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Gelon L, Fromont L, Lefrançais E. Occurrence and role of lung megakaryocytes in infection and inflammation. Front Immunol 2022; 13:1029223. [PMID: 36524131 PMCID: PMC9745136 DOI: 10.3389/fimmu.2022.1029223] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 11/09/2022] [Indexed: 12/03/2022] Open
Abstract
Megakaryocytes (MKs) are large cells giving rise to platelets. It is well established that in adults, MKs develop from hematopoietic stem cells and reside in the bone marrow. MKs are also rare but normal constituents of the venous blood returning to the lungs, and MKs are found in the lung vasculature (MKcirc), suggesting that these cells are migrants from the bone marrow and get trapped in lung capillaries where the final steps of platelet production can occur. An unprecedented increase in the number of lung and circulating MKs was described in coronavirus disease 2019 (COVID-19) patients, suggesting that lung thrombopoiesis may be increased during lung infection and/or thromboinflammation. In addition to the population of platelet-producing intravascular MKs in the lung, a population of lung-resident megakaryocytes (MKL) has been identified and presents a specific immune signature compared to its bone marrow counterparts. Recent single-cell analysis and intravital imaging have helped us gain a better understanding of these populations in mouse and human. This review aims at summarizing the recent data on increased occurrence of lung MKs and discusses their origin, specificities, and potential role in homeostasis and inflammatory and infectious lung diseases. Here, we address remaining questions, controversies, and methodologic challenges for further studies of both MKcirc and MKL.
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Davenport P, Liu ZJ, Sola-Visner M. Fetal vs adult megakaryopoiesis. Blood 2022; 139:3233-3244. [PMID: 35108353 PMCID: PMC9164738 DOI: 10.1182/blood.2020009301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/12/2022] [Indexed: 11/20/2022] Open
Abstract
Fetal and neonatal megakaryocyte progenitors are hyperproliferative compared with adult progenitors and generate a large number of small, low-ploidy megakaryocytes. Historically, these developmental differences have been interpreted as "immaturity." However, more recent studies have demonstrated that the small, low-ploidy fetal and neonatal megakaryocytes have all the characteristics of adult polyploid megakaryocytes, including the presence of granules, a well-developed demarcation membrane system, and proplatelet formation. Thus, rather than immaturity, the features of fetal and neonatal megakaryopoiesis reflect a developmentally unique uncoupling of proliferation, polyploidization, and cytoplasmic maturation, which allows fetuses and neonates to populate their rapidly expanding bone marrow and blood volume. At the molecular level, the features of fetal and neonatal megakaryopoiesis are the result of a complex interplay of developmentally regulated pathways and environmental signals from the different hematopoietic niches. Over the past few years, studies have challenged traditional paradigms about the origin of the megakaryocyte lineage in both fetal and adult life, and the application of single-cell RNA sequencing has led to a better characterization of embryonic, fetal, and adult megakaryocytes. In particular, a growing body of data suggests that at all stages of development, the various functions of megakaryocytes are not fulfilled by the megakaryocyte population as a whole, but rather by distinct megakaryocyte subpopulations with dedicated roles. Finally, recent studies have provided novel insights into the mechanisms underlying developmental disorders of megakaryopoiesis, which either uniquely affect fetuses and neonates or have different clinical presentations in neonatal compared with adult life.
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Affiliation(s)
- Patricia Davenport
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA; and
- Harvard Medical School, Boston, MA
| | - Zhi-Jian Liu
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA; and
- Harvard Medical School, Boston, MA
| | - Martha Sola-Visner
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA; and
- Harvard Medical School, Boston, MA
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3
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Bertović I, Bura A, Jurak Begonja A. Developmental differences of in vitro cultured murine bone marrow- and fetal liver-derived megakaryocytes. Platelets 2021; 33:887-899. [PMID: 34915807 DOI: 10.1080/09537104.2021.2007869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Multiple lines of evidence support differences in the megakaryopoiesis during development. Murine in vitro models to study megakaryopoiesis employ cultured megakaryocytes MKs derived from adult bone marrow (BM) or fetal livers (FL) of mouse embryos. Mouse models allow to study the molecular basis for cellular changes utilizing conditional or knock-out models and permit further in vitro genetic or pharmacological manipulations. Despite being extensively used, MKs cultured from these two sources have not been systematically compared. In the present study, we compared BM- and FL-derived MKs, assessing their size, proplatelet production capacity, expression of common MK markers (αIIb, β3, GPIb α, β) and cytoskeletal proteins (filamin A, β1-tubulin, actin), the subcellular appearance of α-granules (VWF), membranes (GPIbβ) and cytoskeleton (F-actin) throughout in vitro development. We demonstrate that FL MKs although smaller in size, spontaneously produce more proplatelets than BM MKs and at earlier stages express more β1-tubulin. In addition, early FL MKs show increased internal GPIbβ staining and present higher GPIbβ (early and late) and VWF (late stages) total fluorescence intensity (TFI)/cell size than BM MKs. BM MKs have up-regulated TPO signaling corresponding to their bigger size and ploidy, without changes in c-Mpl. Expressing endogenous β1-tubulin or the presence of heparin improves BM MKs ability to produce proplatelets. These data suggest that FL MKs undergo cytoplasmic maturation earlier than BM MKs and that this, in addition to higher β1-tubulin levels and GPIb, supported with an extensive F-actin network, could contribute to more efficient proplatelet formation in vitro.
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Affiliation(s)
- Ivana Bertović
- Department of Biotechnology, The University of Rijeka, Rijeka, Croatia
| | - Ana Bura
- Department of Biotechnology, The University of Rijeka, Rijeka, Croatia
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Lee SH, Ihn HJ, Park EK, Kim JE. S100 Calcium-Binding Protein P Secreted from Megakaryocytes Promotes Osteoclast Maturation. Int J Mol Sci 2021; 22:ijms22116129. [PMID: 34200172 PMCID: PMC8201154 DOI: 10.3390/ijms22116129] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/26/2022] Open
Abstract
Megakaryocytes (MKs) differentiate from hematopoietic stem cells and produce platelets at the final stage of differentiation. MKs directly interact with bone cells during bone remodeling. However, whether MKs are involved in regulating bone metabolism through indirect regulatory effects on bone cells is unclear. Here, we observed increased osteoclast differentiation of bone marrow-derived macrophages (BMMs) cultured in MK-cultured conditioned medium (MK CM), suggesting that this medium contains factors secreted from MKs that affect osteoclastogenesis. To identify the MK-secreted factor, DNA microarray analysis of the human leukemia cell line K562 and MKs was performed, and S100 calcium-binding protein P (S100P) was selected as a candidate gene affecting osteoclast differentiation. S100P was more highly expressed in MKs than in K562 cells, and showed higher levels in MK CM than in K562-cultured conditioned medium. In BMMs cultured in the presence of recombinant human S100P protein, osteoclast differentiation was promoted and marker gene expression was increased. The resorption area was significantly larger in S100P protein-treated osteoclasts, demonstrating enhanced resorption activity. Overall, S100P secreted from MKs promotes osteoclast differentiation and resorption activity, suggesting that MKs indirectly regulate osteoclast differentiation and activity through the paracrine action of S100P.
