Plant-derived hydrogel and photosynthetic nano-units for myocardial infarction therapy

Lv, YongBo; Zhu, Dashuai; Li, Junlang; Li, Yuan; Lu, Chao; Bi, Jianing; Huang, Ke; Hu, Shiqi; Liu, Shuo; Yan, Na; Cheng, Ke; Wang, Juan

doi:10.1038/s41467-025-62020-5

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Published: 18 August 2025

Plant-derived hydrogel and photosynthetic nano-units for myocardial infarction therapy

Nature Communications volume 16, Article number: 7678 (2025) Cite this article

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Abstract

Ischemic injury and reperfusion injury collectively determine the total infarct size, a major prognostic factor following myocardial infarction (MI). Therefore, addressing both ischemic and reperfusion stages could substantially reduce infarct size and improve clinical outcomes. In this study, we develop a two-component therapeutic system from different parts of Glycyrrhiza: a functional hydrogel made from glycyrrhizic acid extracted from the stem and root, and nanosized chloroplast units (NCUs) derived from leaves. The hydrogel demonstrates therapeutic effects during both hypoxia and reoxygenation stages in vitro, while the photosynthetic NCUs alleviate hypoxia injury by providing ATP and NADPH under illumination. Subsequent in vivo study reveals the most significant therapeutic effect in the combination group (NCU plus hydrogel), which effectively treats both ischemic and reperfusion stages. Our study highlights the cross-species application of plant photosynthetic mechanisms in MI treatment and confirms that simultaneous treatment of ischemia and reperfusion is more effective than treating either stage alone, offering a promising therapeutic strategy for MI.

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Introduction

Despite an increasing number of new drugs and interventional devices have been developed for treating myocardial infarction (MI), the morbidity and mortality of ischemic heart disease remain substantial worldwide¹. Clinical trials have demonstrated that myocardial infarct size is a major determinant of patient prognosis², therefore, developing new strategies to minimize infarct size is a very meaningful and promising direction. Infarct size is composed by ischemic injury and reperfusion injury, longer ischemic time causes a larger infarct size, so timely reperfusion is the primary therapeutic goal in clinical practice. However, reperfusion can itself induce additional injury, further exacerbating infarct size³. Therefore, identifying strategies to address both ischemic and reperfusion injuries, particularly the ischemic injury, which predominantly contributes to infarct size³, could substantially reduce infarction.

At the molecular level, ATP depletion is an initiating factor for ischemic injury, resulting from reduced or complete cessation of blood supply⁴. As for reperfusion injury, the excessive formation of reactive oxygen species (ROS) is one of the trigger factors⁴. Previous study found the nanosized plant-photosynthetic-units can produce ATP and NADPH in mammalian cells⁵, which happen to be suitable for treating ischemic and reperfusion injuries. The ATP production can supplement ATP depletion that occurred at the ischemic stage, while the reductive NADPH can neutralize excessive ROS that generated at the reperfusion stage. Inspired by this, we aim to develop a plant-derived therapeutic system and realize cross-species application for the treatment of MI.

We chose the herb Glycyrrhiza as a candidate plant in our study. Glycyrrhizic acid (GA), typically extracted from the stem and root of glycyrrhiza, shows protective effects against cardiac ischemia/reperfusion(I/R) injury⁶ and can be assembled into a hydrogel in PBS buffer⁷. Based on the above information, a two-component therapeutic system was established using different parts of glycyrrhiza. The first component is a functional hydrogel made from stem/root-derived GA, and the second is nanosized chloroplast units (NCUs) derived from leaves. This therapeutic system, which combines NCU with GA hydrogel, treated both cellular hypoxia injury and reoxygenation injury under light conditions. Its efficacy was further verified in the rat I/R model through intrapericardial injection. Intrapericardial injection is an effective drug-administration route for heart disease^8,9,10 and holds substantial value for clinical translation^11,12. Since all therapeutic components derive from glycyrrhiza and the system works under lighting, it is like “planting a glycyrrhiza in the heart”, after the process of photosynthesis, the grown-up glycyrrhiza provides a shelter for cardiac recovery.

Results

Fabrication and characterization of GA hydrogel

The GA hydrogel was formed in DPBS buffer through a simple ultrasonic dispersion followed by heating to obtain a homogeneous solution and subsequently cooled to room temperature (Fig. 1a). Gelation tests revealed that the concentration of 5 mM GA was a mixture of gel and solution, while 8 mM was too high to dissolve completely (Fig. 1b). In contrast, concentrations of 5.5 mM, 6 mM and 7 mM were identified as optimal for gelation, forming a complete gel state (Fig. 1b and Supplementary Fig. 1).

The biocompatibility of the hydrogel was assessed by coculture with rat heart-derived H9C2 cells for 72 h. The concentration of 5.5 mM, 6 mM and 7 mM hydrogels demonstrated no cytotoxicity compared to equal volume of DPBS buffer (Fig. 1c). Notably, hydrogels at concentrations of 5.5 mM and 6 mM enhanced cell viability after 48 h of coculture (Fig. 1c). We finally selected the 6 mM hydrogel as our standard sample and characterized its loose and porous structure using Scanning electron microscopy (SEM) (Fig. 1d). To determine the toxic dose of the 6 mM hydrogel, the volume of added-hydrogel was incrementally increased from 40 μL to 80 μL. The GA hydrogel enhanced cell viability again at a volume of 40 μL, while a volume of 70 μL (46.6% of the total volume) began to exhibit cytotoxicity (Supplementary Fig. 2).

The degradation behavior of the 6 mM hydrogel in vivo was investigated by injecting 100 μL of the hydrogel into the pericardial cavity of SD rats and monitoring its degradation at sequential time points (days 1, 3, 7, and 14). The results showed that the hydrogel remained detectable in the pericardial cavity for over 7 days, and by day 14, complete degradation was observed without significant immune cell infiltration, confirming its biodegradability and biocompatibility (Supplementary Fig. 3).

