Potential of human induced pluripotent stem cells differentiating into corneal epithelial cells in simulated limbal stem cell microenvironment / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the potential of human induced pluripotent stem cells(hiPSCs)differentiating into corneal epithelial cells in the simulated limbal stem cells(LSCs)microenvironment.METHODS: The hiPSC cell lines were established in vitro, and hiPSCs were co-cultured with corneal stromal cells in transwell system, which simulated the LSC microenvironment. Bone morphogenetic protein 4(BMP4)and a specific transforming growth factor β inhibitor(SB431542)were added to improve the differentiation efficacy. The expression of corneal epithelial cell-specific markers CK3 and CK12, corneal epithelial cell precursor CK15, and the limbal stem cell markers ABCG5 were determined by immunofluorescence staining and flow cytometry.RESULTS: The hiPSCs were actively proliferated in vitro, and immunofluorescence staining showed positive stem cell-specific markers OCT4, SOX2, TRA-1-60 and NANOG. Furthermore, hiPSCs co-cultured with corneal stromal cells exhibited LSCs markers ABCG5 and corneal epithelial cell precursor markers CK15 were positive; however, corneal epithelial cell markers CK3 and CK12 were negative. With the addition of BMP4 and SB431542, hiPSCs showed positive expression of CK3, and the CK3 expression increased over the time.CONCLUSION: With the addition of SB431542 and BMP4, hiPSCs cultured in simulated LSCs microenvironment could differentiate into corneal epithelial cells.

Construction of iPSC-derived Inhibitory Neural Network Tissue with Synaptic Transmission Potentials / 中山大学学报(医学科学版)

ObjectiveDirected differentiation of human induced pluripotent stem cells （hiPSCs） into spinal cord γ-aminobutyric acid （GABA）-ergic progenitor cells were implanted into an decellularized optical nerve （DON） bioscaffold to construct a hiPSC-derived inhibitory neural network tissue with synaptic activities. This study aimed to provide a novel stem cell-based tissue engineering product for the study and the repair of central nervous system injury. MethodsThe combination of stepwise directional induction and tissue engineering technology was applied in this study. After hiPSCs were directionally induced into human neural progenitor cells （hNPCs） in vitro， they were seeded into a DON for three-dimensional culture， allowing further differentiation into inhibitory GABAergic neurons under the specific neuronal induction environment. Transmission electron microscopy and whole cell patch clamp technique were used to detect whether the hiPSCs differentiated neurons could form synapse-like structures and whether these neurons had spontaneous inhibitory postsynaptic currents， respectively， in order to validate that the hiPSC-derived neurons would form neural networks with synaptic transmission potentials from a structural and functional perspective. ResultsThe inhibitory neurons of GABAergic phenotype were successfully induced from hiPSCs in vitro， and maintained good viability after 28 days of culture. With the transmission electron microscopy， it was observed that many cell junctions were formed between hiPSC-derived neural cells in the three-dimensional materials， some of which presented a synapse- like structure， manifested as the slight thickness of cell membrane and a small number of vesicles within one side of the cell junctions， the typical structure of a presynatic component， and focal thickness of the membrane of the other side of the cell junctions， a typical structure of a postsynaptic component. According to whole-cell patch-clamp recording， the hiPSC-derived neurons had the capability to generate action potentials and spontaneous inhibitory postsynaptic currents were recorded in this biotissue. ConclusionsThe results of this study indicated that hiPSCs can be induced to differentiate into GABAergic progenitor cells in vitro and can successfully construct iPSC-derived inhibitory neural network tissue with synaptic transmission after implanted into a DON for three-dimensional culture. This study would provide a novel neural network tissue for future research and treatment of central nervous system injury by stem cell tissue engineering technology.

Development of porcine induced pluripotent stem cells with a CD163 reporter system / 生物工程学报

