The complexity in the molecular mechanism of the internal anal sphincter (IAS) limits preclinical or clinical outcomes of fecal incontinence (FI) treatment. So far, there are no systematic reviews of IAS translation and experimental studies that have been reported. This systematic review aims to provide a comprehensive understanding of IAS critical role in FI. Previous studies revealed the key pathway for basal tone and relaxation of IAS in different properties as follows; calcium, Rho-associated, coiled-coil containing serine/threonine kinase, aging-associated IAS dysfunction, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase, and inhibitory neurotransmitters. Previous studies have reported improved functional outcomes of cellular treatment for regeneration of dysfunctional IAS, using various stem cells, but did not demonstrate the interrelationship between those results and basal tone or relaxation-related molecular pathway of IAS. Furthermore, these results have lower specificity for IAS-incontinence due to the included external anal sphincter or nerve injury regardless of the cell type. An acellular approach using bioengineered IAS showed a physiologic response of basal tone and relaxation response similar to human IAS. However, in both cellular and acellular approaches, the lack of human IAS data still hampers clinical application. Therefore, the IAS regeneration presents more challenges and warrants more advances.
Fecal incontinence (FI) can be a devasting and stigmatizing disease for elderly patients [
It is also known that resting pressure maintained by the basal tone of IAS is a main clinical parameter of FI [
As an intrinsic force of the sphincter SM, the basal tone is generated from the cross-bridge movement of myosin and actin filaments on 20-kDa myosin regulatory light chain phosphorylation (p-MLC20) [
However, the complexity in the molecular mechanism of myogenic features in IAS might limit preclinical or clinical outcomes of FI cell therapy or regenerative medicine. These treatment modalities should entail the molecular basis of SMCs, which generate basal tone as an intrinsic property and the relaxation in IAS [
To identify all the available translation and experimental studies on the IAS in FI published and indexed up to January 31, 2022, a systematic search was conducted in PubMed, Cochrane Library, EMBASE, Medline, and Web of Science. This strategy included
Automatic deduplication of the retrieved articles was performed twice with EndNote (ver. X9.0.1, Clarivate Analytics, Philadelphia, PA, USA); first per the searched database, and then based on the relevant titles with the assessment of IAS SMCs-related terms including the basal tone, the relaxation, cell therapy, and regeneration medicine. Studies including anatomy and histology were excluded. Two independent reviewers extracted the data from the designed extraction form. Translation studies for SMCs of IAS were classified using keywords as follows: calcium, Rho/ROCK, AAID, oxidative stress, renin-angiotensin-aldosterone, cyclooxygenase (COX), and inhibitory NTM (
Calcium (Ca2+) activation in Ca2+/calmodulin/myosin light chain kinase (MLCK) pathway plays a critical role in the initial phasic stage of IAS tone development via G protein-coupled receptor (GPCR) activation, and in promoting the p-MLC20 [
Serving as the pacemaker, Ca2+-activated Cl− channel TMEM16A also propagates electrical slow waves (SWs) into IAS–SMCs, inducing basal tone via the depolarization and activation of L-type VDCCs and giving rise to CTs in the SMCs. The pharmacological and spatiotemporal properties of CTs in the IAS are very similar to those of SWs with the greatest frequency and amplitude at the distal end of the IAS, suggesting that this is the predominant pacemaker region. Phasic activity by the fastest and highly coordinated pacemaker located at the distal extremity will lead to orally directed contractions that will aid in maintaining continence [
The basal tone in the IAS is critically dependent on RhoA/ROCK [
It has been reported that several factors are involved in the regulation of basal tone in IAS via modulating the molecular pathway of RhoA/ROCK in the previous studies [
Clinically, degenerative transformation of the anal sphincter muscles can be characterized by decreasing IAS tone and increasing response to RAIR and subsequent decreased resting pressure rather than squeezing pressure. Recently, some authors defined AAID with the molecular mechanisms and impeded the development of a specific and safe treatment for AADI-related FI [
