Cardiac regeneration has garnered substantial attention, with a central scientific question being the origin of newborn cardiomyocytes. Current research proposes potential sources, including the transdifferentiation from other cell types and the differentiation of progenitor cells, and dedifferentiation of pre-existing cardiomyocytes (Figure 1).

The zebrafish heart has an amazing ability to regenerate throughout its life, thanks largely to the fact that its cardiomyocytes never fully exit the cell cycle and are able to proliferate in response to signals of injury to replenish lost myocardium (8). Fate mapping studies in zebrafish heart regeneration have demonstrated that fish replace lost cardiomyocytes primarily through the proliferation of undifferentiated cardiac precursor cells. By utilizing an EGFP dual fluorescent reporter gene driven by the cmlc2 promoter, researchers successfully traced the origin of newborn cardiomyocytes. Prior to cardiac injury, all cmlc2-expressing cardiomyocytes were labeled by eGFP expression, and most regenerating tissues exhibited eGFP expression 30 days after ventricular resection. These findings indicate that the newborn myocardium is predominantly derived from progenitor cells that subsequently differentiate into proliferative cardiomyocytes (9, 10). In recent years, studies have shown that transdifferentiation also contributes to cardiac regeneration. For instance, Zhang et al. discovered that differentiated atrial cardiomyocytes can transdifferentiate into ventricular cardiomyocytes using a combination of genetic fate mapping mapping and ventricle-specific genetic ablation system in zebrafish models. Notably, inhibition of Notch signaling blocked atrial-to-ventricular transdifferentiation and impaired cardiac regeneration (11). In addition, Poss et al. utilized a lineage-tracing method to fluorescently label zebrafish cardiomyocytes, confirming that neonatal cardiomyocytes are derived from pre-existing ones (12).

The switching of growth patterns in the mammalian heart during cardiac maturation is tightly controlled. Thus, mammalian cardiomyocytes regenerated after neonatal injury are derived from pre-existing cardiomyocytes, utilizing their proliferative activity that has not been completely lost, rather than transdifferentiated or induced stem cells (13). For example, Koudstaal et al. found by gene genealogical tracing techniques that cardiomyocytes can replenish damaged myocardium by de-differentiating and re-entering the cell cycle after injury in the neonatal mouse heart (14). The viewpoint was further substantiated by investigations into neonatal rat heart regeneration (4).

Overall, these investigations not only provide compelling evidence for cardiac plasticity during myocardial injury but also reveal multiple potential sources of cardiac resident cells for cardiac regeneration.

Lower vertebrates demonstrate superior cardiomyocyte regeneration capabilities compared to mammals. Zebrafish have exhibited successful regeneration and functional recovery in various cardiac injury models, including apical resection (AR), cryoinjury, and genetic cell ablation (12, 15–18). Amongst low-vertebrate species, tailless amphibians are also renowned for their remarkable cardiac regeneration capabilities. Following cardiac injury in salamanders, complete restoration of cardiac function without scarring can be achieved within three months (19–21). Additionally, it has been observed that adult frog cardiomyocytes limited some proliferative capacity and the ability to dedifferentiate. However, scar tissue formation occurs after cardiac injury, preventing complete cardiac regeneration (22).

The most significant difference between mammals and lower vertebrates lies in their capacity to complete the cell cycle (23, 24). In contrast to haploid cardiomyocytes, polyploid cardiomyocytes exhibit restricted proliferative capacity and typically fail to progress through the normal cell cycle (25). Furthermore, it has been demonstrated that mononuclear diploid cardiomyocytes play a crucial role in cardiac regeneration and repair due to their substantial proliferative potential (26). Unlike zebrafish mononuclear cardiomyocytes, which can re-enter the cell cycle during adulthood, adult mammalian cardiomyocytes transition from proliferative mononuclear diploid cells to nonproliferating binucleated diploid cells either before (27) or shortly after birth (28), thereby limiting their proliferative capacity (28, 29). Whether diploid or polyploid cardiomyocytes possess proliferate capabilities during cardiac regeneration and contribute to myocardial repair, as well as offering therapeutic strategies remains an area requiring further investigation.

