Emp Null Mice Are Non-Viable and Exhibit Erythroid Differentiation Defect.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 806-806 ◽  
Author(s):  
Shivani Soni ◽  
Shashi Bala ◽  
Babette Gwynn ◽  
Kenneth E. Sahr ◽  
Luanne L. Peters ◽  
...  
Keyword(s):  
Fetal Liver ◽  
Direct Sequencing ◽  
Embryonic Stem ◽  
Gene Trap ◽  
Physical Contact ◽  
Erythroid Cells ◽  
Wild Type ◽  
Definitive Erythropoiesis

Abstract Emp, erythroblast macrophage protein, was originally detected in erythroblasts and macrophages, which form erythroblastic islands during erythropoiesis in the human bone marrow. The physical contact between erythroblasts and macrophages was suggested to promote the terminal maturation of erythroblasts, leading to their enucleation in vitro. To evaluate the function of Emp in vivo, we employed gene targeting studies to develop an Emp(−/−) mouse model. Mouse embryonic stem cells containing a gene-trap insertion in Emp were obtained from BayGenomics. Insertion of the gene-trap vector into Emp was verified by direct sequencing of cDNA obtained by 5′RACE. Chimeric mice generated by blastocyst microinjection were intercrossed, and the offspring were genotyped by PCR and Southern hybridization. The Emp (+/−) mice were healthy and fertile. However, no live Emp (−/−) mice were found among the progeny of the Emp (+/−) intercrosses. Analysis of timed pregnancies revealed that Emp (−/−) embryos were present at a frequency roughly consistent with Mendelian inheritance throughout the embryonal stages. Homozygous Emp (−/−) embryos were small and pale compared to their littermates, and they survived embryonic development but died at birth. To determine the effect, if any, of Emp gene deletion on definitive hematopoiesis, livers of +/+, +/−, and −/− embryos at E15.5 were examined after H&E and Giemsa staining of paraffin-embedded serial sections, and cytospins. We found few mature erythroid cells in the sinusoids of homozygotes, in contrast to those of either wild-type or heterozygotes, where abundant enucleated red blood cells were observed. Although nucleated erythrocytes were found in both wild-type and mutant embryos, their relative proportions were very different: the less mature forms (proerythroblasts) predominated in the −/− embryos whereas the more mature forms (polychromatophilic/orthochromatic and enucleated erythrocytes) were most common in +/+ and +/− embryos. Furthermore, erythroblastic islands consisting of a central macrophage surrounded by developing erythroblasts were seen in the cytospin preparations of wild-type and heterozygote livers but not in those of homozygous null livers. Since fetal liver macrophages (FLMs) are indispensable for definitive erythropoiesis, we investigated the effect that Emp’s absence might have on development of FLMs. The E15.5 fetal liver sections were stained with the macrophage-specific F4/80 antigen. Numerous F4/80-positive macrophages were present throughout the liver of normal embryos whereas, the number was substantially reduced in Emp (−/−) liver. In summary, in the absence of Emp, FLMs are significantly reduced and terminal maturation of erythroid cells is negatively affected. Thus, the availability of Emp(−/−) embryos will provide a unique experimental model to study the function of macrophages in definitive erythropoiesis.

scholarly journals Lineage-specific combinatorial action of enhancers regulates mouse erythroid Gata1 expression

Blood ◽  
2010 ◽  
Vol 115 (17) ◽  
pp. 3463-3471 ◽  
Author(s):  
Roy Drissen ◽  
Boris Guyot ◽  
Lin Zhang ◽  
Ann Atzberger ◽  
Jackie Sloane-Stanley ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Erythroid Differentiation ◽  
Cell Types ◽  
Physical Contact ◽  
Erythroid Cells ◽  
Additional Element ◽  
Enhancer Element ◽  
Activating Transcription Factor ◽  
Definitive Erythropoiesis

