Cadaveric Tissue Research Articles

Direct mechanical characterization of prostate tissue-a systematic review.

Direct mechanical characterization of tissue is the application of engineering techniques to biological tissue to ascertain stiffness or elasticity, which can change in response to disease states. A number of papers have been published on the application of these techniques to prostate tissue with a range of results reported. There is a marked variability in the results depending on testing techniques and disease state of the prostate tissue. We aimed to clarify the utility of direct mechanical characterization of prostate tissue in identifying disease states. A systematic review of the published literature regarding direct mechanical characterization of prostate tissue was undertaking according to PRISMA guidelines. A variety of testing methods have been used, including compression, indentation, and tensile testing, as well as some indirect testing techniques, such as shear-wave elastography. There is strong evidence of significant stiffness differences between cancerous and non-cancerous prostate tissue, as well as correlations with prostate cancer stage. There is a correlation with increasing prostate stiffness and increasing lower urinary tract symptoms in patients with benign prostate hyperplasia. There is a wide variation in the testing methods and protocols used in the literature making direct comparison between papers difficult. Most studies utilise ex-vivo or cadaveric tissue, while none incorporate in vivo testing. Direct mechanical assessment of prostate tissue permits a better understanding of the pathological and physiological changes that are occurring within the tissue. Further work is needed to include prospective and in vivo data to aid medical device design and investigate non-surgical methods of managing prostate disease.

Identification and characterization of dendritic cell subtypes in preserved and cultured cadaveric human corneolimbal tissue on amniotic membrane.

Rejection is the leading cause of failure of limbal allogafts. Resident dendritic cell (DC) maturation plays a critical role in host allosensitization. There are two lineages: myeloid (mDC) and lymphoid (pDC), with different biological properties. The aim was to analyse the distribution of DC subtypes in limbal explant cultures on amniotic membrane (AM), cultivated on either the epithelial or stromal side and to compare the results with directly isolated cells from cadaveric whole corneoscleral tissue divided into specific areas. The expression of CD11c (mDC), CD303/CD123 (pDC) and costimulatory molecules CD80, CD86 and activation markers HLA-DR, CD83 was investigated by flow cytometry. Additionally, the corneal epithelium marker CK12 and ABCB5, a new epithelial stem cell marker, were investigated. Cells positive for pDC and mDC markers were found in all examined areas, with a nonsignificant prevalence of pDC. In limbal explant cultures on AM, the percentage of pDC and mDC was similar, with no statistically significant difference between cultures on epithelial or stromal sides of AM. However, with exvivo limbal explant cultivation on AM, the pDC content declined significantly (p<0.05) and the ABCB5 marker was likewise statistically significantly reduced. This is the first study to characterize the distribution of pDC and mDC subsets in cultured and noncultured human corneolimbal tissue. Additionally, ABCB5 positive cells were identified. These findings might be important for future strategies, allowing preparation of corneolimbal allografts with optimal stem cell content for a longer lasting therapeutic effect.

The cat as a naturally occurring model of renal interstitial fibrosis: Characterisation of primary feline proximal tubular epithelial cells and comparative pro-fibrotic effects of TGF-β1.

Chronic kidney disease (CKD) is common in both geriatric cats and aging humans, and is pathologically characterised by chronic tubulointerstitial inflammation and fibrosis in both species. Cats with CKD may represent a spontaneously occurring, non-rodent animal model of human disease, however little is known of feline renal cell biology. In other species, TGF-β1 signalling in the proximal tubular epithelium is thought to play a key role in the initiation and progression of renal fibrosis. In this study, we first aimed to isolate and characterise feline proximal tubular epithelial cells (FPTEC), comparing them to human primary renal epithelial cells (HREC) and the human proximal tubular cell line HK-2. Secondly, we aimed to examine and compare the effect of human recombinant TGF-β1 on cell proliferation, pro-apoptotic signalling and genes associated with epithelial-to-mesenchymal transition (EMT) in feline and human renal epithelial cells. FPTEC were successfully isolated from cadaverous feline renal tissue, and demonstrated a marker protein expression profile identical to that of HREC and HK-2. Exposure to TGF-β1 (0–10 ng/ml) induced a concentration-dependent loss of epithelial morphology and alterations in gene expression consistent with the occurrence of partial EMT in all cell types. This was associated with transcription of downstream pro-fibrotic mediators, growth arrest in FPTEC and HREC (but not HK-2), and increased apoptotic signalling at high concentrations of TGF- β1. These effects were inhibited by the ALK5 (TGF-β1RI) antagonist SB431542 (5 μM), suggesting they are mediated via the ALK5/TGF-β1RII receptor complex. Taken together, these results suggest that TGF-β1 may be involved in epithelial cell dedifferentiation, growth arrest and apoptosis in feline CKD as in human disease, and that cats may be a useful, naturally occurring model of human CKD.

