Immunogenicity and tumorigenicity of hAFSCs. (A) FACS analysis for HLA-DR expression. HLA-DR expression in hAFSCs was lower than isotype (negative control with PE-conjugated antibody). (B) IHC staining of a retrieved urethral sphincter one week after hAFSCs injection. The cell-injected animal showed scant CD8 lymphocyte aggregation, while the cell (-) and human fibroblast-injected animals had significant CD8 lymphocyte accumulation (200×). Cell (-), pudendal neurectomy without cell injection; Cell (+), pudendal neurectomy with cell treatment; Ctrl(+), positive control with human fibroblast injection (200×). (C) H&E stain of kidney tissue retrieved eight weeks after renal subcapsular injection of hAFSCs. No teratoma formation was found at the injection site (100× and 200×).