A post-surgical adjunctive hypoxic therapy for myocardial infarction: Initiate endogenous cardiomyocyte proliferation in adults

Hypoxia-inducible factor-1: Regulatory mechanisms and drug therapy in myocardial infarction

Myocardial infarction (MI), an acute cardiovascular disease characterized by coronary artery blockage, inadequate blood supply, and subsequent ischemic necrosis of the myocardium, is one of the leading causes of death. The cellular, physiological, and pathological responses following MI are complex, involving multiple intertwined pathological mechanisms. Hypoxia-inducible factor-1 (HIF-1), a crucial regulator of hypoxia, plays a significant role in of the development of MI by modulating the behavior of various cells such as cardiomyocytes, endothelial cells, macrophages, and fibroblasts under hypoxic conditions. HIF-1 regulates various post-MI adaptive reactions to acute ischemia and hypoxia through various mechanisms. These mechanisms include angiogenesis, energy metabolism, oxidative stress, inflammatory response, and ventricular remodeling. With its crucial role in MI, HIF-1 is expected to significantly influence the treatment of MI. However, the drugs available for the treatment of MI targeting HIF-1 are currently limited, and most contain natural compounds. The development of precision-targeted drugs modulating HIF-1 has therapeutic potential for advancing MI treatment research and development. This study aimed to summarize the regulatory role of HIF-1 in the pathological responses of various cells following MI, the diverse mechanisms of action of HIF-1 in MI, and the potential drugs targeting HIF-1 for treating MI, thus providing the theoretical foundations for potential clinical therapeutic targets.

The skin of the naked mole-rat and its resilience against aging and cancer

The naked mole-rat (NMR) Heterocephalus glaber (from the Greek/latin words ἕτερος, heteros = divergent, κεφαλή, kephalē = head and glabra = hairless) was first described by Rüppell (Fig. 1) and belongs to the Hystricognath (from the Greek words ὕστριξ, hystrix = porcupine and γνάθος, gnathos = jaw) as a suborder of rodents. NMR are characterized by the highest longevity among rodents and reveal a profound cancer resistance. Details of its skin-specific protective and resistance mechanisms against aging and carcinogenesis have so far not been adequately characterized. Recently, our knowledge of NMR skin biology was complemented and expanded by published data using state-of-the art histological and molecular techniques. Here we review and integrate novel published data regarding skin morphology and histology of the aging NMR and the underlying mechanisms at the cellular and molecular level. We relate this data to the longevity of the NMR and its resistance to neoplastic transformation and discuss further open questions to understand its extraordinary longevity. In addition, we will address the exposome, defined as "the total of all non-genetic, endogenous and exogenous environmental influences" on the skin, respiratory tract, stomach, and intestine. Finally, we will discuss in perspective further intriguing possibilities arising from the interaction of skin with other organs.

The association of rs2233679 in the PIN1 gene promoter with the risk of Coronary Artery Disease in Chinese female individuals

BACKGROUNDS

Vascular atherosclerosis leads to various cardiovascular and cerebrovascular diseases. Nitric oxide (NO) promotes vasodilatation and prevents Coronary Artery Disease (CAD). Pin1 suppresses NO production by down-regulating the activity of endothelial nitric oxide synthase (eNOS). Whether the genetic polymorphisms of the PIN1 gene (encoding Pin1) are implicated in CAD deserves investigations in human beings.

METHODS

A total of 210 CAD patients and control individuals (all females) were enrolled, and their genotypes of rs2233679 (-667C/T, a key SNP in the promoter of PIN1 gene) were sequenced. T-test, chi-square test, odds ratio (OR) and 95% confidence interval (95% CI) were calculated to evaluate Hardy-Weinberg equilibrium, varied genetic distribution and relative CAD risk.

RESULTS

The differences in age, BMI, triglyceride, total cholesterol, low-density and high density cholesterol between the CAD and control groups were not significant (all P>0.05), and Hardy-Weinberg equilibrium was observed in the two groups (both P>0.05). The frequency of -667T allele in the CAD group was higher than that in the control group. The genotype -667TT elicited a higher hazardous risk of CAD compared to the genotype -667CC (OR=1.85, 95% CI: 0.75-4.53) as well as the genotypes CC+CT (OR=1.97, 95% CI: 0.86-4.49).

CONCLUSIONS

We firstly show that the allele -667T in the PIN1 promoter may elicit a higher CAD-risk than -667C, and the -667TT genotype of PIN1 may be a new genetic biomarker for increased incidence of CAD. These novel observations put forward a new understanding of the PIN1-CAD genetic relationship in humans, potentially contributing to both cardiovascular and cerebrovascular disorders.

Effects of hypoxia on cardiomyocyte proliferation and association with stage of development

BACKGROUND

Hypoxia has been suggested to be both beneficial and harmful to the proliferation of cardiomyocytes. This controversy remains unresolved, and the underlying mechanism by which hypoxia exerts its effects remains unclear. We here hypothesize that cardiomyocyte developmental stage may play a role.

METHODS AND RESULTS

The embryonic ventricular myocyte cell line H9C2, primary isolated fetal cardiomyocytes, and neonatal cardiomyocytes were cultured with normal O₂ (21% O₂) or under hypoxic conditions (10% O₂) for 7 days, and then harvested for Western blotting, qRT-PCR, and immunostaining. When cultured under hypoxic conditions, proliferating marker-Ki67, mRNA level, and the percentage of Ki67-positive cardiomyocytes were significantly lower in H9C2 and fetal cardiomyocytes but higher in neonatal cardiomyocytes. Consistently, the mRNA and protein levels and induced nuclear localization of yes associated protein 1(YAP1), one of the most important regulators of cardiomyocyte proliferation, were significantly lower in H9C2 and fetal cardiomyocytes but up-regulated in neonatal cardiomyocytes when treated with hypoxia. Compared to neonatal cardiomyocytes, there was a lower level of troponin T mRNA and protein expression in H9C2 and fetal cardiomyocytes. When H9C2 or fetal cardiomyocytes overexpressing troponin T in were cultured under hypoxic condition, their ability to proliferate increased.

CONCLUSIONS

The effect of hypoxia on the proliferation of cardiomyocyte is associated with their developmental stage. YAP1 expression is positively correlated with the change in cardiomyocyte proliferation in response to hypoxia. Developmental stage- specific sarcomere component troponin T may partly account for the underlying mechanism.