Miguel-Ángel Martín-Piedra

Motivational component profiles in university students learning histology: a comparative study between genders and different health science curricula

BackgroundThe students’ motivation to learn basic sciences in health science curricula is poorly understood. The purpose of this study was to investigate the influence of different components of motivation (intrinsic motivation, self-determination, self-efficacy and extrinsic -career and grade- motivation) on learning human histology in health science curricula and their relationship with the final performance of the students in histology.MethodsGlynn Science Motivation Questionnaire II was used to compare students’ motivation components to learn histology in 367 first-year male and female undergraduate students enrolled in medical, dentistry and pharmacy degree programs.ResultsFor intrinsic motivation, career motivation and self-efficacy, the highest values corresponded to medical students, whereas dentistry students showed the highest values for self-determination and grade motivation. Genders differences were found for career motivation in medicine, self-efficacy in dentistry, and intrinsic motivation, self-determination and grade motivation in pharmacy. Career motivation and self-efficacy components correlated with final performance in histology of the students corresponding to the three curricula.ConclusionsOur results show that the overall motivational profile for learning histology differs among medical, dentistry and pharmacy students. This finding is potentially useful to foster their learning process, because if they are metacognitively aware of their motivation they will be better equipped to self-regulate their science-learning behavior in histology. This information could be useful for instructors and education policy makers to enhance curricula not only on the cognitive component of learning but also to integrate students’ levels and types of motivation into the processes of planning, delivery and evaluation of medical education.

Expression of epithelial markers by human umbilical cord stem cells. A topographical analysis

INTRODUCTION Human umbilical cord stem cells have inherent differentiation capabilities and potential usefulness in regenerative medicine. However, the epithelial differentiation capability and the heterogeneity of these cells have not been fully explored to the date. METHODS We analyzed the expression of several undifferentiation and epithelial markers in cells located in situ in different zones of the umbilical cord -in situ analysis- and in primary ex vivo cell cultures of Whartons jelly stem cells by microarray and immunofluorescence. RESULTS Our results demonstrated that umbilical cord cells were heterogeneous and had intrinsic capability to express in situ stem cell markers, CD90 and CD105 and the epithelial markers cytokeratins 3, 4, 7, 8, 12, 13, 19, desmoplakin and zonula occludens 1 as determined by microarray and immunofluorescence, and most of these markers remained expressed after transferring the cells from the in situ to the ex vivo cell culture conditions. However, important differences were detected among some cell types in the umbilical cord, with subvascular zone cells showing less expression of stem cell markers and cells in Whartons jelly and the amnioblastic zones showing the highest expression of stem cells and epithelial markers. CONCLUSIONS These results suggest that umbilical cord mesenchymal cells have intrinsic potential to express relevant epithelial markers, and support the idea that they could be used as alternative cell sources for epithelial tissue engineering.

Usefulness of a bioengineered oral mucosa model for preventing palate bone alterations in rabbits with a mucoperiostial defect.

The use of mucoperiostial flaps during cleft palate surgery is associated with altered palatal bone growth and development. We analyzed the potential usefulness of a bioengineered oral mucosa in an in vivo model of cleft palate. First, a 4 mm palate defect was created in one side of the palate oral mucosa of 3 week-old New Zealand rabbits, and a complete autologous bioengineered oral mucosa (BOM) or acellular fibrin-agarose scaffold (AS) was implanted. No material was implanted in the negative controls (NC), and positive controls were not subjected to palatal defect (PC). Animals were allowed to grow for 6 months and the results were analyzed morphologically (palate mucosa and bone size) and histologically. Results show that palatal mucosa and bone growth and development were significantly altered in NC and AS animals, whereas BOM animals had similar results to PC and the bioengineered oral mucosa was properly integrated in the host palate. The amount and compaction of collagen fibers was similar between BOM and PC, and both groups of animals had comparable contents of proteoglycans and glycoproteins at the palate bone. No differences were found for decorin, osteocalcin and BMP2. The use of bioengineered oral mucosa substitutes is able to improve palate growth and maturation by preventing the alterations found in animals with denuded palate bone. These results support the potential clinical usefulness of BOM substitutes for the treatment of patients with cleft palate and other conditions in which palate mucosa grafts are necessary with consequent bone denudation.

