RESEARCH ARTICLE Primary Myofibroblasts Maintain Short-Term Viability following Submucosal Injection in Syngeneic, Immune-Competent Mice

Themyofibroblast is an important stromal cell of the gastrointestinal tract. Current in vitro and in vivomodels either do not accurately recreate stromal-epithelial interactions or are not spe-cific to myofibroblasts. We sought to create an animal model that would allow the study of myofibroblast-epithelial interactions. We isolated and cultured colonic myofibroblasts from FVBmice. Cells were α-SMA and vimentin positive but desmin negative on immunoblot anal-ysis. We injected the myofibroblasts into the colonic submucosa of syngeneic adult mice (n = 8) via a miniendoscopic system. We then isolated green fluorescent protein (GFP) positive colonic myofibroblasts from C57BL/6-Tg(CAG-EGFP)1Osb/J mice and injected them into the colonic lamina propria of C57BL/6J mice at 1x105 (n = 14), 1x106 (n = 9), or 5x106 cells/mL (n = 4). A subset of mice were injected with serum-free media and ink without cells (n = 3). Mice underwent repeat endoscopy and euthanasia one or 7 days after injection. Colons were isolated and either fixed in 10 % formalin or the inked sites were individually excised and lysed for DNA.We assessed the injection sites via histology and immunohistochemical stains for α-SMA and GFP.We used qPCR to quantify GFP DNA transcripts at the lamina propria injec