Functionalised biomaterials as synthetic extracellular matrices to promote vascularisation and healing of diabetic wounds.

Diabetic foot ulcers (DFU) are a type of chronic wound that constitute one of the most serious and debilitating complications associated with diabetes. The lack of clinically efficacious treatments to treat these recalcitrant wounds can lead to amputations for those worst affected. Biomaterial-based approaches offer great hope in this regard, as they provide a template for cell infiltration and tissue repair. However, there is an additional need to treat the underlying pathophysiology of DFUs, in particular insufficient vascularization of the wound which significantly hampers healing. Thus, the addition of pro-angiogenic moieties to biomaterials is a promising strategy to promote the healing of DFUs and other chronic wounds. In this review, we discuss the potential of biomaterials as treatments for DFU and the approaches that can be taken to functionalise these biomaterials such that they promote vascularisation and wound healing in pre-clinical models.

Extracellular matrix-inspired biomaterials for wound healing.

Diabetic foot ulcers (DFU) are a debilitating and life-threatening complication of Diabetes Mellitus. Ulceration develops from a combination of associated diabetic complications, including neuropathy, circulatory dysfunction, and repetitive trauma, and they affect approximately 19-34% of patients as a result. The severity and chronic nature of diabetic foot ulcers stems from the disruption to normal wound healing, as a result of the molecular mechanisms which underly diabetic pathophysiology. The current standard-of-care is clinically insufficient to promote healing for many DFU patients, resulting in a high frequency of recurrence and limb amputations. Biomaterial dressings, and in particular those derived from the extracellular matrix (ECM), have emerged as a promising approach for the treatment of DFU. By providing a template for cell infiltration and skin regeneration, ECM-derived biomaterials offer great hope as a treatment for DFU. A range of approaches exist for the development of ECM-derived biomaterials, including the use of purified ECM components, decellularisation and processing of donor/ animal tissues, or the use of in vitro-deposited ECM. This review discusses the development and assessment of ECM-derived biomaterials for the treatment of chronic wounds, as well as the mechanisms of action through which ECM-derived biomaterials stimulate wound healing.

"Flexures and bends of the large intestine: Current terminology and a suggestion to simplify it".

There are a number of inconsistencies in the description of the bends of the colon down to the anus. This is historically based on the fact that anatomists saw the colon in its position in the abdominal cavity down to the pelvis and thus from the "outside" and also described it in this way. This view is still useful in clinical practice today (e.g. for the abdominal surgeons). For the greater part of clinicians, however, the view has shifted due to modern endoscopy. This allows examiners to see the terminal section of the intestine and the colon from the "inside". To accommodate both "ways of looking" in terms of modern medicine, we have been guided by today's clinical needs, and here we attempt to reconcile these with the historically evolved anatomical terms to create a nomenclature that meets all the needs of students, anatomists and clinicians looking at the large intestine from the inside and outside. With this in mind, we propose to speak of colic flexures (right colic flexure = RCF = hepatic flexure, flexura coli sinistra; left colic flexure = LCF = splenic flexure, flexura coli dextra; descending-sigmoid flexure = DSF; sigmoid-rectum flexure = SRF) for the colon (colon). For the rectum (rectum), we suggest the term bend (superior, intermediate and inferior) when viewed in the frontal plane, the term curvature (sacral curvature; anorectal curvature = perineal curvature) when viewed in the sagittal plane.

Renal pathology in a mouse model of severe Spinal Muscular Atrophy is associated with downregulation of Glial Cell-Line Derived Neurotrophic Factor (GDNF).

