Efficient generation of transgene-free human induced pluripotent stem cells (iPSCs) by temperature-sensitive Sendai virus vectors. Proc Natl Acad Sci U S A. 2011;108:14234-14239. [PMID: 21821793 DOI: 10.1073/pnas.1103509108]

Generation of induced pluripotent stem cells from a small amount of human peripheral blood using a combination of activated T cells and Sendai virus

Induced pluripotent stem cells (iPSCs) have become important cell sources for genetic disease models, and they have the potential to be cell sources for future clinical therapies. However, invasive tissue sampling reduces the number of candidates who consent to donate cells for iPSC generation. In addition, integrated transgenes can potentially insert at inappropriate points in the genome, and in turn have a direct oncogenic effect. Technical modifications using a combination of activated T cells and a temperature-sensitive mutant of Sendai virus (SeV) can avoid invasive tissue sampling and residual transgene issues in generating iPSCs. Such advances may increase the number of consenting patients for cell donations. Here we present a detailed protocol for the generation of iPSCs from a small amount of human peripheral blood using a combination of activated T cells and mutant SeV encoding human OCT3/4, SOX2, KLF4 and c-MYC; T cell-derived iPSCs can be generated within 1 month of blood sampling.

Investigating cellular identity and manipulating cell fate using induced pluripotent stem cells

Induced pluripotent stem (iPS) cells, obtained from reprogramming somatic cells by ectopic expression of a defined set of transcription factors or chemicals, are expected to be used as differentiated cells for drug screening or evaluations of drug toxicity and cell replacement therapies. As pluripotent stem cells, iPS cells are similar to embryonic stem (ES) cells in morphology and marker expression. Several types of iPS cells have been generated using combinations of reprogramming molecules and/or small chemical compounds from different types of tissues. A comprehensive approach, such as global gene or microRNA expression analysis and whole genomic DNA methylation profiling, has demonstrated that iPS cells are similar to their embryonic counterparts. Considering the substantial variation among iPS cell lines reported to date, the safety and therapeutic implications of these differences should be thoroughly evaluated before they are used in cell therapies. Here, we review recent research defining the concept of standardization for iPS cells, their ability to differentiate and the identity of the differentiated cells.

Reprogramming of gastrointestinal cancer cells

Cell reprogramming reverts cells to multipotent, preprogrammed states by re-establishing epigenetic markers. It can also induce considerable malignant phenotype modification. Because key events in cancer relapse and metastasis, including epithelial-mesenchymal transition phenotypes, are regulated primarily by reversible and transient epigenetic modifications rather than the accumulation of irreversible and stable genetic abnormalities, studying dynamic mechanisms regulating these biological processes is important. Transcription factors for induced pluripotent stem cells and non-coding microRNAs allow pluripotent phenotype induction. We present the current knowledge of the possible applications of cell reprogramming in reducing aggressive phenotype expression, which can induce tumor cell hibernation and maintain appropriate phenotypes, thereby minimizing relapse and metastasis after surgical resection of gastrointestinal cancer.

Efficient reprogramming of human cord blood CD34+ cells into induced pluripotent stem cells with OCT4 and SOX2 alone

The reprogramming of cord blood (CB) cells into induced pluripotent stem cells (iPSCs) has potential applications in regenerative medicine by converting CB banks into iPSC banks for allogeneic cell replacement therapy. Therefore, further investigation into novel approaches for efficient reprogramming is necessary. Here, we show that the lentiviral expression of OCT4 together with SOX2 (OS) driven by a strong spleen focus-forming virus (SFFV) promoter in a single vector can convert 2% of CB CD34(+) cells into iPSCs without additional reprogramming factors. Reprogramming efficiency was found to be critically dependent upon expression levels of OS. To generate transgene-free iPSCs, we developed an improved episomal vector with a woodchuck post-transcriptional regulatory element (Wpre) that increases transgene expression by 50%. With this vector, we successfully generated transgene-free iPSCs using OS alone. In conclusion, high-level expression of OS alone is sufficient for efficient reprogramming of CB CD34(+) cells into iPSCs. This report is the first to describe the generation of transgene-free iPSCs with the use of OCT4 and SOX2 alone. These findings have important implications for the clinical applications of iPSCs.

Dopamine neurons derived from human ES cells efficiently engraft in animal models of Parkinson's disease

Human pluripotent stem cells (hPSCs) are a promising source of cells for applications in regenerative medicine. Directed differentiation of hPSCs into specialized cells such as spinal motoneurons¹ or midbrain dopamine (DA) neurons² has been achieved. However, the effective use of hPSCs for cell therapy has lagged behind. While mouse PSC-derived DA neurons have shown efficacy in models of Parkinson’s disease (PD)^{3, 4}, DA neurons from human PSCs generally display poor in vivo performance⁵. There are also considerable safety concerns for hPSCs related to their potential for teratoma formation or neural overgrowth^{6, 7}

Here we present a novel floor plate-based strategy for the derivation of human DA neurons that efficiently engraft in vivo, suggesting that past failures were due to incomplete specification rather than a specific vulnerability of the cells. Midbrain floor plate precursors are derived from hPSCs in 11 days following exposure to small molecule activators of sonic hedgehog (SHH) and canonical WNT signaling. Engraftable midbrain DA neurons are obtained by day 25 and can be maintained in vitro for several months. Extensive molecular profiling, biochemical and electrophysiological data define developmental progression and confirm identity of hPSC-derived midbrain DA neurons. In vivo survival and function is demonstrated in PD models using three host species. Long-term engraftment in 6-OHDA-lesioned mice and rats demonstrates robust survival of midbrain DA neurons, complete restoration of amphetamine-induced rotation behavior and improvements in tests of forelimb use and akinesia. Finally, scalability is demonstrated by transplantation into Parkinsonian monkeys. Excellent DA neuron survival, function and lack of neural overgrowth in the three animal models indicate promise for the development of cell based therapies in PD.

Human pluripotent stem cells for disease modelling and drug screening

Considerable hope surrounds the use of disease-specific pluripotent stem cells to generate models of human disease allowing exploration of pathological mechanisms and search for new treatments. Disease-specific human embryonic stem cells were the first to provide a useful source for studying certain disease states. The recent demonstration that human somatic cells, derived from readily accessible tissue such as skin or blood, can be converted to embryonic-like induced pluripotent stem cells (hiPSCs) has opened new perspectives for modelling and understanding a larger number of human pathologies. In this review, we examine the opportunities and challenges for the use of disease-specific pluripotent stem cells in disease modelling and drug screening. Progress in these areas will substantially accelerate effective application of disease-specific human pluripotent stem cells for drug screening.

[Leukocyte count of puerperal sows]

147 blood samples of postparturient sows of a secluded housing were taken. The samples were conserved with ACD-solution. The influence of the number and week of the lactation and the health of the sow, determined by puerperal diseases was studied. Hematological values of healthy postparturient sows are: leucocytes 12.6 +/- 2.2 G/l; basophile granulocytes 0.1 +/- 0.1 G/l, eosinophile granulocytes 0.5 +/- 0.4 G/l; banded neutrophile granulocytes 1.3 +/- 0.6 G/l, segmented neutrophile granulocytes 5.2 +/- 1.4 G/l; lymphocytes 5.5 +/- 1.4 G/l, monocytes 0.3 +/- 0.3 G/l. The leucocyte number is lower in the investigated herd compared with quotations in the literature. This is based on the good health conditions in the herd. Changes due to the number and week of the lactation have no clinical relevance. Health status, here described by puerperal diseases is the significant influencing factor of the leucocyte number. The severity of puerperal diseases is significant. Due to puerperal diseases the leucocyte number rises quickly after a short drop about 2 G/l. The number of the neutrophile granulocytes increases, but the lymphocyte number is reduced at the beginning of the illness. The application of ACD-solution for stabilizing of great amounts of blood samples under practical conditions is demonstrated. It is possible to stabilize pigs blood well.