The placenta is a temporal, dynamic and diverse organ with important immunological features that facilitate embryonic and fetal development and survival, notwithstanding the fact that several aspects of its formation and function closely resemble tumor progression. Placentation in mammals is commonly used to characterize the evolution of species, including insights into human evolution. Although most placentas are discarded after birth, they are a high-yield source for the isolation of stem/progenitor cells and are rich in extracellular matrix (ECM), representing an important resource for regenerative medicine purposes. Interactions among cells, ECM and bioactive molecules regulate tissue and organ generation and comprise the foundation of tissue engineering. In the present article, differences among several mammalian species regarding the placental types and classifications, phenotypes and potency of placenta-derived stem/progenitor cells, placental ECM components and current placental ECM applications were reviewed to highlight their potential clinical and biomedical relevance.
Biological biomaterials for tissue engineering purposes can be produced through tissue and/or organ decellularization. The remaining extracellular matrix (ECM) must be acellular and preserve its proteins and physical features. Placentas are organs of great interest because they are discarded after birth and present large amounts of ECM. Protocols for decellularization are tissue-specific and have not been established for canine placentas yet. This study aimed at analyzing a favorable method for decellularization of maternal and fetal portions of canine placentas. Canine placentas were subjected to ten preliminary tests to analyze the efficacy of parameters such as the type of detergents, freezing temperatures and perfusion. Two protocols were chosen for further analyses using histology, scanning electron microscopy, immunofluorescence and DNA quantification. Sodium dodecyl sulfate (SDS) was the most effective detergent for cell removal. Freezing placentas before decellularization required longer periods of incubation in different detergents. Both perfusion and immersion methods were capable of removing cells. Placentas decellularized using Protocol I (1% SDS, 5 mM EDTA, 50 mM TRIS, and 0.5% antibiotic) preserved the ECM structure better, but Protocol I was less efficient to remove cells and DNA content from the ECM than Protocol II (1% SDS, 5 mM EDTA, 0.05% trypsin, and 0.5% antibiotic).
Objective This study was aimed to provide a key update to the seminal works of Prof. Albert L. Rhoton Jr., MD, with particular attention to previously unpublished insights from the oral tradition of his fellows, recent technological advances including endoscopy, and high-dynamic range (HDR) photodocumentation, and, local improvements in technique, we have developed to optimize efficient neuroanatomic study. Methods Two formaldehyde-fixed cadaveric heads were injected with colored latex to demonstrate step-by-step specimen preparation for microscopic or endoscopic dissection. One formaldehyde-fixed brain was utilized to demonstrate optimal three-dimensional (3D) photodocumentation techniques. Results Key steps of specimen preparation include vessel cannulation and securing, serial tap water flushing, specimen drainage, vessel injection with optimized and color-augmented latex material, and storage in 70% ethanol. Optimizations for photodocumentation included the incorporation of dry black drop cloth and covering materials, an imaging-oriented approach to specimen positioning and illumination, and single-camera stereoscopic capture techniques, emphasizing the three-exposure-times-per-eye approach to generating images for HDR postprocessing. Recommended tools, materials, and technical nuances were emphasized throughout. Relative advantages and limitations of major 3D projection systems were comparatively assessed, with sensitivity to audience size and purpose specific recommendations. Conclusion We describe the first consolidated step-by-step approach to advanced neuroanatomy, including specimen preparation, dissection, and 3D photodocumentation, supplemented by previously unpublished insights from the Rhoton fellowship experience and lessons learned in our laboratories in the past years such that Prof. Rhoton's model can be realized, reproduced, and expanded upon in surgical neuroanatomy laboratories worldwide.
Objectives/Hypothesis: Releasing the nasoseptal flap (NSF) pedicle from the sphenopalatine artery (SPA) foramen may considerably improve flap reach and surface area. Our objectives were quantify increases in pedicle length and NSF reach through extended pedicle dissection into the pterygopalatine fossa (PPF) through cadaveric dissections and present clinical applications.Study Design: Anatomical study and retrospective clinical cohort study. Methods: Twelve cadaveric dissections were performed. Following standard NSF harvest, the distance from the anterior edge of the flap to the anterior nasal spine while pulling the flap anteriorly was measured. As dissection into the SPA foramen and PPF continued, similar interval measurements were completed in four stages after release from the SPA foramen, release of the internal maxillary artery (IMAX), and transection of the descending palatine artery (DPA). The extended pedicle dissection technique was performed in seven consecutive patients for a variety of different pathologies.Results: The mean length of the NSF from the anterior nasal spine and maximum flap reach were 1.91 AE 0.40 cm/9.3 AE 0.39 cm following standard harvest, 2.52 AE 0.61 cm/9.75AE1.06 cm following SPA foramen release, 4.93 AE 0.89 cm/12.16 AE 0.54 cm following full IMAX dissection, and 6.18 AE 0.68 cm/13.41 AE 0.75 cm following DPA transection. No flap dehiscence or necrosis was observed in all seven surgical patients.Conclusions: Extended pedicle dissection of the NSF to the SPA/IMAX markedly improves the potential length and reach of the flap. This technique may provide a feasible option for reconstruction of large anterior skull base and craniocervical junction defects. Seven successful cases are presented here, but further studies with larger series are warranted to validate findings in a clinical setting.