As main recipient cells for porcine reproductive and respiratory syndrome virus (PRRSV), porcine alveolar macrophage (PAM) are involved in the progress of several highly pathogenic virus infections. However, due to the fact that the PAM cells can only be obtained from primary tissues, research on PAM-based virus-host interactions remains challenging. The improvement of induced pluripotent stem cells (iPSCs) technology provides a new strategy to develop IPSCs-derived PAM cells. Since the CD163 is a macrophage-specific marker and a validated receptor essential for PRRSV infection, generation of stable porcine induced pluripotent stem cells lines containing CD163 reporter system play important roles in the investigation of IPSCs-PAM transition and PAM-based virus-host interaction. Based on the CRISPR/Cas9- mediated gene editing system, we designed a sgRNA targeting CD163 locus and constructed the corresponding donor vectors. To test whether this reporter system has the expected function, the reporter system was introduced into primary PAM cells to detect the expression of RFP. To validate the low effect on stem cell pluripotency, we generated porcine iPSC lines containing CD163 reporter and assessed the pluripotency through multiple assays such as alkaline phosphatase staining, immunofluorescent staining, and EdU staining. The red-fluorescent protein (RFP) expression was detected in CD163-edited PAM cells, suggesting that our reporter system indeed has the ability to reflect the expression of gene CD163. Compared with wild-type (WT) iPSCs, the CD163 reporter-iPSCs display similar pluripotency-associated transcription factors expression. Besides, cells with the reporter system showed consistent cell morphology and proliferation ability as compared to WT iPSCs, indicating that the edited-cells have no effect on stem cell pluripotency. In conclusion, we generated porcine iPSCs that contain a CD163 reporter system. Our results demonstrated that this reporter system was functional and safe. This study provides a platform to investigate the iPS-PAM development and virus-host interaction in PAM cells.

Advances in application of induced pluripotent stem cells in childhood genetic diseases / 中国生物制品学杂志

@#Somatic cell reprogramming has developed rapidly in the field of modern biology. Induced pluripotent stem cells(iPSCs)obtained through somatic cell reprogramming are not only capable of self-renewal,but also have multidirectional differentiation potential,which plays an important role in disease modeling and regenerative medicine. This paper reviewed the gene reprogramming technology,the disease models of iPSCs and the application prospects of iPSCs in childhood genetic diseases,so as to provide a reference for the application of iPSCs in the research of mechanism and treatment of various genetic diseases.

Effect of CDM3 on the co-culture of human induced pluripotent stem cells with matrigel-coated polycaprolactone to make cardiac patch / 中国胸心血管外科临床杂志

@#Objective    To provide experimental data and theoretical support for further studying the maturity of cardiac patches in other in vitro experiments and the safety in other in vivo animal experiments, through standard chemically defined and small molecule-based induction protocol (CDM3) for promoting the differentiation of human induced pluripotent stem cells (hiPSCs) into myocardium, and preliminarily preparing cardiac patches. Methods    After resuscitation, culture and identification of hiPSCs, they were inoculated on the matrigel-coated polycaprolactone (PCL). After 24 hours, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and the stemness of hiPSCs was identified by OCT4 fluorescence. After fixation, electron microscope scanning was performed to observe the cell morphology on the surface of the patch. On the 1st, 3rd, 5th, and 7th days of culture, the cell viability was determined by CCK-8 method, and the growth curve was drawn to observe the cell growth and proliferation. After co-cultured with matrigel-coated PCL for 24 hours, hiPSCs were divided into a control group and a CDM3 group, and continued to culture for 6 days. On the 8th day, the cell growth was observed by DAPI fluorescence under a fluorescence microscope, and hiPSCs stemness was identified by OCT4 fluorescence, and cTnT and α-actin for cardiomyocyte marker identification. Results    Immunofluorescence of hiPSCs co-cultured with matrigel-coated PCL for 24 hours showed that OCT4 emitted green fluorescence, and hiPSCs remained stemness on matrigel-coated PCL scaffolds. DAPI emitted blue fluorescence: cells grew clonally with uniform cell morphology. Scanning electron microscope showed that hiPSCs adhered and grew on matrigel-coated PCL, the cell outline was clearly visible, and the morphology was normal. The cell viability assay by CCK-8 method showed that hiPSCs proliferated and grew on PCL scaffolds coated with matrigel. After 6 days of culture in the control group and the CDM3 group, immunofluorescence showed that the hiPSCs in the control group highly expressed the stem cell stemness marker OCT4, but did not express the cardiac markers cTnT and α-actin. The CDM3 group obviously expressed the cardiac markers cTnT and α-actin, but did not express the stem cell stemness marker OCT4. Conclusion    hiPSCs can proliferate and grow on matrigel-coated PCL. Under the influence of CDM3, hiPSCs can be differentiated into cardiomyocyte-like cells, and the preliminary preparation of cardiac patch can provide a better treatment method for further clinical treatment of cardiac infarction.

