Differential requirements for hematopoietic commitment between human and rhesus embryonic stem cells

Rhesus iPSC Safe Harbor Gene-Editing Platform for Stable Expression of Transgenes in Differentiated Cells of All Germ Layers

Nonhuman primate (NHP) induced pluripotent stem cells (iPSCs) offer the opportunity to investigate the safety, feasibility, and efficacy of proposed iPSC-derived cellular delivery in clinically relevant in vivo models. However, there is need for stable, robust, and safe labeling methods for NHP iPSCs and their differentiated lineages to study survival, proliferation, tissue integration, and biodistribution following transplantation. Here we investigate the utility of the adeno-associated virus integration site 1 (AAVS1) as a safe harbor for the addition of transgenes in our rhesus macaque iPSC (RhiPSC) model. A clinically relevant marker gene, human truncated CD19 (hΔCD19), or GFP was inserted into the AAVS1 site in RhiPSCs using the CRISPR/Cas9 system. Genetically modified RhiPSCs maintained normal karyotype and pluripotency, and these clones were able to further differentiate into all three germ layers in vitro and in vivo. In contrast to transgene delivery using randomly integrating viral vectors, AAVS1 targeting allowed stable transgene expression following differentiation. Off-target mutations were observed in some edited clones, highlighting the importance of careful characterization of these cells prior to downstream applications. Genetically marked RhiPSCs will be useful to further advance clinically relevant models for iPSC-based cell therapies.

Establishment of a translational endothelial cell model using directed differentiation of induced pluripotent stem cells from Cynomolgus monkey

Due to their broad differentiation potential, pluripotent stem cells (PSCs) offer a promising approach for generating relevant cellular models for various applications. While human PSC-based cellular models are already advanced, similar systems for non-human primates (NHPs) are still lacking. However, as NHPs are the most appropriate animals for evaluating the safety of many novel pharmaceuticals, the availability of in vitro systems would be extremely useful to bridge the gap between cellular and animal models. Here, we present a NHP in vitro endothelial cell system using induced pluripotent stem cells (IPSCs) from Cynomolgus monkey (Macaca fascicularis). Based on an adapted protocol for human IPSCs, we directly differentiated macaque IPSCs into endothelial cells under chemically defined conditions. The resulting endothelial cells can be enriched using immuno-magnetic cell sorting and display endothelial marker expression and function. RNA sequencing revealed that the differentiation process closely resembled vasculogenesis. Moreover, we showed that endothelial cells derived from macaque and human IPSCs are highly similar with respect to gene expression patterns and key endothelial functions, such as inflammatory responses. These data demonstrate the power of IPSC differentiation technology to generate defined cell types for use as translational in vitro models to compare cell type-specific responses across species.

GSK3β Inhibition Promotes Efficient Myeloid and Lymphoid Hematopoiesis from Non-human Primate-Induced Pluripotent Stem Cells

Advances in the scalable production of blood cells from induced pluripotent stem cells (iPSCs) open prospects for the clinical translation of de novo generated blood products, and evoke the need for preclinical evaluation of their efficacy, safety, and immunogenicity in large animal models. Due to substantial similarities with humans, the outcomes of cellular therapies in non-human primate (NHP) models can be readily extrapolated to a clinical setting. However, the use of this model is hampered by relatively low efficiency of blood generation and lack of lymphoid potential in NHP-iPSC differentiation cultures. Here, we generated transgene-free iPSCs from different NHP species and showed the efficient induction of mesoderm, myeloid, and lymphoid cells from these iPSCs using a GSK3β inhibitor. Overall, our studies enable scalable production of hematopoietic progenitors from NHP-iPSCs, and lay the foundation for preclinical testing of iPSC-based therapies for blood and immune system diseases in an NHP model.

