Stem Cells

Considerando a origem de obtenção, as células-tronco podem ser classificadas como células-tronco embrionárias (ES) ou como células-tronco adultas. Mas, se a plasticidade for considerada, as células-tronco podem ser classificadas como células totipotentes, quando as células-tronco preservam a capacidade de dar origem a um novo indivíduo completo. Quando as células-tronco perdem esta capacidade, passam a ser classificadas como células-tronco pluripotentes, que podem dar origem a praticamente todos os tipos celulares maduros que compõem um organismo. Células-tronco totipotentes e pluripotentes podem ser obtidas de estágios embrionários iniciais. O grupo de células-tronco que apresenta plasticidade restrita é denominado de multipotente. Estas células podem se diferenciar em determinado tipo celular comprometido com um órgão ou tecido específico. Células ES podem ser expandidas in vitro, mantendo sua forma indiferenciada, ou podem ser submetidas a uma série de protocolos, que irão induzir diferenciação in vitro. Por outro lado, as células-tronco adultas multipotentes não podem ser mantidas in vitro na forma indiferenciada, exceto uma subpopulação de células-tronco adultas aderentes, denominadas células-tronco mesenquimais, que podem ser mantidas in vitro na forma indiferenciada. Considerando a capacidade de gerar teratomas, as células ES não foram utilizadas para transplante celular experimental in vivo. Além disso, várias cirurgias de transplantes experimentais com células-tronco adultas têm sido realizadas, porém apresentando resultados controversos.Stem cells can be classified as embryonic stem (ES) cells or adult stem cells considering their origin. If plasticity is considered, stem cells can be classified as totipotent, when stem cells retain the ability to give rise to an entire new organism. When stem cells lose this capacity, cells are named pluripotent stem cells, which can give rise to almost all mature cell types that compound an organism. Totipotent and pluripotent stem cells can be obtained from developing early-stage embryos. Multipotent is the group of adult stem cells with restricted plasticity. These cells can differentiate into a defined cell type related with a specific organ or tissue. ES cells can be propagated in vitro under undifferentiated system or with a series of protocols to induce cell differentiation. On the other hand, multipotent adult stem cells cannot be maintained in vitro in an undifferentiated form, except for a special class of adherent adult stem cells named mesenchimal stem cells, which can be expanded in vitro conserving their undifferentiated characteristics. Considering the ability to gen-erate teratomas, ES cells were not used in experimental in vivo cell transplant. On the other hand, several experimental adult stem cells transplants have been performed with controversial results

Mouse embryonic stem cells: The establishment of the system to produce differentiated cell types in vitro

During the last few years, embryonic stem (ES) cells have been a new tool in cell biology which is very promising for the scientific community to develop new cell therapies. ES cells are the only cell type that can differentiate into derivates of the three primary germ layers, not only in vivo but also, and most important, in vitro. This so-called pluripotency has resulted in the field of stem cell technology going into overdrive, and the establishment of many protocols for optimal maintenance, culture, genetic transfection and in vitro differentiation. The first pluripotent cells had been derived from teratocarcinomas, maligne tumors, and showed some disadvantages. Therefore later embryonic stem cells, and now adult stem cells are getting special attention from the scientists. In this study, we established for the first time in our country, the prolonged culture of undifferentiated ES cells in vitro and the pointed induction of cell differentiation into specific cell types. It is the result of an international collaboration program supported by Brazil and Germany, CAPES and DAAD (PROBRAL). The well-established routine should be clearly demonstrated by the continuous culture and propagation of several mouse ES lines in vitro under specific culture conditions preventing differentiation. On the other hand, these ES cells were exposed to defined differentiation induction systems to obtain specialized cells as cardiogenic, neurogenic and myogenic cell types. This demonstrates the successful procedure to induce ES cell line differentiation. In this study, we established both routine systems, with and without differentiation. This results gave us competence and possibility to develop a series of different scientific approaches

Natural orifices transluminal endoscopic surgery (NOTES) : main access and implications : review

As cirurgias endoscópicas transluminais por orifícios naturais ou NOTES (Natural Orifice Transluminal Endoscopic Surgery) significam um novo conceito de cirurgia, uma vez que são produzidas pela hibridização de endoscopia e laparoscopia, culminando em uma modalidade cirúrgica com ausência de incisões abdominais. Diversas vias de acesso para a NOTES já foram descritas na literatura, entre elas: a via transvaginal, a transgástrica, a transuretral, a transcolônica e a transretal, sendo os acessos transvaginal e transgástrico os mais estudados até o momento. Apesar da NOTES apresentar vantagens como menor dor abdominal, rápida recuperação pós-operatória, menor risco de aderências e herniações, ausência de cicatriz e menor reposta inflamatória sistêmica, a necessidade de um fechamento seguro da víscera de acesso à cavidade abdominal, bem como adequada cicatrização do órgão ainda são desafios desta nova abordagem cirúrgica. Desta maneira, o presente trabalho tem por objetivo trazer uma revisão bibliográfica da cirurgia por orifícios naturais, como também suas implicações clínicas decorrentes dos diferentes acessos à cavidade abdominal.Natural orifices transluminal endoscopic surgery (NOTES) is a new concept in surgery produced from the hybridization of endoscopy and laparoscopy and results in incisionless to the abdominal cavity. Different routes for NOTES have been described in the literature among them, the transvaginal, the transgastric, transurethral, transcolonic and the transretal, but the transvaginal and trangastric access the most studied to date. Present advantages, such as lower abdominal pain, rapid postoperative recovery, less risk of adhesions and hernias, no scar and lower systemic inflammatory response, however the secure closure and cicatrization of the viscera are still challenges of this new surgical approach. This study aims to review of natural orifice surgery, as well as their clinical implications of different access to the abdominal cavity

