Optimal method for isolation of human peritoneal mesothelial cells from clinical samples of omentum

INTRODUCTION: Human peritoneal mesothelial cells (HPMC) are a valuable research tool for understanding the molecular biology of several pathologies, in both monolayer and three dimensional models. We compared different methods of HPMC isolation and assessed their outcome as well as fibroblast contamination, a common problem encountered during isolation. METHODS: 1-3cm(3) samples of omentum were collected from 40 consenting patients undergoing elective gastrointestinal surgery. A total of 11 samples were incubated in 0.05% trypsin solution for 20 minutes at 37 degrees C (group A) and 29 in 0.25% trypsin (15 samples for 10 minutes (group B) and 14 for 20 minutes (group C)). Following digestion cells were re-suspended and cultured in supplemented Ham's F-12 medium containing 10% foetal calf serum (FCS), penicillin-streptomycin, glutamine, insulin, transferrin and hydrocortisone. Positive outcomes were absence of fibroblast contamination and satisfactory HPMC growth to confluence in a characteristic cobblestone pattern. Cytokeratins 5, 8, 18, Vimentin, Ber-Ep4 and Factor VIII were used to characterise HPMC and fibroblasts by immunohistochemistry. RESULTS: None of the 11 samples in group A yielded HPMC. 14 of 29 samples digested with 0.25% trypsin yielded HPMC: 10 of 14 yielded HPMC in group C versus four of 15 samples in group B (p = 0.02). Fibroblast contamination occurred in eight samples in group B versus three in group C. CONCLUSION: Optimal results are achieved with a 20 minute digestion in 0.25% trypsin. Fibroblast contamination could not be avoided completely. Other factors may minimise fibroblast contamination such as minimal tissue manipulation and early collection during surgery.