Developing a practical guide for teaching histology: an evaluation of the didactic components

The Didactic Guide is a valuable tool complementing and making learning more dynamic. It is done using creative didactic strategies that simulate the presence of the tutor and generate a dialogue in order to offer students different possibilities to improve their understanding and self-discovery learning.This way the student is the protagonist of his own learning process. In this context, is highly important to consider the self discovery learning as a goal facilitating significant learning. The use of practical guides enables students to manage their own time, goals, techniques, contents and evaluation. In medical histology teaching several models of didactic guides could be use, and they normally include numerous activities, text, questionnaires, pictures, and drawings that may enhance the effectiveness of this tool in the learning process. In this work we have evaluated the usefulnes of different sections of a histology didactic guide in order to determine the key sections that enhance the learning process in human histology. For this purpose, a practical histology guide was designed with different sections: message text, theoretical text, objectives, drawings, pictures, clinical cases, games, blank spaces for self notes and drawing and final self evaluation questions. First, a simple questionnaire was applied in 90 students enrolled in histology practical seccions to analyze the student´s perceptions and preferences related to the histology guide. Finally, for all questionnaires average results and standard deviations were calculated for each option and all participants, as well for each gender, separately. Comparisons were done for drawings vs drawing blank spaces, teoric content vs notes blank space, drawings vs pictures and for each gender separately using Mann-Whitney non-parametrical test. Our findings revealed that visual strategies such as images and pictures were considered to be more useful for learning histology in the practical session. Similary, the students rated the self evaluation questions and blank spaces for self notes and drawing to be more attractive to the students. However, texts with theoretical information, messages, objectives, and clinical cases revealed to be less useful for the students in the learning process of medical histology. Moreover, statistically significant differences between theoretical content vs notes blank space was observed. All these results point out the importance of including pictures and drawings in the practical guide accompained of blank spaces that allow the development of creativity and autonomy that lead the students into a self discovery learning. Interestingly the students do not appreciate the presence of theoretical background in the practical guide as relevant information for their academic formation in the practical session

New teaching era for histology: from glass slides to virtual microscope as an alternative for selfdiscovery learning

Medical histology is a basic science that deals with concepts and facts regarding the microscopic structure of the human body. Histology has traditionally been taught as a lecture and microscopybased practical course using glass slides and microscopes and it is based on reception learning. However, a new era has been implemented using virtual microscope in order to improve the selfdiscovery learning process. Self-discovery learning is a constructive learning method that takes place without systematic external guidance and differs from tutorization and continuous instructions of reception learning method. The use of virtual microscope implies autonomous exploration of the histological images by simply dragging the mouse and changing the file of interest accompanied by the observation at different magnifications with a click. This method increases discussion and collaboration while increasing the speed and efficiency of learning without the need of light microscope. Virtual microscope encourages active learning environment and also places the students at the forefront of their own learning process being an useful tool for self- discovery learning. The knowledge about the students’ perceptions and their preferences is necessary for better design of self-discovery strategies in medical histology. In this study we have investigated male and female student´s preferences for optical (OM) and virtual microscope (VM) in a medical histology practical course. To achieve this, 90 first year medical students enrolled in medical histology course were evaluated. All students received 10 practical histology units (20 hours) where 5 (10 hours) units were taught using OM and 5 units (10 hours) with VM. Each student received both methods during the practical course. Each student completed a questionnaire after the whole practical units were performed in order to evaluate the student´s perceptions and preferences. The questionnaire consisted on four questions regarding OM and four questions related to VM the students have to answer to each question using a Likert scale from 1 to 5. Finally, a statistical test was use to analyze the results on the students perception´s and preferences for OM vs VM. Our results showed that both, OM and VM are adequate for histology learning as revealed by the high scores obtained for both types of methods. OM and VM tools were easy to manage and facilite the localization of histological structures during the visualization for all the students. However, most of the students significantly prefer to use VM to study the histological components of human tissues. The gender analysis revealed differences being statistically significant for men vs women for VM. These results suggest that VM should be included as an important tool for teaching human histology due to promote the self-discovery learning by the students

Evaluation of the cell viability of human Wharton's jelly stem cells for use in cell therapy

