ERK介导的炎性反应参与肾缺血再灌注损伤

目的研究小鼠肾缺血再灌注损伤的发病机制。方法建立小鼠肾缺血再灌注损伤模型。12只雄性C57BL／6随机分为2个组（n=6）,分别为假手术组（Sham）,肾缺血再灌注损伤模型组（IRI）。IRI组血管夹夹闭左肾动脉,置于32℃温箱后1h松开血管夹,去除右肾。Sham组操作同上,但不夹闭左肾动脉。再灌注24h后处死小鼠,收集血清和肾脏标本。测定血清肌酐（Cr）和血尿素氮（BUN）。PAS染色后显微镜下观察肾脏形态学变化,Western印迹分析ERK、p-ERK的表达,PCR检测MCP-1、IFN-γ。结果与假手术组（Sham）相比,IRI组血清肌酐、血尿素氮明显升高,病理检查可见肾脏内肾小管上皮细胞明显肿胀坏死、蛋白管型形成明显,还可观察到炎性细胞浸润明显增加。ERK、p-ERKWestern印迹结果PCR显示MCP-1、TNF-α也明显上调,但ERK表达不变。结论在肾缺血再灌注中,ERK激活介导的炎性后府可能参与了肾扣伤。     

肾缺血再灌注损伤大鼠肾内AQP2表达水平降低

目的了解肾脏缺血再灌注损伤(ischemia reperfusion injury, IRI)时肾内水通道蛋白-2(aquaporin 2, AQP2)免疫组织化学表达特点。方法建立大鼠右侧肾IRI 45min模型,随机分为缺血再灌注1d、3d、5d、7d组和假手术1d组,检测尿常规、尿比重、尿素氮、血肌酐;HE染色观察肾脏病理形态学变化;免疫组织化学染色观察IRI时肾脏AQP2表达的变化。结果 IRI后,大鼠出现尿量增多,尿比重降低,血肌酐、尿素氮均增加;HE染色示右侧肾充血,水肿以及肾小管上皮细胞肿胀、坏死和脱落;免疫组织化学染色显示AQP2免疫反应性在右肾降低,左肾增强。肾组织的变化在第7d基本恢复正常。结论肾IRI时肾内AQP2表达降低,可能与IRI后尿量增多、尿比重降低相关。     

骨髓间充质干细胞移植修复大鼠半横断脊髓损伤

目的初步探讨骨髓间充质干细胞诱导为神经细胞,及其移植对大鼠脊髓半横断损伤神经功能恢复和运动的影响。方法贴壁培养法分离培养大鼠骨髓间充质干细胞(mesenchymal stem cells,MSCs),大鼠脊髓匀浆上清诱导第3代向神经细胞分化,经免疫组化鉴定分化后细胞的性质。制备大鼠半横断脊髓损伤模型,脊髓损伤局部注射BrdU标记诱导后的神经细胞。细胞移植5周后观察移植细胞在脊髓内存活分布情况。结果倒置显微镜下可见MSCs呈纺锤形和多角形,有1~2个核仁,经脊髓匀浆上清诱导后,发出数个细长突起,并交织成网,诱导后的细胞表达Nestin,可推测诱导后的细胞为MSCs源神经细胞。5周后移植的MSCs在宿主损伤脊髓内聚集并存活,表达MAP-2、NF、GFAP与对照组比较有统计学意义(P0.05)。大鼠运动功能较移植前有所改善。结论MSCs经脊髓匀浆上清诱导后移植治疗大鼠半横断脊髓损伤可使运动功能得到改善。     

