Injectable extracellular matrix (iECM) is a versatile
biological
material with beneficial properties such as good degradability, promotion
of cell survival, immunomodulation, and facilitation of vascular formation.
However, intravenous injection of iECM faces challenges like a short
retention time in vivo and low concentration at the lesion site. To
address these issues, we prepared a composite hydrogel composed of
sodium alginate and iECM and administered it via intrapericardial
injection, forming a structure akin to cardiac patches within the
pericardium. Compared with intramyocardial injection, intrapericardial
injection avoids direct myocardial injury and ectopic tumor formation,
offering less invasiveness and better biocompatibility. This study
demonstrates that the sodium alginate/infusible extracellular matrix
(SA/iECM) composite hydrogel can effectively prolong the local retention
time of iECM in the heart, enhance electrical conduction between cardiomyocytes,
promote angiogenesis at ischemic myocardial sites, inhibit apoptosis
in the infarcted region, mitigate left ventricular remodeling postmyocardial
infarction (MI), and improve cardiac function after infarction. Precise
coordination of cardiomyocyte contraction and relaxation depends on
the rhythmic occurrence of calcium-dependent action potentials. Cardiac
dysfunction is partially attributed to the disruption of the excitation-contraction
coupling (ECC) mechanism, which is associated with prolonged intracellular
Ca2+ transients and alterations in contraction and relaxation
Ca2+ levels. Our results show that the SA/iECM composite
hydrogel improves electrical conduction, as evidenced by increased
Cx43 expression and enhanced intercellular electrical connectivity.
This research establishes that intrapericardial injection of a SA/iECM
composite hydrogel is a safe and effective treatment modality, providing
a theoretical basis for the use of biomaterials in MI therapy.