Time-varying characteristics of the induced membrane and its effects on bone defect repair

PurposeThis study intended to determine the properties of induced membranes after various periods of polymethyl methacrylate (PMMA) retention and the effect of different retention intervals on subsequent defect repair.MethodsModel of a critical bone defect in rabbits was prepared to obtain the induced membrane. For varying intervals of spacer insertion (2, 4, 6, 8, 12, 16, and 20 weeks postoperatively), angiogenesis, osteogenesis, and MSC-related properties were analyzed by immunohistochemistry and western-blot. Furthermore, 2, 4, 6, and 8 weeks after PMMA insertion, bone grafting was performed. Characteristics of defect repair were analyzed by X-ray and micro-CT analysis.ResultsThe induced membrane displayed angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. Quantitation of protein expression (RUNX2, ALP, VEGF, TGF-beta, OCT4, and STRO1) revealed that selected proteins gradually rose to a high level at 4–8 weeks postoperatively and then decreased to a low level over a long time period. Following bone grafting, the most new bone formation was in the group when grafting was performed at 4 weeks, followed by the groups at 2 and 6 weeks, with the least in the group at 8 weeks.ConclusionThe induced membrane displays angiogenesis, osteogenesis, and MSC-related properties from the 2- to 20-week intervals. These were increased to a peak level at 4–8 weeks postoperatively and then gradually decreased. The optimal timing for bone grafting at the second stage in the presented model was 4 weeks after PMMA insertion.     

Efficacy of stem cell-based therapies for colistin-induced nephrotoxicity

The increase in infections with multidrug resistant bacteria has forced to return to the use of colistin, antibiotic with known nephrotoxicity. Mesenchymal stem cells (MSCs) are being extensively investigated for their potential in regenerative medicine. This study aimed to investigate the possible protective mechanisms of the MSCs against kidney injury induced by colistin. Forty adult female albino rats were randomly classified into 4 equal groups; the control group, the MSC-treated group (a single dose of 1 ×10⁶ /ml MSCs through the tail vein), the colistin-treated group (36 mg/kg/day colistin was given for 7 days), and the both colistin and MSC group (36 mg/kg/day colistin and 1 ×10⁶ /ml MSCs). Main outcome measures were histopathological alterations, kidney malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and immunohistological autophagy evaluation. MSC repressed the progression of colistin-induced kidney injury as evidenced by the improvement of histopathological alterations and the substantial increase MDA, and decrease SOD and CAT in serum levels. Moreover, MSC resulted in a profound reduction in oxidative stress as manifested by decreased MDA and increased SOD in serum. Notably, MSC suppressed colistin-induced autophagy; it reduced renal levels of Beclin-1, P62 and LC3A/B. Furthermore, MSC decreased renal levels of eNOS. Lastly, MSC efficiently decreased expression of the TUNEL positive cell number. MSC confers protection against colistin-induced kidney injury by alleviating oxidative stress, nitric oxide synthase besides modulating reducing autophagy and apoptosis.     

Efficient polymer nanoparticle-mediated delivery of gene editing reagents into human hematopoietic stem and progenitor cells

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脑胶质瘤干细胞衍生的外泌体lncRNA HOXA-AS2促进脑胶质瘤的增殖、迁移、侵袭和干细胞特性