骨髓间充质干细胞对移植肾缺血再灌注损伤保护作用的实验研究

目的 观察骨髓间充质干细胞（MSCs）对移植肾缺血再灌注损伤（IRI）模型修复的保护作用,及其作用机制的思路。方法 （1）采用密度梯度离心法结合贴壁分离法分离培养纯化SD大鼠骨髓MSCs,观察其形态,流式细胞仪检测细胞表面标记,检测骨髓MSCs向成骨和成脂细胞分化的潜能;（2）成年雌性SD大鼠28只,随机分组：正常对照组（control group,n=6）,假手术对照组（sham-operated group,n=6）,移植肾IRI组（vehicle-treated I/R group,n=8）,经尾静脉输注间充质干细胞（MSCs）移植肾IRI组（MSCs-treated via tail vein I/R group,n=8）。检测肾功能指标血尿素氮（BUN）和肌酐（Cr）水平变化,评定肾小管的凋亡指数和增殖指数,测定肾组织起氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）活性及微量丙二醛（MDA）水平,以及对肾脏病理学变化进行观察。结果 （1）分离培养的骨髓MSCs纯度高、生物学特征稳定;（2）移植肾IRI组肾功能指标（BUN36.9±4.8,Scr279.9±22.6）、氧化应激指标明显升高,组织形态学出现肾间质水肿明显,肾小管上皮细胞空泡样变性,近曲小管管壁肿胀,管腔变小。而经尾静脉输注MSCs移植肾IRI组大鼠肾功能指标（BUN22.6±7.8,Scr223.6±26.7）和氧化应激指标得到明显改善（P〈0.05）,组织形态学肾小管上皮细胞细胞核固缩、碎裂和溶解等细胞坏死和变性征象明显减轻,肾小管上皮细胞增殖指数（PI）高于IRI组,肾小管上皮细胞凋亡指数（AI）低于IRI组,两组间差异有统计学意义（P〈0.05）。结论 骨髓MSCs输注能促进肾脏IRI损伤后肾脏细胞增殖,抑制肾脏细胞凋亡,降低血清Creatinine和BUN,在一定程度上促进IRI后肾功能的恢复,通过抑制氧自由基的生成减轻肾组织的损伤程度,改善肾功能。     

人脐血间充质干细胞诱导分化为神经细胞的研究

目的探讨体外诱导人脐血间充质干细胞(MSCs)向神经细胞分化的条件,为治疗中枢神经系统损伤提供实用的干细胞来源。方法体外分离、纯化、扩增脐血MSCs,流式细胞仪检测细胞表面标志。采用脑源性神经营养因子BDNF 10ng/ml 维甲酸RA0.5μM 碱性成纤维生长因子bFGF 20ng/ml协同诱导脐血MSCs定向分化。免疫荧光染色检测诱导后细胞的星形胶质细胞特异标志GFAP及神经元特异标志MAP2的表达情况。建立大鼠脊髓横断损伤模型,将BrdU标记的诱导后的细胞移植入损伤的脊髓中,采用BBB运动功能评分标准在术后24h及1、2、3、4、5周各时间点对大鼠进行运动功能评分。用组织学和免疫组化方法检测移植到大鼠脊髓中的BrdU阳性细胞的存活、迁移、分化情况。结果脐血MSCs体外培养三代后,细胞表面CD11b、CD34、CD45和CD44表达阴性。诱导分化7d后,大部分细胞的形态类似神经元,免疫荧光染色检测MAP2阳性细胞占大多数,明显多于GFAP阳性细胞。5周后,细胞移植组大鼠的后肢运动功能恢复情况较对照组好。免疫组织化学结果显示植入的细胞可长时间在宿主脊髓中存活,并向损伤处两端迁移。结论人脐血MSCs于体外在特定的条件下可以诱导分化为神经元样细胞。移植脐血MSCs诱导后的神经细胞可在损伤的脊髓中存活、迁移,并能促进脊髓损伤后行为和功能恢复。     

Eritoran对大鼠肾脏缺血再灌注损伤的保护作用

目的:观察eritoran对大鼠肾脏缺血再灌注损伤模型的.方法:建立SD大鼠缺血再灌注模型,给予eritoran治疗而对照组给予生理盐水治疗,观察各组的肾功能情况、肾组织光镜病理,并采用核糖核酸酶保护测定检测肾组织炎症因子/趋化因子的表达.结果:与模型组相比,eritoran预处理可显著改善大鼠的肾功能,减轻缺血再灌注引起的肾小管损伤,减轻肾组织病变,减少肾组织单核细胞浸润并下调多种炎症因子的表达(TNF-α,IL-6,IL-1β和MCP-1).结论:本研究证实通过eritoran抑制Toll样受体4,可减轻大鼠肾脏缺血再灌注损伤中的炎症反应,减轻肾脏缺血再灌注损伤,eritoran可望成为肾脏I/R损伤的新治疗手段.     

