Hypoxia transactivates cholecystokinin gene expression in 3D-engineered muscle

Investigation of Brain Function-Related Myokine Secretion by Using Contractile 3D-Engineered Muscle

“…Recently, from the viewpoint of animal ethics issues [ 26 , 38 ], the demand for the use of novel “animal-free” 3D-culture models based on tissue engineering has increased in the fields of not only regenerative medicine [ 39 ] but also the health sciences [ 40 ]. Importantly, previous studies have only examined intracellular myokine expression [ 31 , 41 ], and we first established a platform to verify the secretion of myokines in 3D-EM, which is more mature than 2D muscle cell cultures (higher myosin heavy chain protein expression, data not shown). Indeed, numerous myokines are produced in response to exercise and function as “real polypills” by circulating in the body to target tissues and organs [ 42 ]; however, we have focused on brain health-related myokines given our previous study showing improved cognitive function in response to acute exercise [ 8 ].…”

“…The device for culturing skeletal muscle was partially modified from that used in previous studies. Two fixing points of the previous device were not deformed [ 30 , 31 ], whereas the device in the present study had pins on one side made of PDMS [ 45 ], which can be deformed and inclined, thereby allowing a wider contraction range for the evaluation of myokine secretion. We used a molded titanium scaffold (Zellez ™; Hi-Lex Corporation, Hyogo, Japan) as the artificial tendon, which was shown in a previous study [ 28 ].…”

“…The 3D-EM was constructed using C2C12 cells based on previous studies [ 28 , 30 , 31 ]. C2C12 cells were embedded in a cold type-1 collagen gel solution (Cellmatrix; Nitta Gelatin, Osaka, Japan) at a density of 1.5 × 10 7 cells/mL.…”

“…Thus, a 3D-EM may more closely represent in vivo muscles. Importantly, some myokines show higher intramuscular expression in 3D-EM than in 2D muscle cell cultures [ 31 ], which may uncover findings that would be unclear in 2D muscle cell cultures. Moreover, the EPS-evoked muscle contractile force in 3D-EM is 10 times higher than that in 2D muscle cell cultures [ 30 ].…”

Characteristics of the Protocols Used in Electrical Pulse Stimulation of Cultured Cells for Mimicking In Vivo Exercise: A Systematic Review, Meta-Analysis, and Meta-Regression

“…Two main groups of cell types were used in the included studies: a. cell lines and b. biopsies from humans and mice ( Table S2 ). More specifically, 30 of the eligible studies used cell lines: 24 studies employed the C2C12 cell line [ 16 , 17 , 26 , 28 , 30 , 31 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ], a mouse myoblast cell line; while one study used the L6 cell line [ 55 ], a rat myoblast cell line; one used primary human cells [ 13 ]; and one the H-2kb muscle cells (a mouse myoblast cell line) [ 56 ]. Of the remaining eligible studies, 12 used human skeletal muscle biopsies [ 18 , 19 , 20 , 21 , 23 , 24 , 25 , 29 , 50 , 57 , 58 , 59 , 60 ] from different sites, such as vastus lateralis, satellite cells, and rectus abdominis, obtained from healthy ( n = 64), lean ( n = 32), obese ( n = 20), and diabetic donors ( n = 4).…”