Spinal muscular atrophy (SMA) occurs as a result of cell-ubiquitous depletion of the essential survival motor neuron (SMN) protein. Characteristic disease pathology is driven by a particular vulnerability of the ventral motor neurons of the spinal cord to decreased SMN. Perhaps not surprisingly, many other organ systems are also impacted by SMN depletion. The normal kidney expresses very high levels of SMN protein, equivalent to those found in the nervous system and liver, and levels are dramatically lowered by ~90-95% in mouse models of SMA. Taken together, these data suggest that renal pathology may be present in SMA. We have addressed this using an established mouse model of severe SMA. Nephron number, as assessed by gold standard stereological techniques, was significantly reduced. In addition, morphological assessment showed decreased renal vasculature, particularly of the glomerular capillary knot, dysregulation of nephrin and collagen IV, and ultrastructural changes in the trilaminar filtration layers of the nephron. To explore the molecular drivers underpinning this process, we correlated these findings with quantitative PCR measurements and protein analyses of glial cell-line-derived neurotrophic factor, a crucial factor in ureteric bud branching and subsequent nephron development. Glial cell-line-derived neurotrophic factor levels were significantly reduced at early stages of disease in SMA mice. Collectively, these findings reveal significant renal pathology in a mouse model of severe SMA, further reinforcing the need to develop and administer systemic therapies for this neuromuscular disease.

Soft-tissue landmarks for tibial baseplate rotational alignment in total knee arthroplasty: A cadaveric study.

The tip of the tibial tubercle (TTT) is used to assess tibial baseplate rotation in total knee arthroplasty (TKA); however, it can be difficult to palpate and visualize intraoperatively. Several more easily accessible soft-tissue structures have been proposed as intraoperative assessments, including the patellar tendon's medial border (MBPT) and the junction of the medial third of the patellar tendon (mt-PT). No studies have described the relationship between the TTT and these proposed landmarks. The aims of the study were to (1) determine the relationship of the soft-tissue landmarks to the TTT and (2) identify any sex differences in these measures. Measurements of the position of these soft-tissue landmarks relative to the TTT were made on 56 cadaveric knees (28 female) by two observers at the level of the standard tibial cut (10 mm distal to the lateral tibial plateau). The results obtained were compared by sex and side. On average, 50.7% (SD 6.79, range 33.1%-63.1%) of the patellar tendon footprint was medial to the TTT. There were no significant differences between the sexes or left and right lower limbs. However, there was large variability in the position of all the soft-tissue landmarks relative to the TTT. The results indicate that, on average, the patellar tendon footprint is evenly spread around the TTT. However, there is a large variability in the anatomical relationship between the soft-tissue landmarks and the TTT. Caution is advised if relying on these structures intraoperatively.

Neutralisation of SARS-CoV-2 by anatomical embalming solutions.

Teaching and learning anatomy by using human cadaveric specimens has been a foundation of medical and biomedical teaching for hundreds of years. Therefore, the majority of institutions that teach topographical anatomy rely on body donation programmes to provide specimens for both undergraduate and postgraduate teaching of gross anatomy. The COVID-19 pandemic has posed an unprecedented challenge to anatomy teaching because of the suspension of donor acceptance at most institutions. This was largely due to concerns about the potential transmissibility of the SARS-CoV-2 virus and the absence of data about the ability of embalming solutions to neutralise the virus. Twenty embalming solutions commonly used in institutions in the United Kingdom and Ireland were tested for their ability to neutralise SARS-CoV-2, using an established cytotoxicity assay. All embalming solutions tested neutralised SARS-CoV-2, with the majority of solutions being effective at high-working dilutions. These results suggest that successful embalming with the tested solutions can neutralise the SARS-CoV-2 virus, thereby facilitating the safe resumption of body donation programmes and cadaveric anatomy teaching.

COVID-19 and anatomy: Stimulus and initial response.

The outbreak of COVID-19, resulting from widespread transmission of the SARS-CoV-2 virus, represents one of the foremost current challenges to societies across the globe, with few areas of life remaining untouched. Here, we detail the immediate impact that COVID-19 has had on the teaching and practice of anatomy, providing specific examples of the varied responses from several UK, Irish and German universities and medical schools. Alongside significant issues for, and suspension of, body donation programmes, the widespread closure of university campuses has led to challenges in delivering anatomy education via online methods, a particular problem for a practical, experience-based subject such as anatomy. We discuss the short-term consequences of COVID-19 for body donation programmes and anatomical education, and highlight issues and challenges that will need to be addressed in the medium to long term in order to restore anatomy education and practice throughout the world.

The Use of Intermittent Pneumatic Compression in Orthopedic and Neurosurgical Postoperative Patients: A Systematic Review and Meta-analysis.