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Generation of transgene-free iPSCs from various non-human primate (NHP) species

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GSK3β inhibition is essential for induction of mesoderm and blood from NHP-iPSCs

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Efficient generation of CD34⁺CD45⁺CD90⁺CD38⁻CD45RA⁻ progenitors from NHP-iPSCs

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Efficient T and NK cell production from NHP-iPSCs

Alternative methods in toxicology: CFU assays application, limitation and future prospective

Blood is a fluid connective tissue which plays a vital role for normal body function. It consist different type of blood cells which is continuously reproduce inside the bone marrow from hematopoietic system. Xenobiotics could be specifically toxic to the hematopoietic system and they can cause hematological disorders by disturbing the normal functions. In vitro hematopoietic colony-forming cell assays play a crucial role to evaluate potential toxic effects of new xenobiotics and also helpful in bridging the gap between preclinical toxicology studies in animal models and clinical investigations. Use of these assays in conjunction with, high-throughput screening reduces the cost and time associated with these assays. This article provides a critical view over in vitro hematopoietic colony-forming cell assays in assessment of hematotoxicity.

Identification of a cross-reacting, monoclonal anti-human CD233 antibody for identification and sorting of rhesus macaque erythrocytes

Erythroid biology research involving rhesus macaques has been applied to several topics including malaria, hemoglobinopathy and gene therapy research. However, analyses of the rhesus red blood cells are limited by the inability to identify and sort those cells in research blood samples using flow cytometry. Here it is reported that the BRIC 6 hybridoma clone raised to the human erythroid surface molecule (referred to as CD233, Band 3, AE1, or SLC4A1) produces cross-reactive and erythroid-specific antibodies for flow cytometric detection and sorting of rhesus macaque erythrocytes.

Interspecies chimera between primate embryonic stem cells and mouse embryos: monkey ESCs engraft into mouse embryos, but not post-implantation fetuses

Unequivocal evidence for pluripotency in which embryonic stem cells contribute to chimeric offspring has yet to be demonstrated in human or nonhuman primates (NHPs). Here, rhesus and baboons ESCs were investigated in interspecific mouse chimera generated by aggregation or blastocyst injection. Aggregation chimera produced mouse blastocysts with GFP-nhpESCs at the inner cell mass (ICM), and embryo transfers (ETs) generated dimly-fluorescencing abnormal fetuses. Direct injection of GFP-nhpESCs into blastocysts produced normal non-GFP-fluorescencing fetuses. Injected chimera showed >70% loss of GFP-nhpESCs after 21 h culture. Outgrowths of all chimeric blastocysts established distinct but separate mouse- and NHP-ESC colonies. Extensive endogenous autofluorescence compromised anti-GFP detection and PCR analysis did not detect nhpESCs in fetuses. NhpESCs localize to the ICM in chimera and generate pregnancies. Because primate ESCs do not engraft post-implantation, and also because endogenous autofluorescence results in misleading positive signals, interspecific chimera assays for pluripotency with primate stem cells is unreliable with the currently available ESCs. Testing primate ESCs reprogrammed into even more naïve states in these inter-specific chimera assays will be an important future endeavor.

Assisted Reproductive Technologies (ART) with baboons generate live offspring: a nonhuman primate model for ART and reproductive sciences

Human reproduction has benefited significantly by investigating nonhuman primate (NHP) models, especially rhesus macaques. To expand the Old World monkey species available for human reproductive studies, we present protocols in baboons, our closest Old World primate relatives, for assisted reproductive technologies (ART) leading to live born offspring. Baboons complement rhesus by confirming or modifying observations generated in humans often obtained by the study of clinically discarded specimens donated by anonymous infertility patient couples. Here, baboon ART protocols, including oocyte collection, in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), preimplantation development to blastocyst stage, and embryo transfer techniques are described. With baboon ART methodologies in place, motility during baboon fertilization was investigated by time-lapse video microscopy (TLVM). The first ART baboons produced by ICSI, a pair of male twins, were delivered naturally at 165 days postgestation. Genetic testing of these twins confirmed their ART parental origins and demonstrated that they are unrelated fraternal twins not identicals. These results have implications for ART outcomes, embryonic stem cell (ESC) derivation, and reproductive sciences.

