Rui Gao,1,* Demeng Xia,2,* Xiaoyong Zhang,3,* Yao Xiao,3 Hong Zhou,3 Gan Chen,3 Haibin Wang1 

1College of Life Science and Bioengineering, College of Physical Science and Engineering, Beijing Jiaotong University, Beijing, 100044, People’s Republic of China; 2Department of Orthopaedics, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200000, People’s Republic of China; 3Institute of Health Service and Transfusion Medicine, Academy of Military Medical Sciences, Beijing, 100850, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Gan Chen, Email chenlzu2005@163.com; Haibin Wang, Email wanghb@bjtu.edu.cn

Background: Acute myocardial infarction (AMI) is a leading cause of mortality worldwide. Adipose-derived stem cell (ADSC) transplantation presents a promising therapeutic approach for AMI; however, the harsh microenvironment of the infarcted myocardium, characterized by hypoxia and oxidative stress, limits the survival and efficacy of ADSCs. Nanozymes (NZs), which have robust anti-oxidative enzyme-mimicking activities, have demonstrated potential in combating oxidative stress and improving cell viability.
Methods: Mn3O4 NZs (Mn-Nzs), which have nanoflower-like structures were synthesized and their structure and multi-enzyme mimetic activities (superoxide dismutase, catalase, and glutathione peroxidase) were characterized. Blood biochemical parameters were measured in the heart, liver, spleen, lungs and kidneys of the rats, followed by hematoxylin and eosin (HE) staining. The impact of Mn3O4 NZs on reactive oxygen species (ROS) levels, and viability of ADSCs under oxidative stress was assessed in vitro. In vivo studies were conducted using a rat AMI model to evaluate the therapeutic efficacy of ADSC transplantation, in conjunction with Mn3O4 treatment. In addition, proteomic analysis was performed to elucidate the mechanisms of action underlying the therapeutic effects.
Results: Mn3O4 NZs exhibited multi-enzyme mimetic activities, including superoxide dismutase, catalase, and glutathione peroxidase, reducing reactive oxygen species levels and apoptosis in ADSCs under oxidative stress. In the AMI rat model, Mn-NZs had good biocompatibility and ADSC transplantation or Mn3O4 NZs treatment alone significantly reduced infarct size, fibrosis levels, and improved microvascular density and heart function. Notably, the combination of Mn3O4 NZs with ADSC transplantation enhanced ADSC survival and differentiation, amplifying therapeutic efficacy. Proteomic analysis revealed that Mn3O4 4 NZs upregulated proteins associated with anti-oxidative damage, anti-inflammation, and anti-fibrosis pathways. In addition, Mn-NZs upregulated MMP8 via AKT pathway phosphorylation.
Conclusion: The findings highlight a novel strategy integrating NZ anti-oxidant properties with stem cell transplantation to improve AMI treatment outcomes.

Keywords: acute myocardial infarction, adipose-derived stem cell, nanozymes, Mn3O4