Multi-omics identification of extracellular components of the fetal monkey and human neocortex.

During development, precursor cells are continuously and intimately interacting with their extracellular environment, which guides their ability to generate functional tissues and organs. Much is known about the development of the neocortex in mammals. This information has largely been derived from histological analyses, heterochronic cell transplants, and genetic manipulations in mice, and to a lesser extent from transcriptomic and histological analyses in humans. However, these approaches have not led to a characterization of the extracellular composition of the developing neocortex in any species. Here, using a combination of single-cell transcriptomic analyses from published datasets, and our proteomics and immunohistofluorescence analyses, we provide a more comprehensive and unbiased picture of the early developing fetal neocortex in humans and non-human primates. Our findings provide a starting point for further hypothesis-driven studies on structural and signaling components in the developing cortex that had previously not been identified.

Removal of exogenous (spiked) and endogenous prion infectivity from red cells with a new prototype of leukoreduction filter.

BACKGROUND: Two recent probable cases of transmission of a variant of human Creutzfeldt-Jakob disease (vCJD) through blood transfusion suggest that the disease can be transmitted through transfusion of blood components from presymptomatic blood donors. In the absence of a preclinical screening test, removal of the infectious agent by processing is the only means by which risk to recipients of blood from donors with inapparent vCJD infections can be eliminated. STUDY DESIGN AND METHODS: In the endogenous infectivity study, a pool of 500 mL of whole blood was collected into CP2D anticoagulant from 263K-strain scrapie-infected hamsters, processed into 300 mL of red cells (RBCs), and then passed through a prion removal filter. Pre- and postfiltration samples were tested for PrP(sc) by Western blot and for infectivity by inoculation of healthy hamsters. In the exogenous (spiking) infectivity study, 30 mL of 10 percent (wt/vol) scrapie-infected brain homogenates was added to 270 mL of human RBCs and then filtered. Levels of PrP(sc) and infectivity were determined by Western blot and bioassay. RESULTS: In the endogenous infectivity study, the prefiltered RBCs transmitted disease to 6 of 43 animals, whereas the postfiltered RBCs did not transmit disease to any of 35 animals, and a barely visible prefiltration PrP(sc) Western blot signal was reduced below the level of detection in the postfiltration sample. In the exogenous (spike) study, infectivity was reduced by 3.7 log LD50 per mL, from 9.2 to 5.5 log LD50 per mL. CONCLUSION: The new filter was effective in removing both infectivity and PrP(sc) from RBCs. The use of this type of filter should reduce the risk of vCJD transmission through blood transfusion.