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Article History

Received: 5 December 2025

Accepted: 1 June 2026

First Online: 16 June 2026

Declarations

Ethics approval and consent to participate: This study obtained ethics approval and is part of a larger research project that may result in multiple related publications under a single overarching ethics approval. For animal studies, all experimental procedures were performed in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and ARRIVE guidelines 2.0. The animal experiments were approved by the Ethics Committee for Animal Experimentation at Guangdong Provincial People’s Hospital of Guangdong Academy of Medical Sciences (Approval No. 2019482 A; R2: “Preclinical research on stem cell therapy for myocardial infarction”), initially granted in October 2019. The study was subsequently renewed under Approval No. S2025-613-02: “SFMA/HA-E hydrogel combined with human umbilical cord mesenchymal stem cell exosomes can inhibit rat cardiomyocyte apoptosis through macrophage polarisation and angiogenesis.” At experimental endpoints, rats were euthanized by intraperitoneal injection of sodium pentobarbital at 150 mg/kg body weight, followed by cervical dislocation to ensure death. All euthanasia procedures were performed by trained personnel in accordance with institutional guidelines. For human umbilical cord mesenchymal stem cell isolation, Wharton’s jelly was obtained from umbilical cord tissue after healthy full-term deliveries. The project titled “Isolation and characterization of human umbilical cord mesenchymal stem cells for cardiac repair research” was approved by the Ethics Committee of Guangdong Provincial People’s Hospital (Approval No. S2025-613-02; date of approval: March 15, 2025). Written informed consent was obtained from all donors or their legal guardians prior to sample collection, in accordance with the Declaration of Helsinki. Commercial cell lines used in this study were purchased from Cobioer Biosciences Co., Ltd., China: H9C2 rat cardiomyoblasts (Cat. No. CBP60588) and EA.hy926 human endothelial cells (Cat. No. CBP60714). H9C2 is a rat-derived cell line and therefore does not involve human donor consent in this study. EA.hy926 is a human-derived endothelial cell line; the vendor/source documentation confirmed that the original source complied with applicable ethical approval and informed-consent requirements. Supporting vendor documentation and/or material transfer documentation is available from the corresponding author upon reasonable request.

Competing interests: The authors declare no competing interests.