Stromal Cell-Derived Factor 1 Plasmid Regenerates Both Smooth and Skeletal Muscle After Anal Sphincter Injury in the Long Term

The Effect of Dosing of Stromal Cell-Derived Factor 1 on Anal Sphincter Regeneration

Aim: The aim of this study is to investigate if a high dose of the stromal cell-derived factor-1 (SDF-1) plasmid improves outcome in a minipig model of chronic anal sphincter injury. Methods: Twenty-two female minipigs underwent excision of the posterior hemicircumference of the anal sphincter complex and were allowed to recover for 6 weeks. They were randomly allocated (n = 6) to receive either 5% dextrose (sham) or 2, 4, or 8 mg of SDF-1 plasmid at the defect site. Two control pigs received no surgery/treatment. Outcome measures included anal manometry at preinjury/pretreatment and 2, 4, and 8 weeks after treatment, recording the mean of eight pressure channels and the posterior channel alone, histopathology using Masson's trichrome, and immunohistochemistry using PGP9.5 for staining of neural structures, and CY3 staining for blood vessels. Data are expressed as mean ± standard error. Manometry analysis used two-way analysis of variance (ANOVA) followed by the Holm-Sidak test. Quantification of muscle/fibrosis was analyzed with a Kruskal-Wallis one-way ANOVA on ranks. Results: Posterior anal pressures were significantly decreased in sham treated animals compared with controls (p = 0.04). In contrast, mean anal pressures at the four time points were not significantly different between groups (p > 0.05). The defect area of the sham treated group showed irregular muscle bundles, while all three SDF-1 treatment groups show organized muscle bundles, with the most organization in the higher dose groups. Quantification of Masson-stained slides showed no statistically significant differences between groups, but did show increased muscle volume in the area of defect in the treatment groups compared with sham. PGP9.5 and CY3 staining showed increased fluorescence in the higher dose groups compared with sham treatment. Conclusion: A single higher dose of the plasmid encoding SDF-1 may increase muscle volume in the area of a chronic defect. Impact statement Fecal or bowel incontinence as a result of a torn anal sphincter complex remains undetected for many years. The resulting defect does not respond well to surgical repair. Regenerating the anal sphincter complex with functional muscle has been a long-term goal. Stem cells home to a site of a chronic injury and cause regeneration when a cell signaling mechanism is available. Stromal cell-derived factor-1 is one such cytokine that has been well researched by us and others to have this effect. It is easy to use clinically and has been used in other applications in humans and considered safe.

Chemokine therapy for anal sphincter injury in a rat model: a pilot study

INTRODUCTION AND HYPOTHESIS

To determine whether delayed administration of CXCL12 alters anorectal manometric pressures and histology in rats following anal sphincterotomy compared to primary surgical repair alone.

METHODS

Adult female rats were divided into three groups: A, a control group that did not undergo surgery; B, anal sphincterotomy with primary surgical repair; C, anal sphincterotomy with primary surgical repair and intra-sphincteric injection of CXCL12 at 6 weeks post-injury. All rats underwent anal manometry measurements at baseline and at 6 and 12 weeks post-injury. Histologic analysis of the anal sphincters was also performed.

RESULTS

At baseline and 6 weeks, there were no statistically significant differences among D, T_max and P∆ of Groups A, B and C. At 12-week manometry, the total duration of contractions on anal manometry was significantly less in Group C compared to Groups A and B (3.65, 5.5, 5.3 p < 0.01) as was time to peak of contraction at 12 weeks (1.6, 2.1, 3.1, p < 0.01); however, group C had a significantly higher P∆ at 12 weeks compared to Groups A and B (2.25, 1.4, 0.34, p < 0.01). There were no statistically significant differences in the ratio of muscle to collagen at the site of injury; however, muscle fibers were significantly smaller in group C and less per bundle than the other groups.

CONCLUSIONS

Administration of chemokine therapy at 6 weeks post-repair using CXCL12 enhanced the magnitude of anal sphincter contractions in a rat model of anal sphincter injury but decreased overall duration of contraction. Increased anal sphincter contraction magnitude was not explained by histologic differences in explanted specimens.

Stromal cell derived factor 1 plasmid to regenerate the anal sphincters

The aim of this study was to evaluate regeneration of a chronic large anal sphincter defect in a pig model after treatment with a plasmid encoding Stromal Cell Derived Factor-1(SDF-1).