Abstract Precise spatiotemporal control of Gata1 expression is required in both early hematopoietic progenitors to determine erythroid/megakaryocyte versus granulocyte/monocyte lineage output and in the subsequent differentiation of erythroid cells and megakaryocytes. An enhancer element upstream of the mouse Gata1 IE (1st exon erythroid) promoter, mHS−3.5, can direct both erythroid and megakaryocytic expression. However, loss of this element ablates only megakaryocytes, implying that an additional element has erythroid specificity. Here, we identify a double DNaseI hypersensitive site, mHS−25/6, as having erythroid but not megakaryocytic activity in primary cells. It binds an activating transcription factor complex in erythroid cells where it also makes physical contact with the Gata1 promoter. Deletion of mHS−25/6 or mHS−3.5 in embryonic stem cells has only a modest effect on in vitro erythroid differentiation, whereas loss of both elements ablates both primitive and definitive erythropoiesis with an almost complete loss of Gata1 expression. Surprisingly, Gata2 expression was also concomitantly low, suggesting a more complex interaction between these 2 factors than currently envisaged. Thus, whereas mHS−3.5 alone is sufficient for megakaryocytic development, mHS−3.5 and mHS−25/6 collectively regulate erythroid Gata1 expression, demonstrating lineage-specific differences in Gata1 cis-element use important for development of these 2 cell types.

Brachyury - a gene affecting mouse gastrulation and early organogenesis

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 157-165 ◽  
Author(s):  
R. S. P. Beddington ◽  
P. Rashbass ◽  
V. Wilson
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Coat Colour ◽  
Es Cell ◽  
Wild Type ◽  
Mesoderm Cell ◽  
Rostrocaudal Axis

Mouse embryos that are homozygous for the Brachyury (T) deletion die at mid-gestation. They have prominent defects in the notochord, the allantois and the primitive streak. Expression of the T gene commences at the onset of gastrulation and is restricted to the primitive streak, mesoderm emerging from the streak, the head process and the notochord. Genetic evidence has suggested that there may be an increasing demand for T gene function along the rostrocaudal axis. Experiments reported here indicate that this may not be the case. Instead, the gradient in severity of the T defect may be caused by defective mesoderm cell movements, which result in a progressive accumulation of mesoderm cells near the primitive streak. Embryonic stem (ES) cells which are homozygous for the T deletion have been isolated and their differentiation in vitro and in vivo compared with that of heterozygous and wild-type ES cell lines. In +/+ ↔ T/T ES cell chimeras the Brachyury phenotype is not rescued by the presence of wild-type cells and high level chimeras show most of the features characteristic of intact T/T mutants. A few offspring from blastocysts injected with T/T ES cells have been born, several of which had greatly reduced or abnormal tails. However, little or no ES cell contribution was detectable in these animals, either as coat colour pigmentation or by isozyme analysis. Inspection of potential +/+ ↔ T/T ES cell chimeras on the 11th or 12th day of gestation, stages later than that at which intact T/T mutants die, revealed the presence of chimeras with caudal defects. These chimeras displayed a gradient of ES cell colonisation along the rostrocaudal axis with increased colonisation of caudal regions. In addition, the extent of chimerism in ectodermal tissues (which do not invaginate during gastrulation) tended to be higher than that in mesodermal tissues (which are derived from cells invaginating through the primitive streak). These results suggest that nascent mesoderm cells lacking the T gene are compromised in their ability to move away from the primitive streak. This indicates that one function of the T genemay be to regulate cell adhesion or cell motility properties in mesoderm cells. Wild-type cells in +/+ ↔ T/T chimeras appear to move normally to populate trunk and head mesoderm, suggesting that the reduced motility in T/T cells is a cell autonomous defect

scholarly journals Hypoxic stress underlies defects in erythroblast islands in the Rb-null mouse

Blood ◽  
2007 ◽  
Vol 110 (6) ◽  
pp. 2173-2181 ◽  
Author(s):  
Benjamin T. Spike ◽  
Benjamin C. Dibling ◽  
Kay F. Macleod
Keyword(s):  
Fetal Liver ◽  
Cell Maturation ◽  
Null Mouse ◽  
Hypoxic Stress ◽  
Red Cell ◽  
Exogenous Stress ◽  
Erythroid Maturation ◽  
Definitive Erythropoiesis

