Small intestinal submucosa versus salt-extracted polyglycolic acid-poly-L-lactic acid: a comparison of neocartilage formed in two scaffold materials.

This study sought to compare differences in neocartilage produced over time from two types of resorbable scaffold materials. One material was entirely synthetic and contained a polyglycolic acid-poly-L-lactic acid matrix (PGA-PLLA). The second scaffold material was bioactive and consisted of a four-layered construct of porcine small intestinal submucosa (SIS). Disk-shaped scaffolds were seeded with canine chondrocytes and implanted into athymic mice for periods of 5, 8, 12, and 24 weeks. Constructs were examined microscopically, assayed for hydroxyproline (HP) and glycosaminoglycan (GAG) content, and collagen typed (I or II) at each time period. Creep indentation tests determined aggregate and shear modulus, permeability, and thickness. Results indicated that SIS maintained its thickness through the first 12 weeks, and then doubled by week 24. The 24-week tissue appeared chondroid-like and possessed high GAG content. Tissues derived from PGA-PLLA scaffolds were lower in HP content than SIS-derived tissues, but type II collagen was demonstrated only in PGA-PLLA-derived tissues at 24 weeks. Mechanical properties were not significantly different for any tissue over time (p > 0.05), but aggregate and shear modulus mean values were consistently higher for PGA-PLLA-derived tissues at nearly every time interval. This, coupled with the presence of collagen types I and II, suggested a more congruent solid phase may be forming within the extracellular matrix of tissues derived from PGA-PLLA scaffolds. Future study is necessary to compare these materials under simulated loading conditions.