应用小动物活体成像追踪观察EGFP标记的间充质干细胞

为探讨干细胞移植治疗过程中干细胞在体内的存活和迁移能力,利用非细胞损伤性的EGFP(enhanced green fl uorescence protein)标记间充质干细胞进行了实验研究。该研究用电穿孔方法将加强的绿色荧光蛋白表达质粒p CMV-EGFP(cytomegalovirus-EGFP plasmid)转染细胞产生具有EGFP标记的牙髓干细胞、皮肤成纤维细胞(skin fi broblast cells,SFCs)和脐带间充质干细胞。将EGFP标记的脐带间充质干细胞注射到裸鼠皮下,用小动物活体成像系统观察了EGFP标记细胞在体内移植后细胞存活能力和荧光强度随时间的变化情况。结果表明,电穿孔转染能够在体外产生高效表达EGFP的标记细胞,EGFP在牙髓干细胞、SFCs和脐带间充质干细胞中的表达率分别为80%、85%和80%。通过小动物活体成像系统检测表明,EGFP标记的脐带间充质干细胞注射到裸鼠皮下后EGFP荧光表达在7 d后逐渐下降,但免疫组化分析表明,移植细胞可存活6个月以上。该研究提示,EGFP标记的干细胞可用于体内追踪其存活、迁移及分化,为探讨干细胞移植治疗作用提供了实验证据。     

新型磷酸二酯酶5抑制剂CPD1对单侧肾缺血再灌注损伤后肾间质纤维化的影响

为观察新型磷酸二酯酶5 (phosphodiesterase 5, PDE5)抑制剂CPD1对单侧肾脏缺血再灌注损伤(unilateral renal ischemiareperfusion injury, UIRI)后肾间质纤维化的影响，本文采用夹闭(35 min) BALB/c小鼠肾蒂建立UIRI动物模型，造模2 h后每天给予CPD1 (5 mg/kg)灌胃治疗，术后第10天切除对侧肾脏，第11天取患侧肾脏。通过HE、Masson三色和天狼星红染色观察肾组织结构损伤和胶原沉积情况，利用免疫组织化学染色、蛋白质印迹技术分析肾脏组织、大鼠肾脏成纤维细胞(NRK-49F)、人肾小管上皮细胞(HK-2)中纤维化标志蛋白的表达。结果显示：与假手术组相比，UIRI小鼠肾脏中出现明显的肾小管上皮细胞损伤和间质纤维化，I型胶原(collagen I)、纤维连接蛋白(fibronectin)、纤溶酶原激活物抑制剂1型(plasminogen activator inhibitor-1, PAI-1)及α-平滑肌肌动蛋白(α-smooth muscle actin, α-SMA)表达显著增加；CPD1...     

绿色荧光蛋白标记人脐带间充质干细胞大鼠卵巢移植的实验观察

目的观察人脐带间充质干细胞(MSCs)移植于大鼠卵巢后存活的情况,为MSCs参与动物实验提供实验依据。方法以腺病毒介导绿色荧光蛋白(GFP)基因体外转染MSCs 48 h,于大鼠腹腔卵巢注射移植,于注射移植后1h及移植后3、7、21 d取材并在荧光显微镜下观察MSCs的存活情况。取材石蜡切片行苏木精-伊红(HE)染色观察移植细胞部位组织病理图像。结果 MSCs注射移植后3 d、7 d时GFP荧光表达较强,细胞轮廓清晰,与注射后1h平均吸光度值比较,移植后3、7 d检测荧光吸光度值差异均无统计学意义(P0.05);移植后21 d时GFP荧光表达较弱,吸光度值差异有统计学意义(P0.05)。术后大鼠组织切片光镜下移植的MSCs细胞清晰可见,无急性排斥反应特征出现。结论 MSCs在大鼠腹腔卵巢移植,其与异种个体组织相容性较好。     