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Affiliation(s)
- Seung-Hoon Lee
- Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Korea;
- BK21 Four KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents, Department of Biomedical Science, Kyungpook National University, Daegu 41944, Korea
- Cell and Matrix Research Institute, Kyungpook National University, Daegu 41944, Korea;
| | - Hye Jung Ihn
- Cell and Matrix Research Institute, Kyungpook National University, Daegu 41944, Korea;
| | - Eui Kyun Park
- Department of Oral Pathology and Regenerative Medicine, School of Dentistry, IHBR, Kyungpook National University, Daegu 41944, Korea;
| | - Jung-Eun Kim
- Department of Molecular Medicine, School of Medicine, Kyungpook National University, Daegu 41944, Korea;
- BK21 Four KNU Convergence Educational Program of Biomedical Sciences for Creative Future Talents, Department of Biomedical Science, Kyungpook National University, Daegu 41944, Korea
- Cell and Matrix Research Institute, Kyungpook National University, Daegu 41944, Korea;
- Correspondence: ; Tel.: +82-53-420-4949
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5
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Martínez-Botía P, Acebes-Huerta A, Seghatchian J, Gutiérrez L. On the Quest for In Vitro Platelet Production by Re-Tailoring the Concepts of Megakaryocyte Differentiation. ACTA ACUST UNITED AC 2020; 56:medicina56120671. [PMID: 33287459 PMCID: PMC7761839 DOI: 10.3390/medicina56120671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 12/14/2022]
Abstract
The demand of platelet transfusions is steadily growing worldwide, inter-donor variation, donor dependency, or storability/viability being the main contributing factors to the current global, donor-dependent platelet concentrate shortage concern. In vitro platelet production has been proposed as a plausible alternative to cover, at least partially, the increasing demand. However, in practice, such a logical production strategy does not lack complexity, and hence, efforts are focused internationally on developing large scale industrial methods and technologies to provide efficient, viable, and functional platelet production. This would allow obtaining not only sufficient numbers of platelets but also functional ones fit for all clinical purposes and civil scenarios. In this review, we cover the evolution around the in vitro culture and differentiation of megakaryocytes into platelets, the progress made thus far to bring the culture concept from basic research towards good manufacturing practices certified production, and subsequent clinical trial studies. However, little is known about how these in vitro products should be stored or whether any safety measure should be implemented (e.g., pathogen reduction technology), as well as their quality assessment (how to isolate platelets from the rest of the culture cells, debris, microvesicles, or what their molecular and functional profile is). Importantly, we highlight how the scientific community has overcome the old dogmas and how the new perspectives influence the future of platelet-based therapy for transfusion purposes.
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Affiliation(s)
- Patricia Martínez-Botía
- Platelet Research Lab, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain; (P.M.-B.); (A.A.-H.)
- Department of Medicine, University of Oviedo, 33003 Oviedo, Spain
| | - Andrea Acebes-Huerta
- Platelet Research Lab, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain; (P.M.-B.); (A.A.-H.)
| | - Jerard Seghatchian
- International Consultancy in Strategic Safety/Quality Improvements of Blood-Derived Bioproducts and Suppliers Quality Audit/Inspection, London NW3 3AA, UK;
| | - Laura Gutiérrez
- Platelet Research Lab, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), 33011 Oviedo, Spain; (P.M.-B.); (A.A.-H.)
- Department of Medicine, University of Oviedo, 33003 Oviedo, Spain
- Correspondence:
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Davenport P, Liu ZJ, Sola-Visner M. Changes in megakaryopoiesis over ontogeny and their implications in health and disease. Platelets 2020; 31:692-699. [PMID: 32200697 PMCID: PMC8006558 DOI: 10.1080/09537104.2020.1742879] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/05/2019] [Accepted: 02/26/2020] [Indexed: 12/16/2022]
Abstract
A growing body of research has made it increasingly clear that there are substantial biological differences between fetal/neonatal and adult megakaryopoiesis. Over the last decade, studies revealed a developmentally unique uncoupling of proliferation, polyploidization, and cytoplasmic maturation in neonatal MKs that results in the production of large numbers of small, low ploidy, but mature MKs during this period of development, and identified substantial molecular differences between fetal/neonatal and adult MKs. This review will summarize our current knowledge on the developmental differences between fetal/neonatal and adult MKs, and recent advances in our understanding of the underlying molecular mechanisms, including newly described developmentally regulated pathways and miRNAs. We will also discuss the implications of these findings on the ways MKs interact with the environment, the response of neonates to thrombocytopenia, the pathogenesis of Down syndrome-transient myeloproliferative disorder (TMD), and the developmental stage specific-manifestations of congenital amegakaryocytic thrombocytopenia.
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Affiliation(s)
- Patricia Davenport
- Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School , Boston, MA, USA
| | - Zhi-Jian Liu
- Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School , Boston, MA, USA
| | - Martha Sola-Visner
- Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School , Boston, MA, USA
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7
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Lefrançais E, Looney MR. Platelet Biogenesis in the Lung Circulation. Physiology (Bethesda) 2019; 34:392-401. [PMID: 31577166 PMCID: PMC6957358 DOI: 10.1152/physiol.00017.2019] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 12/22/2022] Open
Abstract
Megakaryocytes are normal cellular components of the blood returning to the heart and entering the lungs, and historical data has pointed to a role of the lungs in platelet production. Recent studies using intravital microscopy have demonstrated that platelet release occurs in the lung from bone marrow megakaryocytes that embolize into the lung circulation.
