After left
ventricular-assist device (LVAD) support, a proportion of patients recover sufficient ventricular function to enable explantation of the device. The exact molecular mechanisms involved in myocardial recovery remain unknown.
Cytoskeletal proteins are essential for the structure and function of the cardiac myocyte and might play a major role.
METHODS AND RESULTS: A total of 15 patients with nonischemic
cardiomyopathy who required LVAD implantation were studied; 6 recovered sufficiently to allow explantation of the device compared with 9 who did not recover and required
transplantation. LV myocardial samples were collected at implantation and explantation/
transplantation. Affymetrix microarray analysis was performed on the paired samples and analyzed with reference to sarcomeric and nonsarcomeric
cytoskeletal proteins. In the recovery group, of the nonsarcomeric
proteins,
lamin A/C increased 1.5-fold (P<0.05) and
spectrin 1.6-fold (P<0.05) between the times of implantation and explantation.
Integrins beta1, beta6, and alpha7 decreased 1.7-fold (P<0.05), 2.4-fold (P<0.05), and 1.5-fold (P<0.05), respectively, but
integrins alpha5 and beta5 increased 2.3-fold (P<0.01) and 1.2-fold (P<0.01) at explantation. The following sarcomeric
proteins changed in the recovered group only:
beta-actin increased 1.4-fold (P<0.05);
alpha-tropomyosin, 1.3-fold (P<0.05); alpha1-actinin, 1.8-fold (P<0.01); and
alpha-filamin A, 1.6-fold (P<0.05). Both
troponin T3 and alpha2-actinin decreased by 1.6-fold at the time of explantation (P<0.05).
Vinculin decreased 1.7-fold (P=0.001) in the recovered group but increased by 1.7-fold (P<0.05) in the nonrecovered group.
Vinculin protein levels decreased 4.1-fold in the recovered group.
CONCLUSIONS: Myocardial recovery was associated with a specific pattern of changes in sarcomeric, nonsarcomeric, and
membrane-associated proteins, which could have important implications in understanding the mechanisms involved.