Biosutures improve healing of experimental weak colonic anastomoses

The Role of Adipose Tissue Mesenchymal Stem Cells in Colonic Anastomosis Healing in Inflammatory Bowel Disease: Experimental Study in Rats

(1) Background: A surgical operation on an inflamed bowel is, diachronically, a challenge for the surgeon, especially for patients with inflammatory bowel disease. Adipose tissue-derived mesenchymal stromal cells are already in use in clinical settings for their anti-inflammatory properties. The rationale of the current study was to use AdMSCs in high-risk anastomoses to monitor if they attenuate inflammation and prevent anastomotic leak. (2) Methods: a total of 4 groups of rats were subjected to a surgical transection of the large intestine and primary anastomosis. In two groups, DSS 5% was administered for 7 days prior to the procedure, to induce acute intestinal inflammation. After the anastomosis, 5 × 106 autologous AdMSCs or an acellular solution was injected locally. Macroscopic evaluation, bursting pressure, hydroxyproline, and inflammatory cytokine expression were the parameters measured on the 8th post-operative day. (3) Results: Significantly less intra-abdominal complications, higher bursting pressures, and a decrease in pro-inflammatory markers were found in the groups that received AdMSCs. No difference in VEGF expression was observed on the 8th post-operative day. (4) Conclusions: AdMSCs attenuate inflammation in cases of acutely inflamed anastomosis.

Stem cell therapy applied for digestive anastomosis: Current state and future perspectives

BACKGROUND

Digestive tract resections are usually followed by an anastomosis. Anastomotic leakage, normally due to failed healing, is the most feared complication in digestive surgery because it is associated with high morbidity and mortality. Despite technical and technological advances and focused research, its rates have remained almost unchanged the last decades. In the last two decades, stem cells (SCs) have been shown to enhance healing in animal and human studies; hence, SCs have emerged since 2008 as an alternative to improve anastomoses outcomes.

AIM

To summarise the published knowledge of SC utilisation as a preventative tool for hollow digestive viscera anastomotic or suture leaks.

METHODS

PubMed, Science Direct, Scopus and Cochrane searches were performed using the key words "anastomosis", "colorectal/colonic anastomoses", "anastomotic leak", "stem cells", "progenitor cells", "cellular therapy" and "cell therapy" in order to identify relevant articles published in English and Spanish during the years of 2000 to 2021. Studies employing SCs, performing digestive anastomoses in hollow viscera or digestive perforation sutures and monitoring healing were finally included. Reference lists from the selected articles were reviewed to identify additional pertinent articles.Given the great variability in the study designs, anastomotic models, interventions (SCs, doses and vehicles) and outcome measures, performing a reliable meta-analysis was considered impossible, so we present the studies, their results and limitations.

RESULTS

Eighteen preclinical studies and three review papers were identified; no clinical studies have been published and there are no registered clinical trials. Experimental studies, mainly in rat and porcine models and occasionally in very adverse conditions such as ischaemia or colitis, have been demonstrated SCs as safe and have shown some encouraging morphological, functional and even clinical results. Mesenchymal SCs are mostly employed, and delivery routes are mainly local injections and cell sheets followed by biosutures (sutures coated by SCs) or purely topical. As potential weaknesses, animal models need to be improved to make them more comparable and equivalent to clinical practice, and the SC isolation processes need to be standardised. There is notable heterogeneity in the studies, making them difficult to compare. Further investigations are needed to establish the indications, the administration system, potential adjuvants, the final efficacy and to confirm safety and exclude definitively oncological concerns.

CONCLUSION

The future role of SC therapy to induce healing processes in digestive anastomoses/sutures still needs to be determined and seems to be currently far from clinical use.

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.

Rat model of anal sphincter injury and two approaches for stem cell administration

AIM

To establish a rat model of anal sphincter injury and test different systems to provide stem cells to injured area.

METHODS

Adipose-derived stem cells (ASCs) were isolated from BDIX rats and were transfected with green fluorescent protein (GFP) for cell tracking. Biosutures (sutures covered with ASCs) were prepared with 1.5 x 106 GFP-ASCs, and solutions of 106 GFP-ASCs in normal saline were prepared for injection. Anorectal normal anatomy was studied on Wistar and BDIX female rats. Then, we designed an anal sphincter injury model consisting of a 1-cm extra-mucosal miotomy beginning at the anal verge in the anterior middle line. The sphincter lesion was confirmed with conventional histology (hematoxylin and eosin) and immunofluorescence with 4', 6-diamidino-2-phenylindole (commonly known as DAPI), GFP and α-actin. Functional effect was assessed with basal anal manometry, prior to and after injury. After sphincter damage, 36 BDIX rats were randomized to three groups for: (1) Cell injection without repair; (2) biosuture repair; and (3) conventional suture repair and cell injection. Functional and safety studies were conducted on all the animals. Rats were sacrificed after 1, 4 or 7 d. Then, histological and immunofluorescence studies were performed on the surgical area.

