A novel extracellular vesicles production system harnessing matrix homeostasis and macrophage reprogramming mitigates osteoarthritis.

Osteoarthritis (OA) is a degenerative disease that significantly impairs quality of life. There is a pressing need for innovative OA therapies. While small extracellular vesicles (sEVs) show promising therapeutic effects against OA, their limited yield restricts clinical translation. Here, we devised a novel production system for sEVs that enhances both their yield and therapeutic properties. By stimulating mesenchymal stem cells (MSCs) using electromagnetic field (EMF) combined with ultrasmall superparamagnetic iron oxide (USPIO) particles, we procured an augmented yield of EMF-USPIO-sEVs. These vesicles not only activate anabolic pathways but also inhibit catabolic activities, and crucially, they promote M2 macrophage polarization, aiding cartilage regeneration. In an OA mouse model triggered by anterior cruciate ligament transection surgery, EMF-USPIO-sEVs reduced OA severity, and augmented matrix synthesis. Moreover, they decelerated OA progression through the microRNA-99b/MFG-E8/NF-κB signaling axis. Consequently, EMF-USPIO-sEVs present a potential therapeutic option for OA, acting by modulating matrix homeostasis and macrophage polarization.

A New Classification System for Forearm Deformities Caused by Hereditary Multiple Osteochondromas.

PURPOSE: The objective of this study was to evaluate the Masada and Jo classifications for clinical use in patients with forearm deformity caused by hereditary multiple osteochondroma and propose a new classification system that is all-inclusive and can guide clinical management. METHODS: A retrospective review of 275 forearms was performed. A split-sample approach was used, where 138 forearms were analyzed to create a new classification, which was then validated on the remaining 137 forearms. Radiographs were reviewed to determine the number and location of osteochondromas and the presence of radial head dislocation (RHD) and to measure radiographic parameters. Multivariable logistic regression analysis was performed to identify radiological parameters associated with RHD. RESULTS: According to the Masada and Jo classifications, 95 of 275 forearms (34.5%) were unclassifiable. Analyses of the split group (n = 138) revealed 42 forearms with RHD. All these had distal ulna lesions, qualifying as the greatest associated factor for RHD. Further subgroup multivariable logistic regression analysis of forearms with distal ulna lesions identified radiological parameter proportional ulna length as a statistically significant association of RHD, qualifying as "at-risk" criteria. The area under the receiver operating characteristic curve for proportional ulna length was 0.89, with a receiver operating characteristic-derived ideal value of ≤ 0.95 (sensitivity 0.86 and specificity 0.86). CONCLUSIONS: We proposed a new classification system stratified into three groups-high, moderate, and low-risk of RHD-based on the identified factors associated with RHD. Type 1 comprises forearms with distal ulna osteochondromas-subdivided into type 1A (high-risk), where forearms meet the at-risk criteria for RHD and type 1B (moderate-risk), where forearms do not meet the at-risk criteria. Type 2 (low-risk) comprises forearms without distal ulna osteochondromas. CLINICAL RELEVANCE: Our classification system addresses the limitations of existing classifications by risk stratifying forearms into three groups-high, moderate, and low-risk of RHD.

Scalable mesenchymal stem cell enrichment from bone marrow aspirate using deterministic lateral displacement (DLD) microfluidic sorting.

The growing interest in regenerative medicine has opened new avenues for novel cell therapies using stem cells. Bone marrow aspirate (BMA) is an important source of stromal mesenchymal stem cells (MSCs). Conventional MSC harvesting from BMA relies on archaic centrifugation methods, often leading to poor yield due to osmotic stress, high centrifugation force, convoluted workflow, and long experimental time (∼2-3 hours). To address these issues, we have developed a scalable microfluidic technology based on deterministic lateral displacement (DLD) for MSC isolation. This passive, label-free cell sorting method capitalizes on the morphological differences between MSCs and blood cells (platelets and RBCs) for effective separation using an inverted L-shaped pillar array. To improve throughput, we developed a novel multi-chip DLD system that can process 2.5 mL of raw BMA in 20 ± 5 minutes, achieving a 2-fold increase in MSC recovery compared to centrifugation methods. Taken together, we envision that the developed DLD platform will enable fast and efficient isolation of MSCs from BMA for effective downstream cell therapy in clinical settings.

A serum free approach towards the conservation of chondrogenic phenotype during in vitro cell expansion.

OBJECTIVE: Functionally viable chondrocytes in sufficient quantity is crucial for the success of matrix associated autologous chondrocyte implantation. This is difficult with conventional methods as chondrocytes dedifferentiate during 2D expansion with the loss of their chondrogenic phenotype. Moreover, established protocols are dependent on the use of serum which is not without its drawbacks. This study sought to address the issue by evaluating the feasibility of serum free, growth factors supplemented chondrocyte media with extracellular matrix (ECM) coatings. DESIGN: Passage 2 human chondrocytes were cultured in serum supplemented media or serum free media with collagen I or fibronectin coatings. Cell attachment and proliferation were assessed in these conditions. The cells were redifferentiated via pellet cultures for 7 and 14 days before being subjected to histological and gene expression analysis. RESULTS: The serum-free, growth factor cocktail supplemented with ECM coating improved long-term chondrocyte proliferation with enhanced basal Sox 9 expression. Upon induction, the redifferentiated chondrocytes expressed aggrecan and collagen II especially so for the cells plated on collagen coated surfaces. The chondrocytic phenotype was better conserved under the serum free conditions but the loss of the hyaline cartilage characteristics was not completely halted given the expression of collagen I. These essential cartilage markers were, however, reduced or absented for cells expanded with serum. Moreover, serum cultures displayed a higher tendency of undergoing hypertrophy given the stronger collagen X gene expression. CONCLUSION: The advocated technique promoted cell expansion with respect to conventional serum supplemented cultures while reducing the loss of the chondrogenic phenotype. This demonstrates the feasibility and potential of the novel concomitant use of serum free media and ECM coatings in the expansion of chondrocytes for cartilage regenerative applications.