Human Embryonic Stem Cell-Derived CD34+ Cells Preferentially Develop into Endothelial Cells When Transplanted into Neonatal Immunodeficient Mice

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 69-69
Author(s):  
Xinghui Tian ◽  
Melinda K. Hexum ◽  
Vesselin R. Penchev ◽  
Russell J. Taylor ◽  
Leonard Shultz ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Endothelial Cells ◽  
Cord Blood ◽  
Embryonic Stem ◽  
Post Transplantation ◽  
Time Points ◽  
Bioluminescent Signal ◽  
Cd34 Cells

Abstract Selection for CD34+ cells from human bone marrow, umbilical cord blood and mobilized peripheral blood cells has been used to enrich for putative hematopoietic stem cells that are typically characterized by the ability to provide long-term multi-lineage engraftment after transplantation into NOD/SCID mice. In vitro studies have shown that CD34+ cells derived from human embryonic stem cells (hESC) have the similar capacity to develop into diverse mature blood cell lineages under defined conditions, though they may represent an even more primitive progenitor population with bi-potent ability to developed into both hematopoietic and endothelial cells. Previously, we and others have demonstrated in vivo hematopoietic engraftment of an unsorted heterogeneous population of differentiated hESC-derived cells injected into NOD/SCID mice. Here, to determine whether sorted CD34+ cells isolated from differentiated hESC have the equivalent SCID-repopulating potential, we directly delivered the CD34+ cells into the liver of neonatal NOD/SCID/gamma c (null) mice. Stable expression of firefly luciferase (luc) in the hESC derived-CD34+ cells allowed us to non-invasively track the engraftment patterns by in vivo bioluminescent imaging. Luc+ CD34+ cells were produced by co-culture of hESC with M2-10B4 mouse bone marrow-derived stromal cells. Each mouse (n=18) was injected with 2.5 – 9.4 × 10^5 CD34+ cells isolated at an early stage of differentiation (day 6–9 of co-culture). Successful injections were routinely confirmed by the bioluminescent signal detected in the liver at 1 week post-transplantation. There was typically a decrease of luc signal observed between 2–5 weeks post-transplantation, followed by the stabilizing and increasing of luc-expressing cells at later time points. Dramatic increase of bioluminescent signal in the livers was routinely demonstrated 8–12 weeks post-transplantation. The bioluminescence foci were initially maintained in the liver. Migration of luc+ cells from liver to bone marrow, spleen, kidney and mediastinum/thymus was also detected at later time points (10+ weeks post-transplantation). Flow cytometric analysis demonstrated a significant population of human HLA-class I+ cells (0.1–5.35%) in the engrafted livers (11 out of 15 mice), with the majority of the human CD34+CD31+ endothelial cells (0.03–4.78%). In most of cases, these endothelial cells also co-expressed CD73. No human CD45+ cells were found in any of the tissues evaluated. This is in contrast to CD34+ cells obtained from human cord blood utilized as a positive control cell populations that routinely demonstrated high levels of CD45+ cells (86.92±10.5%) of diverse hematopoietic lineages in the liver when transplanted in this model. Immunohistochemical staining showed that the hESC-derived CD34+CD31+ cells localized in vessels of the engrafted liver. Remarkably, the hESC-derived luc+CD34+CD31+ cells could be isolated several months post-transplant and re-cultured to clearly demonstrate typical endothelial cell characteristics including expression of vonWillebrand factor and VE-Cadherin, taking up of ac-LDL, and formation of capillary-like tubes when cultured in Matrigel. Additionally, ex vivo imaging of the exercised spleens and their surrounding connective tissues demonstrated luc+ cells located in the surrounding connective/mesenchymal tissues. Similar luc+ mesenchymal tissues were also found around the kidneys. Importantly, no visible teratomas were found in any of the transplanted mice. Together, these results demonstrate hESC-derived CD34+ cells preferentially develop into endothelial cells after transplantation into the fetal liver environment, with some additional development of mesenchymal tissues, but minimal hematopoietic cells. These studies demonstrate hESC-derived CD34+ cells are suitable for in vivo models to correct of vascular disease and further studies are underway to define signals required for improved hematopoietic engraftment of purified hESC-derived CD34+ cells.

