Myeloid-derived suppressor cells (MDSCs) constitute a recently discovered bone-marrow-derived cell type useful for dealing with neuroinflammatory disorders. However, these cells are only formed during inflammatory conditions from immature myeloid cells (IMCs) that acquire immunosuppressive activity, thus being commonly gathered from diseased animals. Then, to obtain a more clinically feasible source, we characterized IMCs directly derived from healthy bone marrow and proved their potential immunosuppressive activity under pathological conditions in vitro. We then explored their neuroprotective potential in a model of human cerebellar ataxia, the Purkinje Cell Degeneration (PCD) mouse, as it displays a well-defined neurodegenerative and neuroinflammatory process that can be also aggravated by invasive surgeries. IMCs were obtained from healthy bone marrow and co-cultured with activated T cells. The proliferation and apoptotic rate of the later were analyzed with Tag-it Violet. For in vivo studies, IMCs were transplanted by stereotactic surgery into the cerebellum of PCD mice. We also used sham-operated animals as controls of the surgical effects, as well as their untreated counterparts. Motor behavior of mice was assessed by rotarod test. The Purkinje cell density was measured by immunohistochemistry and cell death assessed with the TUNEL technique. We also analyzed the microglial phenotype by immunofluorescence and the expression pattern of inflammation-related genes by qPCR. Parametric tests were applied depending on the specific experiment: one or two way ANOVA and Student’s T test. IMCs were proven to effectively acquire immunosuppressive activity under pathological conditions in vitro, thus acting as MDSCs. Concerning in vivo studios, sham-operated PCD mice suffered detrimental effects in motor coordination, Purkinje cell survival and microglial activation. After intracranial administration of IMCs into the cerebellum of PCD mice, no special benefits were detected in the transplanted animals when compared to untreated mice. Nonetheless, this transplant almost completely prevented the impairments caused by the surgery in PCD mice, probably by the modulation of the inflammatory patterns. Our work comprise two main translational findings: (1) IMCs can be directly used as they behave as MDSCs under pathological conditions, thus avoiding their gathering from diseased subjects; (2) IMCs are promising adjuvants when performing neurosurgery.

中文翻译：

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小脑内注射单核未成熟骨髓细胞可预防小脑神经变性模型中立体定向手术引起的不良反应

骨髓源性抑制细胞（MDSC）是最近发现的一种骨髓源性细胞类型，可用于治疗神经炎症性疾病。然而，这些细胞仅在炎症条件下由具有免疫抑制活性的未成熟骨髓细胞（IMC）形成，因此通常从患病动物中收集。然后，为了获得临床上更可行的来源，我们对直接源自健康骨髓的IMC进行了表征，并在体外证明了它们在病理条件下潜在的免疫抑制活性。然后，我们在人类小脑共济失调模型（浦肯野细胞变性（PCD）小鼠）中探索了它们的神经保护潜力，因为它表现出明确的神经退行性和神经炎症过程，而侵入性手术也会加剧这种过程。 IMCs 取自健康骨髓，并与活化的 T 细胞共培养。用Tag-it Violet分析后者的增殖和凋亡率。对于体内研究，通过立体定向手术将 IMC 移植到 PCD 小鼠的小脑中。我们还使用假手术动物以及未经治疗的动物作为手术效果的对照。通过转棒测试评估小鼠的运动行为。通过免疫组织化学测量浦肯野细胞密度，并通过 TUNEL 技术评估细胞死亡。我们还通过免疫荧光分析了小胶质细胞表型，并通过 qPCR 分析了炎症相关基因的表达模式。根据具体实验应用参数检验：单向或双向方差分析和学生 T 检验。 IMCs被证明在体外病理条件下能有效地获得免疫抑制活性，从而起到MDSCs的作用。就体内工作室而言，假手术 PCD 小鼠在运动协调、浦肯野细胞存活和小胶质细胞激活方面遭受了不利影响。将 IMC 颅内注射到 PCD 小鼠的小脑后，与未治疗的小鼠相比，在移植的动物中没有检测到特殊的益处。尽管如此，这种移植几乎完全防止了 PCD 小鼠手术造成的损伤，可能是通过调节炎症模式来实现的。我们的工作包括两个主要的转化发现：（1）IMCs可以直接使用，因为它们在病理条件下表现得像MDSCs，从而避免它们从患病受试者中收集； (2) IMCs 是神经外科手术中很有前途的辅助剂。