Abstract Definitive erythropoiesis occurs in islands composed of a central macrophage in contact with differentiating erythroblasts. Erythroid maturation including enucleation can also occur in the absence of macrophages both in vivo and in vitro. We reported previously that loss of Rb induces cell-autonomous defects in red cell maturation under stress conditions, while other reports have suggested that the failure of Rb-null erythroblasts to enucleate is due to defects in associated macrophages. Here we show that erythropoietic islands are disrupted by hypoxic stress, such as occurs in the Rb-null fetal liver, that Rb−/− macrophages are competent for erythropoietic island formation in the absence of exogenous stress and that enucleation defects persist in Rb-null erythroblasts irrespective of macrophage function.

scholarly journals Pattern of pyruvate kinase isozymes in erythroleukemia cell lines and in normal human erythroblasts

Blood ◽  
1984 ◽  
Vol 64 (4) ◽  
pp. 930-936 ◽  
Author(s):  
I Max-Audit ◽  
U Testa ◽  
D Kechemir ◽  
M Titeux ◽  
W Vainchenker ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Cell Lines ◽  
Fetal Liver ◽  
Erythroid Cells ◽  
Low Concentrations ◽  
Erythroleukemia Cell ◽  
Erythroleukemic Cell ◽  
High Level

To further investigate the erythroid nature of the two human erythroleukemia cell lines, K562 and HEL-60, and to define the ontogeny of pyruvate kinase (PK) isozymes (R, M2) in developing human erythroid cells, we have studied the isozymic alterations, if any, during differentiation of these cell lines in vitro and normoblasts isolated from fetal liver in vivo. PK activity of erythroleukemic cell lines was intermediate between that observed in leukocytes and in fetal liver erythroblasts. These cell lines contained a high level of M2-PK, but R- PK was always present, albeit at low concentrations, in all the clones or subclones we studied. Erythroblasts from fetal liver were separated according to density on a Stractan gradient. R-PK levels were nearly constant in the different fractions, whereas M2-PK levels markedly decreased as the erythroblasts became mature and almost completely disappeared in late erythroid cells. Thus, these results clearly demonstrate the erythroid origin of these cell lines.

scholarly journals Pattern of pyruvate kinase isozymes in erythroleukemia cell lines and in normal human erythroblasts

Blood ◽  
1984 ◽  
Vol 64 (4) ◽  
pp. 930-936 ◽  
Author(s):  
I Max-Audit ◽  
U Testa ◽  
D Kechemir ◽  
M Titeux ◽  
W Vainchenker ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Cell Lines ◽  
Fetal Liver ◽  
Erythroid Cells ◽  
Low Concentrations ◽  
Erythroleukemia Cell ◽  
Erythroleukemic Cell ◽  
High Level

Abstract To further investigate the erythroid nature of the two human erythroleukemia cell lines, K562 and HEL-60, and to define the ontogeny of pyruvate kinase (PK) isozymes (R, M2) in developing human erythroid cells, we have studied the isozymic alterations, if any, during differentiation of these cell lines in vitro and normoblasts isolated from fetal liver in vivo. PK activity of erythroleukemic cell lines was intermediate between that observed in leukocytes and in fetal liver erythroblasts. These cell lines contained a high level of M2-PK, but R- PK was always present, albeit at low concentrations, in all the clones or subclones we studied. Erythroblasts from fetal liver were separated according to density on a Stractan gradient. R-PK levels were nearly constant in the different fractions, whereas M2-PK levels markedly decreased as the erythroblasts became mature and almost completely disappeared in late erythroid cells. Thus, these results clearly demonstrate the erythroid origin of these cell lines.

Expression Trapping: Identification of Novel Genes Expressed in Hematopoietic and Endothelial Lineages by Gene Trapping in ES Cells

Blood ◽  
1998 ◽  
Vol 92 (12) ◽  
pp. 4622-4631 ◽  
Author(s):  
William L. Stanford ◽  
Georgina Caruana ◽  
Katherine A. Vallis ◽  
Maneesha Inamdar ◽  
Michihiro Hidaka ◽  
...  
Keyword(s):  
Large Scale ◽  
Es Cells ◽  
Expression Patterns ◽  
Embryonic Stem ◽  
Gene Trap ◽  
Novel Genes ◽  
Specific Expression ◽  
Blood Island

