A modified apical resection model with high accuracy and reproducibility in neonatal mouse and rat hearts

Abstract

Neonatal mouse heart can regenerate after left ventricle (LV) apical resection (AR). Since current AR rodent method is accomplished by resecting LV apex until exposure of LV chamber, it is relatively difficult to operate reproducibly. We aimed to develop a modified AR method with high accuracy and reproducibility and to investigate whether cardiac regenerative capacity could be replicated in neonatal rats. For 15% AR of whole heart weight in 1-day-old (P1) neonatal mice, a modified 10 μL pipette tip cut to 0.48 mm in internal diameter was connected to a vacuum pump working at 0.06 ± 0.005 MPa and gently kept in touch with LV apex for nearly but no more than 12 s. LV apex was resected by a single incision adjacent to the pipette tip. The modified AR method in P1 mice achieved cardiac structural and functional recovery at 21 days post resection (dpr). Data from different operators showed smaller variation of resected LV apex and higher reproducibility using the modified AR method. Furthermore, we showed that 5% AR of whole heart weight in P1 neonatal rats using a modified 200 μL pipette tip cut to 0.63 mm in internal diameter led to complete regeneration of LV apex and full preservation of cardiac function at 42 dpr. In conclusion, the modified AR rodent model leads to accurate resection of LV apex with high homogeneity and reproducibility and it is practically convenient for the study of structural, functional, and molecular mechanisms of cardiac regeneration in both neonatal mice and rats.

Exercise-Induced miR-210 Promotes Cardiomyocyte Proliferation and Survival and Mediates Exercise-Induced Cardiac Protection against Ischemia/Reperfusion Injury

“…However, the proliferation capacity of cardiomyocytes is very limited in the adult mammalian heart, constraining the heart’s self-renewal ability after injury [ 40 ]. Scientists have used apical resection model to study the cellular and molecular mechanisms of cardiomyocyte proliferation [ 40 , 41 ]. Molecules that are required for cardiac regeneration after apical resection in neonates were found to be able to promote cardiomyocyte proliferation and myocardial repair even in the adult heart [ 42 , 43 ].…”

“…Cardiac cryosections (5 μm thick) or cultured cardiomyocytes were examined with immunofluorescent stainings for α-actinin (diluted with 1:200, Sigma, A7811) and Ki67 (diluted with 1:100, Abcam, ab16667) or stained with α-actinin (diluted with 1:200, Sigma, A7811) and Cell-Light EdU Apollo488 In Vitro Kit (KeyGEN, KGA331) for EdU labeling as previously reported [ 41 ]. The ratio of Ki67-positive or EdU-positive cardiomyocytes was observed under confocal microscopy (Carl Zeiss, LSM710) or fluorescence microscopy (Leica, DMi8) and analyzed using ImageJ software.…”

Comparative Analysis of Heart Regeneration: Searching for the Key to Heal the Heart—Part I: Experimental Injury Models to Study Cardiac Regeneration

“…Like cryoinjury, apical resection does not fully capture the ischemic damage of a MI. Another injury model is apical resection; it consists of the removal of a small piece of tissue, no more than 15%, from the apical left ventricle wall after heart exposure [51,52] (Figure 1A). Immediately after apical resection there is an inflammatory process which ends with the generation of a blood clot that seals the resected area, thus starting the regenerative process [46].…”