Human umbilical cord Wharton's jelly stem cells (HWJSCs) are gaining attention as a possible clinical source of mesenchymal stem cells for cell therapy and tissue engineering due to their high accessibility, expansion potential, and plasticity. We employed a combination of highly sensitive techniques to determine the average cell viability levels and proliferation capabilities of 10 consecutive cell passages of cultured HWJSCs and then used RNA microarrays to identify genes associated with changes in cell viability levels. We found an initial decrease in cell viability from the first to the third cell passage followed by an increase until the sixth passage and a final decrease from the sixth to tenth cell passages. The highest cell viability levels corresponded to the fifth and sixth passages. The intracellular ionic contents of potassium, sodium, and chlorine suggest that the lower cell viability levels at passages 2, 3, and 8-10 may be associated with apoptotic cell death. In fact, gene expression analysis revealed that the average cell viability was significantly associated with genes with a function in apoptotic cell death, especially pro-apoptotic FASTKD2, BNIP3L genes and anti-apoptotic TNFAIP8 and BCL2L2 genes. This correlation with both pro-apoptotic and anti-apoptotic genes suggests that there may be a complex live-death equilibrium in cultured HWJSCs kept in culture for multiple cell passages. In this study, the highest cell viability levels corresponded to the fifth and sixth HWJSC passages, suggesting that these passages should be preferentially employed in cell therapy or tissue engineering protocols using this cell type

Preclinical evaluation of bio-artificial conduits developed by tissue engineering for peripheral nerve regeneration

Peripheral nerves are histologically complex and delicate organs that form an organized network through the body. Histologically, peripheral nerves are composed of a nerve tissue or parenchyma and a variable amount of connective tissue or stroma. The parenchyma is composed of conductive units called peripheral nerve fibers, which are myelinated or unmyelinated. The stroma is composed by three layers, the epineurium, the perineurium and the endoneurium. Peripheral nerves are responsible to establish specific motor, sensory and autonomic pathways between the central nervous system and peripheral targets. Unfortunately, their function could be affected by different pathological conditions, and there is a high incidence of traumatic injuries that could result in physical and psychological consequences for these patients. Currently, nerve transections are generally subjected to direct surgical repair with acceptable recovery. For the case of critical nerve defects, they are bridged by using grafts and conduits obtaining variable results. Nerve autograft is the gold standard technique for critical nerve defects. In the case of conduits, they are relatively efficient in the treatment of short and non-critical nerve defects and currently it is still necessary to find an efficient alternative to the use of nerve autograft in the treatment of critical nerve defects. In this regard, the general aim of this Doctoral Thesis was to generate by tissue engineering three novel 3D bio-artificial tissue-like substitutes by using fibrin-agarose hydrogels (FAH) and adipose-derived mesenchymal stem cells (ADMSCs). For the first and second engineered bio-artificial nerve substitutes, acellular FAH or FAH containing ADMSCs were used as intraluminal fillers of collagen conduits and used to repair 10 mm nerve gap in rats. Furthermore, the regeneration and functional recovery was evaluated by clinical, functional and histological techniques. In the case of the third engineered bio-artificial substitute, a nanostructured FAH bio-artificial substituted was generated and characterized in vitro by using ultrastructural, biomechanical and histological techniques. The in vivo studies revealed that the use of FAH and FAH containing ADMSCs as intraluminal fillers of collagen conduits improved the peripheral nerve regeneration profile as compared to the use of hollow conduits (controls). Clinical and functional analyses revealed that these novel strategies induced a significant reduction of neurotrophic ulcers, neurogenic muscle retraction, and superior values for pinch test of sensory recovery, toe-spread and electromyography. Histological analyses showed a significant enhance of the peripheral nerve regeneration, especially when FAH containing ADMSCs was used. The analysis of the growth associating protein 43 (GAP-43) and neurofilament revealed that both axonal markers were differentially expressed during peripheral nerve regeneration, and both proteins were significantly increased by the use of FAH and specially FAH containing cells. The in vitro studies demonstrated that it is possible to generate biomimetic and biomechanically stable bio-artificial substitutes for peripheral nerve repair by combining nanostructured FAH and human ADMSCs. Biomechanical test revealed that the nanostructuration technique significantly improves the biomechanical and structural properties of these substitutes. Histological analyses showed that the mesenchymal stem cells were able to proliferate, form cell clusters and synthetize different kind of extracellular matrix molecules over the time. Finally, the experimental results obtained in this Doctoral Thesis, demonstrated that it is possible to improve the peripheral nerve regeneration by the incorporation of FAH into collagen conduits and, even more significant results can be obtained by the use of FAH containing ADMSCs. On the other hand, in vitro studies demonstrated that it is possible to generate 3D biomimetic and biologically active nanostructured FAH bio-artificial substituted for peripheral nerve repair by using nanostructured FAH and human ADMSCs. Finally, all these results confirm the suitability of FAH in peripheral nerve repair, especially when it is combined with ADMSCs