To evaluate the flow and deformation properties of the 6 mM hydrogel, rheological tests were conducted at 37 °C. The strain-sweep test identified the gel-to-solution point is 5.22% (Fig. 1e). When the strain exceeded 5.22%, the loss modulus (G”) was higher than the storage modulus (G’), indicating the transition from gel to solution state (gel state: G’ > G”, solution state: G’ < G”). In step-strain test, the hydrogel was firstly subjected to a low strain of 0.1%, where G’ > G”, indicating the sample maintained its gel state; secondly, a higher strain of 15% was applied on, G’ dropped significantly below G”, showing the hydrogel ruptured into solution; after that, the high strain was removed and the low strain of 0.1% applied again, the sample quickly recovered to its gel state (Fig. 1f). These results demonstrated that 6 mM hydrogel had strong deformability and recovery capabilities. Frequency-sweep and time-sweep tests further confirmed the hydrogel could sustain its gel state across this wide range of frequency changes and time span (Fig. 1g, h).

Establishment of hypoxia/reoxygenation (H/R) model and the effect of GA hydrogel on reducing H/R injury

To evaluate the therapeutic effect of GA hydrogel in vitro, a cellular H/R injury model was established based on the issued guideline¹³. Briefly, H9C2 cells were initially cultured in substrate-free medium and oxygen-free environment to induce hypoxia injury, after that the culture condition was replaced with complete growth medium and normal oxygen levels to create reoxygenation injury (Fig. 2a). Compared to normal control, 6 h of hypoxia (H6/R0) resulted in significant cell death, and the reoxygenation further exacerbate this, especially for 2 h of reoxygenation (H6/R2), which caused the largest amount of cell death (Fig. 2b, c). The marginal area of the field of view also showed the same trend (Supplementary Fig. 4). These results confirmed the successful establishment of the cellular H/R model, which will be utilized in subsequent experiments.

**Fig. 2: GA hydrogel alleviates cellular hypoxia and reoxygenation injuries.**

Lactate dehydrogenase (LDH) release was chosen as an indicator for measuring cellular injury in this study. After 6 h of hypoxia, H6/R0 group showed a higher LDH concentration than normal control, while the intervention of GA hydrogel (20 μL to 40 μL) reduced it and the therapeutic effect appears to display dose-dependent manner (Fig. 2d). During 2 to 8 h reoxygenation (H6/R2 to H6/R8), the hydrogel demonstrated its dose-dependent therapeutic effect again (Fig. 2e–h). The plot of LDH variation during reoxygenation found the interval between H/R (red) and H/R + Gel (green) increased with time (Fig. 2i). Further analysis of LDH reduction between them (H/R + Gel minus H/R) revealed that the longer interventional time leads to a larger LDH reduction (Fig. 2j), which means the hydrogel reduced cellular reoxygenation injury in a time-dependent manner.

GA hydrogel reduces H/R-induced ROS generation and cell death

Previous study found GA can inhibit ROS generation¹⁴, we speculate the GA hydrogel may have the same effect on reducing H/R-induced ROS generation. Two time points, 6 h of hypoxia (H6/R0) and 2 h of reoxygenation (H6/R2), were selected as standard conditions to induce hypoxia and reoxygenation injuries, respectively. Compared to normal control, the mitochondrial ROS (red) significantly increased in H6/R0 and H6/R2 groups, while the intervention of hydrogel decreased them (Fig. 3a, b). As glutathione synthetase (GSS), glutathione peroxidases-1 (GPX1), and Superoxide Dismutase 2 (SOD2) are important enzymes for eliminating mitochondrial ROS¹⁵, we presume the hydrogel may eliminate ROS through regulating these enzymes. Western blots found that the GSS and GPX1 were downregulated in H6/R0 (Fig. 3c) and H6/R2 (Fig. 3e) groups, while the intervention of hydrogel rectified them (Fig. 3d, f). In contrast, SOD2 was upregulated in H6/R0 and H6/R2 groups compared to normal control, which may be a compensatory response to defend excessive ROS derived from H/R injury. The intervention of hydrogel showed minimal effect on SOD2 expression when compared to H/R groups (Fig. 3d, f).

Given that the hydrogel can mitigate H/R-induced cellular injury and ROS generation, we sought to investigate its impact on cell death. Firstly, the therapeutic effect was observed under a light microscope. Compared to normal control, there were lots of white dots (floating dead cells) in H6/R0 and H6/R2 groups, while the hydrogel treatment reduced them (Fig. 3g and Supplementary Fig. 5). Then, the western blot was conducted to verify its therapeutic effect on protein level. Compared to normal control, the cleaved-caspase 3 was highly expressed in H6/R0 (Fig. 3h) and H6/R2 (Fig. 3i) groups, indicating the occurrence of apoptosis, while the hydrogel intervention significantly reduced cell apoptosis (Fig. 3j).

GA hydrogel can prevent intrapericardial injection-associated infection

Staphylococcus aureus (S. aureus) is not only the prevalent pathogen in surgical site infection¹⁶, but also a leading cause of purulent pericarditis¹⁷. Purulent pericarditis is a rare but severe disease, which often causes death if left untreated¹⁸. Intrapericardial injection is an invasive procedure, it may lead to S. aureus-induced purulent pericarditis. If the risk of infection can be reduced, intrapericardial injection could be more applicable.

A previous study found GA possesses some antibacterial ability¹⁴. In this study, we chose gram-positive S. aureus and gram-negative Escherichia coli (E. coli) to evaluate the antibacterial ability of GA hydrogel. The optical density at 600 nm (OD600), which increases with bacterial proliferation, was employed to monitor bacterial growth. Compared to 0.75 mM and 1.5 mM GA, the concentration of 3 mM shown inhibitory effect on S. aureus growth, restraining S. aureus at a very low level during 12 h incubation (Supplementary Fig. 6a). Even more pronounced inhibition was observed with 6 mM and 12 mM GA hydrogel concentrations (Supplementary Fig. 6a). The value of OD600 among different concentration groups revealed a dose-dependent inhibitory effect on S. aureus (Supplementary Fig. 6b). After 12 h treatment with GA hydrogel, the remaining bacteria were cultured on agar plates for recultivation (Supplementary Fig. 6c). Compared to DPBS, 6 mM hydrogel almost eradicated S. aureus. As for E. coli, 6 mM and 12 mM hydrogel exhibited some antibacterial ability, but it’s not enough to significantly inhibit E. coli growth (Supplementary Fig. 6d–f).

Fabrication and characterization of NCU

The green leaves of glycyrrhiza were harvested to isolate chloroplasts (Fig. 4a). The particle size of intact chloroplasts was about 5.56 μm (Fig. 4b). After extruding through a series of porous membranes, the intact chloroplasts fragmented into NCUs. The particle size of NCUs were around 153 nm, and the transmission electron microscopy (TEM) further confirmed the nanostructure of NCUs (Fig. 4b). ATP synthase, localized in the thylakoid membrane, served as a membrane marker for the chloroplast. Western blot analysis revealed high expression of the β-subunit of ATP synthase in NCUs, suggesting their potential for ATP production (Fig. 4c).