Establishment and characterization of high-throughput culture platform for kidney organoids / 中华肾脏病杂志

Objective:To establish and identify a high-throughput culture platform for induced pluripotent stem cells to differentiated kidney organoids.Methods:Human urine-derived induced pluripotent stem cells were selected and plated at a suitable cell density, and differentiated using small molecule compounds such as CHIR99021/fibroblast growth factor 9/heparin during day 1-6. On day 7, cells with appropriate density were digested and resuspended, than added to a 96-well 3D culture plate for 24 hours. After the cells formed spheroids, fibroblast growth factor 9 and heparin were added to induce differentiation till day 24. The immunofluorescence and transmission electron microscopy were used to compare the differences of kidney organoids obtained by the reported differentiation protocol (transwell protocol) method and high-throughput culture platform.Results:Kidney organoids were successfully differentiated by two protocols. Immunofluorescence results showed that LTL, GATA-3, and synaptopodin, which were major kidney cell markers, were all expressed, and mature renal organoids were formed. The results of transmission electron microscopy showed that the kidney organoids successfully developed foot processes, the unique cellular feature of the glomerular podocytes, which were evenly distributed and neatly interspersed with each other. At the same intermediate mesodermal cell count of 1.0×10 7, approximately 7 renal organoids were obtained by the transwell protocol, while approximately 1 000 renal organoids were obtained by the high-throughput culture platform. Conclusion:A high-throughput culture platform for kidney organoids is successfully established, and a large amount of mature kidney organoids with complete structure and function can be obtained. The differentiation efficiency of kidney organoids is greatly improved.

Establishment and application of hepatic organoid model of hepatitis B virus infection / 中华传染病杂志

Objective:To establish the hepatic organoid of hepatitis B virus (HBV) infection on the basis of induced pluripotent stem cells (iPSC) and an inverted colloidal crystal polyethylene glycol scaffold (ICC), and to evaluate the antiviral effect of nucleoside drugs.Methods:iPSC was differentiated into hepatocyte-like cells (HLC), and inoculated into ICC to construct a hepatic organoid. The relative mRNA expressions of Nanog homeobox (NANOG), sex determining region Y-box (SOX) 2, SOX17, forkhead box protein A2 (FOXA2), alpha fetoprotein (AFP) and albumin (ALB) were detected by real time quantitative polymerase chain reaction (RT-qPCR). Confocal laser microscopy was used to photograph the three-dimension (3D) structure of organs. The expression of sodium taurocholate cotransporting polypeptide (NTCP) in HLC was analyzed by Western blot and immunofluorescence. HepG2.2.15 cells were used to extract HBV virus particles to infect hepatic organoid. The relative expression of HBV pregenome RNA (pgRNA) in cells was detected by RT-qPCR. The expressions of hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg) in cytoplasm were observed under confocal laser microscopy. A total of 0.5 μmol/L entecavir and 0.5 μmol/L lamivudine were used to treat the infected cells respectively. The relative expression of HBV pgRNA in infected and uninfected cells was detected by RT-qPCR. Independent sample t test and one-way analysis of variance were used for statistical analysis. Results:Within 21 days of iPSC differentiation, the mRNA expressions of NANOG and SOX2 in stem cells markers decreased ( F=158.90 and 8.31, respectivley; P<0.001 and P=0.002, respectively), while the mRNA expressions of SOX17 and FOXA2 in the endoderm increased first and then decreased ( F=37.23 and 82.57, respectively, both P<0.001). In the later stage of differentiation, the mRNA expressions of AFP and ALB in liver cells increased ( F=4.65 and 34.64, respectively, P=0.012 and P<0.001, respectively), and all differences were statistically significant. NTCP was highly expressed in differentiated cells detected by Western blot and fluorescence microscopy, the protein expression level was 0.803±0.099. Confocal laser microscopy confirmed that the differentiated cells expressed ALB and presented spherical structure in ICC. The expression of HBV pgRNA and the immunostaining of HBsAg and HBcAg confirmed that HBV successfully infected hepatic organoid. Three days after the application of entecavir and lamivudine, the HBV pgRNA level decreased significantly both in entecavir group (0.665±0.220) and lamivudine group (0.503±0.117) compared to the uninfected cells (3.347±0.454), and the differences were both statistically significant ( t=10.53 and 12.72, respectively, both P<0.001). Conclusions:HLC display hepatic specific genes ALB and NTCP. Hepatic organoids constructed with iPSC and ICC have human liver function and can be infected by HBV. Entecavir and lamivudine could effectively inhibit the replication of HBV in hepatic organoids.

