Purpose

Articular cartilage injuries can lead to significant joint morbidity. Although marrow stimulation procedures such as microfracture are a popular treatment option, results are often suboptimal, with the resultant neocartilage exhibiting a more fibrous than hyaline phenotype. Micronized matrix allograft cartilage has emerged as a promising new adjunct to augment microfracture procedures by promoting a greater degree of hyaline cartilage regeneration and improved long-term outcomes. However, little is known about the effects of micronized matrix allograft cartilage on a cellular level. The purpose of this study was to investigate the effects of micronized matrix allograft cartilage (BioCartilage) on multipotent stem cell differentiation.

Methods and Materials

Human mesenchymal stem cells (MSCs) were treated with BioCartilage (micronized matrix allograft cartilage; Arthrex Inc., Naples, FL) and/or human platelet-rich plasma (PRP). Chondrogenic differentiation was assessed using polymerase chain reaction (PCR) to measure expression of type II collagen (COL2), aggrecan (AGG), and SOX9 marker genes. Human adipose-derived stem cells (ADSCs) were also treated with BioCartilage; osteocalcin (OCN), alkaline phosphatase (ALP), and RUNX2 marker genes were used to measure osteogenic differentiation, and CD31 and VEGF were used to measure angiogenic differentiation.

Results

In the MSCs, BioCartilage resulted in significant increases in COL2 and SOX9 expression at various timepoints.(Figures 1, 2).

BioCartilage combined with PRP also demonstrated a synergistic effect on increasing AGG expression. In the ADSCs, BioCartilage did not affect OCN or RUNX2 expression, but did result in a decrease in ALP expression. BioCartilage also resulted in a decrease in CD31 expression, but an increase in VEGF expression.

Conclusion

This study supports the theory that micronized matrix allograft cartilage (BioCartilage) promotes hyaline cartilage differentiation of stem cells. The data also suggests that BioCartilage inhibits bone and blood vessel formation, which is important for maintaining cartilage regeneration in microfracture procedures.