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Affiliation(s)
- Emma Lefrançais
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Mark R Looney
- Departments of Medicine and Laboratory Medicine, University of California, San Francisco, CA
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8
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Kizilyer A, Singh MV, Singh VB, Suwunnakorn S, Palis J, Maggirwar SB. Inhibition of Tropomyosin Receptor Kinase A Signaling Negatively Regulates Megakaryopoiesis and induces Thrombopoiesis. Sci Rep 2019; 9:2781. [PMID: 30808933 PMCID: PMC6391490 DOI: 10.1038/s41598-019-39385-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/05/2018] [Indexed: 02/07/2023] Open
Abstract
Neurotrophin signaling modulates the differentiation and function of mature blood cells. The expression of neurotrophin receptors and ligands by hematopoietic and stromal cells of the bone marrow indicates that neurotrophins have the potential to regulate hematopoietic cell fate decisions. This study investigates the role of neurotrophins and Tropomyosin receptor kinases (Trk) in the development of megakaryocytes (MKs) and their progeny cells, platelets. Results indicate that primary human MKs and MK cells lines, DAMI, Meg-01 and MO7e express TrkA, the primary receptor for Nerve Growth Factor (NGF) signaling. Activation of TrkA by NGF enhances the expansion of human MK progenitors (MKPs) and, to some extent, MKs. Whereas, inhibition of TrkA receptor by K252a leads to a 50% reduction in the number of both MKPs and MKs and is associated with a 3-fold increase in the production of platelets. In order to further confirm the role of TrkA signaling in platelet production, TrkA deficient DAMI cells were generated using CRISPR-Cas9 technology. Comparative analysis of wild-type and TrkA-deficient Dami cells revealed that loss of TrkA signaling induced apoptosis of MKs and increased platelet production. Overall, these findings support a novel role for TrkA signaling in platelet production and highlight its potential as therapeutic target for Thrombocytopenia.
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Affiliation(s)
- Ayse Kizilyer
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Burdur Mehmet Akif Ersoy University, Burdur, Turkey
| | - Meera V Singh
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Vir B Singh
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Sumanun Suwunnakorn
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - James Palis
- Department of Pediatrics, Hematology and Oncology, University of Rochester Medical Center, Rochester, NY, United States of America
| | - Sanjay B Maggirwar
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY, United States of America.
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10
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Cortegano I, Serrano N, Ruiz C, Rodríguez M, Prado C, Alía M, Hidalgo A, Cano E, de Andrés B, Gaspar ML. CD45 expression discriminates waves of embryonic megakaryocytes in the mouse. Haematologica 2018; 104:1853-1865. [PMID: 30573502 PMCID: PMC6717566 DOI: 10.3324/haematol.2018.192559] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 12/14/2018] [Indexed: 12/14/2022] Open
Abstract
Embryonic megakaryopoiesis starts in the yolk sac on gestational day 7.5 as part of the primitive wave of hematopoiesis, and it continues in the fetal liver when this organ is colonized by hematopoietic progenitors between day 9.5 and 10.5, as the definitive hematopoiesis wave. We characterized the precise phenotype of embryo megakaryocytes in the liver at gestational day 11.5, identifying them as CD41++CD45-CD9++CD61+MPL+CD42c+ tetraploid cells that express megakaryocyte-specific transcripts and display differential traits when compared to those present in the yolk sac at the same age. In contrast to megakaryocytes from adult bone marrow, embryo megakaryocytes are CD45− until day 13.5 of gestation, as are both the megakaryocyte progenitors and megakaryocyte/erythroid-committed progenitors. At gestational day 11.5, liver and yolk sac also contain CD41+CD45+ and CD41+CD45− cells. These populations, and that of CD41++CD45−CD42c+ cells, isolated from liver, differentiate in culture into CD41++CD45−CD42c+ proplatelet-bearing megakaryocytes. Also present at this time are CD41−CD45++CD11b+ cells, which produce low numbers of CD41++CD45−CD42c+ megakaryocytes in vitro, as do fetal liver cells expressing the macrophage-specific Csf receptor-1 (Csf1r/CD115) from MaFIA transgenic mice, which give rise poorly to CD41++CD45−CD42c+ embryo megakaryocytes both in vivo and in vitro. In contrast, around 30% of adult megakaryocytes (CD41++CD45++CD9++CD42c+) from C57BL/6 and MaFIA mice express CD115. We propose that differential pathways operating in the mouse embryo liver at gestational day 11.5 beget CD41++CD45−CD42c+ embryo megakaryocytes that can be produced from CD41+CD45− or from CD41+CD45+ cells, at difference from those from bone marrow.
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Affiliation(s)
- Isabel Cortegano
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - Natalia Serrano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas (CBMSO-CSIC), Madrid
| | - Carolina Ruiz
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - Mercedes Rodríguez
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - Carmen Prado
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - Mario Alía
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - Andrés Hidalgo
- Area of Cell and Developmental Biology, Centro Nacional de Investigaciones Cardiovasculares, Madrid
| | - Eva Cano
- Neuroinflamation Unit, Chronic Diseases Research Program, Instituto de Salud Carlos III (ISCIII), Majadahonda, Spain
| | - Belén de Andrés
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
| | - María-Luisa Gaspar
- Department of Immunology, Centro Nacional de Microbiología, Instituto de Salud Carlos III (ISCIII), Majadahonda
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Cooper TT, Bell GI, Hess DA. Inhibition of Retinoic Acid Production Expands a Megakaryocyte-Enriched Subpopulation with Islet Regenerative Function. Stem Cells Dev 2018; 27:1449-1461. [PMID: 30039749 DOI: 10.1089/scd.2018.0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Islet regeneration is stimulated after transplantation of human umbilical cord blood (UCB) hematopoietic progenitor cells with high aldehyde dehydrogenase (ALDH)-activity into NOD/SCID mice with streptozotocin (STZ)-induced β cell ablation. ALDHhi progenitor cells represent a rare subset within UCB that will require expansion without the loss of islet regenerative functions for use in cell therapies. ALDHhi cells efficiently expand (>70-fold) under serum-free conditions; however, high ALDH-activity is rapidly diminished during culture coinciding with emergence of a committed megakaryocyte phenotype CD41+/CD42+/CD38+. ALDH-activity is also the rate-limiting step in retinoic acid (RA) production, a potent driver of hematopoietic differentiation. We have previously shown that inhibition of RA production during 9-day cultures, using diethylaminobenzaldehyde (DEAB) treatment, enhanced the expansion of ALDHhi cells (>20-fold) with vascular regenerative paracrine functions. Herein, we sought to determine if DEAB-treatment also expanded ALDHhi cells that retain islet regenerative function following intrapancreatic transplantation into hyperglycemic mice. After DEAB-treatment, expanded ALDHhi cell subset was enriched for CD34+/CD38- expression and demonstrated enhanced myeloid multipotency in vitro compared to the ALDHlo cell subset. Unfortunately, DEAB-treated ALDHhi cells did not support islet regeneration after transplantation. Conversely, expanded ALDHlo cells from DEAB-treated conditions reduced hyperglycemia, and increased islet number and cell proliferation in STZ-induced hyperglycemic NOD/SCID mice. DEAB-treated ALDHlo cells were largely committed to a CD41+/CD42+ megakaryocyte phenotype. Collectively, this study provides preliminary evidence that committed cells of the megakaryocyte-lineage support endogenous islet regeneration and/or function, and the retention of high ALDH-activity did not coincide with islet regenerative function after expansion under serum-free culture conditions.