Induced Hematopoietic Differentiation Of Common Marmoset Embryonic Stem Cells By LYL1 Can Give Rise To Hematopoietic Stem Cells Having The Enhanced Bone Marrow Reconstitution Capability

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1192-1192
Author(s):  
Hirotaka Kawano ◽  
Tomotoshi Marumoto ◽  
Takafumi Hiramoto ◽  
Michiyo Okada ◽  
Tomoko Inoue ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Lymphoblastic Leukemia ◽  
Embryonic Stem ◽  
Hematopoietic Differentiation ◽  
Hematopoietic Stem ◽  
Cd34 Cells ◽  
Hsc Transplantation

Abstract Hematopoietic stem cell (HSC) transplantation is the most successful cellular therapy for the malignant hematopoietic diseases such as leukemia, and early recovery of host’s hematopoiesis after HSC transplantation has eagerly been expected to reduce the regimen related toxicity for many years. For the establishment of the safer and more efficient cell source for allogeneic or autologous HSC transplantation, HSCs differentiated from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) that show indefinite proliferation in an undifferentiated state and pluripotency, are considered to be one of the best candidates. Unfortunately, despite many recent efforts, the HSC-specific differentiation from ESCs and iPSCs remains poor [Kaufman, DS et al., 2001][Ledran MH et al., 2008]. In this study, we developed the new method to differentiate HSC from non-human primate ESC/iPSC. It has been reported that common marmoset (CM), a non-human primate, is a suitable experimental animal for the preclinical studies of HSC therapy [Hibino H et al., 1999]. We have been investigated the hematopoietic differentiation of CM ESCs into HSCs, and previously reported that the induction of CD34+ cells having a blood colony forming capacity from CM ESCs were promoted by lentiviral transduction of TAL1 cDNA [Kurita R et al., 2006]. However, those CD34+ cells did not have a bone marrow reconstituting ability in irradiated NOG (NOD/Shi-scid/IL-2Rγnull) mice, suggesting that transduction of TAL1 gene was not sufficient to induce functional HSCs which have self-renewal capability and multipotency. Thus, we tried to find other hematopoietic genes being able to promote hematopoietic differetiation more efficiently than TAL1. We selected 6 genes (LYL1, HOXB4, BMI1, GATA2, c-MYB and LMO2) as candidates for factors that induce the differentiation of ESCs into HSCs, based on the previous study of hematopoietic differentiation from human and mouse ESCs. And CM ESCs (Cj11) lentivirally transduced with the respective candidate gene were processed for embryoid body (EB) formation to induce their differentiation into HSCs for 9 days. We found that lentiviral transduction of LYL1 (lymphoblastic leukemia 1), a basic helix-loop-helix transcription factor, in EBs markedly increased the proportion of cells positive for CD34 (approximately 20% of LYL1-transduced cells). RT-PCR showed that LYL1-transduced EBs expressed various hematopoietic genes, such as TAL1, RUNX1 and c-KIT. To examine whether these CD34+ cells have the ability to differentiate into hematopoietic cells in vitro, we performed colony-forming unit (CFU) assay, and found that CD34+ cells in LYL1-transduced EBs could form multi-lineage blood colonies. Furthermore the number of blood colonies originated from CD34+CD45+ cells in LYL1-transduced EBs was almost the same as that from CD34+CD45+ cells derived from CM bone marrow. These results suggested that enforced expression of LYL1 in CM ESCs promoted the emergence of HSCs by EB formation in vitro. The LYL1 was originally identified as the factor of a chromosomal translocation, resulting in T cell acute lymphoblastic leukemia [Mellentin JD et al., 1989]. The Lyl1-deficient mice display the reduction of B cells and impaired long-term hematopoietic reconstitution capacity [Capron C et al., 2006]. And, transduction of Lyl1 in mouse bone marrow cells induced the increase of HSCs and lymphocytes in vitro and in vivo [Lukov GL et al., 2011]. Therefore we hypothesized that LYL1 may play essential roles in bone marrow reconstitution by HSCs differentiated from CM ESCs. To examine this, we transplanted CD34+ cells derived from LYL1-transduced CM ESCs into bone marrow of sublethally irradiated NOG mice, and found that about 7% of CD45+ cells derived from CM ESCs were detected in peripheral blood (PB) of recipient mice at 8 weeks after transplant (n=4). Although CM CD45+ cells disappeared at 12 weeks after transplant, CD34+ cells (about 3%) were still found in bone marrow at the same time point. Given that TAL1-transduced EBs derived from CM ESCs could not reconstitute bone marrow of irradiated mice at all, LYL1 rather than TAL1 might be a more appropriate transcription factor that can give rise to CD34+ HSCs having the enhanced capability of bone marrow reconstitution from CM ESCs. We are planning to do in vivo study to prove this hypothesis in CM. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Biological characteristics of stem cells from foetal, cord blood and extraembryonic tissues