Directed differentiation of human induced pluripotent stem cells into midbrain / 南方医科大学学报

OBJECTIVE@#To establish an efficient protocol for directed differentiation of human induced pluripotent stem cells (hiPSCs) into functional midbrain dopaminergic progenitor cells (DAPs) in vitro.@*METHODS@#hiPSCs were induced to differentiate into DAPs in two developmental stages. In the first stage (the first 13 days), hiPSCs were induced into intermediate cells morphologically similar to primitive neuroepithelial cells (NECs) in neural induction medium containing a combination of small molecule compounds. In the second stage, the intermediate cells were further induced in neural differentiation medium until day 28 to obtain DAPs. After CM-DiI staining, the induced DAPs were stereotactically transplanted into the right medial forebrain bundle (MFB) of rat models of Parkinson's disease (PD). Eight weeks after transplantation, the motor behaviors of PD rats was evaluated. Immunofluorescence assay of brain sections of the rats was performed at 2 weeks after transplantation to observe the survival, migration and differentiation of the transplanted cells in the host brain microenvironment.@*RESULTS@#hiPSCs passaged stably on Matrigel showed a normal diploid karyotype, expressed the pluripotency markers OCT4, SOX2, and Nanog, and were positive for alkaline phosphatase. The primitive neuroepithelial cells obtained on day 13 formed dense cell colonies in the form of neural rosettes and expressed the neuroepithelial markers (SOX2, Nestin, and PAX6, 91.3%-92.8%). The DAPs on day 28 highly expressed the specific markers (TH, FOXA2, LMX1A and NURR1, 93.3-96.7%). In rat models of PD, the hiPSCs-DAPs survived and differentiated into TH+, FOXA2+ and Tuj1+ neurons at 2 weeks after transplantation. Eight weeks after transplantation, the motor function of PD rats was significantly improved as shown by water maze test (P < 0.0001) and apomorphine-induced rotation test (P < 0.0001) compared with rats receiving vehicle injection.@*CONCLUSION@#HiPSCs can be effectively induced to differentiate into DAPs capable of differentiating into functional neurons both in vivo and in vitro. In rat models of PD, the transplanted hiPSCs-DAPs can survive for more than 8 weeks in the MFB and differentiate into multiple functional neurocytes to ameliorate neurological deficits of the rats, suggesting the potential value of hiPSCs-DAPs transplantation for treatment of neurological diseases.

Organoides: fundamentos, presente y futuro / Organoids: fundamentals, present and future

RESUMEN Los organoides son estructuras miniaturizadas, generadas principalmente a partir de células madre pluripotentes inducidas, que se cultivan en el laboratorio conservando sus características innatas o adquiridas. Tienen el potencial de reproducir procesos de desarrollo biológico, modelar procesos patológicos que permitirán el descubrimiento de nuevos fármacos y propicien la medicina regenerativa. Sin embargo, estas experiencias requieren perfeccionamiento constante porque pueden haberse realizado variaciones en la constitución de estos órganos. Por ello, el presente artículo tiene como objetivo revisar la información actualizada sobre organoides y sus procesos experimentales básicos y recientes, empezando por la gastrulación, para tratar de imitar, en lo posible, la formación de las tres capas: ectodermo, mesodermo y endodermo, incluyendo los factores que intervienen en la inducción, diferenciación y maduración en la generación de estos organoides. Asimismo, el diseño y preparación de medios de cultivo altamente especializados que permitan obtener el órgano seleccionado con la mayor precisión y seguridad. Se realizó una búsqueda de artículos originales y de revisión publicados en PubMed, Nature y Science. Los artículos se seleccionaron por sus resúmenes y por su texto completo. Las conclusiones de este articulo destacan las ventajas futuras en el uso y aplicaciones de los organoides.

ABSTRACT Organoids are tiny structures, mainly generated from induced pluripotent stem cells, which are cultured in the laboratory while retaining their innate or acquired characteristics. They have the potential to reproduce biological development processes, model pathological processes that will enable the discovery of new drugs and promote regenerative medicine. However, these processes require constant improvement because variations may have occurred in the constitution of the organs. Therefore, this article aims to review updated information on organoids and their basic and recent experimental processes, starting with gastrulation, in an attempt to mimic, as much as possible, the formation of the three layers: ectoderm, mesoderm and endoderm; as well as the information regarding the factors involved in the induction, differentiation and maturation during the generation of organoids. Likewise, the design and preparation of highly specialized culture media that allow obtaining the selected organ with the highest precision and safety. We searched for original and review articles published in PubMed, Nature and Science. Articles were selected for their abstracts and full text. The conclusions of this article highlight the future advantages in the use and applications of organoids.

