Reconstruction of parietal bone defects with adiposederived mesenchymal stem cells: experimental study

Purpose: This study assessed the regeneration potential of mesenchymal stem cells (MSC) from adipose tissue associated with platelet-rich plasma (PRP) in bone regeneration. Methods: Thirty Wistar rats (Rattus norvegicus albinos) were divided into five groups (according to the grafting material and time to euthanasia): (1) autograft - 14 days (control), (2) autograft - 28 days (control), (3) MSC + PRP - 14 days, (4) MSC + PRP + papaverine - 14 days and (5) MSC + PRP + papaverine - 28 days. After euthanasia, the graft was removed and histological slides were prepared. They were assessed by a blinded pathologist using a previously published histological scale as parameter. Results: There was some degree of neoformed bone trabeculae (NBT) in 93.3% of the samples, as well as osteoblastic activity (OA). The autograft groups (14 and 28 days) had higher levels in the formation of bone trabeculae. Nonparametric data were analyzed using the Wilcoxon-Mann-Whitney test and proved not to be statistically significant at p 0.05. Conclusions: Experimental parietal bone reconstruction, combining MSC, PRP and papaverine presented regeneration in all groups with no significant difference among them.(AU)

Characterization of acute murine dextran sodium sulfate (DSS) colitis: severity of inflammation is dependent on the DSS molecular weight and concentration

Background: Colitis murine models have become essential tools to investigate the molecular and cellular mechanisms that lead to infl ammatory bowel disease (IBD), such as ulcerative colitis (UC). DSS-induced colitis model faithfully reproduces many of the clinical presentation and immunological disturbances observed in UC. Notwithstanding mice can show differential susceptibilities and responsiveness to dextran sodium sulfate (DSS), and varying DSS concentration and molecular weights appear to be associated with the severity of inflammation. The aim of this study was to analyze the features of mice induced colitis using different DSS concentrations and molecular weights. Materials, Methods and Results: C57BL/6 mice received 2% of high molecular weight DSS (36 000 - 50 000) in drinking water (HDSS2%) or 5% of the same molecular weight (HDSS5%); other group received 5% of low molecular weight DSS (10 000) (LDSS5%). During the 7 days of DSS administration, animals were observed for weight loss, stool consistency and presence of blood feces to determine the disease activity index (DAI). On day 8, colons were removed, measured and weighed for indirect assessment of infl ammation. The tissue samples were processed for histological analysis and blood samples were collected for hematological analysis. Our results demonstrated that HDSS5% group began to show significant clinical signs starting from day 1, HDSS2% on day 2 and LDSS5% on day 3 (P < 0.05). However, from day 3, HDSS5% group presented DAI significantly higher than other groups (P < 0.001). In addition, DSS administration for 7 days was associated with significant (P < 0.05) changes in mice body weight compared to control animals. Group HDSS2% showed a weight loss of 23.8%±3.0, and HDSS5% and LDSS5% groups, presented weight loss of 32.65%±0.0 and 8.7%±1.7, respectively. From day 6, HDSS5% group presented weight loss significantly greater than HDSS2% and LDSS5% groups (P < 0.05). In colon macroscopic analysis, high molecular weight DSS groups showed a significantly macroscopic colon changes (P = 0.001) and hematological parameters alteration (P < 0.005) compared to control group. In histological features of colitis, these groups presented a higher histological score compared to normal colon (P < 0.001), with crypt damage, mucosal ulceration and cell inflammatory infiltration. Mice from group LDSS5% did not present significant macroscopic colon changes, hematological parameters alteration, and histological score compared to control group. Discussion: Results of the present study evidenced that acute colonic mucosal injury induced by DSS is dependent on the concentration and molecular weight of DSS administered in drinking water, and these findings are important consideration for reproducible induction of experimental colitis with this model. Moreover, DSS with high molecular weight and high concentration can initiate a severe colitis, which may not be an appropriate model for studies of therapeutic regeneration of the colonic mucosa. Thus, identification of differences in mice response to DSS could provide the basis for investigations of susceptibility or resistance to colitis. DSS-induced colitis model study contributes to the understanding of IBD and in the finding for new therapies targeting the reduction of inflammation.

