Rabbit as an animal model for the study of biological grafts in pelvic floor dysfunctions

The use of animal models in preclinical investigations for the development of a surgical mesh for pelvic organ prolapse

INTRODUCTION AND HYPOTHESIS

Polypropylene (PP) mesh for the treatment of pelvic organ prolapse (POP) has raised substantial concerns over long-term complications, leading to its ban in multiple countries. In response, emerging materials are being explored as alternatives for prolapse surgery. Preclinical animal models have historically played a pivotal role in validating medical devices, prior to clinical trials. Successful translation of these materials necessitates the identification of suitable animal models that replicate the female human pelvis and its biomechanical properties. Preclinical in vivo testing assesses the safety of surgical mesh and treatment efficacy in preventing POP recurrence.

METHODS

The research critically reviews animal models used for preclinical pelvic mesh testing over the last decade and proposes a promising model for future preclinical studies.

RESULTS

Rats were the most common mammal used for toxicity and biocompatibility investigations through abdominal implantation. Although non-human primates serve as a gold standard for efficacy testing, ethical considerations limit their use owing to their close biological and cognitive resemblance to humans. Consequently, sheep were the most preferred large animal model owing to their reproductive system similarities and propensity for spontaneous POP following parity.

CONCLUSION

The study contributes valuable insights into the selection of appropriate animal models for preclinical pelvic mesh testing, offering guidance that is crucial for enhancing the safety and efficacy of novel surgical interventions in the treatment of POP.

Addressing the need for preclinical study of penile prosthesis infection: a new animal model and narrative review

Background and Objective

Erectile dysfunction (ED) is a common condition in men, and many patients refractory to conservative treatment may undergo penile prostheses (PPs) placement. The primary concern following PP implantation is device infection. Although antibiotic and hydrophilic coatings have reduced the incidence of inflatable PP (IPP) infections, there remains room for improvement. Optimization of PP outcomes requires a practical in vivo model to better understand mechanisms of infection and to test new infection control strategies. We aimed to describe a new rabbit model which contains a functional IPP and review previously reported animal PP models.

Methods

An IPP was placed into rabbit flanks and cycled for functionality testing. Rabbits were evaluated for signs of pain and distress over 14 days. Separately, narrative review methodology was utilized to search the PubMed and Scopus databases for all publications through March 21, 2023, which studied PP within an in vivo setting. Three independent reviewers ultimately selected 12 papers from 1992-2021 for inclusion.

Key Content and Findings

Several animal studies highlighted the initial functionality or feasibility of devices for ED before their introduction in the clinical setting. There are several subsequent studies aimed at optimizing the type of antibiotic use or coating material using segments of PP material in an in vivo setting. However, the literature lacks a contemporary animal model containing a functional IPP. Our novel rabbit model offers a safe, practical way to implant a functioning IPP and investigate new perioperative infection prevention and treatment strategies before trials in the clinical setting.

Conclusions

Animal models have played a key role in testing medical devices, including PPs, prior to their clinical introduction. Our review uncovered no modern animal studies involving placement of a functional PP. A new animal model can facilitate study of evolving microorganism profiles, novel methods to enhance antibiotic delivery, and proposed treatment options.

Development of a full-thickness acellular dermal graft from human skin: Case report of first patient rotator cuff patch augmentation repair

The processing and initial testing of a new human tissue preparation is described. Full-thickness Acellular Dermal Matrix (ftADM) is the extracellular matrix (ECM) obtained by decellularization of full-thickness human skin from cadaveric donors. The safety, stability and usability of the graft are discussed with respect to the results of the residual cellular content, maintenance of ECM components, and biomechanical properties. Quantitative and qualitative analysis of the ECM demonstrated the absence of cell debris, while the native structure of human dermis was maintained. Biomechanical testing showed stiffness values comparable to other commercial products used for tendon reinforcement, suggesting that our ftADM could be successfully used not only in soft tissue regeneration surgeries, but also in tendon reinforcement. First case of ftADM in rotator cuff augmentation is described. Technical management of the patch during surgery and clinical outcomes are discussed.