Identification of histological patterns in clinically affected and unaffected palm regions in dupuytren's disease.

Dupuytrens disease is a fibro-proliferative disease characterized by a disorder of the extracellular matrix (ECM) and high myofibroblast proliferation. However, studies failed to determine if the whole palm fascia is affected by the disease. The objective of this study was to analyze several components of the extracellular matrix of three types of tissues—Dupuytrens diseased contracture cords (DDC), palmar fascia clinically unaffected by Dupuytrens disease contracture (NPF), and normal forehand fascia (NFF). Histological analysis, quantification of cells recultured from each type of tissue, mRNA microarrays and immunohistochemistry for smooth muscle actin (SMA), fibrillar ECM components and non-fibrillar ECM components were carried out. The results showed that DDC samples had abundant fibrosis with reticular fibers and few elastic fibers, high cell proliferation and myofibroblasts, laminin and glycoproteins, whereas NFF did not show any of these findings. Interestingly, NPF tissues had more cells showing myofibroblasts differentiation and more collagen and reticular fibers, laminin and glycoproteins than NFF, although at lower level than DDC, with similar elastic fibers than DDC. Immunohistochemical expression of decorin was high in DDC, whereas versican was highly expressed NFF, with no differences for aggrecan. Cluster analysis revealed that the global expression profile of NPF was very similar to DDC, and reculturing methods showed that cells corresponding to DDC tissues proliferated more actively than NPF, and NPF more actively than NFF. All these results suggest that NPF tissues may be affected, and that a modification of the therapeutic approach used for the treatment of Dupuytrens disease should be considered.

Evaluation of freeze-drying and cryopreservation protocols for long-term storage of biomaterials based on decellularized intestine: EVALUATION OF FREEZE-DRYING AND CRYOPRESERVATION

We evaluated the efficiency of several protocols to preserve the main components of decellularized tissue scaffolds for delayed use. Decellularized rat intestine scaffolds were generated by using SDS and triton X-100 and preserved for 3 months subjected to eight freeze-drying (F1 to F8) and 14 cryopreservation protocols (C1 to C14). Morphological analysis showed that cryopreservation tended to preserve the tissue morphostructure more efficiently than freeze-drying. Histological analysis showed that the content of proteoglycans and glycoproteins was efficiently preserved by most methods. The protocols that most efficiently preserved collagen fibers were those using trehalose and saccharose for freeze-drying (F2, F3, and F7 protocols) and DMSO, albumin, and saccharose (C3, C5, C6, C12) for cryopreservation. Most freeze-drying protocols and cryopreservation protocols with DMSO, albumin, and maltose (C6, C7, C13, and C14) efficiently preserved reticular fibers. For the elastic fibers, freeze-drying methods with trehalose and maltose (F2, F4, F6, and F8) properly preserved these fibers, with the results of most cryopreservation methods comparable to controls. These results suggest that freeze-drying using 0.1M trehalose and cryopreservation in the presence of 8% DMSO and 4.6% albumin are more efficient than other protocols in preserving the scaffold morphostructure and histological composition.

Generation of a bioengineered autologous bone substitute for palate repair: an in vivo study in laboratory animals

We carried out an in vivo study to evaluate the potential usefulness of a novel bioengineered bone substitute for the repair of palate defects in laboratory rabbits, using tissue‐engineering methods. Our results showed that the use of a bioengineered bone substitute was associated with more symmetrical palate growth as compared to the controls, and the length and height of the palate were very similar on both sides of the palate, with differences from negative controls 4 months after artificial bone grafting for bone length. The histological analysis revealed that the regenerated bone was well organized and expressed osteocalcin. In contrast, bone corresponding to control animals without tissue grafting was immature, with areas of osteoid tissue and remodelling, as determined by MMP‐14 expression. These results suggest that bone substitutes may be a useful strategy to induce the formation of a well‐structured palate bone, which could prevent the growth alterations found in cleft palate patients. This opens a door to a future clinical application of these bone substitutes. Copyright