Unlike zebrafish, adult mammalian hearts exhibit limited cardiac regeneration following injury (30). However, studies of neonatal cardiac regeneration in mice have demonstrated robust regenerative responses in injured areas after AR and MI surgery (4, 31). These findings highlight a specific time window during which the mammalian heart displays a strong regenerative response immediately after birth. However, Robledo et al. reported that the rat heart fails to achieve complete regeneration when subjected to burn injury 4–7 days after birth, underscoring the need for further investigation into the mechanisms underlying the differences in regenerative capacity between neonatal rats and mice (32). Interestingly, AR surgery performed on mice seven days after birth did not trigger a significant regenerative response (4), indicating that the heart's regenerative potential significantly diminishes shortly after birth. Recent reports on neonatal corrective cardiac surgery (33) and neonatal MI (34) suggest that human neonates may possess a higher regenerative capacity, enabling them to recove cardiac function effectively.

In the context of cardiac regeneration, lower vertebrates such as zebrafish exhibit complete restoration of the heart following injury, whereas mammals lose this regenerative capacity shortly after birth. Thus, what factors restrict cardiomyocyte proliferation, thereby reducing the regenerative potential in mammals? Consequently, elucidating the regulatory mechanisms that govern cardiomyocyte proliferation and identifying key regulators that orchestrate cardiac regeneration remain crucial objectives in cardiac regeneration research.

Overall, there are significant differences in the origin of neonatal cardiomyocytes and the regenerative capacity of the heart between lower vertebrates and mammals. Nevertheless, these studies provide an important theoretical foundation for the advancement of cardiac regenerative medicine. The development of cardiac regenerative medicine will emphasize multidisciplinary collaboration and innovation, integrating cell therapy, gene therapy, tissue engineering, and biomaterials to achieve effective treatment after MI. Future research will need to further optimize these techniques, address existing challenges, and facilitate the broader application of regenerative medicine in MI treatment.

In recent years, a multitude of coding genes that regulate the cell cycle in cardiac regeneration have been identified by researchers. These factors arrest the cardiomyocyte cell cycle through diverse pathways, thereby blocking both cardiomyocyte proliferation and cardiac regeneration (51).

Certain cell cycle regulators can suppress the proliferation of cardiomyocytes by directly binding to Cyclin or indirectly activating CDKs. For instance, the transcription factor E2F interacted with Cyclin to regulate both the proliferation and differentiation of cardiomyocytes (52). Deletion of E2F1, E2F2, and E2F3 has been shown to prevent cells from entering the S phase, thereby arresting the cell cycle of cardiomyocytes and inhibiting their capacity for proliferation (53). In 2013, Sadek et al. discovered that a transcription factor Meis1 played a crucial role in preventing heart muscle cells from dividing (54). Initially thought to act alone by Sadek's team during early studies where they knocked out its encoding gene in mice resulting in prolonged window for neonatal mouse cardiomyocyte division. However this prolongation was short-lived as these deficient cardiomyocytes eventually slowed down their division and ceased proliferating (54). Subsequently identified was Hoxb13 as a chaperone protein for Meis1; when both Meis1 and Hoxb13 were knocked out together in mice models it caused regression of cardiomyocytes back to an earlier developmental stage characterized by decreased size but increased number (54). Furthermore, they found that the CDK inhibitors p15, p16, and p21 are essential for transcriptional activation of Mesi1 as its transcriptional activation targets (55).

A study by Velayutham et al. revealed that the expression patterns of transcriptional co-regulators Btg1 and Btg2 during neonatal mouse cardiac development were consistent with the observed pattern of cell cycle of cardiomyocytes arrest. Btg1/2 constitutive double knockout cardiac tissues exhibited an increase in pH3⁺ mitotic cardiomyocytes at P7 but not at P30 (56). This finding indicates that suggest that Btg1 and Btg2 are novel factors involved in postnatal cell cycle of cardiomyocytes arrest. Zinc finger transcription factors are closely associated with cardiomyocyte proliferation. Mohammadi et al. demonstrated that specific knockdown of GATA4 in cardiomyocytes was found to reduce cardiomyocyte proliferation and myocardial angiogenesis in a rat model of cryoinjury, suggesting impaired cardiac regenerative capacity (57). CBX7 levels in the heart exhibit a continuous increase after birth and persist throughout adulthood. Overexpression of CBX7 in neonatal mouse cardiomyocytes has been shown to inhibit proliferation and promote multinucleation (58).