Furthermore, the miRNA-133a and its gene targets are crucial to the RhoA signaling pathway in relation to contractility and IAS SM phenotype in aging [
The antioxidant defense mechanisms, such as superoxide dismutase (SOD), catalase, and glutathione peroxidase play a crucial counterregulatory role in ROS levels which are produced during aerobic cellular metabolism. However, with aging, the weakening of the antioxidant defense mechanism can bring about cumulative effects of excessive ROS and results in irreversible cellular damage. As an aging-related risk factor, oxidative stress has been reported to decrease the overall propulsive activity of the gut. A decrease in IAS tone and altered gut motility may be the leading causes of AAID via decreasing phosphorylation of the myosin-binding subunit of MYPT1 and regulatory MLC (MLC20), secondary to RhoA-associated kinase (RhoA/ROCK) inactivation [
Singh et al. [
In the pathway of the RAS, renin converts angiotensinogen into angiotensin I, and angiotensin I is converted into ANG II by the angiotensin-converting enzyme (ACE). ANG II activates specific membrane receptors in the target cells, and binds to 2 different subtypes of GPCRs; AT1-R and AT2-R. Previous studies demonstrated that RAS via ANG II biosynthesis inhibitor (ACE inhibitor) and release of ANG II followed by activation of AT1-R and AT2-R, provide a partial regulation of the basal tone in the IAS [
IAS relaxation presented as RAIR in response to defecation is dependent on nerve activity with NTMs [
The interstitial cells of Cajal (ICC), which are located in close proximity to the nerves throughout most of the GI tract including IAS, participate in nitrergic and cholinergic NTM in the IAS. In other interstitial cells, platelet-derived growth factor α (PDGFRα) is thought to be responsible for the purinergic component of inhibitory NTM. ICC and PDGFRα cells are both closely associated with neural NOS neurons in the IAS. SMCs from gap junctions with adjacent ICC and PDGFRα cells, give rise to an electrical syncytium referred to as the “SIP syncytium”. The nitrergic relaxation in the IAS results from the signals integration by GC within the SIP syncytium, while cGMP-dependent protein kinase I and its downstream targets are responsible for less than half of the relaxation [
Inoue et al. [
In contrast to cellular treatment, scaffolding or gut engineering using natural biomaterial has been employed for IAS malfunctions [
Several translation studies have revealed the molecular mechanism of SMC in IAS as intrinsic properties, which can be characterized by Ca2+, RhoA/ROCK, AAID, oxidative stress, RAS, COX, and inhibitory NTM. However, we observed that previous cellular treatments [
The best option of cell source and phenotype is still a questionable issue in the field of GI regeneration [
Moreover, in the included studies, experimental evidences performed on real human IAS tissue were only 5, and most animal models used rats or mice with contractile protein-specific gene deletion or inhibitory drug. Harvest of viable SMCs of IAS isolated human anal sphincter might be quite difficult because only patients who underwent abdominal perineal resection operation can provide intact anal sphincter. A larger-scale human anal sphincter also needs a new approach for expansion capacity, for example, 3D scaffolding or spheroid culture, and organoids, reflecting that the previous studies have been performed on small size animals like rats or mice. In limitation, we could not performe an interrelationship analysis based on experimental methods for between included molecular mechanisms and regenerative treatment for IAS. Futher study needs with an interrelationship analysis for those.
This study implicates the complexity of the molecular mechanisms for basal tone and relaxation of IAS as intrinsic properties, which change from normal continence into incontinence in FI patients influenced by multifactorial etiology. Many translation studies have revealed the key pathway of IAS for the functional improvement of resting pressure and RAIR in FI. However, experimental evidence of FI cellular treatment has lower specificity for IAS, and a lower interrelationship between the molecular mechanisms of IAS and functional outcomes of cell treatments. Furthermore, there are no reports on lab-grown engineered gut tissues in patients with FI. The field of IAS regeneration presents more challenges and warrants more advances.
