Bladder Reconstruction with Human Amniotic Membrane in a Xenograft Rat Model: A Preclinical Study

The Regenerative Capacity of Tissue-Engineered Amniotic Membranes

Scaffolds can be introduced as a source of tissue in reconstructive surgery and can help to improve wound healing. Amniotic membranes (AMs) as scaffolds for tissue engineering have emerged as promising biomaterials for surgical reconstruction due to their regenerative capacity, biocompatibility, gradual degradability, and availability. They also promote fetal-like scarless healing and provide a bioactive matrix that stimulates cell adhesion, migration, and proliferation. The aim of this study was to create a tissue-engineered AM-based implant for the repair of vesicovaginal fistula (VVF), a defect between the bladder and vagina caused by prolonged obstructed labor. Layers of AMs (with or without cross-linking) and electrospun poly-4-hydroxybutyrate (P4HB) (a synthetic, degradable polymer) scaffold were joined together by fibrin glue to produce a multilayer scaffold. Human vaginal fibroblasts were seeded on the different constructs and cultured for 28 days. Cell proliferation, cell morphology, collagen deposition, and metabolism measured by matrix metalloproteinase (MMP) activity were evaluated. Vaginal fibroblasts proliferated and were metabolically active on the different constructs, producing a distributed layer of collagen and proMMP-2. Cell proliferation and the amount of produced collagen were similar across different groups, indicating that the different AM-based constructs support vaginal fibroblast function. Cell morphology and collagen images showed slightly better alignment and organization on the un-cross-linked constructs compared to the cross-linked constructs. It was concluded that the regenerative capacity of AM does not seem to be affected by mechanical reinforcement with cross-linking or the addition of P4HB and fibrin glue. An AM-based implant for surgical repair of internal organs requiring load-bearing functionality can be directly translated to other types of surgical reconstruction of internal organs.

The Effect of Multilayered Electrospun PLLA Nanofibers Coated with Human Amnion or Bladder ECM Proteins on Epithelialization and Smooth Muscle Regeneration in the Rabbit Bladder

Nanofibrous scaffolds have attracted much attention in bladder reconstruction approaches due to their excellent mechanical properties. In addition, their biological properties can be improved by combination with biological materials. Taking into account the advantages of nanofibrous scaffolds and decellularized extracellular matrix (dECM) in tissue engineering, scaffolds of poly-L-lactic acid (PLLA) coated with decellularized human amnion membrane (hAM) or sheep bladder (SB)-derived ECM proteins are developed (amECM-coated PLLA and sbECM-coated PLLA, respectively). The bladder regenerative potential of modified electrospun PLLA scaffolds is investigated in rabbits. The presence of ECM proteins is confirmed on the nanofibers' surface. Coating the surface of the PLLA nanofibers improves cell adhesion and proliferation. Histological and immunohistochemical evaluations show that rabbits subjected to cystoplasty with a multilayered PLLA scaffold show de novo formation and maturation of the multilayered urothelial layer. However, smooth muscle bundles (myosin heavy chain [MHC] and α-smooth muscle actin [α-SMA] positive) are detected only in ECM-coated PLLA groups. All groups show no evidence of a diverticulumor fistula in the urinary bladder. These results suggest that the biofunctionalization of electrospun PLLA nanofibers with ECM proteins can be a promising option for bladder tissue engineering. Furthermore, hAM can also replace animal-sourced ECM proteins in bladder tissue regeneration approaches.

Functional Recovery after the Application of Amniotic Tissues and Methylene Blue during Radical Prostatectomy-A Pilot Study

Amniotic tissues and methylene blue (MB) provide the ability for neuroregeneration, and MB enables intraoperative neurostaining. We first combined the techniques to explore a neuroprotective effect on early functional outcomes in a retrospective proof-of-concept trial of 14 patients undergoing radical prostatectomy (RP). The patients were followed up at a median of 13 months, and the continence and potency rates were reported. Early recovery of continence was found after three months. No effect on potency was detected. The findings indicate the feasibility of this tissue-engineering strategy, and justify prospective comparative studies.

