参考文献

The enthusiasm surrounding the clinical potential of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) is tempered by the fact that key issues regarding their safety,efficacy,and long-term benefits have thus far been suboptimal. Small molecules can potentially relieve these problems at major junctions of stem cell biology and regenerative therapy. In this review we will introduce recent advances in these important areas and the first generation of small molecules used in the regenerative context. Current chemical biology studies will provide the archetype for future interdisciplinary collaborations and improve clinical benefits of cell-based therapies. View Publication

Genetic Parkinson disease (PD) has been associated with mutations in PINK1,a gene encoding a mitochondrial kinase implicated in the regulation of mitochondrial degradation. While the studies so far examined PINK1 function in non-neuronal systems or through PINK1 knockdown approaches,there is an imperative to examine the role of endogenous PINK1 in appropriate human-derived and biologically relevant cell models. Here we report the generation of induced pluripotent stem (iPS) cells from skin fibroblasts taken from three PD patients with nonsense (c.1366CtextgreaterT; p.Q456X) or missense (c.509TtextgreaterG; p.V170G) mutations in the PINK1 gene. These cells were differentiated into dopaminergic neurons that upon mitochondrial depolarization showed impaired recruitment of lentivirally expressed Parkin to mitochondria,increased mitochondrial copy number,and upregulation of PGC-1α,an important regulator of mitochondrial biogenesis. Importantly,these alterations were corrected by lentiviral expression of wild-type PINK1 in mutant iPS cell-derived PINK1 neurons. In conclusion,our studies suggest that fibroblasts from genetic PD can be reprogrammed and differentiated into neurons. These neurons exhibit distinct phenotypes that should be amenable to further mechanistic studies in this relevant biological context. View Publication

The lipocalin mouse 24p3 has been implicated in diverse physiological processes,including apoptosis,iron trafficking,development and innate immunity. Studies from our laboratory as well as others demonstrated the proapoptotic activity of 24p3 in a variety of cultured models. However,a general role for the lipocalin 24p3 in the hematopoietic system has not been tested in vivo. To study the role of 24p3,we derived 24p3 null mice and back-crossed them onto C57BL/6 and 129/SVE backgrounds. Homozygous 24p3(-/-) mice developed a progressive accumulation of lymphoid,myeloid,and erythroid cells,which was not due to enhanced hematopoiesis because competitive repopulation and recovery from myelosuppression were the same as for wild type. Instead,apoptotic defects were unique to many mature hematopoietic cell types,including neutrophils,cytokine-dependent mast cells,thymocytes,and erythroid cells. Thymocytes isolated from 24p3 null mice also displayed resistance to apoptosis-induced by dexamethasone. Bim response to various apoptotic stimuli was attenuated in 24p3(-/-) cells,thus explaining their resistance to the ensuing cell death. The results of these studies,in conjunction with those of previous studies,reveal 24p3 as a regulator of the hematopoietic compartment with important roles in normal physiology and disease progression. Interestingly,these functions are limited to relatively mature blood cell compartments. View Publication

Use of animal feeder layers and serum containing media in the derivation and propagation of induced pluripotent stem cells (iPSCs) can hinder clinical translation,because of the presence of xeno-material/pathogens. A defined and standardized system would be ideal for generating a homogenous population of iPSCs,which closely resembles human embryonic stem cells (hESCs). This article presents a novel and extensive comparison between in-house produced iPSCs and hESCs under feeder" and "feeder-free" conditions� View Publication

Mast cells (MCs) play an important role in the regulation of protective adaptive immune responses against pathogens. However,it is still unclear whether MCs promote such host defense responses via direct effects on T cells or rather by modifying the functions of antigen-presenting cells. To identify the underlying mechanisms of the immunoregulatory capacity of MCs,we investigated the impact of MCs on dendritic cell (DC) maturation and function. We found that murine peritoneal MCs underwent direct crosstalk with immature DCs that induced DC maturation as evidenced by enhanced expression of costimulatory molecules. Furthermore,the MC/DC interaction resulted in the release of the T-cell modulating cytokines IFN-γ,IL-2,IL-6 and TGF-β into coculture supernatants and increased the IL-12p70,IFN-γ,IL-6 and TGF-β secretion of LPS-matured DCs. Such MC-primed" DCs subsequently induced efficient CD4+ T-cell proliferation. Surprisingly� View Publication

PURPOSE: Preclinical in vivo studies can help guide the selection of agents and regimens for clinical testing. However,one of the challenges in screening anticancer therapies is the assessment of off-target human toxicity. There is a need for in vivo models that can simulate efficacy and toxicities of promising therapeutic regimens. For example,hematopoietic cells of human origin are particularly sensitive to a variety of chemotherapeutic regimens,but in vivo models to assess potential toxicities have not been developed. In this study,a xenograft model containing humanized bone marrow is utilized as an in vivo assay to monitor hematotoxicity. EXPERIMENTAL DESIGN: A proof-of-concept,temozolomide-based regimen was developed that inhibits tumor xenograft growth. This regimen was selected for testing because it has been previously shown to cause myelosuppression in mice and humans. The dose-intensive regimen was administered to NOD.Cg-Prkdc(scid)IL2rg(tm1Wjl)/Sz (NOD/SCID/γchain(null)),reconstituted with human hematopoietic cells,and the impact of treatment on human hematopoiesis was evaluated. RESULTS: The dose-intensive regimen resulted in significant decreases in growth of human glioblastoma xenografts. When this regimen was administered to mice containing humanized bone marrow,flow cytometric analyses indicated that the human bone marrow cells were significantly more sensitive to treatment than the murine bone marrow cells and that the regimen was highly toxic to human-derived hematopoietic cells of all lineages (progenitor,lymphoid,and myeloid). CONCLUSIONS: The humanized bone marrow xenograft model described has the potential to be used as a platform for monitoring the impact of anticancer therapies on human hematopoiesis and could lead to subsequent refinement of therapies prior to clinical evaluation. View Publication

