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Despite therapeutic advances, neurodegenerative diseases and disorders remain some of the leading causes of mortality and morbidity in the United States. Therefore, cell-based therapies to replace lost or damaged neurons and supporting cells of the central nervous system (CNS) are of great therapeutic interest. To that end, human pluripotent stem cells (hPSC) derived neural progenitor cells (hNPCs) and their neuronal derivatives could provide the cellular ‘raw material’ needed for regenerative medicine therapies for a variety of CNS disorders. In addition, hNPCs derived from patient-specific hPSCs could be used to elucidate the underlying mechanisms of neurodegenerative diseases and identify potential drug candidates. However, the scientific and clinical application of hNPCs requires the development of robust, defined, and scalable substrates for their long-term expansion and neuronal differentiation. In this study, we rationally designed a vitronectin-derived peptide (VDP) that served as an adhesive growth substrate for the long-term expansion of several hNPC lines. Moreover, VDP-coated surfaces allowed for the directed neuronal differentiation of hNPC at levels similar to cells differentiated on traditional extracellular matrix protein-based substrates. Overall, the ability of VDP to support the long-term expansion and directed neuronal differentiation of hNPCs will significantly advance the future translational application of these cells in treating injuries, disorders, and diseases of the CNS.

Expression of doublecortin (DCX), a 43-53 kDa microtubule binding protein, is frequently used as (i) an early neuronal marker to identify the stage of neuronal maturation of in vivo grafted neuronal precursors (NSCs), and (ii) a neuronal fate marker transiently expressed by immature neurons during development. Reliable identification of the origin of DCX-immunoreactive cells (i.e., host vs. graft) requires detailed spatial and temporal mapping of endogenous DCX expression at graft-targeted brain or spinal cord regions. Accordingly, in the present study, we analyzed (i) the time course of DCX expression in pre- and postnatal rat and porcine spinal cord, and (ii) the DCX expression in spinally grafted porcine-induced pluripotent stem cells (iPS)-derived NSCs and human embryonic stem cell (ES)-derived NSCs. In addition, complementary temporospatial GFAP expression study in porcine spinal cord was also performed. In 21-day-old rat fetuses, an intense DCX immunoreactivity distributed between the dorsal horn (DH) and ventral horn was seen and was still present in the DH neurons on postnatal day 20. In animals older than 8 weeks, no DCX immunoreactivity was seen at any spinal cord laminae. In contrast to rat, in porcine spinal cord (gestational period 113-114 days), DCX was only expressed during the pre-natal period (up to 100 days) but was no longer present in newborn piglets or in adult animals. Immunohistochemical analysis was confirmed with a comparable expression profile by western blot analysis. Contrary, the expression of porcine GFAP started within 70-80 days of the pre-natal period. Spinally grafted porcine iPS-NSCs and human ES-NSCs showed clear DCX expression at 3-4 weeks postgrafting. These data indicate that in spinal grafting studies which employ postnatal or adult porcine models, the expression of DCX can be used as a reliable marker of grafted neurons. In contrast, if grafted neurons are to be analyzed during the first 4 postnatal weeks in the rat spinal cord, additional markers or grafted cell-specific labeling techniques need to be employed to reliably identify grafted early postmitotic neurons and to differentiate the DCX expression from the neurons of the host.

An important component for successful translation of cell replacement-based therapies into clinical practice is the utilization of large animal models to conduct efficacy and/or safety cell dosing studies. Over the past few decades, several large animal models (dog, cat, nonhuman primate) were developed and employed in cell replacement studies; however, none of these models appears to provide a readily available platform to conduct effective and large-scale preclinical studies. In recent years, numerous pig models of neurodegenerative disorders were developed using both a transgenic approach as well as invasive surgical techniques. The pig model (naive noninjured animals) was recently used successfully to define the safety and optimal dosing of human spinal stem cells after grafting into the central nervous system (CNS) in immunosuppressed animals. The data from these studies were used in the design of a human clinical protocol used in amyotrophic lateral sclerosis (ALS) patients in a Phase I clinical trial. In addition, a highly inbred (complete major histocompatibility complex [MHC] match) strain of miniature pigs is available which permits the design of comparable MHC combinations between the donor cells and the graft recipient as used in human patients. Jointly, these studies show that the pig model can represent an effective large animal model to be used in preclinical cell replacement modeling. This review summarizes the available pig models of neurodegenerative disorders and the use of some of these models in cell replacement studies. The challenges and potential future directions in more effective use of the pig neurodegenerative models are also discussed. J. Comp. Neurol. 522:2784–2801, 2014. © 2014 Wiley Periodicals, Inc.

