Humanized mouse models for inherited thrombocytopenia studies.

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.

Platelet-promoting drug delivery efficiency for inhibition of tumor growth, metastasis, and recurrence.

Nanomedicines are considered one of the promising strategies for anticancer therapy; however, the low targeting efficiency of nanomedicines in vivo is a great obstacle to their clinical applications. Camouflaging nanomedicines with either platelet membrane (PM) or platelet would significantly prolong the retention time of nanomedicines in the bloodstream, enhance the targeting ability of nanomedicines to tumor cells, and reduce the off-target effect of nanomedicines in major organs during the anticancer treatment. In the current review, the advantages of using PM or platelet as smart carriers for delivering nanomedicines to inhibit tumor growth, metastasis, and recurrence were summarized. The opportunities and challenges of this camouflaging strategy for anticancer treatment were also discussed.

Platelet detection as a new liquid biopsy tool for human cancers.

Cancer is still a leading cause of death worldwide and liquid biopsy is a powerful tool that can be applied to different stages of cancer screening and treatment. However, as the second most abundant cell type in the bloodstream, platelets are isolated through well-established and fast methods in clinic but their value as a BioSource of cancer biomarkers is relatively recent. Many studies demonstrated the bidirectional interaction between cancer cells and platelets. Platelets transfer various proteins (e.g., growth factors, cytokine, chemokines) and RNAs (e.g., mRNA, lncRNA, miRNA, circRNA) into the tumor cells and microenvironment, leading the stimulation of tumor growth and metastasis. In turn, the platelet clinical characteristics (e.g., count and volume) and contents (e.g., RNA and protein) are altered by the interactions with cancer cells and this enables the early cancer detection using these features of platelets. In addition, platelet-derived microparticles also demonstrate the prediction power of being cancer biomarkers. In this review, we focus on the clinical applications of platelet detection using the platelet count, mean platelet volume, platelet RNA and protein profiles for human cancers and discuss the gap in bringing these implementations into the clinic.

EloA promotes HEL polyploidization upon PMA stimulation through enhanced ERK1/2 activity.

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.

Generation of the human induced pluripotent stem cell line (SHAMUi001-A) carrying the heterozygous c.-128G>T mutation in the 5'-UTR of the ANKRD26 gene.

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.

A Rare Big Chinese Family With Thrombocytopenia 2: A Case Report and Literature Review.

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.

Potential target-related proteins in rabbit platelets treated with active monomers dehydrocorydaline and canadine from Rhizoma corydalis.

BACKGROUND: Dehydrocorydaline (DHC) and canadine (THB) are two active alkaloid compounds in Corydalis yanhusuo (Y.H. Chou & Chun C. Hsu) W.T. Wang ex Z.Y. Su & C.Y. Wu (Papaveraceae) (Rhizoma Corydalis). DHC and THC were previously shown to exert anti-platelet aggregation effect dose-dependently, but their exact mechanisms had not yet been addressed. Therefore, it is essential to study the mechanisms of DHC and THB affecting on platelet's function. PURPOSE: To investigate the anti-platelet effects and corresponding signal cascades of DHC and THB on platelet aggregation. METHODS: Firstly, in vitro anti-platelet aggregation of DHC and THB induced by different agonists including thrombin (THR), adenosine diphosphate (ADP) and arachidonic acid (AA) were determined through turbidimetry method. Then the possible target-related platelet proteins after treated with DHC/THB were separated and identified by two dimensional gel electrophoresis (2-DE) and MALDI-TOF-MS/MS analysis, respectively. Finally, the signal cascades network induced by DHC/THB were predicted through functional analysis of these proteins along with the determination of platelet DAG concentration. RESULTS: The platelet aggregation stimulated by THR, ADP and AA were inhibited by DHC and THB dose-dependently to a certain degree. Meanwhile, DHC and THB had the strongest effect on ADP- and THR-induced platelet aggregation respectively. In addition, treatment of these two compounds caused regulations of about sixty proteins in platelet, including cytoskeleton proteins, cell signaling proteins, proteins related to material energy metabolism, etc. CONCLUSIONS: Using proteomic analysis combined with platelet aggregation test and ELISA, this study was successful in exploring the possible mechanisms of DHC/THB on platelet aggregation. DHC might inhibit platelet aggregation by a mechanism involving the ADP receptors P2Y1 and P2Y12, and the effect of THB on platelet function may be related to its binding to THR receptor PAR1 for mediated Gi signaling pathway. These results provide fundamental information for the anti-thrombotic effect of RC.