Mesenchymal stem cell-derived Nano-Ghosts with innate targeting and immunomodulatory capabilities: A new approach for cartilage regeneration

Introduction: Osteoarthritis (OA) is the most common degenerative disease of the joints, leading to cartilage degradation and sclerosis of the underlying bone. One of the main hallmarks of OA is the extracellular matrix degradation which promotes inflammation and leads to further cartilage loss via an increase in matrix degrading enzymes. Mesenchymal stem cells (MSC) play an important role in inflammation reduction and their use for cartilage repair is increasing, due to their proposed aptitude to home, colonize and promote regeneration of injured tissues. We designed a new kind of nanoparticles, termed Nano-Ghosts (NG), derived from the cytoplasmic membrane of the MSCs. Retaining MSCs’ surface properties, NGs are expected to target damaged tissue. In this study we demonstrate that NGs can target human articular chondrocytes (AC) and cartilage explants and prevent inflammation.

Methods: NGs’ anti-inflammatory effects were studied in vitro, on both TNFα-stimulated and non-stimulated ACs and on human cartilage explants ex vivo. Targeting was evaluated by flow cytometry and confocal microscopy. Anti-inflammatory effect was assessed by qPCR and ELISA of both matrix degradation and inflammation markers such as NO production, IL6 and PGE2s production.

Results: Our studies have shown that NGs can efficiently target hAC in vitro and cartilage explants ex vivo, with increased (3-fold) targeting of in vitro inflamed cells or cartilage explants obtained from OA patients. Owing to their retention of MSCs’ membrane-associated immunomodulatory capabilities, the NGs were also found to reduce, by more than half, the mRNA and protein levels of multiple markers of inflammation and degeneration in inflamed OA cells, including such markers as NO₂, PGE2s, IL6, ADAMTS5, COX2, and MMP13. Finally, we have also demonstrated the NGs utility as a vehicle to selectively deliver a payload (LinkN peptide) with regenerative and anti-inflammatory capacities, increasing this payload concentration in target cells 10-fold compared to its free form.

Conclusion: With this proof-of-concept, we now plan to rapidly progress towards in vivo studies with OA mice models to prove the translational potential of our developments. Further studies are planned, as well, to investigate and enhance synergic effects between the NGs and different drug payloads. Finaly, NGs could open up new avenues towards the treatment of OA as a carrier for targeted delivery of therapeutics, such as anti-inflammatory agents and growth factors.