No potential conflict of interest relevant to this article was reported.
None.
The interrelationship diagram of molecular mechanisms for basal tone and relaxation of internal anal sphinscter for fecal incontinence. AAID, aging-associated internal anal sphincter dysfunction; ACE, angiotensin-converting enzyme; AR, adrenoceptor; ATP, adenosine 5’-triphosphate; BDNF, brain-derived neurotrophic factor; CO, carbon monoxide; COX, cyclooxygenase; GC, guanylate cyclase; GGTI, geranylgeranyl transferase inhibitor; GPCR, G protein-coupled receptor; HO, heme oxygenase; MLC20, 20-kDa myosin regulatory light-chain; MLCP, myosin light chain phosphatase; MYPT1, myosin phosphatase target subunit 1; NO, nitric oxide; NOS, nitric oxide synthase; NTM, neurotransmitter; PACAP, pituitary adenylate cyclase-activating peptide; PAR1, proteinase-activated receptor-1; PGF2α, prostaglandin F2α; PKC, protein kinase C; RAS, renin-angiotensin system; ROCK, Rho-associated, coiled-coil containing serine/threonine kinase; RyR, ryanodine receptor/channel; TMEM16A, transmembrane member 16A; TXA2, thromboxane A2; VDCC, voltage-dependent Ca2+channel; VIP, vasoactive intestinal polypeptide.
Translation study of molecular pathway for IAS
Study | Year | IAS harvest | Mediator | Pathway | Action of mechanism | |
---|---|---|---|---|---|---|
Calcium (Ca2+) | ||||||
Chakder et al. [ |
1999 | NA | Endothelins 1 and 2 | PKC and the Ca2+-calmodulin pathways | Endothelin-induced contraction of IAS, via inhibition of selective PKC inhibitor H-7 or calmodulin inhibitor W-13 | |
Zhang et al. [ |
2016 | SM-specific MYPT1, TMEM16A, MLCK knockout mice | Global rise in Ca2+ | RyR-TMEM16A-VDCC signaling module | MLCK activation by a global rise in Ca2+ via a RyR-TMEM16A-VDCC signaling module sets a basal tone of IAS | |
Cobine et al. [ |
2020 | SM-GCaMP mice | Spatiotemporal properties of Ca2+ transients | L-type VDCCs | Conduction of CTs rising by slow wave from distal to proximal IAS leading to the maintenance of basal in IAS | |
Lu et al. [ |
2021 | SMC-specific TMEM16A deletion mouse | SCaO | RyR–TMEM16A–VDCCs pathway | IAS basal tone generated by RyR–TMEM16A–VDCCs signaling module mediated by 2 oscillating Ca2+ signals (SCaOs and ACaOs) | |
Rho/ROCK | ||||||
Rattan et al. [ |
2006 | Sprague-Dawley rats | ROCK inhibitor Y-27632 | RhoA/ROCK pathways | Selective ROCK inhibitor (lower doses of Y-27632) relax IAS independent of the NOS/cGMP pathway | |
Patel et al. [ |
2007 | Male Sprague-Dawley rats | RhoA-GTP, ROCK II, MLC20, phospho- MYPT1, phospho- MLC20 | RhoA/ROCK pathways | Upregulation of RhoA/ROCK maintains spontaneous tone in IAS | |
de Godoy et al. [ |
2007 | H- |
H- |
Inhibitory RhoA/Rho kinase machinery | H- |
|
Patel et al. [ |
2007 | NA | GGTI-297 | RhoA prenylation blockade (translocation of RhoA to the SMC membrane) | The inhibitory effect of GGTI-297 maintains a basal tone of IAS via decreasing prenylation of RhoA | |
Rattan [ |
2010 | Sprague-Dawley rats | HMGCRI | RhoA prenylation leading to RhoA/ ROCK translocation | Relaxation of IAS by HMGCRI simvastatin mediated via decreased downstream of RhoA prenylation and ROCK activity | |
Singh et al. [ |
