Exosomes from miRNA‐126‐modified endothelial progenitor cells alleviate brain injury and promote functional recovery after stroke

AimsWe previously showed that the protective effects of endothelial progenitor cells (EPCs)‐released exosomes (EPC‐EXs) on endothelium in diabetes. However, whether EPC‐EXs are protective in diabetic ischemic stroke is unknown. Here, we investigated the effects of EPC‐EXs on diabetic stroke mice and tested whether miR‐126 enriched EPC‐EXs (EPC‐EXs^miR126) have enhanced efficacy.MethodsThe db/db mice subjected to ischemic stroke were intravenously administrated with EPC‐EXs 2 hours after ischemic stroke. The infarct volume, cerebral microvascular density (MVD), cerebral blood flow (CBF), neurological function, angiogenesis and neurogenesis, and levels of cleaved caspase‐3, miR‐126, and VEGFR2 were measured on day 2 and 14.ResultsWe found that (a) injected EPC‐EXs merged with brain endothelial cells, neurons, astrocytes, and microglia in the peri‐infarct area; (b) EPC‐EXs^miR126 were more effective than EPC‐EXs in decreasing infarct size and increasing CBF and MVD, and in promoting angiogenesis and neurogenesis as well as neurological functional recovery; (c) These effects were accompanied with downregulated cleaved caspase‐3 on day 2 and vascular endothelial growth factor receptor 2 (VEGFR2) upregulation till day 14.ConclusionOur results indicate that enrichment of miR126 enhanced the therapeutic efficacy of EPC‐EXs on diabetic ischemic stroke by attenuating acute injury and promoting neurological function recovery.     

Central nervous system and peripheral cell labeling by vascular endothelial cadherin-driven lineage tracing in adult mice

Understanding the contribution of endothelial cells to the progenitor pools of adult tissues has the potential to inform therapies for human disease.To address whether endothelial cells transdifferentiate into non-vascular cell types,we performed cell lineage tracing analysis using transgenic mice engineered to express a fluorescent marker following activation by tamoxifen in vascular endothelial cadherin promoter-expressing cells(VEcad-CreERT2;B6 Cg-Gt(ROSA)26Sortm9(CAG-tdTomato)Hze).Activation of target-cell labeling following 1.5 months of ad libitum feeding with tamoxifen-laden chow in 4–5 month-old mice resulted in the tracing of central nervous system and peripheral cells that include:cerebellar granule neurons,ependymal cells,skeletal myocytes,pancreatic beta cells,pancreatic acinar cells,tubular cells in the renal cortex,duodenal crypt cells,ileal crypt cells,and hair follicle stem cells.As Nestin expression has been reported in a subset of endothelial cells,Nes-CreERT2 mice were also utilized in these conditions.The tracing of cells in adult Nes-CreERT2 mice revealed the labeling of canonical progeny cell types such as hippocampal and olfactory granule neurons as well as ependymal cells.Interestingly,Nestin tracing also labeled skeletal myocytes,ileal crypt cells,and sparsely marked cerebellar granule neurons.Our findings provide support for endothelial cells as active contributors to adult tissue progenitor pools.This information could be of particular significance for the intravenous delivery of therapeutics to downstream endothelial-derived cellular targets.The animal experiments were approved by the Boise State University Institute Animal Care and Use Committee(approval No.006-AC15-018)on October 31,2018.     