To investigate the photosynthetic capacity of NCUs, a remote-controlled grow light was made (Supplementary Movie 1). This adjustable grow light fits well with cell culture dish, flask, and well plate, which facilitated our in vitro studies (Supplementary Fig. 7).

Then, the capacity of NCUs to generate ATP and NADPH was measured in a reaction buffer and calculated as “lighting group minus dark control” (Fig. 4d). We found NCUs were able to catalyze the production of ATP from ADP after exposure to light, and the increment increased with light intensity (Fig. 4e) and lighting time (Fig. 4f). As for NADPH production, NCUs catalyzed the light-dependent reduction of NADP⁺ to NADPH, but the manner was different from ATP. Compared to 50 μM and 150 μM photons m⁻²S⁻¹, the optimal light intensity was 100 μM photons m⁻²S⁻¹, which yielded the largest NADPH increment (Fig. 4g). Then, the effect of lighting time was investigated. At the fixed intensity of 100 μM photons m⁻²S⁻¹, lighting for 1 and 2 h produced substantial NADPH increment, whereas the increment reduced and became negative after 4 to 6 h lighting (Fig. 4h). The reduced increment indicated the generated NADPH had been consumed by something else. The formation of ROS is accompanied with photosynthesis¹⁹, we speculated the reductive NADPH was consumed by oxidative ROS. This hypothesis was verified by quadrupling the antioxidant content in the reaction buffer. Compared to normal antioxidant content, fourfold antioxidants significantly decreased NADPH depletion after 6 h lighting (Fig. 4h). These results suggested that the lighting time should be appropriate, not the longer the better.

Next, the stability of NCUs was evaluated. After 4 weeks of storage at − 80 °C, the ATP production capacity decreased by 26.7% (Fig. 4i), while the size distribution didn’t change a lot (Fig. 4j). The biocompatibility of NCUs was confirmed by coculture with H9C2 cells for 3 days (Fig. 4k).

Assessment of the cellular uptake of NCU

The cellular uptake of NCUs was evaluated following a 30 min incubation with H9C2 cells. Fluorescent images revealed successful internalization of NCUs (red) by H9C2 cells (blue) (Fig. 4l), and hypoxia conditions enhanced the uptake behavior (Fig. 4m). Endocytosis is recognized as the primary pathway for nanoparticle cellular internalization²⁰. To clarify the specific mechanism of NCU uptake, we evaluated endocytic pathways using pharmacological inhibitors targeting clathrin-mediated endocytosis (chlorpromazine), caveolae/lipid raft-dependent endocytosis (methyl-β-cyclodextrin), and pinocytosis (amiloride)²¹. Pretreatment with methyl-β-cyclodextrin and amiloride significantly reduced NCU uptake in H9c2 cells (Supplementary Fig. 8), indicating that caveolae/lipid raft-dependent endocytosis and pinocytosis are the primary pathways for NCU cellular entry.

Following endocytic uptake, most nanoparticles are transported to lysosomes for degradation²². To evaluate whether NCUs can escape lysosomal degradation, intracellular lysosomes were stained with LysoTracker. Fluorescent images demonstrated that the majority of internalized NCUs colocalized with lysosomes after 1 h incubation (Supplementary Fig. 9), indicating limited escape capacity of NCUs and impaired sustained intracellular functionality due to potential premature lysosomal degradation.

Effect of NCU on treating cellular H/R injury

To ascertain whether the internalized NCUs can provide ATP and NADPH to H9C2 cells subjected to H/R injury, the remote-controlled light was placed into hypoxia chamber (Fig. 5a). Compared to normal control, 6 h of hypoxia (H6/R0) dramatically decreased ATP content, while the added NCU elevated intracellular ATP levels, and the effect manifested dose-dependent manner (Fig. 5b). Next, the impact of lighting time on intracellular ATP increment was investigated. During 6 h of hypoxia, lighting for 1 h generated the most ATP increment, while lighting for 2 to 6 h resulted in reduced and even negative increments (Fig. 5c), which was similar to previous NADPH production (Fig. 4h).

**Fig. 5: The effect of NCU alone and in combination with GA hydrogel on treating H/R injury.**

After lighting for 1 h during hypoxia stage, H9C2 cells that swallowing NCUs were then subjected to reoxygenation. We found the ATP increment became negative after lighting for 0.5 and 1 h, whereas the no-lighting condition maintained the increment (Fig. 5d). Light microscope images further confirmed the lighting-caused cell injury during reoxygenation (Supplementary Fig. 10c). Therefore, the optimal condition for maximizing ATP increment is 1 h of lighting during hypoxia followed by no lighting during reoxygenation, which will be applied in subsequent experiments.

Since ATP depletion is one of the trigger factors for hypoxia injury, we believed ATP supplementation by NCUs would alleviate cellular injury. As expected, the intervention of NCUs significantly reduced hypoxia injury (Fig. 5e). During reoxygenation, the no-lighting condition exhibited lower injury levels than the H6/R2 group, whereas the lighting exacerbated the cellular injury (Fig. 5f), which was consistent with the ATP increment pattern (Fig. 5d). These results suggested that “NCUs plus Light” only acts in the hypoxia stage.

The capacity of NCUs to enhance intracellular NADPH was also investigated. Compared to normal control, H6/R0 group did not exhibit lower NADPH levels. Conversely, a slight increase in NADPH synthesis was observed in the H6/R0 group (Fig. 5g), which has also been observed in previous in vivo²³ and in vitro²⁴ studies, possibly as a compensatory act to defend hypoxia-induced oxidative stress. The intervention of NCUs significantly increased intracellular NADPH levels (Fig. 5g), which accompanied with lower mitochondria ROS levels than the H6/R0 group (Fig. 5h). The therapeutic effect of NCUs was lastly observed under a light microscope. Compared to H6/R0, the intervention of NCU reduced hypoxia-induced cell death (Fig. 5i and Supplementary Fig. 11).

To determine whether the protective effects of NCU against H/R injury are primarily mediated through ATP generation or NADPH production, we attempted to selectively inhibit ATP synthesis while preserving NADPH production. This was achieved by incubating NCU stock solution with either oligomycin²⁵ (a specific ATP synthase inhibitor) or 2,4-dinitrophenol²⁶ (DNP, an oxidative phosphorylation uncoupler). However, both pharmacological interventions unexpectedly resulted in concurrent suppression of ATP and NADPH production (Supplementary Fig. 12).

