Mesenchymal stem cells improve the healing of ischemic colonic anastomoses (experimental study). Langenbecks Arch Surg. 2011;396:115-126. [PMID: 20953879 DOI: 10.1007/s00423-010-0717-z]

Experimental models of high-risk bowel anastomosis in rats: A systematic review

BACKGROUND

Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity, that negatively affect the patients' quality of life. Experimental studies play an important role in understanding the pathophysiological background of anastomotic healing and there are still many fields that require further investigation. Knowledge drawn from these studies can lead to interventions or techniques that can reduce the risk of anastomotic leak in patients with high-risk features. Despite the advances in experimental protocols and techniques, designing a high-quality study is still challenging for the investigators as there is a plethora of different models used.

AIM

To review current state of the art for experimental protocols in high-risk anastomosis in rats.

METHODS

This systematic review was performed according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. To identify eligible studies, a comprehensive literature search was performed in the electronic databases PubMed (MEDLINE) and Scopus, covering the period from conception until 18 October 2023.

RESULTS

From our search strategy 102 studies were included and were categorized based on the mechanism used to create a high-risk anastomosis. Methods of assessing anastomotic healing were extracted and were individually appraised.

CONCLUSION

Anastomotic healing studies have evolved over the last decades, but the findings are yet to be translated into human studies. There is a need for high-quality, well-designed studies that will help to the better understanding of the pathophysiology of anastomotic healing and the effects of various interventions.

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.

Bone Regeneration Using Autologous Adipose-Derived Stem Cell Spheroid Complex

Bone defects require reconstruction using various biomaterials or non-biological materials. Stem cell spheroids can be used for scaffold-free approaches for osteogenesis. We set up a culture method for creating an optimal osteogenic adipose-derived stem cell (ADSC) spheroid complex by measuring the expression of protein in a sequential series of culture media. After culturing ADSC spheroids for 24 hours in DMEM, the spheroids were cultured in ascorbic acid-containing medium for five days followed by osteoblast differentiation medium. One day after exchanging to osteoblast differentiation medium, spheroids were collected and cultured for four days to obtain a spheroid complex. Each culture period was determined by analyzing the expression of collagen type I, alkaline phosphatase and integrin α5 to maximize the activity of ADSC spheroids. The expression of collagen type I increased significantly in ascorbic acid-containing medium (p < 0.05) compared with control medium on day five, suggesting that culturing spheroids in ascorbic acid increases collagen synthesis. RNA was extracted from ADSC spheroids after 1, 3, 5, and 7 days in each medium and RT-PCR was performed to measure integrin α5 expression. The expression was transiently high on the first day of osteoblast differentiation culture and then gradually decreased. Osteoblast differentiation medium enhanced cell adhesion in spheroids. An in vivo study confirmed the osteogenic potential of the ADSC spheroid complex created by the established protocol. The ADSC spheroid complex stimulated bone regeneration and will be applied to the treatment of large bone defects.

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.

The use of mesenchymal stem cells in animal models for gastrointestinal anastomotic leak: A systematic review

AIM

Anastomotic leak is the most feared complication of gastrointestinal surgery. Mesenchymal stem cell technology is used clinically to promote wound healing; however, the safety and efficacy of this technology on anastomotic healing has yet to be defined. The aim of this study was to investigate whether mesenchymal stem cells confer any benefit when applied to animal models for gastrointestinal anastomotic leak, identify the methodology and how efficacy is assessed.

METHODS

The MEDLINE, EMBASE, WebofScience and Cochrane Library databases were interrogated between 1 January1947 to 1 May 2020. All studies where mesenchymal stem cells were applied to laboratory animal leak models to demonstrate a healing effect were considered. All experimental and histological outcomes were examined. Compliance to ARRIVE and current International Consensus was assessed.

RESULTS

A total of 1205 studies were screened. Twelve studies reported on 438 gastrointestinal anastomoses in four species using 11 models; seven in the colon. No studies utilised a model with a known leak rate. Significant variance was observed in histological outcomes with efficacy demonstrated in five out of 12 studies. One study demonstrated a benefit in leak rate. Colorectal studies had a greater median ARRIVE compliance, 60.8% (IQR 63.2-64.5) compared to noncolorectal 45.4% (IQR 43.8-49.0).