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Affiliation(s)
- Tyler Thomas Cooper
- 1 Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University , London, Canada .,2 Molecular Medicine Research Laboratories, Krembil Centre for Stem Cell Biology, Robarts Research Institute , London, Canada
| | - Gillian I Bell
- 2 Molecular Medicine Research Laboratories, Krembil Centre for Stem Cell Biology, Robarts Research Institute , London, Canada
| | - David A Hess
- 1 Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University , London, Canada .,2 Molecular Medicine Research Laboratories, Krembil Centre for Stem Cell Biology, Robarts Research Institute , London, Canada
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12
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Megakaryocyte ontogeny: Clinical and molecular significance. Exp Hematol 2018; 61:1-9. [PMID: 29501467 DOI: 10.1016/j.exphem.2018.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/11/2018] [Accepted: 02/13/2018] [Indexed: 12/23/2022]
Abstract
Fetal megakaryocytes (Mks) differ from adult Mks in key parameters that affect their capacity for platelet production. However, despite being smaller, more proliferative, and less polyploid, fetal Mks generally mature in the same manner as adult Mks. The phenotypic features unique to fetal Mks predispose patients to several disease conditions, including infantile thrombocytopenia, infantile megakaryoblastic leukemias, and poor platelet recovery after umbilical cord blood stem cell transplantations. Ontogenic Mk differences also affect new strategies being developed to address global shortages of platelet transfusion units. These donor-independent, ex vivo production platforms are hampered by the limited proliferative capacity of adult-type Mks and the inferior platelet production by fetal-type Mks. Understanding the molecular programs that distinguish fetal versus adult megakaryopoiesis will help in improving approaches to these clinical problems. This review summarizes the phenotypic differences between fetal and adult Mks, the disease states associated with fetal megakaryopoiesis, and recent advances in the understanding of mechanisms that determine ontogenic Mk transitions.
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Nygaard G, Herfindal L, Asrud KS, Bjørnstad R, Kopperud RK, Oveland E, Berven FS, Myhren L, Hoivik EA, Lunde THF, Bakke M, Døskeland SO, Selheim F. Epac1-deficient mice have bleeding phenotype and thrombocytes with decreased GPIbβ expression. Sci Rep 2017; 7:8725. [PMID: 28821815 PMCID: PMC5562764 DOI: 10.1038/s41598-017-08975-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 07/17/2017] [Indexed: 11/16/2022] Open
Abstract
Epac1 (Exchange protein directly activated by cAMP 1) limits fluid loss from the circulation by tightening the endothelial barrier. We show here that Epac1-/- mice, but not Epac2-/- mice, have prolonged bleeding time, suggesting that Epac1 may limit fluid loss also by restraining bleeding. The Epac1-/- mice had deficient in vitro secondary hemostasis. Quantitative comprehensive proteomics analysis revealed that Epac1-/- mouse platelets (thrombocytes) had unbalanced expression of key components of the glycoprotein Ib-IX-V (GPIb-IX-V) complex, with decrease of GP1bβ and no change of GP1bα. This complex is critical for platelet adhesion under arterial shear conditions. Furthermore, Epac1-/- mice have reduced levels of plasma coagulation factors and fibrinogen, increased size of circulating platelets, increased megakaryocytes (the GP1bβ level was decreased also in Epac1-/- bone marrow) and higher abundance of reticulated platelets. Viscoelastic measurement of clotting function revealed Epac1-/- mice with a dysfunction in the clotting process, which corresponds to reduced plasma levels of coagulation factors like factor XIII and fibrinogen. We propose that the observed platelet phenotype is due to deficient Epac1 activity during megakaryopoiesis and thrombopoiesis, and that the defects in blood clotting for Epac1-/- is connected to secondary hemostasis.
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Affiliation(s)
- Gyrid Nygaard
- Department of Biomedicine, University of Bergen, Bergen, Norway
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Lars Herfindal
- Centre for Pharmacy, Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | - Ronja Bjørnstad
- Centre for Pharmacy, Department of Clinical Science, University of Bergen, Bergen, Norway
- Hospital Pharmacies Enterprise, Western Norway, Bergen, Norway
| | | | - Eystein Oveland
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Frode S Berven
- Department of Biomedicine, University of Bergen, Bergen, Norway
- The Proteomics Unit at the University of Bergen, Bergen, Norway
| | - Lene Myhren
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Erling A Hoivik
- Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Turid Helen Felli Lunde
- Department of Immunology and Transfusion Medicine, Haukeland University Hospital, Bergen, Norway
| | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Frode Selheim
- Department of Biomedicine, University of Bergen, Bergen, Norway.
- The Proteomics Unit at the University of Bergen, Bergen, Norway.