Abstract We have developed a large-scale, expression-based gene trap strategy to perform genome-wide functional analysis of the murine hematopoietic and vascular systems. Using two different gene trap vectors, we have isolated embryonic stem (ES) cell clones containing lacZreporter gene insertions in genes expressed in blood island and vascular cells, muscle, stromal cells, and unknown cell types. Of 79 clones demonstrating specific expression patterns, 49% and 16% were preferentially expressed in blood islands and/or the vasculature, respectively. The majority of ES clones that expressedlacZ in blood islands also expressed lacZ upon differentiation into hematopoietic cells on OP9 stromal layers. Importantly, the in vivo expression of the lacZ fusion products accurately recapitulated the observed in vitro expression patterns. Expression and sequence analysis of representative clones suggest that this approach will be useful for identifying and mutating novel genes expressed in the developing hematopoietic and vascular systems.

GATA-1 Regulates Growth and Differentiation of Definitive Erythroid Lineage Cells During In Vitro ES Cell Differentiation

Blood ◽  
1998 ◽  
Vol 92 (11) ◽  
pp. 4108-4118 ◽  
Author(s):  
Naruyoshi Suwabe ◽  
Satoru Takahashi ◽  
Toru Nakano ◽  
Masayuki Yamamoto
Keyword(s):  
Es Cells ◽  
Embryonic Stem ◽  
Erythroid Cells ◽  
Es Cell ◽  
Globin Mrna ◽  
Differentiated Cells ◽  
Vitro Analysis ◽  
Definitive Hematopoiesis

Abstract Although the importance of GATA-1 in both primitive and definitive hematopoietic lineages has been shown in vivo, the precise roles played by GATA-1 during definitive hematopoiesis have not yet been clarified. In vitro differentiation of embryonic stem (ES) cells using OP9 stroma cells can generate primitive and definitive hematopoietic cells separately, and we have introduced a method that separates hematopoietic progenitors and differentiated cells produced in this system. Closer examination showed that the expression of erythroid transcription factors in this system is regulated in a differentiation stage-specific manner. Therefore, we examined differentiation of GATA-1 promoter-disrupted (GATA-1.05) ES cells using this system. Because the GATA-1.05 mice die by 12.5 embryonic days due to the lack of primitive hematopoiesis, the in vitro analysis is an important approach to elucidate the roles of GATA-1 in definitive hematopoiesis. Consistent with the in vivo observation, differentiation of GATA-1.05 mutant ES cells along both primitive and definitive lineages was arrested in this ES cell culture system. Although the maturation-arrested primitive lineage cells did not express detectable amounts of ɛy-globin mRNA, the blastlike cells accumulated in the definitive stage showed β-globin mRNA expression at approximately 70% of the wild type. Importantly, the TER119 antigen was expressed and porphyrin was accumulated in the definitive cells, although the levels of both were reduced to approximately 10%, indicating that maturation of definitive erythroid cells is arrested by the lack of GATA-1 with different timing from that of the primitive erythroid cells. We also found that the hematopoietic progenitor fraction of GATA-1.05 cells contains more colony-forming activity, termed CFU-OP9. These results suggest that theGATA-1.05 mutation resulted in proliferation of proerythroblasts in the definitive lineage.

The Rho Family GTPase Cdc42 Regulates Multiple Hematopoietic Stem/Progenitor Cell Functions and Erythropoiesis.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 32-32
Author(s):  
Lei Wang ◽  
Linda Yang ◽  
Marie–Dominique Filippi ◽  
David A. Williams ◽  
Yi Zheng
Keyword(s):  
Bone Marrow ◽  
Fetal Liver ◽  
Brdu Incorporation ◽  
Low Density ◽  
Actin Assembly ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Rho Family