建立对未分化细胞特异性标记的小鼠胚胎干细胞系

构建pRex-1-EGFP表达载体,电穿孔转染小鼠ES细胞,用增强绿色荧光蛋白对起源于3．5d胚泡内细胞团的小鼠胚胎干细胞进行特异性标记,用荧光显微观察EGFP的表达以及RT-PCR方法检测Rex-1基因在未分化和分化中ES细胞中的表达情况。结果显示,EGFP基因成功转入小鼠ES细胞,并在未分化的ES细胞中高效表达;细胞开始分化后,EGFP的表达开始下降。由Rex-1基因启动子控制下的EGFP稳定表达的小鼠ES细胞系,对哺乳动物早期发育过程的研究以及对筛选能够调节上述过程的小分子化合物具有重要意义。     

Bone-derived mesenchymal stromal cells from HIV transgenic mice exhibit altered proliferation,differentiation capacity and paracrine functions along with impaired therapeutic potential in kidney injury

Mesenchymal stem cells (MSCs) secrete paracrine factors that could be cytoprotective and serve roles in immunoregulation during tissue injury. Although MSCs express HIV receptors, and co-receptors, and are susceptible to HIV infection, whether HIV-1 may affect biological properties of MSCs needs more study. We evaluated cellular proliferation, differentiation and paracrine functions of MSCs isolated from compact bones of healthy control mice and Tg26 HIV-1 transgenic mice. The ability of MSCs to protect against cisplatin toxicity was studied in cultured renal tubular cells as well as in intact mice. We successfully isolated MSCs from healthy mice and Tg26 HIV-1 transgenic mice and found the latter expressed viral Nef, Vpu, NL4-3 and Vif genes. The proliferation and differentiation of Tg26 HIV-1 MSCs was inferior to MSCs from healthy mice. Moreover, transplantation of Tg26 HIV-1 MSCs less effectively improved outcomes compared with healthy MSCs in mice with acute kidney injury. Also, Tg26 HIV-1 MSCs secreted multiple cytokines, but at significantly lower levels than healthy MSCs, which resulted in failure of conditioned medium from these MSCs to protect cultured renal tubular cells from cisplatin toxicity. Therefore, HIV-1 had adverse biological effects on MSCs extending to their proliferation, differentiation, function, and therapeutic potential. These findings will help in advancing mechanistical insight in renal injury and repair in the setting of HIV-1 infection.     

Microvesicles derived from mesenchymal stem cells enhance survival in a lethal model of acute kidney injury

Several studies demonstrated that treatment with mesenchymal stem cells (MSCs) reduces cisplatin mortality in mice. Microvesicles (MVs) released from MSCs were previously shown to favor renal repair in non lethal toxic and ischemic acute renal injury (AKI). In the present study we investigated the effects of MSC-derived MVs in SCID mice survival in lethal cisplatin-induced AKI. Moreover, we evaluated in vitro the effect of MVs on cisplatin-induced apoptosis of human renal tubular epithelial cells and the molecular mechanisms involved. Two different regimens of MV injection were used. The single administration of MVs ameliorated renal function and morphology, and improved survival but did not prevent chronic tubular injury and persistent increase in BUN and creatinine. Multiple injections of MVs further decreased mortality and at day 21 surviving mice showed normal histology and renal function. The mechanism of protection was mainly ascribed to an anti-apoptotic effect of MVs. In vitro studies demonstrated that MVs up-regulated in cisplatin-treated human tubular epithelial cells anti-apoptotic genes, such as Bcl-xL, Bcl2 and BIRC8 and down-regulated genes that have a central role in the execution-phase of cell apoptosis such as Casp1, Casp8 and LTA. In conclusion, MVs released from MSCs were found to exert a pro-survival effect on renal cells in vitro and in vivo, suggesting that MVs may contribute to renal protection conferred by MSCs.     

