技术资料

Data suggest that clinical applications of human induced pluripotent stem cells (hiPSCs) will be realized. Nonetheless,clinical applications will require hiPSCs that are free of exogenous DNA and that can be manufactured through Good Manufacturing Practice (GMP). Optimally,derivation of hiPSCs should be rapid and efficient in order to minimize manipulations,reduce potential for accumulation of mutations and minimize financial costs. Previous studies reported the use of modified synthetic mRNAs to reprogram fibroblasts to a pluripotent state. Here,we provide an optimized,fully chemically defined and feeder-free protocol for the derivation of hiPSCs using synthetic mRNAs. The protocol results in derivation of fully reprogrammed hiPSC lines from adult dermal fibroblasts in less than two weeks. The hiPSC lines were successfully tested for their identity,purity,stability and safety at a GMP facility and cryopreserved. To our knowledge,as a proof of principle,these are the first integration-free iPSCs lines that were reproducibly generated through synthetic mRNA reprogramming that could be putatively used for clinical purposes. View Publication

The CRISPR/Cas9 system is a rapid and customizable tool for gene editing in mammalian cells. In particular,this approach has widely opened new opportunities for genetic studies in neurological disease. Human neurons can be differentiated in vitro from hPSC (human Pluripotent Stem Cells),hNPCs (human Neural Precursor Cells) or even directly reprogrammed from fibroblasts. Here,we described a new platform which enables,rapid and efficient CRISPR/Cas9-mediated genome targeting simultaneously with three different paradigms for in vitro generation of neurons. This system was employed to inactivate two genes associated with neurological disorder (TSC2 and KCNQ2) and achieved up to 85% efficiency of gene targeting in the differentiated cells. In particular,we devised a protocol that,combining the expression of the CRISPR components with neurogenic factors,generated functional human neurons highly enriched for the desired genome modification in only 5 weeks. This new approach is easy,fast and that does not require the generation of stable isogenic clones,practice that is time consuming and for some genes not feasible. View Publication

A fast track Hot Start" process was implemented to launch the European Bank for Induced Pluripotent Stem Cells (EBiSC) to provide early release of a range of established control and disease linked human induced pluripotent stem cell (hiPSC) lines. Established practice amongst consortium members was surveyed to arrive at harmonised and publically accessible Standard Operations Procedures (SOPs) for tissue procurement View Publication

Specifically ablating genes in human induced pluripotent stem cells (iPSCs) allows for studies of gene function as well as disease mechanisms in disorders caused by loss-of-function (LOF) mutations. While techniques exist for engineering such lines,we have developed and rigorously validated a method of simultaneous iPSC reprogramming while generating CRISPR/Cas9-dependent insertions/deletions (indels). This approach allows for the efficient and rapid formation of genetic LOF human disease cell models with isogenic controls. The rate of mutagenized lines was strikingly consistent across experiments targeting four different human epileptic encephalopathy genes and a metabolic enzyme-encoding gene,and was more efficient and consistent than using CRISPR gene editing of established iPSC lines. The ability of our streamlined method to reproducibly generate heterozygous and homozygous LOF iPSC lines with passage-matched isogenic controls in a single step provides for the rapid development of LOF disease models with ideal control lines,even in the absence of patient tissue. View Publication

Stem cell-based neuronal differentiation has provided a unique opportunity for disease modeling and regenerative medicine. Neurospheres are the most commonly used neuroprogenitors for neuronal differentiation,but they often clump in culture,which has always represented a challenge for neurodifferentiation. In this study,we report a novel method and defined culture conditions for generating sub-type or region-specific neurons from human embryonic and induced pluripotent stem cells derived neurosphere without any genetic manipulation. Round and bright-edged neurospheres were generated in a supplemented knockout serum replacement medium (SKSRM) with 10% CO2,which doubled the expression of the NESTIN,PAX6 and FOXG1 genes compared with those cultured with 5% CO2. Furthermore,an additional step (AdSTEP) was introduced to fragment the neurospheres and facilitate the formation of a neuroepithelial-type monolayer that we termed the neurosphederm". The large neural tube-type rosette (NTTR) structure formed from the neurosphederm� View Publication

