10 µg/mL post-insult. Primary endpoints included acute (24 h) and delayed (48-72 h) neuronal survival, SBDP145 levels (a marker of calpain-mediated injury), and levels of cold-shock proteins RNA-binding motif 3 (RBM3) and cold-induced RNA-binding protein (CIRBP). Control arms included combination therapy with therapeutic hypothermia (TH), and pretreatment with calpain inhibitors or the NMDA receptor antagonist MK801 to elucidate death mechanisms.
Results
FGF21 concentrations of ≥100 ng/mL significantly attenuated post-insult increases in SBDP145 levels, indicating a reduction in calpain-mediated spectrin disruption. Further, the highest dose tested, 10 µg/mL FGF21, induced a sparing effect on post-insult RBM3 levels. However, FGF21 treatment had no effect on acute (24 h) or delayed (48-72 h) neuronal survival at normothermia, either alone or when combined with intraischemic or post-treatment therapeutic hypothermia (TH). Only intraischemic TH alone robustly increased 24-h cell survival in this model. The study verified necrosis as the primary mechanism of cell death induced by OGD. Pretreatment with calpain inhibitors decreased markers of necrosis but increased markers of autophagy/apoptosis, with no effect on 24-h cell survival. In contrast, pretreatment with NMDA receptor antagonist MK801 robustly increased 24-h cell survival.
FGF21 post-treatment (≥100 ng/mL) primarily alleviated α-II-spectrin disruption in an OGD model of excitotoxicity-induced necrosis, but did not improve neuronal survival.
Key Findings
- FGF21 (≥100 ng/mL) attenuated
SBDP145levels post-OGD injury. - FGF21 (10 µg/mL) induced a sparing effect on post-insult
RBM3levels. - FGF21 had no effect on acute (24 h) or delayed (48-72 h) neuronal survival.
- Intraischemic therapeutic hypothermia was the only intervention that increased 24-h cell survival.
- NMDA receptor antagonist MK801 robustly increased 24-h cell survival.
Why It Matters
This study refines our understanding of FGF21's neuroprotective profile, suggesting it specifically targets α-II-spectrin disruption and RBM3 preservation, rather than directly improving overall neuronal survival in normothermic OGD conditions. For peptide users and biohackers, this implies that while FGF21 may mitigate certain injury markers, it might not be a standalone solution for preventing cell death in acute ischemic events. The findings highlight the complexity of neuroprotection, suggesting that FGF21's benefits might be more nuanced or require combination with other strategies, such as therapeutic hypothermia or NMDA receptor antagonists like MK801, which demonstrated robust survival benefits. FGF21 could potentially serve as an adjunct therapy to reduce specific cellular damage pathways, but its role in improving patient outcomes in acute ischemic injury remains to be fully elucidated.
fgf21
neuroprotection
oxygen-glucose-deprivation
neuronal-survival
spectrin-breakdown
in-vitro