OBJECTIVE: The objective of this systematic review and meta-analysis was to carry out an up-to-date evaluation on the use of compression devices as deep vein thrombosis (DVT) prophylaxis methods in orthopedic and neurological patients. SUMMARY OF BACKGROUND DATA: There is an increased risk of DVT with surgery, particularly in patients who are not expected to mobilize soon after their procedures, such as orthopedic and neurosurgical patients. Compression devices are often employed for DVT prophylaxis in these patients. However, the true efficacy of these devices and the standardization of use with these devices are yet to be established. METHODS: Medline, CINAHL, Embase, Google Scholar, and the Cochrane library electronic databases were searched to identify randomized controlled trials and observational studies reporting on the use of compression devices for DVT prevention. RESULTS: Nine studies were included for review and meta-analysis. Use of an intermittent pneumatic compression device alone is neither superior nor inferior to chemoprophylaxis. CONCLUSIONS: In the absence of large randomized multicenter trials comparing the use of intermittent pneumatic compression or chemoprophylaxis alone to a combination of both treatments, the current evidence supports the use of a combined approach in high-risk surgical patients.

Changes in dermal matrix in the absence of Rac1 in keratinocytes.

Keratinocytes, in response to irritants, secrete pro-inflammatory mediators which recruit and activate immune and mesenchymal cells, including fibroblasts, to repair the skin. Fibroblasts respond by synthesising collagen and promoting the crosslinking extracellular matrix (ECM). We recently showed that the deletion of Rac1 in keratinocytes causes heightened inflammation due to aberrant crosstalk with immune cells. Indeed, the skin of these mice shows a higher inflammatory response to the induction of irritant contact dermatitis (ICD), and also even to treatment with a vehicle alone, compared with controls. As inflammation is intimately linked with fibrotic disease in the skin, this raised the question as to whether this deletion may also affect the deposition and arrangement of the dermal ECM. This study assessed the effects of Rac1 deletion in keratinocytes and of the heightened inflammatory status by induction of ICD on the tissue localisation and arrangements of dermal collagen. Qualitative analysis did not reveal evidence for the formation of pathologies in the dermis. However, quantitative analysis did reveal some perturbations in the dermal matrix, namely that only the combination of the lack of Rac1 and ICD affects the architectural organisation of the dermal collagen, and that a higher inflammatory state in the tissue (i.e. when Rac1 is deleted in the keratinocytes or ICD is induced in the skin, or a combination of both) influences the diameter of the collagen fibrils. It is proposed that this increase in the diameter of collagen fibrils due to inflammation may serve as pre-fibrotic marker enabling earlier determination of fibrosis and earlier treatment. This study has revealed previously unknown effects on the ECM due to the deletion of Rac1 in keratinocytes.

An appraisal of the computed axial tomographic appearance of the human mesentery based on mesenteric contiguity from the duodenojejunal flexure to the mesorectal level.

OBJECTIVE: The human mesentery is now regarded as contiguous from the duodenojejunal (DJ) to anorectal level. This interpretation prompts re-appraisal of computed tomography (CT) images of the mesentery. METHODS: A digital model and reference atlas of the mesentery were generated using the full-colour data set of the Visible Human Project (VHP). Seventy one normal abdominal CT images were examined to identify mesenteric regions. CT appearances were correlated with cadaveric and histological appearances at corresponding levels. RESULTS: Ascending, descending and sigmoid mesocolons were identifiable in 75%, 86% and 88% of the CTs, respectively. Flexural contiguity was evident in 66%, 68%, 71% and 80% for the ileocaecal, hepatic, splenic and rectosigmoid flexures, respectively. A posterior mesocolic boundary corresponding to the anterior renal fascia was evident in 40% and 54% of cases on the right and left, respectively. The anterior pararenal space (in front of the boundary) corresponded to the mesocolon. CONCLUSIONS: Using the VHP, a mesenteric digital model and reference atlas were developed. This enabled re-appraisal of CT images of the mesentery, in which contiguous flexural and non-flexural mesenteric regions were repeatedly identifiable. The anterior pararenal space corresponded to the mesocolon. KEY POINTS: The Visible Human Project (VHP) allows direct identification of mesenteric structures. Correlating CT and VHP allows identification of flexural and non-flexural mesenteric components. Radiologic appearance of intraperitoneal structures is assessed, starting from a mesenteric platform.