Comparison of human fetal liver, umbilical cord blood, and adult blood hematopoietic stem cell engraftment in NOD-scid/gammac-/-, Balb/c-Rag1-/-gammac-/-, and C.B-17-scid/bg immunodeficient mice

Immunodeficient mice bearing components of a human immune system present a novel approach for studying human immune responses. We investigated the number, phenotype, developmental kinetics, and function of developing human immune cells following transfer of CD34(+) hematopoietic stem cell (HSC) preparations originating from second trimester human fetal liver (HFL), umbilical cord blood (UCB), or granulocyte colony-stimulating factor-mobilized adult blood (G-CSF-AB) delivered via intrahepatic injection into sublethally irradiated neonatal NOD-scid/gammac(-/-), Balb/c-Rag1(-/-)gammac(-/-), and C.B-17-scid/bg mice. HFL and UCB HSC provided the greatest number and breadth of developing cells. NOD-scid/gammac(-/-) and Balb/c-Rag1(-/-)gammac(-/-) harbored human B and dendritic cells as well as human platelets in peripheral blood, whereas NOD-scid/gammac(-/-) mice harbored higher levels of human T cells. NOD-scid/gammac(-/-) mice engrafted with HFL CD34(+) HSC demonstrated human immunological competence evidenced by white pulp expansion and increases in total human immunoglobulin following immunization with T-dependent antigens and delayed-type hypersensitivity-infiltrating leukocytes in response to antigenic challenge. In conclusion, we describe an encouraging base system for studying human hematopoietic lineage development and function utilizing human HFL or UCB HSC-engrafted NOD-scid/gammac(-/-) mice that is well suited for future studies toward the development of a fully competent humanized mouse model.

Establishment and characterization of baboon embryonic stem cell lines: an Old World Primate model for regeneration and transplantation research

Here we have developed protocols using the baboon as a complementary alternative Old World Primate to rhesus and other macaques which have severe limitations in their availability. Baboons are not limited as research resources, they are evolutionarily closer to humans, and the multiple generations of pedigreed colonies which display complex human disease phenotypes all support their further optimization as an invaluable primate model. Since neither baboon-assisted reproductive technologies nor baboon embryonic stem cells (ESCs) have been reported, here we describe the first derivations and characterization of baboon ESC lines from IVF-generated blastocysts. Two ESCs lines (BabESC-4 and BabESC-15) display ESC morphology, express pluripotency markers (Oct-4, hTert, Nanog, Sox-2, Rex-1, TRA1-60, TRA1-81), and maintain stable euploid female karyotypes with parentage confirmed independently. They have been grown continuously for >430 and 290 days, respectively. Teratomas from both lines have all three germ layers. Availabilities of these BabESCs represent another important resource for stem cell biologists.

Diverse hematopoietic potentials of five human embryonic stem cell lines

Despite a growing body of literature concerning the hematopoietic differentiation of human embryonic stem cells (hESCs), the full hematopoietic potential of the majority of existing hESC lines remains unknown. In this study, the hematopoietic response of five NIH-approved hESC lines (H1, hSF6, BG01, BG02, and BG03) was compared. Our data show that despite expressing similar hESC markers under self-renewing conditions and initiating mesodermal differentiation under spontaneous differentiation conditions, marked differences in subsequent hematopoietic differentiation potential among these lines existed. A high degree of hematopoietic differentiation was attained only by H1 and BG02, whereas this process appeared to be abortive in nature for hSF6, BG01, and BG03. This difference in hematopoietic differentiation predisposition was readily apparent during spontaneous differentiation, and further augmented under hematopoietic-inducing conditions. This predisposition appeared to be intrinsic to the specific hESC line and independent of passage number or gender karyotype. Interestingly, H1 and BG02 displayed remarkable similarities in their kinetics of hematopoietic marker expression, hematopoietic colony formation, erythroid differentiation, and globin expression, suggesting that a similar, predetermined differentiation sequence is followed. The identification of intrinsic and extrinsic factors governing the hematopoietic differentiation potential of hESCs will be of great importance for the putative clinical utility of hESC lines.