METHODS

Under ethics approved protocol 19 age/weight matched Sinclair mini-pigs were subjected to excision of the posterior 50% of anal sphincter muscle and left to recover for 6 weeks. They were randomly allocated to receive either saline treatment (Saline 1 ml, n = 5), 1 injection of SDF-1 plasmid 2 mg/ml (1 SDF-1, n = 9) or 2 injections of SDF-1, 2 mg/ml each at 2 weeks intervals (2 SDF-1, n = 5). Euthanasia occurred 8 weeks after the last treatment. In vivo outcomes included anal resting pressures done under anesthesia pre-injury, pre-injection and before euthanasia (8 weeks after treatment). Anal ultrasound was done pre injury and pre-euthanasia. Tissues were saved for histology and analyzed quantitatively. Two way ANOVA followed by Holm-Sidak test and one way ANOVA followed by the Tukey test were used for data analysis, p < 0.05 was regarded as significant.

RESULTS

Posterior anal pressures at the 3 time points were not significantly different in the saline group. In contrast, post-treatment pressures in the 1 SDF-1 group pressures were significantly higher than both pre-injury (p = 0.001) and pre-treatment time points (p = 0.003). At the post-treatment time point, both 1 SDF-1 (p = 0.01) and 2 SDF-1 (p = 0.01) groups had significantly higher mean pressures compared to the saline group. Histology showed distortion of normal anatomy with patchy regeneration in the control group while muscle was more organized in both treatment groups.

CONCLUSIONS

Eight weeks after a single or two doses of SDF-1injected into a chronic anal sphincter injury improved resting anal pressures and regenerated muscle in the entire defect. SDF-1 plasmid is effective in treating chronic defects of the anal sphincter in a large animal and could be clinically translated.

Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand?

Anal sphincter incontinence is a chronic disease, which dramatically impairs quality of life and induces high costs for the society. Surgery, considered as the best curative option, shows a disappointing success rate. Stem/progenitor cell therapy is pledging, for anal sphincter incontinence, a substitute to surgery with higher efficacy. However, the published literature is disparate. Our aim was to perform a review on the development of cell therapy for anal sphincter incontinence with critical analyses of its pitfalls. Animal models for anal sphincter incontinence were varied and tried to reproduce distinct clinical situations (acute injury or healed injury with or without surgical reconstruction) but were limited by anatomical considerations. Cell preparations used for treatment, originated, in order of frequency, from skeletal muscle, bone marrow or fat tissue. The characterization of these preparations was often incomplete and stemness not always addressed. Despite a lack of understanding of sphincter healing processes and the exact mechanism of action of cell preparations, this treatment was evaluated in 83 incontinent patients, reporting encouraging results. However, further development is necessary to establish the correct indications, to determine the most-suited cell type, to standardize the cell preparation method and to validate the route and number of cell delivery.

Treatment of faecal incontinence with autologous expanded mesenchymal stem cells: results of a pilot study

AIM

Management of faecal incontinence (FI) remains challenging because no definitive optimal treatment for this condition has yet been determined. Regenerative medicine could be an attractive therapeutic alternative for treating FI. Here, we aimed to determine the safety and feasibility of autologous expanded mesenchymal stem cells derived from adipose tissue (AdMSCs) in the treatment of patients diagnosed with structural FI.

METHOD

This was a randomized, multicentre, triple-blinded, placebo-controlled pilot study conducted at four sites in Spain with 16 adults with FI and a sphincter defect. Autologous AdMSCs were obtained from patients from surgically excised adipose tissue. These patients were intralesionally infused with a single dose of 4 × 10⁷ AdMSCs or a placebo while under anaesthesia. We assessed the safety and feasibility of the treatment as the cumulative incidence of adverse events and the treatment efficacy using the Cleveland Clinic Faecal Incontinence Score, Faecal Incontinence Quality of Life score and Starck criteria to classify sphincter defects and anorectal physiology outcomes.

RESULTS

Adipose tissue extraction, cell isolation and intralesional infusion procedures were successful in all the patients. There was only one adverse event connected to adipose tissue extraction (a haematoma), and none was associated with the injection procedure. There were no significant differences in any of the assessed clinical, manometric or ultrasonographic parameters.

CONCLUSION

This study indicates that this infusion procedure in the anal sphincter is feasible and safe. However, it failed to demonstrate efficacy to treat patients with structural FI.