Secreted factors play important roles in cardiomyocyte cycle arrest and cardiac regeneration. Yang et al. identified omentin-1 as an adipokine that directly interacts with bone morphogenetic protein 7 (BMP7), regulating cardiomyocyte maturation. Omentin-1 prevents BMP7 from binding to activin type II receptor B (ActRIIB), subsequently inhibiting downstream signaling pathways involving DPP homolog 1 (SMAD1)/yes-associated protein (YAP) and p38 mitogen-activated protein kinase (p38 MAPK) (59). In another study, p38α negatively regulated adult zebrafish cardiomyocyte proliferation (60). Interestingly, Wu et al. showed that endogenous BMP signaling in zebrafish induced cell cycle arrest, thereby attenuating cardiomyocyte dedifferentiation and ultimately impairing myocardial regeneration (61). In a zebrafish regeneration model study, deficiency of histone deacetylase 1 (Hdac1) was found to affect the Cdc25-Cdk1 cell cycle axis, resulted in impaired progression through the G2/M phase and Cell cycle of cardiomyocytes arrest (62). Periostin, a secreted extracellular matrix protein, induces reentry into the cell cycle of already differentiated cardiomyocytes through the PI3K pathway, reduces post-infarction fibrosis, decreases infarct size, promotes angiogenesis and improves cardiac function (63). In addition, Chen et al. showed that Periostin mediates cardiomyocyte proliferation after myocardial infarction through PI3K/AKT/GSK3β signaling (64). NRG1, an epidermal growth factor, stimulates cardiomyocytes to re-enter the cell cycle and divide by activating downstream signaling pathways through its receptors ErbB2, ErbB3, and ErbB4 (65). However, although NRG1 transiently activates ErbB receptors to promote cardiomyocyte proliferation, it may inhibit overproliferation in adult myocardium through a negative feedback mechanism (66). Fibroblast growth factor FGF belongs to the family of secreted proteins. Studies have shown that activation of the FGF signaling pathway promotes cardiomyocyte proliferation and hypertrophy. For example, FGF10 regulates cell cycle reentry in cardiomyocytes by interacting with FGFR2b (embryonic stage) and FGFR1b (adult stage), thereby increasing ventricular wall thickness (67). However, chronic activation of the FGFR1 signaling pathway leads to cardiomyocyte hypertrophy and cardiac remodeling as evidenced by increased cardiomyocyte cross-sectional area, interstitial fibrosis, and disturbed myocyte alignment (68). In summary, secreted factors regulate cardiomyocyte cycle arrest through a complex network, a property that maintains cardiac homeostasis while limiting regenerative capacity. Future studies need to further resolve the spatiotemporal-specific roles of specific factors under pathological/physiological conditions to develop targeted intervention strategies.

Manipulating factors that induce cell cycle arrest during cardiac growth and development to influence cardiomyocyte proliferation, thereby promoting cardiac regeneration and repair, is anticipated as a prospective therapeutic strategy for cardiac restoration.