Protrusion-guided extracellular vesicles mediate CD30 trans-signalling in the microenvironment of Hodgkin's lymphoma.

Classical Hodgkin's lymphoma (cHL)-affected lymphoid tissue contains only a few malignant Hodgkin and Reed-Sternberg (HRS) cells, which are disseminated within a massive infiltrate of reactive cells. In particular, the innate immune infiltrate is deemed to support tumour growth by direct cell-cell interaction. Since they are rarely found in close proximity to the malignant cells in situ, we investigated whether cHL-derived extracellular vesicles might substitute for a direct cell-cell contact. We studied the crosstalk of the transmembrane proteins CD30 and CD30 ligand (CD30L) because they are selectively expressed on HRS and innate immune cells, respectively. Here, we showed that HRS cells released both the ectodomain as a soluble molecule (sCD30) and the entire receptor on the surface of extracellular vesicles. The vesicle diameter was 40-800 nm, as determined by cryo- and immune electron microscopy. In addition to CD30, typical extracellular vesicle markers were detected by mass spectrometry and flow cytometry, including tetraspanins, flotillins, heat shock proteins and adhesion molecules. In contrast to sCD30, vesicles caused a CD30-dependent release of interleukin-8 in CD30L(+) eosinophil-like EoL-1 cells and primary granulocytes from healthy donors, underscoring the functionality of CD30 on vesicles. In extracellular matrix (ECM)-embedded culture of HRS cells, a network of actin and tubulin-based protrusions guided CD30(+) vesicles into the micro-environment. This network targeted CD30(+) vesicles towards distant immune cells and caused a robust polarization of CD30L. Confocal laser scanning microscopy of 30 µm sections showed a CD30 vesicle-containing network also in cHL-affected lymphoid tissue of both mixed-cellularity and nodular sclerosing subtypes. This network might facilitate the communication between distant cell types in cHL tissue and allow a functional CD30-CD30L interaction in trans. The tubulin backbone of the network may provide a target for the therapy of cHL with antitubulin-based CD30 antibody constructs.

Mesenteric-Based Surgery Exploits Gastrointestinal, Peritoneal, Mesenteric and Fascial Continuity from Duodenojejunal Flexure to the Anorectal Junction--A Review.

INTRODUCTION: It is now well established that mesenteric-based colorectal surgery is associated with superior outcomes. Recent anatomic observations have demonstrated that the mesenteric organ is contiguous from the duodenojejunal to the anorectal junction. This led to similar observations in relation to associated peritoneum and fascia. The aim of this review was to demonstrate the relevance of the contiguity principle to resectional colorectal surgery. METHODS: All literature in relation to mesenteric anatomy was reviewed from 1873 to the present, without language restriction. RESULTS: Mesenteric-based surgery (i.e. complete mesocolic excision, total mesocolic and mesorectal excision) requires division of the peritoneal reflection (i.e. peritonotomy), and mesenteric mobilisation in the mesofascial plane. These are the fundamental technical elements of mesenterectomy. Mesenteric, peritoneal and fascial contiguity mean that in resectional surgery, these technical elements can be reproducibly applied at all levels from the origin at the superior mesenteric root, to the anorectal junction. CONCLUSIONS: The goals of complete mesocolic, total mesocolic and mesorectal excision can be universally achieved at any level from duodenojejunal flexure to anorectal junction, by adopting technical elements based on mesenteric, peritoneal and fascial contiguity.

The mesocolon: a histological and electron microscopic characterization of the mesenteric attachment of the colon prior to and after surgical mobilization.