Constructing a Novel Three-Dimensional Biomimetic Corneal Endothelium Graft by Culturing Corneal Endothelium Cells on Compressed Collagen Gels.

Background:Endothelium allotransplantation is the primary treatment for corneal decompensation. The worldwide shortage of donor corneal tissue has led to increasing pressure to seek an alternative for surgical restoration of corneal endothelium. Compressed collagen (CC) gels have excellent biocompatibility, simple preparation course and easy to be manipulated. This study aimed to form a new biomimetic endothelium graft by CC.Methods:We expanded bovine corneal endothelial cells (B-CECs) on laminin-coated CC to form a biomimetic endothelium graft. Scanning electron microscope was used for ultrastructural analysis and tight junction protein ZO-1 expression was tested by immunohistochemistry.Results:The biomimetic endothelium graft, we conducted had normal cell morphology, ultrastructure and higher cell density (3612.2 ± 43.4 cells/mm2). ZO-1 localization at B-CECs membrane indicated the bioengineered graft possess the basic endothelium function.Conclusions:A biomimetic endothelium graft with B-CECs expanded on CC sheet was constructed, which possessed cells' morphology similar to that of in vivo endothelial cells and specific basic function of endothelium layer. This method provided the possibility of using one donor's cornea to form multiple uniformed endothelium grafts so as to overcome the shortage of cadaveric cornea tissue.

Segmental bone replacement via patient-specific, three-dimensional printed bioresorbable graft substitutes and their use as templates for the culture of mesenchymal stem cells under mechanical stimulation at various frequencies.

The treatment of large segmental bone defects remains a challenge as infection, delayed union, and nonunion are common postoperative complications. A three-dimensional printed bioresorbable and physiologically load-sustaining graft substitute was developed to mimic native bone tissue for segmental bone repair. Fabricated from polylactic acid, this graft substitute is novel as it is readily customizable to accommodate the particular size and location of the segmental bone of the patient to be replaced. Inspired by the structure of the native bone tissue, the graft substitute exhibits a gradient in porosity and pore size in the radial direction and exhibit mechanical properties similar to those of the native bone tissue. The graft substitute can serve as a template for tissue constructs via seeding with stem cells. The biocompatibility of such templates was tested under in vitro conditions using a dynamic culture of human mesenchymal stem cells. The effects of the mechanical loading of cell-seeded templates under in vitro conditions were assessed via subjecting the tissue constructs to 28 days of daily mechanical stimulation. The frequency of loading was found to have a significant effect on the rate of mineralization, as the alkaline phosphatase activity and calcium deposition were determined to be particularly high at the typical walking frequency of 2 Hz, suggesting that mechanical stimulation plays a significant role in facilitating the healing process of bone defects. Utilization of such patient-specific and biocompatible graft substitutes, coupled with patient's bone marrow cells seeded and exposed to mechanical stimulation of 2 Hz have the potential of reducing significant volumes of cadaveric tissue required, improving long-term graft stability and incorporation, and alleviating financial burdens associated with delayed or failed fusions of long bone defects.

Building Ultrasound Phantoms With Modified Polyvinyl Chloride: A Comparison of Needle Insertion Forces and Sonographic Appearance With Commercial and Traditional Simulation Materials.