RESULTS

With the described protocol, biosutures had been covered with at least 820000-860000 ASCs, with 100% viability. Our studies demonstrated that some ASCs remained adhered after suture passage through the muscle. Morphological assessment showed that the rat anal anatomy is comparable with human anatomy; two sphincters are present, but the external sphincter is poorly developed. Anal sphincter pressure data showed spontaneous, consistent, rhythmic anal contractions, taking the form of "plateaus" with multiple twitches (peaks) in each pressure wave. These basal contractions were very heterogeneous; their frequency was 0.91-4.17 per min (mean 1.6980, SD 0.57698), their mean duration was 26.67 s and mean number of peaks was 12.53. Our morphological assessment revealed that with the aforementioned surgical procedure, both sphincters were completely sectioned. In manometry, the described activity disappeared and was replaced by a gentle oscillation of basal line, without a recognizable pattern. Surprisingly, these findings appeared irrespective of injury repair or not. ASCs survived in this potentially septic area for 7 d, at least. We were able to identify them in 84% of animals, mainly in the muscular section area or in the tissue between the muscular endings. ASCs formed a kind of "conglomerate" in rats treated with injections, while in the biosuture group, they wrapped the suture. ASCs were also able to migrate to the damaged zone. No relevant adverse events or mortality could be related to the stem cells in our study. We also did not find unexpected tissue growths.

CONCLUSION

The proposed procedure produces a consistent sphincter lesion. Biosutures and injections are suitable for cell delivery. ASCs survive and are completely safe in this clinical setting.

Reduction of carcinomatosis risk using icodextrin as a carrier solution of intraperitoneal oxaliplatin chemotherapy

There is no standard treatment in patients with high risk metachronous peritoneal carcinomatosis (PC) in colonic cancer, as perforated tumour or synchronous ovarian metastasis. Icodextrin 4% (ICDX), presently used to prevent postoperative abdominal adhesions, could inhibit the coactivation of the tumour cells and the microenvironment cells, associated with the development of PC. The aim of this study was to inhibit the formation of the PC in a murine model mimicking surgical situation using ICDX and intraperitoneal (IP) prophylactic chemotherapy. We created a model of growing PC in mice using cells of murine colonic cancer CT26. Cells and treatments were injected simultaneously. Five groups were created: CT26 (control group), CT26 + ICDX (ICDX group), CT26 + chemotherapy (oxaliplatin and 5FU) (chemo group), CT26 + chemotherapy + ICDX (ICDX chemo group), ICDX (toxicity group). At day 15, PC was evaluated with rodents PCI. In the chemo group, PCI was significantly lower than in the control group (3.2 versus 8.4, p = 0.02). ICDX had a synergetic effect on PC with chemotherapy; indeed PCI in ICDX chemo group was lower than in chemo group (1.4 versus 3.2, p = 0.04). There was no morbidity linked to ICDX in toxicity group. Safety of ICDX needs to be verified, particularly on colonic anastomosis before ICDX associated to IP chemotherapy could be used as a preventive treatment of PC in high risk patients. This prophylactic treatment is easy to use and would be administrated at the end of a curative surgery for a colonic cancer.

An Experimental Study on the Use of Calcium Alginate to Heal Colonic Anastomoses

BACKGROUND

Anastomotic leak is considered the major complication following abdominal surgery. In recent years, the use of a variety of sealing materials for the prevention of leaks has been analyzed. Different biomaterials have been employed as scaffolds to favour tissue repair and regeneration. Among these materials we must mention alginate, a natural polymer with different applications as temporary supporting matrix. The aim of the present study is to evaluate the behavior of both alginate-impregnated sutures and lyophilized alginate sponges in the healing process of colonic anastomes using an experimental animal model.

MATERIAL AND METHODS

A preliminary study was undertaken to select the adequate scaffold. Animals (n = 45) were distributed into three groups: control (colonic anastomosis using non-continuous 5-0 Polyglactin 910 suture), suture (colonic anastomosis using suture impregnated with alginate gel at 4%) and sponge (colonic anastomosis using suture reinforced with lyophilized alginate sponge). The macroscopic and histological variables were assessed at 4, 8 and 12 days after surgical intervention.

RESULTS

No statistically significant differences have been observed between the groups during the analysis of macroscopic variables. Animals with sponge implantation showed a greater degree of epithelial reepithalization, less acute and chronic inflammation and greater collagen deposit.

CONCLUSIONS

The use of lyophilized alginate sponges to reinforce colonic anastomoses in an animal model reduces inflammation and promotes the earlier formation of greater collagen deposits without increasing the number of adhesions or the incidence of stenosis.

Systemic treatment of acute liver failure with adipose derived stem cells

PURPOSE OF THE STUDY

The definitive treatment for liver failure is, currently, liver transplantation. Research into other possible treatments, focused on achieving regeneration of the liver parenchyma, have led to the development of methods to generate hepatocytes from stem cells. In our study, we transplant allogenic adipose-derived stem cells (ASCs), not previously differentiated to hepatocytes, to treat acute liver failure induced by intraperitoneal administration of carbon tetrachloride (CCl4) in a Sprague-Dawley rat model.

