The reduction in immunogenicity of neurotrophin overexpressing stem cells after intra-striatal transplantation by encapsulation in an in situ gelling collagen hydrogel

Delivery of neurotrophic factors to the brain via genetically modified bone marrow-derived mesenchymal stem cells (MSCs) offers a promising neuroprotective strategy for neurodegenerative diseases. However, MSCs delivered to the CNS typically show poor survival post-transplantation, which is accompanied by microglial activation and astrocyte recruitment at the graft site. Recent studies have shown the potential of biomaterials to provide a supportive matrix for transplanted cells which may assist in the grafting process. In this study, an in situ gelling type I collagen hydrogel was evaluated as an intracerebral transplantation matrix for delivery of glial cell line-derived neurotrophic factor (GDNF)-overexpressing MSCs to the rat brain (GDNF-MSCs). In vitro analyses demonstrated that this collagen hydrogel did not affect the viability of the GDNF-MSCs nor did it prevent GDNF secretion into the surrounding medium. In vivo analyses also confirmed that the collagen hydrogel did not negatively impact on the survival of the cells and permitted GDNF secretion into the striatal parenchyma. Importantly, this study also revealed that transplanting GDNF-MSCs in a collagen hydrogel significantly diminished the host brain's response to the cells by reducing the recruitment of both microglia and astrocytes at the site of delivery. In conclusion, this hydrogel, which is composed of the natural extracellular matrix, collagen, was shown to be a well-tolerated cell delivery platform technology which could be functionalised to further aid cell support and graft integration.     

在GDNF基因修饰的骨髓基质细胞与缺氧复氧神经细胞的共培养中神经细胞凋亡的变化

目的：探讨胶质源性神经营养因子（GDNF）基因修饰的骨髓基质细胞（BMSCs）对缺氧复氧神经细胞的保护作用。方法：GDNF基因修饰的BMSCs（BMSCs/GDNF）经诱导后与缺氧复氧神经细胞共培养,采用Hoechst33258检测神经细胞凋亡在共培养细胞中的表达。结果：BMSCs/GDNF组的神经细胞凋亡率显著低于BMSCs组和缺氧组（P〈0.05）。结论：BMSCs/GDNF通过抑制缺氧复氧神经细胞凋亡发挥神经保护作用。     

输注重组GDNF过表达的间质干细胞改善肾毒性血清肾炎肾功能

 【目的】 观察输注GDNF过表达的骨髓间质干细胞对大鼠肾毒性血清肾炎(NSN)的疗效。【方法】 构建含绿色荧光蛋白的胶质细胞源性神经营养因子(GDNF)重组腺病毒表达质粒(pAd-GDNF-GFP)并转染骨髓间质干细胞(MSC)。成年雌性SD大鼠肾毒性血清肾炎模型20只,分为3组,实验组8只大鼠经肾动脉输注转染pAd-GDNF-GFP阳性MSC,6只输注pAd-GFP(不含GDNF)阳性MSC和6只输注培养基作为对照。病理切片HE染色观察各组肾脏病理变化情况,测定血清肌酐(Cr)、尿素氮(BUN)并计算肌酐清除率。对数据组间差异进行ANOVA方差分析。【结果】 实验组病理HE染色可见肾小球的病变程度减轻,肾小管坏死和扩张减少,炎症细胞的聚集减少,肾脏组织细胞结构修复完整,提示炎症得到改善。同时实验组蛋白尿症状减轻,血清肌酐(Cr)和尿素氮降低,肌酐清除率改善,与对照组差别具有统计学意义(P < 0.05)。【结论】 输注GDNF过表达的MSC能够改善NSN大鼠肾功能和逆转发病肾脏的病理改变,起到了较好的治疗效果。     

Trophic factors for Parkinson's disease: Where are we and where do we go from here?

Perhaps the most important unmet clinical need in Parkinson's disease (PD) is the development of a therapy that can slow or halt disease progression. Extensive preclinical research has provided evidence for the neurorestorative properties of several growth factors, yet only a few have been evaluated in clinical studies. Attempts to achieve neuroprotection by addressing cell‐autonomous mechanisms and targeting dopaminergic neurons have been disappointing. Four different trophic factors have so far entered clinical trials in PD: glial cell line‐derived growth factor, its close structural and functional analog neurturin, platelet‐derived growth factor and cerebral dopaminergic neurotrophic factor. This article reviews the pre‐clinical evidence for the neuroprotective and neurorestorative actions of these growth factors and discusses limitations of preclinical models, which may hamper successful translation to the clinic. We summarize the previous and ongoing clinical trials using growth factors in PD and emphasize the caveats in clinical trial design that may prevent the further development and registration of potentially neuroprotective and neurorestorative treatments for individuals suffering from PD.     

