Chemical imaging and assessment of cadmium distribution in the human body.

The scientific interest in cadmium (Cd) as a human health damaging agent has significantly increased over the past decades. However, particularly the histological distribution of Cd in human tissues is still scarcely defined. Using inductively coupled plasma-mass spectrometry (ICP-MS), we determined the concentration of Cd in 40 different human tissues of four body donors and provided spatial information by elemental imaging on the microscopic distribution of Cd in 8 selected tissues by laser ablation (LA)-ICP-MS. ICP-MS results show that Cd concentrations differ by a factor of 20 000 between different tissues. Apart from the well know deposits in kidney, bone, and liver, our study provides evidence that muscle and adipose tissue are underestimated Cd pools. For the first time, we present spatially resolved Cd distributions in a broad panel of human soft tissues. The defined histological structures are mirrored by sharp cut differences in Cd concentrations between neighboring tissue types, particularly in the rectum, testis, and kidneys. The spatial resolution of the Cd distribution at microscopic level visualized intratissue hot spots of Cd accumulation and is suggested as a powerful tool to elucidate metal based toxicity at histological level.

Visualization of the Membranous Labyrinth and Nerve Fiber Pathways in Human and Animal Inner Ears Using MicroCT Imaging.

Design and implantation of bionic implants for restoring impaired hair cell function relies on accurate knowledge about the microanatomy and nerve fiber pathways of the human inner ear and its variation. Non-destructive isotropic imaging of soft tissues of the inner ear with lab-based microscopic X-ray computed tomography (microCT) offers high resolution but requires contrast enhancement using compounds with high X-ray attenuation. We evaluated different contrast enhancement techniques in mice, cat, and human temporal bones to differentially visualize the membranous labyrinth, sensory epithelia, and their innervating nerves together with the facial nerve and middle ear. Lugol's iodine potassium iodine (I2KI) gave high soft tissue contrast in ossified specimens but failed to provide unambiguous identification of smaller nerve fiber bundles inside small bony canals. Fixation or post-fixation with osmium tetroxide followed by decalcification in EDTA provided superior contrast for nerve fibers and membranous structures. We processed 50 human temporal bones and acquired microCT scans with 15 µm voxel size. Subsequently we segmented sensorineural structures and the endolymphatic compartment for 3D representations to serve for morphometric variation analysis. We tested higher resolution image acquisition down to 3.0 µm voxel size in human and 0.5 µm in mice, which provided a unique level of detail and enabled us to visualize single neurons and hair cells in the mouse inner ear, which could offer an alternative quantitative analysis of cell numbers in smaller animals. Bigger ossified human temporal bones comprising the middle ear and mastoid bone can be contrasted with I2KI and imaged in toto at 25 µm voxel size. These data are suitable for surgical planning for electrode prototype placements. A preliminary assessment of geometric changes through tissue processing resulted in 1.6% volume increase caused during decalcification by EDTA and 0.5% volume increase caused by partial dehydration to 70% ethanol, which proved to be the best mounting medium for microCT image acquisition.

Analysis of Vestibular Labyrinthine Geometry and Variation in the Human Temporal Bone.

Stable posture and body movement in humans is dictated by the precise functioning of the ampulla organs in the semi-circular canals. Statistical analysis of the interrelationship between bony and membranous compartments within the semi-circular canals is dependent on the visualization of soft tissue structures. Thirty-one human inner ears were prepared, post-fixed with osmium tetroxide and decalcified for soft tissue contrast enhancement. High resolution X-ray microtomography images at 15 µm voxel-size were manually segmented. This data served as templates for centerline generation and cross-sectional area extraction. Our estimates demonstrate the variability of individual specimens from averaged centerlines of both bony and membranous labyrinth. Centerline lengths and cross-sectional areas along these lines were identified from segmented data. Using centerlines weighted by the inverse squares of the cross-sectional areas, plane angles could be quantified. The fit planes indicate that the bony labyrinth resembles a Cartesian coordinate system more closely than the membranous labyrinth. A widening in the membranous labyrinth of the lateral semi-circular canal was observed in some of the specimens. Likewise, the cross-sectional areas in the perilymphatic spaces of the lateral canal differed from the other canals. For the first time we could precisely describe the geometry of the human membranous labyrinth based on a large sample size. Awareness of the variations in the canal geometry of the membranous and bony labyrinth would be a helpful reference in designing electrodes for future vestibular prosthesis and simulating fluid dynamics more precisely.

Critical Ischemia Times and the Effect of Novel Preservation Solutions HTK-N and TiProtec on Tissues of a Vascularized Tissue Isograft.