2011 | Human IAS | PDBu | RhoA and ROCK II pathway | PDBu-induced IAS contractility via activation of RhoA/ROCK | |
Rattan et al. [ |
2012 | Human IAS | ROCK- and PKC selective inhibitors Y 27632 and Gö 6850 | RhoA/ROCK pathways | Activation of RhoA/ROCK and downstream signaling determines basal tone in IAS via MLCP inhibition | |
Rattan et al. [ |
2015 | Human IAS tissues | Extracellular signal of TXA2, PGF2α | RAS and arachidonic acid pathways | End products (TXA2, and PGF2α) of both RAS and arachidonic acid pathways causes an increase in the IAS tone via triggering of RhoA/ROCK | |
Rattan et al. [ |
2015 | Male Sprague-Dawley rats | SM22 | Actin-binding properties of SM22 interfering with actin-myosin interaction | Phosphorylation of SM22 in ROCK inhibits SM22-actin interaction leads to basal tone as in IAS | |
Singh et al. [ |
2017 | Rat | miRNA-139-5p | ROCK2 pathway | Overexpression of miRNA-139-5p causes a decrease in the IAS tone | |
AAID | ||||||
Singh et al. [ |
2016 | Fischer rats (F344 of 6-, 18-, and 26-mo-old age) | miRNA133a | RhoA signaling pathway | Aging-associated miRNA133a and its target gene ( |
|
Mohanty et al. [ |
2019 | Fischer 344 rat | Thromboxane A2/ANG II type | GPCR | Downregulation of GPCR via thromboxane A2 and ANG II type 1 receptors desensitization, lysosomal degradation associated with an aging-related decrease in the basal tone of IAS | |
Singh et al. [ |
2020 | Sprague-Dawley rats | BDNF | 1. RhoA/ROCK pathway via TrkB/TXA2-R and AT1-R activation | BDNF-augmented increase in the IAS tone via activation GPCR linked to RhoA/ROCK signaling and NANC Relaxation | |
2. NANC relaxation via NO and soluble GC | ||||||
Singh et al. [ |
2021 | Male Fischer 344 rats (6-mo-old [young group] and 26-mo-old [old group]) | TrkB antagonist | GPCR-coupled agonist-stimulation by activation of RhoA/ROCK and NANC stimulation | BDNF rescues AAID via RhoA/ROCK and decreases the nitrergic NANC inhibitory neurotransmission. | |
Oxidative | ||||||
Krishna et al. [ |
2014 | Sprague-Dawley rats (20–22-wk-old male) | HO-1 | Hemin/HO-1 system | HO (predominantly HO-2 isoform) in neurally mediated relaxation of IAS increases basal tone, and the fibroelastic properties via regulating RhoA/ROCK pathway | |
Singh et al. [ |
2014 | Sprague-Dawley rats; 4–6 mo (adult) and 24–30 mo (aging) | LY83583 | LY83583-mediated a decrease in RhoA/ROCK signal transduction | Oxidative stress is associated with aging-associated decrease in IAS tone via disruption of RhoA/ROCK and downstream signaling cascade | |
Singh et al. [ |
2015 | Adult Sprague-Dawley rats | LY-83583 | nNOS inhibition and RhoA/ROCK pathway | Bimodal effect of oxidative stress (lower vs. higher concentra- tion = 0.1 nM–10 μM vs. 50–100 μM): lower concentrations leads to an increase in IAS tone via nNOS inhibition and RhoA/ROCK activation by LY-83583 | |
RAS and COX | ||||||
De Godoy et al. [ |
2004 | Male Sprague-Dawley rats | ANG II | ACE | Biosynthesis of Ang II-related peptides by ACE activity modulates basal IAS tone via AT1-R activation | |
De Godoy et al. [ |
2005 | Male Sprague-Dawley rats | ANG II precursor angiotensinogen | RAS pathway | RAS regulates basal tone in IAS partially via biosynthesis and releases ANG II by activation of AT1-R | |