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Undi RB, Gutti U, Gutti RK. Role of let-7b/Fzd4 axis in mitochondrial biogenesis through wnt signaling: In neonatal and adult megakaryocytes. Int J Biochem Cell Biol 2016; 79:61-68. [DOI: 10.1016/j.biocel.2016.08.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/29/2016] [Accepted: 08/05/2016] [Indexed: 12/11/2022]
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Guo T, Wang X, Qu Y, Yin Y, Jing T, Zhang Q. Megakaryopoiesis and platelet production: insight into hematopoietic stem cell proliferation and differentiation. Stem Cell Investig 2015; 2:3. [PMID: 27358871 DOI: 10.3978/j.issn.2306-9759.2015.02.01] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 02/06/2015] [Indexed: 12/12/2022]
Abstract
Hematopoietic stem cells (HSCs) undergo successive lineage commitment steps to generate megakaryocytes (MKs) in a process referred to as megakaryopoiesis. MKs undergo a unique differentiation process involving endomitosis to eventually produce platelets. Many transcription factors participate in the regulation of this complex progress. Chemokines and other factors in the microenvironment where megakaryopoiesis and platelet production occur play vital roles in the regulation of HSC lineage commitment and MK maturation; among these factors, thrombopoietin (TPO) is the most important. Endomitosis is a vital process of MK maturation, and granules that are formed in MKs are important for platelet function. Proplatelets are firstly generated from mature MKs and then become platelets. The proplatelet production process was verified by novel studies that revealed that the mechanism is partially regulated by the invaginated membrane system (IMS), microtubules and Rho GTPases. The extracellular matrices (ECMs) and shear stress also affect and regulate the process while the mature MKs migrate from the marrow to the sub-endothelium region near the venous sinusoids leading to the release of platelets into the circulation. This review describes the entire process of megakaryopoiesis in detail, illustrates both the transcriptional and microenvironmental regulation of MKs and provides insight into platelet biogenesis.
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Affiliation(s)
- Tianyu Guo
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
| | - Xuejun Wang
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
| | - Yigong Qu
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
| | - Yu Yin
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
| | - Tao Jing
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
| | - Qing Zhang
- 1 State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China ; 2 Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, China
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Zhang W, Yu C, Huang B, Zhou FL, Huang HD, Li Q. Correlation between bone metastasis and thrombocytosis in pulmonary adenocarcinoma patients. Oncol Lett 2014; 9:762-768. [PMID: 25621048 PMCID: PMC4301510 DOI: 10.3892/ol.2014.2770] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 09/30/2014] [Indexed: 11/21/2022] Open
Abstract
Thrombocytosis is commonly observed in patients exhibiting a variety of malignancies, including pulmonary, gastrointestinal and hepatic cancer. In the present study, the correlation between distant metastasis and thrombocytosis was retrospectively reviewed in 308 cases of histopathologically confirmed pulmonary adenocarcinoma. The patients were classified as having thrombocytosis or not, based on their platelet counts upon diagnosis; thrombocytosis was documented in 82/308 patients (26.6%). A log-rank test indicated a statistically significant difference in survival between patients exhibiting thrombocytosis compared with patients not exhibiting thrombocytosis (P<0.001). In addition, the occurrence of distant metastasis and the survival period were correlated with the presence of thrombocytosis upon diagnosis. In descending order of frequency, metastases were documented at the following sites: Lymph nodes (218/308 patients; 70.8%), bone (138/308 patients; 44.8%), lung (93/308 patients; 30.2%), brain (67/308 patients; 21.8%), liver (46/308 patients; 4.9%), adrenal glands (11/308 patients; 3.6%) and kidneys (5/308 patients; 1.6%). Bone metastasis occurred significantly more frequently in patients exhibiting thrombocytosis (50/82 patients: 61.0%; P<0.05) compared with patients not exhibiting thrombocytosis (88/226 patients; 38.9%). Furthermore, according to univariate analysis, thrombocytosis, weight loss, an Eastern Cooperative Oncology Group performance status score of ≥2 points, anemia, increased erythrocyte sedimentation rate, and increased alkaline phosphatase (AKP) and carcinoembryonic protein (CEA) levels were risk factors for bone metastasis. According to multivariate analysis, thrombocytosis, weight loss, and increased AKP and CEA levels were correlated with bone metastasis. Therefore, patients exhibiting pulmonary adenocarcinoma and thrombocytosis have a higher risk of bone metastasis compared with patients not exhibiting thrombocytosis.
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Affiliation(s)
- Wei Zhang
- Department of Respiratory Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Chao Yu
- Department of Respiratory Medicine, No. 413 Hospital of People's Liberation Army, Zhoushan, Zhejiang 316000, P.R. China
| | - Bin Huang
- Department of Respiratory Medicine, No. 413 Hospital of People's Liberation Army, Zhoushan, Zhejiang 316000, P.R. China
| | - Feng-Liang Zhou
- Department of Respiratory Medicine, No. 413 Hospital of People's Liberation Army, Zhoushan, Zhejiang 316000, P.R. China
| | - Hai-Dong Huang
- Department of Respiratory Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
| | - Qiang Li
- Department of Respiratory Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, P.R. China
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Abstract
The fetal/neonatal hematopoietic system must generate enough blood cells to meet the demands of rapid growth. This unique challenge might underlie the high incidence of thrombocytopenia among preterm neonates. In this study, neonatal platelet production and turnover were investigated in newborn mice. Based on a combination of blood volume expansion and increasing platelet counts, the platelet mass increased sevenfold during the first 2 weeks of murine life, a time during which thrombopoiesis shifted from liver to bone marrow. Studies applying in vivo biotinylation and mathematical modeling showed that newborn and adult mice had similar platelet production rates, but neonatal platelets survived 1 day longer in circulation. This prolonged lifespan fully accounted for the rise in platelet counts observed during the second week of murine postnatal life. A study of pro-apoptotic and anti-apoptotic Bcl-2 family proteins showed that neonatal platelets had higher levels of the anti-apoptotic protein Bcl-2 and were more resistant to apoptosis induced by the Bcl-2/Bcl-xL inhibitor ABT-737 than adult platelets. However, genetic ablation or pharmacologic inhibition of Bcl-2 alone did not shorten neonatal platelet survival or reduce platelet counts in newborn mice, indicating the existence of redundant or alternative mechanisms mediating the prolonged lifespan of neonatal platelets.