背景与目的：外泌体是介导肿瘤微环境中肿瘤细胞与受体细胞间相互作用的重要信使。然而，细胞外泌体长链非编码RNA（long non-coding RNA，lncRNA）在脑胶质瘤干细胞（glioma stem cell，GSC）和脑胶质瘤细胞的细胞间通信中的作用尚不清楚。本研究探究外泌体衍生的lncRNA对脑胶质瘤增殖、迁移、侵袭和干细胞特性的影响。方法：从中国脑胶质瘤基因组图谱（the Chinese Glioma Genome Atlas，CGGA）和癌症基因组图谱（the Cancer Genome Atlas，TCGA）数据库下载包含低级别脑胶质瘤（low-grade glioma，LGG）和高级别脑胶质瘤（high-grade glioma，HGG）lncRNA表达数据的数据集，识别LGG和HGG组织之间的差异表达lncRNA（differentially expressed lncRNA，DelncRNA），并分析HOXA-AS2水平与胶质瘤患者总生存期（overall survival，OS）之间的关系。从人胶质瘤细胞系SHG44中分离GSC，用流式细胞术检测CD133⁺富集的细胞，再用蛋白质印迹法（Western blot）检测干细胞相关蛋白（CD133、SOX2和OCT4）的表达水平。提取和识别SHG44-GSC衍生的外泌体，并用PKH26细胞膜染料进行荧光标记；再将转染了Cy3标记HOXA-AS2的SHG44-GSC与SHG44细胞进行间接共培养；后用实时荧光定量聚合酶链反应（real-time fluorescence quantitative polymerase chain reaction，RTFQ-PCR）检测SHG44-GSC和SHG44-GSC衍生外泌体中HOXA-AS2的水平。使用pLVX-IRES-PURO HOXA-AS2慢病毒质粒和含靶向HOXA-AS2质粒的慢病毒shRNA进行慢病毒转染。采用细胞计数试剂盒-8（cell counting kit-8，CCK-8）和transwell实验检测SHG44-GSC衍生的外泌体HOXA-AS2对SHG44细胞增殖和侵袭能力的影响。结果：HOXA-AS2在胶质瘤中呈现高表达，且与患者较差的OS相关（P<0.01）。SHG44-GSC中CD133⁺细胞比例明显高于SHG44细胞（P<0.000 1），SHG44-GSC中干细胞相关蛋白（CD133、SOX2和OCT4）的表达水平明显高于亲代SHG44细胞（P<0.000 1），并且SHG44-GSC中HOXA-AS2水平显著升高（P<0.000 1）。PKH26标记的外泌体被SHG44细胞吸收，且SHG44细胞中可观察到Cy3标记的HOXA-AS2；HOXA-AS2 OE转染的SHG44-GSC细胞（SHG44-GSC/HOXA-AS2 OE）和SHG44-GSC/HOXA-AS2 OE衍生的外泌体（SHG44-GSC/HOXA-AS2 OE-Exo）中HOXA-AS2水平显著升高（P<0.01），在与SHG44-GSC/HOXA-AS2 OE细胞共培养的SHG44细胞中HOXA-AS2水平显著升高（P<0.01）。SHG44-GSC/HOXA-AS2 OE-Exo可显著促进SHG44细胞增殖、迁移和侵袭。结论：来自SHG44-GSC的外泌体HOXA-AS2能显著促进胶质瘤细胞增殖、迁移、侵袭和干细胞特性，提示HOXA-AS2可能是脑胶质瘤潜在的治疗靶点。     

Genetic modification of scAAV‐equine‐BMP‐2 transduced bone‐marrow‐derived mesenchymal stem cells before and after cryopreservation: An “off‐the‐shelf” option for fracture repair

Optimizing the environment of complex bone healing and improving treatment of catastrophic bone fractures and segmental bone defects remains an unmet clinical need both human and equine veterinary medical orthopaedics. The objective of this study was to determine whether scAAV‐equine‐BMP‐2 transduced cells would induce osteogenesis in equine bone marrow derived mesenchymal stem cells (BMDMSCs) in vitro, and if these cells could be cryopreserved in an effort to osteogenically prime them as an “off‐the‐shelf” gene therapeutic approach for fracture repair. Our study found that transgene expression is altered by cell expansion, as would be expected by a transduction resulting in episomal transgene expression, and that osteoinductive levels could still be achieved 5 days after recovery, and protein expression would continue up to 14 days after transduction. This is the first evidence that cryopreservation of genetically modified BMDMSCs would not alter the osteoinductive potential or clinical use of allogeneic donor cells in cases of equine fracture repair. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1310–1317, 2019.     

Platelets are important for the development of immune tolerance: Possible involvement of TGF‐β in the mechanism

Platelets have diverse roles in immune processes in addition to their key functions in haemostasis and thrombosis. Some studies imply that platelets may be possibly related to the immune tolerance induction. However, the role of platelets in the development of immune tolerance is not fully understood. The purpose of this study was to investigate the role of platelets in the development of regulatory mechanisms responsible for cutaneous inflammation using a mouse model of low zone tolerance (LZT). Mice were treated with 2,4,6‐trinitro‐1‐chlorobenzene (TNCB) 8 times every other day for tolerance induction with administration of anti‐platelet antibody or control antibody during the tolerance induction phase every 3 days. After the treatment for the tolerance induction, mice were sensitized and then challenged with TNCB. The contact hypersensitivity (CHS) was significantly decreased at 24 hours after challenge in the mice with LZT than in those without LZT. Platelet depletion via administration of anti‐platelet antibody reversed the inhibition of CHS and reduced the frequency of Foxp3⁺ Tregs in the inflamed skin and draining lymph nodes in mice with LZT. In addition, repeated low‐dose skin exposure resulted in elevated plasma levels of transforming growth factor (TGF)‐β1. Interestingly, platelet depletion reduced plasma TGF‐β1 levels of mice with LZT. Furthermore, the CHS response was reduced by administration of recombinant TGF‐β1 during platelet depletion in mice with LZT. Administration of anti‐TGF‐β antibody reversed the inhibition of the CHS responses. These results suggest that platelets are involved in the induction of immune tolerance via the release of TGF‐β1.     