Neurotrophic factors in Alzheimer's and Parkinson's diseases: implications for pathogenesis and therapy

Neurotrophic factors comprise essential secreted proteins that have several functions in neural and non-neural tissues, mediating the development, survival and maintenance of peripheral and central nervous system. Therefore, neurotrophic factor issue has been extensively investigated into the context of neurodegenerative diseases. Alzheimer's disease and Parkinson's disease show changes in the regulation of specific neurotrophic factors and their receptors, which appear to be critical for neuronal degeneration. Indeed, neurotrophic factors prevent cell death in degenerative processes and can enhance the growth and function of affected neurons in these disorders. Based on recent reports, this review discusses the main findings related to the neurotrophic factor support – mainly brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor – in the survival, proliferation and maturation of affected neurons in Alzheimer's disease and Parkinson's disease as well as their putative application as new therapeutic approach for these diseases management.     

小续命汤对急性脑缺血再灌注损伤BDNF,GDNF表达的影响

目的:观察小续命汤对大鼠急性脑缺血再灌注损伤后脑源性神经营养因子(brain derived neurotrophic factor,BDNF),胶质细胞源性神经营养因子(glial cell line-derived neurotrophic factor,GDNF)表达的影响。方法:60只雄性SPF级SD大鼠随机分为假手术组、模型组、小续命汤低、中、高(15,30,60 g·kg~(-1))剂量组。各组大鼠于造模前3 d开始给药直至观察节点结束,采用大脑中动脉线栓法建立脑缺血再灌注损伤模型,采用苏木素-伊红(HE)染色,Nissl染色观察脑缺血再灌注损伤,采用蛋白免疫印迹法(Western blot)和免疫组织化学法检测脑缺血再灌注损伤后的BDNF,GDNF蛋白表达。结果:与模型组比较,小续命汤高、中剂量组可显著改善其神经功能缺损(P0.05),减轻脑缺血再灌注引起的缺血性损伤;小续命汤高、中剂量组还可显著上调BDNF,GDNF蛋白表达(P0.05)。结论:小续命汤可能通过上调脑缺血再灌注后缺血半暗带区BDNF,GDNF的表达发挥脑保护的作用。     

Regulation and effects of neurotrophic factors after neural stem cell transplantation in a transgenic mouse model of Alzheimer disease

According to much research, neurodegeneration and cognitive decline in Alzheimer disease (AD) are correlated with alternations of neurotrophic factors such as nerve growth factor, brain‐derived neurotrophic factor, and glial cell–derived neurotrophic factor. The experimental illumination of neural stem cell (NSC) transplantation to eliminate AD symptoms is being explored frequently, and we have acknowledged that neurotrophic factors may play a pivotal role in cognitive improvement. However, the relation between the reversal of cognitive deficits after NSC transplantation and directed alternations of neurotrophic factors is not clearly expounded. Meanwhile, reduced inflammatory response, promoted vessel density, and vascular endothelial growth factor (VEGF) can be reflections of improvement in cerebrovascular function. Three weeks after NSC transplantation, spatial learning and memory function in NSC‐injected (Tg‐NSC) mice were significantly improved compared with vehicle‐injected (Tg‐Veh) mice. Meanwhile, results obtained by immunofluorescence and Western blot analyses demonstrated that the levels of neurotrophic factors, VEGF, and vessel density in the cortex of Tg‐NSC mice were significantly enhanced compared with Tg‐Veh mice, while the levels of proinflammatory cytokines interleukin (IL)‐1β, tumor necrosis factor‐α, and IL‐6 were significantly decreased. Our results suggest that elevated concentrations of neurotrophic factors probably play a critical role in rescuing cognitive dysfunction in APP/PS1 transgenic mice after NSC transplantation, and neurotrophic factors may improve cerebrovascular function by means such as reducing inflammatory response and promoting angiogenesis.     

Neuroprotection of retinal ganglion cells with GDNF-Loaded biodegradable microspheres in experimental glaucoma

Glaucoma is the second leading cause of blindness worldwide, and also the most common optic neuropathy. The ultimate cause of vision loss in glaucoma is thought to be retinal ganglion cell (RGC) death. Neuroprotection of RGC is therefore an important goal of glaucoma therapy. Currently, glaucoma treatment relies on pharmacologic or surgical reduction of intraocular pressure (IOP). It is critical to develop treatment approaches that actively prevent the death of RGCs at risk in glaucoma. Neurotrophic factors have the ability to promote the survival and influence the growth of neurons. Neurotrophic factor deprivation has been proposed as one mechanism leading to RGC death in glaucoma. Effective neuroprotection in glaucoma likely requires the consistent availability of the active agent for prolonged periods of time. Biodegradable microspheres are especially attractive as drug delivery vehicles for a number of reasons. Sustained GDNF delivery by biodegradable microspheres offers significant neuroprotection to injured RGC in experimental glaucoma. PLGA microsphere-delivered GDNF represents an important neuroprotective strategy in the treatment of glaucomatous optic neuropathy and provides direction for further investigations of this hypothesis.