2010 ◽  
Vol 7 (suppl_6) ◽  
Author(s):  
Hassan Abdulrazzak ◽  
Dafni Moschidou ◽  
Gemma Jones ◽  
Pascale V. Guillot
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cord Blood ◽  
Embryonic Stem ◽  
White Matter Damage ◽  
Differentiation Potential ◽  
Wide Range ◽  
Biological Aspects ◽  
Extraembryonic Tissues

Foetal stem cells (FSCs) can be isolated during gestation from many different tissues such as blood, liver and bone marrow as well as from a variety of extraembryonic tissues such as amniotic fluid and placenta. Strong evidence suggests that these cells differ on many biological aspects such as growth kinetics, morphology, immunophenotype, differentiation potential and engraftment capacity in vivo . Despite these differences, FSCs appear to be more primitive and have greater multi-potentiality than their adult counterparts. For example, foetal blood haemopoietic stem cells proliferate more rapidly than those found in cord blood or adult bone marrow. These features have led to FSCs being investigated for pre- and post-natal cell therapy and regenerative medicine applications. The cells have been used in pre-clinical studies to treat a wide range of diseases such as skeletal dysplasia, diaphragmatic hernia and respiratory failure, white matter damage, renal pathologies as well as cancers. Their intermediate state between adult and embryonic stem cells also makes them an ideal candidate for reprogramming to the pluripotent status.

scholarly journals Allogeneic human umbilical cord Wharton’s jelly stem cells increase several-fold the expansion of human cord blood CD34+ cells both in vitro and in vivo

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hao Daniel Lin ◽  
Chui-Yee Fong ◽  
Arijit Biswas ◽  
Ariff Bongso
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Bone Marrow ◽  
Cord Blood ◽  
Umbilical Cord ◽  
Ex Vivo ◽  
Human Umbilical Cord ◽  
Cell Numbers ◽  
Cd34 Cells

Abstract Background The transplantation of human umbilical cord blood (UCB) CD34+ cells has been successfully used to treat hematological disorders but one major limitation has been the low cell numbers available. Mesenchymal stem cells (MSCs) lying within the bone marrow in vivo behave like a scaffold on which CD34+ cells interact and proliferate. We therefore evaluated the use of allogeneic MSCs from the human UC Wharton’s jelly (hWJSCs) as stromal support for the ex vivo expansion of CD34+ cells. Methods We performed an in-depth evaluation of the primitiveness, migration, adhesion, maturation, mitochondrial behavior, and pathway mechanisms of this platform using conventional assays followed by the evaluation of engraftment potential of the expanded CD34+ cells in an in vivo murine model. Results We demonstrate that hWJSCs and its conditioned medium (hWJSC-CM) support the production of significantly high fold changes of CD34+, CD34+CD133+, CD34+CD90+, CD34+ALDH+, CD34+CD45+, and CD34+CD49f+ cells after 7 days of interaction when compared to controls. In the presence of hWJSCs or hWJSC-CM, the CD34+ cells produced significantly more primitive CFU-GEMM colonies, HoxB4, and HoxA9 gene expression and lower percentages of CD34+CXCR4+ cells. There were also significantly higher N-cadherin+ cell numbers and increased cell migration in transwell migration assays. The CD34+ cells expanded with hWJSCs had significantly lower mitochondrial mass, mitochondrial membrane potential, and oxidative stress. Green Mitotracker-tagged mitochondria from CD34+ cells were observed lying within red CellTracker-tagged hWJSCs under confocal microscopy indicating mitochondrial transfer via tunneling nanotubes. CD34+ cells expanded with hWJSCs and hWJSC-CM showed significantly reduced oxidative phosphorylation (ATP6VIH and NDUFA10) and increased glycolytic (HIF-1a and HK-1) pathway-related gene expression. CD34+ cells expanded with hWJSCs for 7 days showed significant greater CD45+ cell chimerism in the bone marrow of primary and secondary irradiated mice when transplanted intravenously. Conclusions In this report, we confirmed that allogeneic hWJSCs provide an attractive platform for the ex vivo expansion of high fold numbers of UCB CD34+ cells while keeping them primitive. Allogeneic hWJSCs are readily available in abundance from discarded UCs, can be easily frozen in cord blood banks, thawed, and then used as a platform for UCB-HSC expansion if numbers are inadequate.