Although pharmacological isolation of ATP suppression from NADPH inhibition remains technically challenging, our observation that hypoxia (H6/R0) specifically depletes ATP stores while maintaining NADPH levels (Fig. 5b, g) provides indirect evidence that ATP supplementation plays a major role in reducing H/R injury.

The combination effect of NCU and hydrogel on treating cellular H/R injury

Given that the GA hydrogel can alleviate H/R-induced cell injury, mitochondrial ROS formation, and cell death, in the meantime, the NCU can supplement intracellular ATP deficiency and increase NADPH levels, we hypothesized that their combination (NCU + Gel) could make cells more resilient to extreme conditions and thus achieve a better therapeutic effect. Compared to H6/R0, all three interventional groups (20 μL NCU, 20 μL Gel, and 10 μL NCU + 10 μL Gel) demonstrated less cellular injury (Fig. 5j). Among them, the NCU + Gel group showed better therapeutic effect than an equal volume of NCU, but no significant difference was found between NCU + Gel and Gel groups. As for reoxygenation injury, all interventional groups showed less injury than H6/R2 also (Fig. 5k). Although NCU + Gel and Gel groups exhibited lower injury than an equal volume of NCU, the difference didn’t reach statistical significance. The above results indicated that the combination of NCU and hydrogel exerted a better therapeutic effect than an equal volume of NCU, and this two-component therapeutic system successfully alleviated both hypoxia injury and reoxygenation injury. Lastly, the effect of this combination was further verified in neonatal rat cardiomyocytes (NRCMs) (Fig. 5l), which demonstrated reduced cellular injury in both hypoxia and reoxygenation stages (Fig. 5m, n).

Effect of NCU and GA hydrogel treatment on rat I/R model

Cellular experiments cannot completely reflect the in vivo situation; therefore, we applied these interventional group settings to rat cardiac I/R models. Given the light dependency of our therapeutic system, we firstly performed a light penetration test. The red light successfully penetrated the rat chest wall with an efficiency of 27%, and the maximal penetration intensity was around 309 μM photons m⁻²S⁻¹ (Supplementary Fig. 13), which is much sufficient for enhancing intracellular ATP and NADPH levels based on in vitro experiments.

In this study, rats were randomized into five groups (Fig. 6a): ①DPBS (inject 200 μL DPBS buffer as placebo control), ②DPBS + Light (examine the independent effect of lighting), ③Gel (200 μL GA hydrogel), ④NCU + Light (200 μL NCU, approximately 2 × 10⁹ NCUs), ⑤NCU + Gel + Light (100 μL NCU + 100 μL GA Hydrogel).

**Fig. 6: Effect of NCU and GA hydrogel treatment on rat I/R model.**

One day before surgery, parameters that may affect therapeutic results were measured and compared among five groups, no significant difference was found at baseline (Supplementary Fig. 14). Cellular experiments revealed lighting for 1 h bring the largest ATP increment during hypoxia stage, so as to fully use the ATP production capacity of NCU, the intervention for in vivo ischemic stage is 1 h lighting following intrapericardial delivery (Fig. 6a, b). The intrapericardial injection was conducted immediately after ligating the left anterior descending (LAD) artery to ensure that the therapeutic effects cover both the ischemic and reperfusion stages (Supplementary Movie 2). Accordingly, the ischemic injury was created by ligating LAD for 1 h based on the issued guideline, which suggests 45 to 60 min ligation¹³.

Electrocardiogram (ECG) is a simple and rapid clinical tool for MI diagnosis, reperfusion assessment and outcome evaluation²⁷. To ensure the successful establishment and consistency of all I/R models, ECG was employed (Fig. 6c). Upon the successful ligation of the LAD artery, the ST segment will exhibit a sustained elevation over time. Concurrently, premature ventricular contraction, a result of ischemia, may also be detected. After successful reperfusion, the previously elevated ST segment could gradually fall back (Fig. 6c).

Two hours after the operation, cardiac function was measured using echocardiography (Fig. 6d). The NCU and NCU + Gel groups demonstrated higher left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) than other groups (Fig. 6e, f). Although GA hydrogel exhibited a powerful therapeutic effect on cellular hypoxia injury, it showed no improvement on the impaired cardiac function resulting from LAD ligation. Given that the heart is a high-energy-demanding organ that must continuously consume large amounts of ATP to maintain contractile function²⁸, the NCU effectively ameliorated cardiac function by supplementing the ATP deficiency induced by LAD ligation. However, a functional experiment alone is insufficient to confirm the therapeutic effect. Therefore, the histological experiment, 2,3,5-triphenyltetrazolium chloride (TTC) staining, was conducted (Fig. 6g). Compared to DPBS, NCU plus light indeed reduced ischemic infarction (Fig. 6h).

In addition, the therapeutic efficacy of GA hydrogel and NCU during the acute phase was evaluated by quantifying serum cardiac troponin I (cTnI), a sensitive and specific biomarker for myocardial injury²⁹. At 48 h post-I/R surgery, the Gel group exhibited a significant reduction in cTnI levels compared to the DPBS control (Supplementary Fig. 15), which correlated with upregulated GSS and GPX1 expression at the histological level (Supplementary Fig. 16). Notably, the NCU + Gel group demonstrated the lowest cTnI levels at both 6 h and 48 h timepoints, indicating superior therapeutic efficacy compared to the Gel group and DPBS control (Supplementary Fig. 15).

At day 7, the GA hydrogel demonstrated its therapeutic effect on cardiac function. Compared to DPBS and DPBS + Light groups, the Gel group exhibited an increase in LVEF (Fig. 6i). Furthermore, the NCU + Gel group showed a higher LVEF than the NCU group, although this difference was not statistically significant (Fig. 6i). These findings suggest that the GA hydrogel played its role in mitigating reperfusion injury. At day 14, the LVEF trend did not change significantly compared to day 7 (Fig. 7a).