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Emmrich S, Henke K, Hegermann J, Ochs M, Reinhardt D, Klusmann JH. miRNAs can increase the efficiency of ex vivo platelet generation. Ann Hematol 2012; 91:1673-84. [PMID: 22763947 DOI: 10.1007/s00277-012-1517-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 06/12/2012] [Indexed: 01/01/2023]
Abstract
The process of megakaryopoiesis culminates in the release of platelets, the pivotal cellular component for hemostasis and wound healing. The regulatory architecture including the modulatory role of microRNAs, which underlies megakaryocytic maturation and platelet formation, is incompletely understood, precluding the ex vivo generation of sufficient platelet numbers for transfusion medicine. We derived a highly efficient differentiation protocol to produce mature polyploid megakaryocytes and functional platelets from CD34⁺-hematopoietic stem and progenitor cells by comparing previously published approaches. Our megakaryocytic culture conditions using the cytokines SCF, TPO, IL-9, and IL-6 include nicotinamide and Rho-associated kinase (ROCK) inhibitor Y27632 as contextual additives. The potency of our novel megakaryocytic differentiation protocol was validated using cord blood and peripheral blood human hematopoietic stem and progenitor cells. Using this novel megakaryocytic differentiation protocol, we characterized the modulatory capacity of several miRNAs highly expressed in normal megakaryocytic cells or malignant blasts from patients with megakaryoblastic leukemia. Overexpression of candidate microRNAs was achieved by lentiviral transduction of CD34⁺-hematopoietic stem and progenitor cells prior to differentiation. We revealed miR-125b and miR-660 as enhancers of polyploidization, as well as platelet output of megakaryocytes. The oncogene miR-125b markedly expanded the number of megakaryocytes during in vitro culture. Conversely, the miR-23a/27a/24-2 cluster, which is highly expressed in normal megakaryocytes, blocked maturation and platelet formation. Our study on the utilization of microRNAs in conjunction with a highly efficient differentiation protocol constitutes another step towards ex vivo platelet manufacturing on a clinically relevant scale.
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Affiliation(s)
- Stephan Emmrich
- Department of Pediatric Hematology and Oncology, Hannover Medical School, Hannover, Germany
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19
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Abstract
PURPOSE OF REVIEW It has become increasingly clear that there are substantial biological differences between fetal/neonatal and adult megakaryopoiesis. Over the last 18 months, studies challenged the paradigm that neonatal megakaryocytes are immature and revealed a developmentally unique uncoupling of proliferation, polyploidization, and cytoplasmic maturation. Several studies also described substantial molecular differences between fetal/neonatal and adult megakaryocytes involving transcription factors, signaling pathways, cytokine receptors, and microRNAs. RECENT FINDINGS This review will summarize our current knowledge on the developmental differences between fetal/neonatal and adult megakaryocytes, and recent advances in the underlying molecular mechanisms, including differences in transcription factors, in the response to thrombopoietin (Tpo), and newly described developmentally regulated signaling pathways. We will also discuss the implications of these findings on the way megakaryocytes interact with the environment, the response of neonates to thrombocytopenia, and the pathogenesis of Down syndrome-transient myeloproliferative disorder (TMD) and Down syndrome-acute megakaryoblastic leukemia (DS-AMKL). SUMMARY A better characterization of the molecular differences between fetal/neonatal and adult megakaryocytes is critical to elucidating the pathogenesis of a group of disorders that selectively affect fetal/neonatal megakaryocyte progenitors, including the thrombocytopenia-absent radius (TAR) syndrome, Down syndrome-TMD or Down syndrome-AMKL, and the delayed platelet engraftment following cord blood transplantation.
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Developmental differences in megakaryocytopoiesis are associated with up-regulated TPO signaling through mTOR and elevated GATA-1 levels in neonatal megakaryocytes. Blood 2011; 117:4106-17. [PMID: 21304100 DOI: 10.1182/blood-2010-07-293092] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Multiple observations support the existence of developmental differences in megakaryocytopoiesis. We have previously shown that neonatal megakaryocyte (MK) progenitors are hyperproliferative and give rise to MKs smaller and of lower ploidy than adult MKs. Based on these characteristics, neonatal MKs have been considered immature. The molecular mechanisms underlying these differences are unclear, but contribute to the pathogenesis of disorders of neonatal megakaryocytopoiesis. In the present study, we demonstrate that low-ploidy neonatal MKs, contrary to traditional belief, are more mature than adult low-ploidy MKs. These mature MKs are generated at a 10-fold higher rate than adult MKs, and result from a developmental uncoupling of proliferation, polyploidization, and terminal differentiation. This pattern is associated with up-regulated thrombopoietin (TPO) signaling through mammalian target of rapamycin (mTOR) and elevated levels of full-length GATA-1 and its targets. Blocking of mTOR with rapamycin suppressed the maturation of neonatal MKs without affecting ploidy, in contrast to the synchronous inhibition of polyploidization and cytoplasmic maturation in adult MKs. We propose that these mechanisms allow fetuses/neonates to populate their rapidly expanding bone marrow and intravascular spaces while maintaining normal platelet counts, but also set the stage for disorders restricted to fetal/neonatal MK progenitors, including the Down syndrome-transient myeloproliferative disorder and the thrombocytopenia absent radius syndrome.
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Ferrer-Marin F, Liu ZJ, Gutti R, Sola-Visner M. Neonatal thrombocytopenia and megakaryocytopoiesis. Semin Hematol 2011; 47:281-8. [PMID: 20620440 DOI: 10.1053/j.seminhematol.2010.04.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Thrombocytopenia is common among sick neonates, affecting 20% to 35% of all patients admitted to the neonatal intensive care unit (NICU). While most cases of neonatal thrombocytopenia are mild or moderate and resolve within 7 to 14 days with appropriate therapy, 2.5% to 5% of NICU patients develop severe thrombocytopenia, sometimes lasting for several weeks and requiring >20 platelet transfusions. The availability of thrombopoietic agents offers the possibility of decreasing the number of platelet transfusions and potentially improving the outcomes of these infants. However, adding thrombopoietin (TPO) mimetics to the therapeutic armamentarium of neonatologists will require careful attention to the substantial developmental differences between neonates and adults in the process of megakaryocytopoiesis and in their responses to TPO. Taken together, the available data suggest that TPO mimetics will stimulate platelet production in neonates, but might do so through different mechanisms and at different doses than those established for adults. In addition, the specific groups of thrombocytopenic neonates most likely to benefit from therapy with TPO mimetics need to be defined, and the potential nonhematological effects of these agents on the developing organism need to be considered. This review summarizes our current understanding of neonatal megakaryocytopoiesis, and examines in detail the developmental factors relevant to the potential use of TPO mimetics in neonates.