Effects of local injection and intravenous injection of allogeneic bone marrow mesenchymal stem cells on the structure and function of damaged anal sphincter in rats

Anal sphincter injury leads to damage to the anal structure and functions and has been identified as a major risk factor for fecal incontinence. Bone marrow mesenchymal stem cells (BMSCs) with capacities of multidifferentiation, paracrine, and low immunogenicity have been widely used in tissue repair and regeneration. The primary objective of this research was to compare the effects of different injection therapies of BMSCs on the injured anal sphincters. Ninety-six Sprague-Dawley female rats were randomly divided into four groups (n = 24 each): intravenous injection, local injection, sham operation, and normal control. For the first three groups, 25% removal of the anal sphincter complex was performed and 0.3-ml phosphate-buffered saline (PBS) (containing 10⁷ green fluorescent protein-labeled allogeneic BMSCs) was given accordingly to the treatment group 24 h after operation for 7 consecutive days. The sham operation group was injected with 0.3-ml PBS only. All cases had undergone evaluation in the 1st, 7th, 14th, and 28th postoperative days. The rats were sacrificed on the 28th postoperative day, and the anal sphincters were dissected to be analyzed by morphological examination. At 14 days postoperatively, local injection of BMSC significantly improved the peak contraction pressure, electromyography amplitude, and frequency of the injured anal sphincter compared with tail vein, but there was no significant difference in resting pressure until 28 days after sphincterectomy. Masson staining results confirmed that the local injection group had significantly more new muscles on the wound. BMSC could remarkably improve peak contraction pressure, electromyography amplitude, and muscle fibers on the wound, and local injection is superior to intravenous injection.

Regenerative medicine as a therapeutic option for fecal incontinence: a systematic review of preclinical and clinical studies

BACKGROUND

Fecal incontinence is the uncontrollable loss of stool and has a prevalence of around 7-15%. This condition has serious implications for patients' quality of life. Current treatment options show unsatisfactory results. A novel treatment option is therefore needed.

OBJECTIVE

This systematic review aims to perform a quality assessment and to give a critical overview of the current research available on regenerative medicine as a treatment for fecal incontinence.

STUDY DESIGN

A systematic search strategy was applied in PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, and Cinahl from inception until March of 2018. Studies were found relevant when the animals or patients in the studied group had objectively determined or induced fecal incontinence, and the intervention must have used any kind of cells, stem cells, or biocompatible material, with or without the use of trophic factors. Studies were screened on title and consecutively on abstract for relevance by 2 independent investigators. The risk of bias of preclinical studies was assessed using the SYstematic Review Centre for Laboratory animal Experimentation risk of bias tool for animal studies, and for clinical studies the Cochrane risk of bias tool for randomized trials was used.

RESULTS

In all, 34 preclinical studies and 5 clinical studies were included. Animal species, type of anal sphincter injury, intervention, and outcome parameters were heterogenous. Therefore, a meta-analysis could not be performed. The overall risk of bias of the included studies was high.

CONCLUSION

The efficacy of regenerative medicine to treat fecal incontinence could not be determined due to the high risk of bias and heterogenicity of the available preclinical and clinical studies. The findings of this systematic review may result in improved study design of future studies, which could help the translation of regenerative medicine to the clinic as an alternative to current treatments for fecal incontinence.

Stem cell therapy for faecal incontinence: Current state and future perspectives

Faecal continence is a complex function involving different organs and systems. Faecal incontinence is a common disorder with different pathogeneses, disabling consequences and high repercussions for quality of life. Current management modalities are not ideal, and the development of new treatments is needed. Since 2008, stem cell therapies have been validated, 36 publications have appeared (29 in preclinical models and seven in clinical settings), and six registered clinical trials are currently ongoing. Some publications have combined stem cells with bioengineering technologies. The aim of this review is to identify and summarise the existing published knowledge of stem cell utilization as a treatment for faecal incontinence. A narrative or descriptive review is presented. Preclinical studies have demonstrated that cellular therapy, mainly in the form of local injections of muscle-derived (muscle derived stem cells or myoblasts derived from them) or mesenchymal (bone-marrow- or adipose-derived) stem cells, is safe. Cellular therapy has also been shown to stimulate the repair of both acute and subacute anal sphincter injuries, and some encouraging functional results have been obtained. Stem cells combined with normal cells on bioengineered scaffolds have achieved the successful creation and implantation of intrinsically-innervated anal sphincter constructs. The clinical evidence, based on adipose-derived stem cells and myoblasts, is extremely limited yet has yielded some promising results, and appears to be safe. Further investigation in both animal models and clinical settings is necessary to drawing conclusions. Nevertheless, if the preliminary results are confirmed, stem cell therapy for faecal incontinence may well become a clinical reality in the near future.