title: Degradation and remodeling of small intestinal submucosa in canine Achilles tendon repair.
abstract: BACKGROUND
  Extracellular matrix derived from porcine small intestinal submucosa is used for the repair of musculotendinous tissues. Preclinical evaluation and clinical use have suggested that small intestinal submucosa extracellular matrix degrades rapidly after implantation and can be replaced by host tissue that is functionally and histologically similar to the normal tissue.
  
  
  METHODS
  The present study analyzed the temporal degradation of a ten-layer multilaminate device of small intestinal submucosa extracellular matrix used for the repair of canine Achilles tendon and examined the corresponding histological appearance of the remodeled tissue during the course of scaffold degradation. Devices were fabricated from small intestinal submucosa extracellular matrix labeled with 14C. The amount of 14C remaining in the remodeled graft was measured by liquid scintillation counting at three, seven, fourteen, twenty-eight, sixty, and ninety days after surgery. Blood, urine, feces, and other parenchymal tissues were also harvested to determine the fate of scaffold degradation products. Tissue specimens were prepared for routine histological analysis to examine the morphology of the remodeled graft at each time-point.
  
  
  RESULTS
  The small intestinal submucosa extracellular matrix graft degraded rapidly, with approximately 60% of the mass lost by one month after surgery, and the graft was completely resorbed by three months after surgery. The graft supported rapid cellular infiltration and host tissue ingrowth. By ninety days after surgery, the remodeled small intestinal submucosa extracellular matrix consisted of a dense collagenous tissue with organization, cellularity, and vascularity similar to that of normal tendon.
  
  
  CONCLUSIONS
  Small intestinal submucosa extracellular matrix is rapidly degraded after implantation for the repair of a musculotendinous tissue in this canine Achilles tendon repair model and is replaced by the deposition and organization of host tissue that is histologically similar to that of normal tissue.
authors.affiliation: McGowan Institute for Regenerative Medicine, University of Pittsburgh, 100 Technology Drive, Suite 200, Pittsburgh, PA 15219, USA.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Gilbert
authors.forename: Ann M
authors.initials: AM
authors.lastname: Stewart-Akers
authors.forename: Abby
authors.initials: A
authors.lastname: Simmons-Byrd
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Badylak
mesh_terms: D000125:Achilles Tendon / Q000166:cytology / Q000293:injuries / Q000502:physiology*; D000818:Animals; D002250:Carbon Radioisotopes; D004285:Dogs; D005109:Extracellular Matrix / Q000502:physiology / Q000637:transplantation*; D007413:Intestinal Mucosa / Q000166:cytology / Q000637:transplantation*; D007421:Intestine, Small / Q000166:cytology; D023421:Models, Animal; D013552:Swine; D014183:Transplantation, Heterologous
chemical_list: D002250:Carbon Radioisotopes