The human adult cardiomyocyte phenotype.
OBJECTIVE
Determination of the phenotype of adult human atrial and ventricular myocytes based on gene expression and morphology.


METHODS
Atrial and ventricular cardiomyocytes were obtained from patients undergoing cardiac surgery using a modified isolation procedure. Myocytes were isolated and cultured with or without serum. The relative cell attachment promoting efficiency of several reagents was evaluated and compared. Morphological changes during long-term culture were assessed with phase contrast microscopy, morphometric analysis and immunocytochemistry or RT-PCR of sarcomeric markers including alpha-actinin, myosin light chain-2 (MLC-2) and the adhesion molecule, cadherin.


RESULTS
The isolation method produced viable rod-shaped atrial (16.6+/-6.0%, mean+/-S.E.; n=5) and ventricular cells (22.4+/-8.0%, mean+/-S.E.; n=5) in addition to significant numbers of apoptotic and necrotic cells. Cell dedifferentiation was characterized by the loss of sarcomeric structure, condensation and extrusion of sarcomeric proteins. Cells cultured with low serum recovered and assumed a flattened, spread form with two distinct morphologies apparent. Type I cells were large, had extensive sarcolemmal spreading, with stress fibers and nascent myofibrils, whilst type II cells appeared smaller, with more mature myofibril organisation and focal adhesions.


CONCLUSIONS
Characterization of the redifferentiation capabilities of cultured adult cardiac myocytes in culture, provides an important system for comparing cardiomyocytes differentiating from human stem cells and provides the basis for an in vitro transplantation model to study interaction and communication between primary adult and stem cell-derived cardiomyocytes.
Bird
S D
SD
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht, The Netherlands.
Doevendans
P A
PA
van Rooijen
M A
MA
Brutel de la Riviere
A
A
Hassink
R J
RJ
Passier
R
R
Mummery
C L
CL
D000185:Actinin / Q000032:analysis; D000199:Actins / Q000235:genetics; D000328:Adult; D017209:Apoptosis; D009320:Atrial Natriuretic Factor / Q000235:genetics; D015820:Cadherins / Q000032:analysis; D000252:Calcium-Transporting ATPases / Q000235:genetics; D024722:Cardiac Myosins / Q000235:genetics; D002448:Cell Adhesion / Q000502:physiology; D002469:Cell Separation / Q000379:methods; D002478:Cells, Cultured; D015870:Gene Expression; D006325:Heart Atria; D006352:Heart Ventricles; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008858:Microscopy, Phase-Contrast; D009200:Myocardial Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000502:physiology*; D009210:Myofibrils / Q000502:physiology* / Q000648:ultrastructure; D018994:Myosin Light Chains / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012518:Sarcomeres / Q000648:ultrastructure; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D014335:Tropomyosin / Q000235:genetics
D000199:Actins; D015820:Cadherins; D018994:Myosin Light Chains; D012333:RNA, Messenger; D014335:Tropomyosin; C107184:myosin light chain 2; D000185:Actinin; D009320:Atrial Natriuretic Factor; D024722:Cardiac Myosins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases