Clinically compatible advances in blood-derived endothelial progenitor cell isolation and reprogramming for translational applications.

The promise of using induced pluripotent stem cells (iPSCs) for cellular therapies has been hampered by the lack of easily isolatable and well characterized source cells whose genomes have undergone minimal changes during their processing. Blood-derived late-outgrowth endothelial progenitor cells (EPCs) are used for disease modeling and have potential therapeutic uses including cell transplantation and the translation of induced pluripotent stem cell (iPSC) derivatives. However, the current isolation of EPCs has been inconsistent and requires at least 40-80 mL of blood, limiting their wider use. In addition, previous EPC reprogramming methods precluded the translation of EPC-derived iPSCs to the clinic. Here a series of clinically-compatible advances in the isolation and reprogramming of EPCs is presented, including a reduction of blood sampling volumes to 10 mL and use of highly efficient RNA-based reprogramming methods together with autologous human serum, resulting in clinically relevant iPSCs carrying minimal copy number variations (CNVs) compared to their parent line.

Efficient Reprogramming of Human Fibroblasts and Blood-Derived Endothelial Progenitor Cells Using Nonmodified RNA for Reprogramming and Immune Evasion.

mRNA reprogramming results in the generation of genetically stable induced pluripotent stem (iPS) cells while avoiding the risks of genomic integration. Previously published mRNA reprogramming protocols have proven to be inconsistent and time-consuming and mainly restricted to fibroblasts, thereby demonstrating the need for a simple but reproducible protocol applicable to various cell types. So far there have been no published reports using mRNA to reprogram any cell type derived from human blood. Nonmodified synthetic mRNAs are immunogenic and activate cellular defense mechanisms, which can lead to cell death and inhibit mRNA translation upon repetitive transfection. Hence, to overcome RNA-related toxicity we combined nonmodified reprogramming mRNAs (OCT4, SOX2, KLF4, cMYC, NANOG, and LIN28 [OSKMNL]) with immune evasion mRNAs (E3, K3, and B18R [EKB]) from vaccinia virus. Additionally, we included mature, double-stranded microRNAs (miRNAs) from the 302/367 cluster, which are known to enhance the reprogramming process, to develop a robust reprogramming protocol for the generation of stable iPS cell lines from both human fibroblasts and human blood-outgrowth endothelial progenitor cells (EPCs). Our novel combination of RNAs enables the cell to tolerate repetitive transfections for the generation of stable iPS cell colonies from human fibroblasts within 11 days while requiring only four transfections. Moreover, our method resulted in the first known mRNA-vectored reprogramming of human blood-derived EPCs within 10 days while requiring only eight daily transfections.

7q11.23 dosage-dependent dysregulation in human pluripotent stem cells affects transcriptional programs in disease-relevant lineages.

Cell reprogramming promises to make characterization of the impact of human genetic variation on health and disease experimentally tractable by enabling the bridging of genotypes to phenotypes in developmentally relevant human cell lineages. Here we apply this paradigm to two disorders caused by symmetrical copy number variations of 7q11.23, which display a striking combination of shared and symmetrically opposite phenotypes--Williams-Beuren syndrome and 7q-microduplication syndrome. Through analysis of transgene-free patient-derived induced pluripotent stem cells and their differentiated derivatives, we find that 7q11.23 dosage imbalance disrupts transcriptional circuits in disease-relevant pathways beginning in the pluripotent state. These alterations are then selectively amplified upon differentiation of the pluripotent cells into disease-relevant lineages. A considerable proportion of this transcriptional dysregulation is specifically caused by dosage imbalances in GTF2I, which encodes a key transcription factor at 7q11.23 that is associated with the LSD1 repressive chromatin complex and silences its dosage-sensitive targets.

Central nervous system disposition and metabolism of Fosdevirine (GSK2248761), a non-nucleoside reverse transcriptase inhibitor: an LC-MS and Matrix-assisted laser desorption/ionization imaging MS investigation into central nervous system toxicity.