HIFα Regulates Developmental Myelination Independent of Autocrine Wnt Signaling

The developing CNS is exposed to physiological hypoxia, under which hypoxia-inducible factor α (HIFα) is stabilized and plays a crucial role in regulating neural development. The cellular and molecular mechanisms of HIFα in developmental myelination remain incompletely understood. A previous concept proposes that HIFα regulates CNS developmental myelination by activating the autocrine Wnt/β-catenin signaling in oligodendrocyte progenitor cells (OPCs). Here, by analyzing a battery of genetic mice of both sexes, we presented in vivo evidence supporting an alternative understanding of oligodendroglial HIFα-regulated developmental myelination. At the cellular level, we found that HIFα was required for developmental myelination by transiently controlling upstream OPC differentiation but not downstream oligodendrocyte maturation and that HIFα dysregulation in OPCs but not oligodendrocytes disturbed normal developmental myelination. We demonstrated that HIFα played a minor, if any, role in regulating canonical Wnt signaling in the oligodendroglial lineage or in the CNS. At the molecular level, blocking autocrine Wnt signaling did not affect HIFα-regulated OPC differentiation and myelination. We further identified HIFα–Sox9 regulatory axis as an underlying molecular mechanism in HIFα-regulated OPC differentiation. Our findings support a concept shift in our mechanistic understanding of HIFα-regulated CNS myelination from the previous Wnt-dependent view to a Wnt-independent one and unveil a previously unappreciated HIFα–Sox9 pathway in regulating OPC differentiation.SIGNIFICANCE STATEMENT Promoting disturbed developmental myelination is a promising option in treating diffuse white matter injury, previously called periventricular leukomalacia, a major form of brain injury affecting premature infants. In the developing CNS, hypoxia-inducible factor α (HIFα) is a key regulator that adapts neural cells to physiological and pathologic hypoxic cues. The role and mechanism of HIFα in oligodendroglial myelination, which is severely disturbed in preterm infants affected with diffuse white matter injury, is incompletely understood. Our findings presented here represent a concept shift in our mechanistic understanding of HIFα-regulated developmental myelination and suggest the potential of intervening with an oligodendroglial HIFα-mediated signaling pathway to mitigate disturbed myelination in premature white matter injury.     

Development and function of tissue resident macrophages in mice

Macrophages are important for tissue development, homeostasis as well as immune response upon injury or infection. For a long time they were only seen as one uniform group of phagocytes with a common origin and similar functions. However, this view has been challenged in the last decade and revealed a complex diversity of tissue resident macrophages. Here, we want to present the current view on macrophage development and tissue specification and we will discuss differences as well as common patterns between heterogeneous macrophage subpopulations.     

骨髓干细胞参与小鼠急性肾小管坏死修复的实验研究

【摘要】 目的 观察在生理和病理情况下,骨髓来源的干细胞(BMSC)能否分化成肾小管上皮细胞。 方法 绿色荧光蛋白(GFP)标记的C57BL/6转基因小鼠提供骨髓细胞。同种无荧光标记的C57BL/6小鼠100只分为正常对照组、全身照射组、缺血再灌注组、骨髓移植组、骨髓移植+缺血再灌注组。受体鼠的骨髓重建经血液常规检查和流式细胞仪检测确认,并采用荧光组织化学、免疫组织化学等方法观察绿色荧光标记的BMSC在受体鼠肾脏的分布及数量。 结果 全身致死剂量γ射线照射未造成小鼠肾脏组织结构和生理功能的明显改变。骨髓移植后第56、84天的受体鼠肾小管中有少量GFP阳性细胞的存在[(78.75±5.99)%、(79.58±4.60)%],激光共聚焦显微镜进一步证实这些细胞位于肾小管,并表达肾小管上皮细胞特异性的功能蛋白megalin。 结论 在生理和病理情况下,骨髓干细胞均可以向肾小管上皮细胞转分化,参与肾小管上皮细胞的更新,并且在急性肾小管坏死的病理条件下,骨髓干细胞的肾向转化率与肾脏受损程度有关。     

ITP患者T细胞对巨核细胞生成作用的影响

本文应用改良的血浆凝块技术和共培养系统研究特发性血小板减少性紫癜(ITP)患者T细胞在体外对异体骨髓巨核细胞生成作用的影响,以探讨ITP的发病机制。实验结果表明,从总体来看,ITP患者的T细胞当加到培养物中和靶细胞共培养时,对巨核系祖细胞集落形成单位(CFU-MK)的集落效应无明显的影响。其中三例PAIgG升高患者的T细胞对CFU-MK有不同程度的抑制作用。以上结果提示ITP的发病机制相当复杂。除体液免疫机制外,也有细胞免疫机制参与,T细胞或其亚群对巨核系祖细胞生成抑制在ITP的发病机制中可能起着一定的作用。     