BACKGROUND: Colonic mobilization requires separation of mesocolon from underlying fascia. Despite the surgical importance of planes formed by these structures, no study has formally characterized their microscopic features. The aim of this study was to determine the histological and electron microscopic appearance of mesocolon, fascia, and retroperitoneum, prior to and after colonic mobilization. METHODS: In 24 cadavers, samples were taken from right, transverse, descending, and sigmoid mesocolon. In 12 cadavers, specimens were stained with hematoxylin and eosin (3 sections) or Masson trichrome (3 sections). In the second 12 cadavers, lymphatic channels were identified by staining immunohistochemically for podoplanin. The ascending mesocolon was assessed with scanning electron microscopy. The above process was first conducted with the mesocolon in situ. The mesocolon was then surgically mobilized, and the process was repeated on remaining structures. RESULTS: The microscopic structure of mesocolon and associated fascia was consistent from ileocecal to mesorectal level. A surface mesothelium and underlying connective tissue were evident throughout. Fibrous septae separated adipocyte lobules. Where apposed to retroperitoneum, 2 mesothelial layers separated mesocolon and underlying retroperitoneum. A connective tissue layer occurred between these (ie, Toldt's fascia). Lymphatic channels were evident both in mesocolic connective tissue and Toldt's fascia. After surgical separation of mesocolon and fascia both remained contiguous, the fascia remained in situ and the retroperitoneum undisturbed. CONCLUSIONS: The findings demonstrate that the contiguous mesocolon and retroperitoneum are separated by mesothelial and connective tissue layers. These properties generate the surgical planes (ie, meso- and retrofascial planes) exploited in colonic and mesocolic mobilization.

RAC1 in keratinocytes regulates crosstalk to immune cells by Arp2/3-dependent control of STAT1.

Crosstalk between keratinocytes and immune cells is crucial for the immunological barrier function of the skin, and aberrant crosstalk contributes to inflammatory skin diseases. Using mice with a keratinocyte-restricted deletion of the RAC1 gene we found that RAC1 in keratinocytes plays an important role in modulating the interferon (IFN) response in skin. These RAC1 mutant mice showed increased sensitivity in an irritant contact dermatitis model, abnormal keratinocyte differentiation, and increased expression of immune response genes including the IFN signal transducer STAT1. Loss of RAC1 in keratinocytes decreased actin polymerization in vivo and in vitro and caused Arp2/3-dependent expression of STAT1, increased interferon sensitivity and upregulation of aberrant keratinocyte differentiation markers. This can be inhibited by the AP-1 inhibitor tanshinone IIA. Loss of RAC1 makes keratinocytes hypersensitive to inflammatory stimuli both in vitro and in vivo, suggesting a major role for RAC1 in regulating the crosstalk between the epidermis and the immune system.

Skin and diabetes mellitus: what do we know?

Diabetes mellitus (DM) is becoming increasingly prevalent worldwide. Although major complications of this condition involve kidney, retina and peripheral nerves, the skin of diabetic patients is also frequently injured. Hence, interest is mounting in the definition of the structural and molecular profile of non-complicated diabetic skin, i.e., before injuries occur. Most of the available knowledge in this area has been obtained relatively recently and, in part, derives from various diabetic animal models. These include both insulin-dependent and insulin-resistant models. Structural work in human diabetic skin has also been carried out by means of tissue samples or of non-invasive methods. Indications have indeed been found for molecular/structural changes in diabetic skin. However, the overall picture that emerges is heterogeneous, incomplete and often contradictory and many questions remain unanswered. This review aims to detail, as much as possible, the various pieces of current knowledge in a systematic and synoptic manner. This should aid the identification of areas in which key questions are still open and more research is needed. A comprehensive understanding of this field could help in determining molecular targets for the prevention and treatment of skin injuries in DM and markers for the monitoring of cutaneous and systemic aspects of the disease. Additionally, with the increasing development of non-invasive optics-based deep-tissue-imaging diagnostic technologies, precise knowledge of cutaneous texture and molecular structure becomes an important pre-requisite for the use of such methods in diabetic patients.

A detailed appraisal of mesocolic lymphangiology--an immunohistochemical and stereological analysis.