Development of a multilayered palate substitute in rabbits: a histochemical ex vivo and in vivo analysis

Current tissue engineering technology focuses on developing simple tissues, whereas multilayered structures comprising several tissue types have rarely been described. We developed a highly biomimetic multilayered palate substitute with bone and oral mucosa tissues using rabbit cells and biomaterials subjected to nanotechnological techniques based on plastic compression. This novel palate substitute was autologously grafted in vivo, and histological and histochemical analyses were used to evaluate biointegration, cell function, and cell differentiation in the multilayered palate substitute. The three-dimensional structure of the multilayered palate substitute was histologically similar to control tissues, but the ex vivo level of cell and tissue differentiation were low as determined by the absence of epithelial differentiation although cytokeratins 4 and 13 were expressed. In vivo grafting was associated with greater cell differentiation, epithelial stratification, and maturation, but the expression of cytokeratins 4, 13, 5, and 19 at did not reach control tissue levels. Histochemical analysis of the oral mucosa stroma and bone detected weak signals for proteoglycans, elastic and collagen fibers, mineralization deposits and osteocalcin in the multilayered palate substitute cultured ex vivo. However, in vivo grafting was able to induce cell and tissue differentiation, although the expression levels of these components were always significantly lower than those found in controls, except for collagen in the bone layer. These results suggest that generation of a full-thickness multilayered palate substitute is achievable and that tissues become partially differentiated upon in vivo grafting.

Effects of four formulations of prostaglandin analogs on eye surface cells : a comparative study

We evaluated the cytotoxic effects of four prostaglandin analogs (PGAs) used to treat glaucoma. First we established primary cultures of conjunctival stromal cells from healthy donors. Then cell cultures were incubated with different concentrations (0, 0.1, 1, 5, 25, 50 and 100%) of commercial formulations of bimatoprost, tafluprost, travoprost and latanoprost for increasing periods (5 and 30 min, 1 h, 6 h and 24 h) and cell survival was assessed with three different methods: WST-1, MTT and calcein/AM-ethidium homodimer-1 assays. Our results showed that all PGAs were associated with a certain level of cell damage, which correlated significantly with the concentration of PGA used, and to a lesser extent with culture time. Tafluprost tended to be less toxic than bimatoprost, travoprost and latanoprost after all culture periods. The results for WST-1, MTT and calcein/AM-ethidium homodimer-1 correlated closely. When the average lethal dose 50 was calculated, we found that the most cytotoxic drug was latanoprost, whereas tafluprost was the most sparing of the ocular surface in vitro. These results indicate the need to design novel PGAs with high effectiveness but free from the cytotoxic effects that we found, or at least to obtain drugs that are functional at low dosages. The fact that the commercial formulation of tafluprost used in this work was preservative-free may support the current tendency to eliminate preservatives from eye drops for clinical use.

Bioactive injectable aggregates with nanofibrous microspheres and human dental pulp stem cells: A translational strategy in dental endodontics

Regeneration of the pulp–dentin complex with stem cells is a potential alternative to conventional root canal treatments. Human dental pulp stem cells (hDPSCs) have been extensively studied because of their ability to proliferate and differentiate into mineralized dental and non‐dental tissues. Here we combined hDPSCs with two types of injectable poly‐l‐lactic acid (PLLA) microsphere with a nanofibrous or smooth surface to form bioactive injectable aggregates, and examined their ability to promote pulp regeneration in the root canal in an in vivo model. We investigated the biocompatibility, biosafety and odontogenic potential of fibrous (F‐BIM) and smooth bioactive injectable microspheres (S‐BIM) in vitro and in vivo. Our results demonstrated that PLLA microspheres and hDPSCs were able to form bioactive injectable aggregates that promoted dentin regeneration in both in vitro and in vivo models. Our results suggest that F‐BIM and S‐BIM may induce dentinogenesis upon in vivo grafting, and propose that the potential usefulness of the microsphere–hDPSC aggregates described here should be evaluated in clinical settings. Copyright