Comparação entre três protocolos de obtenção de plasma rico em plaquetas (PRP) utilizando o coelho como modelo experimental / Comparison of Three Protocols to Obtain Platelet Rich Plasma (PRP) with Rabbits as Experimental Model

Background: Platelet rich plasma (PRP) is a blood-derived source of growth factors and several cytokines, which are essential for tissue regeneration and important for wound healing due to their angiogenic, mitogenic, and chemotactic activities. To date no protocol has been established for PRP production. Standardization of this technique should consider fundamental factors such as experimental model used, blood collection method, anticoagulant choice, rotation and amount of centrifugations, elapsed time between sample activation and its clinical use in order to ensure quality and biological effects of the product. This study aimed to compare three protocols for PRP achievement in order to evaluate platelet enrichment ability and method reproducibility for further use in clinical investigations regarding PRP therapeutic properties. Materials, Methods & Results: New Zealand higid rabbit's whole blood was collected in tubes containing sodium citrate. Samples were obtained through exsanguination, via abdominal aortic puncture, and separated in four aliquots designed for PRP processing and basal platelet count. The count was conducted at the time blood was collected and after every concentration protocol. Methods were tested in triplicates, and three different individuals repeated each technique for three times, reaching 27 repetitions. Selected methodologies consisted in two centrifugations protocols: protocol A used 250 g for 10 min for the first separation, and another 10 min at 2000 g during the second centrifugation; protocol B proposed that first centrifugation would last 20 min at 160 g, and the second would last 15 min at 400 g, and protocol C consisted of 10 min at 400 g for the first separation, and 10 min at 800 g during second separation. Protocols were performed at the same time in three similar centrifuges, in order to standardize the variables (operator, time, environment, equipments), and also to diminish biases. Comparison objects in this study include: ability of raising platelet concentration, time required for preparing the final product, reproduction handiness, and need for equipment for proper hemoconcentrated production. Achieved platelet count in each protocol and basal value were analyzed following randomized complete. Kurskal-Wallis test was used for independent samples comparison, considering a 5% significance level. For each tested sample, elapsed time for product preparation was evaluated. Subjective analyzes comprehended execution easiness and the need for special material, and were evaluated through questionnaire after each protocol. Protocol A showed a 25-fold increase in platelet count, whereas protocols B and C had 13 and 7-fold, respectively. Results indicate all protocols were efficient in concentrating the samples at least 3 times more than basal count. Elapsed time for product preparation in each protocol was 35, 52, and 41 min for A, B, and C methods, respectively. Subjective analyzes considered protocols A and C as low complexity, and protocol B was defined as medium complexity in regards to execution. With reference to material accessibility for protocols, all were considered of easy reproducibility. Discussion: Besides analyzing experimental model and most proper way to access blood collection, this study was limited to verify in a quantitative manner the platelet concentration in specific protocols, without evaluating their biological effects. Therefore, in regards to proposed objectives - relation between platelet concentration increase, spent time, and easiness of protocol - we conclude that protocol A, formulated by Nagae et al. (2007), was the method that most fitted the work needs, and greatly suited the challenges posed.

Estabelecimento da técnica de indução da diferenciação celular in vitro de células tronco embrionárias de camundongos em células cardíacas e células nervosas

