参考文献

Reprogramming of patient cells to human induced pluripotent stem cells (hiPSC) has facilitated in vitro disease modeling studies aiming at deciphering the molecular and cellular mechanisms that contribute to disease pathogenesis and progression. To fully exploit the potential of hiPSC for biomedical applications,technologies that enable the standardized generation and expansion of hiPSC from large numbers of donors are required. Paralleled automated processes for the expansion of hiPSC could provide an opportunity to maximize the generation of hiPSC collections from patient cohorts while minimizing hands-on time and costs. In order to develop a simple method for the parallel expansion of human pluripotent stem cells (hPSC) we established a protocol for their cultivation as undifferentiated aggregates in a bench-top bioreactor system (BioLevitator™). We show that long-term expansion (10 passages) of hPSCs either in mTeSR or E8 medium preserved a normal karyotype,three-germ-layer differentiation potential and high expression of pluripotency-associated markers. The system enables the expansion from low inoculation densities (0.3 × 10(5) cells/mL) and provides a simplified,cost-efficient and time-saving method for the provision of hiPSC at midi-scale. Implementation of this protocol in cell production schemes has the potential to advance cell manufacturing in many areas of hiPSC-based medical research. View Publication

Transcription factor-mediated reprograming is a powerful method to study cell fate changes. In this study,we demonstrate that the transcription factor Gata6 can initiate reprograming of multiple cell types to induced extraembryonic endoderm stem (iXEN) cells. Intriguingly,Gata6 is sufficient to drive iXEN cells from mouse pluripotent cells and differentiated neural cells. Furthermore,GATA6 induction in human embryonic stem (hES) cells also down-regulates pluripotency gene expression and up-regulates extraembryonic endoderm (ExEn) genes,revealing a conserved function in mediating this cell fate switch. Profiling transcriptional changes following Gata6 induction in mES cells reveals step-wise pluripotency factor disengagement,with initial repression of Nanog and Esrrb,then Sox2,and finally Oct4,alongside step-wise activation of ExEn genes. Chromatin immunoprecipitation and subsequent high-throughput sequencing analysis shows Gata6 enrichment near pluripotency and endoderm genes,suggesting that Gata6 functions as both a direct repressor and activator. Together,this demonstrates that Gata6 is a versatile and potent reprograming factor that can act alone to drive a cell fate switch from diverse cell types. View Publication

PURPOSE We conducted an open-label,single-arm Phase I/II clinical trial in metastatic CRPC (mCRPC) patients eligible for docetaxel combined with treatment with autologous mature dendritic cells (DCs) pulsed with killed LNCaP prostate cancer cells (DCVAC/PCa). The primary and secondary endpoints were safety and immune responses,respectively. Overall survival (OS),followed as a part of the safety evaluation,was compared to the predicted OS according to the Halabi and MSKCC nomograms. EXPERIMENTAL DESIGN Twenty-five patients with progressive mCRPC were enrolled. Treatment comprised of initial 7 days administration of metronomic cyclophosphamide 50 mg p.o. DCVAC/PCa treatment consisted of a median twelve doses of 1 × 107 dendritic cells per dose injected s.c. (Aldara creme was applied at the site of injection) during a one-year period. The initial 2 doses of DCVAC/PCa were administered at a 2-week interval,followed by the administration of docetaxel (75 mg/m2) and prednisone (5 mg twice daily) given every 3 weeks until toxicity or intolerance was observed. The DCVAC/PCa was then injected every 6 weeks up to the maximum number of doses manufactured from one leukapheresis. RESULTS No serious DCVAC/PCa-related adverse events have been reported. The median OS was 19 months,whereas the predicted median OS was 11.8 months with the Halabi nomogram and 13 months with the MSKCC nomogram. Kaplan-Meier analyses showed that patients had a lower risk of death compared with both MSKCC (Hazard Ratio 0.26,95% CI: 0.13-0.51) and Halabi (Hazard Ratio 0.33,95% CI: 0.17-0.63) predictions. We observed a significant decrease in Tregs in the peripheral blood. The long-term administration of DCVAC/PCa led to the induction and maintenance of PSA specific T cells. We did not identify any immunological parameter that significantly correlated with better OS. CONCLUSIONS In patients with mCRPC,the combined chemoimmunotherapy with DCVAC/PCa and docetaxel was safe and resulted in longer than expected survival. Concomitant chemotherapy did not preclude the induction of specific anti-tumor cytotoxic T cells. View Publication

Despite major advances in the pathophysiological understanding of peripheral nerve damage,the treatment of nerve injuries still remains an unmet medical need. Nerve guidance conduits present a promising treatment option by providing a growth-permissive environment that 1) promotes neuronal cell survival and axon growth and 2) directs axonal extension. To this end,we designed an electrospun nerve guidance conduit using a blend of polyurea and poly-caprolactone with both biochemical and topographical cues. Biochemical cues were integrated into the conduit by functionalizing the polyurea with RGD to improve cell attachment. Topographical cues that resemble natural nerve tissue were incorporated by introducing intraluminal microchannels aligned with nanofibers. We determined that electrospinning the polymer solution across a two electrode system with dissolvable sucrose fibers produced a polymer conduit with the appropriate biomimetic properties. Human neural stem cells were cultured on the conduit to evaluate its ability to promote neuronal growth and axonal extension. The nerve guidance conduit was shown to enhance cell survival,migration,and guide neurite extension. View Publication