MATERIAL AND METHODS

The ASCs were delivered via the tail vein, having previously been labeled with PKH26, a fluorescent membrane marker. Two control groups were established, Group 1(n = 15) consisting of olive oil (5 mL/kg) and Group 2(n = 15): 1 × 10(6) PKH26-labeled ASCs. Further, two study groups, Group 3(n = 30): CCl4 dissolved in olive oil and Group 4(n = 30): CCl4 dissolved in olive oil and 1 × 10(6) PKH26-labeled ASCs completed the experimental design.

RESULTS

Blood samples were analyzed, finding AST and ALT levels significantly higher in treatment over control groups at 24 and 48 hours. The mortality rates were statistically different between control groups and Group 3 (Group 1-3 p = .04, Group 2-3 p = .04) and between Groups 3 and 4 (p = .02). Examining the liver parenchyma, a significantly higher number of ASCs were observed in Group 4 than in Group 2 at all time points (p = .00).

CONCLUSIONS

The intravenous injection of allogenic ASCs in this model of CCl4-induced liver failure reduced the mortality in treated animals. ASCs injected in the rat tail vein were found in the liver in animals with induced acute liver failure.

Sutures enriched with adipose-derived stem cells decrease the local acute inflammation after tracheal anastomosis in a murine model

OBJECTIVES

Local inflammatory reaction and tension are the main causes of postoperative complications after tracheal surgery. Adipose-derived stem cells (ASCs) are known to have immunomodulatory activity. The exact mechanism of this activity is not known, although it is possible that they modulate the function of different cells involved in the immune response. Little is known of their impact on acute inflammation, especially in the problematic tracheal area. We aimed to study the effect of ASCs applied locally in an animal model of tracheal resection and anastomosis.

METHODS

ASCs from the subcutaneous fat of BDIX rats were infected for expression of the enhanced green fluorescent protein (eGFP) and were cultured with Polyglactin 910 sutures to obtain biosutures (ASC-coated sutures). After tracheal resection, 90 BDIX rats (syngeneic, autologous model) underwent anastomosis with biosutures (1.5 10(6) cells/biosuture [Group 1] or 0.5 10(6) cells/biosuture [Group 2]) or conventional sutures (Group 3). The animals were killed after 1, 4, 10, 30 or 60 days and histological and immunofluorescence studies were performed on the anastomotic areas. Inflammatory cell densities were graded semiquantitatively by the pathologist in a blinded fashion.

RESULTS

In the early period (1 and 4 days), the biosuture groups presented an atypical pattern of acute inflammation, characterized by the almost complete absence of neutrophils, and the presence of abundant lymphocytes and plasma cells, compared with the control group (P < 0.05). Moreover, abundant macrophages/monocytes were immunolocated around blood vessels near the biosutures and between biosuture threads 1 day after anastomosis, whereas the presence of macrophages/monocytes in animals treated with conventional sutures was discrete (P < 0.05). No differences were observed in the later period. No side effects in the biosuture groups were found.

CONCLUSIONS

Biosutures are a comfortable way of stem cell delivery to the surgical field without modification of the operative protocol. ASCs suppress the local acute inflammatory reaction (increased macrophage migration and decreased neutrophil infiltration) in the tracheal anastomosis and cause an early switch from acute to chronic inflammation.

The effect of adipose-derived stem cells on augmentation ileocystoplasty: A pilot study

Objectives

Incorporation of intestinal tissue into urinary tract elicits many metabolic and mechanical complications due to anatomical and physiological differences. Adipose-derived stem cells (ADSCs) improve vascularity and functional outcomes by a paracrine mechanism. In a pilot study we investigated whether ADSCs can survive in the augmented bladder and improve its function.

Materials and methods

Autologous ADSCs were harvested from rat paragonadal fat and cultured before injection into a rat model of augmentation ileocystoplasty (study group). Control augmented bladders were injected with cell-free saline. Eight weeks later, rats underwent abdominal ultrasonography for upper tract changes and were examined by conscious cystometry to determine bladder function. After extirpation, augmented bladders were examined using Masson trichrome staining for connective tissue and muscle content, immunohistochemistry for α-smooth muscle actin, and rat endothelial cell antigen staining for endothelial cells. Changes in the extracellular matrix were assessed by determining the elastin content. ADSCs were labelled and tracked by 5-ethynyl-2-deoxyuridine nuclear staining.

Results

Abdominal ultrasonography showed better preservation of upper tract function in the ADSC group than in the saline-treated group (P = 0.007). After 2 months there were no differences in the variables assessed by conscious cystometry between the ADSC and saline-treated groups. However, the bladder weight was significantly greater in the ADSC-treated group. On immunohistochemistry, the implanted ADSCs survived up to 8 weeks but did not transdifferentiate into smooth muscle or endothelial cells.

Conclusion

These results suggested a potential role of ADSCs in modifying the intestinal segment in augmented bladders; this role has to be further elucidated.