Platelet-rich plasma (PRP) is believed to provide pain relief and help improve joint function in degenerative joint disease, a new study has shown that it does not act by promoting stem cell proliferation or enhance the cartilage formation capabilities of mesenchymal stem cells (MSCs).

In the article entitled "Effect of Platelet-rich Plasma on Chondrogenesis of Adipose- and Bone Marrow-Derived Stem Cells," coauthors Jr-Jium Liou, Benjamin Rothrauff, Peter Alexander, and Rocky Tuan, University of Pittsburgh School of Medicine (PA), used MSCs derived from the fat pad of the knee and the bone marrow.

They showed that high concentrations of PRP treatment for long periods of time impaired cartilage formation, making it less likely for chondrocyte differentiation from the MSC to occur. This had significant implications for the development of future strategies to repair cartilage damaged by injury or disease.

"This article presents a systematic study to elucidate the effects of PRP on the chondrogenic differentiation of adult human MSCs and its potential mechanism of action as a therapeutic adjunct for the treatment of joint diseases," said Antonios G. Mikos, Ph.D., Louis Calder Professor at Rice University, Houston, TX.

Post-traumatic and focal cartilage defects of the knee affect over 3 million Americans annually. Autologous cell-based cartilage repair, for example, autologous chondrocyte implantation, is limited by the need for ex vivo chondrocyte expansion and donor site morbidity.

IFP-ASC or BM-MSC chondrogenesis

Mesenchymal stem cells (MSCs), owing to their relative ease of isolation, higher replication activity, and chondrogenic potential, represent an alternative reparative cell type.

Platelet-rich plasma (PRP) is an autologous, growth factor-rich biologic preparation that has recently received increasing attention and use as a therapeutic adjunct for the treatment of degenerative joint diseases, and there is evidence suggesting that PRP acts by promoting stem cell proliferation and tissue healing.

In this study, the researchers examined the effect of PRP treatment on chondrogenic differentiation of adult human MSCs derived from infrapatellar fat pad-adipose stem cells (IFP-ASCs) and bone marrow (BM-MSCs).

Both cell types were placed in high-density pellet culture and hydrogel-encapsulated culture under chondrogenic conditions. Our results showed that PRP did not improve IFP-ASC or BM-MSC chondrogenesis.

In general, chondrogenesis was inhibited with increasing PRP concentrations and duration of exposure, by histological, biochemical, and gene expression analyses.

Taken together, these findings suggest that although PRP is reported to be beneficial regarding pain relief and joint function improvement, its mechanism of action is unlikely to involve enhancement of MSC-mediated hyaline cartilage formation directly.