BACKGROUND: We herein investigate critical ischemia times and the effect of novel preservation solutions such as new histidine-tryptophan-ketoglutarate (HTK-N) and TiProtec on the individual tissues of a rat limb isograft. METHODS: Orthotopic hind-limb transplantations were performed in male Lewis rats after 2 hours, 6 hours, or 10 hours of cold ischemia (CI). Limbs were flushed and stored in HTK-N, TiProtec, HTK, or saline solution. Muscle, nerve, vessel, skin, and bone samples were procured on day 10 for histology, immunohistochemistry, confocal and electron microscopy, and quantitative real-time polymerase chain reaction analysis. RESULTS: Histomorphology of the muscle showed a mainly perivascular inflammatory infiltrate, fibrotic degeneration, and neovascularization after 6 hours and 10 hours of CI. However, centrally aligned nuclei observed in muscle fibers suggest for muscle regeneration in these samples. In addition to Wallerian degeneration, nerve injury was significantly aggravated (P = 0.032) after prolonged CI. Proinflammatory and regulatory cytokines were most significantly upregulated after 2-hour CI. Our data suggest no superiority of novel perfusates HTK-N and TiProtec in terms of tissue preservation, compared with HTK and saline. CONCLUSIONS: Limiting CI time for less than 6 hours is the most significant factor to reduce tissue damage in vascularized tissue transplantation. Signs of muscle regeneration give rise that ischemic muscle damage in limb transplantation might be reversible to a certain extent.

The nonrecurrent laryngeal nerve: A clinical anatomic mapping with regard to intraoperative neuromonitoring.

BACKGROUND: We investigated the nonrecurrent inferior laryngeal nerve (nrILN), an important variant in the course of the inferior laryngeal nerve (ILN; 0.5-6.0%). Its importance was demonstrated in a clinical case as well as in cadaver specimens, and the pattern was identified with intraoperative neuromonitoring (IONM). METHODS: The ILN and the presence of an nrILN were investigated in 36 formaldehyde-embalmed specimens. Our anatomic findings showed differences in the anatomic course of the ILN and thus produced possible explanations for different IONM signals that would correlate with differences in the anatomic course of the ILN. Preoperative ultrasonographic evaluation of the brachiocephalic trunk and the recurrent laryngeal nerve were used for the exclusion or identification of an nrILN, respectively. RESULTS: We found 2 nrILNs (ascending, horizontal; 6%) in the anatomic specimens. These 2 specimens each showed an aberrant right subclavian artery (lusorial artery) and were, therefore, associated with the absence of a brachiocephalic trunk. The intraoperative case displayed a descending nrILN. Signals derived from the vagus nerve were positive if derived proximal to and negative if derived distal to the branching of an nrILN. By ultrasonographic identification of a normal brachiocephalic trunk, an nrILN could be excluded. CONCLUSION: Surgeons need a working knowledge about nrILNs to avoid recurrent nerve palsy and should be familiar with all the possible course variations in the ILN when IONM signals are absent with vagal stimulation. Moreover, endocrine surgeons need to be able to interpret correctly negative as well as positive signals. Preoperative ultrasonography should ideally be performed, because the presence of a normal brachiocephalic trunk is a quick method to exclude or identify a nrILN.

Neurosensory Differentiation and Innervation Patterning in the Human Fetal Vestibular End Organs between the Gestational Weeks 8-12.

Balance orientation depends on the precise operation of the vestibular end organs and the vestibular ganglion neurons. Previous research on the assemblage of the neuronal network in the developing fetal vestibular organ has been limited to data from animal models. Insights into the molecular expression profiles and signaling moieties involved in embryological development of the human fetal inner ear have been limited. We present an investigation of the cells of the vestibular end organs with specific focus on the hair cell differentiation and innervation pattern using an uninterrupted series of unique specimens from gestational weeks 8-12. Nerve fibers positive for peripherin innervate the entire fetal crista and utricle. While in rodents only the peripheral regions of the cristae and the extra-striolar region of the statolithic organs are stained. At week 9, transcription factors PAX2 and PAX8 were observed in the hair cells whereas PAX6 was observed for the first time among the supporting cells of the cristae and the satellite glial cells of the vestibular ganglia. Glutamine synthetase, a regulator of the neurotransmitter glutamate, is strongly expressed among satellite glia cells, transitional zones of the utricle and supporting cells in the sensory epithelium. At gestational week 11, electron microscopic examination reveals bouton contacts at hair cells and first signs of the formation of a protocalyx at type I hair cells. Our study provides first-hand insight into the fetal development of the vestibular end organs as well as their pattern of innervation by means of immunohistochemical and EM techniques, with the aim of contributing toward our understanding of balance development.

