Human nasal polyp microenvironment maintained in viable and functional states as xenografts in SCID mice

Objectives: We undertook to maintain human nasal polyp tissue in a viable and functional state in SCID (severe combined immunodeficiency) mice. Methods: Small, nondisrupted pieces of human nasal polyp tissues were subcutaneously implanted into SCID mice depleted of natural killer cells. The resulting xenografts were examined histologically, and the sera were evaluated for the presence of human protein. Results: The original histologic architecture of the polyp was maintained in the xenografts. The tissues, including pseudostratified columnar epithelial-lined polyps and subepithelial stroma, remained viable, and goblet cells continued to produce mucin for up to 26 weeks after engraftment. Human inflammatory leukocytes, including CD3⁺ T cells, CD20 ⁺ B cells, CD138⁺ plasma cells, and CD68⁺ monocytes and/or macrophages, were present. Identification of human immunoglobulin and human interferon-γ in the sera of xenograft-bearing mice indicated that the B cells or plasma cells and T cells within the xenografts remained functional for 2 weeks after engraftment. Conclusions: The ability to engraft and maintain nasal polyps provides an in vivo human/mouse chimeric model with which to investigate the role of inflammatory leukocytes and stromal cells in the maintenance and progression of polyposis and to determine how exogenous cytokines may alter the interaction of inflammatory cells, stromal cells, and epithelial cells in the polyp.