Non-myeloablative allogeneic hematopoietic stem cell transplantation has been extensively applied in patients with hematologic malignancies who are ineligible for conventional hematopoietic stem cell transplantation because of age or medical comorbidities. Non-myeloablative regimens lead to an initial state of mixed hematopoietic chimerism which can produce a marked effect of graft versus tumor to treat the diseases. Compared with the conventional hematopoietic stem cell transplantation, non-myeloablative allogeneic hematopoietic stem cell transplantation has a lower transplant-related mortality and incidence rate of graft-versus-host disease. The improvement of non-myeloablative regimens and the prophylaxis of diseases associated with transplantation can improve the therapeutic efficacy. Though many therapies have been introduced and proved to be successful in animal models, we still need to investigate the research trend and the problem on human body.

The myelodysplastic syndromes (MDS) are a group of clonal disorders of the hematopoietic stem/progenitor cells characterized by the presence of ineffective hematopoiesis and an increased risk of transformation to acute myeloid leukemia (AML).In the 54th ASH annual meeting,lots of new discoveries about the molecular mechanisms (such as mutations in ASXL1 and Dido1) behind MDS and the relationship between the mechanisms and the clinical outcomes were introduced.On therapy,novel agents based on the molecular mechanisms occured extending survival.Haematopoietic stem cell transplantation (HSCT) remains the only curative therapy,there' re also many developments in HSCT reported in the meeting.

Allogeneic peripheral blood stem cells transplantation is the most effective method for maligant hematological disease. The author reviewed the indication of acceptance of HLA mismatch kinds and the prediction of the results by selecting the measures such as pretreatment,mobilization,stem cells disposal,immunity reconstruction,graft failure management in order to improve the engraft rate.

ABCG2 is a member of the ATP-binding cassette (ABC) transporter family.The overexpression of ABCG2 is identified as one of the important mechanisms that limiting cellular accumulation of various compounds.With regard to its broad substrate spectrum including various anticancer drugs and environmental carcinogens,the function of ABCG2 is associated with multidrug resistance (MDR) and tumor development.ABCG2 as a target site to reverse MDR has been widely concered.

Progress toward improving management of myelodysplastic syndromes (MDS) occurred every year.This review focused on the new developments of classification,diagnoses,prognostic stratification and therapy on MDS in recent five years.In addiction,a brief introduction of pediatric MDS was presented here.All this were for a better exploration in the future.

The myelodysplastic syndromes (MDS),which are characterized by the presence of ineffective hematopoiesis and an increased risk of transformation to acute myeloid leukemia (AML),are a group of clonal disorders deriving from damage of the hematopoietic stem/progenitor cells.In the 56th American Society of Hematology (ASH) annual meeting,lots of new discoveries about the pathogenesis of MDS and the role of the pathogenesis in the clinical outcomes and treatment were introduced.There were also many developments in the treatment of MDS including drug therapies and Hematopoietic stem cell tranplantation (HSCT) reported in the meeting.

Viral infections remain a major cause of morbidity in patients with immunodeficiency,such as recipients of hematopoietic stem cell transplantation (HSCT).Adoptive transfer of donor-derived virusspecific cytotoxic T lymphocytes is a strategy to restore virus-specific immunity to prevent or treat viral diseases and has been tested in the clinical setting for more than 20 years.The 55th ASH annual meeting reported lots of basic and clinical experience about CTL and summarized lots of trails to evaluate it,which will give us some new thought about the antivirus therapy after HSCT.

Multidrug resistance gene MDR1 C3435T polymorphism influences tumor incidence and treatment outcome. Carcinogenic substances are easier to accumulate in tissue for T allele patients, so TT genotype patients are more likely to develop into breast neoplasms, stomach neoplasms and colorectal neoplasms.Besides, the chemotherapy treatment outcome for patients with both C3435T TT genotype and wild-type KRAS is the best. However, due to ethnic, regional and sample differences, the relationship between C3435T polymorphism and stomach neoplasms 、colorectal neoplasms is still unclear.

The myelodysplastic syndromes (MDS), which are characterized by the presence of ineffective hematopoiesis and an increased risk of transformation into acute myeloid leukemia (AML), are a group of clonal disorders deriving from damage of the hematopoietic stem/progenitor cells. Researches in the past few years have still highly recommended the pathogenesis,clinical new agents and combination therapy, immunotherapy and hematopoietic stem cell transplantation of the MDS. This article will introduce several highlights of MDS combined with the relevant reports in the 57th American Society of Hematology annual meeting.

Objective: To evaluate the effectiveness of random mutagenesis via mutator E.coli strain and error prone PCR. Methods: A ScFv containing phagemid was transformed into mutator strain XL1 Red and subjected to 7 overnight growth phases with 1/100 dilution of each phase. DNA was extracted and sequenced. The ScFv gene was also subjected to PCR mutagenesis. Mutation effects of Mg 2+ concentration, alteration of individual dNTP amounts and addition of dITP were investigated. Results: The mutation rate of 7 growth phases (about 50 cell cycles) in XL1 Red was less than 0.1%. In error prone PCR, higher concentration of Mg 2+ increased the mutation rate. Increased content of dTTP and dCTP had better effect than that of dATP and dGTP. Addition of dITP plus low concentration dATP or dGTP caused lower mutation rate. More than 2% mutation could be reached by 2 rounds PCR containing 5 mmol/L MgCl 2, 0.5 mmol/L MnCl 2, 1 mmol/L dTTP and 1 mmol/L dCTP. But the mutation showed obvious base bias with most substitutions at A/T positions and a prevalence of transition over transversion. Conclusion: Random mutagenesis in mutator strain has too low mutation rate for antibody affinity maturation. A more than 2% mutation rate can be obtained by error prone PCR, which is suitable for constructing mutated antibody libraries, but the base bias of error prone PCR should be considered.