In recent years, an increasing number of evidence has demonstrated the involvement of noncoding RNAs (ncRNAs) in cardiac regeneration and their key roles in the pathogenesis of various CVDs. Specifically, circular RNAs (circRNAs) have emerged as crucial drivers of Cell cycle of cardiomyocytes arrest during adulthood. The Meis1-driven expression of circNfix exerts an inhibitory effect on cardiomyocyte proliferation. circNfix promoted the ubiquitin-dependent degradation of Y-box binding protein 1 (Ybx1), thereby suppressing the expression of Yap1 target genes Cyclin A2 and Cyclin B1, resulting in the inhibition of cardiomyocyte proliferation (69). Silencing of circMdc1 induced by oxidative stress allows reentry into the cell cycle of cardiomyocytes (70). Moreover, by competitively binding to proteins required for translation of its host gene, Mdc1, circMdc1 influenced oxidative DNA damage and controlled the window for cardiomyocyte cell cycle progression (70). In our previous work, we verified that circNCX1 plays a role in regulating cardiomyocyte proliferation by negatively regulating ubiquitination of the transcriptional activator BRG1 (71). The cyclic insulin circlGFIR interacted with miR-5-362p in the adult heart to inhibit cardiomyocyte proliferation, providing a crucial experimental basis for cardiac regeneration regulation (72). Long noncoding RNAs (lncRNAs) play a pivotal role in maintaining cellular homeostasis. Wang et al. discovered that the lncRNA CPR was an effective repressor of cardiomyocyte proliferation, offering a potential lncRNA-based therapeutic target for cardiac repair and regeneration (73). Furthermore, lncRNAs CAREL, CRRL, and AZIN2-sv have been shown to inhibit cardiomyocyte proliferation by interacting with micro RNAs (miRNAs) (74–76). MiRNAs are crucial regulators in cardiac development and involved in modulating various CVDs. In hearts of rats with MI, 85 differentially expressed miRNAs were identified, among which miR-30b-5p was down-regulated. Treatment of its inhibitor enabled reentry into the Cell cycle of cardiomyocytes while inhibiting cardiomyocyte apoptosis (77). Furthermore, cardiac-specific overexpression of miR-128 impaired cardiomyocyte proliferation and cardiac function, whereas miR-128 deletion inhibited p27 expression by enhancing SUZ12 expression, which further activated Cyclin E and CDK2 and contributed to cardiomyocyte cycle re-entry (78). The miR-15 family plays an important negative regulatory role in cardiomyocyte proliferation and cardiac regeneration. It has been shown that miR-15 family members (e.g., miR-195) are upregulated in the postnatal heart and promote cardiomyocyte proliferative arrest by repressing the expression of the cell cycle-associated gene Chek1 (79). chek1 plays a critical role in the G2/M phase transition and mitotic progression, and its expression is inhibited by the miR-15 family, leading to cardiomyocyte proliferation arrest (79). Meanwhile, the proliferative capacity of adult cardiomyocytes could be activated by inhibition of miR-15 family members and improved cardiac function in a myocardial infarction model (80). Thus, by inhibiting miR-15 family members, the proliferative capacity of cardiomyocytes can be activated, thus providing a new strategy for cardiac regeneration. These findings provide an important theoretical basis for the development of miRNA-based therapies for cardiac regeneration.

Collectively, these findings suggest that targeting ncRNA molecules holds great promise as a therapeutic strategy to promote cardiac repair processes and provides valuable insights for further investigations into the molecular mechanisms underlying cardiac regeneration.

The adult heart primarily derives its energy from the oxidation of fatty acids (109). Among all energy substrates, fatty acids produce the highest amount of ATP per 2 carbon units but also have the greatest oxygen demand. Consequently, fatty acids are considered the least metabolically efficient cardiac energy substrate in terms of total ATP produced/oxygen consumed (110).

Studies have shown that inhibition of fatty acids promotes cardiomyocyte proliferation and cardiac regeneration (111, 112). Neonatal mice fed with fatty acid-deficient milk exhibited an extended postnatal window for cardiomyocyte proliferation, but eventually progressed to cell cycle arrest (111). Carnitine palmitoyltransferase 1 (CPT1), a crucial enzyme in fatty acid oxidation, plays an indispensable role in regulating the metabolic switch from glycolysis to fatty acid oxidation. Li et al. demonstrated that inactivation of the b-type subunit of CPT1 (CPT1b) abolished fatty acid oxidation in cardiomyocytes, inducing a transition from a mature to an immature metabolic state and thereby reversing cardiomyocyte cell cycle arrest (112). Furthermore, etomoxir (ETO), an inhibitor of CPT1 activity, was found to suppress fatty acid oxidation and stimulate cardiomyocyte proliferation and cardiac regeneration in neonatal mice (113). Inhibition of carnitine palmitoyltransferase 2 (CPT2), another key enzyme in fatty acid oxidation, promoted cardiomyocyte proliferation in 2-week-old mice (114). Acyl coenzyme A synthetase long-chain family member 1 (ACSL1) is an essential regulator of lipid metabolism. Its expression level progressively increases after birth. Knockdown of ACSL1 significantly enhanced cardiac regeneration in primary mouse cardiomyocytes and efficiently restored cardiac function and muscle regeneration in adult mice following MI (115).

Phosphatidic acid plays a crucial role in lipid anabolism. Cao et al. unveiled the involvement of sphingolipid metabolism in cardiac regeneration, where SphK1 and SphK2, the two isozymes responsible for producing sphingosine-1-phosphate, exhibiting contrasting roles in repairing neonatal cardiac injury (116). Therefore, it is reasonable to speculate that ketoester metabolism also plays an indispensable role in regulating cardiac regeneration. Taken together, targeting fatty acid utilization in cardiomyocytes enhances proliferation and represents a promising therapeutic target for cardiac regenerative therapies (Table 1).