High-level ectopic HOXB4 expression confers a profound in vivo competitive growth advantage on human cord blood CD34+ cells, but impairs lymphomyeloid differentiation

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1759-1768 ◽  
Author(s):  
Bernhard Schiedlmeier ◽  
Hannes Klump ◽  
Elke Will ◽  
Gökhan Arman-Kalcek ◽  
Zhixiong Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Therapeutic Window ◽  
Hematopoietic Stem ◽  
Expression Levels ◽  
Cd34 Cells ◽  
Cord Blood Cd34 ◽  
The Impact

Ectopic retroviral expression of homeobox B4 (HOXB4) causes an accelerated and enhanced regeneration of murine hematopoietic stem cells (HSCs) and is not known to compromise any program of lineage differentiation. However, HOXB4 expression levels for expansion of human stem cells have still to be established. To test the proposed hypothesis that HOXB4 could become a prime tool for in vivo expansion of genetically modified human HSCs, we retrovirally overexpressed HOXB4 in purified cord blood (CB) CD34+ cells together with green fluorescent protein (GFP) as a reporter protein, and evaluated the impact of ectopic HOXB4 expression on proliferation and differentiation in vitro and in vivo. When injected separately into nonobese diabetic–severe combined immunodeficient (NOD/SCID) mice or in competition with control vector–transduced cells, HOXB4-overexpressing cord blood CD34+ cells had a selective growth advantage in vivo, which resulted in a marked enhancement of the primitive CD34+ subpopulation (P = .01). However, high HOXB4 expression substantially impaired the myeloerythroid differentiation program, and this was reflected in a severe reduction of erythroid and myeloid progenitors in vitro (P < .03) and in vivo (P = .01). Furthermore, HOXB4 overexpression also significantly reduced B-cell output (P < .01). These results show for the first time unwanted side effects of ectopic HOXB4 expression and therefore underscore the need to carefully determine the therapeutic window of HOXB4 expression levels before initializing clinical trials.

scholarly journals Differential effects of recombinant thrombopoietin and bone marrow stromal-conditioned media on neonatal versus adult megakaryocytes

Blood ◽  
2006 ◽  
Vol 108 (10) ◽  
pp. 3360-3362 ◽  
Author(s):  
Karen M. Pastos ◽  
William B. Slayton ◽  
Lisa M. Rimsza ◽  
Linda Young ◽  
Martha C. Sola-Visner
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cord Blood ◽  
Umbilical Cord ◽  
Umbilical Cord Blood ◽  
Peripheral Blood ◽  
Conditioned Media ◽  
Valuable Source ◽  
Cd34 Cells ◽  
Adult Bone

Abstract Umbilical cord blood (CB) is a valuable source of stem cells for transplantation, but CB transplantations are frequently complicated by delayed platelet engraftment. The reasons underlying this are unclear. We hypothesized that CB- and peripheral-blood (PB)–derived megakaryocytes (MKs) respond differently to the adult hematopoietic microenvironment and to thrombopoietin (Tpo). To test this, we cultured CB- and PB-CD34+ cells in adult bone marrow stromal conditioned media (CM) or unconditioned media (UCM) with increasing concentrations of recombinant Tpo and compared the effects of these conditions on CB-versus PB-MKs. PB-MKs reached highest ploidy in response to UCM + 100 ng/mL rTpo, and the addition of CM inhibited their maturation. In contrast, CB-MKs reached highest ploidy in CM without rTpo, and high rTpo concentrations (> 0.1 ng/mL) inhibited their maturation. This is the first evidence that human neonatal and adult MKs have substantially different biologic responses to Tpo and potentially to other cytokines.

