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Clinical translation of growth factor therapies faces multiple challenges; the most significant one is the short half-life of the naked protein. Gelatin nanostructured lipid carriers (GNLs) had previously been used to encapsulate the basic fibroblast growth factor to enhance the functional recovery in hemiparkinsonian rats. In this research, we comparatively study the enhanced therapy between nerve growth factor (NGF) loaded GNLs (NGF-GNLs) and NGF only in spinal cord injury (SCI). The effects of NGF-GNLs and NGF only were tested by the Basso-Beattie-Bresnahan (BBB) locomotion scale, inclined plane test, and footprint analysis. Western blot analysis and immunofluorescent staining were further performed to identify the expression of ER stress-related proteins, neuron-specific marker neuronal nuclei (NeuN), and growth-associated protein 43 (GAP43). Correlated downstream signals Akt/GSK-3β and ERK1/2 were also analyzed with or without inhibitors. Results showed that NGF-GNLs, compared to NGF only, enhanced the neuroprotection effect in SCI rats. The ER stress-induced apoptosis response proteins CHOP, GRP78 and caspase-12 inhibited by NGF-GNL treatment were more obvious. Meanwhile, NGF-GNLs in the recovery of SCI are related to the inhibition of ER stress-induced cell death via the activation of downstream signals PI3K/Akt/GSK-3β and ERK1/2.

Endoplasmic reticulum (ER) stress plays an important role in a range of neurological disorders, such as neurodegenation diseases, cerebral ischemia, spinal cord injury, sclerosis, and diabetic neuropathy. Protein misfolding and accumulation in the ER lumen initiate unfolded protein response in energy-starved neurons which are relevant to toxic effects. In neurological disorders, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, ER dysfunction is well recognized, but the mechanisms remain unclear. In stroke and ischemia, spinal cord injury, and amyotrophic lateral sclerosis, chronic activation of ER stress is considered as main pathogeny which causes neuronal disorders. By targeting components of these ER signaling responses, to explore clinical treatment strategies or new drugs in CNS neurological diseases might become possible and valuable in the future.

Objective: To explore the effects of endoplasmic reticulum stress (ERS) related proteins and their mediated apoptosis in the formation of deep tissue injury of pressure ulcer in rats., Methods: Forty male Sprague-Dawley rats were divided into normal control group and groups A, B, C, D according to the random number table, with 8 rats in each group. Rats in group A were loaded with 22.47 kPa pressure with a special pressure apparatus for 2.0 h in the region over gracilis, and then unloaded for 0.5 h. Rats in group B were treated with the same manoeuvre as that in group A for 3 times in one day. Rats in groups C and D were treated with the same manoeuvre as that in group B for 2 and 3 days. Rats in normal control group were free from pressure loading. Rats in groups A, B, C, and D were sacrificed after pressure loading, and then the central part of pressure loaded muscular tissues were harvested for observation of histomorphological change with HE staining; apoptotic nucleoli per millimeter pressure loaded muscular tissue were counted with Hoechst 33258 staining; the levels of binding protein (BIP), protein disulfide isomerase (PDI), C/EBP homologous protein (CHOP), and caspase-12 were assessed with Western blotting (denoted as gray level ratio of target protein to GAPDH). The same parts of gracilis of rats in normal control group were harvested for determination of all the indexes as above. Data were processed with one-way analysis of variance, LSD-t test was applied for paired comparison., Results: (1) Histomorphological observation. Some pathological changes, including inflammatory cell infiltration, myofibers lysis, and vacuolar degeneration, etc. were observed in pressure loaded muscular tissue of rats in groups A, B, C, and D, but not in the same parts of gracilis muscle of rats in normal control group. Compared with those in normal control group [(2.7 ± 1.4) per millimeter muscular tissue], the number of apoptotic nuclei was significantly increased in pressure loaded muscular tissue of rats in groups A, B, C, and D [(14.5 ± 4.4), (11.0 ± 2.9) , (13.8 ± 5.1), (21.3 ± 6.0) per millimeter pressure loaded muscular tissue, with t values from 4.223 to 6.000, P values all below 0.01). (2) Western blotting. The protein expressions of BIP and PDI in rats of normal control group and groups A, B, C, D were respectively 0.64 ± 0.12, 1.20 ± 0.34, 1.59 ± 0.24, 1.17 ± 0.28, 1.44 ± 0.33; 0.48 ± 0.15, 0.61 ± 0.19, 1.23 ± 0.38, 0.37 ± 0.19, 0.29 ± 0.15, and they showed significant statistical difference (with F values respectively 5.32, 7.95, P < 0.05 or P < 0.01). The protein expressions of CHOP and caspase-12 in rats of normal control group and groups A, B, C, D were respectively 0.58 ± 0.18, 1.48 ± 0.27, 1.03 ± 0.21, 0.95 ± 0.30, 1.69 ± 0.34; 0.55 ± 0.12, 1.08 ± 0.31, 0.69 ± 0.24, 1.79 ± 0.20, 2.06 ± 0.47, with significant statistical difference (with F values respectively 8.17, 15.48, P values all below 0.01)., Conclusions: ERS related proteins and their apoptotic pathway may play an important role in the formation of deep tissue injury of pressure ulcer in rats.

Aim: To investigate the mechanism of endoplasmic reticulum (ER) stress-induced apoptosis as well as the protective action of basic fibroblast growth factor (bFGF) both in vivo and in vitro., Methods and Results: ER stress-induced apoptosis was involved in the injuries of spinal cord injury (SCI) model rat. bFGF administration improved the recovery and increased the survival of neurons in spinal cord lesions in model rat. The protective effect of bFGF is related to the inhibition of CHOP, GRP78 and caspase-12, which are ER stress-induced apoptosis response proteins. bFGF administration also increased the survival of neurons and the expression of growth-associated protein 43 (GAP43), which is related to neural regeneration. The protective effect of bFGF is related to the activation of downstream signals, PI3K/Akt/GSK-3β and ERK1/2, especially in the ER stress cell model., Conclusions: This is the first study to illustrate that the role of bFGF in SCI recovery is related to the inhibition of ER stress-induced cell death via the activation of downstream signals. Our work also suggested a new trend for bFGF drug development in central neural system injuries, which are involved in chronic ER stress-induced apoptosis., (© 2012 Blackwell Publishing Ltd.)