Glucose serves as a crucial energy source in the heart, where ATP production occurs through cytoplasmic glycolysis and mitochondrial oxidation of pyruvate derived from glycolysis. Glucose enters cardiomyocytes via glucose transporter protein 1 (GLUT1), where it is phosphorylated by hexokinase (HK) and subsequently participates in various metabolic processes. GLUT1 functions primarily as a glucose transporter protein in mammalian embryonic and neonatal hearts (117). Overexpression of GLUT1 in neonatal mouse hearts has been shown to enhance glycolytic efficiency (118) and facilitate cardiac regeneration following cryoinjury (119). These findings provide novel evidence supporting the notion that elevated expression of GLUT1 promotes cardiomyocyte proliferation and cardiac regeneration through enhanced glycolysis.

Key components of glycolysis are involved in the regulation of myocardial regeneration. Phosphofructokinase2 (PFK2), an essential enzyme in glycolysis, has been shown to enhance cardiomyocyte contractility when overexpressed in hypoxic mice (120), suggesting its potential cardioprotective function following cardiac injury. Pyruvate dehydrogenase kinase (PDK), another significant enzyme involved in glycolysis, exhibits significantly increased expression during cardiac development and further upregulation in adult hearts (121), consistent with the pattern of postnatal cardiomyocyte cell cycle arrest. Moreover, both zebrafish cryoinjury and mammalian MI models demonstrate substantial upregulation of PDK within the infarct zone (122, 123). Interestingly, overexpression of PDK3 promotes cardiomyocyte proliferation following zebrafish cardiac cryoinjury, but fails to influence scar repair (122). In contrast, cardiac-specific deletion of PDK4 facilitates cardiomyocyte proliferation and cardiac repair in the injured region after MI by enhancing glycolysis (124). Notably, as isoenzymes of PDK3 and PDK4 exhibit opposing roles in cardiac repair. This discrepancy may be attributed to their distinct distribution patterns, necessitating further investigation into the underlying mechanisms. The rate-limiting enzyme in the final step of glycolysis, pyruvate kinase muscle isoform 2 (PKM2), shows high expression levels in embryonic and neonatal mouse hearts. Overexpression of PKM2 promotes adult cardiomyocyte proliferation and myocardial regeneration by increasing glucose-6-phosphate dehydrogenase expression (125). Deletion of PKM2 inhibits glycolysis and reduces cardiomyocyte proliferation in zebrafish (126). Therefore, targeting specific glycolytic enzymes represents a promising therapeutic strategy for promoting cardiac repair and regeneration.

Collectively, these studies indicate that glycolysis plays a crucial role in regulating cardiomyocyte proliferation and cardiac regeneration following injury. Consequently, targeting glucose metabolism to reverse cardiomyocyte cell cycle arrest emerges as an efficacious strategy for promoting adult cardiac regeneration.

The postnatal transition from glycolysis to fatty acid oxidation as the primary energy source in mammals is accompanied by a significant increase in mitochondrial abundance, which results in elevated levels of ROS during this period. The increased ROS levels subsequently induce DNA damage, leading to cell cycle arrest in cardiomyocytes (6). Therefore, understanding the role of mitochondrial metabolites in regulating this metabolic switch is crucial for developing research strategies focused on metabolic targeting for adult cardiac regeneration.

On one hand, inhibition of mitochondrial metabolism in cardiomyocytes leads to the reversal of cardiomyocyte cell cycle arrest. Succinate dehydrogenase (SDH) serves as a crucial link between the TAC and oxidative phosphorylation, playing a crucial role in cell cycle regulation and metabolic reprogramming (127). A study demonstrated that malonate-induced inhibition of SDH extended the window for cardiomyocyte proliferation in juvenile mice and promoted cardiomyocyte proliferation, hypertrophy, and cardiac regeneration in adult mice with MI. Notably, this inhibition was accompanied by an enhancement of glucose metabolism and a reduction in TAC cycle metabolism (128), consistent with the metabolic reprogramming process observed during the shift from oxidative phosphorylation to glycolysis in the adult heart, which facilitates cardiomyocyte proliferation and cardiac regeneration.