Training using ultrasound phantoms allows for safe introduction to clinical skills and is associated with improved in-hospital performance. Many materials have been used to simulate human tissue in phantoms including commercial manikins, agar, gelatin, and Ballistics Gel; however, phantom tissues could be improved to provide higher-fidelity ultrasound images or tactile sensation. This article describes a novel phantom tissue mixture of a modified polyvinyl chloride (PVC) polymer, mineral oil, and chalk powder and evaluates needle cutting and ultrasonic properties of the modified PVC polymer mixture compared with a variety of phantom tissues. The first experiment measured axial needle forces of a needle insertion into nine phantom materials, including three formulations of modified PVC. The second experiment used a pairwise comparison survey of ultrasound images to determine the perceived realism of phantom ultrasound images. It was found that the materials of Ballistics Gel and one of the PVC mixtures provide stiff force feedback similar to cadaver tissue. Other phantom materials including agar and gelatin provide very weak unrealistic force feedback. The survey results showed the PVC mixtures being viewed as the most realistic by the survey participants, whereas agar and Ballistics Gel were seen as the least realistic. The realism in cutting force and ultrasound visualization was determined for a variety of phantom materials. Novel modified PVC polymer has great potential for use in ultrasound phantoms because of its realistic ultrasound imaging and modifiable stiffness. This customizability allows for easy creation of multilayer tissue phantoms.

The Barrow Biomimetic Spine: Comparative Testing of a 3D-Printed L4-L5 Schwab Grade 2 Osteotomy Model to a Cadaveric Model.

IntroductionThe Barrow Biomimetic Spine project is an ongoing effort to develop a three-dimensional (3D)-printed synthetic spine model with high anatomical and biomechanical fidelity to human tissue. The purpose of this study was to evaluate the biomechanical performance of an L4-L5 3D-printed synthetic spine model in a lordotic correction test after Schwab grade 2 osteotomies as compared to human cadaveric spines that have undergone the same osteotomies and lordotic correction.MethodsTen different L4-L5 synthetic spine models were 3D printed. Each print varied in either the material used for the soft tissue components, the infill density of the bony and soft tissue structures, the pre-correction disc height, or the model orientation on the print bed. Each print was instrumented with pedicle screws and underwent a Schwab grade 2 osteotomy. Changes in disc height measurements and end-plate angle were compared against cadaveric data acquired using the same study method.ResultsA simple linear correlation analysis demonstrated that for horizontally printed models using PolyFlex (Polymaker, New York, NY, USA)(models 1-3, 8, 10), the pre-correction posterior disc height and lordotic correction were moderately correlated (r = 0.56), but this correlation did not achieve statistical significance (P = 0.12). Regression analysis demonstrated a very strong correlation between lordotic correction and change in posterior disc height (r = 0.92, P < 0.001). Models printed either vertically (models 4-6) or with low bone density and high soft tissue density (model 10) appeared to perform the most similarly to the cadaveric tissue.DiscussionThe 3D-printed synthetic spine models demonstrated predictable and reliable performance in a lordotic correction test based on their respective material qualities and print densities. The print variables tested further demonstrated that this model is capable of achieving high biomechanical fidelity to cadaveric tissue when subjected to the same lordotic correction test after Schwab grade 2 osteotomies.

A rapid histology station in the gross laboratory can assist students in understanding the value of microanatomy

The integration of gross anatomy and histopathology is a recent trend in anatomical sciences education. For this study, a rapid histology station was set up in the gross anatomy laboratory that allowed medical students to create and stain microscope slides directly from cadaveric tissues. The students (n=200) were instructed on the purpose behind tissue preparation and routine hematoxylin and eosin staining methods. Students were also given access to a microscope to examine the crude architecture of the tissue immediately after slide preparation. The slides were utilized during the next semester histology course for clinical application and self‐directed activities. A survey was given to participants to determine the impact that slide preparation activities have on medical students' understanding of microanatomy and also to assess whether using a rapid histology station can assist in horizontal integration of the anatomical sciences. The surveys included both restricted response items (n=20) and open‐ended items (n=5) that necessitated a quantitative and qualitative analysis. Thematic analysis of the qualitative data resulted in several key themes being identified and suggest that student involvement in histology slide preparation can benefit students in unique educational ways beyond the traditional identification of anatomic structures.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Situs Inversus Totalis in a 96‐Year‐Old Female Cadaver: Genetic Insights