Inadequate resection of the adjoining mesentery is associated with adverse outcome for colon cancer. Disruption of the integrity of the mesenteric lymphatic package has been implicated in this, though not proven. Recent studies have determined mesenteric anatomy and histology and now provide an opportunity to determine accurately the distribution of lymphatic vessels. The aim of this study was to characterise the distribution of the lymphatic vessels (LV) within the small intestinal and colonic mesentery, and in Toldt's fascia, which lies between the mesocolon and underlying retroperitoneum. Mesenteric samples were harvested from 12 human cadavers. Samples were taken from the small bowel mesentery, ascending, transverse, descending mesocolon and from both apposed and non-apposed portions of the mesosigmoid. Serial sections were stained immunohistochemically with monoclonal antibody D2-40 (podoplanin), and Masson's Trichrome. Lymphatic vessel (LV) density and radius of diffusion were determined using a stereological approach. A lymphatic network was embedded within the mesenteric connective tissue lattice throughout each mesenteric region. LV were identifiable within the submesothelial connective tissue where they measured 10.2 ± 4.1 µm in diameter and had an average radius of diffusion of 174.72 ± 97.68 µm. Unexpectedly, LV were identified in Toldt's fascia, where they measured 4.3 ± 3.1 µm in diameter and had a radius of diffusion of 165.12 ± 66.26 µm. This is the first study systematically to determine and quantify the distribution of lymphatic vessels within the mesenteric organ and to demonstrate the presence of such vessels within Toldt's fascia. A rich lymphatic network occupies all levels of the mesenteric connective tissue lattice. Within the latter, they are found within 0.1 mm of peritonealised mesenteric surfaces and are separated by an average distance of 0.17 mm and may be particularly vulnerable during surgery.

The legal and ethical framework governing body donation in Europe - 2nd update on current practice.

BACKGROUND: In 2008, members of the TEPARG provided first insights into the legal and ethical framework governing body donation in Europe. In 2012, a first update followed. This paper is now the second update on this topic and tries to extend the available information to many more European countries. METHODS: For this second update, we have asked authors from all European countries to contribute their national perspectives. By this enquiry, we got many contributions compiled in this paper. When we did not get a personal contribution, one of us (EB) searched the internet for relevant information. RESULTS: Perspectives on the legal and ethical framework governing body donation in Europe. CONCLUSIONS: We still see that a clear and rigorous legal framework is still unavailable in several countries. We found national regulations in 18 out of 39 countries; two others have at least federal laws. Several countries accept not only donated bodies but also utilise unclaimed bodies. These findings can guide policymakers in reviewing and updating existing laws and regulations related to body donation and anatomical studies.

N-WASP is a novel regulator of hair-follicle cycling that controls antiproliferative TGF{beta} pathways.

N-WASP is a cytoplasmic molecule mediating Arp2/3 nucleated actin polymerization. Mice with a keratinocyte-specific deletion of the gene encoding N-WASP showed normal interfollicular epidermis, but delayed hair-follicle morphogenesis and abnormal hair-follicle cycling, associated with cyclic alopecia and prolonged catagen and telogen phases. The delayed anagen onset correlated with an increased expression of the cell-cycle inhibitor p21CIP, and increased activity of the TGFbeta pathway, a known inducer of p21CIP expression. Primary N-WASP-null keratinocytes showed reduced growth compared with control cells and enhanced expression of the gene encoding the cell-cycle inhibitor p15INK4B, a TGFbeta target gene. Inhibition of TGFbeta signaling blocked overexpression of p15INK4B and restored proliferation of N-WASP-deficient keratinocytes in vitro. However, induction of N-WASP gene deletion in vitro did not result in obvious changes in TGFbeta signaling or growth of keratinocytes, indicating that the in vivo environment is required for the phenotype development. These data identify the actin nucleation regulator N-WASP as a novel element of hair-cycle control that modulates the antiproliferative and pro-apoptotic TGFbeta pathway in keratinocytes in vivo and in vitro.

The role of basement membranes in cardiac biology and disease.

Basement membranes (BMs) are highly specialised extracellular matrix (ECM) structures that within the heart underlie endothelial cells (ECs) and surround cardiomyocytes and vascular smooth muscle cells. They generate a dynamic and structurally supportive environment throughout cardiac development and maturation by providing physical anchorage to the underlying interstitium, structural support to the tissue, and by influencing cell behaviour and signalling. While this provides a strong link between BM dysfunction and cardiac disease, the role of the BM in cardiac biology remains under-researched and our understanding regarding the mechanistic interplay between BM defects and their morphological and functional consequences remain important knowledge-gaps. In this review, we bring together emerging understanding of BM defects within the heart including in common cardiovascular pathologies such as contractile dysfunction and highlight some key questions that are now ready to be addressed.