On the other hand, inhibition of oxidative pathways during mitochondrial metabolism leads to a reduction in ROS production. Martin et al. discovered that activation of antioxidant responses decreased ROS production and facilitated repair following cardiac injury (129). Sadek et al. reported that overexpression of mitochondrial peroxidase (mCAT) and the ROS scavenger, N-acetylcysteine (NAC) system, reduced DDR and promoted cardiomyocyte proliferation (6). Ge et al. demonstrated that Pitx2 deficiency failed to restore neonatal mouse hearts with AR due to the activation of genes associated with ROS scavenging by Pitx2 expression (129). Pei et al. demonstreated that the antioxidant hydrogen sulfide (H₂S) eliminated ROS and reversed cardiomyocyte cell cycle arrest. Conversely, propylglycine (PAG), an inhibitor of H₂S synthesis, was found to accumulate ROS, thereby suspending cardiomyocyte proliferation and cardiac regeneration in neonatal mice (130). In contrast, administration of NAD⁺ (NaHS), a hydrogen donor, attenuated H₂S-mediated ROS accumulation and improved cardiac regeneration through enhanced cardiomyocyte proliferation and elimination of ROS after MI in P7 mice (130). These findings unveil a protective mechanism aimed at reducing mitochondrial oxidative stress-induced cardiomyocyte cell cycle arrest while providing a novel therapeutic strategy for HF.

The mitochondrial pyruvate carrier (MPC), located on the inner mitochondrial membrane, is responsible for transporting pyruvate from the cytoplasm to the mitochondrial matrix, where it participates in the tricarboxylic acid cycle, gluconeogenesis, and metabolism of lipids and amino acids to provide energy for the organism. The MPC plays a key role in the proliferation of cardiomyocytes and in the regulation of the cell cycle. Studies have shown that MPC1 deficiency leads to cardiomyocyte hypertrophy and heart failure, whereas MPC1 overexpression attenuates the hypertrophic response of cardiomyocytes (131). In addition, drugs modulating MPC activity may promote cardiomyocyte survival and functional recovery by improving energy metabolism and antioxidant capacity of cardiomyocytes. Currently, the MPC inhibitor UK5099 has been used to investigate its therapeutic potential in metabolic diseases (132), so could drugs modulating MPC activity further influence the cell cycle by regulating the metabolic level of cardiomyocytes, which could ultimately be applied in the clinical treatment of cardiovascular diseases such as MI?

Taken together, these studies provide compelling evidence for the crucial role of mitochondrial metabolites in modulating cardiac metabolism and highlight their promising therapeutic potential in facilitating adult cardiac regeneration (Table 1).

Proteins play a pivotal role in the growth and maturation of cardiomyocytes, with enhanced protein synthesis leading to increased amino acid metabolism. To gain further insights into the involvement of amino acid oxidation in cardiac regeneration, studies have primarily focused on branched chain amino acids (BCAAs), namely leucine, isoleucine, and valine. BCAA levels exhibited dynamic fluctuations during mouse heart development. Specifically, valine, leucine, and isoleucine showed an increase during the postnatal phase, reaching a peak at day 9, followed by a decline in adulthood. Furthermore, most of the differentially expressed genes is directly associated with BCAA concentrations (133), indicating that amino acid metabolism plays an essential role in cardiomyocyte maturation. Therefore, we hypothesized that inhibiting enzymes involved in the catabolic pathway of BCAAs can enhance cardiomyocyte proliferation.

The mammalian target of rapamycin (mTOR) signaling pathway plays a critical role in cardiac development and growth (134, 135). Increased expression of glutamine, an amino acid transporter, in zebrafish and neonatal mouse cardiomyocytes activates the mTOR signaling pathway and regulates cardiomyocyte proliferation. Moreover, high concentrations of leucine and glutamine have been found to activate mTOR signaling and facilitate cardiac regeneration (136). Therefore, it is worth investigating whether the concentration of BCAAs also impacts the proliferative capacity of cardiomyocytes. Previous study has demonstrated that BCAAs activate the mTOR signaling pathway and induce metabolic reprogramming from fatty acid oxidative metabolism to glycolysis via HIF-1α (137), which is consistent with the metabolic reprogramming observed during cardiac regeneration. Conversely, inhibition of mTOR signaling blocks cardiac regeneration in zebrafish and promotes maturation of human pluripotent stem cell (iPSC)-derived cardiomyocytes (138, 139). Thus, it is evident that cardiomyocyte amino acid metabolism influences both cardiomyocyte proliferation and cardiac regeneration. However, further comprehensive investigations are warranted due to limited findings in this research area.

