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(Circulation. 1999;100:II-262.)
© 1999 American Heart Association, Inc.

Thoracic Transplantation and Ventricular Assist Devices

Formation of Cell Junctions Between Grafted and Host Cardiomyocytes at the Border Zone of Rat Myocardial Infarction

Tsutomu Matsushita, MD; Masahito Oyamada, MD; Hiroyuki Kurata, MD; Shinsuke Masuda, MD; Akiyuki Takahashi, MD; Takeshi Emmoto, MD; Isao Shiraishi, MD; Yukio Wada, MD; Takahiro Oka, MD; Tetsuro Takamatsu, MD

From the Department of Pathology and Cell Regulation (T.M., M.O., H.K., S.M., I.S., T.T.) and the Second Department of Surgery (T.M., S.M., A.T., T.E., Y.W., T.O.), Kyoto Prefectural University of Medicine, Kyoto, Japan

Correspondence to Tetsuro Takamatsu, Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamikyo-ku, Kyoto, 602-0841 Japan. E-mail ttakam{at}basic.kpu-m.ac.jp

Background—Cardiomyocyte transplantation is an innovative strategy for the treatment of heart failure after myocardial infarction. Cell junctions show diverse temporal polarization toward intercalated disks during postnatal development and exhibit altered distribution in diseased hearts. To elucidate the formation of cell junctions between grafted and host cardiomyocytes at the border zone of myocardial infarction, the 3D distribution of cell junctions was examined using immunohistochemistry and confocal microscopy.

Methods and Results—Neonatal cardiomyocytes obtained from 3-day-old rats by collagenase digestion and Percoll density centrifugation were injected into the border zones of infarction sites 10 days after coronary ligation in adult rats. At 4 to 14 days after transplantation, hearts were harvested and processed by immunohistochemistry. Antibodies against connexin43, desmoplakin, and cadherin were used to analyze the distribution of gap junctions, desmosomes, and adherens junctions, respectively. Grafted cardiomyocytes were identified by immunohistochemistry for -smooth muscle actin. Grafted cardiomyocytes tended to align parallel to the host cardiomyocytes. Connexin43, desmoplakin, and cadherin were localized between grafted cardiomyocytes themselves and between grafted and host cardiomyocytes. Semiquantitative analysis revealed that all junctions showed increasing polarization to longitudinal cell termini, especially at the border of grafted and host cardiomyocytes, as time advanced from 4 to 7 days after transplantation.

Conclusions—These findings indicate that grafted cardiomyocytes foster electrical pathways with host counterparts through the gap junction and suggest that the environment in infarcted hearts could influence the localization of gap junctions, desmosomes, and adherens junctions.

Key Words: gap junctions • transplantation • intercellular junctions • intercalated disk • myocardial infarction