• Mesothelin (MSLN) is limitedly expressed in normal tissues, notably in the normal mesothelial cells of the pleura, peritoneum, and pericardium. It is anchored to the cell membrane and does not have a transmembrane or intracellular domain. Many solid tumors overexpress MSLN, and high levels of expression are associated with poorer prognosis. Drugs targeting MSLN include monoclonal antibodies, antibody-drug conjugates (ADCs), bispecific antibodies, CAR-T, and CAR-NK.
• The genome of mouse Msln gene was replaced by human MSLN genome in B-NDG MHC I/II DKO/hMSLN mice. The murine B2m and H2-Ab1 gene were knocked out while a fused gene composed of murine B2m and Fcgrt gene was inserted after the signal peptide sequence of murine Fcgrt gene in B-NDG MHC I/II DKO/hMSLN mice.
• Human MSLN was detectable in homozygous B-NDG MHC I/II DKO/hMSLN mice. Mouse H-2Kb/H-2Db (MHC-I) and I-Ak (MHC-II) were not detectable in B-NDG MHC I/II DKO/hMSLN mice.
• This product is used for pharmacological and safety evaluation of drugs or cell therapies targeting MSLN.

Gene targeting strategy for B-NDG MHC I/II DKO/hMSLN mice. The murine B2m and H2-Ab1 gene were knocked out while a fused gene composed of murine B2m and Fcgrt gene was inserted after the signal peptide sequence of murine Fcgrt gene in B-NDG MHC I/II DKO/hMSLN mice. Exons 10-17 of the mouse Msln gene that encode the full-length protein were replaced by human MSLN exons 11-18 in B-NDG MHC I/II DKO/hMSLN mice. The promoter, 5’ UTR and 3’UTR region of the mouse gene are retained. The human MSLN expression is driven by endogenous mouse Msln promoter, while mouse Msln gene transcription and translation will be disrupted.

Strain specific H-2Kb/H-2Db (MHC-I) and I-Ak (MHC-II) expression analysis in B-NDG mice and B-NDG MHC I/II DKO/hMSLN mice by flow cytometry. Splenocytes were collected from B-NDG mice and B-NDG MHC I/II DKO/hMSLN mice. Protein expression was analyzed with anti-mouse H-2Kb/H-2Db antibody (Biolegend, 114613) and anti-mouse I-Ak antibody (Biolegend, 109908) by flow cytometry. Mouse H-2Kb/H-2Db (MHC-I) and I-Ak (MHC-II) was only detectable in B-NDG mice, but not in B-NDG MHC I/II DKO/hMSLN mice.

Strain specific MSLN expression analysis in B-NDG mice and homozygous B-NDG MHC I/II DKO/hMSLN mice by western blot. Lung, ovary and stomach were collected from B-NDG mice (+/+) and homozygous B-NDG MHC I/II DKO/hMSLN mice (H/H). Protein expression was analyzed with anti-mouse MSLN antibody (Abcam, ab187063) and anti-human MSLN antibody (Abcam, ab93620) by western blot. Mouse MSLN was only detectable in B-NDG mice. Human MSLN was exclusively detectable in homozygous B-NDG MHC I/II DKO/hMSLN mice, but not in B-NDG mice.