Research progress in research on platelets derived from induced pluripotent stem cells in vitro / 国际生物医学工程杂志

Currently, there are insufficient sources of platelets for clinical transfusion, and there are risks of alloimmune reactions and transfusion-transmitted infections (TTI) after transfusion. In recent years, platelets derived from human induced pluripotent stem cells (hiPSCs) have become one of the hottest research topics in the transfusion community, and studies have shown that they have the potential to address the limitations of platelet transfusion and alleviate the conflict between platelet supply and demand in clinical settings. However, the efficiency of hiPSCs in producing functional platelets in vitro is still low, and the yield and quality are still far below clinical transfusion standards. In this review, the basis and applications related to hiPSCs-derived platelets, studies related to human leukocyte antigen (HLA) gene-silenced hiPSC-derived platelets, and challenges faced by hiPSCs-derived platelet products were reviewed, providing references for in-depth research and future clinical applications of hiPSCs-derived platelets.

Hypoxia promotes differentiation of human induced pluripotent stem cells into embryoid bodies in vitro / 南方医科大学学报

OBJECTIVE@#To investigate effects of physiological hypoxic conditions on suspension and adherence of embryoid bodies (EBs) during differentiation of human induced pluripotent stem cells (hiPSCs) and explore the underlying mechanisms.@*METHODS@#EBs in suspension culture were divided into normoxic (21% O2) and hypoxic (5% O2) groups, and those in adherent culture were divided into normoxic, hypoxic and hypoxia + HIF-1α inhibitor (echinomycin) groups. After characterization of the pluripotency with immunofluorescence assay, the hiPSCs were digested and suspended under normoxic and hypoxic conditions for 5 days, and the formation and morphological changes of the EBs were observed microscopically; the expressions of the markers genes of the 3 germ layers in the EBs were detected. The EBs were then inoculated into petri dishes for further culture in normoxic and hypoxic conditions for another 2 days, after which the adhesion and peripheral expansion rate of the adherent EBs were observed; the changes in the expressions of HIF-1α, β-catenin and VEGFA were detected in response to hypoxic culture and echinomycin treatment.@*RESULTS@#The EBs cultured in normoxic and hypoxic conditions were all capable of differentiation into the 3 germ layers. The EBs cultured in hypoxic conditions showed reduced apoptotic debris around them with earlier appearance of cystic EBs and more uniform sizes as compared with those in normoxic culture. Hypoxic culture induced more adherent EBs than normoxic culture (P < 0.05) with also a greater outgrowth rate of the adherent EBs (P < 0.05). The EBs in hypoxic culture showed significantly up-regulated mRNA expressions of β-catenin and VEGFA (P < 0.05) and protein expressions of HIF-1 α, β-catenin and VEGFA (P < 0.05), and their protein expresisons levels were significantly lowered after treatment with echinomycin (P < 0.05).@*CONCLUSION@#Hypoxia can promote the formation and maturation of suspended EBs and enhance their adherence and post-adherent proliferation without affecting their pluripotency for differentiation into all the 3 germ layers. Our results provide preliminary evidence that activation of HIF-1α/β-catenin/VEGFA signaling pathway can enhance the differentiation potential of hiPSCs.

Quantitative proteomics revealed extensive microenvironmental changes after stem cell transplantation in ischemic stroke / 医学前沿

The local microenvironment is essential to stem cell-based therapy for ischemic stroke, and spatiotemporal changes of the microenvironment in the pathological process provide vital clues for understanding the therapeutic mechanisms. However, relevant studies on microenvironmental changes were mainly confined in the acute phase of stroke, and long-term changes remain unclear. This study aimed to investigate the microenvironmental changes in the subacute and chronic phases of ischemic stroke after stem cell transplantation. Herein, induced pluripotent stem cells (iPSCs) and neural stem cells (NSCs) were transplanted into the ischemic brain established by middle cerebral artery occlusion surgery. Positron emission tomography imaging and neurological tests were applied to evaluate the metabolic and neurofunctional alterations of rats transplanted with stem cells. Quantitative proteomics was employed to investigate the protein expression profiles in iPSCs-transplanted brain in the subacute and chronic phases of stroke. Compared with NSCs-transplanted rats, significantly increased glucose metabolism and neurofunctional scores were observed in iPSCs-transplanted rats. Subsequent proteomic data of iPSCs-transplanted rats identified a total of 39 differentially expressed proteins in the subacute and chronic phases, which are involved in various ischemic stroke-related biological processes, including neuronal survival, axonal remodeling, antioxidative stress, and mitochondrial function restoration. Taken together, our study indicated that iPSCs have a positive therapeutic effect in ischemic stroke and emphasized the wide-ranging microenvironmental changes in the subacute and chronic phases.

