Short communication: vascular smooth muscle cell stiffness as a mechanism for increased aortic stiffness with aging.
BACKGROUND
Increased aortic stiffness, an important feature of many vascular diseases, eg, aging, hypertension, atherosclerosis, and aortic aneurysms, is assumed because of changes in extracellular matrix (ECM).


OBJECTIVE
We tested the hypothesis that the mechanisms also involve intrinsic stiffening of vascular smooth muscle cells (VSMCs).


RESULTS
Stiffness was measured in vitro both by atomic force microscopy (AFM) and in a reconstituted tissue model, using VSMCs from aorta of young versus old male monkeys (Macaca fascicularis) (n=7/group), where aortic stiffness increases by 200% in vivo. The apparent elastic modulus was increased (P<0.05) in old (41.7+/-0.5 kPa) versus young (12.8+/-0.3 kPa) VSMCs but not after disassembly of the actin cytoskeleton with cytochalasin D. Stiffness of the VSMCs in the reconstituted tissue model was also higher (P<0.05) in old (23.3+/-3.0 kPa) than in young (13.7+/-2.4 kPa).


CONCLUSIONS
These data support the novel concept, not appreciated previously, that increased vascular stiffness with aging is attributable not only to changes in ECM but also to intrinsic changes in VSMCs.
Qiu
Hongyu
H
Department of Cell Biology, UMDNJ-New Jersey Medical School, 185 South Orange Ave., Newark, NJ 07103, USA.
Zhu
Yi
Y
Sun
Zhe
Z
Trzeciakowski
Jerome P
JP
Gansner
Meredith
M
Depre
Christophe
C
Resuello
Ranillo R G
RR
Natividad
Filipinas F
FF
Hunter
William C
WC
Genin
Guy M
GM
Elson
Elliot L
EL
Vatner
Dorothy E
DE
Meininger
Gerald A
GA
Vatner
Stephen F
SF
D000199:Actins / Q000378:metabolism; D000367:Age Factors; D000375:Aging / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology; D001018:Aortic Diseases / Q000209:etiology / Q000473:pathology*; D002478:Cells, Cultured; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D055119:Elastic Modulus; D019012:Integrin beta1 / Q000378:metabolism; D008252:Macaca fascicularis; D008297:Male; D018625:Microscopy, Atomic Force; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D014404:Tubulin / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D019012:Integrin beta1; D014404:Tubulin; D014746:Vimentin; D015638:Cytochalasin D