Comparison of a human acellular dermal matrix and a polypropylene mesh for pelvic floor reconstruction: a randomized trial study in a rabbit model

Non-absorbable polypropylene (PP) meshes have been widely used in surgical reconstruction of the pelvic floor disorders. However, they are associated with serious complications. Human acellular dermal matrices (hADM) have demonstrated safety and efficacy in reconstructive medicine, but their suitability and efficacy at vaginal level is not known. This study compares the biological performance of PP mesh and a newly developed hADM. 20 rabbits were randomized to receive the hADM graft or the PP mesh. Grafts were surgically implanted in the abdominal wall and vagina. After 180 days, grafts were explanted and evaluated. The vaginal mesh extrusion rate was higher in the PP group (33% vs. 0%, p = 0.015). Full integration of the vaginal grafts was more frequent in the hADM group, where 35% of the grafts were difficult to recognize. In the PP group, the vaginal mesh was identified in 100% of the animals (p = 0.014). In PP group, the infiltrates had a focal distribution and were mostly located in the internal part of the epithelium, while in the hADM group, the infiltrates had a diffuse distribution. Additionally, the hADM group also presented more B-lymphocytes and less T-lymphocytes. Biomechanical analysis showed that hADM had lower resistance to stress. Moreover, PP mesh stiffness and elasticity were higher. Then, hADM is associated with fewer clinical complications, as well as better tissue integration. However, it shows greater incorporation into the surrounding native tissue, especially in the vaginal location, undergoing a reduction in its biomechanical properties 6 months after implantation.

Fabrication and biological evaluation of three-dimensional (3D) Mg substituted bi-phasic calcium phosphate porous scaffolds for hard tissue engineering

This work reports on the fabrication of three-dimensional (3D) magnesium substituted bi-phasic calcium phosphate (Mg-BCP) scaffolds by gel-casting, their structural and physico-chemical characterization, and on the assessment of their in vitro and in vivo performances. The crystalline phase assemblage, chemical functional groups and porous morphology features of the scaffolds were evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FE-SEM), respectively. The sintered scaffolds revealed an interconnected porosity with pore sizes ranging from 4.3 to 7.28 μm. The scaffolds exhibited good biomineralization activity upon immersion in simulated body fluid (SBF), while an in vitro study using MG-63 cell line cultures confirmed their improved biocompatibility, cell proliferation and bioactivity. Bone grafting of 3D scaffolds was performed in non-load bearing bone defects surgically created in tibia of rabbits, used as animal model. Histological and radiological observations indicated the successful restoration of bone defects. The overall results confirmed the suitability of the scaffolds to be further tested as synthetic bone grafts in bone regeneration surgeries and in bone tissue engineering applications.

Human Acellular Dermal Matrix in Reconstructive Surgery-A Review

Reconstructive surgery often confronts large tissue defects. This creates a need to look for materials that are immunogenic but offer the possibility of tissue filling. ADM-acellular dermal matrix-is a biological collagen matrix without immunogenicity, which is more commonly used in surgical treatment. Reconstructive surgery is still searching for various biocompatible materials that can be widely used in surgery. The available materials have their advantages and disadvantages. This paper is a literature review on the use of human acellular dermal matrix (ADM) in reconstructive surgery (surgical oncology, plastic and reconstructive surgery, and gynecologic reconstructive surgery). ADM appears to be a material of increasing use in various fields of surgery, and thus, further research in this area is required.

Application of Acellular Dermal Matrix in Gynaecology—A Current Review

The aim of our study is to draw attention to the multitude of applications of acellular dermal matrix (ADM) in the surgical treatment of urogynaecological disorders, such as reduction in the reproductive organs, and in reconstructive gynaecology. Despite the existence of numerous operational methods and materials, the effectiveness of transvaginal operation is still insufficient. Native tissue operations are often not durable enough, while operations with synthetic materials have numerous side effects, such as infections, hematomas, vaginal erosion, or dyspareunia. Hence, the search continues for a different material with a better efficacy and safety profile than those previously mentioned. It seems that ADM can meet these requirements and be a useful material for urogynaecological surgery. Key words related to the usage of ADM in gynaecological reconstructive surgery were used to search relevant databases (NCBI MedLine, Clinical Key, Clinicaltrials.gov). This manuscript is based on 43 literature sources, 28 (65.11%) of which were released after 2016. Older sources are cited for the purpose of presenting basic science, or other important issues related to the manuscript. ADM seems to be an ideal material for urogynaecological and reconstructive surgery. It has high durability, and thus high effectiveness. Moreover, it does not have the side effects typical for synthetic materials. There are no reports of material rejection, erosion or dyspareunia directly related to the presence of the mesh. Due to the difficulties in obtaining ADM and the need to perform additional tests, this material is not common in routine clinical practice. Therefore, the number of cases and the size of the research groups are insufficient to clearly define the potential of mesh from biological tissue. However, the results are so promising that it is worth considering a wider introduction to the use of this material. Our hope is that increasing clinicians’ awareness of this topic will lead to more studies comparing methods using native tissues or synthetic materials and those using ADM.