Insights into the pathogenesis of ATP1A1‐related CMT disease using patient‐specific iPSCs

The development of patient‐specific induced pluripotent stem cells (iPSCs) offered interesting insights in modeling the pathogenesis of Charcot‐Marie‐Tooth (CMT) disease and thus we decided to explore the phenotypes of iPSCs derived from a single CMT patient carrying a mutant ATP1A1 allele (p.Pro600Ala). iPSCs clones generated from CMT and control fibroblasts, were induced to differentiate into neural precursors and then into post‐mitotic neurons. Control iPSCs differentiated into neuronal precursors and then into post‐mitotic neurons within 6‐8 days. On the contrary, the differentiation of CMT iPSCs was clearly defective. Electrophysiological properties confirmed that post‐mitotic neurons were less mature compared to the normal counterpart. The impairment of in vitro differentiation of CMT iPSCs only concerned with the neuronal pathway, because they were able to differentiate into mesendodermal cells and other ectodermal derivatives. ATP1A1 was undetectable in the few neuronal cells derived from CMT iPSCs. ATP1A1 gene mutation (p.Pro600Ala), responsible for a form of axonal CMT disease, is associated in vitro with a dramatic alteration of the differentiation of patient‐derived iPSCs into post‐mitotic neurons. Thus, the defect in neuronal cell development might lead in vivo to a decreased number of mature neurons in ATP1A1‐CMT disease.     

Efectos funcionales e histológicos posteriores al implante de células madre pluripotentes en un modelo murino con esfinterotomía

Introduction and aimsFecal incontinence is a disabling condition with devastating consequences for the patients. Medical and surgical options are not very satisfactory, reason by which regenerative medicine has been considered in this field. In the present research, we analyzed functional and histologic effects after implanting pluripotent stem cells (PSCs) in a murine model with sphincterotomy.Materials and methodsFemale Wistar rats were subjected to sphincterotomy and divided into three groups. Group 1 (control group) was treated with 300 μL of balanced saline solution and group 2 (late treatment) and group 3 (early treatment) received 50,000 PSCs resuspended in 300 μL of balanced saline solution. All animals were evaluated through high-resolution anorectal manometry 24 hours before and after sphincterotomy and every month for three months. Finally, the rats were euthanized and histopathologic sections from the anal canal were obtained.ResultsAll groups showed a decrease in resting anal pressure and squeeze anal pressure 24 hours after sphincterotomy. At the third month, higher anal pressures in the groups treated with PSCs were detected. Regarding the histologic effects, the microscopic architecture was restored and there was a significant decrease in the inflammatory response in the groups treated with PSCs.ConclusionPSCs implantation improves anal tone, as well as histologic structure, presenting better regenerative results when implanted as early treatment.     

人髌下脂肪垫干细胞的分离培养鉴定及初步研究

目的建立人髌下脂肪垫干细胞分离、培养和鉴定的平台，验证其可作为可靠的干细胞来源，并可作为细胞模型参与科学研究。 方法人髌下脂肪垫取自膝关节置换手术患者，经Ⅰ型胶原酶消化，在高糖Dulbecco改良Eagle培养基(DMEM)内扩增，取P5代细胞用于检测其"干性"及三向分化能力。与微尺度支架结合，通过RT－PCR检测成骨基因的表达，应用最小显著性差异法进行组间两两比较，用于验证微尺度支架的成骨诱导特性。 结果人髌下脂肪垫干细胞具备间充质干细胞相关特性，包括黏附贴壁性；成脂肪、成软骨及成骨分化；表达相关表面标记，如分化抗原簇(CD)73、CD90和CD105；不表达造血细胞系的分子表面标记，如c-kit、CD14、CD11b、CD34、CD45、CD19、CD79和人白细胞抗原(HLA)-DR。本课题中人髌下脂肪垫来源干细胞成功作为一种干细胞模型，证明HaCG微尺度支架具备成骨诱导特性，表现为三组中成骨基因ALP、COL1、Runx2表达差异有统计学意义(分别为F＝150，P<0.01；F＝68，P<0.01；F＝16，P<0.01)。HaCG微尺度支架组高于纯明胶微尺度支架组及二维培养组，纯明胶微尺度支架组高于二维培养组(P值均小于0.05)。 结论人髌下脂肪垫干细胞分离、培养和鉴定平台的建立，未来可作为细胞模型应用于多种不同实验。