**Fig. 7: Long-term effect of NCU and GA hydrogel treatment on rat I/R model.**

At the 28-day endpoint, the best cardiac function was found in NCU + Gel group whose LVEF and LVFS finally surpassed NCU group, and the Gel group demonstrated improved cardiac function compared to DPBS groups (Fig. 7b, c and Supplementary Fig. 17). Histological examination using Masson’s trichrome staining revealed extensive infarction in the DPBS and DPBS + Light groups, while the NCU and Gel interventions significantly reduced it (Fig. 7d). Specifically, the NCU + Gel group showed the least infarct size, followed by the NCU and then the Gel group (Fig. 7e). The effect of NCU + Gel was also assessed using TUNEL assay at day 3 (Supplementary Fig. 18a). Compared to DPBS, NCU + Gel significantly reduced myocardial apoptosis (Supplementary Fig. 18b).

Next, ECG parameters were analyzed. Compared to baseline, the DPBS and DPBS + Light groups showed significant waveform changes at day 28, with the normal QRS complex transforming into a fragmented QRS complex (Fig. 7f), indicating the formation of myocardial scar³⁰. However, the QRS complex remained relatively normal and recognizable in the other three interventional groups at day 28 (Fig. 7f). Prolongation of QRS duration is a marker of adverse ventricular remodeling and is associated with an increased risk of heart failure^31,32. Compared to baseline, the NCU + Gel group showed the least increase in QRS duration at day 28 (Fig. 7g), suggesting the least ventricular remodeling and heart failure risk. In addition, an increase in R-wave amplitude indicates improved myocardial perfusion and the presence of salvaged myocardium after MI³³. The NCU + Gel group showed the minimal decrease in R-wave amplitude (Fig. 7h), suggesting a larger area of myocardial perfusion and salvaged myocardium compared to other groups. Finally, the safety profile of this plant-derived therapeutic system, including potential immune rejection (reflected by total white blood cell count with lymphocyte and monocyte percentages)³⁴, allergic reactions (indicated by basophil and eosinophil percentages)³⁵, inflammatory state (C-reactive protein levels)³⁶, and systemic toxicity (hepatic/renal function biomarkers), was verified through complete blood count and blood biochemistry tests on day 28 (Supplementary Fig. 19).

Discussion

Currently, lots of achievements have been made on reperfusion therapy and post-operation management, like the development of interventional devices (stent, balloon, and intracoronary imaging) and medications for outcome improvement (angiotensin receptor-neprilysin inhibitor and proprotein convertase subtilisin/kexin type 9 inhibitor)³⁷. However, treatments for the ischemic stage, the interval between symptom-onset and successful reperfusion, progress slowly. The existing treatments for ischemic stage include oxygen inhalation, sublingual nitroglycerin, pain relief, and basic life support, which mainly provided by emergency medical services³⁸. These supportive treatments cannot substantially alleviate ischemic injury, they are just preparations for the in-hospital reperfusion. As ischemic stage is a major contributor to infarct size³, if this stage can be properly treated, together with the existing therapeutic strategies, the clinical effect could be maximized.

To effectively intervene the ischemic stage, two issues, effective drug and route of administration, need to be addressed. Firstly, regarding the effective drug, since ATP depletion is an initial factor for ischemic injury, therapeutics that supplement ATP deficiency could yield a better effect. In this study, photosynthetic NCUs were used to supply ATP for the ischemic myocardium, leading to improved cardiac function and reduced infarct size. However, another therapeutic component, the GA hydrogel, did not exhibit the same in vivo efficacy against ischemic injury despite its potent therapeutic effects on cellular hypoxia injury. Secondly, determine the drug delivery route. Given the blockage of the coronary artery, drug delivery to the ischemic myocardium via blood circulation may not be efficient. The pericardium, a double-walled sac enveloping the heart, has been identified as a potential route for drug delivery. Preclinical studies have shown that intrapericardial injection can be an effective method for treating MI and heart failure^39,40,41. Furthermore, echocardiography-guided and fluoroscopy-guided intrapericardial procedures are routinely performed in clinical practice for the treatment of cardiac tamponade⁴², pericarditis⁹, and cardiac arrhythmia⁴³. Based on this information, intrapericardial injection was employed in this study. Our results indicated that intrapericardial injection of NCU + Gel resulted in superior short-term and long-term therapeutic effects on cardiac I/R injury.

Reperfusion injury is another contributor to infarct size, and excessive ROS formation is one of the trigger factors for this injury⁴. In this study, we discovered that the GA hydrogel eliminated reoxygenation-induced ROS formation through upregulating GSS and GPX1 at the cellular level. Further in vivo studies revealed GA hydrogel upregulated GSS and GPX1 at the histological level and improved cardiac function at day 7; and by day 28, the cardiac function in the NCU + Gel group had surpassed that of the NCU group alone. These in vivo findings were largely consistent with the outcomes of cellular experiments, which showed that the hydrogel reduced reoxygenation injury in a time-dependent manner (Fig. 2j). Additionally, the GA hydrogel can prevent intrapericardial delivery-associated pericarditis by inhibiting S. aureus (Supplementary Fig. 6).

Compared to the previous study that utilized the plant photosynthetic system in mammalian cells⁵ and the study demonstrating the therapeutic effects of GA in myocardial I/R injury⁶, our study has advantages and disadvantages. In 2022, Chen et al.⁵ pioneered the application of the plant photosynthetic system in mammalian cells by isolating spinach thylakoid membranes to create nano-sized thylakoid units (NTUs). To facilitate cross-species applications and minimize lysosomal degradation, chondrocyte membranes (CM) were used to encapsulate NTUs, resulting in CM-NTUs. Subsequent experiments revealed that CM-NTUs enhanced ATP/NADPH levels in degenerated chondrocytes in vitro and mitigated osteoarthritis progression following intra-articular injection in vivo. In our study, aiming to fully utilize Glycyrrhiza without incorporating additional materials, we did not modify these NCUs. Although these unmodified NCUs performed adequately in our experiments, we observed lysosomal uptake after 1 h of incubation with H9C2 cells (Supplementary Fig. 9), which could lead to premature degradation and compromised long-term functionality. Regarding GA therapeutics, Lai et al.⁶ reported that intraperitoneal administration of GA dissolved in corn oil alleviated myocardial I/R injury, potentially mediated by the modulation of endoplasmic reticulum stress. In contrast, our study demonstrated that GA hydrogel intervention enhanced ROS scavenging by upregulating GSS and GPX1 both in vitro (Fig. 3c, e) and in vivo (Supplementary Fig. 16), thereby mitigating I/R injury. Nevertheless, we acknowledge that additional mechanisms beyond ROS regulation may contribute to the therapeutic effects of GA hydrogel. Elucidating these additional mechanisms will be critical for optimizing hydrogel formulations and expanding clinical applications, and we plan to investigate them thoroughly in future studies.

