Figure 19.

(A) Agarose hydrogels loaded with human bone marrow mesenchymal stem cells (HMSC) are heated and cultured for 28 days to produce rigid osteochondral structures composed of bone and cartilage tissue by arranging glycosyl spions (superparamagnetic iron oxide nanoparticles) fields by using an external magnetic field. (Reproduced with permission from the Reference [133]). (B) Application of acoustic fluid-controlled perfusion bioreactor in the transplantation of new cartilage. The bioreactor is prepared by rectangular glass capillary, polydimethylsiloxane (PDMS) connector and ceramic piezoelectric sensor (PZT). Schematic diagram of the formation of multicellular condensation in a resonator. The transducer produces an ultrasonic standing wave field in the capillary cavity, and the glass surface above it acts as a reflector. When cells suspended in the culture medium are introduced into the chamber, acoustic radiation forces direct the cells to the pressure nodes, in which they can rapidly aggregate and eventually form multicellular clumps that are suspended in the chamber above the transducer. The closed loop includes a resonant cavity, a bubble trap, and a syringe pump for introducing cells into the cavity. Wires welded to the sensor electrodes are connected to a custom amplifier driven by a signal generator. Although ultrasonic activation causes heating, at the ambient temperature of the system (36 °C), the active region of the chamber is stable at 37.0, plus or minus 0.5 °C. (Reproduced with permission from the Reference [134]).