Preparation of human amniotic membrane for transplantation in different application areas

The human amniotic membrane (hAM) is the inner layer of the placenta and plays protective and nutritional roles for the fetus during pregnancy. It contains multiple growth factors and proteins that mediate unique regenerative properties and enhance wound healing in tissue regeneration. Due to these characteristics hAM has been successfully utilized in ophthalmology for many decades. This material has also found application in a variety of additional therapeutic areas. Particularly noteworthy are the extraordinary effects in the healing of chronic wounds and in the treatment of burns. But hAM has also been used successfully in gynecology, oral medicine, and plastic surgery and as a scaffold for in vitro cell culture approaches. This review aims to summarize the different graft preparation, preservation and storage techniques that are used and to present advantages and disadvantages of these methods. It shows the characteristics of the hAM according to the processing and storage methods used. The paper provides an overview of the currently mainly used application areas and raises new application possibilities. In addition, further preparation types like extracts, homogenates, and the resulting treatment alternatives are described.

Application of amniotic membranes in reconstructive surgery of internal organs-A systematic review and meta-analysis

Amniotic membrane (AM) has great potential as a scaffold for tissue regeneration in reconstructive surgery. To date, no systematic review of the literature has been performed for the applications of AM in wound closure of internal organs. Therefore, in this systematic review and meta-analysis, we summarize the literature on the safety and efficacy of AM for the closure of internal organs. A systematic search was performed in MEDLINE-PubMed database and OVID Embase to retrieve human and controlled animal studies on wound closure of internal organs. The Cochrane Risk of Bias tool for randomized clinical trials and the SYRCLE risk of bias tool for animal studies were used. Meta-analyses (MAs) were conducted for controlled animal studies to assess efficacy of closure, mortality and complications in subjects who underwent surgical wound closure in internal organs with the application of AM. Sixty references containing 26 human experiments and 36 animal experiments were included. The MAs of the controlled animal studies showed comparable results with regard to closure, mortality and complications, and suggested improved mechanical strength and lower inflammation scores after AM application when compared to standard surgical closure techniques. This systematic review and MAs demonstrate that the application of AM to promote wound healing of internal organs appears to be safe, efficacious, and feasible.

Standardized reporting of amnion and amnion/chorion allograft data for wound care

Background

The favorable biological and mechanical properties of the most common components of the placenta, the amnion and chorion, have been explored for regenerative medical indications. The use of the combination of amnion and chorion has also become very popular. But, published data from placental tissues in their final, useable form is lacking. During treatment with membrane product, the tissue is usually sterile, intact and laid on a wound or treatment area. The factors available to the treatment area from the applied product need to be elucidated and presented in a relatable form. Current reporting for eluted growth factor results are typically expressed per milliliter, which is not informative with respect to the area of tissue covered by the actual membrane and may differ among techniques.

Methods

To address this inconsistency, amnion or amnion/chorion were isolated from human placentas and processed by a proprietary procedure. The final dry, sterilized product was evaluated for structural components and growth factor elution. Growth factors were quantified by multiplex panels and ELISAs and the values normalized to specific area and elution volume of finished product. This information allows extrapolation to all membrane sizes and affords cross‐study comparisons.

Results

Analysis of membrane supernatants show that dehydrated, sterilized amnion and amnion/chorion elute factors that are conducive to wound healing, which are available to recipient tissues. Importantly, these measurable factors eluted from dehydrated, sterilized membranes can be reported as a function of available factors per square centimeter of tissue.

Conclusions

The standardized characterization of dehydrated, sterilized amnion and amnion/chorion as delivered to recipient tissues permits understanding and comparison of the products across various graft sizes, types, and eluate volumes. Further, reporting this data as a function of cm² of dehydrated tissue allows extrapolation by independent scientists and clinicians.