Bioimaging for the monitoring of the in vivo distribution of infused mesenchymal stem cells in a mouse model of the graft-versus-host reaction

Cell therapy using MSCs (mesenchymal stem cells) might be effective treatment for refractory GVHD (graft-versus-host disease). However, the fate and distribution of MSCs after transplantation remains unclear. In this study, an animal model was developed to monitor the dynamic distribution of MSCs in mice with GVHD. A GVHD mouse model was established by transplanting C57BL/6 donor bone marrow cells and C57BL/6 EGFP (enhanced green fluorescent protein) splenocytes into lethally irradiated BALB/c nude recipient mice. Donor MSCs were obtained from MHC-identical C57BL/6 RFP (red fluorescent protein) mice and infused into the recipient mice on the same transplantation day. In vivo movement of the donor splenocytes (EGFP) and MSCs (RFP) were evaluated by measuring the biofluorescence (IVIS-Xenogen system). Donor splenocytes and MSCs reached the lungs first, and then the gastrointestinal tract, lymph nodes and skin, in that order; the transit time and localization site of these cells were very similar. In the recipient mouse with GVHD, the number of detectable cells declined with time, as assessed by biofluorescence imaging and confirmed by RT (real-time)-PCR. This bioimaging system might be useful for preclinical testing and the design of therapeutic strategies for monitoring the dynamic distribution of MSCs with GVHD.     

Haematopoietic lineage-committed bone marrow cells, but not cloned cultured mesenchymal stem cells, contribute to regeneration of renal tubular epithelium after HgCl 2 -induced acute tubular injury

Abstract.   Objective : Our previous studies have demonstrated that endogenous bone marrow cells (BMCs) contribute to renal tubular regeneration after acute tubular injury. The aim of this study was to examine which fraction of BMCs, haematopoietic lineage marrow cells (HLMCs) or mesenchymal stem cells (MSCs), are effective. Materials and methods : Six-week-old female mice were lethally irradiated and were transplanted with female enhanced green fluorescent protein-positive (GFP⁺), plastic non-adherent marrow cells (as a source of HLMCs) plus cloned cultured male GFP⁻ MSCs. Four weeks later, they were assigned into two groups: control mice with vehicle treatment and mice treated with HgCl₂. Tritiated thymidine was given 1 h before animal killing which occurred at intervals over 2 weeks. Kidney sections were stained for a tubular epithelial marker, cell origin indicated by GFP immunohistochemistry or Y chromosome in situ hybridization; periodic acid-Schiff staining was performed, and samples were subjected to autoradiography. One thousand consecutive renal tubular epithelial cells per mouse, in S phase, were scored as either female (indigenous) GFP⁺ (HLMC-derived) or male (MSC-derived). Results : Haematopoietic lineage marrow cells and MSCs stably engrafted into bone marrow and spleen, but only HLMC-derived cells, not MSCs, were found in the renal tubules and were able to undergo DNA synthesis after acute renal injury. A few MSCs were detected in the renal interstitium, but their importance needs to be further explored. Conclusion : Haematopoietic lineage marrow cells, but not cloned cultured MSCs, can play a role not only in normal wear-and-tear turnover of renal tubular cells, but also in repair after tubular injury.     

CD44 fucosylation on mesenchymal stem cell enhances homing and macrophage polarization in ischemic kidney injury

The lack of homing ability possibly reduces the healing potential of bone-marrow-derived mesenchymal stem cells (MSCs). Therefore, transforming native CD44 on MSCs into a hematopoietic cell E-/L-selectin ligand (HCELL) that possesses potent E-selectin affinity might enhance the homing and regenerative abilities of MSCs. Through fucosyltransferase VI (FTVI) transfection, MSCs were fucosylated on N-glycans of CD44 to become HCELL positive, thus interacting with E-selectin on injured endothelial cells. HCELL expression facilitated MSC homing in kidneys within 24 h after injury and reduced lung stasis. An in vitro adhesion assay revealed that transfection enhanced the association between MSCs and hypoxic endothelial cells. In mice treated with HCELL-positive MSCs, the injured kidneys exhibited clusters of homing MSCs, whereas MSCs were rarely observed in mouse kidneys treated with HCELL-negative MSCs. Most MSCs were initially localized at the renal capsule, and some MSCs later migrated inward between tubules. Most homing MSCs were in close contact with inflammatory cells without tubular transdifferentiation. Furthermore, HCELL-positive MSCs substantially alleviated renal injury, partly by enhancing the polarization of infiltrating macrophages. In conclusion, engineering the glycan of CD44 on MSCs through FTVI transfection might enhance renotropism and the regenerating ability of MSCs in ischemic kidney injury.     