Human Embryonic Stem Cell (hESC)-Derived Hematopoietic Elements Are Capable of Engrafting Primary as well as Secondary Fetal Sheep Recipients.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2685-2685
Author(s):  
A. Daisy Narayan ◽  
Jessica L. Chase ◽  
Adel Ersek ◽  
James A. Thomson ◽  
Rachel L. Lewis ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Peripheral Blood ◽  
Fetal Sheep ◽  
Hematopoietic Stem ◽  
Blood Samples ◽  
Human Dna ◽  
Cd34 Cells ◽  
Hematopoietic Activity

Abstract We used transplantation into 10 and 20 pre-immune fetal sheep recipients (55–65 days-old, term: 145 days) to evaluate the in vivo potential of hematopoietic elements derived from hESC. The in utero human/sheep xenograft model has proven valuable in assessing the in vivo hematopoietic activity of stem cells from a variety of fetal and post-natal human sources. Five transplant groups were established. Non-differentiated hESC were injected in one group. In the second and third group, embroid bodies differentiated for 8 days were injected whole or CD34+ cells were selected for injection. In the fourth and fifth group, hESC were differentiated on S17 mouse stroma layer and injected whole or CD34+ cells were selected for injection. The animals were allowed to complete gestation and be born. Bone marrow and peripheral blood samples were taken periodically up to over 12 months after injection, and PCR and flowcytometry was used to determine the presence of human DNA/blood cells in these samples. A total of 30 animals were analyzed. One primary recipient that was positive for human hematopoietic activity was sacrificed and whole bone marrow cells were transplanted into a secondary recipient. We analyzed the secondary recipient at 9 months post-injection by PCR and found it to be positive for human DNA in its peripheral blood and bone marrow. This animal was further challenged with human GM-CSF and human hematopoietic activity was noted by flowcytometry analyses of bone marrow and peripheral blood samples. Further, CD34+ cells enriched from its bone marrow were cultured in methylcellulose and human colonies were identified by PCR. We therefore conclude that hESC are capable of generating hematopoietic cells that engraft in 1° sheep recipients. These cells also fulfill the criteria for long-term engrafting hematopoietic stem cells as demonstrated by engraftment and differentiation in the 20 recipient.

Role of Osteoclasts in Regulation of Human Hematopoietic Stem Cell Niche and Fate.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4253-4253
Author(s):  
Shmuel Yaccoby ◽  
Kenichiro Yata ◽  
Yun Ge ◽  
Bart Barlogie ◽  
Joshua Epstein ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cord Blood ◽  
Scid Mice ◽  
Common Mechanism ◽  
Hematopoietic Stem ◽  
Variable Expression ◽  
Cd34 Cells ◽  
Rabbit Bone

Abstract Recent studies indicate that osteoblasts play an important role in maintaining hematopoietic stem cells (HSCs) niche in the bone marrow microenvironment. The aim of study was to test the effect of osteoclasts on the fate of HSCs in a long term co-culture assay. To generate osteoclasts, peripheral blood mononuclear cells from mobilized donors were cultured for 6–10 days in αMEM media supplemented with 10% FCS, M-CSF and RANKL. After removal of non-adherent cells, the cultures contained 95% multinucleated osteoclasts and their precursors. These osteoclasts expressed TRAP and formed resorption pits on bone slices (Yaccoby et al., Cancer Res., 2004). CD34+ cells were purified from donor PBSCs and cord blood using immunomagnetic beads separation (&gt;95% purity). Adult and cord blood HSCs were co-cultured with osteoclasts for up to 3 and 10 months, respectively, in media lacking any cytokines. Because osteoclasts do not survive long without M-CSF and RANKL, the HSCs were transferred to fresh osteoclast cultures every 6–10 days. Unlike their tight adherence to stromal cells, HSCs did not adhere to the osteoclasts and were easily recovered from co-cultures by gentle pipetting. Following 1 to 3 weeks of co-culture, committed HSCs rapidly differentiated into various hematopoietic cell lineage, followed by phagocytosis of terminal differentiated hematopoietic cells by the osteoclasts. The remaining HSCs were highly viable (&gt;90% by trypan blue exclusion) and gradually lost their CD34 expression, so that the cultures contained subpopulations of HSCs expressing CD34−/lowCD38+ and CD34−/lowCD38−. Quantitive real time RT-PCR (qRT-PCR) revealed loss of expression of CD34 and reduced expression of CD45 by HSCs co-cultured with osteoclasts longer than 6 weeks. Variable expression of CD34 on HSCs was previously reported in murine but not human HSCs (Tajima et al., Blood, 2001). The co-cultured HSCs showed reduced capacity of generating in vitro hematopoietic colonies, and did not differentiate into osteoclasts upon stimulation with M-CSF and RANKL. We next tested the long term engraftment of these co-cultured HSCs in 2 animal models. In the first model, cord blood and adult HSCs from 2 donors recovered after &gt;6 weeks in co-culture were injected I.V. into irradiated NOD/SCID mice. In the second novel model, co-cultured cord blood and adult HSCs from 2 donors were injected directly into rabbit bones implanted subcutaneously in SCID mice (SCID-rab model), 6–8 weeks after rabbit bone implantation. After 2–4 months, 10%±3% human CD45-expressing cells were identified in the NOD/SCID mice femora and 8%±4% in the SCID-rab mice rabbit bone. Our study suggests that osteoclasts promote rapid differentiation of committed HSCs and induce conversion of CD34+ cells to CD34− stem cells with self renewal potential. Intriguingly, long term co-culture of primary CD138-selected myeloma plasma cells (n=16) with osteoclasts resulted in dedifferentiation of tumor cells from a mature CD45− phenotype to an immature, CD45-expressing cells, suggesting a common mechanism of osteoclast-induced HSC and myeloma cell plasticity. This indicates that osteoclasts are important bone marrow component regulating human HSC niche, plasticity and fate.

