Innovative Research Report on Intravenous Macrophage Membrane-Camouflaged Nanozymes for Acute Kidney Injury Targeted Therapy

Background Introduction

Acute kidney injury (AKI) is a severe clinical syndrome characterized by a rapid decline in renal function and is closely associated with high morbidity and mortality. Statistics show that the incidence of AKI is 10%-15% in hospitalized patients and exceeds 50% in intensive care units (ICUs), accounting for over 2 million deaths worldwide annually. In addition to directly threatening life, AKI increases susceptibility to chronic kidney disease (CKD) and end-stage renal disease (ESRD). However, current treatments for AKI remain ineffective in repairing damaged kidney tissues. Therefore, developing innovative therapeutic approaches to better address the underlying mechanisms of AKI is a critical focus in medical research.

Ischemia-reperfusion injury (IRI) is one of the leading causes of AKI, commonly observed in kidney transplantation, renal vascular obstruction, and reduced cardiac output. During IRI, oxygen deprivation and subsequent reoxygenation generate a large amount of reactive oxygen species (ROS), triggering oxidative damage, inflammatory responses, and microvascular rarefaction in renal tissues. These processes exacerbate kidney injury and form an “oxidative stress-microvascular perfusion” negative feedback loop. This mechanism has driven researchers to propose antioxidant therapy as a potential breakthrough for alleviating oxidative stress and improving blood perfusion in AKI treatment.

Addressing this scientific challenge, a research team from Zhejiang University School of Medicine and other institutions published a study titled “Macrophage Membrane-Camouflaged Nanozymes for Combating the Oxidative Stress-Microvascular Perfusion Negative Feedback in Ischemia-Reperfusion Induced Acute Kidney Injury”. Published in the journal Advanced Healthcare Materials, the study explores a novel targeted therapeutic strategy based on macrophage membrane-camouflaged manganese-based antioxidant nanozymes (MB@LM) and demonstrates its highly effective therapeutic potential in an IRI-induced AKI model.

Research Design and Workflow

Overview of Experimental Design and Research Workflow

The research team developed an innovative antioxidant nanozyme (MB@LM) designed to achieve targeted delivery to kidney injury sites, mitigate oxidative stress and inflammatory responses, and restore renal microcirculation perfusion. The experimental workflow consists of the following key steps:

1. Extraction of macrophage membranes and nanozyme synthesis: Using bovine serum albumin (BSA) and potassium permanganate (KMnO4), manganese-based nanozymes (MB) were synthesized via a chemical reduction method. The membranes of RAW264.7 cells activated with lipopolysaccharides (LPS) were then extracted and used to camouflage MB, forming MB@LM.

2. Investigation of AKI-related adhesion molecule expression: Immunofluorescence staining, Western blotting, and other techniques were employed to confirm the high expression of ICAM-1 and VCAM-1 in kidney injury tissues, as well as the potential of camouflaged nanozymes to target injured tissues through adhesion molecules.

3. Evaluation of antioxidant properties: Standardized methods such as DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assays were used to characterize the enzyme-mimicking antioxidant properties of MB@LM.

4. In vitro cell studies: The protective effects of MB@LM on human proximal tubular epithelial cells (HK-2 cells) under H2O2-induced oxidative stress were assessed by evaluating ROS levels, mitochondrial function, and apoptotic rates.

5. Animal model verification and therapeutic efficacy: In a mouse model of IRI-induced AKI, the targeting and therapeutic efficacy of MB@LM were evaluated using B-mode ultrasound and contrast-enhanced ultrasound (CEUS). Serum biochemical analyses (BUN, CRE), gene expression assays, and histopathological analyses were conducted to assess treatment outcomes.

6. Evaluation of biocompatibility: The toxicity and safety of MB@LM in normal mice were extensively evaluated through various measures.

Experimental Workflow Details

1. Nanozyme Design and Characterization

MB was synthesized via reduction of KMnO4 to MnO2 using the reducing functional groups provided by BSA, resulting in spherical manganese nanoparticles approximately 10 nm in diameter. LPS-activated RAW264.7 macrophage membranes, which maintained high expression of integrins LFA-1 (Lymphocyte Function-Associated Antigen-1) and VLA-4 (Very Late Antigen-4), were extracted and used to camouflage MB, forming MB@LM. Transmission electron microscopy (TEM) images revealed that MB@LM had a diameter of approximately 100 nm. Protein retention was validated via SDS-PAGE, and successful membrane coating was confirmed by dynamic light scattering (DLS) and Zeta potential analyses.

2. Antioxidant Capability Tests

Through DPPH and ABTS assays, MB@LM exhibited high efficiency in scavenging free radicals, demonstrating strong ROS-clearing capabilities. Furthermore, MB@LM showed hydrogen peroxide decomposition activity, confirming its enzyme-mimicking characteristics (SOD- and CAT-like activities).

3. Cellular Protection Studies

In an H2O2-induced HK-2 cell oxidative damage model, MB@LM significantly improved cell viability, decreased ROS levels, restored mitochondrial membrane potential, and reduced apoptosis. Live/Dead staining and flow cytometry further confirmed its protective effects.

4. Animal Experiments and Therapeutic Assessments

In an AKI mouse model, MB@LM effectively targeted IRI-induced kidney injury sites via adhesion molecule interaction. Following treatment, serum BUN and CRE levels decreased, renal pathology improved, and renal microcirculation was significantly restored (as validated by CEUS). This therapeutic effect was further corroborated by restored antioxidant and anti-inflammatory gene expression levels.

5. Biocompatibility Validation

MB@LM exhibited low toxicity in normal mouse models, as demonstrated by serum biochemical markers, HE staining, and body weight monitoring. These results highlight its excellent biocompatibility.

Key Findings and Conclusions

This study demonstrated the targeting capability, antioxidant effects, and anti-inflammatory properties of MB@LM, elucidating its mechanism of action in mitigating IRI-induced AKI. MB@LM selectively accumulated in kidney injury sites through interactions with ICAM-1 and VCAM-1, inhibiting oxidative stress and inflammation, and significantly improving renal recovery in AKI mouse models.

Highlights and Significance of the Study

• High Targeting Efficiency: By leveraging macrophage membrane camouflage, the nanozymes effectively evaded clearance by the reticuloendothelial system and selectively accumulated at kidney injury sites.
• Innovative Antioxidant Strategy: The incorporation of manganese-based enzyme-mimicking materials provided exceptional ROS scavenging capabilities, addressing the limitations of naturally derived antioxidants.
• Integrated Multifunctional Therapy: Combined anti-inflammatory, anti-apoptotic, and antioxidant properties enabled a groundbreaking approach to AKI treatment.
• Excellent Biocompatibility: The nanozymes demonstrated promising safety and feasibility for clinical applications.

Conclusion

By targeting oxidative stress and microvascular perfusion deficiencies in AKI, MB@LM represents an innovative treatment strategy. This study provides new perspectives for treating AKI and other oxidative stress-related diseases. Additionally, it underscores the wide-ranging potential of biomimetic nanomedicine, laying a solid foundation for further optimization and clinical translation in the future.