As for clinical translation, several aspects need to be improved. Firstly, the solvent of NCU. In this study, NCU was dissolved in DPBS buffer without any cryoprotectants, which may account for the 26.7% reduction in ATP-producing capacity after 4 weeks of storage at − 80 °C (Fig. 4i). In addition, prolonged illumination of NCUs resulted in excessive ROS formation (Fig. 4h), leading to additional cell injury (Fig. 5c). We believe these two deficiencies could be addressed by incorporating suitable cryoprotectants and antioxidants into the DPBS solvent. Secondly, the selection of an appropriate light source for NCU irradiation. The human anterior chest wall has an average thickness of approximately 31.2 mm⁴⁴, which is notably greater than that of rats⁴⁵. For clinical application, the external light source must be capable of penetrating the human chest wall. In a previous study, researchers exposed live and cadaver human tissues to 660 nm red light at various sites, including the skull, spinal cord, upper and lower limbs⁴⁶. They found that with increased irradiance, the 660 nm red light could effectively penetrate tissues up to 50 mm in thickness, which exceeds the thickness of the human anterior chest wall. However, since this study did not include the human chest wall, further investigation is required to determine whether this light source can penetrate the chest wall and function effectively in the heart. This necessitates additional research on larger animal models and human cadaver tissues. Alternatively, an intrathoracic light source could be used for cardiac illumination. Since access to the pericardial cavity is essential for the delivery of therapeutics, a flexible OLED catheter could be employed⁴⁷. After the administration of NCU, this OLED catheter could be left within the pericardial cavity for illumination, similar to the clinical practice of leaving a catheter in the pericardial cavity for continuous pericardial drainage⁴⁸. Thirdly, devices for easy intrapericardial injection. The intervention of the ischemic stage has important value for patients who have to suffer prolonged ischemic injury before successful reperfusion. This includes patients living in remote or underdeveloped areas, those encountering traffic delays during transport, and those who have undergone failed myocardial revascularization attempts. In such scenarios, timely intervening ischemic stage through intrapericardial injection could salvage a large amount of myocardium and improve patient outcomes. A blunt-tip, concealed-needle epicardial access device has been developed and demonstrated its good safety and a high success rate in a clinical trial¹². With advancements in technology and growing clinical demand, we anticipate that the intrapericardial injection could be performed in ambulances with the aid of portable ultrasound in the near future, which will greatly facilitate the intervention of ischemic stage in routine clinical practice.

In conclusion, our two-component therapeutic system, when combined with the intrapericardial delivery route, effectively alleviated both ischemic and reperfusion injuries in vivo. This two-stage interventional strategy has proven to be more effective than addressing either stage alone, offering a promising therapeutic direction for the treatment of MI.

Methods

Ethical statement

All animal studies adhered to the ethical regulations of North Carolina State University, as approved by the Institutional Animal Care and Use Committee (IACUC Protocol 22-422).

Fabrication and characterization of glycyrrhizic acid (GA) hydrogel

GA powder (Sigma, PHR1516) was initially dissolved in DPBS buffer (Gibco, 14190) using simple ultrasonic dispersion. The mixture was then heated to 95 °C in a water bath until a clear solution was achieved. Upon cooling to room temperature (RT), a uniform GA hydrogel was formed.

Scanning electron microscopy (SEM) images of the GA hydrogel were obtained after lyophilization using a benchtop SEM (JCM-7000, Jeol)⁴⁹. Rheological tests were conducted on a rheometer (Anton Paar, MCR 92) fitted with a parallel-plate geometry of 25 mm in diameter. The gap between the upper and lower plates was set to 1 mm.

Cell culture and cell viability

H9C2 cells (ATCC, CRL-1446) were cultured in Dulbecco’s Modified Eagle Medium (DMEM) (Gibco, 11330) supplemented with 10% (v/v) Fetal Bovine Serum (FBS) (Corning). Neonatal rat cardiomyocytes (NRCMs) were isolated from the ventricles of 1-day-old Sprague-Dawley rats using a Primary Cardiomyocyte Isolation Kit (Pierce 88281); when needed, they were cryopreserved according to a previous protocol⁵⁰. Briefly, cells were resuspended in ice-cold freezing media (2-4 million cells/ml), aliquoted into cryovials (1 ml/vial), and frozen via controlled-rate cooling to − 80 °C overnight. Cryovials were transferred to liquid nitrogen for long-term storage within 48 h of freezing.

Cell viability was assessed using the Cell Counting Kit-8 (Dojindo, CK04). To evaluate biocompatibility, H9C2 cells were cocultured with either GA hydrogel or nanosized chloroplast units (NCUs) in a 96-well plate for a specified period. Subsequently, 20 μL of the CCK-8 solution was added to each well, and the plate was incubated for 2 h in an incubator. Finally, the absorbance at 450 nm was measured using a microplate reader.

Cellular hypoxia/reoxygenation (H/R) model

The H/R injury model was established using a hypoxia incubator chamber (Stemcell, 27310). Hypoxia for 6 h was applied to induce hypoxic injury in H9C2 cells⁵¹, while 2 h of hypoxia were used for NRCMs⁵². A glucose-free DMEM (Gibco, 11966) served as the hypoxic medium to induce hypoxia injury, whereas a normal DMEM (Gibco, 11330) supplemented with 10% (v/v) FBS was used as the reoxygenation medium to induce reoxygenation injury.

The Live/Dead Cell Imaging Kit (Invitrogen, 2747522) and the LDH Release Assay Kit (Invitrogen, C20301) were utilized to detect cell death and quantify cellular injury resulting from H/R injury. Imaging for the Live/Dead assay was conducted using an ECHO Revolve microscope, and data analysis was performed using ImageJ software.

Measurement of mitochondrial reactive oxygen species (ROS)

Mitochondrial Superoxide Indicator (Invitrogen, M36008) was employed to evaluate intracellular ROS formation in cultured H9C2 cells, following the manufacturer’s instructions. The nuclei of live cells were counterstained with Hoechst 33342 to facilitate visualization. Imaging was conducted using an ECHO Revolve microscope.

