Mesenchymal stromal/stem cells (MSCs) possess immunomodulatory and reparative properties. Through specific interactions with immune cells that participate in both innate and adaptive responses, MSCs exposed to an inflammatory microenvironment can downregulate many immune effector functions. Clinical trials focusing on MSCs to treat graft-versus-host disease (GvHD) and autoimmune diseases are underway. Current analyses suggest that MSCs will improve cell and solid organ transplantation by ameliorating rejection and possibly eliminating the requirement for prolonged regimens of conventional immunosuppressive drugs. This review examines the in vitro and in vivo evidence for the clinical use of bone marrow derived MSCs.

Induced pluripotent stem (iPS) cells offer a unique potential for understanding the molecular basis of disease and development. Here we have generated several human iPS cell lines, and we describe their pluripotent phenotype and ability to differentiate into erythroid cells, monocytes, and endothelial cells. More significantly, however, when these iPS cells were differentiated under conditions that promote lympho-hematopoiesis from human embryonic stem cells, we observed the formation of pre-B cells. These cells were CD45 ؉ CD19 ؉ CD10 ؉ and were positive for transcripts Pax5, IL7␣R, -like, and VpreB receptor. Although they were negative for surface IgM and CD5 expression, iPS-derived CD45 ؉ CD19 ؉ cells also exhibited multiple genomic D-J H rearrangements, which supports a pre-B-cell identity. We therefore have been able to demonstrate, for the first time, that human iPS cells are able to undergo hematopoiesis that contributes to the B-cell lymphoid lineage. (Blood. 2011;117(15): 4008-4011) IntroductionReprogramming of adult human somatic cells toward induced pluripotent stem cells 1-3 is a groundbreaking technology that opens the way for the development of novel diagnostics and therapeutics. Although traditionally human embryonic stem (hES) cells have been used as a convenient tool with which to understand hematopoietic and lymphoid development in health and disease, the usefulness of human induced pluripotent stem (iPS) cells for this purpose has recently been questioned. 4 For hES cells, a limited number of studies have derived B cells 5 and T cells, 6,7 with some reports suggesting why this might be difficult to achieve, 8 and which has not been described thus far for B cells from human iPS cells. Development of lymphoid progenitors from such pluripotent sources is of particular interest because it will help to understand better the early stages of B-cell development, which is currently not well understood. 9 This includes which B cells are formed and when and how these lineages relate to the formation of both normal and leukemic progenitors during development. 10,11 Methods Derivation, identification, and maintenance of human iPS cell lines iPS cells were generated essentially as decided by Takahashi et al, 1 with changes highlighted herein. pMX vectors hOct4, hSox2, and hKlf4 were purchased from Addgene and viral supernantants for each transgene produced in pantropic PLATGP packaging cells (Cell Biolabs). Transduced Normal Human Dermal Fibroblasts (NHDFs; Lonza Biologics) were cocultured with mitomycin C-treated mouse embryonic fibroblasts in modified embryonic stem cell media (Dulbecco modified Eagle medium/ F12, 20% [v/v] Knock Out Serum Replacement, 10 ng/mL basic fibroblast growth factor, 2mM sodium pyruvate, 1ϫ nonessential amino acids [Invitrogen], and 1M mercaptoethanol [Sigma-Aldrich]). Cultures were routinely maintained in 5% CO 2 and 5% oxygen with half-media changes every 2 days, for up to 34 days. iPS colonies were picked and expanded before adaptation to feeder independent culture as describ...

Induced pluripotent stem cells (iPSCs) have the potential to transform drug discovery and healthcare in the 21(st) century. However, successful commercialization will require standardized manufacturing platforms. Here we highlight the need to define standardized practices for iPSC generation and processing and discuss current challenges to the robust manufacture of iPSC products.

