Small Intestinal Submucosa Seeded with Intestinal Smooth Muscle Cells in a Rodent Jejunal Interposition Model

Background. Small intestinal submucosa (SIS) is a porcine-derived, acellular, collagen-based matrix that has been tested without seeded smooth muscle cells (SMCs) for intestinal tissue engineering. We examined the expression patterns of contractile proteins of SIS with SMCs implanted in an in vivo rodent model. Materials and Methods. Intestinal SMCs were isolated from Lewis rat pups. Four-ply tubular SMCs-seeded SIS or blank SIS scaffolds were implanted in an adult rat jejunal interposition model. Recipients were sacrificed at 2, 4, and 8 wk following the implantation. The retrieved specimens were examined using antibodies against contractile proteins of SMCs. Results. Cultured intestinal SMCs expressed alpha-smooth muscle actin (alpha-SMA), calponin, and less smooth muscle myosin heavy chain (SM-MHC) in vitro. Cell-seeded SIS scaffolds contracted significantly over 8 wk of implantation but were comparable to SIS scaffolds without cell seeding. Implanted cell-seeded SIS scaffolds at 2 wk expressed extensive alpha-SMA, some calponin, and minimal SM-MHC. At 4 wk, alpha-SMA-expressing cells decreased significantly, whereas calponin or SM-MHC expressing cells were rarely detected. A small number of alpha-SMA-expressing cells were present at 8 wk, whereas more calponin or SM-MHC expressing cells emerged in proximity with the anastomotic interface. Conclusions. Cell-seeded SIS contracted significantly after implantation, but the expressions of contractile proteins were present at the site of SIS interposition. No organized smooth muscle was formed at the site of implantation. A better scaffold design is needed to produce structured smooth muscle. (C) 2011 Elsevier Inc. All rights reserved.