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Affiliation(s)
- Francisca Ferrer-Marin
- Division of Newborn Medicine, Children's Hospital Boston and Harvard Medical School, Boston, MA 02115, USA
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22
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Feng Y, Chen X, Gao L. Hypothesis: Human Umbilical Cord Blood-derived Stromal Cells Promote Megakaryocytopoiesis Through the Influence of SDF-1 and PECAM-1. Cell Biochem Biophys 2010; 58:25-30. [DOI: 10.1007/s12013-010-9086-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Hu Z, Slayton WB, Rimsza LM, Bailey M, Sallmon H, Sola-Visner MC. Differences between newborn and adult mice in their response to immune thrombocytopenia. Neonatology 2010; 98:100-8. [PMID: 20134184 PMCID: PMC2914362 DOI: 10.1159/000280413] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Accepted: 08/18/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Sick neonates frequently develop severe thrombocytopenia. OBJECTIVE AND METHODS In order to test the ability of fetal mice to increase their megakaryocyte size and ploidy in response to thrombocytopenia, we injected an antiplatelet antibody (MWReg30) into pregnant mice daily for 7 days, and into nonpregnant adult mice to serve as controls. After that time, platelet counts were obtained and megakaryocytes in the bone marrow, liver, and spleen were stained with anti-von Willebrand factor antibody, individually measured, and quantified. RESULTS Our study demonstrated that megakaryocytopoiesis in newborn mice shares many features of human fetal/neonatal megakaryocytopoiesis, including the small size of megakaryocytes. In response to thrombocytopenia, adult mice increased megakaryocyte volume and concentration, primarily in the spleen. Newborn mice, in contrast, increased the megakaryocyte concentration in the spleen, but exhibited no increase in megakaryocyte volume in any of the organs studied. In fact, the megakaryocyte mass was significantly lower in the bone marrow of thrombocytopenic neonates than in age-matched controls. CONCLUSIONS We concluded that fetuses have a limited ability to increase their megakaryocyte mass in response to consumptive thrombocytopenia, compared to adult mice. These observations provide further evidence for the existence of biological differences between fetal/neonatal and adult megakaryocytopoiesis.
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Affiliation(s)
- Zhongbo Hu
- Department of Pediatrics, University of Florida, Gainesville, FL, USA
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24
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Sola-Visner M, Sallmon H, Brown R. New insights into the mechanisms of nonimmune thrombocytopenia in neonates. Semin Perinatol 2009; 33:43-51. [PMID: 19167581 PMCID: PMC2674325 DOI: 10.1053/j.semperi.2008.10.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Thrombocytopenia affects up to 35% of all patients admitted to the neonatal intensive care unit. The causes of thrombocytopenia in neonates are very diverse and include immune and nonimmune disorders. Most cases of thrombocytopenia encountered in the neonatal intensive care unit are nonimmune, and these will constitute the focus of this review. Specifically, we first discuss the biological differences between neonatal and adult megakaryocytopoiesis, which contribute to explain the vulnerability of neonates to develop thrombocytopenia. Next, we review new diagnostic tools that have allowed for a better evaluation of platelet production in neonates, without having to obtain a bone marrow sample. Finally, we summarize our current understanding of the mechanisms underlying the thrombocytopenia in several common neonatal conditions, such as chronic intrauterine hypoxia, sepsis and necrotizing enterocolitis, and viral infections. A better understanding of the mechanisms underlying these varieties of thrombocytopenia is critical to develop disease-specific treatment protocols and to begin to entertain the possibility of using novel thrombopoietic growth factors to treat selected neonates with severe thrombocytopenia.
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Affiliation(s)
- Martha Sola-Visner
- Division of Newborn Medicine, Children's Hospital Boston, Boston, MA 02115, USA.
| | - Hannes Sallmon
- Division of Newborn Medicine, Children’s Hospital Boston, Boston, MA,Department of Neonatology, Campus Virchow-Klinikum, Charité – Universitätsmedizin Berlin, Germany
| | - Rachel Brown
- Division of Newborn Medicine, Nationwide Children’s Hospital, Columbus, OH
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Roles of focal adhesion kinase (FAK) in megakaryopoiesis and platelet function: studies using a megakaryocyte lineage specific FAK knockout. Blood 2007; 111:596-604. [PMID: 17925492 DOI: 10.1182/blood-2007-05-089680] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Focal adhesion kinase (FAK) plays a key role in mediating signaling downstream of integrins and growth factor receptors. In this study, we determined the roles of FAK in vivo by generating a megakaryocyte lineage-specific FAK-null mouse (Pf4-Cre/FAK-floxed). Megakaryocyte and platelet FAK expression was ablated in Pf4-Cre/FAK-floxed mice without affecting expression of the FAK homologue PYK2, although PYK2 phosphorylation was increased in FAK-/- megakaryocytes in response to fibrinogen. Megakaryopoiesis is greatly enhanced in Pf4-Cre/FAK-floxed mice, with significant increases in megakaryocytic progenitors (CFU-MK), mature megakaryocytes, megakaryocyte ploidy, and moderate increases in resting platelet number and platelet recovery following a thrombocytopenic stress. Thrombopoietin (Tpo)-mediated activation of Lyn kinase, a negative regulator of megakaryopoiesis, is severely attenuated in FAK-null megakaryocytes compared with wild-type controls. In contrast, Tpo-mediated activation of positive megakaryopoiesis regulators such as ERK1/2 and AKT is increased in FAK-null megakaryocytes, providing a plausible explanation for the observed increases in megakaryopoiesis in these mice. In Pf4-Cre/FAK-floxed mice, rebleeding times are significantly increased, and FAK-null platelets exhibit diminished spreading on immobilized fibrinogen. These studies establish clear roles for FAK in megakaryocyte growth and platelet function, setting the stage for manipulation of this component of the Tpo signaling apparatus for therapeutic benefit.
