Effects of docosahexaenoic acid or arachidonic acid supplementation on the behavior of cardiomyocytes derived from human pluripotent stem cells

Background:Human heart changes its energetic substrates from lactate and glucose to fatty acids during the neonatal period.Noticing the lack of fatty acids in media for the culture of cardiomyocytes derived from human pluripotent stem cells(hiPS-CM),researchers have supplemented mixtures of fatty acids to hiPS-CM and reported the enhancement in the maturation of hiPS-CM.In our previous studies,we separately supplemented two polyunsaturated fatty acids(PUFAs),docosahexaenoic acid(DHA)or arachidonic acid(AA),to rat fetal cardiomyocytes and found that the supplementations upregulated the expressions of mRNAs for cardiomyocyte differentiation,fatty acid metabolism,and cellular adhesion.The enhancement in cellular contractility was attributed to the improvement in intercellular connection rather than a direct enhancement of the contractile force.Methods:This study reports the successive results of the effects of DHA or AA supplementation on hiPS-CM.In addition to the contractile force and mRNA measurements used in the previous study,we further investigated the effect of different cellular aggregations on the contractile force output by means of finite element analysis,measured glucose and fatty acids metabolites,and assessed cTNT and MLC2v expressions through immunofluorecsence evaluation.Results:It showed that the sole supplementation of albumin-conjugated DHA or AA can be taken up by hiPS-CM without other uptake-enhancing factors,and the supplementations may activate the CD36_ERRγmetabolic pathway.DHA or AA supplementation increased the cellular contractile ratio on collagen gels and AA supplementation stimulated hiPS-CM aggregation to form cellular clusters.The enhancement effect on the hiPS-CM contractile force was modest since the increase in contractile force was not significant.AA supplementation was more effective than DHA supplementation because it significantly upregulated mRNA expressions of P300 and CD36.However,finite element analysis showed that the formation of clusters on a collagen gel attenuated the contractile force exerted by the gel on its surroundings.Conclusion:DHA and AA,as having been supplemented in infant formulas,have no direct and significant enhancement effect on the performance of the hiPS-CM when they were supplemented individually,although they were able to enter the cellular metabolic system.The AA supplementation showed some auxiliary effect on the maturation of hiPS-CM,which is worthy of further investigation under the consideration of membrane composition alteration and remodeling of membrane molecules.

Effects of docosahexaenoic acid or arachidonic acid supplementation on gene expression and contractile force of rat cardiomyocytes in primary culture

While fatty acids play essential roles in the physiology of the myocardium,conventional culture media contain little lipid.We previously revealed that rat neonatal myocardium mainly contains docosahexaenoic(DHA),linoleic(LA),and arachidonic(AA)acids as polyunsaturated fatty acids(PUFAs),and these contents in cultured cardiomyocytes derived from fetal rats were markedly lower than those in the neonatal myocardium.In this study,we first assessed the effects of supplementation of DHA,LA,or AA on the fatty acid contents and the percentage change of contractile area in primarily cultured rat cardiomyocytes.Based on this assessment,we then evaluated the effects of DHA or AA supplementation on mRNA expression and further directly measured the contractile force of cardiomyocytes with the supplementations.This study revealed that percentage change of contractile area was maximized under 20μM DHA or 50μM AA supplementation while LA supplementation did not affect this contraction index,and that a widespread upregulation tendency of the mRNA expression related to differentiation,maturity,fatty acid metabolism,and cell adhesion was seen in the cultured cardiomyocytes with supplementation of DHA or AA.In particular,upregulation of the gene expression of cellular adhesion molecules connexin43 and N-cadherin were remarkable,whereas the effects on differentiation and maturation were less pronounced.Correspondingly,the increase of the percentage change of the contractile area of cardiomyocyte clusters in culture dishes with the supplementations was significant,whereas the enhancement of the contractile force was modest.These results suggest that supplementation of DHA or AA to the fetal cardiomyocyte culture may play effective roles in preventing the de-differentiation of the cardiomyocytes in culture and that the enhancement of the contractile performance may be mainly attributed to the improvement of intercellular connection.

Lipoprotein lipase and obesity

Obesity is one of the fast-growing major diseases in developed and developing countries. As has been persuasively argued, long-term imbalance between intake and expenditure of fat is a central factor in the etiology of obesity. Obesity aggravates insulin resistance and promotes cardiovascular diseases and atherosclerosis. We hypothesized that elevating lipoprOtein lipase (LPL) activity in skeletal muscle would cause an improvement of obesity. To test this hypothesis, we studied the effects of the LPL activator NO-1886 inobese animals. NO-1886 elevated LPL activity in skeletal muscle, and improved obesity as well as insulin resistance in obese rats. Furthermore, NO-1886 mitigated body weight gain induced by pioglitazone without suppressive effect on the adiponectin-increasing action of pioglitazone. LPL activators hold a lot of promise of curing several diseases shown above in clinical scene.

Effects of Fasting on Plasma Lipoprotein(a) in Cynomolgus Monkeys: Preliminary Experiments Results

Plasma lipoprotein(a) (Lp(a)) is known to be a strong independent risk factor for ischemic heart disease. However, it is not easily modulated by drugs that are presently available. Lp(a) is not present in many experimental animals except for Old World monkeys. In this study, we examined whether cynomolgus monkeys are useful model for research of human plasma Lp(a), and observed that plasma Lp(a) in cynomolgus monkeys varied as much as humans. As a result of 4 day-fasting in cynomolgus monkeys, the plasma Lp(a) level decreased in a monkey with originally high Lp(a) level. The Lp(a) level continued to decrease even 3 days after banana feeding, but returned to the original level 3 days after monkey chow feeding. On the other hand, in a monkey with low Lp(a) level, fasting had no effect on the Lp(a) level. However, in the third monkey having originally high Lp(a) level, the Lp(a) was not affected by decreasing the amount of monkey chow feeding by 50%. In summary, we found that cynomolgus monkeys may be an useful model for studying the effects of food on plasma Lp(a) in place of humans, and that high Lp(a) level may be controllable by strict diet regulation.