Allogeneic biomaterial: a fibrosis inhibitor in ischemic myocardial damage

Abstract

Injectable allogeneic decellularized biomaterials are being developed both as scaffolds for delivery of cellular products and as independent pharmacological agents that affect the cascade of tissue reactions during the period of post-ischemic myocardial remodeling. Biomaterial degradation products can affect cellular processes and modulate cytokine effects, thus determining the healing strategy of damaged tissue. In this work, the influence of biomaterial on the expression of key fibrogenic factors by the cells of tissue bed was demonstrated, and the degree of damage to the myocardium during its ischemic damage was experimentally determined. The aim of our study was to determine the area of myocardial scar degeneration and detection of key fibrogenic factors (bFGF-1, TGFb1, MMP-9), as well as TIMP-2 (MMP-9 antagonist) at the acute and subacute stages of myocardial infarction after implantation of allogeneic powder-like biomaterial in an experimental model.In the course of experiments, the left ventricular coronary artery was ligated in male Wistar rats (experimental group). All animals were divided into 3 groups: experimental group I (n = 50), experimental group II (n = 50), and controls (n = 50). In experimental group I, the artery ligation was simultaneously accompanied by intramyocardial administration of powder-like biomaterial suspension (2 mg). In experimental group II, the allogeneic powder-like biomaterial was administered 5 days after coronary occlusion, and only physiological saline was administered in the control group. The animals were withdrawn from experiment on days +3, +7, +14, +30, and +45. Standard histological assessment (hematoxylin and eosin staining, according to Mallory) and immunohistochemical examination (MMP-9, TGFb1, bFGF-1, TIMP-2) were made, and statistical evaluation was performed. The cells with positive staining were counted, and the scar area index was calculated.We have found that administration of dispersed allogeneic biomaterial was followed by a five-fold decrease in the degree of scar degeneration in both experimental groups at the acute and subacute stages of ischemic myocardial damage as compared to the control group. A significantly decreased expression of fibrogenic factors (MMP-9, TGFb1, bFGF-1) by the local cells was found, along with increased activity of metalloproteinase inhibitor (TIMP-2) in connective tissue cells.Decellularized allogeneic powder-like biomaterial serves as a fibrosis inhibitor and promotes cardioprotection during myocardial remodeling at the initial stages after ischemic injury.