Células tronco são células que possuem a capacidade de originar diferentes tipos celulares maduros. Podem ser classificadas como células tronco embrionárias (células ES), quando isoladas de embriões em estágios iniciais do desenvolvimento; ou como células tronco adultas, quando isoladas de diferentes tecidos de indivíduos adultos. Por outro lado, as células tronco podem ser classificadas conforme o seu potencial de diferenciação celular. Assim, podem ser denominadas como totipotentes, isoladas do embrião, quando este possui até oito células. Células tronco totipotentes possuem a capacidade de gerar todos os tipos celulares oriundos dos três folhetos embrionários, e também podem dar origem aos tecidos formadores dos anexos embrionários. Somente as células totipotentes possuem esta capacidade, e por isso, somente estas, podem gerar um novo indivíduo completo. As células tronco pluripotentes, isoladas de blastocistos ou de carcinomas embrionários, possuem a capacidade de se diferenciar em todos os cerca de 200 tipos de tecidos especializados, que compõem o indivíduo adulto. Contudo, vale ressaltar que as células tronco pluripotentes jamais poderão originar um novo indivíduo. Por fim, existe ainda a classificação de células tronco multipotentes, que possuem a característica de gerar alguns tipos celulares e apresentam uma menor capacidade de multiplicação in vitro, quando comparadas com os outros tipos de células tronco. Estas células podem ser encontradas em diferentes órgãos de indivíduos adultos, como por exemplo, medula óssea, sangue de cordão umbilical, cérebro, fígado e outros. No presente trabalho, visamos o estabelecimento da rotina de manutenção de células tronco embrionárias de camundongo in vitro. Sob a forma indiferenciada e no sistema de indução de diferenciação celular. Para tanto, utilizamos a linhagem de células tronco embrionárias de camundongos, denominada R1. Seguindo protocolos específicos, direcionamos o processo de diferenciação celular para a geração majoritária de células cardíacas e nervosas. Os resultados da diferenciação celular das células tronco embrionárias de camundongos foram analisados a partir da morfologia celular e através da utilização de técnicas de biologia molecular. A obtenção de culturas de células tronco embrionárias enriquecidas em células cardíacas e nervosas comprovou, através do presente trabalho, que os objetivos propostos foram atingidos. Tendo sido estabelecidas, como rotina, em nossa Universidade, as técnicas de cultivo de células ES em estado indiferenciado, e através do método de indução de diferenciação celular in vitro para células cardíacas e nervosas. Os resultados obtidos confirmam os dados descritos na literatura, o que indica que a técnica foi implantada de forma adequada. Assim, adquirimos o domínio das técnicas necessárias para a utilização das ES in vitro como uma nova ferramenta de trabalho podendo ser utilizada em diferentes projetos de pesquisa

Stem cells are able to originate different cell types. Stem cells can be classified as embryonic stem cells (ES cells) wich can be isolated from pre-implantation embryos; or as adult stem cells wich can be obtained from different adult tissues. On the other hand, stem cells can be classified considering their ability to differentiate into different cell types. Firstly, stem cells can be named as totipotent when isolated from 8 cell stage embryos. Totipotent stem cells are capable to differentiate into all cell types from the three germ layers. Additionally, the totipotent cells can generate the embryonic acessories. This characteristic promotes this cell type as the only cell group able to generate an entire individual. Pluripotent stem cells, isolated from the blastocyst or from embryonic carcinoma (EC), presents the capacity to generate all the 200 cell types that compound the adult individual. It is important to note that the pluripotent stem cells cannot generate a new complete individual. Finally, there is the multipotent stem cells, which can generate some cell types and presents a reduced ability to replicate in vitro when compared with another stem cell types. Multipotent stem cells can be isolated from different adults tissues and organs, for example, bone marrow, umbilical blood cord, brain, liver and others. In the present experiment, we established the routine of in vitro mice embryonic cell culture techniques. On the undifferentiated and into differentiation system. For that we worked with R1 mice stem cell line. Based on described protocols for induction of differentiation system direct to cardiogenesis and neurogenesis. The obtained results from the induction of differentiation were detected by morphological and molecular analyses. The goals of the present study can be verified by the establishment of the ES cell culture system and with the obtained ES culture cells enriched with cardiac and neuronal cells. In this way, we can notice the establishment of the ES cells described techniques by our research group in our University. Our results confirm the described literature data ensuring the well establishment of the ES cell culture system. With this work we acquire the ability to perform in vitro experiments with mice embryonic stem cells, so our group can use these cells as a new research toll which can be applied in different science projects