BackgroundSitus inversus totalis is a complete reversal of thoracic and abdominal organs. Since only 25% of individuals with situs inversus have primary ciliary dyskinesia (PCD), which is a genetically heterogeneous disorder affecting motile cilia and is thought to be one of the underlining mechanisms of situs inversus, the majority of the latter cases still await their mechanistic elucidation. The present study reports the complete reversal of internal organs in a female cadaver 96 years of age and uses state‐of‐the‐art Next Generation Sequencing (NGS) to detect novel genetic mutations associated with situs inversus totalis.ResultsOur examination of the individual's body revealed that the visceral organs of the abdomen and thorax were mirror‐imaged to normal anatomy. The apex of the heart was directed to the right with a trilobed left lung and bilobed right lung. The liver was situated on the left side of the body, while the spleen and stomach were right sided. Several abdominal vasculature anomalies were also identified. In particular, the common hepatic artery branches from the superior mesenteric artery and the cystic artery branches from the right hepatic artery. There was also a common trunk that gives off the left gastric artery and an accessory right hepatic artery. In order to gain new insights into the molecular mechanisms that govern determination of the left/right asymmetry during the internal organ development, the genetic screen was performed using DNA extracted from the cadaveric tissue and the exome sequencing on the Illumina NGS platform.ConclusionThe present case can be described as situs inversus totalis which is accompanied by abnormal development of abdominal vasculature. The respective genetic analysis could point to a novel and additional to PCD mechanism(s) responsible for the aberrant visceral organ patterning and vascular development in humans.Support or Funding InformationThis study was supported by the Center for Anatomical Science and Education, Department of Surgery, Saint Louis University School of Medicine.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sagittal Craniosynostosis and Related Cranial Anomalies: Genetic Insights

BackgroundSagittal craniosynostosis (scaphocephaly) is a pathologic condition that results in premature fusion of the sagittal suture restricting the transverse growth of the skull leading to elevated intracranial pressure and consequent neurodevelopmental delay. It can occur most commonly as an isolated event resulting in nonsyndromic craniosynostosis, or it can occur less commonly in conjunction with other anomalies resulting in syndromic craniosynostosis. Although in past years close attention was paid by researchers regarding the mechanisms that govern development of craniosynostosis, much more remains to be learned about this cranial anomaly, in particular, the genetic mechanisms associated with scaphocephaly. The clearer understanding of the latter not only could shed more light on the respective mechanisms but could also help to improve and predict better outcomes of the respective corrective clinical procedures.ResultsThe present study reports a unique case of a male cadaver 56 years of age with sagittal craniosynostosis with a 0.56 cranial vault index as measured from respective radiographic images. Upon closer examination of the individual's head it was concluded that he underwent, most likely early in his life, a sagittal strip synostectomy with replacement. The additional maxillofacial anomalies included edentulous, mandibular prognathism with class 3 malocclusion and 15 mm of negative overjet, and exostosis of the hard palate. The latter was preliminary characterized as torus palatinus. One of the most interesting features of the present case was the abnormal appearance of the replacement bone strip and its vertical displacement that were accompanied by a presence of abnormal dura and venous sinuses with no brain indentations on the dural surface of the strip. Histologic analyses of cranial soft and hard tissues should help to clarify a nature of the respective pathologies. In order to better understand molecular mechanism(s) responsible for the development of sagittal craniosynostosis with the particular maxillofacial anomalies, the gene coding region (exome) of DNA extracted from the cadaveric tissue was screened for putative mutations employing Illumina Next Generation Sequencing Platform. This will help to unveil new genetic variations associated with the aberrant skull development in humans and optimize clinical approaches for its correction.ConclusionThe current case most likely represents syndromic sagittal craniosynostosis where surgical intervention was mainly unsuccessful resulting in abnormal development of the replacement bone strip and intracranial tissue.Support or Funding InformationThis study was supported by the Center for Anatomical Science and Education, Department of Surgery, Saint Louis University School of Medicine.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Development and Evaluation of a Tissue-Engineered Fibrin-based Canine Mitral Valve Three-dimensional Cell Culture System

