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Although xenografts are one of the most attractive strategies for overcoming the shortage of organ donors, cellular rejection by macrophages is a substantial impediment to this procedure. It is well known that macrophages mediate robust immune responses in xenografts. Macrophages also express various inhibitory receptors that regulate their immunological function. Recent studies have shown that the overexpression of inhibitory ligands on porcine target cells results in the phosphorylation of tyrosine residues on intracellular immunoreceptor tyrosine-based inhibitory motifs on macrophages, leading to the suppression of xenogenic rejection by macrophages. It has also been reported that myeloid-derived suppressor cells, a heterogeneous population of immature myeloid cells, suppress not only NK and cytotoxic T lymphocyte cytotoxicity but also macrophage-mediated cytotoxicity. This review is focused on the recent findings regarding strategies for inhibiting xenogenic rejection by macrophages.

Sn/In–Sn bonding interfaces obtained by the transient liquid phase (TLP) reaction were investigated for applications in low-temperature assembly. Bonding was achieved at temperatures below 150 °C with a low bonding pressure. Although a few voids were formed at the interfaces after bonding, the In–Sn metallization enabled low-temperature bonding due to the low eutectic temperature. A bonding mechanism to achieve this novel In–Sn low-temperature assembly was also proposed.