The understanding of cell migration after cell-based treatments is growing in osteoarthritis (OA), as it might influence the clinical outcome. Among biological alternatives, the adipose “niche” is emerging as a promising therapy being a rich cell source which can be available by enzymatic (SVF) and mechanical (MFAT) techniques. Herein, we investigated the migratory profile of expanded-adipose stromal cells (ASCs), SVF, and MFAT in a rabbit OA model at 7 and 30 days follow-up.
A mild grade of OA was surgically induced by bilateral anterior cruciate ligament transection in 18 rabbits. ASCs (n=6) and SVF (n=6) were obtained by collagenase NB4 treatment, whereas MFAT (n=6) by the mechanical technique in a one-step closed system (Lipogems device). In vitro biological studies on cells viability, surface marker characterization and morphology were carried out. For local biodistribution analysis, cells were labeled with PKH26, a fluorescent lipophilic membrane binding dye. After OA onset, 2x106 ASCs, SVF, and MFAT were intra-articularly injected into the knee joint and local biodistribution was evaluated at 7 and 30 days. Assessments on cell biodistribution and colocalization for PKH26 and CD-146 were done at short and long-term follow-ups. Histological assessments supported by specific scoring systems on osteochondral tissues and synovial membrane were carried out. The Monte Carlo method and the general linear model for multiple comparisons were used for statistics.
High cell viability and a distinct long-term migration were noticed for all groups. At day 7, ASCs and SVF displayed a high tropism for synovium while MFAT for cartilage; an opposite trend was noticed at day 30. Cartilage repair was noticed after MFAT, likewise to ASCs treatment.
The long-term presence of adipose cells might have a clinical significance ensuring a cellular reservoir to promote repair processes. The different migration could open interesting clinical insights on their use for OA treatment.