Human Amniotic Membrane Enriched with Urinary Bladder Fibroblasts Promote the Re-Epithelization of Urothelial Injury

Culturing cells in three-dimensional systems that include extracellular matrix components and different cell types mimic the native tissue and as such provide much more representative results than conventional two-dimensional cell cultures. In order to develop biomimetic bladder tissue in vitro, we used human amniotic membrane (AM) extracellular matrix as a scaffold for bladder fibroblasts (BFs) and urothelial cells. Our aims were to evaluate the integration of BFs into the AM stroma, to assess the differentiation of the urothelium on BFs-enriched AM scaffolds, and to evaluate the AM as a urothelial wound dressing. First, to achieve the optimal integration of BFs into AM stroma, different intact and de- epithelialized AM (dAM) scaffolds were tested. BFs secreted matrix metalloproteinase (MMP)-1 and MMP-2 and integrated into the stroma of all types of AM scaffolds. Second, to establish urothelial tissue equivalent, urothelial cells were seeded on dAM scaffolds enriched with BFs. The BFs in the stroma of the AM scaffolds promoted (1) the proliferation of urothelial cells, (2) the attachment of urothelial cells on AM basal lamina with hemidesmosomes, and (3) development of multilayered urothelium with expressed uroplakins and well-developed cell junctions. Third, we established an ex vivo model of the injured bladder to evaluate the dAM as a wound dressing for urothelial full-thickness injury. dAM acted as a promising wound dressing since it enabled rapid re-epithelization of urothelial injury and integrated into the bladder tissue. Herein, the developed urothelial tissue equivalents enable further mechanistic studies of bladder epithelial–mesenchymal interactions, and they could be applied as biomimetic models for preclinical testing of newly developed drugs. Moreover, we could hypothesize that AM may be suitable as a dressing of the wound that occurs during transurethral resection of bladder tumor, since it could diminish the possibility of tumor recurrence, by promoting the rapid re-epithelization of the urothelium.

A Review on Modifications of Amniotic Membrane for Biomedical Applications

The amniotic membrane (AM) is the innermost layer of the fetal placenta, which surrounds and protects the fetus. Its unique structure, in addition to its physical and biological properties, makes it a useful substance in many applications related to regenerative medicine. The use of this fantastic substance with a century-old history has produced remarkable results in vivo, in vitro, and even in clinical studies. While the intact or preserved AM is widely used for these purposes, the addition of further modifications to AM can be considered as a relatively new subject in its applications. These modifications are applied to improve AM properties, ease of handling, and durability. Here, we will discuss the cases in which AM has undergone additional modifications besides the required processes for sterilization and preservation. In this article, we have categorized these modifications and discussed their applications and results.

The Cells and Extracellular Matrix of Human Amniotic Membrane Hinder the Growth and Invasive Potential of Bladder Urothelial Cancer Cells

Bladder cancer is one of the most common cancers among men in industrialized countries and on the global level incidence and mortality rates are increasing. In spite of progress in surgical treatment and chemotherapy, the prognosis remains poor for patients with muscle-invasive bladder cancer. Therefore, there is a great need for the development of novel therapeutic approaches. The human amniotic membrane (hAM) is a multi-layered membrane that comprises the innermost part of the placenta. It has unique properties that make it suitable for clinical use, such as the ability to promote wound healing and decrease scarring, low immunogenicity, and immunomodulatory, antimicrobial and anticancer properties. This study aimed to investigate the effect of (i) hAM-derived cells and (ii) hAM scaffolds on the growth dynamics, proliferation rate, and invasive potential of muscle-invasive bladder cancer T24 cells. Our results show that 24 and 48 h of co-culturing T24 cells with hAM-derived cells (at 1:1 and 1:4 ratios) diminished the proliferation rate of T24 cells. Furthermore, when seeded on hAM scaffolds, namely (1) epithelium of hAM (e-hAM), (2) basal lamina of hAM (denuded; d-hAM), and (3) stroma of hAM (s-hAM), the growth dynamic of T24 cells was altered and proliferation was reduced, even more so by the e-hAM scaffolds. Importantly, despite their muscle-invasive potential, the T24 cells did not disrupt the basal lamina of hAM scaffolds. Furthermore, we observed a decrease in the expression of epithelial-mesenchymal transition (EMT) markers N-cadherin, Snail and Slug in T24 cells grown on hAM scaffolds and individual T24 cells even expressed epithelial markers E-cadherin and occludin. Our study brings new knowledge on basic mechanisms of hAM affecting bladder carcinogenesis and the results serve as a good foundation for further research into the potential of hAM-derived cells and the hAM extracellular matrix to serve as a novel bladder cancer treatment.

