Megakaryocytes associate with the bone marrow vasculature where they convert their cytoplasm into proplatelets that protrude through the vascular endothelium into the lumen and release platelets. The ...extracellular matrix (ECM) microenvironment plays a critical role in regulating these processes. In this work we demonstrate that, among bone marrow ECM components, fibronectin, type IV collagen, and laminin are the most abundant around bone marrow sinusoids and constitute a pericellular matrix surrounding megakaryocytes. Most importantly, we report, for the first time, that megakaryocytes express components of the basement membrane and that these molecules contribute to the regulation of megakaryocyte development and bone marrow ECM homeostasis both in vitro and in vivo. In vitro, fibronectin induced a threefold increase in the proliferation rate of mouse hematopoietic stem cells leading to higher megakaryocyte output with respect to cells treated only with thrombopoietin or other matrices. However, megakaryocyte ploidy level in fibronectin‐treated cultures was significantly reduced. Stimulation with type IV collagen resulted in a 1.4‐fold increase in megakaryocyte output, while all tested matrices supported proplatelet formation to a similar extent in megakaryocytes derived from fetal liver progenitor cells. In vivo, megakaryocyte expression of fibronectin and basement membrane components was upregulated during bone marrow reconstitution upon 5‐fluorouracil induced myelosuppression, while only type IV collagen resulted upregulated upon induced thrombocytopenia. In conclusion, this work demonstrates that ECM components impact megakaryocyte behavior differently during their differentiation and highlights a new role for megakaryocyte as ECM‐producing cells for the establishment of cell niches during bone marrow regeneration. Stem Cells 2014;32:926–937
Background
Although many trials are currently investigating the safety and efficacy of convalescent plasma (CP) in critically ill COVID‐19 patients, there is a paucity of ongoing and published ...studies evaluating the CP donors' side. This retrospective study reports the first Italian experience on CP donors' selection and donations.
Methods
Patients aged 18‐68 years who had recovered from COVID‐19 at least 2 weeks previously were recruited between March 18 and June 30, 2020 in a study protocol at the Italian hospitals of Pavia and Mantova.
Results
During the study period, 494 of 512 donors recruited were judged eligible and underwent 504 plasmapheresis procedures. Eighty‐five percent (437/512) of the CP donors were males. The average time between symptom recovery and CP donation was 36.6 (±20.0) days. Four hundred and eighty‐eight plasmapheresis procedures (96.8%) were concluded and each unit was divided into two subunits (total 976) with an average volume of 316.2 (±22.7) mL. Ninety‐three percent (460/494) of CP donors at the time of plasma donation had a neutralizing IgG titer ≥1:80. Plasmapheresis‐related adverse reactions occurred in 2.6% (13/504) of cases; all the reactions were mild and none required therapeutic intervention. Donors' age and COVID‐19 severity were positively associated with greater antibody responses.
Conclusion
This study demonstrates the feasibility and safety of a pilot CP program conducted in Italy. The identification of factors (ie, age and severity of COVID‐19) positively associated with higher neutralizing antibody titers at the time of donation may help to optimize the selection of CP donors.
The paracrine properties of human amniotic membrane‐derived mesenchymal stromal cells (hAMCs) have not been fully elucidated. The goal of the present study was to elucidate whether hAMCs can exert ...beneficial paracrine effects on infarcted rat hearts, in particular through cardioprotection and angiogenesis. Moreover, we aimed to identify the putative active paracrine mediators. hAMCs were isolated, expanded, and characterized. In vitro, conditioned medium from hAMC (hAMC‐CM) exhibited cytoprotective and proangiogenic properties. In vivo, injection of hAMC‐CM into infarcted rat hearts limited the infarct size, reduced cardiomyocyte apoptosis and ventricular remodeling, and strongly promoted capillary formation at the infarct border zone. Gene array analysis led to the identification of 32 genes encoding for the secreted factors overexpressed by hAMCs. Among these, midkine and secreted protein acidic and rich in cysteine were also upregulated at the protein level. Furthermore, high amounts of several proangiogenic factors were detected in hAMC‐CM by cytokine array. Our results strongly support the concept that the administration of hAMC‐CM favors the repair process after acute myocardial infarction.