We evaluated the feasibility and efficacy of a reduced-intensity conditioning (RIC) regimen of fludarabine and melphalan to achieve rapid complete donor chimerism after allogeneic stem cell transplantation (SCT) in patients with metastatic solid tumors. Between January 1999 and January 2003,8 patients with metastatic breast cancer (BC) and 15 with metastatic renal cell carcinoma (RCC) underwent allogeneic SCT after an RIC regimen of 5 days of fludarabine and 2 days of melphalan. Filgrastim-mobilized stem cells from HLA-identical related or unrelated donors were infused. Prophylaxis for graft-versus-host disease (GVHD) consisted of tacrolimus and methotrexate. All 22 evaluable patients had 100% donor chimerism at day 30 and at all measurement times thereafter. One patient died 19 days after SCT. Nine patients (39%) had grades II to IV acute GVHD and 10 patients (43%) had chronic GVHD. Five patients (22%) died of nonrelapse treatment-related complications. Treatment-related disease response was seen in 10 patients (45%),with 3 complete responses,2 partial responses,and 5 minor responses. Fludarabine-melphalan is a feasible and effective RIC regimen for allogeneic SCT in metastatic BC and RCC. It induces rapid complete donor chimerism without the need for donor lymphocyte infusion. Tumor regression associated with GVHD is consistent with graft-versus-tumor effect. View Publication

Conventionally,researchers remove spontaneously differentiated areas in human pluripotent stem cell (hPSC) colonies by using a finely drawn glass pipette or a commercially available syringe needle. However,when extreme differentiation occurs,it is inefficient to purify the remaining undifferentiated cells,as these undifferentiated areas are too small to be isolated completely with the mechanical method. Antibodies can be utilized to purify the rare undifferentiated cells; however,this type of purification cannot be used in xeno-free culture systems. To avoid the loss of valuable hPSCs,we developed a novel method to isolate undifferentiated hPSCs from extremely differentiated colonies that could be easily adapted to xeno-free culture conditions. This protocol involves dissecting away differentiated areas,dissociating the remaining colony into clumps,seeding small clumps into new dishes,and picking undifferentiated colonies for expansion. Using this method,we routinely achieve completely undifferentiated colonies in one passage without the use of antibody-based purification. View Publication

Advances in cellular reprogramming and stem cell differentiation now enable ex vivo studies of human neuronal differentiation. However,it remains challenging to elucidate the underlying regulatory programs because differentiation protocols are laborious and often result in low neuron yields. Here,we overexpressed two Neurogenin transcription factors in human-induced pluripotent stem cells and obtained neurons with bipolar morphology in 4 days,at greater than 90% purity. The high purity enabled mRNA and microRNA expression profiling during neurogenesis,thus revealing the genetic programs involved in the rapid transition from stem cell to neuron. The resulting cells exhibited transcriptional,morphological and functional signatures of differentiated neurons,with greatest transcriptional similarity to prenatal human brain samples. Our analysis revealed a network of key transcription factors and microRNAs that promoted loss of pluripotency and rapid neurogenesis via progenitor states. Perturbations of key transcription factors affected homogeneity and phenotypic properties of the resulting neurons,suggesting that a systems-level view of the molecular biology of differentiation may guide subsequent manipulation of human stem cells to rapidly obtain diverse neuronal types. View Publication

Available methods for differentiating human embryonic stem cells (ESCs) and induced pluripotent cells (iPSCs) into neurons are often cumbersome,slow,and variable. Alternatively,human fibroblasts can be directly converted into induced neuronal (iN) cells. However,with present techniques conversion is inefficient,synapse formation is limited,and only small amounts of neurons can be generated. Here,we show that human ESCs and iPSCs can be converted into functional iN cells with nearly 100% yield and purity in less than 2weeks by forced expression of a single transcription factor. The resulting ES-iN or iPS-iN cells exhibit quantitatively reproducible properties independent of the cell line of origin,form mature pre- and postsynaptic specializations,and integrate into existing synaptic networks when transplanted into mouse brain. As illustrated by selected examples,our approach enables large-scale studies of human neurons for questions such as analyses of human diseases,examination of human-specific genes,and drug screening View Publication