CONCLUSIONS

Mesenchymal stem cell delivery to an animal anastomosis is safe and feasible. Use may confer benefit but findings are currently limited to surrogate histological outcomes. There is consistency in outcome measures reported but variance in how this is assessed. Poor compliance to ARRIVE but good compliance to current international consensus in leak models of the colon was observed.

The application of regenerative medicine in colorectal surgery

Tissue reconstruction and regeneration represent one of the greatest challenges in any surgical field. Regenerative medicine combined with stem cell-based therapy is a novel and promising field of medicine. Stem cells possess the ability to differentiate into specialized cells and to decrease inflammation and therefore can play a role in repair or regeneration of damaged tissues. Colorectal surgery often deals with infected, poorly vascularized, radiated, and inflamed tissue, as well as instances where imperfect healing might have grave implications. This problem has led researchers to study utilizing stem cells in many colorectal conditions, such as anastomotic healing, perianal fistulae, rectovaginal fistulae, anal fissure, and fecal incontinence. The purpose of this review was to discuss prominent studies that explored stem cells utilization in treating different colorectal pathologies.

Human Oral Mucosal Stem Cells Reduce Anastomotic Leak in an Animal Model of Colonic Surgery

BACKGROUND

Anastomotic leak is regarded as one of the most feared complications of bowel surgery; avoiding leaks is a major priority. Attempts to reduce or eliminate leaks have included alternate anastomotic techniques. Human oral mucosa stem cells (hOMSC) are self-renewing and expandable cells derived from buccal mucosa. Studies have shown that hOMSC can accelerate tissue regeneration and wound healing. The objective of this study was to evaluate whether hOMSC can decrease anastomotic leak rates in a murine model of colon surgery.

METHODS

Two experiments were performed. In the first study, mice underwent colonic anastomosis using five interrupted sutures. hOMSC (n = 7) or normal saline (NS; n = 17) was injected into the colon wall at the site of the anastomosis. To evaluate whether hOMSC can impact anastomotic healing, the model was stressed by repeating the first experiment, reducing the number of sutures used for the construction of the anastomosis from five to four. Either hOMSC (n = 8) or NS (n = 20) was injected at the anastomosis. All mice that survived were sacrificed on postoperative day 7. Anastomotic leak rate, mortality, daily weight, and daily wellness scores were compared.

RESULTS

In the five-suture anastomosis, there were no differences in anastomotic leak rate, mortality, or daily weight. Mice that received hOMSC had significantly higher wellness scores on postoperative day 2 (p < 0.05). In the four-suture anastomosis, there was a significant decrease in leak rate (70% [NS] vs. 25% [hOMSC], p = 0.029) and higher wellness scores in mice that received hOMSC (p < 0.05).

CONCLUSION

Our study suggests that injecting hOMSC at the colonic anastomosis can potentially reduce anastomotic leak and improve postoperative wellness in a murine model of colon surgery.

Locally Transplanted Adipose Stem Cells Reduce Anastomotic Leaks in Ischemic Colorectal Anastomoses: A Rat Model

BACKGROUND

Anastomotic leakage remains a dreaded complication after colorectal surgery. Stem-cell-based therapies have been shown to increase angiogenesis and cell proliferation.

OBJECTIVE

The purpose of this research was to investigate the use of adipose-derived stem cells on the healing of ischemic colonic anastomoses in a rat model.

DESIGN

This is an animal research study using xenotransplantation.

SETTINGS

Male Wistar rats (300-400 g, n = 48) were purchased from a licensed breeder.

PATIENTS

Adipose stem cells were isolated from the subcutaneous fat of healthy human donors.

INTERVENTIONS

The rats underwent laparotomy with creation of an ischemic colorectal anastomosis created by ligation of mesenteric vessels. The animals were divided into 3 groups: control group with an ischemic anastomosis, vehicle-only group in which the ischemic anastomosis was treated with an absorbable gelatin sponge, and a treatment group in which the ischemic anastomosis was treated with an absorbable gelatin sponge plus adipose stem cells. Animals were killed at postoperative days 3 and 7.