An improved method to generate megakaryocytes from human induced pluripotent stem cells / 中国输血杂志

【Objective】 To optimize the existing spin-EB method and promote human induced pluripotent stem cells (hiPSCs) differentiate into megakaryocytes (MKs). 【Methods】 In this study, the initial inoculation amount of hiPSCs was increased from 3 500 cells/well to 8 000 cells/well, and the size of EB was increased. By observing the generation time of EB- hematopoietic cells during differentiation, and detecting the proliferation of CD34+ hematopoietic progenitor cells and CD41+ MKs in different stages, it was studied whether the optimized scheme could promote the differentiation of hiPSCs into hematopoietic progenitor cells(HPCs) and MKs. 【Results】 By increasing the initial inoculation amount of hiPSCs and the size of EB, the differentiation of hiPSCs into HPCs and MKs and the cell production efficiency can be promoted. 【Conclusion】 Our research describes an optimized and repeatable differentiation method, which can produce hematopoietic progenitor cells and mature MKs from hiPSCs in a relatively short time with higher yield. It is of great clinical significance and broad scientific research prospect to continuously optimize the culture scheme of hiPSCs differentiation to produce MKs and platelets in vitro, and to promote large-scale platelet generation in vitro in transfusion medicine.

Development of a motor neurons-specific fluorescence reporter system / 生物工程学报

Human induced pluripotent stem cells (hiPSCs) have the potential to differentiate into multiple cell types. Motor neurons (MNs) differentiated from hiPSCs are important models of many motor neuron diseases. To simplify the identification of MNs, lentivirus vectors were used to transfer MNs-specific promoter HB9 and red fluorescent protein (RFP) gene into hiPSCs-derived human neural stem cells (hNSCs). Stable positive cells hNSCs-HB9-RFP-Puro were obtained after antibiotic selection. Subsequently, the positive cell line was infected with lentiviruses LV-Ngn2-Sox11-GFP and LV-Isl1-Lhx3-Hygro, which overexpressed the MNs differentiation transcription factor, and differentiated to MNs directly. Differentiated mature MNs showed neuron-like structure, expressed RFP and neuron-related markers β-tubulin and choline acetyltransferase (ChAT) under the control of the MNs-specific promoter HB9. The fluorescence reporter system provides a visual method for directed differentiation and identification of MNs, and may promote the applications of MNs in disease models and drug screening.

Clinical studies using stem cells for treatment of retinal diseases: state of the art / Estudos clínicos com uso de células-tronco para tratamento de doenças da retina: estado da arte

ABSTRACT Degenerative retinal diseases such as retinitis pigmentosa, Stargardt's macular dystrophy, and age-related macular degeneration are characterized by irreversible loss of vision due to direct or indirect photoreceptor damage. No effective treatments exist, but stem cell studies have shown promising results. Our aim with this review was to describe the types of stem cells that are under study, their effects, and the main clinical trials involving them.

RESUMO As doenças degenerativas da retina, como retinose pigmentar, distrofia macular de Stargardt e degeneração macular relaciona à idade, são caracterizadas por perda irre versível da visão devido a danos diretos ou indiretos aos fotorreceptores. Não existem tratamentos eficazes, porém os estudos com células-tronco mostraram resultados promissores. Nosso objetivo com esta revisão foi descrever os tipos de células-tronco em estudo, seus efeitos e os principais ensaios clínicos que as envolvem.

Smad1/5 signal transduction regulates the ameloblastic differentiation of induced pluripotent stem cells

Abstract Induced pluripotent stem (iPS) cells could be induced into ameloblast-like cells by ameloblasts serum-free conditioned medium (ASF-CM), and bone morphogenetic proteins (BMPs) might be essential during the regulation of this process. The present study investigates the signal transduction that regulates the ameloblastic differentiation of iPS cells induced by ASF-CM. Mouse iPS cells were characterized and then cultured for 14 days in epithelial cell medium (control) or ASF-CM. Bone morphogenetic protein receptor II (BMPR-II) siRNA, inhibitor of Smad1/5 phosphorylation activated by activin receptor-like kinase (ALK) receptors, and inhibitors of mitogen-activated protein kinases (MAPKs) phosphorylation were used to treat the iPS cells in combination with ASF-CM. Real-time PCR, western blotting, and immunofluorescent staining were used to evaluate the expressions of ameloblast markers ameloblastin, enamelin, and cytokeratin-14. BMPR-II gene and protein levels increased markedly in ASF-CM-treated iPS cells compared with the controls, while the mRNA levels of Bmpr-Ia and Bmpr-Ib were similar between the ASF-CM and control groups. ASF-CM stimulation significantly increased the gene and protein expression of ameloblastin, enamelin and cytokeratin-14, and phosphorylated SMAD1/5, p38 MAPK, and ERK1/2 MAPK compared with the controls. Knockdown of BMPR-II and inhibition of Smad1/5 phosphorylation both could significantly reverse the increased expression of ameloblastin, enamelin, and cytokeratin-14 induced by ASF-CM, while neither inhibition of p38 nor ERK1/2 phosphorylation had significant reversing effects. We conclude that smad1/5 signaling transduction, activated by ALK receptors, regulates the ameloblastic differentiation of iPS cells induced by ameloblast-conditioned medium.