Volumetric muscle loss causes functional weakness and is often treated with muscle grafts or implant of biomaterials. Extracellular matrices, obtained through tissue decellularization, have been widely used as biological biomaterials in tissue engineering.Optimal decellularization method varies among tissues and have significant impact on the quality of the matrix. This study aimed at comparing the efficacy of four protocols, that varied according to the temperature of tissue storage and the sequence of chemical reagents, to decellularize murine skeletal muscles. Tibialis anterior muscles were harvested from rats and were frozen at -20°C or stored at room temperature, followed by decellularization in solutions containing EDTA + Tris, SDS and Triton X-100, applied in different sequences. Samples were analyzed for macroscopic aspects, cell removal, decrease of DNA content, preservation of proteins and three-dimensional structure of the matrices. Processing protocols that started with incubation in SDS solution optimized removal of cells and DNA content and preserved the matrix ultrastructure and composition, compared to those that were initiated with EDTA + Tris. Freezing the samples before decellularization favored cell removal, regardless of the sequence of chemical reagents. Thus, to freeze skeletal muscles and to start decellularization with 1% SDS solution showed the best results.
Although the sphenoidal emissary foramen (SEF) and its content are anatomically and clinically relevant, accurate description of them in the modern literature is lacking. This study aimed to examine and describe the SEF and its content (the sphenoidal emissary vein [SEV]). We analyzed 1,000 computed tomography (CT) images, 170 dry skulls, 50 formalin‐fixed specimens, and three specimens (heads) following guidelines proposed by Dr. Albert L. Rhoton Jr. MD for latex injection. SEV morphology was determined by histological staining and electron microscopy. The SEF was observed in 46.8% of the CTs studied (25.4% bilateral and 21.4% unilateral), and 45.2% of the dry skulls (18.8% bilateral and 26.4% unilateral). In 9.5% of CTs and 21.1% of dry skulls there was a blind channel in the external surface of the cranial base; since there was no communication with the cranial cavity, it was not considered as the SEF. During the dissections, the SEF was found in seven individuals. In three of them, the SEV was an alternative route for venous drainage of the venous plexus of the foramen ovale. Its walls were composed of collagen fibers and its endothelium contained rhomboid cells resembling those commonly found in the superior sagittal sinus. The presence of the SEF and SEV can anatomically explain the spread of certain cranial base pathologies from or toward Meckel's cave or the cavernous sinus, and should be taken into account during procedures in the middle cranial fossa, percutaneous approaches, odontological procedures, and treatment of dural arteriovenous fistulas. Clin. Anat., 33:767–781, 2020. © 2019 Wiley Periodicals, Inc.
Background: The pineal region and dorsal midbrain are among the most challenging surgical targets. To approach lesions in this region that harbor a superior to inferior long axis, we describe the basic steps of the precuneal, interhemispheric, trans-tentorial approach and illustrate anatomical landmarks of this established, but not so popular, surgical trajectory.Method: To study the anatomical landmarks and safety of this approach, the neurovascular anatomy was studied on 22 sides of 11 formalin-fixed latex-injected anatomical specimens. A step-by-step dissection of the precuneal interhemispheric trans-tentorial approach and study of the key anatomical landmarks was performed. An illustrative clinical case of a pontomesencephalic cavernous malformation (CM) resected through this approach is also detailed.Results: The mean distance from the transverse sinus to the most posterior cortical vein draining into the superior sagittal sinus was 6.4 cm. The mean distance from the calcarine sulcus to the most posterior cortical vein was 5.3 cm. Key steps of the dissection are as follows: craniotomy exposing the posterior aspect of the superior sagittal sinus (SSS), durotomy and gentle retraction of the SSS edge, dissection of the interhemispheric fissure, linear incision of the tentorium that extends anteriorly to the incisura and lateral reflection of the tentorium, and arachnoidal dissection and exposure of the cerebellomesencephalic fissure. Conclusion:The precuneal, interhemispheric, trans-tentorial approach affords excellent access to the falcotentorial junction, splenium, pineal region, quadrigeminal cistern, and dorsal pons once the cerebellomesencephalic fissure has been dissected.
LEONEL, L. C. P. C. Production and characterization of bioactive biomaterials obtained from decellularized placentas. [Produção e caracterização de biomateriais acelulares bioativos obtidos a partir da decelularização de placentas]. 2016. 117 f.
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