MAIN OUTCOME MEASURES

Anastomotic leakage was defined as the finding of feculent peritonitis or perianastomotic abscess on necropsy. Rat mRNA expression was measured using real-time polymerase chain reaction.

RESULTS

Adipose-derived stem cells significantly decreased anastomotic leakage when compared with control at both postoperative days 3 (25.0% vs 87.5%; p = 0.02) and 7 (25.0% vs 87.5%; p = 0.02). The use of an absorbable gelatin sponge alone had no effect on anastomotic leakage when compared with control and postoperative days 3 or 7. We found that stem cell-treated animals had a 5.9-fold and 7.4-fold increase in the expression of vascular endothelial growth factor when compared with control at 3 and 7 days; however, this difference was not statistically significant when compared with the absorbable gelatin sponge group.

LIMITATIONS

This is a preclinical animal research study using xenotransplantation of cultured stem cells.

CONCLUSIONS

Locally transplanted adipose stem cells enhance the healing of ischemic colorectal anastomoses and may be a novel strategy for reducing the risk of anastomotic leakage in colorectal surgery. See Video Abstract at http://links.lww.com/DCR/B203. EL TRANSPLANTE LOCAL DE CÉLULAS MADRE ADIPOSAS REDUCE LA FUGA ANASTOMÓTICA EN LAS SUTURAS COLORRECTALES ISQUÉMICAS: MODELO EN RATAS: Las fugas anastomóticas son una complicación pusilánime después de toda cirugía colorrectal. Se ha demostrado que el tratamiento con células madre aumenta la angiogénesis y la proliferación celular.Investigar el uso de células madre derivadas de tejido adiposo en la cicatrización de una anastomosis colónica isquémica basada en ratas como modelo.Estudio de investigación en animales utilizando xenotrasplantes.Adquisición de típicas ratas de laboratorio raza Wistar, todas machos (300-400 g, n = 48) de un criadero autorizado.Aislamiento de células madre de tipo adiposo del tejido celular subcutáneo en donantes humanos sanos.Las ratas se sometieron a laparotomía con la creación de una anastomosis colorrectal isquémica obtenida mediante ligadura controlada de los vasos mesentéricos correspondientes. Los animales se dividieron en tres grupos: grupo de control con anastomosis isquémica, grupo de vehículo único en el que la anastomosis isquémica se trató con una esponja de gelatina absorbible, y un grupo de tratamiento en el que la anastomosis isquémica se trató con una esponja de gelatina absorbible asociada a un vástago adiposo de células madre. Los animales fueron sacrificados el POD3 y el POD7.La fuga anastomótica fué definida como el hallazgo de peritonitis fecaloidea o absceso perianastomótico a la necropsia. La expresión de RNAm de las ratas se midió usando PCR en tiempo real.Las células madre derivadas de tejido adiposo disminuyeron significativamente la fuga anastomótica en comparación con el grupo control tanto en el POD3 (25% frente a 87.5%, p = 0.02) como en el POD7 (25% frente a 87.5%, p = 0.02). El uso de una esponja de gelatina absorbible sola, no tuvo efecto sobre la fuga anastomótica en comparación con los controles el POD3 o el POD7. Descubrimos que los animales tratados con células madre adiposas tenían un aumento de 5,9 y 7,4 veces en la expresión de VEGF en comparación con el control a los 3 y 7 días, respectivamente; sin embargo, esta diferencia no fue estadísticamente significativa en comparación con el grupo de esponja de gelatina absorbible.Este es un estudio preclínico de investigación en animales que utiliza xenotrasplantes de células madre adiposas cultivadas.Las células madre de tipo adiposo trasplantadas localmente mejoran la cicatrisación en casos de anastomosis colorrectales isquémicas, y podrían convertirse en una nueva estrategia para reducir el riesgo de fugas anastomóticas en casos de cirugía colorrectal. Consulte Video Resumen en http://links.lww.com/DCR/B203. (Traducción-Dr Xavier Delgadillo).

Comparison of mesenchymal stem cell sheets and chondrocyte sheets in a rabbit growth plate injury model

Background/aim

The treatment of posttraumatic deformities and differences in length between the extremities resulting from physeal injury remains controversial. The aims of this study were to compare the efficacy of tissue-engineered, monolayer, and allogeneic mesenchymal stem cell sheets and chondrocyte sheets for physeal arrest treatment and to investigate cell sheet technology as a novel method for cell transplantation in physeal cartilage repair.