Cell cycle represents not only a tightly orchestrated mechanism of cell replication and cell division but it also plays an important role in regulation of cell fate decision. Particularly in the context of pluripotent stem cells or multipotent progenitor cells, regulation of cell fate decision is of paramount importance. It has been shown that human embryonic stem cells (hESCs) show unique cell cycle characteristics, such as short doubling time due to abbreviated G1 phase; these properties change with the onset of differentiation. This review summarizes the current understanding of cell cycle regulation in hESCs. We discuss cell cycle properties as well as regulatory machinery governing cell cycle progression of undifferentiated hESCs. Additionally, we provide evidence that long-term culture of hESCs is accompanied by changes in cell cycle properties as well as configuration of several cell cycle regulatory molecules.

The controlled in vitro differentiation of human embryonic stem cells (hESCs) and other pluripotent stem cells provides interesting prospects for generating large numbers of human neurons for a variety of biomedical applications. A major bottleneck associated with this approach is the long time required for hESC-derived neural cells to give rise to mature neuronal progeny. In the developing vertebrate nervous system, Notch signaling represents a key regulator of neural stem cell (NSC) maintenance. Here, we set out to explore whether this signaling pathway can be exploited to modulate the differentiation of hESC-derived NSCs (hESNSCs). We assessed the expression of Notch pathway components in hESNSCs and demonstrate that Notch signaling is active under self-renewing culture conditions. Inhibition of Notch activity by the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) in hESNSCs affects the expression of human homologues of known targets of Notch and of several cell cycle regulators. Furthermore, DAPT-mediated Notch inhibition delays G1/S-phase transition and commits hESNSCs to neurogenesis. Combined with growth factor withdrawal, inhibition of Notch signaling results in a marked acceleration of differentiation, thereby shortening the time required for the generation of electrophysiologically active hESNSC-derived neurons. This effect can be exploited for neural cell transplantation, where transient Notch inhibition before grafting suffices to promote the onset of neuronal differentiation of hESNSCs in the host tissue. Thus, interference with Notch signaling provides a tool for controlling human NSC differentiation both in vitro and in vivo.

Stem cell research began in the 1950s with the study of teratocarcinomas. Stevens and Little determined that these malignant germ-cell tumors comprise undifferentiated cell components (so-called embryonal carcinoma cells, or EC cells) that have the ability to form entirely new teratocarcinomas upon transplantation into experimental animals. In 1964, Lewis Kleinsmith and Barry Pierce demonstrated that a single EC cell is capable of multilineage differentiation as well as unlimited self-renewal—the two key characteristics of stem cells. Later, mouse EC cell lines that can be stably propagated in vitro were established, and several EC cell lines were shown to form chimeras upon injection into mouse blastocysts. Naturally, similar developmental properties of EC cells and early embryonic cells led to a search for a karyotypically stable counterpart of these cells. In the early 1980s, two groups simultaneously introduced the first pluripotent mouse embryonic stem cells to the scientific community.

An important component for successful translation of cell replacement-based therapies into clinical practice is the utilization of large animal models to conduct efficacy and/or safety cell dosing studies. Over the past few decades, several large animal models (dog, cat, nonhuman primate) were developed and employed in cell replacement studies; however, none of these models appears to provide a readily available platform to conduct effective and large-scale preclinical studies. In recent years, numerous pig models of neurodegenerative disorders were developed using both a transgenic approach as well as invasive surgical techniques. The pig model (naïve noninjured animals) was recently used successfully to define the safety and optimal dosing of human spinal stem cells after grafting into the central nervous system (CNS) in immunosuppressed animals. The data from these studies were used in the design of a human clinical protocol used in amyotrophic lateral sclerosis (ALS) patients in a Phase I clinical trial. In addition, a highly inbred (complete major histocompatibility complex [MHC] match) strain of miniature pigs is available which permits the design of comparable MHC combinations between the donor cells and the graft recipient as used in human patients. Jointly, these studies show that the pig model can represent an effective large animal model to be used in preclinical cell replacement modeling. This review summarizes the available pig models of neurodegenerative disorders and the use of some of these models in cell replacement studies. The challenges and potential future directions in more effective use of the pig neurodegenerative models are also discussed.