The goal of this study was to elucidate whether human amniotic membrane‐derived mesenchymal stromal cells (hAMCs) can exert beneficial paracrine effects on infarcted rat hearts. In particular, the administration of hAMC‐conditioned medium repaired ischemic damage through cardioprotection and angiogenesis. Finally, several putative active paracrine mediators that might account for the effects observed were identified by gene and protein arrays.
CLAD (Chronic Lung Allograft Dysfunction) remains a serious complication following lung transplantation. Some evidence shows that portions of Extracorporeal Photopheresis (ECP)-treated patients ...improve/stabilize their graft function. In spite of that, data concerning molecular mechanisms are still lacking. Aims of our study were to assess whether ECP effects are mediated by Mononuclear Cells (MNCs) modulation in term of microRNAs (miRNAs) expression and growth factors release.
Cells from leukapheresis of 16 CLAD patients, at time 0 and 6-months (10 cycles), were cultured for 48h ± PHA (10 ug/ml) or LPS (2 ug/ml). Expression levels of miR-146a-5p, miR-155-5p, miR-31-5p, miR181a-5p, miR-142-3p, miR-16-5p and miR-23b-5p in MNCs-exosomes were evaluated by qRT-PCR, while ELISA assessed different growth factors levels on culture supernatants.
Our result showed miR-142-3p down-regulation (p = 0.02) in MNCs of ECP-patients after the 10 cycles and after LPS stimulation (p = 0.005). We also find miR-146a-5p up-regulation in cells after the 10 cycles stimulated with LPS (p = 0.03). Connective tissue growth factor (CTGF) levels significantly decreased in MNCs supernatant (p = 0.04). The effect of ECP is translated into frequency changes of Dendritic Cell (DC) subpopulations and a slight increase in T regulatory cells (Treg) number and a significant decrease in CTGF release.
ECP might affect regulatory T cell functions, since both miR-142 and miR-146a have been shown to be involved in the regulation of suppressor regulatory T cell functions and DCs. On the other side ECP, possibly by regulating macrophage activation, is able to significantly down modulate CTGF release.
BACKGROUND: Extracorporeal photochemotherapy (ECP) is a valid therapeutic option in the treatment of acute and chronic graft‐versus‐host disease (aGVHD and cGVHD, respectively). No standard clinical ...and laboratory criteria of response to ECP treatment are available at the moment.
STUDY DESIGN AND METHODS: Clinical and laboratory variables on 73 pediatric patients with aGVHD (n = 50) and cGVHD (n = 23) were correlated with response to ECP and survival.
RESULTS: An overall response (OR) was obtained in 34 of 50 (68%) aGVHD and in 16 of 23 (69.5%) cGVHD patients. Steroid tapering within 30 days of 1.3 mg/kg in OR (p = 0.004) was the sole highly significant correlation with response found in aGVHD while no correlation emerged for cGVHD (p = 0.28). Among aGVHD patients, response to ECP was inversely associated with death: among OR, deaths were 13 of 34 (38.2%), while among nonresponders, deaths were 15 of 16 (93.8%; p < 0.001). On the other hand, decrease of steroid dose at 30 days was associated with survival: for each 1 mg/kg reduction, the hazard ratio was 2.2, and the 95% confidence interval was 1.5 to 3.2 (p < 0.001). No other clinical or laboratory variables statistically associated with survival were found.
CONCLUSIONS: Our results demonstrate that steroid tapering within the first 30 days of ECP treatment in aGVHD and response to ECP in acute and chronic GVHD are the only variables influencing response and survival, respectively.
In the WHO diagnostic classification, prefibrotic myelofibrosis (pre-MF) is included in the category of primary myelofibrosis (PMF). However, strong evidence for this position is lacking.
We ...investigated whether pre-MF may be aligned along a clinical and biological continuum in 683 consecutive patients who received a WHO diagnosis of PMF.