Development of the innervation of the human inner ear.

Studies on the formation of neuronal structures of the human cochlea are rare, presumptively, due to the difficult accessibility of specimens, so that most investigations are performed on mouse models. By means of immunohistochemical and transmission electron microscopic techniques, we investigated an uninterrupted series of unique specimens from gestational week 8 to week 12. We were able to demonstrate the presence of nerve fibers in the prosensory domain at gestational week 8, followed by afferent synaptogenesis at week 11. We identified PAX2 as an early marker for hair cell differentiation. Glutamine synthetase-positive peripheral glial cells occurred at the beginning of week 8. Transcription factor MAF B was used to demonstrate maturation of the spiral ganglion neurons. The early expression of tyrosine hydroxylase could be assessed. This study provides insights in the early assembly of the neural circuit and organization in humans.

Shock Wave Treatment Protects From Neuronal Degeneration via a Toll-Like Receptor 3 Dependent Mechanism: Implications of a First-Ever Causal Treatment for Ischemic Spinal Cord Injury.

BACKGROUND: Paraplegia following spinal cord ischemia represents a devastating complication of both aortic surgery and endovascular aortic repair. Shock wave treatment was shown to induce angiogenesis and regeneration in ischemic tissue by modulation of early inflammatory response via Toll-like receptor (TLR) 3 signaling. In preclinical and clinical studies, shock wave treatment had a favorable effect on ischemic myocardium. We hypothesized that shock wave treatment also may have a beneficial effect on spinal cord ischemia. METHODS AND RESULTS: A spinal cord ischemia model in mice and spinal slice cultures ex vivo were performed. Treatment groups received immediate shock wave therapy, which resulted in decreased neuronal degeneration and improved motor function. In spinal slice cultures, the activation of TLR3 could be observed. Shock wave effects were abolished in spinal slice cultures from TLR3(-/-) mice, whereas the effect was still present in TLR4(-/-) mice. TLR4 protein was found to be downregulated parallel to TLR3 signaling. Shock wave-treated animals showed significantly better functional outcome and survival. The protective effect on neurons could be reproduced in human spinal slices. CONCLUSIONS: Shock wave treatment protects from neuronal degeneration via TLR3 signaling and subsequent TLR4 downregulation. Consequently, it represents a promising treatment option for the devastating complication of spinal cord ischemia after aortic repair.

Characterization of DLK1(PREF1)+/CD34+ cells in vascular stroma of human white adipose tissue.

Sorting of native (unpermeabilized) SVF-cells from human subcutaneous (s)WAT for cell surface staining (cs) of DLK1 and CD34 identified three main populations: ~10% stained cs-DLK1+/cs-CD34-, ~20% cs-DLK1+/cs-CD34+dim and ~45% cs-DLK1-/cs-CD34+. FACS analysis after permeabilization showed that all these cells stained positive for intracellular DLK1, while CD34 was undetectable in cs-DLK1+/cs-CD34- cells. Permeabilized cs-DLK1-/cs-CD34+ cells were positive for the pericyte marker α-SMA and the mesenchymal markers CD90 and CD105, albeit CD105 staining was dim (cs-DLK1-/cs-CD34+/CD90+/CD105+dim/α-SMA+/CD45-/CD31-). Only these cells showed proliferative and adipogenic capacity. Cs-DLK1+/cs-CD34- and cs-DLK1+/cs-CD34+dim cells were also α-SMA+ but expressed CD31, had a mixed hematopoietic and mesenchymal phenotype, and could neither proliferate nor differentiate into adipocytes. Histological analysis of sWAT detected DLK1+/CD34+ and DLK1+/CD90+ cells mainly in the outer ring of vessel-associated stroma and at capillaries. DLK1+/α-SMA+ cells were localized in the CD34- perivascular ring and in adventitial vascular stroma. All these DLK1+ cells possess a spindle-shaped morphology with extremely long processes. DLK1+/CD34+ cells were also detected in vessel endothelium. Additionally, we show that sWAT contains significantly more DLK1+ cells than visceral (v)WAT. We conclude that sWAT has more DKL1+ cells than vWAT and contains different DLK1/CD34 populations, and only cs-DLK1-/cs-CD34+/CD90+/CD105+dim/α-SMA+/CD45-/CD31- cells in the adventitial vascular stroma exhibit proliferative and adipogenic capacity.

Alteration of inflammatory response by shock wave therapy leads to reduced calcification of decellularized aortic xenografts in mice†.