An Evaluation of Wound Healing Efficacy of a Film Dressing Made from Polymer-integrated Amnion Membrane

A film dressing is an easy and common wound management, which is flexible to cover many types of superficial injuries. In a recent study, we developed a scaffold from poly (1,8-octanediolco-citrate) incorporated decellularized amnion membrane (DAM-POC). The DAM-POC scaffold was biocompatible and could enhance soft and hard tissue regeneration when applied to repair the cleft palate in rat. The efficacy of the DAM-POC scaffold in oral repair had led us to hypothesize that it could be employed extensively in the medical field as a wound dressing. This study aimed to investigate the feasibility and efficacy of the DAM-POC scaffold as a film dressing in accelerating wound healing when applied in multiple tissue injuries. Our results demonstrated that both the DAM and DAM-POC scaffolds were biocompatible and anti-adhesive without causing severe foreign body reactions when covering wounds in abdominal wall, back muscle, tibia bone, and liver. In addition, the DAM-POC scaffold was superior to the DAM scaffold in reducing inflammation, preventing fibrosis, and regenerating tissues. In conclusion, the DAM-POC scaffold might potentially be adopted as a film dressing in a wide range of therapeutic applications and healing situations to protect the damaged tissues from the external environment and prevent infections.

Amniotic Membrane Preparation Crucially Affects Its Broad-Spectrum Activity Against Uropathogenic Bacteria

Urinary tract infections are among the most common bacterial infections in humans. Moreover, they are highly recurrent and increasingly often resistant to antibiotics. The antimicrobial properties of the amniotic membrane (AM), the innermost layer of fetal membranes, have been briefly reported in the literature, however, the results of published studies are often inconsistent and unclear; moreover, its effect on uropathogenic bacteria has not yet been investigated. Further, there is no data in the literature about the effect of AM preparation and storage on its antimicrobial properties. To examine the impact of several preparation procedures on the antimicrobial properties of AM, we prepared patches and homogenates of fresh (fAM) and cryopreserved (cAM) human AM and tested them on 14 selected Gram-positive and Gram-negative uropathogenic bacteria. By employing novel antimicrobial efficiency assays we showed that fAM and cAM homogenates have broad-spectrum antimicrobial activity against all here tested uropathogenic bacteria, except for Serratia marcescens. Moreover, they had a potent effect also on the multiple-resistant clinical strains of uropathogenic Escherichia coli. Interestingly, the patches of fAM and cAM had no antimicrobial effect on any of the tested strains. We therefore prepared and stored AM patches according to the standard procedure for clinical use in ophthalmology, which includes the cryopreservation of antibiotic-treated AM, and performed antimicrobial efficiency assays. Our findings suggest that the ultrastructure of AM patches could enable the retention of added antibiotics. In addition, we also prepared gentamicin-resistant uropathogenic E. coli strains, which confirmed that the antimicrobial effect of antibiotic-treated AM patches can be attributed to the antibiotic alone. To summarize, here we describe novel protocols for preparation and storage of AM to ensure the preservation of its antimicrobial factors. Moreover, we describe the mechanism of AM retention of antibiotics, based on which the AM could potentially be used as a drug delivery vehicle in future clinically applicable approaches.