Myxomatous mitral valve disease is the most common cardiac disease of the dog, but examination of the associated cellular and molecular events has relied on the use of cadaveric valve tissue, in which functional studies cannot be undertaken. The aim of this study was to develop a three-dimensional (3D) cell co-culture model as an experimental platform to examine disease pathogenesis. Mitral valve interstitial (VIC) and endothelial (VEC) cells were cultured from normal and diseased canine (VIC only) valves. VICs were embedded in a fibrin-based hydrogel matrix and one surface was lined with VECs. The 3D static cultures (constructs) were examined qualitatively and semiquantitatively by light microscopy, immunofluorescence microscopy and protein immunoblotting. Some constructs were manipulated and the endothelium damaged, and the response examined. The construct gross morphology and histology demonstrated native tissue-like features and comparable expression patterns of cellular (α-smooth muscle actin [SMA] and embryonic smooth muscle myosin heavy chain [SMemb]) and extracellular matrix associated markers (matrix metalloproteinase [MMP]-1 and MMP-3), reminiscent of diseased valves. There were no differences between constructs containing normal valve VICs and VECs (type 1) and those containing diseased valve VICs and normal valve VECs (type 2). Mechanical manipulation and endothelial damage (type 3) tended to decrease α-SMA and SMemb expression, suggesting reversal of VIC activation, but with retention of SMemb+ cells adjacent to the wounded endothelium consistent with response to injury. Fibrin-based 3D mitral valve constructs can be produced using primary cell cultures derived from canine mitral valves, and show a phenotype reminiscent of diseased valves. The constructs demonstrate a response to endothelial damage indicating their utility as experimental platforms.

Picosecond Infrared Laser (PIRL) Application in Stapes Surgery-First Experience in Human Temporal Bones.

Objective:Using a contact-free laser technique for stapedotomy reduces the risk of mechanical damage of the stapes footplate. However, the risk of inner ear dysfunction due to thermal, acoustic, or direct damage has still not been solved. The objective of this study was to describe the first experiences in footplate perforation in cadaver tissue performed by the novel Picosecond-Infrared-Laser (PIRL), allowing a tissue preserving ablation.Patients and Intervention:Three human cadaver stapes were perforated using a fiber-coupled PIRL. The results were compared with footplate perforations performed with clinically applied Er:YAG laser. Therefore, two different laser energies for the Er:YAG laser (30 and 60 mJ) were used for footplate perforation of three human cadaver stapes each.Main Outcome Measure:Comparisons were made using histology and environmental scanning electron microscopy (ESEM) analysis.Results:The perforations performed by the PIRL (total energy: 640–1070 mJ) revealed a precise cutting edge with an intact trabecular bone structure and no considerable signs of coagulation. Using the Er:YAG-Laser with a pulse energy of 30 mJ (total energy: 450–600 mJ), a perforation only in the center of the ablation zone was possible, whereas with a pulse energy of 60 mJ (total energy: of 195–260 mJ) the whole ablation zone was perforated. For both energies, the cutting edge appeared irregular with trabecular structure of the bone only be conjecturable and signs of superficial carbonization.Conclusion:The microscopic results following stapes footplate perforation suggest a superiority of the PIRL in comparison to the Er:YAG laser regarding the precision and tissue preserving ablation.