In summary, the blockage of metabolic regulatory mechanisms of the cardiomyocyte cycle represents an important research direction in cardiac regenerative medicine. Future studies will explore the regulatory mechanisms of cardiomyocyte regeneration in depth through metabolic intervention, epigenetic regulation, and multi-omics technology, thereby providing new strategies and methods for the treatment of cardiac diseases.

Myocardial energy metabolism plays a crucial role in regulating various pathological processes of CVDs, and interventions targeting myocardial energy metabolism hold promise as the next frontier for CVD prevention and treatment (140, 141).

Trimetazidine is used as an adjunct in the clinical treatment of HF to protect cardiomyocyte energy metabolism under hypoxic or ischemic conditions by reducing fatty acid beta oxidation and promoting glucose metabolism. In rat heart following I/R injury, trimetazidine has been shown to inhibit excessive glycolysis and enhance aerobic glucose oxidation (142). Consequently, trimetazidine exerts favorably influences the regulation of cardiomyocyte cell cycle through modulation of energy metabolism in the injured myocardium. Mitochondria, as the primary site of energy metabolism, have made the development of drugs targeting mitochondrial function regulation a major focus in the treatment of CVDs (143, 144). CoQ10, a naturally occurring compound in the human body closely associated with cardiac energy metabolism, exhibits notable antioxidant properties and effectively reduces the risk of cardiac morbidity (145). Nicotinamide adenine dinucleotide (NAD⁺), also known as coenzyme I, is a crucial central metabolite involved in redox reactions (146). Evidence from animal experiments has demonstrated that NAD⁺ levels are downregulated following cardiac I/R injury, and NAD+ supplementation reduces infarct size while reversing cardiomyocyte cell cycle arrest by regulating metabolic reprogramming (147–151). In recent years, NAD⁺ mediated myocardial metabolic disorders have been recognized as one of the pathogenic mechanisms underlying CVDs. Therefore, exploring the pharmacological role of NAD⁺ holds great promise as a therapeutic avenue.

Enhancing the energy supply through metabolism-related pathways plays a beneficial and complementary role in CVD treatment. Meanwhile, ensuring the judicious and rational utilization of myocardial metabolism-targeted drugs to maintain the homeostasis of energy metabolism represents a crucial next step in CVD drug discovery and development.

As ongoing research progresses, an increasing number of evidence indicates that ncRNAs play a crucial role as regulatory molecules in modulating the cardiomyocyte cell cycle (152). In recent years, the development of multiple RNA-based therapies has further accelerated advancements in ncRNA-targeted drug discovery and development.

MiRNAs have emerged as promising targets for novel CVD-targeted therapeutics due to their short length, strong conservation, and high stability (153, 154). Currently, CDR132l, an antisense oligonucleotide drug targeting miR-132, has become the first therapeutic drug for HF and entered clinical trials. In a porcine model of HF after MI, CDR132l demonstrated significant improvements in HF severity, restoration of cardiomyocyte function, and reversal of cardiomyocyte cell cycle arrest within a reasonable dosage range (155). MRG-110, an antisense oligonucleotide drug for the treatment of cardiovascular diseases, promotes the growth of new blood vessels by inhibiting miR-92a, thereby exerting a therapeutic effect in accelerating wound healing (156). However, its clinical studies related to CVDs remain limited. Collectively, miRNA-based drugs hold promising prospects for treating MI and promoting myocardial cell cycle recovery following ischemic injury, thus representing novel biological targets worthy of further exploration in CVD treatment.

In comparison to miRNAs, lncRNAs and circRNAs have received relatively less attention in the field of CVD drug discovery and development owing to their limited in vivo stability, larger molecular size, and propensity to induce an immune response. Therefore, overcoming these challenges represents the subsequent crucial step for drug developers.

In summary, cell cycle regulation and metabolic regulation are important in the treatment of cardiovascular diseases. Future research will develop more effective and safer therapeutic drugs and methods through targeted therapy, nucleic acid-based therapeutic strategies, metabolic interventions, and clinical translation, providing new hope for the treatment of cardiovascular diseases.