Nutrient Rescue of Early Maturing and Deteriorating Satellite Cell-Derived Engineered Muscle Tissue.

Engineered human muscle tissue is a promising tool for tissue models to better understand muscle physiology and diseases, since they can replicate many biomimetic structures and functions of skeletal muscle . We have developed a method to produce contractile muscle sheet tissues from human myoblasts, based on our cell sheet fabrication technique. This study reports that our tissue engineering technique allowed us to discover unique characteristics of human muscle satellite cells as a cell source for our muscle sheet tissue. The tissues engineered from satellite cells functionally matured within several days, which is earlier than those created from myoblasts. On the other hand, satellite cell-derived muscle sheet tissues were unable to maintain the contractile ability, whereas the myoblast-derived tissues showed muscle contractions for several weeks. The sarcomere structures and membrane-like structures of laminin and dystrophin were lost along with early functional deterioration. Based on a hypothesis that an insufficiency of nutrients caused a shortened lifetime, we supplemented the culture medium for the satellite cell-derived muscle sheet tissues with 10% serum, although a lower serum medium is commonly used to produce muscle tissues. Further combined with the transforming growth factor (TGF-β1) receptor inhibitor, SB431542, the contractile ability of the muscle tissues was increased remarkably and the tissue microstructures were maintained for a longer term, while retaining the early functionalization and the enriched culture conditions prevented early deterioration. These results strengthened our understanding of the biology of myoblasts and satellite cells in muscle tissue formation and provided new insights into the applications of muscle tissue engineering.