A population of CD133(+)Lin(-)CD45(-) very small embryonic/epiblast-like stem cells (VSELs) has been purified by multiparameter sorting from umbilical cord blood (UCB). To speed up isolation of these cells,we employed anti-CD133-conjugated paramagnetic beads followed by staining with Aldefluor to detect aldehyde dehydrogenase (ALDH) activity; we subsequently sorted CD45(-)/GlyA(-)/CD133(+)/ALDH(high) and CD45(-)/GlyA(-)/CD133(+)/ALDH(low) cells,which are enriched for VSELs,and CD45(+)/GlyA /CD133(+)/ALDH(high) and CD45(+)/GlyA(-)/CD133(+)/ALDH(low) cells,which are enriched for hematopoietic stem/progenitor cells (HSPCs). Although freshly isolated CD45(-) VSELs did not grow hematopoietic colonies,the same cells,when activated/expanded over OP9 stromal support,acquired hematopoietic potential and grew colonies composed of CD45(+) hematopoietic cells in methylcellulose cultures. We also observed that CD45(-)/GlyA(-)/CD133(+)/ALDH(high) VSELs grew colonies earlier than CD45(-)/GlyA(-)/CD133(+)/ALDH(low) VSELs,which suggests that the latter cells need more time to acquire hematopoietic commitment. In support of this possibility,real-time polymerase chain reaction analysis confirmed that,whereas freshly isolated CD45(-)/GlyA(-)/CD133(+)/ALDH(high) VSELs express more hematopoietic transcripts (for example,c-myb),CD45(-)/GlyA(-)/CD133(+)/ALDH(low) VSELs exhibit higher levels of pluripotent stem cell markers (for example,Oct-4). More importantly,hematopoietic cells derived from VSELs that were co-cultured over OP9 support were able to establish human lympho-hematopoietic chimerism in lethally irradiated non-obese diabetic/severe combined immunodeficiency mice 4-6 weeks after transplantation. Overall,our data suggest that UCB-VSELs correspond to the most primitive population of HSPCs in UCB. View Publication

The term laminopathies defines a group of genetic disorders caused by defects in the nuclear envelope,mostly the lamins. Lamins are the main constituents of the nuclear lamina,a filamentous meshwork associated with the inner nuclear membrane that provides mechanical stability and plays important roles in processes such as transcription,DNA replication and chromatin organization. More than 300 mutations inlamin A/C have been associated with diverse clinical phenotypes,understanding the molecular basis of these diseases may provide a rationale for treating them. Here we describe the generation of induced pluripotent stem cells (iPSCs) from a patient with inherited dilated cardiomiopathy and 2 patients with distinct accelerated forms of aging,atypical Werner syndrome and Hutchinson Gilford progeria,all of which are caused by mutations in lamin A/C. These cell lines were pluripotent and displayed normal nuclear membrane morphology compared to donor fibroblasts. Their differentiated progeny reproduced the disease phenotype,reinforcing the idea that they represent excellent tools for understanding the role of lamin A/C in normal physiology and the clinical diversity associated with these diseases. View Publication

Age-related macular degeneration (AMD) is one of the major causes of blindness in aging population that progresses with death of retinal pigment epithelium (RPE) and photoreceptor degeneration inducing impairment of central vision. Discovery of human induced pluripotent stem (hiPS) cells has opened new avenues for the treatment of degenerative diseases using patient-specific stem cells to generate tissues and cells for autologous cell-based therapy. Recently,RPE cells were generated from hiPS cells. However,there is no evidence that those hiPS-derived RPE possess specific RPE functions that fully distinguish them from other types of cells. Here,we show for the first time that RPE generated from hiPS cells under defined conditions exhibit ion transport,membrane potential,polarized vascular endothelial growth factor secretion,and gene expression profile similar to those of native RPE. The hiPS-RPE could therefore be a very good candidate for RPE replacement therapy in AMD. However,these cells show rapid telomere shortening,DNA chromosomal damage,and increased p21 expression that cause cell growth arrest. This rapid senescence might affect the survival of the transplanted cells in vivo and therefore,only the very early passages should be used for regeneration therapies. Future research needs to focus on the generation of safe" as well as viable hiPS-derived somatic cells." View Publication

We re-examine the individual components for human embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) culture and formulate a cell culture system in which all protein reagents for liquid media,attachment surfaces and splitting are chemically defined. A major improvement is the lack of a serum albumin component,as variations in either animal- or human-sourced albumin batches have previously plagued human ESC and iPSC culture with inconsistencies. Using this new medium (E8) and vitronectin-coated surfaces,we demonstrate improved derivation efficiencies of vector-free human iPSCs with an episomal approach. This simplified E8 medium should facilitate both the research use and clinical applications of human ESCs and iPSCs and their derivatives,and should be applicable to other reprogramming methods. View Publication