Objective:

2

To investigate the involvement of endothelial cells (ECs)-derived exosomes in the anti-apoptotic effect of Danhong Injection (DHI) and the mechanism of DHI-induced exosomal protection against post-infarction myocardial apoptosis.

Methods:

2

A mouse permanent myocardial infarction (MI) model was established

followed by a 14-day daily treatment with DHI

DHI plus GW4869 (an exosomal inhibitor)

or saline. Phosphate-buffered saline (PBS)-induced ECs-derived exosomes were isolated

analyzed by miRNA microarray and validated by droplet digital polymerase chain reaction (ddPCR). The exosomes induced by DHI (DHI-exo)

PBS (PBS-exo)

or DHI+GW4869 (GW-exo) were isolated and injected into the peri-infarct zone following MI. The protective effects of DHI and DHI-exo on MI hearts were measured by echocardiography

Masson's trichrome staining

and TUNEL apoptosis assay. The Western blotting and quantitative reverse transcription PCR (qRT-PCR) were used to evaluate the expression levels of miR-125b/p53-mediated pathway components

including miR-125b

p53

Bak

Bax

and caspase-3 activities.

Results:

2

DHI significantly improved cardiac function and reduced infarct size in MI mice (

P

<

0.01)

which was abolished by the GW4869 intervention. DHI promoted the exosomal secretion in ECs (

P

<

0.01). According to the results of exosomal miRNA microarray assay

30 differentially expressed miRNAs in the DHI-exo were identified (28 up-regulated miRNAs and 2 down-regulated miRNAs). Among them

DHI significantly elevated miR-125b level in DHI-exo and DHI-treated ECs

a recognized apoptotic inhibitor impeding p53 signaling (

P

<

0.05). Remarkably

treatment with DHI and DHI-exo attenuated apoptosis

elevated miR-125b expression level

inhibited capsase-3 activity

and down-regulated the expression levels of proapoptotic effectors (p53

Bak

and Bax) in post-MI hearts

whereas these effects were blocked by GW4869 (

P

<

0.05 or

P

<

0.01).

Conclusion:

2

DHI and DHI-induced exosomes inhibited apoptosis

promoted the miR-125b expression level

and regulated the p53 apoptotic pathway in post-infarction myocardium.