Materials and methods

A proximal tibial physeal injury was induced in New Zealand rabbits. Allogeneic mesenchymal stem cells (MSCs) and chondrocytes were cultured in temperature-responsive culture dishes and applied to the iatrogenic partial growth plate defects in single-sheet grafts (cell sheets). Treatment efficacy was determined using radiological measurements, as well as histological and immunohistochemical staining.

Results

Treatment with MSCs and chondrocytes prevented endochondral ossification in the physeal plate, and bone growth resumed after treatment in both the MSC and chondrocyte cell groups. We found significant differences in radiological evaluations between pre- and posttreatment measurements in both MSC and chondrocyte groups. Transplanted cells were observed in the damaged area in both of the groups, which differentiated in the direction of growth plate cartilage.

Conclusion

Our results support the hypothesis that MSC or chondrocyte transplantation using the cell-sheet technique described in the present study aids in the regeneration of cartilage tissue during physeal arrest after growth plate damage.

Anastomotic leak in colorectal cancer patients: New insights and perspectives

Anastomotic leak (AL) remains a potentially life-threatening sequela of colorectal surgery impacting on mortality, short- and long-term morbidity, quality of life, local recurrence (LR) and disease-free survival. Despite technical improvements and the identification of several surgery- and patient-related factors associated to the risk of AL, its incidence has not significantly changed over time. In this context, the clarification of the mechanisms underlying anastomotic healing remains an important unmet need, crucial for improving patients' outcomes. This review concentrates on novel key findings in the etiopathogenesis of AL, how they can contribute in determining LR, and measures which may contribute to reducing its incidence. AL results from a complex, dynamic interplay of several factors and biological processes, including host genetics, gut microbiome, inflammation and the immune system. Many of these factors seem to act in concert to drive both AL and LR, even if the exact mechanisms remain to be elucidated. The next generation sequencing technology, including the microbial metagenomics, could lead to tailored bowel preparations targeting only those pathogens that can cause AL. Significant progress is being made in each of the reviewed areas, moving toward translational and targeted therapeutic strategies to prevent the difficult complication of AL.

Mesenchymal Stem Cells Combined with Tissue Fusion Technology Promoted Wound Healing in Porcine Bowel Anastomosis

Objective

To evaluate the possible biological effect of allogenic mesenchymal stem cells (MSCs) combined with tissue fusion technology on the anastomosis.

Methods

Sixteen pigs were divided into a 7 d group and 14 d group, each of which was further subdivided into an MSC-treated group and a control group. Five anastomoses per animal were established using LigaSure ForceTriad (Covidien, MA, USA), a tissue sealing system. Cell migration and tissue-specific differentiation potency, in addition to potential cytokine and genetic changes, were investigated.

Results

There were no significant between-group differences in postoperative complications and anastomosis burst pressure. The number of proliferating cell nuclear antigen- (PCNA-) positive cells was significantly higher in the MSC-treated group as compared with that in the control group (P = 0.021). Labeled MSCs were found in the mucosal layer, villus, and lamina propria, as well as in the lamina muscularis mucosae, where they exhibited characteristics of smooth muscle cells.

Conclusions

Grafted MSCs significantly promoted epithelial and connective cell proliferation and maintained their cell migration capacity and differentiation potential in the fused anastomotic tissues, without causing severe postoperative complications.

Adipose-Derived Mesenchymal Stromal Cells Improve the Healing of Colonic Anastomoses Following High Dose of Irradiation Through Anti-Inflammatory and Angiogenic Processes

