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Hamad MA, Schanze N, Schommer N, Nührenberg T, Duerschmied D. Reticulated Platelets-Which Functions Have Been Established by In Vivo and In Vitro Data? Cells 2021; 10:cells10051172. [PMID: 34065800 PMCID: PMC8150321 DOI: 10.3390/cells10051172] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/29/2021] [Accepted: 05/10/2021] [Indexed: 12/18/2022] Open
Abstract
Reticulated platelets (RP) are the youngest platelet fraction released into the circulation. These immature platelets have increased RNA content, a larger cell volume, more dense granules, higher levels of surface activation markers and are thought to be more reactive compared to their mature counterparts. RP have been associated with cardiovascular disease, diabetes and increased mortality. Yet only a few animal studies investigating RP have been conducted so far and further investigations are warranted. Established methods to count RP are flow cytometry (staining with thiazole orange or SYTO13) or fully automated hematology analyzers (immature platelet fraction, IPF). IPF has been established as a diagnostic parameter in thrombocytopenia, cardiovascular disease and, in particular, the response to antiplatelet therapy. This review seeks to provide an overview of the key features of RP as well as preanalytical and analytical aspects that need to be considered when working with this platelet population.
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Affiliation(s)
- Muataz Ali Hamad
- Department of Cardiology and Angiology I, Heart Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg im Breisgau, Germany; (N.S.); (N.S.); (D.D.)
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Faculty of Biology, University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Correspondence: ; Tel.: +49-761-270-70470
| | - Nancy Schanze
- Department of Cardiology and Angiology I, Heart Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg im Breisgau, Germany; (N.S.); (N.S.); (D.D.)
| | - Nicolas Schommer
- Department of Cardiology and Angiology I, Heart Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg im Breisgau, Germany; (N.S.); (N.S.); (D.D.)
| | - Thomas Nührenberg
- Department of Cardiology and Angiology II, Heart Center, Faculty of Medicine, University of Freiburg, 79189 Bad Krozingen, Germany;
| | - Daniel Duerschmied
- Department of Cardiology and Angiology I, Heart Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg im Breisgau, Germany; (N.S.); (N.S.); (D.D.)
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Dusse LMS, Freitas LG. Clinical applicability of reticulated platelets. Clin Chim Acta 2014; 439:143-7. [PMID: 25451948 DOI: 10.1016/j.cca.2014.10.024] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 10/07/2014] [Accepted: 10/15/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Reticulated platelets (RPs), immature platelets newly released from the bone marrow into the circulation, have a high content of ribonucleic acid and are larger and more active in thrombus formation. OBJECTIVE This review compiles articles that evaluated RP in order to establish their clinical significance. DISCUSSION RPs increase when platelet production rises and decrease when production falls. As such, the measurement of circulating RPs allows the assessment of thrombocytopenia, i.e., bone marrow production or peripheral destruction. CONCLUSION RPs are a promising laboratory tool for evaluation of idiopathic thrombocytopenia (differentiating hypoproduction from accelerated platelet destruction), chemotherapy and after stem cell transplantation (predicting platelet recovery) and thrombocytosis (estimating platelet turnover). Additional randomized and well controlled clinical studies are required to clearly establish the significance of circulating RPs in other clinical conditions.
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Affiliation(s)
- Luci Maria SantAna Dusse
- Department of Clinical and Toxicological Analysis, Faculty of Pharmacy-Universidade Federal de Minas Gerais, Brazil.
| | - Letícia Gonçalves Freitas
- Department of Clinical and Toxicological Analysis, Faculty of Pharmacy-Universidade Federal de Minas Gerais, Brazil
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Everds N, Li N, Bailey K, Fort M, Stevenson R, Jawando R, Salyers K, Jawa V, Narayanan P, Stevens E, He C, Nguyen MP, Tran S, Doyle N, Poitout-Belissent F, Jolette J, Xu C, Sprugel K. Unexpected Thrombocytopenia and Anemia in Cynomolgus Monkeys Induced by a Therapeutic Human Monoclonal Antibody. Toxicol Pathol 2013; 41:951-69. [DOI: 10.1177/0192623312474727] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cynomolgus monkeys dosed with a therapeutic monoclonal antibody (mAbY.1) at ≥50 mg/kg had unexpected acute thrombocytopenia (nadir ∼3,000 platelets/µl), sometimes with decreases in red cell mass. Increased activated macrophages, mitotic figures, and erythrophagocytosis were observed in the spleen. Binding of mAbY.1 to cynomolgus peripheral blood cells could not be detected in vitro. mAbY.1 induced phagocytosis of platelets by peripheral blood monocytes from cynomolgus monkeys, but not from humans. mAbs sharing the same constant domain (Fc) sequences, but differing from mAbY.1 in their variable domains, bound competitively to and had similar biological activity against the intended target. None of these antibodies had hematologic liabilities in vitro or in vivo. Neither the F(ab’)2 portion of mAbY.1 nor the F(ab’)2 portion on an aglycosylated Fc (IgG1) framework caused phagocytosis of platelets in vitro. These data suggest that the hematologic effects of mAbY.1 in cynomolgus monkeys likely occurred through an off-target mechanism, shown to be driven by 1 to 3 amino acid differences in the light chain. The hematologic effects made mAbY.1 an unsuitable candidate for further development as a therapeutic agent. This example demonstrates that nonclinical safety studies may be essential for understanding off-target effects of mAbs prior to clinical trials.
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Affiliation(s)
| | - Nianyu Li
- Amgen Inc., Seattle, Washington, USA
| | - Keith Bailey
- Oklahoma State University, Stillwater, Oklahoma, USA
| | | | | | | | - Kevin Salyers
- Amgen Inc., Thousand Oaks, California, USA
- Kevin Salyers is deceased
| | - Vibha Jawa
- Amgen Inc., Thousand Oaks, California, USA
| | | | | | - Ching He
- Amgen Inc., Seattle, Washington, USA
| | | | - Sam Tran
- Amgen Inc., Seattle, Washington, USA
| | - Nancy Doyle
- Charles River Preclinical Services Montreal, Senneville, Quebec, Canada
| | | | - Jacquelin Jolette
- Charles River Preclinical Services Montreal, Senneville, Quebec, Canada
| | - Cen Xu
- Amgen Inc., Thousand Oaks, California, USA
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