A microcarrier-based bioreactor offers many advantages in growing human mesenchymal stem cells. For example, hMSCs secrete high amounts of extracellular matrix, which enhances their adhesion on microcarriers. hMSCs also are sensitive to their microenvironment, and microcarrier-based bioreactors provide cells with a consistent and well-mixed culture environment, plus precise control of the temperature, pH, and dissolved oxygen. Consistency is key to preventing hMSC differentiation during expansion.