The biological mechanism involved in anticancer properties of amniotic membrane

The main role of amniotic membrane (AM), or amnion, is to protect the fetus from drying out and create an appropriate environment for its growth. AM is also a suitable candidate for the treatment of various diseases due to its unique characteristics. In recent years, a new line of research has focused on the anticancer properties of amnion and its potential use in cancer treatment. The in vitro and in vivo studies indicate the anti-proliferative and proapoptotic activities, as well as the angioregulatory and immunomodulatory properties of the amniotic membrane. However, the exact mechanism and molecular basis of these anticancer effects of AM are not fully elucidated. This paper presents an overview of the latest findings and knowledge about the anticancer effects of AM and its underlying molecular mechanisms, which is crucial for the application of amnion in cancer therapy.

Application of Dried Human Amnion Graft to Improve Post-Prostatectomy Incontinence and Potency: A Randomized Exploration Study Protocol

Introduction

Incontinence (up to 20%) and erectile dysfunction (up to 70%) occur frequently after radical prostatectomy (RP) in patients with localized prostate cancer. Human amniotic membrane (HAM) can improve tissue regeneration and functional outcome after RP owing to the growth factors and unique immune tolerance. Preliminary studies showed the potential value of HAM in the reconstruction of the urinary tract and nerve protection during RP.

Methods

A protocol is developed for a prospective, randomized, single-blind, single-surgeon, placebo-controlled exploration study of the efficacy and safety of dehydrated human amnion membrane placed around the neurovascular bundle (NVB) and vesicourethral anastomosis (VUA) during RP for the treatment of localized prostate cancer. Eligible for inclusion are patients with localized prostate cancer, requiring a surgical procedure and exclusion of preoperative incontinence and erectile dysfunction. The patients are randomized 1:1 to HAM vs. placebo and blinded during the study period. According to the T test with an alpha of 0.05 and a power of 80% and expecting a dropout of 20% of the patients, an adjusted sample size per arm of 164 patients is required.

Planned Outcomes

The primary outcome is a postoperative continence measured as 24-h pad test up to 12 months postoperatively. Secondary outcomes are potency, time of postoperative catheter removal, postoperative complications, and biochemical recurrence. The protocol for this randomized exploration study defines the conditions to assess the efficacy and safety of HAM application during RP in order to improve the postoperative functional outcome. This trial should pave the way for future studies of tissue engineering in an effort to reduce the morbidity of RP.

Trial Registration

Clinicaltrials.gov, identifier NCT03864939.

Human Amniotic Membrane and Amniotic Membrane-Derived Cells: How Far Are We from Their Use in Regenerative and Reconstructive Urology?

Human amniotic membrane (hAM) is the innermost layer of fetal membranes, which surrounds the developing fetus and forms the amniotic cavity. hAM and hAM-derived cells possess many properties that make them suitable for use in regenerative medicine, such as low immunogenicity, promotion of epithelization, anti-inflammatory properties, angiogenic and antiangiogenic properties, antifibrotic properties, antimicrobial properties, and anticancer properties. Many pathological conditions of the urinary tract lead to organ damage or complete loss of function. Consequently, the reconstruction or replacement of damaged organs is needed, which makes searching for new approaches in regenerative and reconstructive urology a necessity. The use of hAM for treating defects in kidneys, ureters, urinary bladder, and urethra was tested in vitro in cell cultures and in vivo in mice, rats, rabbits, cats, dogs, and also in humans. These studies confirmed the advantages and the potential of hAM for use in regenerative and reconstructive urology as stated above. However, they also pointed out a few concerns we have to take into consideration. These are (1) the lack of a standardized protocol in hAM preparation and storage, (2) the heterogeneity of hAM, and especially (3) low mechanical strength of hAM. Before any wider use of hAM for treating urological defects, the protocols for preparation and storage will need to be standardized, followed by more studies on larger animals and clinical trials, which will altogether extensively assess the potential of hAM use in urological patients.

