[Role of Histone Methylation in Myeloid Malignancies -Review].

Histone methylation is one of the important epigenetic regulatory mechanisms, and plays a significant role in a variety of physiological and pathological processes. Many recent studies have shown that abnormalities of histone methylation are closely related with the initiation and progression of myeloid malignancies. The reversibility of histone methylation provides a broad prospect for the discovery and application of specific small molecule drugs. This review summarizes the recent progresses in this area and mainly focuses on the correlation of histone methylation with myeloid malignancies.

[Establishment of Integration-Free Human Induced Pluripotent Stem Cells from A Patient with Primary Myelofibrosis].

OBJECTIVE: To establish the primary myelofibrosis (PMF)-induced pluripotent stem cell line (iPSC) by means of iPSC techinique so as to provide a experimental model for studying the blood disease mechanisms. METHODS: Induced pluripotent stem cells were generated from mononuclear cells isolated from a PMF patient with JAK2(V617F) mutation by using episomal vectors. RESULTS: PMF-derived iPSC was established from the patient with JAK2(V617F) gene mutation. The PMF-iPSC could be stably passaged, highly expressed pluripotent genes as human embryonic stem (ES) cells, and were able to form teratoma in NOD/SCID mice in vivo. H & E staining of the teratoma showed the presence of tissue type derived from all three embryonic germ layers. Sanger sequencing confirmed that PMF-derived iPSC carried different allele burdens of JAK2(V617F) gene mutation. CONCLUSION: The interation-free iPSC from primary myelofibrosis patient in vitro has been established. This PMF-derived iPSC line provides a valuable tool for studying the pathogenesis, screening of chimical drugs and realizing the standard therapy of PMF.

[Role of ASXL1 mutation in myeloid malignancies].

Additional sex comb-like 1 ( ASXL1) is an enhancer of Trithorax and Polycomb family, which are necessary for the maintenance of stable repression of homeotic and other loci. Recently, alterations of ASXL1 gene were identified in the hematopoietic cells from patients with a variety of myeloid malignancies, including chronic myelomonocytic leukemia (CMML, 43% of cases), myelodysplastic syndrome (MDS, 20%), myeloproliferative neoplasms (MPN, 10%) and acute myeloid leukemia (AML, 20%). The majority of ASXL1 mutations are frameshift and nonsense mutations. These clinical data suggest an important role of ASXL1 in the pathogenesis and/or transformation of myeloid malignancies. However, the role of ASXL1 in the pathogenesis of myeloid malignancies and in normal hematopoiesis in vivo, as well as the underlying mechanisms remains unknown. This article reviews the structure and function of ASXL1, the clinical characteristic and prognostic significance of ASXL1 mutation, the association of ASXL1 with other gene mutation, as well as ASXL1 knock-down or silence in vitro and in vivo models.

[Efficient isolation of mesenchymal stem cells from human bone marrow by direct plating method combined with modified primary explant culture].

Human bone marrow is the major source of mesenchymal stem cells (MSC). It was reported that the standard density gradient centrifugation method was not efficient in isolating MSC and it may be caused by the existing of bone marrow particles. In previous study, a lot of MSC were obtained by culturing bone marrow particles alone combined with standard method. However, it is time- and labor-consuming to obtain bone marrow particles by filtering and to isolate MNC by density gradient centrifugation. This study was purposed to explore the more simple and efficient method to isolate MSC from bone marrow. Seven normal bone marrow aspirates were collected and centrifugated. The bone marrow particles floated on surface layers were cultured by modified primary explant culture, whereas the bone marrow aspirates deposited were cultured by direct plating method, then the immun phenotype and differentiation capability of isolated cells were analyzed. The results showed that in 3 of 7 aspirates, bone marrow particles were floated on surface layers, whereas the other bone marrow cells and some particles were deposited after centrifugation. The MSC were reliably isolated from the floating layers or deposited aspirates by modified primary explant culture and direct plating method separately. After 3 passages the isolated MSC did not express CD45 and CD34, but expressed CD105, CD73, CD44, CD90, CD49e and they could differentiate into chondrocytes and adipocytes. It is concluded that normal human bone marrow MSC can be isolated simply and efficiently by direct plating method in combination with modified primary explant culture.