Folic acid is necessary for proliferation and differentiation of C2C12 myoblasts.

Folic acid, a water soluble B vitamin, plays an important role in cellular metabolic activities, such as functioning as a cofactor in one-carbon metabolism for DNA and RNA synthesis as well as nucleotide and amino acid biosynthesis in the body. A lack of dietary folic acid can lead to folic acid deficiency and result in several health problems, including macrocytic anemia, elevated plasma homocysteine, cardiovascular disease, birth defects, carcinogenesis, muscle weakness, and walking difficulty. However, the effect of folic acid deficiency on skeletal muscle development and its molecular mechanisms are unknown. We, therefore, investigated the effect of folic acid deficiency on myogenesis in skeletal muscle cells and found that folic acid deficiency induced proliferation inhibition and cell cycle breaking as well as cellular senescence in C2C12 myoblasts, implying that folic acid deficiency influences skeletal muscle development. Folic acid deficiency also inhibited differentiation of C2C12 myoblasts and induced deregulation of the cell cycle exit and many cell cycle regulatory genes. It inhibited expression of muscle-specific marker MyHC as well as myogenic regulatory factor (myogenin). Moreover, immunocytochemistry and Western blot analyses revealed that DNA damage was more increased in folic acid-deficient medium-treated differentiating C2C12 cells. Furthermore, we found that folic acid resupplementation reverses the effect on the cell cycle and senescence in folic acid-deficient C2C12 myoblasts but does not reverse the differentiation of C2C12 cells. Altogether, the study results suggest that folic acid is necessary for normal development of skeletal muscle cells.

Platelet-derived growth factor improves cardiac function in a rodent myocardial infarction model.

OBJECTIVES: The translation of cardioprotective therapies for myocardial infarction requires a preclinical demonstration of improved cardiovascular function following acute coronary occlusion. We previously showed that pretreatment of rodent hearts with platelet-derived growth factor (PDGF) promotes angiogenesis and decreases the extent of myocardial injury measured by histology. The present study aimed to determine the correlation of these histological findings with noninvasive measures of improvement in cardiac function. METHODS: Rats were treated with intramyocardial injections of PDGF (100 ng) or phosphate buffer solution (PBS) (n = 6 per group) 24 h prior to acute, permanent ligation of the left anterior descending artery and the extent of myocardial injury was assessed by Masson's trichrome staining 14 days later. To assess the physiological effects of PDGF pretreatment after coronary occlusion, cardiac function was assessed noninvasively by electrocardiography, exercise testing and echocardiography and correlated with direct histological measures. RESULTS: Physiological studies demonstrated that PDGF resulted in lower ST-segment elevation at the time of coronary occlusion (0.12 +/- 0.02 mV above baseline) than in PBS control rats (0.35 +/- 0.05 mV; P < 0.05). Exercise testing 14 days after coronary occlusion revealed that PDGF pretreatment resulted in faster maximal exercise speeds (28.54 +/- 3.98 m/min) than in control rats (24.98 +/- 3.13 m/min; P < 0.05). Echocardiography also revealed that the left ventricular factional shortening in the PDGF-pretreated rats was significantly greater (18.47 +/- 12.21%) than in control animals (4.91 +/- 7.21%; P<0.05). CONCLUSIONS: These studies demonstrate that PDGF pretreatment improves cardiac function following acute coronary occlusion. Strategies based on the cardioprotective actions of PDGF may provide a significant advance in the treatment of myocardial infarction.