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Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal platelet function, which can subsequently lead to impaired hemostasis. In the past decades, humanized mouse models (HMMs), that are mice engrafted with human cells or genes, have been widely used in different research areas including immunology, oncology, and virology. With advances of the development of immunodeficient mice, the engraftment, and reconstitution of functional human platelets in HMM permit studies of occurrence and development of platelet disorders including IT and treatment strategies. This article mainly reviews the development of humanized mice models, the construction methods, research status, and problems of using humanized mice for the in vivo study of human thrombopoiesis. Humanized mouse models (HMMs) refer to immunodeficient mice that have been used for the investigation of human hematopoiesis and immunity for years. With engrafted human hematopoietic stem cells (HSCs), the differentiation process of HSCs and re-construction of platelets can be monitored in the mice. Until now, several strains of HMMs have been used in the studies of inherited thrombocytopenia (IT), a genetic disorder associated with low platelet count in the blood. In this study, we reviewed the development of these HMMs in IT studies, compared the different sources of HSCs transplanted into HMMs and summarize the strategies of HSC transplantation in HMMs. The Kit−/− immunodeficient mice showed effectively long-term and stable implantation of human HSC without irradiation and higher implantation levels, and they also support multilinear differentiation of human HSC, such as platelets and red blood cells. The source and count of HSCs and the transplantation strategy may also impact the result. This study provides a basis information for HMMs used in IT and will help other investigators in this field choosing the right research plan. [ABSTRACT FROM AUTHOR]

Megakaryocytes (MKs) are the unique non-pathological cells that undergo polyploidization in mammals. The polyploid formation is critical for understanding the MK biology, and transcriptional regulation is involved in the differentiation and maturation of MKs. However, little is known about the functions of transcriptional elongation factors in the MK polyploidization. In this study, we investigated the role of transcription elongation factor EloA in the polyploidy formation during the MK differentiation. We found that EloA was highly expressed in the erythroleukemia cell lines HEL and K562. Knockdown of EloA in HEL cell line was shown to impair the phorbol myristate acetate (PMA) induced polyploidization process, which was used extensively to model megakaryocytic differentiation. Selective over-expression of EloA mutants with Pol II elongation activity partially restored the polyploidization. RNA-sequencing revealed that knockdown of EloA decelerated the transcription of genes enriched in the ERK1/2 cascade pathway. The phosphorylation activity of ERK1/2 decreased upon the EloA inhibition, and the polyploidization process of HEL was hindered when ERK1/2 phosphorylation was inhibited by PD0325901 or SCH772984. This study evidenced a positive role of EloA in HEL polyploidization upon PMA stimulation through enhanced ERK1/2 activity. [ABSTRACT FROM AUTHOR]

Inherited thrombocytopenia 2 (THC2) is difficult to diagnose due to the lack of specific clinical characteristics and diagnostic methods. To identify potential plasma protein biomarkers for THC2, we collected the plasma samples from a THC2 family (9 THC2 and 15 non-THC2 members), enriched the medium and low abundant proteins using Proteominer and analyzed the protein profiles using the liquid chromatography-mass spectrometry in data independent acquisition mode. Initially, we detected 784 proteins in the plasma samples of this family and identified 27 up-regulated and 36 down-regulated in the THC2 group compared to the non-THC2 group (|log2 ratio| >1 and p-value <0.05). To improve the predictive power, top eight dysregulated proteins (B7Z2B4, LTF, HP, ERN1, IGHV1-8, A0A0X9V9C4, VH6DJ, and D3JV41) were selected by an area under the curve-based random forest process to construct a clinical model. Multivariate analysis with random forest and support vector machine showed that the prediction model provided high discrimination ability for THC2 diagnosis (AUC: 1.000 and 0.967, respectively). The potential plasma protein biomarkers will be tested in more THC2 patients and other thrombocytopenia patients to further validate their specificity and sensitivity. [ABSTRACT FROM AUTHOR]

Thrombocytopenia 2 (THC2) is one of the most prevalent forms of inherited thrombocytopenia. It is caused by a heterogeneous group of ANKRD26 gene mutation and shows a heterogeneous clinical and laboratory characteristics. We present a big Chinese family with 10 THC2 patients carrying c.-128G > T heterozygous substitution in the 5-untranslated region of the ANKRD26 gene. Although the platelets are fewer than 50 × 109/L in 8 THC2 family members, only the proband and her son show a higher WHO bleeding score. The proband and her son are also beta-thalassemia carriers with heterozygous c.52A > T mutation of HBB , which might not be associated with the increased bleeding tendency since 3 other family members with low bleeding tendency also carried both ANKRD26 c.-128G > T and HBB c.52A > T mutations. However, the proband and her son also show hypofibrinogenaemia, which is likely the cause of their more severe clinical manifestation. HID1 c.442G > T mutation was detected not only in these two hypofibrinogenaemia family members but also in the other 8 family members with normal blood fibrinogen levels. Our study suggests that the co-occurrence of other inherited genetic conditions associated with blood coagulation might contribute to the heterogeneity of clinical and laboratory characteristics in THC2 patients. Considering the hematologic and myeloid malignancy predisposition of THC2 patients and a large population of immune thrombocytopenia in China, we urge more attention to be paid to the diagnosis of THC2 patients to avoid misdiagnosis and mistreatment. [ABSTRACT FROM AUTHOR]

Thrombocytopenia 2 (THC2) is a major type of inherited thrombocytopenia caused by the persistent ANKRD26 expression during the late stage of megakaryocytopoiesis. For the first time, we generated a human induced pluripotent stem cell (hiPSC) line SHAMUi001-A from the bone marrow hematopoietic progenitor cells of a THC2 patient, who has a heterozygous mutation (c.-128G>T) in the 5′-UTR of ANKRD26 gene. SHAMUi001-A cells retain the mutation, display pluripotent stem cell characteristics, and have a normal female karyotype. This disease-specific hiPSC line will be a useful model for THC2 research. [ABSTRACT FROM AUTHOR]