Cancer patients treated with radiotherapy (RT) could develop severe late side effects that affect their quality of life. Long-term bowel complications after RT are mainly characterized by a transmural fibrosis that could lead to intestinal obstruction. Today, surgical resection is the only effective treatment. However, preoperative RT increases the risk of anastomotic leakage. In this study, we attempted to use mesenchymal stromal cells from adipose tissue (Ad-MSCs) to improve colonic anastomosis after high-dose irradiation. MSCs were isolated from the subcutaneous fat of rats, amplified in vitro, and characterized by flow cytometry. An animal model of late radiation side effects was induced by local irradiation of the colon. Colonic anastomosis was performed 4 wk after irradiation. It was analyzed another 4 wk later (i.e., 8 wk after irradiation). The Ad-MSC-treated group received injections several times before and after the surgical procedure. The therapeutic benefit of the Ad-MSC treatment was determined by colonoscopy and histology. The inflammatory process was investigated using Fluorine-182-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography and Computed Tomography (¹⁸F-FDG-PET/CT) imaging and macrophage infiltrate analyses. Vascular density was assessed using immunohistochemistry. Results show that Ad-MSC treatment reduces ulcer size, increases mucosal vascular density, and limits hemorrhage. We also determined that 1 Ad-MSC injection limits the inflammatory process, as evaluated through ¹⁸F-FDG-PET-CT (at 4 wk), with a greater proportion of type 2 macrophages after iterative cell injections (8 wk). In conclusion, Ad-MSC injections promote anastomotic healing in an irradiated colon through enhanced vessel formation and reduced inflammation. This study also determined parameters that could be improved in further investigations.

Imaging of extracellular vesicles derived from human bone marrow mesenchymal stem cells using fluorescent and magnetic labels

Background

Mesenchymal stem cells have been shown therapeutic in various neurological disorders. Recent studies support the notion that the predominant mechanism by which MSCs act is through the release of extracellular vesicles (EVs). EVs seem to have similar therapeutic activity as their cellular counterparts and may represent an interesting alternative standalone therapy for various diseases. The aim of the study was to optimize the method of EV imaging to better understand therapeutic effects mediated by EVs.

Methods

The fluorescent lipophilic stain PKH26 and superparamagnetic iron oxide nanoparticles conjugated with rhodamine (Molday ION Rhodamine B™) were used for the labeling of vesicles in human bone marrow MSCs (hBM-MSCs). The entire cycle from intracellular vesicles to EVs followed by their uptake by hBM-MSCs has been studied. The identity of vesicles has been proven by antibodies against: anti-CD9, -CD63, and -CD81 (tetraspanins). NanoSight particle tracking analysis (NTA), high-resolution flow cytometric analysis, transmission electron microscopy (TEM), ELYRA PS.1 super-resolution microscopy, and magnetic resonance imaging (MRI) were used for the characterization of vesicles.

Results

The PKH26 and Molday ION were exclusively localized in intracellular vesicles positively stained for EV markers: CD9, CD63, and CD81. The isolated EVs represent heterogeneous population of various sizes as confirmed by NTA. The TEM and MRI were capable to show successful labeling of EVs using ION. Co-culture of EVs with hBM-MSCs revealed their uptake by cells in vitro, as visualized by the co-localization of PKH26 or Molday ION with tetraspanins inside hBM-MSCs.

Conclusion

PKH26 and Molday ION seem to be biocompatible with EVs, and the labeling did not interfere with the capability of EVs to re-enter hBM-MSCs during co-culture in vitro. Magnetic properties of IONs provide an additional advantage for the imaging of EV using TEM and MRI.

A canine liver fibrosis model to develop a therapy for liver cirrhosis using cultured bone marrow-derived cells

We have been developing a therapy for liver cirrhosis using cultured autologous bone marrow-derived mesenchymal stem cells (BMSCs). Before human clinical trials can be considered, the safety and efficacy of BMSC infusion in medium to large animals must be confirmed; thus, we developed a canine liver fibrosis model. A small amount of bone marrow fluid was aspirated from the canine humerus to assess the characteristics of BMSCs. We implanted a venous catheter in the stomach and a subcutaneous infusion port in the back of the neck of each canine. Repeated injection of CCl₄ through the catheter was performed to induce liver cirrhosis. After 10 weeks of CCl₄ injection, eight canines were equally divided into two groups: no cell infusion (control group) and autologous BMSC infusion through the peripheral vein (BMSC group). A variety of assays were carried out before and 4 weeks after the infusion. The area of liver fibrosis stained with sirius red was significantly reduced in the BMSC group 4 weeks after BMSC infusion, consistent with a significantly shortened half-life of indocyanine green and improved liver function. Conclusion: We established a useful canine liver fibrosis model and confirmed that cultured autologous BMSC infusion improved liver fibrosis without adverse effects. (Hepatology Communications 2017;1:691-703).

