TY - JOUR
T1 - Development of a three-dimensional physiological model of the internal anal sphincter bioengineered in vitro from isolated smooth muscle cells
AU - Hecker, Louise
AU - Baar, Keith
AU - Dennis, Robert G.
AU - Bitar, Khalil N.
PY - 2005/8
Y1 - 2005/8
N2 - Fecal incontinence affects people of all ages and social backgrounds and can have devastating psychological and economic consequences. This disorder is largely attributed to decreased mechanical efficiency of the internal anal sphincter (IAS), yet little is known about the pathophysiological mechanisms responsible for the malfunction of sphincteric smooth muscle at the cellular level. The object of this study was to develop a three-dimensional (3-D) physiological model of the IAS bioengineered in vitro from isolated smooth muscle cells. Smooth muscle cells isolated from the IAS of rabbits were seeded in culture on top of a loose fibrin gel, where they migrated and self-assembled in circumferential alignment. As the cells proliferated, the fibrin gel contracted around a 5-mm-diameter SYLGARD mold, resulting in a 3-D cylindrical ring of sphincteric tissue. We found that 1) the bioengineered IAS rings generated a spontaneous basal tone, 2) stimulation with 8-bromo-cAMP (8-Br-cAMP) caused a sustained decrease in the basal tone (relaxation) that was calcium-independent, 3) upon stimulation with ACh, bioengineered IAS rings showed a calcium- and concentration-dependent peak contraction at 30 s that was sustained for 4 min, 4) addition of 8-Br-cAMP induced rapid relaxation of ACh-induced contraction and force generation of IAS rings, and 5) bioengineered sphincter rings show striking functional differences when compared with bioengineered rings made from isolated colonic smooth muscle cells. This is the first report-of a 3-D in vitro model of a gastrointestinal smooth muscle IAS. Bioengineered IAS rings demonstrate physiological functionality and may be used in the elucidation of the mechanisms causing sphincter malfunction.
AB - Fecal incontinence affects people of all ages and social backgrounds and can have devastating psychological and economic consequences. This disorder is largely attributed to decreased mechanical efficiency of the internal anal sphincter (IAS), yet little is known about the pathophysiological mechanisms responsible for the malfunction of sphincteric smooth muscle at the cellular level. The object of this study was to develop a three-dimensional (3-D) physiological model of the IAS bioengineered in vitro from isolated smooth muscle cells. Smooth muscle cells isolated from the IAS of rabbits were seeded in culture on top of a loose fibrin gel, where they migrated and self-assembled in circumferential alignment. As the cells proliferated, the fibrin gel contracted around a 5-mm-diameter SYLGARD mold, resulting in a 3-D cylindrical ring of sphincteric tissue. We found that 1) the bioengineered IAS rings generated a spontaneous basal tone, 2) stimulation with 8-bromo-cAMP (8-Br-cAMP) caused a sustained decrease in the basal tone (relaxation) that was calcium-independent, 3) upon stimulation with ACh, bioengineered IAS rings showed a calcium- and concentration-dependent peak contraction at 30 s that was sustained for 4 min, 4) addition of 8-Br-cAMP induced rapid relaxation of ACh-induced contraction and force generation of IAS rings, and 5) bioengineered sphincter rings show striking functional differences when compared with bioengineered rings made from isolated colonic smooth muscle cells. This is the first report-of a 3-D in vitro model of a gastrointestinal smooth muscle IAS. Bioengineered IAS rings demonstrate physiological functionality and may be used in the elucidation of the mechanisms causing sphincter malfunction.
KW - 8-bromo-adenosine 3′,5′-cyclic monophosphate
KW - Extracellular matrix
UR - http://www.scopus.com/inward/record.url?scp=22544432238&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=22544432238&partnerID=8YFLogxK
U2 - 10.1152/ajpgi.00335.2004
DO - 10.1152/ajpgi.00335.2004
M3 - Article
C2 - 15774939
AN - SCOPUS:22544432238
SN - 0193-1857
VL - 289
SP - G188-G196
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 2 52-2
ER -