Increased cellular senescence in the murine and human stenotic kidney: Effect of mesenchymal stem cells

Cell stress may give rise to insuperable growth arrest, which is defined as cellular senescence. Stenotic kidney (STK) ischemia and injury induced by renal artery stenosis (RAS) may be associated with cellular senescence. Mesenchymal stem cells (MSCs) decrease some forms of STK injury, but their ability to reverse senescence in RAS remains unknown. We hypothesized that RAS evokes STK senescence, which would be ameliorated by MSCs. Mice were studied after 4 weeks of RAS, RAS treated with adipose tissue‐derived MSCs 2 weeks earlier, or sham. STK senescence‐associated β‐galactosidase (SA‐β‐Gal) activity was measured. Protein and gene expression was used to assess senescence and the senescence‐associated secretory phenotype (SASP), and staining for renal fibrosis, inflammation, and capillary density. In addition, senescence was assessed as p16+ and p21+ urinary exosomes in patients with renovascular hypertension (RVH) without or 3 months after autologous adipose tissue‐derived MSC delivery, and in healthy volunteers (HV). In RAS mice, STK SA‐β‐Gal activity increased, and senescence and SASP marker expression was markedly elevated. MSCs improved renal function, fibrosis, inflammation, and capillary density, and attenuated SA‐β‐Gal activity, but most senescence and SASP levels remained unchanged. Congruently, in human RVH, p21+ urinary exosomes were elevated compared to HV, and only slightly improved by MSC, whereas p16+ exosomes remained unchanged. Therefore, RAS triggers renal senescence in both mice and human subjects. MSCs decrease renal injury, but only partly mitigate renal senescence. These observations support exploration of targeted senolytic therapy in RAS.     

In Vivo Tracking and Comparison of the Therapeutic Effects of MSCs and HSCs for Liver Injury

Background

Mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) have been studied for damaged liver repair; however, the conclusions drawn regarding their homing capacity to the injured liver are conflicting. Besides, the relative utility and synergistic effects of these two cell types on the injured liver remain unclear.

Methodology/Principal Findings

MSCs, HSCs and the combination of both cells were obtained from the bone marrow of male mice expressing enhanced green fluorescent protein(EGFP)and injected into the female mice with or without liver fibrosis. The distribution of the stem cells, survival rates, liver function, hepatocyte regeneration, growth factors and cytokines of the recipient mice were analyzed. We found that the liver content of the EGFP-donor cells was significantly higher in the MSCs group than in the HSCs or MSCs+HSCs group. The survival rate for the MSCs group was significantly higher than that of the HSCs or MSCs+HSCs group; all surpassed the control group. After MSC-transplantation, the injured livers were maximally restored, with less collagen than the controls. The fibrotic areas had decreased to a lesser extent in the mice transplanted with HSCs or MSCs+HSCs. Compared with mice in the HSCs group, the mice that received MSCs had better improved liver function. MSCs exhibited more remarkable paracrine effects and immunomodulatory properties on hepatic stellate cells and native hepatocytes in the treatment of the liver pathology. Synergistic actions of MSCs and HSCs were most likely not observed because the stem cells in liver were detected mostly as single cells, and single MSCs are insufficient to provide a beneficial niche for HSCs.

Conclusions/Significance

MSCs exhibited a greater homing capability for the injured liver and modulated fibrosis and inflammation more effectively than did HSCs. Synergistic effects of MSCs and HSCs were not observed in liver injury.     