Comparison of the early period effects of bone marrow-derived mesenchymal stem cells and platelet-rich plasma on the Achilles tendon ruptures in rats

INTRODUCTION

This study aims to histopathologically, biomechanically, and immunohistochemically compare the fourth-week efficiencies of local platelet-rich plasma (PRP) and bone marrow-derived mesenchymal stem cell (rBM-MSC) treatments of the Achilles tendon ruptures created surgically in rats.

MATERIALS AND METHODS

The study included 35 12-month-old male Sprague Dawley rats, with an average weight of 400-500 g. Five rats were used as donors for MSC and PRP, and 30 rats were separated into MSC, PRP, and control groups (n = 10). The Achilles tendons of the rats were cut transversely, the MSC from bone marrow was administered to the MSC group, the PRP group received PRP, and the control group received physiological saline to create the same surgical effect. In previous studies, it was shown that this physiological saline does not have any effect on tendon recovery. Thirty days after the treatment, the rats were sacrificed and their Achilles tendons were examined histopathologically, immunohistochemically, and biomechanically.

RESULTS

The use of rBM-MSC and PRP in the Achilles tendon ruptures when the tendon is in its weakest phase positively affected the recovery of the tendon in histopathologic, immunohistochemical, and biomechanical manners compared to the control group (p < 0.05). While the levels of pro-inflammatory cytokines TNF-α, IFNγ, and IL 1β were significantly low, the levels of anti-inflammatory cytokines and growth factors playing key roles in tendon recovery, such as IL2, VEGF, transforming growth factor-beta, and HGF, were significantly higher in the MSC group than those of the PRP and control groups (p < 0.05). In the MSC group, the [Formula: see text] (mm) value was significantly higher (p ˂ 0.05) than that in the PRP and control groups.

CONCLUSION

rBM-MSC and PRP promote the recovery of the tendon and increase its structural strength. The use of PRP and MSC provides hope for the treatment of the Achilles tendon ruptures that limit human beings' functionalities and quality of life, particularly for athletes. It is thought that the use of MSC can be more effective for tendon healing; hence, more extensive and advanced studies are needed on this topic.

Therapeutic improvement of colonic anastomotic healing under complicated conditions: A systematic review

AIM: To identify therapeutic agents for the prophylaxis of gastrointestinal anastomotic leakage (AL) under complicated conditions.

METHODS: The PubMed and EMBASE databases were searched for English articles published between January 1975 and September 2014. Studies with the primary purpose of improving anastomotic healing in the colon or rectum under complicated preoperative and/or intraoperative conditions were included. We excluded studies investigating the adverse effects or risk assessment of an active intervention. Furthermore, investigations of biophysical materials, sealants, electrical stimulation and nutrients were excluded. The primary study outcome was biomechanical anastomotic strength or AL. The meta-analysis focused on therapeutic agents that were investigated in one animal model using the same outcome by at least three independent research groups.

RESULTS: The 65 studies included were divided into 7 different complicated animal models: Bowel ischemia, ischemia/reperfusion, bowel obstruction, obstructive jaundice, peritonitis, chemotherapy and radiotherapy. In total, 48 different therapeutic compounds were examined. The majority of investigated agents (65%) were reported as beneficial for anastomotic healing. Twelve of the agents (25%) were tested more than once in the same model, whereas 13 (27%) of the agents were tested in two or more models of complicated healing. Two therapeutic agents met our inclusion criteria for the meta-analysis. Postoperative hyperbaric oxygen therapy significantly increased anastomotic bursting pressure in ischemic colon anastomoses by a mean of 28 mmHg (95%CI: 17 to 39 mmHg, P < 0.00001). Granulocyte macrophage-colony stimulating factor failed to show a significant increase in anastomotic bursting pressure (95%CI: -20 to 21 mmHg, P = 0.97) vs controls in experimental chemotherapeutic models.

CONCLUSION: This systematic review identified potential therapeutic agents, but more studies are needed before concluding that any of these are useful for AL prophylaxis.

