Long‐term survival of hPSCs in muscles along with an aggravated immune response. At 60 days after intramuscular implantation, numerous hPSCs were still detected in the recipient muscles (n = 20) by HLA‐ABC immunostaining (A, B). A further increase in the severity of the local immune response, with formation of ectopic lymph node‐like structures was evident in proximity to the graft, as shown by immunostaining for CD3+ T cells (C, D) and Iba1+ macrophages (E, F). Characterization of macrophage polarization showed marked domination of classic iNOS+ (M1) macrophages (G, I) versus alternative dispersed Arg+ (M2) macrophages (H, J). Insets in (A, C, E, G, H) are magnified in (B, D, F, I, J), respectively. Scale bars = 500 µm (A, C, E, G, H) and 50 µm (B, D, F, I, J). Abbreviations: Arg, arginase; DAPI, 4′,6‐diamidino‐2‐phenylindole; HLA, human leukocyte antigen; iNOS, inducible nitric oxide synthase.