OBJECTIVES: Tissue-engineered xenografts represent a promising treatment option in heart valve disease. However, inflammatory response leading to graft failure and incomplete in vitro repopulation with recipient cells remain challenging. Shock waves (SWs) were shown to modulate inflammation and to enhance re-epithelialization. We therefore aimed to investigate whether SWs could serve as a feasible adjunct to tissue engineering. METHODS: Porcine aortic pieces were decellularized using sodium deoxycholate and sodium dodecylsulphate and implanted subcutaneously into C57BL/6 mice (n = 6 per group). The treatment (shock wave therapy, SWT) group received SWs (0.1 mJ/mm(2), 500 impulses, 5 Hz) for modulation of inflammatory response directly after implantation; control animals remained untreated (CTR). Grafts were harvested 72 h and 3 weeks after implantation and analysed for inflammatory cytokines, macrophage infiltration and polarization, osteoclastic activity and calcification. Transmission electron microscopy (TEM) was performed. Endothelial cells (ECs) were treated with SWs and analysed for macrophage regulatory cytokines. In an ex vivo experimental set-up, decellularized porcine aortic valve conduits were reseeded with ECs with and without SWT (0.1 mJ/mm(2), 300 impulses, 3 Hz), fibroblasts as well as peripheral blood mononuclear cells (all human) and tested in a pulsatile flow perfusion system for cell coverage. RESULTS: Treated ECs showed an increase of macrophage migration inhibitory factor and macrophage inflammatory protein 1ß, whereas CD40 ligand and complement component C5/C5a were decreased. Subcutaneously implanted grafts showed increased mRNA levels of tumour necrosis factor α and interleukin 6 in the treatment group. Enhanced repopulation with recipient cells could be observed after SWT. Augmented macrophage infiltration and increased polarization towards M2 macrophages was observed in treated animals. Enhanced recruitment of osteoclastic cells in proximity to calcified tissue was found after SWT. Consequently, SWT resulted in decreased areas of calcification in treated animals. The reseeding experiment revealed that fibroblasts showed the best coverage compared with other cell types. Moreover, SW-treated ECs exhibited enhanced repopulation compared with untreated controls. CONCLUSIONS: SWs reduce the calcification of subcutaneously implanted decellularized xenografts via the modulation of the acute macrophage-mediated inflammatory response and improves the in vitro repopulation of decellularized grafts. It may therefore serve as a feasible adjunct to heart valve tissue engineering.

Development of an innovative 3D cell culture system to study tumour--stroma interactions in non-small cell lung cancer cells.

INTRODUCTION: We describe a novel 3D co-culture model using non-small cell lung cancer (NSCLC) cell lines in combination with lung fibroblasts. This model allows the investigation of tumour-stroma interactions and addresses the importance of having a more in vivo like cell culture model. METHODS: Automation-compatible multi-well hanging drop microtiter plates were used for the production of 3D mono- and co-cultures. In these hanging drops the two NSCLC cell lines A549 and Colo699 were cultivated either alone or co-cultured with lung fibroblasts. The viability of tumour spheroids was confirmed after five and ten days by using Annexin V/Propidium Iodide staining for flow-cytometry. Tumour fibroblast spheroid formation was characterized by scanning electron microscope (SEM), semi-thin sections, fluorescence microscope and immunohistochemistry (IHC). In addition to conventional histology, protein expression of E-Cadherin, vimentin, Ki67, fibronectin, cytokeratin 7 and α-smooth muscle actin (α-SMA) was investigated by IHC. RESULTS: Lower viability was observed in A549 monocultures compared to co-cultures, whereas Colo699 monocultures showed better viability compared to co-cultures. Ki67 expression varied significantly between mono- and co-cultures in both tumour cell lines. An increase of vimentin and decreased E-Cadherin expression could be detected during the course of the cultivation suggesting a transition to a more mesenchymal phenotype. Furthermore, the fibroblast cell line showed an expression of α-SMA only in co-culture with the cancer cell line A549, thereby indicating a mesenchymal to mesenchymal shift to an even more myofibroblast phenotype. CONCLUSION: We demonstrate that our method is a promising tool for the generation of tumour spheroid co-cultures. Furthermore, these spheroids allow the investigation of tumour-stroma interactions and a better reflection of in vivo conditions of cancer cells in their microenvironment. Our method holds potential to contribute to the development of anti-cancer agents and support the search for biomarkers.

Histomorphometric evaluation of ischemia-reperfusion injury and the effect of preservation solutions histidine-tryptophan-ketoglutarate and University of Wisconsin in limb transplantation.