De Godoy et al. [ |
2006 | Rat | ANG II | Internalization of subtype I receptor(s) (AT1-R) in the plasma membrane and externalization of subtype II receptor(s) (AT2-R) in the cytosol | Translocation of AT1- and AT2-Rs by higher concentrations of ANG II leads to relaxation of the IAS | |
Inhibitory NTM | ||||||
Moummi et al. [ |
1988 | NA | EFS and exogenous VIP | GC and adenylate cyclase | EFS induces relaxation of SM in IAS mediated via guanosine 5'-cyclic monophosphate | |
Rattan et al. [ |
1992 | NA | NO | NANC inhibitory pathway | Inhibitory NANC by NO-mediated IAS relaxation | |
Rattan et al. [ |
1992 | NA | NO | NANC inhibitory pathway | NO or NO-like substance is an important mediator of IAS relaxation in response to NANC nerve stimulation | |
Chakder et al. [ |
1992 | Mice IAS | NO, VIP, superoxide | Superoxide dismutase | IAS relaxation by NO was suppressed by superoxide and reversed by superoxide dismutase | |
O'Kelly et al. [ |
1993 | Human IAS tissue | NO | NANC inhibitory pathway | NO-mediate neurogenic relaxation of the human IAS | |
Rattan et al. [ |
1995 | Mice IAS | Recombinant hemoglobin | NO pathway | Recombinant hemoglobin suppresses IAS relaxation induced by NO | |
Rattan et al. [ |
1997 | NA | PACAP | N-type Ca++-channel blocker ω-conotoxin | Dual effect: contraction of IAS via the activation of PACAP receptor at P-containing nerve terminals. IAS relaxation by PACAP direct action at nerve terminals of the myenteric inhibitory neurons | |
Chakder et al. [ |
1998 | NA | PACAP | NANC inhibitory pathway | PACAP mediated IAS relaxation via the activation of PACAP1/VIP receptor via presynaptic release of PACAP and VIP by NO | |
Kubota et al. [ |
1998 | Canine | Transmural field stimulation | Membrane hyperpolarization with relaxation | Membrane hyperpolarization relaxes IAS via EFS in the transitional and upper region of IAS | |
Banwait et al. [ |
2003 | Rat | β3-AR | Endothelial NOS | IAS SM relaxation via partly transduced NOS by β3-AR activation | |
Acheson et al. [ |
2003 | Sheep and human IAS | L-arginine, D-arginine | ph and osmolality | L-arginine independent of NO reduce IAS tone | |
Jones et al. [ |
2003 | nNOS knockout mice | NO, antagonists of VIP, ATP, HO | nNOS, nicotinamide adenine dinucleotide phosphate diaphorase HO | NO induces the RAIR primary, and other inhibitory neurotransmitters compensate for the absence of NOS | |
Rattan et al. [ |
2005 | wild-type (WT), HO-2 knockout (HO-2−/−) and nNOS knockout (nNOS−/−) mice | CO, NO, VIP | NANC inhibitory pathway, and nNOS pathway | Inhibitory NANC mediated via activation of nNOS and partly VIP relax IAS. CO is not associated with inhibitory NANC relaxation, which directly relaxes IAS | |
McDonnell et al. [ |
2008 | P2Y1 receptors and apamin-sensitive K+ channels | Purinergic inhibitory neural pathway | Membrane hyperpolarization via purinergic transmission relaxes IAS | ||
Koyuncu et al. [ |
2008 | Rabbit IAS | Isosorbide dinitrate, sodium nitroprusside | NANC inhibitory pathway | NO leads to IAS relaxation via the NANC pathway, but nitrate tolerance was not developed | |
de Godoy et al. [ |