The differentiation of human pluripotent stem cells to the B-cell lymphoid lineage has important clinical applications that include in vitro modeling of developmental lymphogenesis in health and disease. Here, we first demonstrate the capacity of human induced pluripotent stem cells (hiPSCs) to differentiate into CD144(+)CD73(-)CD43/CD235a(-) cells, characterized as hemogenic endothelium, and show that this population is capable of differentiating to CD10(+)CD19(+) B lymphocytes. We also demonstrate that B lymphocytes generated from hiPSCs are able to undergo full VDJ rearrangement and express surface IgM (sIgM(+)), thus representing an immature B-cell subset. Efficiency of sIgM expression on the hiPSC-derived B lymphocytes (∼ 5% of CD19(+) cells) was comparable with B lymphocytes generated from human umbilical cord blood (UCB) hematopoietic progenitor cells. Importantly, when assessed by global transcriptional profiling, hiPSC-derived B-cells show a very high level of similarity when compared with their UCB-derived counterparts, such that from more than 47,000 different transcripts, only 45 were significantly different (with a criteria adjusted P value P<0.05, log FC >1.5 or 2.8-fold). This represents a unique in vitro model to delineate critical events during lymphogeneisis in development and lymphoid diseases such as acute lymphocytic leukemia.

Novice and expert skill levels of unobserved trials can be discerned using a state vector machine trained with parameters based on the isogony principle. The accuracy of this classification comes within 90% of the classification accuracy from observing the full trial within 10 s of task initiation on average.

Human induced pluripotent stem cells (hiPSCs), like embryonic stem cells, are under intense investigation for novel approaches to model disease and for regenerative therapies. Here, we describe the derivation and characterization of hiPSCs from a variety of sources and show that, irrespective of origin or method of reprogramming, hiPSCs can be differentiated on OP9 stroma towards a multi-lineage haemo-endothelial progenitor that can contribute to CD144+ endothelium, CD235a+ erythrocytes (myeloid lineage) and CD19+ B lymphocytes (lymphoid lineage). Within the erythroblast lineage, we were able to demonstrate by single cell analysis (flow cytometry), that hiPSC-derived erythroblasts express alpha globin as previously described, and that a sub-population of these erythroblasts also express haemoglobin F (HbF), indicative of fetal definitive erythropoiesis. More notably however, we were able to demonstrate that a small sub-fraction of HbF positive erythroblasts co-expressed HbA in a highly heterogeneous manner, but analogous to cord blood-derived erythroblasts when cultured using similar methods. Moreover, the HbA expressing erythroblast population could be greatly enhanced (44·0 ± 6·04%) when a defined serum-free approach was employed to isolate a CD31+ CD45+ erythro-myeloid progenitor. These findings demonstrate that hiPSCs may represent a useful alternative to standard sources of erythrocytes (RBCs) for future applications in transfusion medicine.

There is a need for physical standards (reference materials) to ensure both reproducibility and consistency in the production of somatic cell types from human pluripotent stem cell (hPSC) sources. We have outlined the need for reference materials (RMs) in relation to the unique properties and concerns surrounding hPSC-derived products and suggest in-house approaches to RM generation relevant to basic research, drug screening, and therapeutic applications. hPSCs have an unparalleled potential as a source of somatic cells for drug screening, disease modeling, and therapeutic application. Undefined variation and product variability after differentiation to the lineage or cell type of interest impede efficient translation and can obscure the evaluation of clinical safety and efficacy. Moreover, in the absence of a consistent population, data generated from in vitro studies could be unreliable and irreproducible. Efforts to devise approaches and tools that facilitate improved consistency of hPSC-derived products, both as development tools and therapeutic products, will aid translation. Standards exist in both written and physical form; however, because many unknown factors persist in the field, premature written standards could inhibit rather than promote innovation and translation. We focused on the derivation of physical standard RMs. We outline the need for RMs and assess the approaches to in-house RM generation for hPSC-derived products, a critical tool for the analysis and control of product variation that can be applied by researchers and developers. We then explore potential routes for the generation of RMs, including both cellular and noncellular materials and novel methods that might provide valuable tools to measure and account for variation. Multiparametric techniques to identify "signatures" for therapeutically relevant cell types, such as neurons and cardiomyocytes that can be derived from hPSCs, would be of significant utility, although physical RMs will be required for clinical purposes.

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