BACKGROUND: The effect of cold ischemia (CI) in vascularized composite allotransplantation is unknown. We herein assess tissue-specific damage, acceptable CI time, and the effect of preservation solutions in a syngenic rat hindlimb transplant model. METHODS: Lewis rat limbs were flushed and stored for 2, 10, or 30 hr CI in saline, histidine-tryptophan-ketoglutarate or University of Wisconsin preservation solution before transplantation. Morphologic alterations, inflammation, and damage of the individual tissues were analyzed on day 10 using histomorphology, confocal, light, and transmission-electron microscopy. RESULTS: Two-hour CI led to mild inflammation of tissues on day 10, whereas 10-hr and 30-hr CI resulted in massive inflammation and tissue damage. Although muscle was mainly affected after prolonged CI (≥10 hr), nerve was affected in all CI groups. A perineural cell infiltrate, hypercellular appearance, pronounced vacuolization, and mucoid degeneration, appearing as Wallerian degeneration, were observed. Staining with propidium iodide and Syto 16 revealed a decrease in viable muscle cell nuclei in the anterior tibial muscle on day 10 in all groups, which was most pronounced in 10-hr and 30-hr CI animals. Transmission-electron microscopy indicated that a large number of mitochondria were degenerated in the 10-hr and 30-hr CI groups. Histidine-tryptophan-ketoglutarate preservation solution slightly decreased inflammation and tissue damage compared to University of Wisconsin-treated and saline-treated animals, especially in skin and muscle when CI times did not exceed 10 hr. CONCLUSION: Severe inflammation and tissue damage are observed after prolonged CI in muscle and nerve. Ischemia times in vascularized composite allotransplantation should be kept as short as possible and certainly below 10 hr.

The male urethra: spatiotemporal distribution of molecular markers during early development.

The organogenesis of the male human urethra is still a subject of controversy. Although many studies have been conducted, the mechanisms of urethral development still need further investigation to clarify questions concerning the sequences in its development. Our aim has been to elucidate the spatiotemporal distribution of relevant immunohistochemical indicators during the development of the male urethral epithelium and its adjacent mesenchyme. Therefore, we analyzed male human embryos and foetuses between the 6th and 15th week after fertilization using histological and immunohistochemical methods. Monoclonal antibodies raised against cytokeratins (CKs) 7, 8, 13 and 17 as well as Ki67, E-Cadherin, p63, uroplakin III, smooth muscle actin (SMA) and vimentin were applied. Our results revealed that epithelial differentiation starts prior to the rupture of the cloacal membrane. At weeks (W) 8-9 the epithelium became transitional over the whole length of the elongating urethra. The urothelial staining pattern of uroplakin III receded continually, and, at the end of W 11, it had receded in proximal direction to the bladder neck comparable to the epithelial appearance in adults. The urogenital sinus epithelium provided the Wolffian duct with p63-positive cells, leading to the suggestion that the development of the male inner genitals requires a cellular stimulus by this very epithelium. CK 17-positive cells, which were described as epithelial stem cells, could be found in the extending urethral plate. This facilitates new insight into the pathogenesis and treatment of hypospadias, which is one of the most common malformations in newborn males.

Novel immunohistochemical data indicate that the female foetal urethra is more than an epithelial tube.

The female urethra has often been neglected in previous studies on the development of the human urogenital system. Our aim has been to reach a consensus on the organogenesis of the female urethra and the vagina with respect to interactions between the epithelia with different evolutionary origins. Therefore we tried to clarify open questions on the spatiotemporal distribution of molecular markers raised against mesenchymal and epithelial structures within the developing human female urethra. Furthermore, we draw comparisons regarding gender-specific aspects in urethral development. To this effect, we used molecular markers such as different cytokeratins (CKs), p63, Ki67, uroplakin III, E-cadherin, vimentin, smooth muscle actin (SMA), cleaved caspase 3 and paired box gene 2 (PAX 2) to phenotype developmental changes. Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling (TUNEL) assay was additionally performed to reveal apoptosis. We examined different gestational stages starting from week (W) 8 until W 15. Immunohistochemistry showed a distinct staining pattern for p63 and CK17, both markers for stem cells, ensuing from the urogenital sinus (UGS) proceeding into the Muellerian duct (MD). This was observed throughout development and might be a stimulus for the formation of the vaginal anlagen that derive from the MD. In the attachment area of the MD we detected a conglomeration of cells with different embryonic origins. The epithelium of the UGS became transitional at W 9 after fertilization, and the differentiation advanced in a cranial to caudal direction. The paraurethral glands showed a slightly different staining profile than the urethral epithelium, which may be able to explain why carcinomas of these structures display various histological appearances. In addition, we could show that during the development of the female urogenital system the primary incidence is the formation of the urethra. This is followed by the establishment of the vagina, which clearly depends on the proper differentiation of the UGS/urethra.