Extracellular matrix for myocardial repair.

OBJECTIVE: To evaluate the remodeling characteristics of an extracellular matrix (ECM) scaffold when used as a template for myocardial repair.
BACKGROUND: Xenogeneic ECM has been shown to be an effective scaffold for the repair and reconstitution of several tissues, including lower urinary tract structures, dura mater, the esophagus, musculotendinous tissues, and blood vessels. These ECM scaffolds are completely degraded in vivo and induce a host cellular response that supports. Constructive remodeling rather than scar tissue formation.
METHODS: Full-thickness circular defects measuring approximately 2.5 cm in diameter were created in the right ventricular anterior walls of 6 adult Yucatán pigs and 4 adult mongrel dogs. The defects were repaired with an ECM sheet 80 m thick that was derived from either the porcine small intestinal submucosa or the porcine urinary bladder matrix. The animals lived for periods of 6 to 24 weeks before sacrifice.
RESULTS: There was a complete replacement of the acellular scaffolds by a mixture of tissue types, including well-vascularized fibrous connective tissue, cartilage, adipose connective tissue, and myocardial tissue. The remodeled scaffold tissue showed spontaneous contractility and peak contractile force equivalent to 70% of the contractile force of the adjacent native myocardium.
CONCLUSIONS: We conclude that porcine ECM scaffolds alter the typical scar tissue healing response in myocardial tissue and instead support vascularization and the local development of multiple tissue types, including contractile myocardium.