X-irradiated umbilical cord blood cells retain their regenerative effect in experimental stroke.

Although regenerative therapy with stem cells is believed to be affected by their proliferation and differentiation potential, there is insufficient evidence regarding the molecular and cellular mechanisms underlying this regenerative effect. We recently found that gap junction-mediated cell-cell transfer of small metabolites occurred very rapidly after stem cell treatment in a mouse model of experimental stroke. This study aimed to investigate whether the tissue repair ability of umbilical cord blood cells is affected by X-irradiation at 15 Gy or more, which suppresses their proliferative ability. In this study, X-irradiated mononuclear (XR) cells were prepared from umbilical cord blood. Even though hematopoietic stem/progenitor cell activity was diminished in the XR cells, the regenerative activity was surprisingly conserved and promoted recovery from experimental stroke in mice. Thus, our study provides evidence regarding the possible therapeutic mechanism by which damaged cerebrovascular endothelial cells or perivascular astrocytes may be rescued by low-molecular-weight metabolites supplied by injected XR cells in 10 min as energy sources, resulting in improved blood flow and neurogenesis in the infarction area. Thus, XR cells may exert their tissue repair capabilities by triggering neo-neuro-angiogenesis, rather than via cell-autonomous effects.

Evaluation of HNA-expressing cell line-based antigen capture systems and a solid-phase system for detecting HNA-1a antibodies.

Granulocyte immunofluorescence and granulocyte agglutination tests are standard methods for detecting human neutrophil antigen (HNA) antibodies (Abs); however, these require a typed panel of neutrophils, which can be time-consuming to develop, and it remains difficult to determine antibody specificity in some cases. We established and evaluated four detection systems for HNA-1a Abs based on an HNA-1a-expressing cell line (KY cells) and antigen capture. We additionally evaluated a commercial solid-phase system. Eleven HNA-1a antibody-positive samples, including the World Health Organization Reference Reagent, and 40 serum samples derived from male blood donors were used as positive and negative control samples, respectively. Although specificity was >0.90 in all systems evaluated, the sensitivity varied among the systems. The KY cell-based monoclonal antibody specific immobilisation of granulocyte antigens (KY-MAIGA) system using certain, but not all, monoclonal Abs, and the solid-phase system revealed higher sensitivity than other systems. In conclusion, the KY-MAIGA and commercial solid-phase systems were superior in terms of specific and sensitive detection of HNA-1a Abs.