Is combined therapy more effective than growth hormone or hyperbaric oxygen alone in the healing of left ischemic and non-ischemic colonic anastomoses?

OBJECTIVE

Our aim was to investigate the effects of growth hormone (GH), hyperbaric oxygen and combined therapy on normal and ischemic colonic anastomoses in rats.

METHODS

Eighty male Wistar rats were divided into eight groups (n = 10). In the first four groups, non-ischemic colonic anastomosis was performed, whereas in the remaining four groups, ischemic colonic anastomosis was performed. In groups 5, 6, 7, and 8, colonic ischemia was established by ligating 2 cm of the mesocolon on either side of the anastomosis. The control groups (1 and 5) received no treatment. Hyperbaric oxygen therapy was initiated immediately after surgery and continued for 4 days in groups 3 and 4. Groups 2 and 6 received recombinant human growth hormone, whereas groups 4 and 8 received GH and hyperbaric oxygen treatment. Relaparotomy was performed on postoperative day 4, and a perianastomotic colon segment 2 cm in length was excised for the detection of biochemical and mechanical parameters of anastomotic healing and histopathological evaluation.

RESULTS

Combined treatment with hyperbaric oxygen and GH increased the mean bursting pressure values in all of the groups, and a statistically significant increase was noted in the ischemic groups compared to the controls (p<0.05). This improvement was more evident in the ischemic and normal groups treated with combined therapy. In addition, a histopathological evaluation of anastomotic neovascularization and collagen deposition showed significant differences among the groups.

CONCLUSIONS

Combined treatment with recombinant human growth hormone and hyperbaric oxygen resulted in a favorable therapeutic effect on the healing of ischemic colonic anastomoses.

Bone marrow stromal cells can cause subcutaneous fibroblasts to differentiate into osteocytes in a physically stable spatial microenvironment in rats

In this study, we investigated how rat bone marrow stromal cells (BMSCs) under a physically stable microenvironment influenced the subcutaneous fibroblasts. The model for this study involved setting up a space made up of a titanium mesh cage inserted into the subcutaneous region in rats and filled with a collagen matrix seeded with (1) BMSCs, (2) fibroblasts or (3) a combination of BMSCs and fibroblasts. Fibroblasts for transplantations were taken from enhanced green fluorescence protein (EGFP) transgenic "green rats" which enabled us to trace the fate of the cells in vivo. A series of X-ray computed tomographic (CT) images were taken of each implant over a period of 8 weeks, and the implants were then removed and examined histologically. As a result, while generated bone was observed in each case that included BMSCs (the BMSCs and combination group), there was no generated bone observed in the group using fibroblasts only. Interestingly, EGFP-positive osteocytes were observed in the generated bone of the combination group, indicating that the transplanted fibroblasts differentiated into osteocytes during the bone formation. Thus, we demonstrated that genuine intrinsic fibroblasts are able to become osteocytes as a result of the influence of BMSCs.

External coating of colonic anastomoses: a systematic review

PURPOSE

Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic anastomoses.

METHODS

CINAHL, EMBASE, and PubMed were searched up to September 2011 to identify studies evaluating external coating of colonic anastomoses.

RESULTS

Forty studies have evaluated 20 different coating materials, of which only fibrin sealant, omental pedicle graft, and hyaluronic acid/carboxymethylcellulose have been used in humans. Fibrin sealant has shown positive, however not significant, results. Omental pedicle graft can be used safely, yet without beneficial effects, whereas hyaluronic acid/carboxymethylcellulose should be avoided due to increased complications. The remaining coating materials have solely been evaluated in experimental animals with many contradictory and few positive results.

CONCLUSIONS

External coating of colonic anastomoses has yet failed to show convincing results. Randomized clinical trials and high-quality experimental studies are warranted to determine the role of fibrin sealant, omental pedicle graft, and other coating materials for prevention of colon anastomotic leakage.

Adipose-tissue-derived Stem Cells Enhance the Healing of Ischemic Colonic Anastomoses: An Experimental Study in Rats

Purpose

This experimental study verified the effect of adipose-tissue-derived stem cells (ASCs) on the healing of ischemic colonic anastomoses in rats.