Human Embryonic Stem Cells Demonstrate That Mpl Expression Initially Appears on a Population of CD31+ Endothelial Cells with Hemogenic Potential.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3617-3617
Author(s):  
Tamihiro Kamata ◽  
Yuping Gong ◽  
Shaohui Wang ◽  
Andrew D. Leavitt
Keyword(s):  
Stem Cells ◽  
Endothelial Cells ◽  
Cell Population ◽  
Hematopoietic Cells ◽  
Embryonic Stem ◽  
Adherent Cells ◽  
Hematopoietic Development ◽  
Cd34 Cells ◽  
Early Human

Abstract Mammalian hematopoiesis occurs adjacent to endothelial cells in the yolk sac and in the AGM region during fetal development, and in vivo cell labeling with Ac-LDL in fetal birds and mice indicates that hematopoietic cells can arise from endothelial cells. Blood forming potential has also been reported in endothelial cells isolated from human fetal liver and fetal bone marrow. However, the role of endothelial cells in the generation of hematopoietic cells remains poorly understood. While thrombopoietin (TPO) and its receptor, Mpl, are known for their critical role in megakaryocytopoiesis, Mpl−/ − mice and patients with congenital amegakaryocytic thrombocytopenia demonstrate that Mpl signaling is also important for the establishment and/or maintenance of hematopoietic stem cells. However, the nature of that role and the relevant Mpl-expressing cells remain unknown. To determine if Mpl signaling in early hematopoiesis involves hemogenic endothelium, we used human embryonic stem cells (hESCs) co-cultured with OP9 stromal cells, a robust model system for generating human hematopoietic cells. We found that CD34+ cells appeared by day 3–4 of co-culture, followed one day later by the appearance of CD31+ cells, nearly all of which appeared within the CD34+ population. The CD34+ cells increased to 20–40% of the total cell population by day 10, with nearly half co-expressing CD31+. Mpl+ cells first appeared on day 6–7, almost exclusively within the CD31+ population, increasing to 5–10% of total cells by day 10. The hESC:OP9 system generated a vascular-like network lined with von Willebrand Factor-expressing cells, which combined with FACS data showing the onset of Mpl expression on CD31+ cells, suggested that Mpl may first be expressed on vascular lining cells. Interestingly, Mpl expression precedes the detection of CD45+ cells, which are first observed on day 8–9. Moreover, round CD45+ cells appeared within the vascular networks, raising the possibility that vascular lining cells may give rise to hematopoietic cells. To begin to characterize the role of TPO/Mpl signaling in the CD31+ cell population, FACS-sorted CD31+ cells from day-9 and day-10 cultures were plated onto a fibronectin (FN)-coated surface, and non-adherent cells were removed after 1 hour. The adherent CD31+ cells uptake Ac-LDL and express vWF, characteristic of endothelial cells. When cultured in media supplemented with endothelial growth factors, including VEGF, EGF, bFGF, IGF-1, and heparin, the FN-adherent cells generated areas of cobblestone-like cell clusters and CD45+/CD34+ cells. When cultured in the same conditions plus TPO, the number of cobblestone-like clusters increased, and the number of CD45+/CD34+ hematopoietic cells generated increased 3–4 fold. Our data demonstrate that Mpl is expressed on a CD31+, vWF-expressing cell population with hemogenic potential, and that TPO/Mpl signaling increases the yield of hematopoietic cells generated from these cells. Ongoing sorting experiments, including the isolation and characterization of CD31+/Mpl+ cells, will further our understanding of where and how Mpl signaling affects early human hematopoietic development. HESCs provide a novel system for defining the role of TPO/Mpl signaling in early human hematopoietic development, which may lead to improved treatment of hematopoietic disorders.