脐血CD34~+细胞体外短期培养扩增研究

为寻找更有效的体外扩增脐血CD34 + 细胞的造血细胞因子组合 ,采集健康产妇脐带血 ,用免疫磁珠法分选CD34 + 细胞。采用SCF、FLT3 L、TPO和IL 34种具有早期作用的细胞因子的不同组合进行脐血CD34 + 细胞短期无血清液体培养 ,观察培养前后有核细胞、CD34 + 细胞、CD34 + /CD38- 细胞、CFU GEMM、CFU GM和BFU E数量的变化。结果在 3种不同的细胞因子组合中 ,同时应用SCF、FLT3 L、TPO和IL 34种细胞因子培养 7d的扩增效果最好。突出的发现是在这种条件下CD34 + /CD38- 细胞亚群达到平均 1 97.9倍的扩增效果。提示 :SCF、FLT3 L、TPO和IL 34种细胞因子是脐血CD34 + 细胞体外扩增理想的细胞因子组合     

急性冠脉综合征患者循环内皮祖细胞与炎性相关因子的研究

目的:探讨急性心肌梗死(AMI)、不稳定性心绞痛(UA)患者外周血中循环内皮祖细胞(EPCs)与炎性相关因子C反应蛋白质(CRP)、白细胞介素-6(IL-6)及肿瘤坏死因子-α(TNF-α)的相关性。方法:取AMI(25例)UA患者(28例)及健康体检者(对照组32例)静脉血,采用密度梯度离心法从外周血获得单个核细胞;激光共聚焦显微镜鉴定FITC-UEA-I和Dil-acLDL双染色阳性细胞为正在分化的EPCs,并在倒置荧光显微镜下计数;酶联免疫法检测各种炎性相关因子。结果:AMI组及UA组的EPCs数量和血清CRPI、L-6、TNF-α水平显著高于正常对照组。结论:AMI及UA患者EPCs数量增加与炎性相关因子增加有关。     

Liver regeneration in acute severe liver impairment: a clinicopathological correlation study.

BACKGROUND: Although normally quiescent, the adult mammalian liver possesses a great capacity to regenerate after different types of injury. Major players in the regeneration process are mature residual cells, including hepatocytes, cholangiocytes and stromal cells. However, if the regenerative capacity of mature cells is impaired, hepatic progenitor cells (HPCs) are activated and expand into the liver parenchyma. Upon transit amplification, the progenitor cells generate new hepatocytes and biliary cells to restore liver homeostasis. AIMS/METHODS: To study the relationship between different histopathological parameters as well as their correlations with clinical parameters and outcome, we examined liver specimens from 74 patients with acute or subacute severe liver impairment by immunohistochemistry for CK7/CK19 (evaluation of HPCs activation/differentiation), Mib1(Ki 67)/P21 (evaluation of proliferative activity/proliferation arrest of hepatocytes) and hematoxylin and eosin (evaluation of hepatocyte loss). RESULTS: Of the 74 patients, 32% survived without transplantation, 14% died without transplantation and 54% were transplanted. Our results show that a threshold of 50% loss of hepatocytes, associated with significant decrease in the proliferative activity of remaining mature hepatocytes, is needed for extensive hepatic progenitor cell activation. Such activation is a sign of disease severity and occurs early (within 1 week) in the disease course. However, development of intermediate hepatocytes, suggesting HPCs differentiation towards mature hepatocytes, takes at least 1 week's time. We found a positive correlation between histopathological parameters (percentage hepatocyte loss, number of proliferating hepatocytes and number of HPCs) and clinical parameters of liver impairment such as model for end stage liver diseases (MELD). Surviving patients compared with those who either died or were transplanted had significantly less hepatocyte loss, less HPCs activation and more mature hepatocyte proliferative activity. Hepatocyte proliferative activity and degree of hepatocyte loss were the most important independent histopathological parameters in predicting outcome. CONCLUSION: Liver biopsy can provide important additional information in a patient with severe acute liver impairment.