Western blot

Samples were lysed in RIPA buffer (Thermo Scientific, 89900), supplemented with 0.1 mM of a protease inhibitor cocktail (Thermo Scientific, 87786). Proteins were extracted and quantified using a BCA assay (Thermo Scientific, 23208). Following this, proteins were denatured and subjected to electrophoresis on Mini-PROTEAN TGX Stain-Free Gels (Bio-Rad). The resolved proteins were then transferred onto a polyvinylidene difluoride (PVDF) membrane.

The PVDF membrane was blocked with 5% nonfat milk (Bio-Rad, 1706404) in Tris-buffered saline containing 0.1% Tween (w/v) at room temperature (RT) for 1 h. After blocking, the membrane was incubated with the primary antibodies overnight at 4 °C on a shaking platform. The membrane was then washed three times with phosphate-buffered saline containing 0.1% Tween 20, followed by incubation with horseradish peroxidase (HRP)-conjugated secondary antibodies for 1 h at RT.

Finally, the Clarity Western ECL Substrate (Bio-Rad, 1705061) was applied for signal detection, and the resulting chemiluminescent signals were captured using the ChemiDoc Imaging System (Bio-Rad).

Antibodies

GPX1 (Proteintech, 29329-1-AP), Glutathione synthetase (Novus, NBP3-03702), SOD2 (Novus, NBP2-20535), Beta actin (Abcam, ab8226), Caspase-3 (Abcam, ab13585), Cleaved caspase-3 (CST, 9664), Beta subunit of ATP synthase (Agrisera, AS05085), Cardiac troponin I (Abcam, ab47003), HRP-conjugated goat anti-rabbit secondary antibody (Abcam, ab6721), HRP-conjugated goat anti-mouse secondary antibody (Abcam, ab6789), Alexa Fluor 488-conjugated goat anti-rabbit secondary antibody (Abcam, ab150077), Alexa Fluor 647-conjugated goat anti-rabbit secondary antibody (Abcam, ab150079), α-sarcomeric actinin (Abcam, ab137346). TUNEL staining kit was purchased from Promega (G3250).

Antibacterial assays of GA hydrogel

Staphylococcus aureus (S. aureus) (ATCC 12600) and Escherichia coli (E. coli) (ATCC 25922) were selected as representative Gram-positive and Gram-negative bacteria, respectively, to assess the antibacterial efficacy of the GA hydrogel. Initially, the bacteria were incubated overnight in Luria Bertani (LB) broth medium at 37 °C with shaking. The bacteria were then diluted in LB medium to achieve a concentration of 10⁶ colony-forming units (CFU) mL⁻¹. Subsequently, the bacterial suspension was mixed with either GA hydrogel or DPBS and seeded into 96-well plates. The plates were incubated at 37 °C for 12 h. During this incubation, the optical density at 600 nm was measured to monitor bacterial growth. After 12 h of incubation, the bacterial suspension was diluted 1000-fold with DPBS. Finally, 100 μL of the diluted bacterial suspension was spread onto LB agar plates and incubated at 37 °C for 24 h.

Fabrication and characterization of NCUs

The seeds of Glycyrrhiza were purchased from Strictly Medicinal Seeds. After a 6-month growth period, the leaves of glycyrrhiza were harvested for chloroplast isolation using an Isolation Kit (Invent Biotechnologies, CP-011). The isolated chloroplasts were suspended in DPBS buffer and protected from light. To determine the size distribution of intact chloroplasts, the chloroplasts were photographed using a light microscope, and their diameters were calculated using ImageJ software.

The chloroplast solution was then extruded through a series of porous membranes (Whatman, 1, 0.8, 0.4, and 0.1 μm) using a gas extruder (Avestin, LF-50). This process resulted in the fragmentation of intact chloroplasts into NCUs. The size distribution of NCUs was detected using Zetaview. The DPBS-dissolved NCUs were stored at −80 °C until further use.

For the acquisition of transmission electron microscopy (TEM) images of NCUs, the NCUs were loaded onto a 200-mesh copper grid and subjected to negative staining with a 1% uranyl acetate UA solution. After two washes with distilled water and air drying, the samples were prepared for TEM imaging using a JEOL 2000FX TEM.

Assays of NCU activity

The photosynthetic capacity of the NCUs to synthesize ATP and NADPH was assessed in a reaction buffer⁵. The reaction buffer composition included 50 mM HEPES-KOH (Boston Bioproducts), 5 µM ferredoxin (Sigma), 3 mM ADP (Sigma), 5 mM K₂HPO₄ (Sigma), 3 mM NADP⁺ (Sigma), 10 mM sodium L-ascorbate (Sigma), 10 mM KCl (Sigma), 5 mM MgCl₂ (Sigma), 3 µM catalase (Sigma), and 100 U mL⁻¹ bovine superoxide dismutase (Sigma).

The reaction was carried out in a 6-well plate, with each well containing 900 μL of the reaction buffer and 500 μL of NCU solution (approximately 4 × 10⁹ NCUs). ATP and NADPH concentrations were measured using the ATP Detection Assay Kit (Abcam, ab113849) and the NADPH Assay Kit (Abcam, ab186031), respectively.

To specifically inhibit ATP production capacity, NCU solution was pre-treated with either oligomycin (2.5 μM; MCE) or 2,4-dinitrophenol (20 μM; Sigma) for 2 h at 4 °C. After incubation, the treated NCUs were introduced into the reaction buffer to assess residual ATP and NADPH synthesis capacities.

Cellular uptake of NCUs

H9C2 cells were utilized for cellular uptake experiments. The cells were incubated in 8-well glass slides (Millicell, PEZGS0816) and cultured for 1 day. Prior to coculture with H9C2 cells, the NCUs were labeled with Dil (Invitrogen, V22885).

To investigate the impact of hypoxia and normal culture conditions on cellular uptake, 200 μL of either hypoxic medium or normal culture medium was added to the wells. Subsequently, 40 μL of the NCU solution (containing 2 × 10⁸ NCUs) was added to the respective wells and incubated for 30 min. The cell samples were then washed with PBS and fixed with 4% paraformaldehyde for 20 min.

Following fixation, the cells were stained with 4’,6-diamidino-2-phenylindole (DAPI) (Invitrogen, 2747527) for 20 min at room temperature to label the nuclei. Finally, the slides were examined using a laser confocal microscope (Olympus, Fluoview FV3000).