Engraftment of Human Mesenchymal Stem Cells upon Transplantation into Newborn Rag2−/−gc−/− Mice.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1652-1652
Author(s):  
Patrick Ziegler ◽  
Steffen Boettcher ◽  
Hildegard Keppeler ◽  
Bettina Kirchner ◽  
Markus G. Manz
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Cord Blood ◽  
Human Mesenchymal Stem Cells ◽  
Rt Pcr ◽  
Hematopoietic Stem ◽  
Gm Csf ◽  
Cd34 Cells ◽  
Gene Transcripts

Abstract We recently demonstrated human T cell, B cell, dendritic cell, and natural interferon producing cell development and consecutive formation of primary and secondary lymphoid organs in Rag2−/−gc−/− mice, transplanted as newborns intra-hepatically (i.h.) with human CD34+ cord blood cells (Traggiai et al., Science 2004). Although these mice support high levels of human cell engraftment and continuous T and B cell formation as well as CD34+ cell maintenance in bone marrow over at least six month, the frequency of secondary recipient reconstituting human hematopoietic stem and progenitor cells within the CD34+ pool declines over time. Also, although some human immune responses are detectable upon vaccination with tetanus toxoid, or infection with human lymphotropic viruses such as EBV and HIV, these responses are somewhat weak compared to primary human responses, and are inconsistent in frequency. Thus, some factors sustaining human hematopoietic stem cells in bone marrow and immune responses in lymphoid tissues are either missing in the mouse environment, or are not cross-reactive on human cells. Human mesenchymal stem cells (MSCs) replicate as undifferentiated cells and are capable to differentiate to multiple mesenchymal tissues such as bone, cartilage, fat, muscle, tendon, as well as marrow and lymphoid organ stroma cells, at least in vitro (e.g. Pittenger et al., Science 1999). Moreover, it was shown that MSCs maintain CD34+ cells to some extend in vitro, and engraft at low frequency upon transplantation into adult immunodeficient mice or fetal sheep as detected by gene transcripts. We thus postulated that co-transplantation of cord blood CD34+ cells and MSCs into newborn mice might lead to engraftment of both cell types, and to provision of factors supporting CD34+ maintenance and immune system function. MSCs were isolated and expanded by plastic adherence in IMDM, supplemented with FCS and cortisone (first 3 weeks) from adult bone marrow, cord blood, and umbilical vein. To test their potential to support hemato-lymphopoiesis, MSCs were analyzed for human hemato-lymphotropic cytokine transcription and production by RT-PCR and ELISA, respectively. MSCs from all sources expressed gene-transcripts for IL-6, IL-7, IL-11, IL-15, SCF, TPO, FLT3L, M-CSF, GM-CSF, LIF, and SDF-1. Consistently, respective cytokines were detected in supernatants at the following, declining levels (pg/ml): IL-6 (10000-10E6) > SDF-1 > IL-11 > M-CSF > IL-7 > LIF > SCF > GM-CSF (0–450), while FLT3L and TPO were not detectable by ELISA. Upon i.h. transplantation of same passage MSCs (1X10E6) into sublethally irradiated (2x2 Gy) newborn Rag2−/−gc−/− mice, 2-week engraftment was demonstrated by species specific b2m-RT-PCR in thymus, spleen, lung, liver and heart in n=7 and additionally in thymus in n=3 out of 13 animals analyzed. Equally, GFP-RNA transcripts were detectable in the thymus for up to 6 weeks, the longest time followed, upon co-transplantation of same source CD34+ cells and retrovirally GFP-transduced MSCs in n=2 out of 4 animals. Further engraftment analysis of ongoing experiments will be presented. Overall, these results demonstrate that human MSC produce hemato-lymphoid cytokines and engraft in newborn transplanted Rag2−/−gc−/− mice, at least at early time-points analyzed. This model thus might allow studying hematopoietic cell and MSC-derived cell interaction, and might serve as a testing system for MSC delivered gene therapy in vivo.