Characterisation of feline renal cortical fibroblast cultures and their transcriptional response to transforming growth factor \u03b21

BackgroundChronic kidney disease (CKD) is common in geriatric cats, and the most prevalent pathology is chronic tubulointerstitial inflammation and fibrosis. The cell type predominantly responsible for the production of extra-cellular matrix in renal fibrosis is the myofibroblast, and fibroblast to myofibroblast differentiation is probably a crucial event. The cytokine TGF-β1 is reportedly the most important regulator of myofibroblastic differentiation in other species. The aim of this study was to isolate and characterise renal fibroblasts from cadaverous kidney tissue of cats with and without CKD, and to investigate the transcriptional response to TGF-β1.ResultsCortical fibroblast cultures were successfully established from the kidney tissue of cats with normal kidney function (FCF) and cats with chronic kidney disease (CKD-FCF). Both cell types expressed the mesenchymal markers vimentin, CD44 and CD29, and were negative for the epithelial marker cytokeratin, mesangial cell marker desmin and endothelial cell marker vWF. Only CKD-FCF expressed VCAM-1, a cell marker associated with inflammation. Incubation with TGF-β1 (0–10 ng/ml) induced a concentration dependent change in cell morphology, and upregulation of myofibroblast marker gene α-SMA expression alongside collagen 1α1, fibronectin, TGF-β1 and CTGF mRNA. These changes were blocked by the TGF-β1 receptor 1 antagonist SB431542 (5 μM).ConclusionsFCF and CKD-FCF can be cultured via a simple method and represent a model for the investigation of the progression of fibrosis in feline CKD. The findings of this study suggest TGF-β1 may be involved in fibroblast-myofibroblast transition in feline CKD, as in other species.

Enhanced tendon-to-bone repair through adhesive films

Tendon-to-bone surgical repairs have unacceptably high failure rates, possibly due to their inability to recreate the load transfer mechanisms of the native enthesis. Instead of distributing load across a wide attachment footprint area, surgical repairs concentrate shear stress on a small number of suture anchor points. This motivates development of technologies that distribute shear stresses away from suture anchors and across the enthesis footprint. Here, we present predictions and proof-of-concept experiments showing that mechanically-optimized adhesive films can mimic the natural load transfer mechanisms of the healthy attachment and increase the load tolerance of a repair. Mechanical optimization, based upon a shear lag model corroborated by a finite element analysis, revealed that adhesives with relatively high strength and low stiffness can, theoretically, strengthen tendon-to-bone repairs by over 10-fold. Lap shear testing using tendon and bone planks validated the mechanical models for a range of adhesive stiffnesses and strengths. Ex vivo human supraspinatus repairs of cadaveric tissues using multipartite adhesives showed substantial increase in strength. Results suggest that adhesive-enhanced repair can improve repair strength, and motivate a search for optimal adhesives. Statement of SignificanceCurrent surgical techniques for tendon-to-bone repair have unacceptably high failure rates, indicating that the initial repair strength is insufficient to prevent gapping or rupture. In the rotator cuff, repair techniques apply compression over the repair interface to achieve contact healing between tendon and bone, but transfer almost all force in shear across only a few points where sutures puncture the tendon. Therefore, we evaluated the ability of an adhesive film, implanted between tendon and bone, to enhance repair strength and minimize the likelihood of rupture. Mechanical models demonstrated that optimally designed adhesives would improve repair strength by over 10-fold. Experiments using idealized and clinically-relevant repairs validated these models. This work demonstrates an opportunity to dramatically improve tendon-to-bone repair strength using adhesive films with appropriate material properties.

A model to evaluate Pauwels type III femoral neck fractures.

