No abstract

Hepatic tumors, exhibiting mature hepatocytes and undifferentiated cells merging with cholangiocyte and hepatocyte phenotypes, are frequently described. The mechanisms by which they occur remain unclear. We report differentiation and transdifferentiation behaviors of human HepaRG cells isolated from a differentiated tumor developed consecutively to chronic HCV infection. We demonstrate that, in vitro, proliferating HepaRG cells differentiate toward hepatocyte-like and biliary-like cells at confluence. If hepatocyte-like cells are selectively isolated and cultured at high cell density, they proliferate and preserve their differentiation status. However, when plated at low density, they transdifferentiate into hepatocytic and biliary lineages through a bipotent progenitor. In accordance, transplantation of either undifferentiated or differentiated HepaRG cells in uPA/SCID mouse damaged liver gives rise mainly to functional human hepatocytes infiltrating mouse parenchyma. Analysis of the differentiation/transdifferentiation process reveals that: (1) H epatic tumors with combined hepatocellular cholangiocarcinoma have been frequently described for instance, hepatoblastoma with cholangioblastic features in young patients 1 and HCCs with dual expression of hepatocyte and bile duct markers in adult patients suffering from diseases related to HCV and/or HBV infection. 2 Such tumors usually contain mature hepatocytes and so-called transitional areas that consist of undifferentiated cells that have morphological and immunological features of both hepatocytes and cholangiocytes. 3 Co-expression of hepatocytic and biliary markers suggests involvement of hepatic progenitor cells in development of these human tumors and supports the concept of genetic events to explain their abnormal growth during tumor formation. 4 However, mechanisms of occurrence of these progenitors and abnormal control of their expansion and differentiation are still unclear.Hepatic progenitor cells, also referred to as oval cells in rodents, have been defined as immature epithelial cells able to differentiate toward both biliary and hepatocytic lineages. The smallest ramification of the biliary tree in adult liver, the canal of Hering, may constitute the niche for these hepatic progenitor cells. 5 They are few in number, and because bile ductular and hepatocytic cells have a tremendous capacity to proliferate and differentiate, heAbbreviations: BrdU, bromodeoxyuridine; HNF, hepatocyte nuclear factor; RT, reverse transcription.

Background Patients with hematological malignancies (HM) are at high risk of mortality from SARS-CoV-2 disease 2019 (COVID-19). A better understanding of risk factors for adverse outcomes may improve clinical management in these patients. We therefore studied baseline characteristics of HM patients developing COVID-19 and analyzed predictors of mortality. Methods The survey was supported by the Scientific Working Group Infection in Hematology of the European Hematology Association (EHA). Eligible for the analysis were adult patients with HM and laboratory-confirmed COVID-19 observed between March and December 2020. Results The study sample includes 3801 cases, represented by lymphoproliferative (mainly non-Hodgkin lymphoma n = 1084, myeloma n = 684 and chronic lymphoid leukemia n = 474) and myeloproliferative malignancies (mainly acute myeloid leukemia n = 497 and myelodysplastic syndromes n = 279). Severe/critical COVID-19 was observed in 63.8% of patients (n = 2425). Overall, 2778 (73.1%) of the patients were hospitalized, 689 (18.1%) of whom were admitted to intensive care units (ICUs). Overall, 1185 patients (31.2%) died. The primary cause of death was COVID-19 in 688 patients (58.1%), HM in 173 patients (14.6%), and a combination of both COVID-19 and progressing HM in 155 patients (13.1%). Highest mortality was observed in acute myeloid leukemia (199/497, 40%) and myelodysplastic syndromes (118/279, 42.3%). The mortality rate significantly decreased between the first COVID-19 wave (March–May 2020) and the second wave (October–December 2020) (581/1427, 40.7% vs. 439/1773, 24.8%, p value < 0.0001). In the multivariable analysis, age, active malignancy, chronic cardiac disease, liver disease, renal impairment, smoking history, and ICU stay correlated with mortality. Acute myeloid leukemia was a higher mortality risk than lymphoproliferative diseases. Conclusions This survey confirms that COVID-19 patients with HM are at high risk of lethal complications. However, improved COVID-19 prevention has reduced mortality despite an increase in the number of reported cases.

EDITORthat, since then, it has frequently been suggested that higher doses of LMWH be given to Covid-19 patients to prevent venous thromboembolism. However, there is no demonstration that standard prophylactic doses are insufficient to prevent it. Pulmonary vessel occlusions that are observed in severe Covid-19 patients are caused by pulmonary thrombi, whose pathogenesis is unclear but likely to be associated with the severe pulmonary inflammation.Concerning the type of heparin, we cannot be certain that one type is better than the other; in other words, it is difficult to say UFH is better than LMWH. LMWH was chosen in the guidance because of the ease of use, no need for laboratory monitoring, and familiarity among the spectrum of doctors with varying experience. The question of whether therapeutic doses of either UFH or LMWH should be considered for all patients is currently unknown and the authors would currently reserve such a dose for those who have confirmed thrombosis including filter thrombosis. We are aware however that therapeutic dose is being administered in some centers where there is very high suspicion of pulmonary embolism and imaging is impractical. Although these approaches are reasonable, we stress that these approaches are undertaken in a trial setting.

The role of lymphocyte apoptosis in septic shock remains a controversial issue. Using Annexin V and flow cytometry analysis on freshly isolated cells, we evaluated circulating lymphocyte apoptosis in 23 septic shock, 25 sepsis without shock, 7 nonseptic critically ill, and 25 control patients. In patients with sepsis, we compared day 1 lymphocyte apoptosis (i.e., within 3 days of the onset of infection) with that observed 5-7 days after (day 6) according to shock state, mortality, and seventy factors. At day 1, patients in septic shock exhibited higher lymphocyte apoptosis than that present in controls (16.5% +/- 3.5% vs. 3% +/- 0.5%, respectively, P = 0.0001). At day 6, patients with sepsis without shock restored undamaged CD4+ T and CD8+ T lymphocyte counts, whereas patients in septic shock increased only CD4+ T cells. Similarly, survivors restored undamaged lymphocyte count at day 6 (+70%, P < 0.001), whereas nonsurvivors did not. Day 6 undamaged lymphocyte count negatively correlated with day 1 SAPS II, day 6 LOD score, mechanical ventilation, and ICU stay duration. We observed no apoptotic effect of septic shock plasma or septic shock circulating mononuclear cells on target lymphoid cell lines. We found no alteration in any death receptors Fas, TRAIL-R1, TRAIL-R2, or in their ligands on circulating blood cells. Catecholamines and interleukin 10 levels significantly increased in patients with septic shock, but did not correlate with apoptosis levels. We conclude that lymphocyte apoptosis is rapidly increased in blood of patients in septic shock and that lymphocyte apoptosis leads to a profound and persistent lymphopenia associated with poor outcome. These results suggest that lymphocyte apoptosis is one of the main components of human septic shock immune dysfunction and could be related more to microcirculatory disturbance than to circulating factors.