As compared with PMF-fibrotic type, pre-MF (132 cases) showed female dominance, younger age, higher hemoglobin, higher platelet count, lower white blood cell count, smaller spleen index and higher incidence of splanchnic vein thrombosis. Female to male ratio and hemoglobin steadily decreased, while age increased from pre-MF to PMF- fibrotic type with early and to advanced bone marrow (BM) fibrosis. Likely, circulating CD34+ cells, LDH levels, and frequency of chromosomal abnormalities increased, while CXCR4 expression on CD34+ cells and serum cholesterol decreased along the continuum of BM fibrosis. Median survival of the entire cohort of PMF cases was 21 years. Ninety-eight, eighty-one and fifty-six percent of patients with pre-MF, PMF-fibrotic type with early and with advanced BM fibrosis, respectively, were alive at 10 years from diagnosis.
Pre-MF is a presentation mode of PMF with a very indolent phenotype. The major consequences of this contention is a new clinical vision of PMF, and the need to improve prognosis prediction of the disease.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Few investigators have evaluated the usefulness of the JAK2 V617F mutation for explaining the phenotypic variations and for predicting the risk of major clinical events in primary myelofibrosis ...(PMF). In a transversal survey we assayed by allele-specific polymerase chain reaction (PCR) the JAK2 V617F mutational status in 304 patients with PMF. Multiple DNA samples were collected prospectively from 64 patients, and a highly sensitive quantitative PCR was used as a confirmatory test. In a longitudinal prospective study we determined the progression rate to clinically relevant outcomes in 174 patients who had JAK2 mutation determined at diagnosis. JAK2 V617F was identified in 63.4% of patients. None of the V617F-negative patients who were sequentially genotyped progressed to become V617F positive, whereas progression rate from heterozygous to homozygous mutation was 10 per 100 patient-years. JAK2 V617F mutation contributed to hemoglobin, aquagenic pruritus, and platelet count variability, whereas homozygous mutation was independently associated with higher white blood cell count, larger spleen size, and greater need for cytoreductive therapies. Adjusting for conventional risk factors, V617F mutation independently predicted the evolution toward large splenomegaly, need of splenectomy, and leukemic transformation. We conclude that JAK2 V617F genotype should be considered in any future risk stratification of patients with PMF.
Background
Endothelial progenitor cells (EPCs) have been shown to increase during physiological pregnancy and are believed to play a fundamental role in the process of placentation. Reduced levels of ...EPCs during pregnancy have been associated with preeclampsia and miscarriage. Women with multiple sclerosis (MS) are not at increased risk of preeclampsia nor of general adverse obstetric outcome, in contrast with some other autoimmune diseases.
Objective
The aim of this study was to evaluate circulating EPCs levels in pregnant patients with MS.
Methods
CD34+ and CD133+ were longitudinally detected by flow cytometry in the maternal plasma of 29 healthy controls and 9 MS patients and in the cord blood of their newborns.
Results
EPCs were affected by pregnancy with the same trend in both groups (CD34+
p
= 0.0342; CD133+
p
= 0.0347). EPCs during pregnancy were increased in MS (mean ± SD: CD34+ cells 0.038 ± 0.010; CD133+ 0.024 ± 0.009) with respect to healthy controls (mean ± SD: CD34+ cells 0.022 ± 0.006; CD133+ 0.016 ± 0.004), CD34+
p
= 0.0004; CD133+
p
= 0.0109. EPCs levels of the cord blood of MS patients' newborns mild correlated with maternal EPC levels at delivery (CD34+: spearman’s Rho 0.658,
p
= 0.054; CD133+: spearman’s Rho 0.758,
p
= 0.018).
Conclusions
This work identified increased circulating EPC levels during pregnancy, following the same trend both in MS patients and healthy controls. Despite the similar trend, the levels of circulating EPCs were significantly higher in MS patients with respect to the control population. A correlation was also found in MS patients between cord blood EPCs and circulating EPCs at delivery.
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