Studies of human embryonic stem cells (hESCs) commonly describe the nonfunctional p53-p21 axis of the G1/S checkpoint pathway with subsequent relevance for cell cycle regulation and the DNA damage response (DDR). Importantly, p21 mRNA is clearly present and upregulated after the DDR in hESCs, but p21 protein is not detectable. In this article, we provide evidence that expression of p21 protein is directly regulated by the microRNA (miRNA) pathway under standard culture conditions and after DNA damage. The DDR in hESCs leads to upregulation of tens of miRNAs, including hESC-specific miRNAs such as those of the miR-302 family, miR-371-372 family, or C19MC miRNA cluster. Most importantly, we show that the hESC-enriched miRNA family miR-302 (miR-302a, miR-302b, miR-302c, and miR-302d) directly contributes to regulation of p21 expression in hESCs and, thus, demonstrate a novel function for miR-302s in hESCS. The described mechanism elucidates the role of miRNAs in regulation of important molecular pathway governing the G1/S transition checkpoint before as well as after DNA damage.

Abstract 3874 It is known that the biology of CLL and other B-cell malignancies is driven by processes dependent on immunoglobulin structure and BCR-signaling. Recently, our group and others have described the importance of miRNAs in CLL and their involvement in BCR-signaling, IgG production and V(D)J recombination. Considering the important functions of miRNAs it is remarkable that the human locus for immunoglobulin lambda light chain (IgL) contains a miR gene. The miR-650 gene is localized in exon 1 of IgL variable subgene (1st exon of V2 family members). The aim of this study was to reveal the regulation and expression of miR-650 in CLL and its relation to disease prognosis. CLL samples were separated by RosetteSep Human B Cell Enrichment Cocktail (obtained purity ≥95% of CD5+19+ cells). The expression of light chain surface immunoglobulin chain (lambda vs kappa) was determined by flow cytometry. The utilized IgL variable (V) segment was determined using BIOMED-2 protocol and sequencing. To study the relation of miR-650 expression and IgL rearrangement the surface expression of Ig light chain and the utilized V segment was determined in a CLL cohort containing 47 patients (λ n=27, κ n=19, λ+κ n=1). The gene expression was analyzed by TaqMan Assays (ABI) for mature miR-650 and protein-coding genes: CDK1, EBF3 and ING4. The western-blot for miR-650 targets was performed after transfection (48hrs/96hrs) of B-cell lines (NALM-6, MEC-1) with a short RNA mimicking miR-650 (Dharmacon). The analyses of miR-650 expression revealed that cells utilizing V2-8, V2-5, V2-14, V2-23 subgenes for IgL (n=14) had ∼10 fold higher expression of miR-650 (p We next studied the possible targets for miR-650 in B-cells. Recently, two targets were identified in solid tumors - ING4 (Inhibitor of Growth 4) and CDK1 (cyclin dependent kinase 1) (Zhang, 2010; Chien, 2010). It has been demonstrated that miR-650 is involved in the p16INK4-mediated pathway and directly regulates the CDK1. This publication suggested that up-regulation of miR-650 leads to inhibition of cell cycle progression. Moreover, the putative targets predicted by software tools (TargetScan, miRanda) include genes important for B-cell biology like EBF3 (early B-cell factor3), CLLU1, Bcl2 and cyclin D1. We therefore studied correlation between miR-650 expression and the expression of mRNAs for CDK1, ING4 and EBF3 (a predicted target with the highest score). The expression of miR-650 was not significantly associated with the expression of any of these genes on mRNA level. The lack of available material did not allow us to study the expression of CDK1, ING4, EBF3 protein levels in the original cohort. However, the transfection of B-cells with short RNA mimicking miR-650 led to down-regulation of protein levels of CDK1 and EBF3. This confirms the relevance of CDK1 as a target in B-cells and identifies a new target - EBF3, which is known to be important for B-cells development. Moreover, the expression of miR-650 was associated with overall survival (OS) and treatment free survival (TFS) in CLL (n=82). In this analysis patients were divided in two groups (based on the median of miR-650 expression). The higher expression of miR-650 was associated with statistically significant (p In conclusion, we have described a mechanism regulating miR-650 expression, identified its relevant targets in B-cells and demonstrated the association of miR-650 expression with CLL prognosis. Supported by IGA MZCR NT11218-6/2010, MSMTMSM0021622430, NS10439-3/2009, FR-TI2/254 Disclosures: Mayer: Roche: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Astellas: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Novartis: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Fresenius Medical Care: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Pfizer: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Genzyme: Consultancy, Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; GSK: Honoraria, Institutional/personal grants and travel/accommodation expenses, Speakers Bureau; Amgen:.