Long-Term SARS-CoV-2 Antibody Seroprevalence in Blood Donors, Italy.

We evaluated SARS-CoV-2 antibody response in voluntary blood donors in Italy at different timepoints. Immediately after lockdown easing, 908/25,657 donors (3.5%) had low IgG titers against nucleocapsid. In the next 2 years, titers increased despite few COVID-19 symptoms. On multivariate analysis, allergic rhinitis was associated with reduced risk for symptomatic COVID-19.

Impact of soluble tumor necrosis factor-related apoptosis-inducing ligand released by engineered adipose mesenchymal stromal cells on white blood cells.

BACKGROUND AIMS: The proapoptotic protein tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is physiologically expressed by immune cells and performs regulatory functions in infections, autoimmune diseases and cancer, where it acts as a tumor suppressor. Adipose-derived mesenchymal stromal cells (AD-MSCs) also may play immunomodulatory roles in both primary and acquired immune responses. We have previously demonstrated the efficacy of an anticancer gene therapy based on AD-MSC engineered to secrete a soluble TRAIL variant (sTRAIL) against pancreatic cancer. However, the impact of AD-MSC sTRAIL on leukocyte subsets has been not yet considered also to predict a possible immunotoxicity profile in the clinical translation of this cell-based anticancer strategy. METHODS: Monocytes, polymorphonuclear cells and T lymphocytes were freshly isolated from the peripheral blood of healthy donors. Immunophenotype and functional (DR4 and DR5) and decoy (DcR1 and DcR2) TRAIL receptors were tested by flow cytometry. The viability of white blood cells treated with sTRAIL released by gene-modified AD-MSC or co-cultured with AD-MSC sTRAIL was then evaluated by both metabolic assays and flow cytometry. In addition, cytokine profile in co-cultures was analyzed by multiplex enzyme-linked immunosorbent assay. RESULTS: Monocytes and polymorphonuclear cells showed high positivity for DR5 and DcR2, respectively, whereas T cells revealed negligible expression of all TRAIL receptors. Irrespective of TRAIL receptors' presence on the cell membrane, white blood cells were refractory to the proapoptotic effect displayed by sTRAIL secreted by gene-modified AD-MSC, and direct cell-to-cell contact with AD-MSC sTRAIL had negligible impact on T-cell and monocyte viability. Cytokine crosstalk involving interleukin 10, tumor necrosis factor alpha, and interferon gamma secreted by T lymphocytes and vascular endothelial growth factor A and interleukin 6 released by AD-MSC was highlighted in T-cell and AD-MSC sTRAIL co-cultures. CONCLUSIONS: In summary, this study demonstrates the immunological safety and thus the clinical feasibility of an anticancer approach based on AD-MSC expressing the proapoptotic molecule sTRAIL.

Valproic acid triggers erythro/megakaryocyte lineage decision through induction of GFI1B and MLLT3 expression.

Histone deacetylase inhibitors represent a family of targeted anticancer compounds that are widely used against hematological malignancies. So far little is known about their effects on normal myelopoiesis. Therefore, in order to investigate the effect of histone deacetylase inhibitors on the myeloid commitment of hematopoietic stem/progenitor cells, we treated CD34(+) cells with valproic acid (VPA). Our results demonstrate that VPA treatment induces H4 histone acetylation and hampers cell cycle progression in CD34(+) cells sustaining high levels of CD34 protein expression. In addition, our data show that VPA treatment promotes erythrocyte and megakaryocyte differentiation. In fact, we demonstrate that VPA treatment is able to induce the expression of growth factor-independent protein 1B (GFI1B) and of mixed-lineage leukemia translocated to chromosome 3 protein (MLLT3), which are crucial regulators of erythrocyte and megakaryocyte differentiation, and that the up-regulation of these genes is mediated by the histone hyperacetylation at their promoter sites. Finally, we show that GFI1B inhibition impairs erythroid and megakaryocyte differentiation induced by VPA, while MLLT3 silencing inhibits megakaryocyte commitment only. As a whole, our data suggest that VPA sustains the expression of stemness-related markers in hematopoietic stem/progenitor cells and is able to interfere with hematopoietic lineage commitment by enhancing erythrocyte and megakaryocyte differentiation and by inhibiting the granulocyte and mono-macrophage maturation.

Morphologic, histochemical, and functional analysis of platelet-rich plasma activity on skeletal cultured cells.

BACKGROUND: Platelet-rich plasma (PRP) is a medium containing concentrated amounts of growth factors in a form that is easy to handle in regenerative sites. The aim of this study was to assess the effect of PRP on the differentiation of cultured skeletal cells and the capability of PRP to induce the production of some osteogenesis-related molecules and mineralization. STUDY DESIGN AND METHODS: Flow cytometry (cellular antigens), real-time quantitative polymerase chain reaction (RT-qPCR; bone morphogenetic protein [BMP] messengers), alkaline phosphatase (ALP; osteogenic expression), and calcification analyses were performed on 24- and 48-hour human bone cells (HBCs) and 143B and SaOS-2 (osteosarcoma) cell cultures to study the effect of PRP on proliferation and differentiation of skeletal cultured cells. PRP was added using different protocols since no studies are available on bone cultures treated in the long term with PRP. RESULTS: Flow cytometry showed PRP induction toward a nonhemopoietic lineage in HBCs; RT-qPCR showed enhanced mRNA encoding for BMP2 in HBCs, BMP6 and BMP7 in 143B cultures, and BMP2 and BMP7 in SaOS-2 cultures. Better ALP and calcification results were obtained in SaOS-2 cultures when PRP was added more frequently at shorter intervals while poor results were obtained after single PRP addition. CONCLUSIONS: The results highlight induction of bone cell proliferation and differentiation by PRP. Since repeated administration of PRP is needed to achieve the best results, an almost continuous delivery system of PRP, or better a controlled release of growth and differentiation factors, using biomaterials might provide increased performance at bone regeneration sites.

Plasma exchange in acute and chronic hyperviscosity syndrome: a rheological approach and guidelines study.

Therapeutic plasma exchange is an extra-corporeal technique able to remove from blood macromolecules and/or replace deficient plasma factors. It is the treatment of choice in hyperviscosity syndrome, due to the presence of quantitatively or qualitatively abnormal plasma proteins such as paraproteins. In spite of a general consensus on the indications to therapeutic plasma exchange in hyperviscosity syndrome, data or guide lines about the criteria to plan the treatment are still lacking. We studied the rheological effect of plasma exchange in 20 patients with plasma hyperviscosity aiming to give data useful for a rational planning of the treatment. Moreover, we verified the clinical applicability of the estimation of plasma viscosity by means of Kawai's equation. Plasma exchange decreases plasma viscosity about 20-30% for session. Only one session is required to normalize plasma viscosity when it is < 2.2 mPas, whereas a maximum of 3 session are required when it is > 2.2 till to 6 mPas. A fourth session is useless, especially if the inter-session interval is < 15 days. By means of a polynomial equation, knowing basal-plasma viscosity and the disease of a patient, we can calculate the decrease of viscosity obtainable by each session of plasma exchange then the number of session required to normalize the viscosity. Kawai's equation is able to evaluate plasma viscosity in healthy volunteers, but it is not clinically reliable in paraproteinemias.