Abstract The Rho family GTPase Cdc42 has emerged as a key signal transducer in cell regulation. To investigate its physiologic function in hematopoiesis, we have generated mice carrying a gene targeted null allele of cdc42gap, a major negative regulatory gene of Cdc42 and mice with conditional targeted cdc42 allele (cdc42flox/flox). Deletion of the respective gene products in mice was confirmed by PCR genotyping and Western blotting. Low-density fetal liver or bone marrow cells from Cdc42GAP−/− mice displayed ~3 fold elevated Cdc42 activity and normal RhoA, Rac1 or Rac2 activity, indicating that cdc42gap deletion has a specific effect on Cdc42 activity. The Cdc42GAP-deficient hematopoietic stem/progenitor cells (HSC/Ps, Lin−c-Kit+) generated from Cdc42GAP−/− E14.5 fetal liver and the Cdc42−/− HSC/Ps derived by in vitro expression of Cre via a retrovirus vector from Cdc42flox/flox low density bone marrow showed a growth defect in liquid culture that was associated with increased apoptosis but normal cell cycle progression. Cdc42GAP-deficient HSC/Ps displayed impaired cortical F-actin assembly with extended actin protrusions upon exposure to SDF–1 in vitro and a punctuated actin structure after SCF stimulation while Cdc42−/− but not wild type HSC/Ps responded to SDF-1 in inducing membrane protrusions. Both Cdc42−/− and Cdc42GAP−/− HSC/Ps were markedly decreased in adhesion to fibronectin. Moreover, both Cdc42−/− and Cdc42GAP−/− HSC/Ps showed impaired migration in response to SDF-1. These results demonstrate that Cdc42 regulation is essential for multiple HSC/P functions. To understand the in vivo hematopoietic function of Cdc42, we have characterized the Cdc42GAP−/− mice further. The embryos and newborns of homozygous showed a ~30% reduction in hematopoietic organ (i.e. liver, bone marrow, thymus and spleen) cellularity, consistent with the reduced sizes of the animals. This was attributed to the increased spontaneous apoptosis associated with elevated Cdc42/JNK/Bid activities but not to a proliferative defect as revealed by in vivo TUNEL and BrdU incorporation assays. ~80% of Cdc42GAP−/− mice died one week after birth, and the surviving pups attained adulthood but were anemic. Whereas Cdc42GAP−/− mice contained small reduction in the frequency of HSC markers and normal CFU-G, CFU-M, and CFU-GM activities, the frequency of BFU-E and CFU-E were significantly reduced. These results suggest an important role of Cdc42 in erythropoiesis in vivo. Taken together, we propose that Cdc42 is essential for multiple HSC/P functions including survival, actin cytoskeleton regulation, adhesion and migration, and that deregulation of its activity can have a significant impact on erythropoiesis. Cdc42 regulates HSC/P functions and erythropoiesis Genotype/phenotype Apoptosis increase Adhesion decrease Migration decrease F-actin assembly HSC frequency decrease BFU-E, CFU-E decrease The numbers were indicated as fold difference compared with wild type. ND:not determined yet. Cdc42GAP−/− 2.43, p<0.005 0.97, p<0.01 1.01, p<0.01 protrusion (SDF-1); punctruated (SCF) 0.34, p<0.05 0.92, p<0.01; 0.38, p<0 Cdc42−/− 3.68, p<0.005 0.98, p<0.001 3.85, p<0.005 protrusion (SDF-1) ND ND

GA Binding Protein (GABP) Is Required for Development and Maturation of Myeloid Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 776-776
Author(s):  
Zhongfa Yang ◽  
Alan G. Rosmarin
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Target Genes ◽  
Embryonic Stem ◽  
Myeloid Cells ◽  
Transactivation Domain ◽  
Wild Type ◽  
Floxed Allele