2009 | Knockout mice with selective deletion of COX-1 or COX-2 (COX-1–/– and COX-2–/– mice) | COX-1 | COX-I pathway | Prostanoids produced via COX-1 provide an external trigger for basal tone in IAS | |
de Godoy et al. [ |
2009 | Male Sprague-Dawley rats | Arachidonic acid | COX-I pathway | Arachidonic acid metabolites (PGF2 and thromboxane A2) increases the basal tone of IAS | |
Acheson et al. [ |
2009 | Sheep IAS | NO, noradrenaline | NANC inhibitory pathway | Endogenous noradrenaline acts via postjunctional α1-ARs to antagonize neurogenic relaxations that are largely mediated by NO | |
Duffy et al. [ |
2012 | ATP | Purinergic inhibitory neural pathway | Purinergic hyperpolarization associated relaxation of IAS independent on intramuscular interstitial cells of Cajal | ||
Keef et al. [ |
2013 | VIP−/−mice | VIP | NANC inhibitory pathway | Ultraslow relaxation and hyperpolarization mediated by VIP leading to prolonged IAS relaxation | |
Huang [ |
2014 | Guinea pig IAS | Thrombin and PAR1 peptide agonists | NO pathway | PAR1 and PAR2 mediate relaxation of IAS | |
Cobine et al. [ |
2014 | GC (GCα, GCβ) and NO | NANC inhibitory pathway (GC-dependent, cGKI independent pathway) | Nitrergic effectors in the PDGFRα-cells induce nitrergic relaxation of IAS mediated by GC within the SIP syncytium | ||
Folasire et al. [ |
2016 | Porcine IAS | NO, CO, H2S | NANC inhibitory pathway | Simultaneous release of all 3 gaseous transmitters by EFS induces the relaxations of the IAS |
IASAAID, aging-associated internal anal sphincter dysfunction; ACaO, asynchronized Ca2+ oscillation; ACE, angiotensin-converting enzyme; ANG II, angiotensin II; AR, adrenoceptor; AT1-R, angiotensin II receptor type 1; AT2-R, angiotensin II receptor type 2; BDNF, brain-derived neurotrophic factor; cGKI, cyclic guanosine monophosphate-dependent protein kinase I; cGMP, cyclic guanosine monophosphate; CO, carbon monoxide; COX, cyclooxygenase; CT, Ca2+ transient; EFS, electrical field stimulation; GC, guanylate cyclase; GGTI, geranylgeranyl transferase inhibitor; GPCR, G protein-coupled receptor; GTP, guanosine triphosphate; H2S, hydrogen sulfide; HMGCRI, HMG-CoA reductase inhibition; MLCP, myosin light chain phosphatase; HO, heme oxygenase; IAS, internal anal sphincter; LY-83583, oxidative stress inducer 6-anilino-5,8-quinolinedione; miRNA, microRNA; MLC, myosin light chain; MLCK, myosin light chain kinase; MYPT, myosin phosphatase target subunit; NA, not available; NANC, nonadrenergic noncholinergic; nNOS, neuronal nitric oxide synthase; NO, nitric oxide; NOS, nitric oxide synthase; PACAP, pituitary adenylate cyclase-activating peptide; PAR, proteinase-activated receptor; PDBu, phorbol 12,13-dibutyrate; PDGFR, platelet-derived growth factor receptor; PGF2α, prostaglandin F2α; PKC, protein kinase C; RAIR, rectoanal inhibitory reflex; RAS, renin-angiotensin system; ROCK, Rho-associated protein kinase; RyR, ryanodine receptor; SCaO, synchronized Ca2+ oscillation; SM, smooth muscle; SMC, smooth muscle cell; TMEM16A, transmembrane member 16A; TXA2, thromboxane A2; TXA2-R, thromboxane A2-receptor; TrkB, tyrosine kinase receptor B; VDCC, voltage-dependent Ca2+ channel; VIP, vasoactive intestinal polypeptide.