The CNS disposition and metabolism of Fosdevirine (FDV), an HIV non-nucleoside reverse transcriptase inhibitor, was investigated in four patients who unexpectedly experienced seizures after at least 4 weeks of treatment in a Phase IIb, HIV-1 treatment experienced study. In addition, the CNS disposition and metabolism of FDV was examined in samples from rabbit, minipig, and monkey studies. LC-MS was used to characterize and estimate the concentrations of FDV and its metabolites in cerebral spinal fluid (seizure patients, rabbit, and monkey) and brain homogenate (rabbit, minipig, and monkey). The application of matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) provided the spatial distribution of FDV and its metabolites in brain tissue (rabbit, minipig, and monkey). A cysteine conjugate metabolite resulting from an initial glutathione (GSH) Michael addition to the trans-phenyl acrylonitrile moiety of FDV was the predominant drug-related component in the samples from seizure patients, rabbits, and minipigs. This metabolite persisted in the CNS for an extended period of time after the last dose in both seizure patients and minipigs. Furthermore, the localization of this metabolite was found to be highly associated with the white matter in rabbit and minipig brain sections by MALDI IMS. In contrast, the predominant component in monkey CNS was FDV, which was shown to be highly associated with the gray matter. On the basis of these data, several hypothesizes are considered, which might provide insights into species differences in CNS toxicity/seizures observed after FDV dosing.

Generation of induced pluripotent stem cells by reprogramming human fibroblasts with the stemgent human TF lentivirus set.

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing the pluripotent state in mouse fibroblasts.(1) The same group also reported the successful reprogramming of human somatic cells into induced pluripotent stem (iPS) cells using human versions of the same transcription factors delivered by retroviral vectors.(2) Additionally, James Thomson et al. reported that the lentivirus-mediated co-expression of another set of factors (Oct4, Sox2, Nanog and Lin28) was capable of reprogramming human somatic cells into iPS cells.(3) iPS cells are similar to ES cells in morphology, proliferation and the ability to differentiate into all tissue types of the body. Human iPS cells have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. The generation of patient-specific iPS cells circumvents an important roadblock to personalized regenerative medicine therapies by eliminating the potential for immune rejection of non-autologous transplanted cells. Here we demonstrate the protocol for reprogramming human fibroblast cells using the Stemgent Human TF Lentivirus Set. We also show that cells reprogrammed with this set begin to show iPS morphology four days post-transduction. Using the Stemolecule Y27632, we selected for iPS cells and observed correct morphology after three sequential rounds of colony picking and passaging. We also demonstrate that after reprogramming cells displayed the pluripotency marker AP, surface markers TRA-1-81, TRA-1-60, SSEA-4, and SSEA-3, and nuclear markers Oct4, Sox2 and Nanog.

Generation of induced pluripotent stem cells by reprogramming mouse embryonic fibroblasts with a four transcription factor, doxycycline inducible lentiviral transduction system.

Using a defined set of transcription factors and cell culture conditions, Yamanaka and colleagues demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc, and Klf4 is capable of inducing pluripotency in mouse fibroblasts.(1) Subsequent reports have demonstrated the utility of the doxycycline (DOX) inducible lentiviral delivery system for the generation of both primary and secondary iPS cells from a variety of other adult mouse somatic cell types.(2,3) Induced pluripotent stem (iPS) cells are similar to embryonic stem (ES) cells in morphology, proliferation and ability to induce teratoma formation. Both types of cell can be used as the pluripotent starting material for the generation of differentiated cells or tissues in regenerative medicine.(4-6) iPS cells also have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. Here we demonstrate the protocol for reprogramming mouse embryonic fibroblast (MEF) cells with the Stemgent DOX Inducible Mouse TF Lentivirus Set. We also demonstrate that the Stemgent DOX Inducible Mouse TF Lentivirus Set is capable of expressing each of the four transcription factors upon transduction into MEFs thereby inducing a pluripotent stem cell state that displays the pluripotency markers characteristic of ES cells.