CD47, also known as Integrin Associated Protein (IAP), is a transmembrane protein that belongs to the immunoglobulin superfamily. It is widely expressed on the surface of almost all normal cells and is highly expressed in tumor cells ^[1].

SIRPα, a signal regulatory protein mainly expressed on macrophages, inhibits their phagocytosis of target cells by transmitting inhibitory signals when binding to CD47 on other cells. However, some tumor cells can evade phagocytosis and cause tumor immune escape by highly expressing CD47 and binding to SIRPα on macrophages, sending a “don’t eat me” signal. Targeting CD47 antibodies can initiate anti-tumor T cell immune responses and promote cancer-specific lymphocyte activation through macrophage-mediated phagocytosis of tumors. As a result, the CD47-SIRPα signaling pathway has great therapeutic potential and is a highly competitive target in tumor immunotherapy after PD-1/PD-L1 ^[1-2].

CD47 is a transmembrane protein with its extracellular domain serving as the receptor/ligand binding region and its intracellular domain responsible for signal transduction ^[3]. B6-hCD47 mice are obtained by replacing the fragment encoding the extracellular domain of CD47 protein in the mouse Cd47 gene with the corresponding human CD47 gene sequence, resulting in a model expressing the extracellular domain of human CD47 protein and the intracellular domain of mouse CD47 protein. This ensures normal binding with human antibodies and other protein drugs while completely retaining the intracellular part of mouse CD47 protein, maintaining normal intracellular signal transduction. B6-hCD47 mice can successfully express human CD47 protein and can be used for research on CD47-targeted inhibitors or antibody drug development and screening, pharmacology and safety evaluation, tumor immunotherapy evaluation, and mechanisms of tumor immune escape systems.