Transforming growth factor-β1-overexpressing mesenchymal stromal cells induced local tolerance in rat renal ischemia/reperfusion injury

BackgroundRegulatory T cells (Tregs) suppress excessive immune responses and play a crucial protective role in acute kidney injury (AKI). The aim of this study was to examine the therapeutic potential of transforming growth factor (TGF)-β1-overexpressing mesenchymal stromal cells (MSCs) in inducing local generation of Tregs in the kidney after ischemia/reperfusion (I/R) injury.MethodsMSCs were transduced with a lentiviral vector expressing the TGF-β1 gene; TGF-β1-overexpressing MSCs (designated TGF-β1/MSCs) were then transfused into the I/R-injured kidney via the renal artery.ResultsMSCs genetically modified with TGF-β1 achieved overexpression of TGF-β1. Compared with green fluorescent protein (GFP)/MSCs, TGF-β1/MSCs markedly improved renal function after I/R injury and reduced epithelial apoptosis and subsequent inflammation. The enhanced immunosuppressive and therapeutic abilities of TGF-β1/MSCs were associated with increased generation of induced Tregs and improved intrarenal migration of the injected cells. Futhermore, the mechanism of TGF-β1/MSCs in attenuating renal I/R injury was not through a direct canonical TGF-β1/Smad pathway.ConclusionTGF-β1/MSCs can induce a local immunosuppressive effect in the I/R-injured kidney. The immunomodulatory activity of TGF-β1–modified MSCs appears to be a gateway to new therapeutic approaches to prevent renal I/R injury.     

Renoprotective Effect of Human Umbilical Cord–Derived Mesenchymal Stem Cells in Immunodeficient Mice Suffering from Acute Kidney Injury

It is unknown whether human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) can improve the renal function of patients suffering from acute kidney injury. Moreover, before beginning clinical trials, it is necessary to investigate this renoprotective effect of hUC-MSCs in a xenogeneic model of acute kidney injury. However, no previous studies have examined the application of hUC-MSCs to immunodeficient mice suffering from acute kidney injury. The objectives of this study were to examine whether hUC-MSCs could improve renal function in nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice suffering from acute kidney injury, and to investigate the mechanism(s) for hUC-MSCs to improve renal function in this xenogeneic model. Early (3 hr) and late (12 hr) administrations of hUC-MSCs (10⁶ cells) were performed via the external jugular vein into NOD-SCID mice suffering from either folic acid (FA) (250 mg/kg body weight) or vehicle. The results showed that early administration of hUC-MSCs improved the renal function of NOD-SCID mice suffering from FA-induced acute kidney injury, as evidenced by decreased serum urea nitrogen and serum creatinine levels, as well as a reduced tubular injury score. The beneficial effects of hUC-MSCs were through reducing apoptosis and promoting proliferation of renal tubular cells. These benefits were independent of inflammatory cytokine effects and transdifferentiation. Furthermore, this study is the first one to show that the reduced apoptosis of renal tubular cells by hUC-MSCs in this xenogeneic model is mediated through the mitochondrial pathway, and through the increase of Akt phosphorylation.     

Infusion of mesenchymal stem cells overexpressing GDNF ameliorates renal function in nephrotoxic serum nephritis

Nephrotoxic serum nephritis (NSN) is a well-established animal model of glomerulonephritis, a frequent clinical condition with a high mortality rate owing to the ineffectiveness of current therapies. Mesenchymal stem cells (MSCs) are adult stem cells with potential as novel therapies in regenerative medicine owing to the absence of allogenic rejection. Glial cell-derived neurotrophic factor (GDNF) acts as a morphogen in kidney development. The therapeutic effectiveness of bone marrow MSCs overexpressing GDNF (GDNF-MSCs) was evaluated in an NSN rat model. An adenoviral vector was used to transduce MSCs with GDNF and a green fluorescent protein reporter gene. Then, GDNF-MSCs were injected into NSN rats via the renal artery. The influence of GDNF on renal injury was assessed. The location of GDNF-MSCs in kidneys was detected using fluorescence microscopy, cells were counted, and kidney function was measured. Infusion of GNDF-MSCs enhanced the recovery of renal function in NSN rats. MSCs were detected in the kidney cortex after injection. Compared with control MSCs, GDNF-MSCs led to significantly better renal function and injury recovery in NSN rats. GDNF has a positive effect on MSC differentiation in renal tissue. Owing to their highly renoprotective capacity, GDNF-MSCs represent a possible novel cell-based paradigm for treatment of glomerulonephritis.