Mesenchymal Stem Cell Therapy in Chondral Defects of Knee: Current Concept Review

Application Effect of Different Concentrations of Platelet-Rich Plasma Combined with Quadriceps Training on Cartilage Repair of Knee Osteoarthritis

We investigated the application effect of different concentrations of platelet-rich plasma (PRP) combined with quadriceps training on cartilage repair of knee osteoarthritis. Data of 37 patients with knee osteoarthritis (KOA) treated in our hospital (November 2019–February 2021) were retrospectively analyzed and the patients were divided into low concentration group (LCG) (n = 12), medium concentration group (MCG) (n = 12), and high concentration group (HCG) (n = 13) according to the order of admission. All patients received quadriceps training. Three groups above received knee injection of PRP, and the platelet concentrations were 1000–1400 × 10⁹/L, 1400–1800 × 10⁹/L, and 1800–2100 × 10⁹/L, respectively. Articular cartilage thickness of the medial and lateral femur, knee joint function scores, inflammatory factor levels, and matrix metalloproteinases (MMPs) levels were compared. After treatment, compared with the MCG and HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the LCG was obviously lower (P < 0.05). At 2 months after treatment (T₃), compared with the HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the MCG was obviously higher (P < 0.05), without remarkable difference in articular cartilage thickness of the medial and lateral femur of the healthy side among three groups (P > 0.05). After treatment, compared with the LCG, knee joint function scores of the MCG and HCG were obviously better (P < 0.001). Compared with the HCG, the knee function score at T₃ in the MCG was obviously better (P < 0.001). After treatment, compared with the LCG, inflammatory factor levels and levels of MMPs in the MCG and HCG were obviously lower (P < 0.05). Compared with the HCG, inflammatory factor levels and levels of MMPs at T₃ in the MCG were obviously lower (P < 0.05). PRP combined with quadriceps training can accelerate cartilage repair of patients with KOA and reduce inflammatory factor levels and levels of MMPs, but the treatment effect of PRP depends on platelet concentration, with the best range of 1400–1800 × 10⁹/L. Too high or too low platelet concentrations will affect recovery of knee function.

Adeno-Associated Virus-Mediated Overexpression of Interleukin-10 Affects the Immunomodulatory Properties of Equine Bone Marrow-Derived Mesenchymal Stem Cells

Joint injury can cause posttraumatic inflammation, which if severe enough can lead to posttraumatic osteoarthritis (PTOA), a progressive and debilitating condition. Posttraumatic inflammation is characterized by an influx of T lymphocytes and upregulation of inflammatory cytokines and degradative enzymes by activated chondrocytes and synoviocytes. Intra-articular bone marrow-derived mesenchymal stem cell (BM-MSC) injection for the treatment of osteoarthritis (OA) has been of interest due to the immunomodulatory properties of these cells. Interleukin (IL)-10, a potent immunomodulatory cytokine, has also been investigated as an OA therapeutic. Therefore, the objective of this study was to evaluate the combinatorial effects of BM-MSCs and IL-10 in OA using a gene therapy approach. We hypothesized that BM-MSCs overexpressing IL-10 would have superior immunomodulatory effects leading to increased suppression of T cell proliferation and decreased production of proinflammatory cytokines, providing protection of the extracellular matrix (ECM) in a stimulated, co-culture OA model. Treatment groups included the following: untransduced BM-MSC, adeno-associated virus (AAV)-IL10-transduced BM-MSC, and AAV-null transduced BM-MSC, which were unstimulated or stimulated with IL-1β/tumor necrosis factor-α (TNF-α). T cell proliferation was significantly decreased by the presence of BM-MSCs, especially when these BM-MSCs were AAV transduced. There was no significant difference in T cell suppression when cells were cultured with AAV-IL10-transduced or AAV-null transduced BM-MSCs. AAV transduction itself was associated with decreased synthesis of IL-1β, IL-6, and TNF-α. Expression of IL-1β and MMP13 was downregulated in AAV-transduced BM-MSCs and MMP13 expression was downregulated in cartilage explants co-cultured with AAV-transduced BM-MSCs. Despite mitigation of some proinflammatory cascades, rescue of ECM loss, as determined by glycosaminoglycan quantification and histological evaluation, did not occur in either AAV-IL10-transduced or AAV-null transduced co-cultures. Although IL-10 overexpression may enhance BM-MSC-mediated T cell suppression, we did not observe significant modulation of inflammation-driven cartilage degradation in cultures containing AAV-IL10-transduced BM-MSCs. AAV transduction itself does appear to affect paracrine signaling by BM-MSCs, which warrants further investigation.