Abstract GABP is an ets transcription factor that regulates transcription of key myeloid genes, including CD18 (beta2 leukocyte integrin), neutrophil elastase, lysozyme, and other key mediators of the inflammatory response; it is also known to regulate important cell cycle control genes. GABP consists of two distinct and unrelated proteins that, together, form a functional transcription factor complex. GABPalpha (GABPa) is an ets protein that binds to DNA; it forms a tetrameric complex by recruiting its partner, GABPbeta (GABPb), which contains the transactivation domain. GABPa is a single copy gene in both the human and murine genomes and it is the only protein that can recruit GABPb to DNA. We cloned GABPa from a murine genomic BAC library and prepared a targeting vector in which exon 9 (which encodes the GABPa ets domain) was flanked by loxP (floxed) recombination sites. The targeting construct was electroporated into embryonic stem cells, homologous recombinants were implanted into pseudopregnant mice, heterozygous floxed GABPa mice were identified, and intercrossing yielded expected Mendelian ratios of wild type, heterozygous, and homozygous floxed GABPa mice. Breeding of heterozygous floxed GABPa mice to CMV-Cre mice (which express Cre recombinase in all tissues) yielded expected numbers of hemizygous mice (only one intact GABPa allele), but no nullizygous (GABPa−/−) mice among 64 pups; we conclude that homozygous deletion of GABPa causes an embryonic lethal defect. To determine the effect of GABPa deletion on myeloid cell development, we bred heterozygous and homozygous floxed mice to LysMCre mice, which express Cre only in myeloid cells. These mice had a normal complement of myeloid cells but, unexpectedly, PCR indicated that their Gr1+ myeloid cells retained an intact (undeleted) floxed GABPa allele. We detected similar numbers of in vitro myeloid colonies from bone marrow of wild type, heterozygous floxed, and homozygous floxed progeny of LysMCre matings. However, PCR of twenty individual in vitro colonies from homozygous floxed mice indicated that they all retained an intact floxed allele. Breeding of floxed GABPa/LysMCre mice with hemizygous mice indicated that retention of a floxed allele was not due to incomplete deletion by LysMCre; rather, it appears that only myeloid cells that retain an intact GABPa allele can survive to mature in vitro or in vivo. We prepared murine embryonic fibroblasts from homozygous floxed mice and efficiently deleted GABPa in vitro. We found striking abnormalities in proliferation and G1/S phase arrest. We used quantitative RT-PCR to identify mechanisms that account for the altered growth of GABPa null cells. We found dramatically reduced expression of known GABP target genes that regulate DNA synthesis and cell cycle that appear to account for the proliferative defect. We conclude that GABPa is required for growth and maturation of myeloid cells and we identified downstream targets that may account for their failure to proliferate and mature in vitro and in vivo.

Primitive and Definitive Erythropoiesis

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. SCI-37-SCI-37
Author(s):  
James Palis
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Yolk Sac ◽  
Erythroid Cells ◽  
Transient Wave ◽  
Self Renewal ◽  
Primitive Erythropoiesis ◽  
Definitive Erythropoiesis

Abstract Abstract SCI-37 Studies in mammalian and nonmammalian vertebrate embryos indicate that erythropoiesis comes in two flavors: primitive and definitive. The primitive erythroid lineage in mammalian embryos is characterized by a transient wave of lineage-committed progenitors that emerge from the yolk sac and generate a wave of precursors that synchronously mature in the bloodstream. Primitive erythroid precursors dynamically regulate embryonic globin gene expression and ultimately enucleate to form erythrocytes. Primitive erythropoiesis is superseded by definitive erythroid cells that mature extravascularly in association with macrophage cells. Studies in the mouse embryo indicate that definitive erythropoiesis has two distinct developmental origins. The first is a transient wave of erythro-myeloid progenitors (EMP) that emerge from the yolk sac and seed the early fetal liver. The second is a long-term program of erythropoiesis derived from hematopoietic stem cells. Erythropoietin is the central regulator of definitive erythropoiesis, in part by regulating the survival of committed progenitors. In contrast, the role of erythropoietin in primitive erythropoiesis remains poorly understood. Recent studies indicate that erythropoietin does not regulate the primitive erythroid progenitor compartment, but rather plays a critical role in establishing an antiapoptotic state during the terminal maturation of primitive erythroblasts. EMP-derived proerythroblasts are capable of extensive self-renewal in vitro, while primitive erythroid progenitors are incapable of self-renewal under the same conditions. These studies, taken together, indicate that the primitive and definitive forms of erythropoiesis have fundamental differences in the regulation of red cell output. The overlapping emergence of primitive and definitive erythroid lineages in differentiating embryonic stem cells suggests that the transient yolk-sac-derived primitive and EMP-derived definitive erythroid programs are recapitulated in vitro. These studies offer the hope that human embryonic stem cells can serve as a source of functional definitive erythroid cells for transfusion therapy. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document