Amniotic membrane as novel scaffold for human iPSC-derived cardiomyogenesis

Recent approaches of using decellularized organ matrices for cardiac tissue engineering prompted us to culture human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) on the human amniotic membrane (hAM). Since hAM has been used lately to patch diseased hearts in patients and has shown anti-inflammatory and anti-fibrotic benefits, it qualifies as a cardiac compatible and clinically relevant heart tissue scaffold. The aim of this study was to test the ability of the hAM to support attachment, differentiation, and maturation of hiPSC-derived CMs in vitro. hAMs were prepared from term placenta. An in-house generated hiPSC line was used for CM derivation. hiPSC-derived cardiac progenitors were cultured on the surface of cryopreserved hAMs and in the presence of cytokines promoting cardiac differentiation. CMs grown on hAM and popular basement membrane matrix (BMM) Matrigel™ were compared for the following aspects of cardiac development: the morphology of cardiomyocytes with respect to shape and cellular alignments, levels of cardiac-related gene transcript expression, functionality in terms of spontaneous calcium fluxes and mitochondrial densities and distributions. hAM is biocompatible with hiPSC-derived CMs. hAM increased cardiac transcription regulator and myofibril protein transcript expression, accelerated intracellular calcium transients, and enhanced cellular mitochondrial complexity of its cardiomyocytes in comparison to cardiomyocytes differentiated on Matrigel™. Our data suggests that hAM supports differentiation and improves cardiomyogenesis in comparison to Matrigel™. hAMs are natural, easily and largely available. The method of preparing hAM cardiac sheets described here is simple with potential for clinical transplantation. Graphical abstract A An outline of the differentiation protocol with stage-specific growth factors and culture media used. B Cell fates from pluripotent stem cells to cardiomyocytes during differentiation on the amniotic membrane. C-FPhotomicrographs of cells at various stages of differentiation. Scale bars represent 100 μm.

Application of amniotic membrane in reconstructive urology; the promising biomaterial worth further investigation

Introduction: In reconstructive urology, autologous tissues such as intestinal segments, skin, and oral mucosa are used. Due to their limitations, reconstructive urologists are waiting for a novel material, which would be suitable for urinary tract wall replacement. Human amniotic membrane (AM) is a naturally derived biomaterial with a capacity to support reepithelization and inhibit scar formation. AM has a potential to become a considerable asset for reconstructive urology, i.e., reconstruction of ureters, urinary bladder, and urethrae. Areas covered: This review aims to discuss the potential application of human AM in reconstructive urology. The environment for urinary tract healing is particularly unfavorable due to the presence of urine. Due to its fetal origin, the bioactivity of AM is orientated to induce intrinsic regeneration mechanisms and inhibit scarring. This review introduces the concept of applying human AM in reconstructive urology procedures to improve their outcomes and future tissue engineering based strategies. Expert opinion: Many fields of medicine that have accomplished translational research have proven the usefulness of AM in clinical practice. There is an urgent need for studies to be conducted on large animal models that might convincingly demonstrate the underestimated potential of AM to urologists around the world.

Use of an acellular collagen-elastin matrix to support bladder regeneration in a porcine model of peritoneocystoplasty

Introduction

Bladder reconstruction without using the intestine remains a challenge to this day despite the development of new biomaterials and cell cultures. Human bladder engineering is merely anecdotic, and mostly in vitro and animal studies have been conducted.

Material and methods

In our study using a porcine model, we performed a bladder augmentation using an autologous parietal peritoneum graft (peritoneocystoplasty) and determined whether the attachment of an acellular collagen-elastin matrix (Group 1) or lack of (Group 2) had better histologic and functional results. Thus far, peritoneocystoplasty has rarely been performed or combined with a biomaterial.

Results

After 6 weeks, we observed different degrees of retraction of the new bladder wall in both groups, although the retraction was lower and the histological analysis showed more signs of regeneration (neoangiogenesis and less fibrosis) in Group 1 than when compared with Group 2. No transitional cells were found in the new bladder wall in any of the groups, and no differences were observed in the functional test results.

Conclusions

Performing a peritoneocystoplasty is an easy and safe procedure. The data supports the benefit of an acellular collagen–elastin matrix to reinforce bladder regeneration. However, in our study we observed too much retraction of the new wall and the histologic results were not acceptable to consider it an appropriate cystoplasty technique.

