title: Biologic scaffold remodeling in a dog model of complex musculoskeletal injury.
abstract: BACKGROUND
  Current treatment principles for muscle injuries with volumetric loss have been largely derived from empirical observations. Differences in severity or anatomic location have determinant effects on the tissue remodeling outcome. Biologic scaffolds composed of extracellular matrix (ECM) have been successfully used to restore vascularized, innervated, and contractile skeletal muscle in animal models but limited anatomic locations have been evaluated. The aim of this study was to determine the ability of a xenogeneic ECM scaffold to restore functional skeletal muscle in a canine model of a complex quadriceps injury involving bone, tendon, and muscle.
  
  
  METHODS
  Sixteen dogs were subjected to unilateral resection of the distal third of the vastus lateralis and medial half of the distal third of the vastus medialis muscles including the proximal half of their associated quadriceps tendon. This defect was replaced with a biologic scaffold composed of small intestinal submucosa extracellular matrix (SIS-ECM) and the remodeling response was evaluated at 1, 2, 3, and 6 mo (N = 4 per group).
  
  
  RESULTS
  The initial remodeling process followed a similar pattern to other studies of ECM-mediated muscle repair with rapid vascularization and migration of myoblasts into the defect site. However, over time the remodeling response resulted in the formation of dense collagenous tissue with islands of muscle in the segments of the scaffold not in contact with bone, and foci of bone and cartilage in the segments that were adjacent to the underlying bone.
  
  
  CONCLUSIONS
  SIS-ECM was not successful at restoring functional muscle tissue in this model. However, the results also suggest that SIS-ECM may have potential to promote integration of soft and boney tissues when implanted in close apposition to bone.
authors.affiliation: McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA. badylaks@upmc.edu
authors.forename: Neill J
authors.initials: NJ
authors.lastname: Turner
authors.forename: John S
authors.initials: JS
authors.lastname: Badylak
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Weber
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Badylak
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002356:Cartilage / Q000502:physiology; D004195:Disease Models, Animal; D004285:Dogs; D004576:Electromyography; D005109:Extracellular Matrix / Q000502:physiology / Q000637:transplantation*; D005260:Female; D005269:Femur / Q000502:physiology; D007413:Intestinal Mucosa / Q000502:physiology / Q000637:transplantation*; D009119:Muscle Contraction / Q000502:physiology; D009140:Musculoskeletal Diseases / Q000601:surgery*; D052097:Quadriceps Muscle / Q000293:injuries* / Q000502:physiology / Q000601:surgery; D012038:Regeneration / Q000502:physiology; D013552:Swine; D013708:Tendon Injuries / Q000503:physiopathology / Q000601:surgery*; D054457:Tissue Scaffolds; D014183:Transplantation, Heterologous