Monomeric clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated 9 (Cas9) nucleases have been widely adopted for simple and robust targeted genome editing but also have the potential to induce high-frequency off-target mutations. In principle,two orthogonal strategies for reducing off-target cleavage,truncated guide RNAs (tru-gRNAs) and dimerization-dependent RNA-guided FokI-dCas9 nucleases (RFNs),could be combined as tru-RFNs to further improve genome editing specificity. Here we identify a robust tru-RFN architecture that shows high activity in human cancer cell lines and embryonic stem cells. Additionally,we demonstrate that tru-gRNAs reduce the undesirable mutagenic effects of monomeric FokI-dCas9. Tru-RFNs combine the advantages of two orthogonal strategies for improving the specificity of CRISPR-Cas nucleases and therefore provide a highly specific platform for performing genome editing. View Publication

Inhibition of metabolic features which distinguish cancer cells from their non-malignant counterparts is a promising approach to cancer treatment. Energy support for drug extrusion in multidrug resistance (MDR) is a potential target for metabolic inhibition. Two major sources of ATP-based metabolic energy are partial (glycolysis) and complete (mitochondrial oxidative phosphorylation) oxidation of metabolic fuels. In cancer cells,the balance between them tends to be shifted toward glycolysis; this shift is considered to be characteristic of the cancer metabolic phenotype. Numerous earlier studies,conducted with cells cultured in a monolayer (2-D model),suggested inhibition of glycolytic ATP production as an efficient tool to suppress MDR in cancer cells. Yet,more recent work challenged the appropriateness of the 2-D model for such studies and suggested that a more clinically relevant approach would utilize a more advanced cellular model such as a 3-D model. Here,we show that the transition from the 2-D model (cultured monolayer) to a 3-D model (cultured spheroids) introduces essential changes into the concept of energetic suppression of MDR. The 3-D cell organization leads to the formation of a discrete cell subpopulation (not formed in the 2-D model) with elevated MDR transport capacity. This subpopulation has a specific metabolic phenotype (mixed glycolytic/oxidative MDR support) different from that of cells cultured in the 2-D model. Finally,the shift to the oxidative phenotype becomes greater when the spheroids are grown under conditions of lactic acidosis that are typical for solid tumors. The potential clinical significance of these findings is discussed. View Publication

Human embryonic stem cells (hESC) and induced pluripotent stem cells (hiPSC) assert a great future for the cardiovascular diseases,both to study them and to explore therapies. However,a comprehensive assessment of the viral vectors used to modify these cells is lacking. In this study,we aimed to compare the transduction efficiency of recombinant adeno-associated vectors (AAV),adenoviruses and lentiviral vectors in hESC,hiPSC,and the derived cardiomyocytes. In undifferentiated cells,adenoviral and lentiviral vectors were superior,whereas in differentiated cells AAV surpassed at least lentiviral vectors. We also tested four AAV serotypes,1,2,6,and 9,of which 2 and 6 were superior in their transduction efficiency. Interestingly,we observed that AAVs severely diminished the viability of undifferentiated cells,an effect mediated by induction of cell cycle arrest genes and apoptosis. Furthermore,we show that the transduction efficiency of the different viral vectors correlates with the abundance of their respective receptors. Finally,adenoviral delivery of the calcium-transporting ATPase SERCA2a to hESC and hiPSC-derived cardiomyocytes successfully resulted in faster calcium reuptake. In conclusion,adenoviral vectors prove to be efficient for both differentiated and undifferentiated lines,whereas lentiviral vectors are more applicable to undifferentiated cells and AAVs to differentiated cells. View Publication

Adoptive cell therapy is an emerging treatment strategy for a number of serious diseases. Regulatory T (Treg) cells represent 1 cell type of particular interest for therapy of inflammatory conditions,as they are responsible for controlling unwanted immune responses. Initial clinical trials of adoptive transfer of Treg cells in patients with graft-versus-host disease were shown to be safe. However,obtaining sufficient numbers of highly pure and functional Treg cells with minimal contamination remains a challenge. We developed a novel approach to isolate untouched" human Treg cells from healthy donors on the basis of negative selection using the surface markers CD49d and CD127. This procedure� View Publication

Human pluripotent stem cells (hPSCs),such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs),provide a powerful model system for studies of cellular identity and early mammalian development,which hold great promise for regenerative medicine. It is necessary to develop a convenient method to discriminate hPSCs from other cells in clinics and basic research. Herein,a simple and reliable biosensor for stem cell detection was established. In this biosensor system,stage-specific embryonic antigen-3 (SSEA-3) and stage-specific embryonic antigen-4 (SSEA-4) were used to mark human pluripotent stem cells (hPSCs). Antibody specific for SSEA-3 was coated onto magnetic beads for hPSCs enrichment,and antibody specific for SSEA-4 was conjugated with carboxyl-modified tDNA sequence which was used as template for strand displacement amplification (SDA). The amplified single strand DNA (ssDNA) was detected with a lateral flow biosensor (LFB). This biosensor is capable of detecting a minimum of 19 human embryonic stem cells by a strip reader and 100 human embryonic stem cells by the naked eye within 80min. This approach has also shown excellent specificity to distinguish hPSCs from other types of cells,showing that it is promising for specific and handy detection of human pluripotent stem cells. View Publication

Human Embryonic Stem Cells (hESC) offer an important resource as a limitless supply of any differentiated cell type of the human body. Keratocytes,cells from the corneal stroma,may have the potential for restoration of vision in cell therapy and biomedical engineering applications,but these specialized cells are not readily expanded in vitro. Here we describe a two-part method to produce keratocytes from the H1 hESC cell line. The hESC cells,maintained and expanded in feeder-free culture medium are first differentiated to neural crest cells using the stromal-derived inducing activity (SDIA) of the PA6 mouse embryonic fibroblast cell line. The resulting neural crest cells are selected by their expression of cell-surface CD271 and subsequently cultured as 3D pellets in a defined differentiation medium to induce a keratocyte phenotype. View Publication