NCUs uptake pathway determination

H9c2 cells were seeded in 8-well glass slides and cultured for 24 h. Subsequently, cells were pretreated with endocytosis inhibitors, including chlorpromazine (63 μM), methyl-β-cyclodextrin (5.7 mM), and amiloride (44 μM), which were dissolved in HBSS for 30 min at 37 °C. Following inhibitor removal and washing with DPBS, 200 μL of fresh normal culture medium was added to each well. NCU internalization was initiated by introducing 40 μL of Dil-stained NCU solution (2 × 10⁸ NCUs) into the respective wells, followed by a 30-min incubation at 37 °C. Fluorescence quantification was performed as previously described to assess NCU uptake.

LysoTracker™ Red (Invitrogen, L7528) was used to label intracellular lysosomes following the manufacturer’s protocol.

Rat ischemia/reperfusion (I/R) model and intrapericardial injection

Male Sprague-Dawley (SD) rats, strain code 400 (Charles River), were utilized in this study. Rats are housed with 12 h light/12 h dark cycle at a temperature of 25 °C with 40–60% humidity. I/R models were established by ligating the left anterior descending artery (LAD) for 1 h, followed by continuous reperfusion.

The rats were anesthetized using isoflurane inhalation (2% in oxygen). The LAD was ligated with a 6-0 suture. A gastight syringe (Hamilton, 1725) fitted with a 22 G needle was used for intrapericardial injection (Supplementary Movie 2), with a volume of 250 μL. After surgery, the rats were given continuous 3 injections of buprenex (0.01 mg/kg) and carpofen (5 mg/kg) intraperitoneally for pain management.

Rat electrocardiogram (ECG) recording

Rats were initially anesthetized using 2% isoflurane inhalation. Following anesthesia, needle electrodes were inserted subcutaneously into the limbs of the rats according to the manufacturer’s instructions. ECG waves were recorded using an IX-BIO4 recorder (iWorx). Data acquisition and analysis were conducted using LabScribe software.

Measurement of cardiac function

Transthoracic echocardiography was performed using a Philips CX30 system equipped with a 15 MHz probe⁵³. The rat was anesthetized by inhalation of a 2% isoflurane mixture in oxygen. Initially, B-mode imaging was acquired, followed by long-axis M-mode imaging. Subsequently, the left ventricular ejection fraction (LVEF), left ventricular volume at end-diastole (LV-EDV), and left ventricular volume at end-systole (LV-ESV) were measured. All measurements were obtained from three consecutive cardiac cycles.

2,3,5-triphenyltetrazolium chloride (TTC) staining

TTC powder was purchased from Sigma (T8877). The staining process was conducted in strict accordance with the methodology outlined in the “Measuring Infarct Size By The Tetrazolium Method”, described by James M. Downey (https://www.southalabama.edu/ishr/help/ttc/).

Histological analysis

At the endpoint of the study, rats were anesthetized via intraperitoneal injection of Ketamine-Xylazine. Following intracardiac perfusion with chilled PBS, the hearts were collected and fixed in 10% neutral buffered formalin for 24 h. After washing with PBS for 2 h, the tissues were transferred to 30% (w/v) sucrose and incubated for an additional 24 h before being embedded with OCT compound. A series of cryosections, 5 μm in thickness, were cut and stored at − 20 °C for future use⁵⁴.

Trichrome Masson staining (Sigma, HT10516) and hematoxylin-eosin staining (Abcam, ab245880) were performed according to the manufacturer’s instructions, respectively. For immunostaining, cryosections were washed with PBS and equilibrated with blocking serum at room temperature (RT) for 1 h, followed by incubation with primary antibodies at 4 °C overnight⁵⁵. After three washes with PBS, the corresponding secondary antibodies were added and incubated at RT for 2 h. A DAPI-containing mountant (Invitrogen, P36935) was used for nuclear staining. TUNEL staining was conducted according to the manufacturer’s instructions (Promega, G3250). Imaging was carried out using an Olympus FLUOVIEW FV3000 confocal laser scanning microscope.

Blood test in rats

Blood count and blood biochemistry tests were performed by the Department of Clinical Pathology, College of Veterinary Medicine, NC State University. Serum C-reactive protein (Abcam, ab108827) and cardiac troponin I (Abcam, ab246529) levels were measured using commercial ELISA kits according to the manufacturer’s instructions.

Statistical analysis

Statistical analysis was conducted using GraphPad Prism 9 (Version 9.0.0.121). Data are presented as mean ± standard deviation. Specific statistical tests employed are detailed in the respective figure captions. P < 0.05 was considered statistically significant, P-values are indicated directly on the graphs.

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.

Data availability

All data supporting the conclusions of this study are presented in the article and the Supplementary Information. Source Data are provided in this paper.

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Acknowledgements

The present study was financially supported by grants from the National Natural Science Foundation of China (81271927 to J.W.), the Natural Science Fund of Shanghai (18ZR1431000 to J.W.). K.C. is not supported by the aforementioned funding, but thanks NC State University and Columbia University for support. The funding bodies had no involvement in the design of the study, collection, analysis, or interpretation of data, or manuscript writing.

Author information

These authors contributed equally: YongBo Lv, Dashuai Zhu.

Authors and Affiliations

Department of Cardiology, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China
YongBo Lv & Juan Wang
Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
YongBo Lv, Junlang Li, Chao Lu & Ke Cheng
Department of Biomedical Engineering, Columbia University, New York, NY, USA
Dashuai Zhu, Yuan Li, Ke Huang, Shiqi Hu, Shuo Liu, Na Yan & Ke Cheng
The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
Chao Lu & Jianing Bi
Department of Cardiology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
Juan Wang

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YongBo Lv
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Contributions

Y.B.L., J.W., K.C., and K.H. conceived and designed the study. Y.B.L., D.Z., J.L., Y.L., C.L., and J.B. developed the methodology and implemented the research framework. Investigation involving data acquisition and analysis was conducted by Y.B.L., D.Z., J.L., and Y.L. Visualization tasks such as figure preparation were led by Y.B.L. and D.Z. with contributions from S.L., S.H., and N.Y. J.W. supervised the overall research project.

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Correspondence to Ke Cheng or Juan Wang.

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Lv, Y., Zhu, D., Li, J. et al. Plant-derived hydrogel and photosynthetic nano-units for myocardial infarction therapy. Nat Commun 16, 7678 (2025). https://doi.org/10.1038/s41467-025-62020-5

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Received: 12 December 2024
Accepted: 08 July 2025
Published: 18 August 2025
Version of record: 18 August 2025
DOI: https://doi.org/10.1038/s41467-025-62020-5