Treatment of IAS for fecal incontinence; cellular and acelluar approaches
Study | Year | Cell type | Animal (No. of animal) | Type of sphincter injury/confirmation of incontinence | Implantation/factors/scaffolding | Cell tracking | Outcome |
---|---|---|---|---|---|---|---|
Inoue et al. [ |
2018 | ASC sheets | Female Sprague-Dawley rats (n = 18) | Sphincterotomy by the removal of the left semicircle in both the IAS and EAS via a posterior incision/Not confirmed | None | Fluorescence |
Anal manometry, histology |
Salcedo et al. [ |
2013 | Mesenchymal stem cell | Age-matched female Sprague-Dawley rats (n = 70) | Incising the IAS and EAS 2–3 mm deep+pudendal nerve crush/Confirmed via mi- croscopy | IM or IV injection | Green fluorescent protein | Anal manometry, electromyography, immunofluorescence analysis |
Salcedo et al. [ |
2014 | Mesenchymal stem cells | Age-matched female Sprague-Dawley rats (n = 50) | Excision of 25% of the IAS and EAS muscle/Confirmed via microscopy | IM or serial IV injections | Green fluorescent protein | Anal manometry, immunofluorescence, histology |
Kuismanen et al. [ |
2018 | hASC | Sprague-Dawley female virgin rats (n = 60) | Acute fourth grade EAS and IAS muscle and mucosa) and sewed back with 6-0 poliglecaprone/Not con- firmed | Polyacrylamide hydrogel carrier, Bulkamid | Micro-computed tomography | Anal manometry, micro-computed tomography imaging, 3D imaging, histology |
Oh et al. [ |
2015 | Autologous myoblasts | Male mongrel dogs (19–22 kg; 10 wk old) (n = 15) | Resecting 25% of the posterior IAS and EAS by electrocautery/Anal manometry and CMAP confirmed | Polycaprolactone beads | Fluorescent dye PKH-26 | |
Sarveazad et al. [ |
2019 | hASC | Male rabbits (n = 7) | Grade 4 tear at EAS and IAS/ Confirmed via histology, percentage of collagen, muscle | Laser (660 nm, 90 sec, immediately after sphincterotomy, daily, 14 days) | Dil solution | Anal manometry, immunofluorescence, histology, collagen analysis, VEGFA, Ki67 mRNA, vimentin mRNA gene expression profiling |
Hecker et al. [ |
2005 | SMCs from rabbits IAS | None | 3D cylindrical IAS ring/fibrin gel and 5-mm diameter SYLGARD mold | None | ||
Somara et al. [ |
2009 | SMCs from human IAS | None | 3D bioengineered ring model | None | ||
Raghavan et al. [ |
2011 | SMCs from mouse IAS | RAG1−/− mice (NA) | None | Implantation of bioengineered IAS construct in back of mice/IM-FEN cells | None | |
Raghavan et al. [ |
2010 | SMCs from Human and rabbits IAS | C57BL/6J mice | None | Implant subcutaneously on the dorsum of mice/microosmotic pump+fibroblast growth factor-2 | None | |
Raghavan et al. [ |
2014 | SMCs from human IAS | Rat | None | Implant surgically into the perianal region/innervation of enteric neuronal progenitor cells from the human colorectum | None |
ASC, adipose stem cell; CMAP, compound muscle action potential; EAS, external anal sphincter; EFS, electrical field stimulation; hASC, human adipose stem cell; IAS, internal anal sphincter; IM, intramuscular; IM-FEN, immortomouse fetal enteric neuronal; IV, intravenous; mRNA, messenger RNA; NA, not available; PDBu, phorbol 12,13-dibutyrate; PKC, protein kinase C; RAG1, recombination activating gene 1; ROCK, Rho-associated protein kinase; SMC, smooth muscle cell; VEGFA, vascular endothelial growth factor A; VIP, vasoactive intestinal polypeptide; 3D, 3-dimensional.