Engraftment of human induced pluripotent stem cell-derived myogenic progenitors restores dystrophin in mice with duchenne muscular dystrophy

BACKGROUND: Duchenne muscular dystrophy (DMD) is a devastating genetic muscular disorder with no effective treatment that is caused by the loss of dystrophin. Human induced pluripotent stem cells (hiPSCs) offer a promising unlimited resource for cell-based therapies of muscular dystrophy. However, their clinical applications are hindered by inefficient myogenic differentiation, and moreover, the engraftment of non-transgene hiPSC-derived myogenic progenitors has not been examined in the mdx mouse model of DMD. METHODS: We investigated the muscle regenerative potential of myogenic progenitors derived from hiPSCs in mdx mice. The hiPSCs were transfected with enhanced green fluorescent protein (EGFP) vector and defined as EGFP hiPSCs. Myogenic differentiation was performed on EGFP hiPSCs with supplementary of basic fibroblast growth factor, forskolin, 6-bromoindirubin-3'-oxime as well as horse serum. EGFP hiPSCs-derived myogenic progenitors were engrafted into mdx mice via both intramuscular and intravenous injection. The restoration of dystrophin expression, the ratio of central nuclear myofibers, and the transplanted cells-derived satellite cells were accessed after intramuscular and systemic transplantation. RESULTS: We report that abundant myogenic progenitors can be generated from hiPSCs after treatment with these three small molecules, with consequent terminal differentiation giving rise to mature myotubes in vitro. Upon intramuscular or systemic transplantation into mdx mice, these myogenic progenitors engrafted and contributed to human-derived myofiber regeneration in host muscles, restored dystrophin expression, ameliorated pathological lesions, and seeded the satellite cell compartment in dystrophic muscles. CONCLUSIONS: This study demonstrates the muscle regeneration potential of myogenic progenitors derived from hiPSCs using non-transgenic induction methods. Engraftment of hiPSC-derived myogenic progenitors could be a potential future therapeutic strategy to treat DMD in a clinical setting.

Smad1/5 signal transduction regulates the ameloblastic differentiation of induced pluripotent stem cells

Abstract Induced pluripotent stem (iPS) cells could be induced into ameloblast-like cells by ameloblasts serum-free conditioned medium (ASF-CM), and bone morphogenetic proteins (BMPs) might be essential during the regulation of this process. The present study investigates the signal transduction that regulates the ameloblastic differentiation of iPS cells induced by ASF-CM. Mouse iPS cells were characterized and then cultured for 14 days in epithelial cell medium (control) or ASF-CM. Bone morphogenetic protein receptor II (BMPR-II) siRNA, inhibitor of Smad1/5 phosphorylation activated by activin receptor-like kinase (ALK) receptors, and inhibitors of mitogen-activated protein kinases (MAPKs) phosphorylation were used to treat the iPS cells in combination with ASF-CM. Real-time PCR, western blotting, and immunofluorescent staining were used to evaluate the expressions of ameloblast markers ameloblastin, enamelin, and cytokeratin-14. BMPR-II gene and protein levels increased markedly in ASF-CM-treated iPS cells compared with the controls, while the mRNA levels of Bmpr-Ia and Bmpr-Ib were similar between the ASF-CM and control groups. ASF-CM stimulation significantly increased the gene and protein expression of ameloblastin, enamelin and cytokeratin-14, and phosphorylated SMAD1/5, p38 MAPK, and ERK1/2 MAPK compared with the controls. Knockdown of BMPR-II and inhibition of Smad1/5 phosphorylation both could significantly reverse the increased expression of ameloblastin, enamelin, and cytokeratin-14 induced by ASF-CM, while neither inhibition of p38 nor ERK1/2 phosphorylation had significant reversing effects. We conclude that smad1/5 signaling transduction, activated by ALK receptors, regulates the ameloblastic differentiation of iPS cells induced by ameloblast-conditioned medium.

