Idiopathic thrombocytopenic purpura (ITP) occurs more commonly in young women during the reproductive years. To obtain information for management of ITP in pregnancy, we performed a nationwide retrospective survey. Findings from a total of 284 pregnant women with ITP and their 286 newborn infants were available for analysis. The bleeding tendency at delivery was managed chiefly with corticosteroid, intravenous high-dose gamma-globulin, and platelet transfusion. Maternal complications occurred in 77 cases (27.1%) and were frequently seen in cases with poor control of ITP. Neonatal abnormalities, which were not influenced by the clinical state of the mother, occurred at a frequency of 17.8%. Thrombocytopenia in neonates occurred in 48 cases (22.4%), and bleeding tendency was found in 16 cases (6.3%) without severe bleeding. Prediction of thrombocytopenia in neonates was difficult. However, infants from splenectomized mothers with well-controlled ITP showed thrombocytopenia more frequently than those from nonsplenectomized mothers. Mothers treated with steroids at doses greater than 15 mg/day showed a high frequency of maternal complications and fetal abnormal body weight. These observations will be useful in the management of pregnant women with ITP and their infants.

A retrospective study was performed to determine the prevalence of Helicobacter pylori (H pylori) infection, the effect of H pylori eradication on platelet counts, and the characteristic clinical features of chronic immune or idiopathic thrombocytopenic purpura (ITP) with H pylori infection. H pylori infection was found in 300 patients, a group that was significantly older (P < .005) and had more cases of hyperplastic megakaryocytes in the bone marrow (P = .01) than patients without H pylori infection. H pylori eradication therapy was performed in 207 H pylori-positive ITP cases, and the platelet count response was observed in 63% of the successful eradication group and in 33% of the unsuccessful eradication group (P < .005). In the successful group, the complete remission and partial remission rates were 23% and 42%, respectively, 12 months after eradication. In the majority of responders, the platelet count response occurred 1 month after eradication therapy, and the increased platelet count continued without ITP treatment for more than 12 months. H pylori eradication therapy was effective even in refractory cases, which were unresponsive to splenectomy. In conclusion, H pylori infection was involved in most ITP patients older than 40 years in Japan, and eradication therapy should be the first line of treatment in H pylori-positive ITP patients.

Megakaryocytes and functional platelets were generated in vitro from murine embryonic stem (ES) cells with the use of a coculture system with stromal cells. Two morphologically distinctive megakaryocytes were observed sequentially. Small megakaryocytes rapidly produced proplatelets on day 8 of the differentiation, and large hyperploid megakaryocytes developed after day 12, suggesting primitive and definitive megakaryopoiesis. Two waves of platelet production were consistently observed in the culture medium. A larger number of platelets was produced in the second wave; 10 4 ES cells produced up to 10 8 platelets. By transmission electron microscopy, platelets from the first wave were relatively rounder with a limited number of granules, but platelets from the second wave were discoid shaped with well-developed granules that were indistinguishable from peripheral blood platelets. ES-derived platelets were functional since they bound fibrinogen, formed aggregates, expressed P-selectin upon stimulation, and fully spread on immobilized fibrinogen. These results show the potential utility of ES-derived platelets for clinical applications. Furthermore, production of gene-transferred platelets was achieved by differentiating ES cells that were transfected with genes of interest. Overexpression of the cytoplasmic domain of integrin ␤ 3 in the ESderived platelets prevented the activation of ␣ IIb ␤ 3 , demonstrating that this system will facilitate functional platelet studies. IntroductionVarious culture systems demonstrating megakaryocyte maturation and proplatelet formation from hematopoietic progenitor cells have been described. CD34 ϩ stem cells from various sources, including bone marrow, peripheral blood, and cord blood cells, have been successfully differentiated into megakaryocyte lineages in vitro. [1][2][3][4] Such culture systems include liquid culture or coculture systems with stromal cells, and most require the addition of a cytokine, thrombopoietin (TPO). 5,6 A few reports have also demonstrated platelet release into a culture medium. 4 Such methods have been used for studies of developmental biology of megakaryocytes or lineage-specific gene expression. Potential gains from these studies would be therapeutic applications, such as in transfusions or cell transplantation. However, the number of CD34 stem cells obtained and the difficulties in expansion of these cells in vitro are factors that limit such strategies from being able to generate sufficient amounts of megakaryocytes or platelets for clinical application or basic research.Embryonic stem (ES) cells are another good source, as these cells can rapidly proliferate and are able to differentiate to a variety of cell types. 7 Several techniques have been established to promote in vitro differentiation of murine ES cells to hematopoietic cell lineages, including megakaryocytes. In vitro differentiation has been performed by either formation of embryoid bodies, 8 coculture with stromal cell lines, 9,10 or culture on matrix-coated plates. 11 Differentiation...