Indução de diferenciação In Vitro de Células-Tronco Embrionárias em células de tecido cardíaco e nervoso

Embryonic stem cells are pluripotent cell lines with the capacity of self-renewal and a broad differentiation plasticity. They are isolated from preimplantation embryos and can be cultured in vitro for long time without losing their pluripotency. Embryonic stem cells can also differentiate in vitro with the proper combination of growth and differentiation factors, cells will differentiate into more advanced stages of embryogenesis generating different adult cell type. In the present study, we induced the in vitro differentiation of mouse embryonic stem cells (line R1) into cardiomyocytes and neuronal cells. These differentiations were evaluated by reverse transcription-polymerase chain reaction to verify presence of tissue-specific markers.Células-tronco embrionárias são linhagens celulares pluripotentes capazes de se multiplicar indefinidamente e com grande capacidade de diferenciação celular. São isoladas de embriões em estágio pré-implantacional e podem ser cultivadas por longo tempo em laboratório sem perder sua pluripotencialidade. Células-tronco embrionárias podem, ainda, se diferenciar in vitro através da adição de fatores de crescimento e diferenciação ao meio de cultivo. As células se diferenciarão em estágios mais avançados de embriogênese, gerando tipos diferentes de células adultas. No presente estudo, induzimos a diferenciação in vitro de células-tronco embrionárias de camundongos (linhagem R1) em células de tecido cardíaco e nervoso. A diferenciação foi avaliada pela reação em cadeia da polimerase precedida de transcrição reversa para verificar a presença de marcadores tecido-específicos

Liquid and Gel Platelet Rich Plasma as Skin Healing Adjuvant

Background: In recent decades, many researches have been conducted on processes involved in tissue repairing, mainly in the development of resources and technology designed to improve the wound healing progress. Platelet rich plasma (PRP) derived from autologous blood is defined as a plasma volume with platelet concentration higher than physiological level. It is an autogenous and low cost source of growth factors, which are essential for tissue regeneration due to their angiogenic, mitogenic, and chemotactic properties. The aim of this study was evaluate two forms of PRP- liquid and gel - regarding their capacity to influence quality and repair time of standardized skin injuries.Materials, Methods & Results: New Zealand healthy rabbits were distributed in three groups (n = 6): control group (CG), liquid platelet rich plasma group (LIQPRP), and gel platelet rich plasma group (GELPRP). Acute skin lesions were inducted in two areas approximately 2 cm close to scapular edge and depth including epidermis, dermis, and hypodermis to external muscular fascia. Animals received treatment according to each group. Injuries were measured with digital pachymeter in two directions: longer length (l) and longer width (w), every two days. Areas and healing rates were calculated. Microscopic analysis samples were collected on days seven and 14 and evaluated through hematoxylin and eosin staining (HE) for global tissue examination, and through Masson’s trichrome (MT) to collagen fibers present within the interstice. These analyzes considered: angiogenesis, inflammation infiltrated and collagen fibers quantity. Immunohistochemistry with anti-Ki-67 antibody was utilized for proliferative profile assessment. Kruskal-Wallis’ non-parametric tests of independent samples was performed for comparison of values obtained through platelet count, referring to evaluation of platelet increase on treatments. Scar contraction rate (CR) was evaluated through Shapiro-Wilk’s normality test, and then submitted to mixed models test. Results obtained by histopathological and immunohistochemistry were also evaluated by Shapiro-Wilk’s normality test (for all tests a 5% level of significance was considered). Platelet concentration achieved with liquid PRP was 8.64 and gel PRP reached 5.62 times higher than physiological values. Platelet increase mean for both groups was 7.95. No statistical significance was observed between groups. No side-effects or adverse reactions related to PRP usage were observed while study was conducted.Discussion: In the present study, there was a need to raise platelet poor plasma volume in order to obtain autogenous thrombin required for gel PRP. After this modification, a stable and reasonable platelet concentration gel was produced. However, this form of PRP application requires more time for sample preparation, increasing the production cost. Furthermore, injection of liquid PRP directly in the wound site activates platelets by generated substances due to needle perforation, and mainly due to tissue trauma generated at the lesion site. Relating to the therapies administered, gel PRP was considered more manageable, since 3D structure could easily adapt to wound site after simply deposition of it. Liquid PRP was administered with needle and syringe, which required the surgeon to be more careful and perform a slow injection in order to avoid any spill and loss of material. Furthermore, histopathological analysis did not point any clot traces formed by gel PRP dehydration, although it is not possible to ensure that the clot was eliminated, reabsorbed, or even removed by the animal. By this protocol, a stable and reasonable platelet concentration gel was produced. Further studies are encouraged as well as employment of alternative diagnostic tools, in order to better understand found results