Figure 2.

Stem cell delivery for repairing articular cartilage defects or treating OA. (a) Cell-scaffold construct. Stem cells are planted on a tissue engineering scaffold, cultured in vitro until the cells adhere to the scaffold, and then, the cell-scaffold construct is implanted into the cartilage defect. (b) Magnetic targeting. Place a magnet on the back of the cartilage defect (popliteal fossa), use nanoiron particles to label stem cells, and then implant the stem cells into the cartilage defect. Under the attraction of the magnet, the stem cells are tightly fixed to the bottom of the cartilage defect. (c) Intra-articular injection. The stem cells are resuspended in hyaluronic acid (HA), phosphate-buffered saline (PBS), physiological saline or platelet-rich fibrin releasate (PRFr), and other carriers and then injected into the joint cavity. (d) Chondrocyte pellets. The stem cells are cultured and differentiated in vitro to form cartilage pellets, and then, the cartilage pellets are implanted into the cartilage defect. (e) Cell-hydrogel construct. The stem cells are mixed into the injectable hydrogel material, and then, the cell-hydrogel construct is injected into the cartilage defect.