While many femoral neck fractures can be reliably treated with surgical intervention, Pauwels III femoral neck fractures in the young adult population continue to be a challenging injury, and there is no consensus on optimal treatment. As such, there are past and ongoing biomechanical studies to evaluate the fixation provided by different constructs for this inherently unstable fracture. While many investigations rely on cadavers to evaluate the biomechanical performance of a construct, significant inter-subject variability can confound the analysis. Biomechanical femur analogs are being used more frequently due to more consistent mechanical properties; however, they have not been stringently evaluated for morphology or suitability for instrumentation. This study sought to determine the variability among composite femoral analogs as well as consistently create a Pauwels III injury and instrument the analogs without the need for fluoroscopic guidance. In total, 24 fourth-generation composite femoral analogs were evaluated for femoral height, neck-shaft angle, anteversion, and cortical thickness. A method was developed to simulate a Pauwels III fracture and to prepare three different constructs: an inverted triangle of cannulated screws, a sliding hip screw, and a hybrid inverted triangle with cannulated screws and a sliding hip screw. Radiographs were utilized to evaluate the variation in implant position. All but one of the morphological parameters varied by <1%. The tip-to-apex distance for all sliding hip screw hardware was 18.8 ± 3.3 mm, and all relevant cannulated screw distances were within 5 mm of the adjacent cortex. All screws were parallel, on average, within 1.5° on anterior-posterior and lateral films. Fourth-generation composite femora were found to be morphologically consistent, and it is possible to consistently instrument the analogs without the use of fluoroscopy. This analog and hardware implantation model could serve as a screening model for new fracture repair constructs without the need for cadaveric tissues or radiologic technology.

Autologous Bone Harvest in Anterior Cervical Spine Surgery: A Quantitative and Qualitative InVitro Analysis of Cadaveric Tissue.

The cervical spine may be used as a harvesting site of local autograft material during anterior cervical discectomy and fusion procedures. We analyzed the quality and composition of bone grafts obtained from different parts of the cervical vertebrae in a cadaveric model. Five fresh adult human cadavers with intact cervical spines were used. Using a Smith-Robinson anterior approach to expose C4-5 and C5-6 vertebrae, samples from 4 vertebral sites were harvested under a microscope. Anterior osteophytes were removed piecemeal by a Leksell rongeur (sample A). A high-speed burr was used to drill the endplates of C4-5 and C5-6 (sample C) and uncovertebral joints of C4-5 (sample B) and C5-6 (sample D). Then 20 slides (4 per cadaver) were prepared and analyzed. Tissue fragmentation was associated with use of the high-speed burr. Sample A had minimal tissue fragmentation. Samples B-D showed moderate to high fragmentation. Cartilage was found in all samples. Of the 20 slides, 6 contained soft tissues (sample A in 4, sample D in 2). Disc material was identified in 6 slides (sample A in 1, sample B in 4, sample D in 1). Sample A had the greatest number of intact osteocytes and chondrocytes, and sample B had the least. Anterior osteophytes provide the highest number of osteocytes, with the highest osteocyte/chondrocyte ratio. Osteocyte viability is a function of vertebral body site and collection technique, with fragmentation caused by use of a high-speed burr decreasing the number of viable osteocytes.

Viral Transduction of Schwann Cells for Peripheral Nerve Repair.

Schwann cells are the primary inducers of regeneration of the peripheral nervous system. Schwann cells can be isolated from adult peripheral nerves, expanded in large numbers, and genetically transduced by viral vectors in vitro prior to their use in vivo. Here we describe how to use lentiviral vectors to transduce primary Schwann cells in vitro. We also describe how cultured Schwann cells can be used in conjunction with decellularized peripheral nerve sheaths prepared by multiple freeze thawing of peripheral nerve tissue. This process depletes all native cells from the nerve sheath but maintains basal lamina integrity and flexibility. A major advantage of using these decellularized nerve sheaths in repair strategies is that they can be obtained from cadaveric tissue and therefore do not require patient matching because the immune response is generated from the intrinsic cells and not the sheath itself. The patient's own cells can then be used to repopulate the decellularized peripheral nerve sheath. Our technique described in this chapter uses decellularized nerve sheaths which are repopulated with extrinsic Schwann cells previously grown in vitro. The Schwann cells can also be engineered in multiple ways, for example, to secrete bioactive proteins beneficial to axonal regeneration.

Distribution of Interleukin-22-secreting Immune Cells in Conjunctival Associated Lymphoid Tissue.

