High levels of reticulated platelets and thrombopoietin characterize fetal thrombopoiesis

Jilma‐Stohlawetz, Petra; Homoncik, Monika; Jilma, Bernd; Folman, Claudia C.; Borne, A. E. G. K. Von Dem; Bernaschek, Gerhard; Deutinger, Josef; Ulm, Barbara; Eppel, Wolfgang; Panzer, Simon

doi:10.1046/j.1365-2141.2001.02524.x

Cited by 29 publications

(21 citation statements)

References 15 publications

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“…Our studies showed no change in derived platelet half-life after megakaryocytes were grown in the presence of two inhibitors of ADAM17, GM6001 and TAP-1 (Supplemental Figure 2, A and B). An alternative explanation for the shortened half-life is that most of our studies were performed with FL megakaryocytes, and fetal platelets have a shorter half-life compared with adult platelets (18). However, cultured infused adult BM megakaryocytes produced a similar delay in appearance and short half-life ( Figure 1F).…”

Section: Resultsmentioning

confidence: 83%

Infusion of mature megakaryocytes into mice yields functional platelets

Fuentes¹,

Wang²,

Hirsch³

et al. 2010

J. Clin. Invest.

109

131

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Thrombopoiesis, the process by which circulating platelets arise from megakaryocytes, remains incompletely understood. Prior studies suggest that megakaryocytes shed platelets in the pulmonary vasculature. To better understand thrombopoiesis and to develop a potential platelet transfusion strategy that is not dependent upon donors, of which there remains a shortage, we examined whether megakaryocytes infused into mice shed platelets. Infused megakaryocytes led to clinically relevant increases in platelet numbers. The released platelets were normal in size, displayed appropriate surface markers, and had a near-normal circulating half-life. The functionality of the donor-derived platelets was also demonstrated in vivo. The infused megakaryocytes mostly localized to the pulmonary vasculature, where they appeared to shed platelets. These data suggest that it may be unnecessary to generate platelets from ex vivo grown megakaryocytes to achieve clinically relevant increases in platelet numbers. IntroductionWhile the number of platelet donors is increasing, there is still a significant donor shortage due to the growing population of patients with serious illnesses associated with thrombocytopenia and hemorrhage (1). The use of donor-derived platelets raises the following concerns: variability of quality and quantity, risk of infectious transmission, short lifespan of stored platelets, bacterial contamination during storage, and development of alloantibodies in multi-transfused patients. These problems highlight a need for new strategies to generate platelets for infusion therapy. Thrombopoiesis, the process by which circulating platelets arise from megakaryocytes remains incompletely understood. In vitro studies suggest that platelets form nodes at tips of proplatelet strands (2). However, direct visualization of live calvaria marrow using multiphoton intravital microscopy suggests that megakaryocytes release large cytoplasmic fragments into the vasculature (3), which must then undergo reorganization into platelets. Studies based on morphologic analysis and quantification of megakaryocyte-like polyploid nuclei in the pulmonary venous system suggested that megakaryocytes release platelets in the lungs (4). Derivation of platelets from megakaryocytes in culture was first reported in 1995 (5) but has been difficult to quantitatively upscale. To date, the best published result from infused in vitro produced platelets used irradiated mice with low platelet counts (~10 4 /μl) (6). Peak percent donor platelet counts were still only 1%-2%. Given the limited success by which platelets have been generated ex vivo, we examined whether infused megakaryocytes release platelets in vivo. We found that by infusing ex vivo generated murine megakaryocytes into mice, we can achieve an approximately 100-fold increase in recipient platelet count over prior published results, achieving clinically relevant levels of donor platelets. These platelets have a slightly shorter

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Section: Resultsmentioning

confidence: 83%

Infusion of mature megakaryocytes into mice yields functional platelets

Fuentes¹,

Wang²,

Hirsch³

et al. 2010

J. Clin. Invest.

109

131

View full text Add to dashboard Cite

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“…von Willebrand factor antigen level (VWF‐Ag) was measured with a fully automated simultaneous thermal analyser (STA) using the VWF‐Liatest (Diagnostica Stago, Paris, France), because VWF‐Ag levels influence CEPI‐CT values. Surface expression of GpIb (CD42b) was measured by flow cytometry from whole citrated blood as described previously (Jilma‐Stohlawetz et al, 2001).…”

Section: Methodsmentioning

confidence: 99%

Glycoprotein Ib polymorphisms influence platelet plug formation under high shear rates

et al. 2003

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Summary. Platelet polymorphisms (Kozak, VNTR and HPA-2) within glycoprotein (GP)Iba may be associated with an increased risk of arterial thrombosis. However, the functional role of these polymorphisms has not been clarified. Their influence on platelet plug formation under high shear rates was, therefore, examined in 233 healthy individuals. Collagen-adrenaline-induced closure time was shorter in carriers of the C/D versus C/C VNTR allele and in homozygotes with the ()5)T/T versus ()5)C/T Kozak genotype as determined by novel polymerase chain reaction methods. The HPA-2 genotype had no effects, and the density of GPIba molecules was not influenced by GPIba genotypes.

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“…The reduced quantity and/ or longevity of platelets generated in vitro from ES (or G1ME2) cell-and FL-derived megakaryocytes could be due to suboptimal culture conditions that fail to support full maturation. Alternatively, megakaryocytes from ES cells and fetal tissues are biologically distinct from adult megakaryocytes and their platelet progeny may have inherently reduced life spans (28)(29)(30). Human ES cell-derived megakaryocytes are believed to approximate those derived from early embryonic yolk sacs (31).…”

Section: Methodsmentioning

confidence: 99%