Biosynthesis of FVIII in megakaryocytic cells: improved production and biochemical characterization

Methods for genetic modification of megakaryocytes and platelets

During recent decades there have been major advances in the fields of thrombosis and haemostasis, in part through development of powerful molecular and genetic technologies. Nevertheless, genetic modification of megakaryocytes and generation of mutant platelets in vitro remains a highly specialized area of research. Developments are hampered by the low frequency of megakaryocytes and their progenitors, a poor efficiency of transfection and a lack of understanding with regard to the mechanism by which megakaryocytes release platelets. Current methods used in the generation of genetically modified megakaryocytes and platelets include mutant mouse models, cell line studies and use of viruses to transform primary megakaryocytes or haematopoietic precursor cells. This review summarizes the advantages, limitations and technical challenges of such methods, with a particular focus on recent successes and advances in this rapidly progressing field including the potential for use in gene therapy for treatment of patients with platelet disorders.

The treatment of hemophilia A: from protein replacement to AAV-mediated gene therapy

Factor VIII (FVIII) is an essential component in blood coagulation, a deficiency of which causes the serious bleeding disorder hemophilia A. Recently, with the development of purification level and recombinant techniques, protein replacement treatment to hemophiliacs is relatively safe and can prolong their life expectancy. However, because of the possibility of unknown contaminants in plasma-derived FVIII and recombinant FVIII, and high cost for hemophiliacs to use these products, gene therapy for hemophilia A is an attractive alternative to protein replacement therapy. Thus far, the adeno-associated virus (AAV) is a promising vector for gene therapy. Further improvement of the virus for clinical application depends on better understanding of the molecular structure and fate of the vector genome. It is likely that hemophilia will be the first genetic disease to be cured by somatic cell gene therapy.

Study on the efficacy and safety of Xueyou Mixture in treating hemophilia

OBJECTIVE

To observe the effect of Xueyou Mixture (, XYM) on blood coagulation factors and its safety in treating hemophilia.

METHODS

To the randomly selected 65 inpatients of hemophilia, XYM was administered accompanied with intravenous dripping of liver cell growth factor 60-100 mg once a day to protect the liver, with no blood products like concentrated VIII and FIX factors or blood plasma given. The treatment lasted for 3 weeks. The short-term efficacy and adverse reactions were observed. The long-term efficacy in patients was observed in a follow-up study of 6-12 months after they were discharged from the hospital but continuously took XYM orally.

RESULTS

The short-term markedly effective rate in the patients was 95.38% (62/65). After they were treated for 3 weeks, the level of FVIII factor activity increased in 56 patients of type A from (3.32+/-2.21) % to (4.18+/-2.23) %, and in 9 of type B from (4.92+/-1.81) % to (5.64+/-1.96) %. Compared with that before treatment, the difference was significant in both of them (P<0.01). No obvious adverse reaction was found in the treatment period. The follow-up study showed that in 22 patients of type A, the FVIII factor activity ratio increased from (3.25+/-2.11) % to (6.31+/-2.16) %, (8.36+/-1.05) %, and (16.38+/-2.71) % in the 2nd, 3rd and 6th month after discharge respectively, all showing significant difference to that before treatment (P<0.01); and in 4 patients of type B, it increased from (4.15+/-2.26) % to 7.8% and 11.6% (mean value) in the 2nd and 6th month respectively.

CONCLUSION

XYM could raise the activity of factors VIII and IX in patients with hemophilia, and the degree of the rise is related with the duration of the therapy, with no obvious adverse reaction, which strikes out a new path and new train of thinking for the treatment of the disease by nonblood preparation.