In Vitro Cartilage Regeneration with a Three-Dimensional Polyglycolic Acid (PGA) Implant in a Bovine Cartilage Punch Model

Int J Mol Sci. 2021 Oct 29;22(21):11769. doi: 10.3390/ijms222111769.


Resorbable polyglycolic acid (PGA) chondrocyte grafts are clinically established for human articular cartilage defects. Long-term implant performance was addressed in a standardized in vitro model. PGA implants (+/- bovine chondrocytes) were placed inside cartilage rings punched out of bovine femoral trochleas (outer Ø 6 mm; inner defect Ø 2 mm) and cultured for 84 days (12 weeks). Cartilage/PGA hybrids were subsequently analyzed by histology (hematoxylin/eosin; safranin O), immunohistochemistry (aggrecan, collagens 1 and 2), protein assays, quantitative real-time polymerase chain reactions, and implant push-out force measurements. Cartilage/PGA hybrids remained vital with intact matrix until 12 weeks, limited loss of proteoglycans from "host" cartilage or cartilage-PGA interface, and progressively diminishing release of proteoglycans into the supernatant. By contrast, the collagen 2 content in cartilage and cartilage-PGA interface remained approximately constant during culture (with only little collagen 1). Both implants (+/- cells) displayed implant colonization and progressively increased aggrecan and collagen 2 mRNA, but significantly decreased push-out forces over time. Cell-loaded PGA showed significantly accelerated cell colonization and significantly extended deposition of aggrecan. Augmented chondrogenic differentiation in PGA and cartilage/PGA-interface for up to 84 days suggests initial cartilage regeneration. Due to the PGA resorbability, however, the model exhibits limitations in assessing the "lateral implant bonding".

Keywords: articular cartilage regeneration; bovine cartilage punch model; polyglycolic acid (PGA); push-out test for implants.

MeSH terms

  • Absorbable Implants
  • Animals
  • Cartilage, Articular / cytology
  • Cartilage, Articular / injuries
  • Cartilage, Articular / physiology*
  • Cattle
  • Cells, Cultured
  • Chondrocytes / cytology*
  • Chondrocytes / metabolism
  • Chondrogenesis
  • Disease Models, Animal
  • Polyglycolic Acid / chemistry*
  • Regeneration*
  • Tissue Engineering
  • Tissue Scaffolds / chemistry*


  • Polyglycolic Acid