[Show abstract][Hide abstract] ABSTRACT: Apoptosis has been widely reported to be involved in the pathogenesis associated with spinal cord injury (SCI). Recently, autophagy has also been implicated in various neuronal damage models. However, the role of autophagy in SCI is still controversial and its interrelationship with apoptosis remains unclear. Here, we used an in vitro SCI model to observe a time-dependent induction of autophagy and apoptosis. Mechanical injury induced autophagy markers such as LC3 lipidation, LC3II/LC3I conversion, and Beclin-1expression. Injured neurons showed decreased cell viability and increased apoptosis. To elucidate the effect of autophagy on apoptosis, the mechanically-injured neurons were treated with the mTOR inhibitor rapamycin and 3-methyl adenine (3-MA), which are known to regulate autophagy positively and negatively, respectively. Rapamycin-treated neurons showed the highest level of cell viability and lowest level of apoptosis among the injured neurons and those treated with 3-MA showed the reciprocal effect. Notably, rapamycin-treated neurons exhibited slightly reduced Bax expression and significantly increasedBcl-2 expression. Furthermore, by plasmid transfection, we showed that Beclin-1-overexpressing neuronal cells responded to mechanical injury with greater LC3II/LC3I conversion and cell viability, lower levels of apoptosis, higher Bcl-2 expression, and unaltered Bax expression as compared to vector control cells. Beclin-1-knockdown neurons showed almost the opposite effects. Taken together, our results suggest that autophagy may serve as a protection against apoptosis in mechanically-injured spinal cord neurons. Targeting mTOR and/or enhancing Beclin-1 expression might be alternative therapeutic strategies for SCI.
[Show abstract][Hide abstract] ABSTRACT: Background/aims:
To explore the effects of rapamycin-induced autophagy on apoptosis in a rat model of acute spinal cord injury (SCI), and to explore the effect of rapamycin on apoptosis in primary spinal cord cell culture.
SCI was induced at T10 in female adult Sprague-Dawley rats. After injury was induced, the rats were injected with rapamycin and/or methylprednisolone and were sacrificed at various days after injury. Apoptosis and autophagy were examined with TUNEL staining and electron microscopy. Hind limb function was assessed by the Gale scale.
The expression of the apoptosis-related protein caspase-3 did not significantly increase until 21 days following injury, while increases in LC3II and LC3I began 10 days after injury, but then declined. TUNEL staining and electron microscopy confirmed that following injury autophagy occurred before apoptosis, but by 14 days after the injury, the level of autophagy had decreased significantly while the level of apoptosis showed a continued increase. Following treatment with rapamycin, apoptosis was significantly higher than in the vehicle control group, but significantly lower than in the sham-operated group, showing a protective effect of rapamycin. Gale scale grades in rats treated with rapamycin were significantly higher compared with the vehicle control group, suggesting a functional effect of rapamycin-induced inhibition of apoptosis.
The results indicate that rapamycin significantly improved the prognosis of acute SCI in rats by inhibiting cell apoptosis. Rapamycin might be useful as a therapeutic agent for acute SCI.
No preview · Article · Mar 2014 · NeuroImmunoModulation
[Show abstract][Hide abstract] ABSTRACT: To investigate neurological effects of transplanting bone marrow-derived mesenchymal stem cells (BMSCs) transfected with the basic fibroblast growth factor (bFGF) gene in spinal cord-injured rats.
Ninety-six male adult Sprague-Dawley rats were randomized into four groups: (1) pcDNA3.1-bFGF group; (2) pcDNA3.1 group; (3) BMSCs group; and (4) vehicle control (DMEM) group. After the rat model of acute spinal cord injury (SCI) was established, 1×10(6) BMSCs or cells transfected with pcDNA3.1-bFGF or pcDNA3.1 were injected into rats of groups 1-3. At days 1, 7, 14, and 21 after injection, the Basso-Beattie-Bresnahan (BBB) locomotor rating scale was used to evaluate recovery of motor function. Expression changes of bFGF, myelin basic protein (MBP), and NF200 were examined by immunohistochemistry.
The BBB score of DMEM group was significantly lower than those of groups 1-3 (P<0.05), but the score of pcDNA3.1-bFGF group was significantly higher than that of BMSCs group or pcDNA3.1 group at day 14 or 21 after injection (P<0.01). The number of bFGF-positive neurons in rats of pcDNA3.1-bFGF group was significantly higher than those of groups 1-3 at any time point (P<0.05). The optical density values of NF200-positive neurons and MBP-positive MBP axons in rats of pcDNA3.1-bFGF group were significantly higher than those of groups 1-3 at day 7 or 14 after injection (P<0.05).
bFGF gene-modified BMSCs not only effectively promoted axonal outgrowth but also enhanced recovery of neurological function after SCI in rats, and may be a good candidate to evaluate gene therapy of SCI in man.
No preview · Article · Sep 2011 · Neurological Research