Thiel-embalming technique: investigation of possible modification in embalming tissue as evaluation model for radiofrequency ablation

Anatomical Location of the Vesical Branches of the Inferior Hypogastric Plexus in Human Cadavers

We have demonstrated in canines that somatic nerve transfer to vesical branches of the inferior hypogastric plexus (IHP) can be used for bladder reinnervation after spinal root injury. Yet, the complex anatomy of the IHP hinders the clinical application of this repair strategy. Here, using human cadavers, we clarify the spatial relationships of the vesical branches of the IHP and nearby pelvic ganglia, with the ureteral orifice of the bladder. Forty-four pelvic regions were examined in 30 human cadavers. Gross post-mortem and intra-operative approaches (open anterior abdominal, manual laparoscopic, and robot-assisted) were used. Nerve branch distances and diameters were measured after thorough visual inspection and gentle dissection, so as to not distort tissue. The IHP had between 1 to 4 vesical branches (2.33 ± 0.72, mean ± SD) with average diameters of 0.51 ± 0.06 mm. Vesical branches from the IHP arose from a grossly visible pelvic ganglion in 93% of cases (confirmed histologically). The pelvic ganglion was typically located 7.11 ± 6.11 mm posterolateral to the ureteral orifice in 69% of specimens. With this in-depth characterization, vesical branches from the IHP can be safely located both posterolateral to the ureteral orifice and emanating from a more proximal ganglionic enlargement during surgical procedures.

Human Dermal Decellularized ECM Hydrogels as Scaffolds for 3D In Vitro Skin Aging Models

Biomaterials play an important role in the development of advancing three dimensional (3D) in vitro skin models, providing valuable insights for drug testing and tissue-specific modeling. Commercial materials, such as collagen, fibrin or alginate, have been widely used in skin modeling. However, they do not adequately represent the molecular complexity of skin components. On this regard, the development of novel biomaterials that represent the complexity of tissues is becoming more important in the design of advanced models. In this study, we have obtained aged human decellularized dermal extracellular matrix (dECM) hydrogels extracted from cadaveric human skin and demonstrated their potential as scaffold for advanced skin models. These dECM hydrogels effectively reproduce the complex fibrillar structure of other common scaffolds, exhibiting similar mechanical properties, while preserving the molecular composition of the native dermis. It is worth noting that fibroblasts embedded within human dECM hydrogels exhibit a behavior more representative of natural skin compared to commercial collagen hydrogels, where uncontrolled cell proliferation leads to material shrinkage. The described human dECM hydrogel is able to be used as scaffold for dermal fibroblasts in a skin aging-on-a-chip model. These results demonstrate that dECM hydrogels preserve essential components of the native human dermis making them a suitable option for the development of 3D skin aging models that accurately represent the cellular microenvironment, improving existing in vitro skin models and allowing for more reliable results in dermatopathological studies.

Characterization of the layer, direction and time-dependent mechanical behaviour of the human oesophagus and the effects of formalin preservation

The mechanical characterization of the oesophagus is essential for applications such as medical device design, surgical simulations and tissue engineering, as well as for investigating the organ's pathophysiology. However, the material response of the oesophagus has not been established ex vivo in regard to the more complex aspects of its mechanical behaviour using fresh, human tissue: as of yet, in the literature, only the hyperelastic response of the intact wall has been studied. Therefore, in this study, the layer-dependent, anisotropic, visco-hyperelastic behaviour of the human oesophagus was investigated through various mechanical tests. For this, cyclic tests, with increasing stretch levels, were conducted on the layers of the human oesophagus in the longitudinal and circumferential directions and at two different strain rates. Additionally, stress-relaxation tests on the oesophageal layers were carried out in both directions. Overall, the results show discrete properties in each layer and direction, highlighting the importance of treating the oesophagus as a multi-layered composite material with direction-dependent behaviour. Previously, the authors conducted layer-dependent cyclic experimentation on formalin-embalmed human oesophagi. A comparison between the fresh and embalmed tissue response was carried out and revealed surprising similarities in terms of anisotropy, strain-rate dependency, stress-softening and hysteresis, with the main difference between the two preservation states being the magnitude of these properties. As formalin fixation is known to notably affect the formation of cross-links between the collagen of biological materials, the differences may reveal the influence of cross-links on the mechanical behaviour of soft tissues.

Undergraduate medical student perceptions and learning outcomes related to anatomy training using Thiel- and ethanol-glycerin-embalmed tissues

Anatomical dissection is known to serve as an integral tool in teaching gross anatomy, including postgraduate training. A variety of embalming techniques exist, resulting in different haptic and optical tissue properties. This study aimed to objectify learning outcomes and medical student perceptions related to the use of two widely used embalming techniques, namely Thiel and ethanol-glycerin embalming. Between 2020 and 2022, first- and second-year medical students enrolled in the course on topographic anatomy participated in this study. Objective structured practical examinations were carried out for the head, neck, thorax, abdomen, pelvis, and extremity regions following regional dissection just before the oral examinations began. Six to ten numbered tags were marked in prosections of each region in Thiel- and ethanol-glycerin-embalmed specimens. Following the examinations, the students were surveyed regarding the suitability of the two embalming techniques with respect to preservation, colorfastness, tissue pliability, and the suitability in preparing for their anatomy examinations. Consistently higher scores were achieved for the thoracic and abdominal regions in ethanol-glycerin-embalmed specimens when compared to Thiel. No benefit was found for Thiel-embalmed upper or lower extremities. Tissues embalmed with ethanol-glycerin were rated higher for preservation and suitability to achieve the learning objectives, tissue pliability was rated higher for Thiel-embalmed tissues. Ethanol-glycerin embalming appears to offer certain advantages for undergraduate students in recognizing visceral structures, which may align with students' ideas on tissue suitability for their learning. Consequently, the benefits reported for Thiel embalming for postgraduate study unlikely reflect its suitability for novices.

