One of the most important clinical problems in caring for elderly patients is treatment of pressure ulcers. One component of normal wound healing is the generation of an inflammatory reaction, which is characterized by the sequential infiltration of neutrophils, macrophages and lymphocytes. Neutrophils migrate early in the wound healing process. In aged C57BL/6 mice, wound healing is relatively inefficient. We examined the effects of neutrophil numbers on wound healing in both young and aged mice. We found that the depletion of neutrophils by anti-Gr-1 antibody dramatically delayed wound healing in aged mice. The depletion of neutrophils in young mice had less effect on the kinetics of wound healing. Intravenous G-CSF injection increased the migration of neutrophils to the wound site. While the rate of wound repair did not change significantly in young mice following G-CSF injection, it increased significantly in old mice.

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SummaryThe wound repair process is a highly ordered sequence of events that encompasses haemostasis, inflammatory cell infiltration, tissue regrowth and remodelling. Wound healing follows tissue destruction so we hypothesized that antibodies might bind to wounded tissues, which would facilitate the engulfment of damaged tissues by macrophages. Here, we show that B cells, which produce antibodies to damaged tissues, are engaged in the process of wound healing. Splenectomy delayed wound healing, and transfer of spleen cells into splenectomized mice recovered the delay in wound healing. Furthermore, wound healing in splenectomized nude mice was also delayed. Transfer of enriched B220 + cells by magnetic beads accelerated wound healing in splenectomized mice. We detected immunoglobulin G1 (IgG1) binding to wounded tissues by using fluorescein isothiocyanate-labelled anti-IgG1 6-24 hr after wounding. Splenectomy reduced the amount of IgG1 binding to wounded tissues. Immunoblotting studies revealed several bands, which were reduced by splenectomy. Using immunoprecipitation with anti-IgG bound to protein G we found that the intensity of several bands was lower in the serum from splenectomized mice than in that from sham-operated mice. These bands were matched to myosin IIA, carbamoyl-phosphate synthase, argininosuccinate synthase, actin and a-actinin-4 by liquid chromatography tandem mass spectrometry analysis.

Angiogenic cell therapy represents a novel strategy for ischemic diseases, but some patients show poor responses. We investigated the therapeutic potential of an induced pluripotent stem (iPS) cell sheet created by a novel magnetite tissue engineering technology (Mag-TE) for reparative angiogenesis. Mouse iPS cell-derived Flk-1+ cells were incubated with magnetic nanoparticle-containing liposomes (MCLs). MCL-labeled Flk-1+ cells were mixed with diluted extracellular matrix (ECM) precursor and a magnet was placed on the reverse side. Magnetized Flk-1+ cells formed multi-layered cell sheets according to magnetic force. Implantation of the Flk-1+ cell sheet accelerated revascularization of ischemic hindlimbs relative to the contralateral limbs in nude mice as measured by laser Doppler blood flow and capillary density analyses. The Flk-1+ cell sheet also increased the expressions of VEGF and bFGF in ischemic tissue. iPS cell-derived Flk-1+ cell sheets created by this novel Mag-TE method represent a promising new modality for therapeutic angiogenesis.