Methods

ASCs were isolated from the subcutaneous fat tissue of rats and identified as mesenchymal stem cells by identification of different potentials. An animal model of colonic ischemic anastomosis was induced by modifying Nagahata's method. Sixty male Sprague-Dawley rats (10-week-old, 370 ± 50 g) were divided into two groups (n = 30 each): a control group in which the anastomosis was sutured in a single layer with 6-0 polypropylene without any treatment and an ASCtreated group (ASC group) in which the anastomosis was sutured as in the control group, but then ASCs were locally transplanted into the bowel wall around the anastomosis. The rats were sacrificed on postoperative day 7. Healing of the anastomoses was assessed by measuring loss of body weight, wound infection, anastomotic leakage, mortality, adhesion formation, ileus, anastomotic stricture, anastomotic bursting pressure, histopathological features, and microvascular density.

Results

No differences in wound infection, anastomotic leakage, or mortality between the two groups were observed. The ASC group had significantly more favorable anastomotic healing, including less body weight lost, less ileus, and fewer ulcers and strictures, than the control group. ASCs augmented bursting pressure and collagen deposition. The histopathological features were significantly more favorable in the ASC group, and microvascular density was significantly higher than it was in the control group.

Conclusion

Locally-transplanted ASCs enhanced healing of ischemic colonic anastomoses by increasing angiogenesis. ASCs could be a novel strategy for accelerating healing of colonic ischemic risk anastomoses.

Bone marrow mesenchymal cells: how do they contribute to tissue repair and are they really stem cells?

Adult stem cells typically generate the cell types of the tissue in which they reside, and thus the range of their differentiation is considered limited. Bone marrow mesenchymal stem cells (MSCs) are different from other somatic stem cells in that they differentiate not only into the same mesodermal-lineage such as bone, cartilage, and adipocytes but also into other lineages of ectodermal and endodermal cells. Thus, MSCs are a unique type of adult stem cells. In addition, MSCs home to damaged sites, differentiate into cells specific to the tissue and contribute to tissue repair. Therefore, application of MSCs in the treatment of various diseases, including liver dysfunction, myocardial infarction, and central nervous system repair, has been initiated. Because MSCs are generally harvested as adherent cells from bone marrow aspirates, however, they comprise heterogeneous cell populations and their wide-ranging differentiation ability and repair functions are not yet clear. Recent evidence suggests that a very small subpopulation of cells that assume a repair function with the ability to differentiate into trilineage cells resides among human MSCs and effective utilization of such cells is expected to improve the repair effect of MSCs. This review summarizes recent advances in the clarification of MSC properties and discusses future perspectives.

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.

VEGF-A and FGF gene therapy accelerate healing of ischemic colonic anastomoses (experimental study)

BACKGROUND

Reducing ischemic damage is one of the goals of surgery. The aim of this study was to apply human VEGF-A and FGF-2 DNA-mediated gene therapy in order to identify their effects in the healing of ischemic colon anastomoses and eliminating the negative effects of ischemia.

METHODS

Forty male Wistar albino rats weighing 250-280 g were divided into five equal groups (n = 8) as follows: group 1: control, ischemic left colonic anastomosis; group; 2: ischemic left colonic anastomosis with control plasmid delivery; group 3: ischemic left colonic anastomosis with VEGF plasmid delivery; group 4: ischemic left colonic anastomosis with FGF plasmid delivery; group 5: ischemic left colonic anastomosis with VEGF and FGF plasmid delivery. All rats were sacrificed on the 4th postoperative day. Anastomosis burst pressures were measured for mechanical examination of anastomosis. Tissue hydroxyprolin, VEGF and FGF levels were determined as biochemical parameters. Necrosis, epithelisation, inflammatory processes, fibroblastic activity, collagen deposition and neovascularisation at the anastomic site were studied.

RESULTS

VEGF, FGF and combined therapy significantly accelerated many of the histological parameters of healing, including fibroblast activation, collagen deposition, and angiogenesis, and augmented the levels of hydroxyproline and bursting pressure.

CONCLUSIONS

This is the first study to use gene therapy with growth factors for the healing of ischemic colonic anastomosis. This therapy can be effectively used in increasing ischemic anastomosis wound healing.