Use of Thiel-embalmed cadavers in urology training and their ability to retain real-life anatomy: a systematic review

BACKGROUND

Thiel-embalmed cadavers (TeCs) have been proposed as an alternative and probably safer method of surgical training, compared to formalin-embalmed cadavers. We aimed to perform a systematic review on the use of TeCs in urology training and their ability to represent real-life anatomy.

METHODS

PubMed, SCOPUS and Cochrane databases were searched for articles with purpose to explore the use of TeCs in urology training, without date restrictions, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From each paper, we evaluated the type of procedure, the number of participants, the type of study, the educational outcomes and their level, according to Kirkpatrick hierarchy.

RESULTS

Of the 225 records initially retrieved, eight articles were eventually included. All studies evaluated participants' perceptions about the procedure. Overall, urology trainees and specialists have positively commented on the educational value of TeCs, which have been also found able to adequately mimic real-life conditions. In all the eight studies, trainees stated that tissue quality of TeCs was adequately realistic and considered TeCs as a useful surgical training tool.

CONCLUSION

Although the use of TeCs in urology training has so far been limited, their value as a surgical training tool has been positively perceived. These outcomes suggest that TeCs may also enhance urology trainees' surgical skills and may encourage their implementation as a simulation tool in urology training.

Innovative Cadaver Preservation Techniques: a Systematic Review

Cadaveric dissection is a unique and unrivalled educational tool that allows students in medicine and associated life sciences to explore spatial three-dimensional anatomy, principles of structure and related function, and anatomical variations, including pathological alterations. Human tissue dissection enables researchers to comprehend the variety that exists in life that cannot be appreciated through the literature or artificial specimens. Using cadavers is the best way to simulate surgical and anatomical teaching. A cadaver has been shown to imitate surgical and anatomical training better than any other existing method. By the use of soft embalming approaches, cadavers have become more realistic and training-friendly. The main aim of this review is to describe various innovative and recent cadaver preservation techniques in detail, which can help anatomists to modify the techniques in their institute for gross anatomy teaching and surgical training or workshops to get a lifelike cadaver.

30 years of Thiel embalming - A systematic review on its utility in medical research

In 1992, Walter Thiel described and embalming method that rendered 'lifelike' tissues. Over the last 30 years, the Thiel method has been introduced worldwide for medical training and scientific purposes. This review examines research which can be linked to the use of Thiel embalming. A systematic review was performed to identify articles published in the following categories: research content, disciplines involved, sources and quantities of tissues deployed, and changes in research scope related to changes in the chemical composition of Thiel embalming. 424 publications were included. A number of adaptations to the original Thiel protocol were found, aiming to provide suitable tissue-substitutes in the development of emerging medical technologies or procedures. Musculoskeletal surgery, anesthesia and intensive care were the most common disciplines that used Thiel embalmed tissues for research. Anatomy and biomechanics played a lesser role. An increase over time was observed in research outputs related to the Thiel method, while the number of specimens used per study decreased. The main centers using Thiel embalming were in Graz, Dundee, Sapporo, Bern, Zurich and Ghent, which jointly accounted for more than 54% of all research conducted using this method. Following three decades of use, the Thiel method has evolved into being a well-established embalming technique for research purposes. Its future is challenged by the demanding requirements on both technical facilities and personnel, limitations of certain chemicals for use as fixatives, costs, and questions as to how 'lifelike' the embalmed-tissues are from an objective standpoint, all of which warrants future investigations. This article is protected by copyright. All rights reserved.

Cadaveric Models for Renal Transplant Surgery Education: a Comprehensive Review

PURPOSE OF REVIEW

To evaluate the utility of cadaveric models for kidney transplant (KT) surgery training.

RECENT FINDINGS

Medline® and PubMed® databases were searched for English and Spanish language articles published describing different learning models used in KT formation. We evaluated the use of cadavers preserved by Thiel's embalming method (TEM) as KT simulation models. Students were divided in groups of 4 people: four trainees mentored by an expert in KT surgery. Among the trainees were surgical residents and low-experience surgeons. A total of 39 TEM preserved bodies were used, of which 75 viable renal grafts were obtained. In each cadaver, two complete transplantation processes were performed, each consisting of en bloc nephrectomy with the trunk of aorta and inferior vena cava, bench surgery and perfusion with saline of the organ, and KT surgery. As with any surgical procedure, learning KT surgery is a stepwise process that requires years of dedication. The models available for the surgical simulation of KT surgery allow to practice and achieve dexterity in performing the procedure in a safe and reproducible way. Training on TEM-preserved corpses offers a highly realistic model for the surgical simulation of KT surgery.