PurposeInterleukin (IL)-22 is a cytokine involved in epithelial cell regeneration. Currently, no research studies have analyzed the distribution of the three distinct IL-22–secreting cell populations in human or mouse conjunctiva. This study investigated the distribution of the three main populations of IL-22–secreting immune cells, αβ Th cells, γδ T cells, or innate cells (innate lymphoid cells [ILCs] or natural killer cells), in conjunctival associated lymphoid tissues (CALTs) in human and mouse models.MethodsWe collected discarded cadaveric bulbar conjunctival tissue specimens after preservation of the corneo-limbal tissue for keratoplasty from four enucleated eyes of the domestic donor. The bulbar conjunctiva tissue, including the cornea from normal (n = 27) or abraded (n = 4) B6 mice, were excised and pooled in RPMI 1640 media. After the lymphoid cells were gated in forward and side scattering, the αβ Th cells, γδ T cells, or innate lymphoid cells were positively or negatively gated using anti-CD3, anti-γδ TCR, and anti–IL-22 antibodies, with a FACSCanto flow cytometer.ResultsIn normal human conjunctiva, the percentage and number of cells were highest in αβ Th cells, followed by γδ T cells and CD3− γδ TCR − IL-22+ innate cells (presumed ILCs, pILCs) (Kruskal-Wallis test, p = 0.012). In normal mice keratoconjunctiva, the percentage and total number were highest in γδ T cells, followed by αβ Th cells and pILCs (Kruskal-Wallis test, p = 0.0004); in corneal abraded mice, the population of αβ Th cells and pILCs tended to increase.ConclusionsThis study suggests that three distinctive populations of IL-22–secreting immune cells are present in CALTs of both humans and mice, and the proportions of IL-22+αβ Th cells, γδ T cells, and pILCs in CALTs in humans might be differently distributed from those in normal mice.

High rate failure properties of human aortic tissue under longitudinal extension

Understanding the failure properties of human aortic tissue at high strain rate loading is important to understand the mechanism of traumatic rupture of aorta (TRA). This study reports 18 uniaxial tensile tests performed on human aortic tissue in the longitudinal direction. Rectangular specimens were obtained from cadaveric human aortic tissue. Uniaxial tensile tests were performed at target strain rates of 0.001 s–1, 65 s–1, 130 s–1and 190 s–1 to failure. High-speed video was used to measure the gripper to gripper displacement. Failure stress and strain were calculated. The load-deformation relationship of aorta is found to be nonlinear and strain rate dependent with higher failure stress and lower effective failure engineering strains at higher strain rates. Across tests, the failure stress ranged from 0.86 MPa to 1.86 MPa and effective failure strain from 13.52% to 10.80%.

Regional and age-dependent residual strains, curvature, and dimensions of the human ureter.

The ureters are retroperitoneal structures controlling urine transport from the kidneys to the bladder. Because of the relative scarcity of data on the biomechanical properties of human ureter and the established importance of knowing these properties for understanding its physiology, we initiated biomechanical studies in cadaveric tissue. Herein, we report definite zero-stress/no-load geometrical characterization at 15 regions along the ureter of human cadavers aged 23-82 years, estimating the opening angle, circumferential residual strains, axial curvature, and dimensional parameters. Opening angle decreased along the proximal 25% of ureter, increased and reached a maximum near the mid-ureter, and then gradually decreased toward the vesicoureteral junction (young: p < 0.05; middle-aged: p < 0.05; old: p > 0.05; males: p < 0.05; females: p < 0.05). Similar were the regional distributions of residual strain at the interface between epithelium-lamina propria and muscle and of internal but not external residual strain. Wall thickness increased steadily with aging ( p < 0.05 at few regions), while ureteral circumference did not ( p > 0.05 at most regions) and opening angle decreased ( p < 0.05 at several regions). Consistent with Fung's stress-growth law, the muscle layer thickened with age unlike the epithelium-lamina propria that thinned ( p < 0.05 at most regions for both thicknesses). Moderate-to-strong direct correlations of residual strain difference (= external - internal) with opening angle, wall thickness, and curvature were found in most ureters. The presented data will provide insight into the biomechanical response of ureter under zero/low-stress conditions and the relationship between ureteral remodeling and aging. Importantly, they may also be used to inform finite element models and computational studies simulating the ureter.