Casitas B-cell lymphoma (Cbl)-family E3 ubiquitin ligases are negative regulators of tyrosine kinase signaling. Recent work has revealed a critical role of Cbl in the maintenance of hematopoietic stem cell (HSC) homeostasis,and mutations in CBL have been identified in myeloid malignancies. Here we show that,in contrast to Cbl or Cbl-b single-deficient mice,concurrent loss of Cbl and Cbl-b in the HSC compartment leads to an early-onset lethal myeloproliferative disease in mice. Cbl,Cbl-b double-deficient bone marrow cells are hypersensitive to cytokines,and show altered biochemical response to thrombopoietin. Thus,Cbl and Cbl-b play redundant but essential roles in HSC regulation,whose breakdown leads to hematological abnormalities that phenocopy crucial aspects of mutant Cbl-driven human myeloid malignancies. View Publication

RARA (retinoic acid receptor alpha) haploinsufficiency is an invariable consequence of t(15;17)(q22;q21) translocations in acute promyelocytic leukemia (APL). Retinoids and RARA activity have been implicated in hematopoietic self-renewal and neutrophil maturation. We and others therefore predicted that RARA haploinsufficiency would contribute to APL pathogenesis. To test this hypothesis,we crossed Rara(+/-) mice with mice expressing PML (promyelocytic leukemia)-RARA from the cathepsin G locus (mCG-PR). We found that Rara haploinsufficiency cooperated with PML-RARA,but only modestly influenced the preleukemic and leukemic phenotype. Bone marrow from mCG-PR(+/-) × Rara(+/-) mice had decreased numbers of mature myeloid cells,increased ex vivo myeloid cell proliferation,and increased competitive advantage after transplantation. Rara haploinsufficiency did not alter mCG-PR-dependent leukemic latency or penetrance,but did influence the distribution of leukemic cells; leukemia in mCG-PR(+/-) × Rara(+/-) mice presented more commonly with low to normal white blood cell counts and with myeloid infiltration of lymph nodes. APL cells from these mice were responsive to all-trans retinoic acid and had virtually no differences in expression profiling compared with tumors arising in mCG-PR(+/-) × Rara(+/+) mice. These data show that Rara haploinsufficiency (like Pml haploinsufficiency and RARA-PML) can cooperate with PML-RARA to influence the pathogenesis of APL in mice,but that PML-RARA is the t(15;17) disease-initiating mutation. View Publication

Patient-specific human induced pluripotent stem (hiPS) cells not only provide a promising tool for cellular disease models in general,but also open up the opportunity to establish cell-type-specific systems for personalized medicine. One of the crucial prerequisites for these strategies,however,is a fast and efficient reprogramming strategy from easy accessible somatic cell populations. Keratinocytes from plucked human hair had been introduced as a superior cell source for reprogramming purposes compared with the widely used skin fibroblasts. The starting cell population is,however,limited and thereby further optimization in terms of time,efficiency,and quality is inevitable. Here we show that rat embryonic fibroblasts (REFs) should replace mouse embryonic fibroblasts as feeder cells in the reprogramming process. REFs enable a significantly more efficient reprogramming procedure as shown by colony number and total amount of SSEA4-positive cells. We successfully produced keratinocyte-derived hiPS (k-hiPS) cells from various donors. The arising k-hiPS cells display the hallmarks of pluripotency such as expression of stem cell markers and differentiation into all 3 germ layers. The increased reprogramming efficiency using REFs as a feeder layer occurred independent of the proliferation rate in the parental keratinocytes and acts,at least in part,in a non-cell autonomous way by secreting factors known to facilitate pluripotency such as Tgfb1,Inhba and Grem1. Hence,we provide an easy to use and highly efficient reprogramming system that could be very useful for a broad application to generate human iPS cells. View Publication