Human amniotic membrane dressing for the treatment of an infected wound due to an entero-cutaneous fistula: Case report

INTRODUCTION

Infected wounds are difficult to treat and there are no standardized protocols.

PRESENTATION OF CASE

We report a case of infected postoperative wound and entero-cutaneous fistula in a 83 years-old woman. An innovative treatment protocol for Human amniotic membrane (HAM)-assisted dressing of infected wound as the Idea Stage following the IDEAL recommendations is presented. The development of amnion preparation and the involved treatment steps are described. No adverse events and no graft rejection have been detected.

DISCUSSION

Favorable results confirm the technical simplicity, safety and efficacy of this procedure. HAM has been shown to promote wound healing and to have antibacterial characteristics, which was supported by the presented case.

CONCLUSION

We are able to report a successful treatment of an infected wound caused by entero-cutaneous fistula with HAM dressing. Following the IDEAL recommendations, consecutive prospective cohort trials are justified.

Bladder augmentation in children: current problems and experimental strategies for reconstruction

Bladder augmentation is a demanding surgical procedure and exclusively offered for selected children and has only a small spectrum of indications. Paediatric bladder voiding dysfunction occurs either on a basis of neurological dysfunction caused by congenital neural tube defects or on a basis of rare congenital anatomic malformations. Neurogenic bladder dysfunction often responds well to a combination of specific drugs and/or intermittent self-catheterization. However, selected patients with spinal dysraphism and children with congenital malformations like bladder exstrophy and resulting small bladder capacity might require bladder augmentation. Ileocystoplasty is the preferred method of bladder augmentation to date. Because of the substantial long-and short-term morbidity of augmentation cystoplasty, recent studies have tried to incorporate new techniques and technologies, such as the use of biomaterials to overcome or reduce the adverse effects. In this regard, homografts and allografts have been implemented in bladder augmentation with varying results, but recent studies have shown promising data in terms of proliferation of urothelium and muscle cells by using biological silk grafts.

Novel approach to gastric mucosal defect repair using fresh amniotic membrane allograft in dogs (experimental study)

Background

Gastric mucosal defect could result from several causative factors including the use of nonsteroidal anti-inflammatory drugs, Helicobacter pylori infection, gastrointestinal and spinal cord diseases, and neoplasia. This study was performed to achieve a novel simple, inexpensive, and effective surgical technique for the repair of gastric mucosal defect.

Methods

Six adult male mongrel dogs were divided into two groups (three dogs each). In the control positive group (C + ve), dogs were subjected to surgical induction of gastric mucosal defect and then treated using traditional medicinal treatment for such a condition. In the amniotic membrane (AM) group, dogs were subjected to the same operation and then fresh AM allograft was applied. Clinical, endoscopic, biochemical (serum protein and lipid and pepsin activity in gastric juice), histopathological, and immunohistochemistry evaluations were performed.

Results

Regarding endoscopic examination, there was no sign of inflammatory reaction around the grafted area in the AM group compared to the C + ve group. The leukocytic infiltration in the gastric ulcer was well detected in the control group and was less observed in the AM group. In the AM group, the concentrations of both protein and lipid profiles were nearly the same as those in serum samples taken preoperatively at zero time, which indicated that the AM grafting acted the same as gastric mucosa. The re-epithelization of the gastric ulcer in the C + ve group was not yet detected at 21 days, while in the AM group it was well observed covering most of the gastric ulcer. AM accelerated the re-epithelization of the gastric ulcer. The fibrous connective tissue and the precursor of collagen (COL IA1) were poorly detected in the gastric ulcer with AM application.

Conclusion

Using fresh AM allograft for repairing gastric mucosal defect in dogs showed great impact as a novel method to achieve optimum reconstruction of the gastric mucosal architecture and restoration of pre-epithelial, epithelial, and post-epithelial normal gastric mucosal barriers.