Evaluation of amotosalen and UVA pathogen-reduced apheresis platelets after 7-day storage.

BACKGROUND: Amotosalen/UVA pathogen-reduced platelet components (PRPCs) with storage up to 7 days are standard of care in France, Switzerland, and Austria. PRPCs provide effective hemostasis with reduced risk of transfusion-transmitted infections and transfusion-associated graft versus host disease, reduced wastage and improved availability compared with 5-day-stored PCs. This study evaluated the potency of 7-day PRPCs by in vitro characterization and in vivo pharmacokinetic analysis of autologous PCs. STUDY DESIGN AND METHODS: The in vitro characteristics of 7-day-stored apheresis PRPCs suspended in 100% plasma or 65% platelet additive solution (PAS-3)/35% plasma, thrombin generation, and in vivo radiolabeled post-transfusion recovery and survival of 7-day-stored PRPCs suspended in 100% plasma were compared with either 7-day-stored or fresh autologous conventional platelets. RESULTS: PRPCs after 7 days of storage maintained pH, platelet dose, in vitro physiologic characteristics, and thrombin generation when compared to conventional 7-day PCs. In vivo, the mean post-transfusion survival was 151.4 ± 20.1 h for 7-day PRPCs in 100% plasma (Test) versus 209.6 ± 13.9 h for the fresh autologous platelets (Control), (T-ΔC: 72.3 ± 8.8%: 95% confidence interval [CI]: 68.5, 76.1) and mean 24-h post-transfusion recovery 37.6 ± 8.4% for Test versus 56.8 ± 9.2% for Control (T-ΔC: 66.2 ± 11.2%; 95% CI: 61.3, 71.1). DISCUSSION: PRPCs collected in both 100% plasma as well as 65% PAS-3/35% plasma and stored for 7 days retained in vitro physiologic characteristics. PRPCs stored in 100% plasma for 7 days retained in vivo survival. Lower in vivo post-radiolabeled autologous platelet recovery is consistent with reported reduced count increments for allogenic transfusion.

R-spondin 1 is required for specification of hematopoietic stem cells through Wnt16 and Vegfa signaling pathways.

Hematopoietic stem cells (HSCs) are the therapeutic component of bone marrow transplants, but finding immune-compatible donors limits treatment availability and efficacy. Recapitulation of endogenous specification during development is a promising approach to directing HSC specification in vitro, but current protocols are not capable of generating authentic HSCs with high efficiency. Across phyla, HSCs arise from hemogenic endothelium in the ventral floor of the dorsal aorta concurrent with arteriovenous specification and intersegmental vessel (ISV) sprouting, processes regulated by Notch and Wnt. We hypothesized that coordination of HSC specification with vessel patterning might involve modulatory regulatory factors such as R-spondin 1 (Rspo1), an extracellular protein that enhances ß-catenin-dependent Wnt signaling and has previously been shown to regulate ISV patterning. We find that Rspo1 is required for HSC specification through control of parallel signaling pathways controlling HSC specification: Wnt16/DeltaC/DeltaD and Vegfa/Tgfß1. Our results define Rspo1 as a key upstream regulator of two crucial pathways necessary for HSC specification.

Ventromorphins: A New Class of Small Molecule Activators of the Canonical BMP Signaling Pathway.

Here, we describe three new small-molecule activators of BMP signaling found by high throughput screening of a library of ∼600 000 small molecules. Using a cell-based luciferase assay in the BMP4-responsive human cervical carcinoma clonal cell line, C33A-2D2, we identified three compounds with similar chemotypes that each ventralize zebrafish embryos and stimulate increased expression of the BMP target genes, bmp2b and szl. Because these compounds ventralize zebrafish embryos, we have termed them "ventromorphins." As expected for a BMP pathway activator, they induce the differentiation of C2C12 myoblasts to osteoblasts. Affymetrix RNA analysis confirmed the differentiation results and showed that ventromorphins treatment elicits a genetic response similar to BMP4 treatment. Unlike isoliquiritigenin (SJ000286237), a flavone that maximally activates the pathway after 24 h of treatment, all three ventromorphins induced SMAD1/5/8 phosphorylation within 30 min of treatment and achieved peak activity within 1 h, indicating that their responses are consistent with directly activating BMP signaling.