Accessible xenografts of human synovium in the subcutaneous tissues of theears of SCID mice

This work was undertaken to examine whether human synovium could be engraft ed into subcutaneous pouches in the ears of severe combined immunodeficient (SCID) mice. Synovium was transplanted into surgically constructed ear pou ches. The grafts were examined by histological and immunohistochemical meth ods after varying periods after engraftment, or after percutaneous injectio n of TNF-alpha. Normal, osteo-arthritic and rheumatoid synovium was engraft ed successfully in subcutaneous ear pouches. The general morphology and cel lular compositions of xenografts were retained including human endothelial cells. In rheumatoid xenografts, macrophages, fibroblasts and lymphocytes p ersisted for at least 4 weeks. Vascular expression of intercellular adhesio n molecule-1 (ICAM-1) was maintained but expression of vascular adhesion mo lecule-1 (VCAM-1), E-selectin and MHC class II diminished with time. Percut aneous injection of TNF-a induced up-regulation of VCAM-1. Human synovium c an be engrafted into subcutaneous ear pouches in SCID mice. The xenografts are accessible and respond to injection of a pro-inflammatory cytokine.