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Li XM, Hu Z, Sola-Visner M, Hensel S, Garner R, Zafar AB, Wingard JR, Jorgensen ML, Fisher RC, Scott EW, Slayton WB. Sites and kinetics of donor thrombopoiesis following transplantation of whole bone marrow and progenitor subsets. Exp Hematol 2007; 35:1567-79. [PMID: 17697746 DOI: 10.1016/j.exphem.2007.06.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 06/12/2007] [Accepted: 06/14/2007] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Little is known about the sites and kinetics of thrombopoiesis following bone marrow transplant. The spleen is a site of hematopoiesis in a healthy mouse, and hematopoietic activity increases in response to stress. We hypothesized that the spleen is a major site of early post-transplant thrombopoiesis. METHODS We transplanted whole bone marrow (WBM) or lineage depleted progenitor subsets fractionated based on expression of c-kit and Sca-1 from transgenic mice expressing green fluorescent protein into lethally irradiated C57BL/6 recipients. We also transplanted whole bone marrow cells into healthy and splenectomized mice. Post-transplant megakaryopoiesis was assessed by measuring circulating platelet number, percent donor-derived platelets, bone marrow cellularity, splenic weight, megakaryocyte size, and megakaryocyte concentration from hour 3 to day 28 post transplant. RESULTS Following transplant, circulating donor-derived platelets were derived only from c-kit expressing subsets. Donor-derived platelets first appeared on post-transplant day five. Splenectomy reduced the number of these earliest circulating platelets. Splenic megakaryopoiesis increased dramatically from day 7-14 post-transplant. However, splenectomy accelerated platelet engraftment during this time frame. CONCLUSION Overall, these results demonstrate that the first platelets are produced by c-kit expressing megakaryocyte progenitors in the bone marrow and spleen. After post-transplant day 5, the net effect of the spleen on thrombopoiesis is to slow engraftment due to immune effects or hypersplenism.
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Affiliation(s)
- Xiao-Miao Li
- Department of Pediatrics, University of Florida, Gainesville, USA
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27
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Abstract
Megakaryocytopoiesis is the process that leads to the production of platelets. This process involves the commitment of multipotent hematopoietic stem cells toward megakaryocyte (MK) progenitors, the proliferation and differentiation of MK progenitors, the polyploidization of MK precursors and the maturation of MK. Mature MK produce platelets by cytoplasmic fragmentation occurring through a dynamic and regulated process, called proplatelet formation, and consisting of long pseudopodial elongations that break in the blood flow. Recent insights have demonstrated that the MK and erythroid lineages are tightly associated at both the cellular and molecular levels, especially in the transcription factors that regulate their differentiation programs. Megakaryocytopoiesis is regulated by two types of transcription factors, those regulating the differentiation process, such as GATA-1, and those regulating proplatelet formation, such as NF-E2. The humoral factor thrombopoietin (TPO) is the primary regulator of MK differentiation and platelet production through the stimulation of its receptor MPL. Numerous acquired or congenital pathologies of the MK lineage are now explained by molecular abnormalities in the activity of the transcription factors involved in megakaryocytopoiesis, in the Tpo or c-mpl genes, as well as in signaling molecules associated with MPL. The recent development of MPL agonists may provide efficient agents for the treatment of some thrombocytopenias.
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Affiliation(s)
- Y Chang
- INSERM, Institut Gustave Roussy, Université Paris XI, Villejuif, France
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28
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Ignatz M, Sola-Visner M, Rimsza LM, Fuchs D, Shuster JJ, Li XM, Jotwani A, Staba S, Wingard JR, Hu Z, Slayton WB. Umbilical cord blood produces small megakaryocytes after transplantation. Biol Blood Marrow Transplant 2007; 13:145-50. [PMID: 17241920 DOI: 10.1016/j.bbmt.2006.10.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2006] [Accepted: 10/19/2006] [Indexed: 11/22/2022]
Abstract
Delayed platelet engraftment is a major complication of umbilical cord blood (CB) transplantation. Megakaryocytes derived from CB in vitro are smaller than megakaryocytes derived from bone marrow (BM) or mobilized peripheral blood from adults. Small megakaryocyte size may contribute to delayed platelet engraftment. To test whether small size persists after transplantation, we measured megakaryocyte size, concentration, and maturational stage in BM biopsy specimens obtained after transplantation in archived BM samples from patients receiving CB (CB group, n = 10) versus mobilized peripheral blood or BM transplantation (BM group, n = 9). Megakaryocytes in the postengraftment BM samples were significantly smaller in the CB group than in the BM group (median diameter, 16.7 vs 22.0 microm). There were no significant differences in megakaryocyte concentration or maturational stage between the CB and BM groups. For the first time, we demonstrate that the attainment of adult size in CB-derived megakaryocytes is delayed after human CB transplantation.
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Affiliation(s)
- Mark Ignatz
- Department of Pediatrics, University of Florida, Gainesville, Florida, USA
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29
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Pastos KM, Slayton WB, Rimsza LM, Young L, Sola-Visner MC. Differential effects of recombinant thrombopoietin and bone marrow stromal-conditioned media on neonatal versus adult megakaryocytes. Blood 2006; 108:3360-2. [PMID: 16888093 PMCID: PMC1895431 DOI: 10.1182/blood-2006-04-018036] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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.
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Affiliation(s)
- Karen M Pastos
- Shands Cancer Center, University of Florida, Gainesville, FL, USA
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30
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Sun L, Hwang WYK, Aw SE. Biological characteristics of megakaryocytes: Specific lineage commitment and associated disorders. Int J Biochem Cell Biol 2006; 38:1821-6. [PMID: 16730215 DOI: 10.1016/j.biocel.2006.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 03/21/2006] [Accepted: 03/21/2006] [Indexed: 10/24/2022]
Abstract
Megakayocytes (Megakaryocytes) are among the rarest type of haematopoietic cells and highly specialized precursors for platelets. Normal mature megakaryocytes are, perhaps, the largest cells in the marrow. In contrast, their annucleated platelets progeny are the smallest subcellular fragments in the circulation, which in spite of their size, play crucial roles in thrombostasis and haemostasis. Megakaryopoiesis involves complicated and multi-step biological processes. Research over the last decade has resulted in certain important new discoveries, such as the specific megakaryocyte-forming haematopoietic stem cell (HSC) subpopulation, thrombopoietin (Tpo), formation and release of platelets, etc. Substantial understanding of the specific lineage commitment, differentiation, and the molecular regulatory mechanisms of megakaryopoiesis has also been achieved. Despite existing controversies and questions, megakaryopoiesis remains an exciting field in biomedical research. Certain recent biological findings as well as future research in megakaryopoiesis are summarised in this article. Certain pathological changes associated with megakaryocytes, such as immune thrombocytopenia purpura (ITP), acute megakayoblastic leukaemia, etc., are also discussed in this article.
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Affiliation(s)
- Li Sun
- Department of Clinical Research, Singapore General Hospital, Outram Road, Singapore 169608, Republic of Singapore.
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