Role of ERRα in regulating ATP synthesis in hiPSCs-derived cardiomyocytes / 解放军医学杂志

Objective: To investigate the role of estrogen-related receptor alpha (ERRα) in regulating the adenosine triphosphate (ATP) synthesis in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Methods: Undifferentiated human induced pluripotent stem cells (hiPSCs) were induced to differentiate into cardiomyocytes by sequential transient activation/inhibition of Wnt signaling pathway. Immunofluorescence was used to detect the expression of pluripotency markers sex determining region Y-box 2 (SOX2), stage specific embryonic antigen 4 (SSEA4) and tumor resistance antigen 1-60 (TRA-1-60) in hiPSCs and the expression of cardiac specific markers cardiac troponin T (cTnT) and connexin 43 (Cx43) in hiPSCCMs, respectively; RT-qPCR was used to detect the mRNA expression levels of cardiac troponin T2 (TNNT2) and myosin heavy chain 6 (MYH6) in hiPSCs and hiPSCs-CMs; Western blotting was performed to detect the protein expression levels of ERRα, cytochrome C (CytC) and mitochondrial pyruvate carrier 1 (MPC1) in hiPSCs-CMs. Additionally, the ERRα-specific inhibitor XCT790 was used to treat the hiPSC-CMs, and then the protein expressions of ERRα, CytC and MPC1 were detected by Western blotting, and the changes of cell viability, intracellular ATP content and mitochondrial membrane potential were measured by assay kits. Results: Immunofluorescence results showed that hiPSCs expressed SOX2, SSEA4 and TRA-1-60, while hiPSC-CMs expressed cTnT and Cx43; compared with hiPSCs, the mRNA levels of TNNT2 and MYH6 in hiPSC-CMs increased significantly (82.820 ± 2.005 vs. 1.001 ± 0.029, 90982.000 ± 1968.000 vs. 1.003 ± 0.053, respectively, P<0.05), and intracellular ATP content and protein expression levels of ERRα, CytC and MPC1 also increased significantly [(9.905 ± 1.286) nmol/mg protein vs. (4.582 ± 0.141) nmol/mg protein, 5.392 ± 0.313 vs. 1.050 ± 0.076, 8.954 ± 0.293 vs. 1.071 ± 0.067, 2.605 ± 0.088 vs. 1.031 ± 0.091, respectively] with significant differences (P<0.05). Furthermore, compared with the control group, 10 μmol/L XCT790 could effectively inhibit the protein activity of ERRα in hiPSC-CMs without cytotoxicity, and reduced intracellular ATP content and mitochondrial membrane potential [(4.903 ± 1.158) nmol/mg protein vs. (9.310 ± 0.980) nmol/mg protein, 1.407 ± 0.022 vs. 1.977 ± 0.093, respectively], meanwhile down-regulated the protein expression levels of MPC1 and CytC in hiPSC-CMs (0.705 ± 0.019 vs. 0.897 ± 0.011, 0.594 ± 0.021 vs. 0.797 ± 0.025, respectively, P<0.05). Conclusions: The increase of ATP content after differentiation of hiPSCs into cardiomyocytes is related to the increase of ERRα expression. In hiPSC-CMs, ERRα may regulate the ATP synthesis though regulating the mitochondrial membrane potential and the protein expression of CytC and MPC1.

New insight intocell transplantation for repairing intervertebral discs / 中国组织工程研究

BACKGROUND: Current treatment of disc degeneration is limited to palliative care or active surgical intervention, but neither can it slow or reverse disease progression, nor is the long-term efficacy satisfactory. In recent years, with the continuous development of tissue engineering and regenerative medicine, the use of cell therapy to repair degenerative intervertebral discs has attracted more and more researchers’ attention. OBJECTIVE: To summarize the current status of cell transplantation in the treatment of intervertebral disc degeneration, and to provide theoretical basis and experimental basis for future research. METHODS: The relevant articles were retrieved from the CNKI, WanFang and PubMed databases by computer. The search time was set from January 2001 to January 2019. The keywords were “intervertebral disc degeneration, cell therapy, stem cells, cell transplantation” in Chinese and English, respectively. Articles related to stem cell treatment of intervertebral disc degeneration, especially focusing on the latest experimental and clinical research results, were included. RESULTS AND CONCLUSION: Degeneration of the intervertebral disc is mainly caused by the decreased vitality and quantity of nucleus pulposus cells, the reduction of proteoglycan synthesis, the dehydration of nucleus pulposus and the increase of metabolic waste. Continuous explorations on the therapeutic mechanism by which cell transplantation promotes nucleus pulposus regeneration cannot only provide a more detailed understanding of the pathogenesis and repair mechanism of intervertebral disc degeneration, but also give new strategies for the prevention and cell therapy of other related diseases.