Humanized Sc(Fv)2 Minibody against C-Mpl Successfully Increased Platelet Number in Monkey and Increased Engraftment of Human Umbilical Cord Blood Cells in NOD/SCID Mouse.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2322-2322
Author(s):  
Takashi Yoshikubo ◽  
Yoshihiro Matsumoto ◽  
Masahiko Nanami ◽  
Takayuki Sakurai ◽  
Hiroyuki Tsunoda ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Cord Blood ◽  
Progenitor Cells ◽  
Umbilical Cord ◽  
Umbilical Cord Blood ◽  
Platelet Recovery ◽  
Cynomolgus Monkeys ◽  
Cd34 Cells

Abstract Thrombopoietin (TPO, the ligand for c-mpl) is a key factor for megakaryopoiesis. Several clinical trials of TPO have been conducted for thrombocytopenia without much success due to, in part, the production of neutralized antibodies against endogenous TPO, which causes thrombocytopenia. To overcome this problem, we previously demonstrated that mouse type minibody against c-mpl, with an amino acid sequence totally different from TPO, showed megakaryopoiesis and increased platelet numbers in monkey. This time, using CDR grafting, we generated a humanized sc(Fv)2VB22B minibody (huVB22B) against c-mpl for therapeutic use. The new minibody showed almost the same activity in vitro as TPO and the mouse type minibody, confirmed by both a human megakaryocyte cell (CD41+) differentiation assay and a proliferation assay with TPO-dependent cell line, M-07e. Single sc or iv administration of huVB22B to cynomolgus monkeys showed a dose-dependent increase in platelet numbers. Pharmacokinetic analysis showed that the plasma half-life (T1/2) of huVB22B at iv and sc administration to cynomolgus monkeys was 7–8 h and 11–16 h, respectively. After administration of huVB22B, the platelets of these monkeys increased and showed functional aggregation in response to ADP in vitro. Repeated administration of huVB22B (0.2, 2 and 20mg/kg/week) revealed that the increase in platelet level in cynomolgus monkeys was maintained for a month. Very slight reticular fibers in bone marrow were detected in a high dose group (20mg/ kg). No overt changes were detected by toxicity evaluations including clinical pathology and histopathology in 0.2 and 2mg/kg groups. No neutralized activities in plasma were observed during these experiments. Next, we examined the activities of huVB22B on human bone marrow-derived CD34-positive cells (BM-CD34+) and umbilical cord blood-derived CD34-positive cells (UCB-CD34+) in vitro. BM-CD34+ and UCB-CD34+ cells were cultured with huVB22B in serum free medium. HuVB22B induced differentiation of CD41+ cells from BM-CD34+ or UCB-CD34+ cells in a similar dose-dependent manner. However, UCB-CD34+ cells showed greater proliferation in response to huVB22B compared to BM-CD34+ cells. We then examined the in vivo activities of huVB22B on UCB CD34+ cells by treating NOD/SCID mice transplanted with human UCB-CD34+ cells with huVB22B and examining the bone marrow cells of the mice. The results showed that, compared with the control, administration of huVB22B showed an increase in the number of human hematopoietic progenitor cells (CD34+), lymphoid lineage cells (CD19+), and myeloid lineage cells (CD33+) in addition to human CFU-Meg cells (CD41+). These results suggest that c-mpl stimulation in vivo after transplantation might increase engraftment of progenitor cells in the bone marrow microenvironment and subsequently induce differentiation to multilineage cells. Umbilical cord blood transplantation faces frequent complications including a low-level stem/progenitor cell engraftment and delayed platelet recovery. Our results suggest that c-mpl stimulation might be used to increase the engraftment of UCB stem/progenitor cells and shorten the time of platelet recovery following UCB transplantation.

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