This study aimed to find a simple, cost-effective, and time-efficient method for the preparation of platelet-rich plasma (PRP), so the acquired benefits will be readily available for multiple procedures in smaller outpatient clinics and to explore the safety and efficacy of the application of PRP in the treatment of degenerative lesions of articular cartilage of the knee. The study was designed as a prospective, cohort study with a control group. A total of 120 patients with Grade 1, 2, or 3 osteoarthritis according to the Kellgren and Lawrence grading scale were enrolled in the study. One group of patients was treated using three intra-articular applications of PRP, and the second group of patients was given three injections of hyaluronic acid. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index and the 11-point pain intensity Numeric Rating Scale. On average, a 4.5-fold increase in platelet concentration was obtained in the PRP group. No severe adverse events were observed. Statistically significantly better results in the Western Ontario and McMaster Universities Osteoarthritis Index and Numeric Rating Scale scores were recorded in a group of patients who received PRP injections after a 3- and 6-mo follow-up. Our preliminary findings support the application of autologous PRP as an effective and safe method in the treatment of the initial stages of knee osteoarthritis. Further studies are needed to confirm these results and to investigate the persistence of the beneficial effects observed.

Synovial membrane and synovial fluid represent a good source of mesenchymal stem cells. They have been regarded as a promising therapeutic tool for musculoskeletal regeneration. Synovium-derived mesenchymal stem cells have higher expression of CD44 and better chondrogenic potential in vitro than mesenchymal stem cells from other tissues. In this study we compared mesenchymal stem cells from synovium and synovial fluid on the base of morphological, immunophenotype and differentiation features. A heterogeneous population of cells with different morphology was obtained after isolation and 4-day cultivation. The mesenchymal stem cell immunophenotype was confirmed by positive expression of CD105, CD90, and CD44 by flow cytometry and cells were negative for CD45. CD105 ⁺ cells were selected by immunomagnetic separation after 2–4 weeks of cultivation. The percentage of CD105 ⁺ cells in the mesenchymal stem cell population from synovia was between 40–50 % before immunomagnetic separation and increased to 95 % following the immunomagnetic separation. Von Kossa, Alcian blue and Oil Red O staining was used to assess the differentiation potential of synovial mesenchymal stem cells. Long-term cultivation did not affect the morphology and immunophenotype of synovial mesenchymal stem cells. Our results confirmed that immunomagnetic separation based on CD 105 antigen is a suitable method to enrich the subpopulation of CD105 ⁺ synovial mesenchymal stem cells.

Two main types of macrophages (Mφ) include inflammatory (M1) and anti-inflammatory (M2) macrophages. These cells can be obtained in vitro by polarization of monocytic cell lines using various stimuli. Since there is currently no consensus on the best method for the acquisition of reliable M1 and M2 macrophages from the THP-1 cell line, we decided to compare three different polarization protocols at the transcriptomic level. Whole transcriptomes of Mφ polarized according to the chosen protocols were analyzed using RNA-seq. Differential expression of genes and functional enrichment for gene ontology terms were assessed. Compared with other protocols, M1 macrophages polarized using PMA (61.3 ng/mL) and IFN-γ along with LPS had the highest expression of M1-associated regulatory genes and genes for M1 cytokines and chemokines. According to the GO enrichment analysis, genes involved in defensive and inflammatory processes were differentially expressed in these Mφ. However, all three chosen protocols which use Vit D₃, IL-13/IL-4, and IL-4, respectively, failed to promote the polarization of macrophages with a reliable M2 phenotype. Therefore, optimization or development of a new M2 polarization protocol is needed to achieve macrophages with a reliable anti-inflammatory phenotype.

Articular cartilage has limited capacity for natural regeneration and repair. In the present study, we evaluated kartogenin (KGN), a bioactive small heterocyclic molecule, for its effect on in vitro proliferation and chondrogenic differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSCs) in monolayer culture and in co-culture models in vitro. OA osteochondral cylinders and hBMSCs were collected during total knee replacement. The effect of KGN on hBMSCs during 21 days of culture was monitored by real-time proliferation assay, immunofluorescence staining, histological assay, scanning electron microscopy (SEM) (imaging and multiplex enzyme-linked immunosorbent assay) ELISA assay. The rate of proliferation of hBMSCs was significantly increased by treatment with 10 µM KGN during nine days of culture. Histological and SEM analyses showed the ability of hBMSCs in the presence of KGN to colonize the surface of OA cartilage and to produce glycosaminoglycans and proteoglycans after 21 days of co-culture. KGN treated hBMSCs secreted higher concentrations of TIMPs and the secretion of pro-inflammatory molecules (MMP 13, TNF-α) were significantly suppressed in comparison with control without hBMSCs. Our preliminary results support the concept that 10 µM KGN enhances proliferation and chondrogenic differentiation of hBMSCs and suggest that KGN is a potential promoter for cell-based therapeutic application for cartilage regeneration.