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Células estaminais - Portugal na vanguarda


A investigação com células estaminais em Portugal está entre as mais avançadas do mundo, nomeadamente em engenharia de tecidos e medicina regenerativa. “Estamos bastante à frente na expansão celular, temos um trabalho de muita qualidade na regeneração de osso, cartilagem e pele, por exemplo, e há muito trabalho ligado às células estaminais em neurociências.” Disse à Agência Lusa Luís Reis, presidente da Sociedade Portuguesa de Células Estaminais e Terapia Celular.


As células estaminais são divididas em dois grupos:

Embrionárias – são encontradas no embrião humano e são classificadas como totipotentes ou pluripotentes.

Adultas – são encontradas em diversos tecidos, como a medula óssea, sangue, fígado, placenta e cordão umbilical, entre outros. Estudos recentes mostram que estas células estaminais têm uma limitação na sua capacidade de diferenciação, o que limita a sua aplicação por parte dos especialistas.


Cada célula estaminal enquadra-se num dos seguintes grupos:

Células totipotentes – células capazes de originar qualquer célula embrionária e extra embrionária.

Células pluripotentes – células que podem produzir todos os tipos celulares do embrião excepto a placenta e os anexos.

Células oligopotentes – células com a capacidade de produzirem células de uma única linhagem celular (ex: linhagem de revestimento).

Células multipotentes – células que podem originar células de várias linhagens celulares.

Células unipotentes – células capazes de produzir apenas um tipo celular adulto.


No caso das células estaminais que se encontram no sangue do cordão umbilical, o seu isolamento e criopreservação (preservação utilizando baixas temperaturas) proporciona aos recém-nascidos e aos seus familiares a sua eventual utilização no tratamento de doenças que venham a contrair ao longo da vida. Numa das cinco empresas portuguesas dedicadas à criopreservação das células estaminais do cordão umbilical são já quase 25 mil os pais que decidiram guardar as células dos filhos por 20 anos, um serviço pelo qual pagam actualmente 1200 euros. A abertura recente no Avepark, nas Taipas (Guimarães), da sede do novo Instituto Europeu de Excelência em Engenharia de Tecidos e Medicina Regenerativa, de que é também director Luís Reis, é uma evidência do avanço científico existente em Portugal nesta área; segundo o próprio: “Fomos seleccionados por todos os outros membros do Instituto para assumirmos essa liderança, com critérios científicos, por sermos os mais produtivos e activos nessa área, e temos já pessoas de 25 países a trabalhar nele.”



Leis existentes em alguns países relativamente às células estaminais:

África do Sul - Permite todas as pesquisas com embriões, inclusive a clonagem terapêutica. É o único país africano com legislação a respeito.

Alemanha - Permite a pesquisa com linhagens de células estaminais existentes e a sua importação, mas proíbe a destruição de embriões.

Brasil - Permite a utilização de células estaminais produzidas a partir de embriões humanos para fins de pesquisa e terapia, desde que sejam embriões inviáveis ou estejam congelados há mais de três anos. Em todos os casos, é necessário o consentimento dos pais. A comercialização do material biológico é crime.

China, Singapura, Coreia do Sul, Israel, Japão e Rússia - Permitem todas as pesquisas com embriões, inclusive a clonagem terapêutica.

Estados Unidos - Proíbe a aplicação de verbas do governo federal a qualquer pesquisa envolvendo embriões humanos (a excepção é feita para 19 linhagens de células estaminais provenientes antes da aprovação da lei norte-americana). Contudo, estados como a Califórnia permitem e patrocinam esse tipo de pesquisa, inclusive a clonagem terapêutica.

França - Não tem legislação específica, mas permite a pesquisa com linhagens existentes de células estaminais embrionárias e com embriões de exclusão.

Índia - Proíbe a clonagem terapêutica, mas permite as outras pesquisas.

Itália - Proíbe totalmente qualquer tipo de pesquisa com células estaminais embrionárias humanas e sua importação.

México - Único país latino-americano, além do Brasil que possui uma lei que premite o uso de embriões. A lei mexicana é mais liberal que a brasileira, já que permite a criação de embriões para pesquisa.

Reino Unido - Tem uma das legislações mais liberais do mundo e permite a clonagem terapêutica.

Turquia - Permite pesquisas e uso de embriões de descarte, mas proíbe a clonagem terapêutica.

Posted by Immuniselectrun at 11:11

Hall of fame

Louis Pasteur

Birthday date: 27th December, 1822

The truth is surprising: as young, Louis Pasteur was a lazy student. His teachers never thought he was quite clever, as ahead he would show.

He studied physics and chemistry in Paris and chemistry was even the discipline in which we got a lower grade. Despite of that, later, He became a wise teacher and was one of the bigger scientists of ever, a genius of science. Only through one huge thirst of knowledge and an inexhaustible will of work the immortality was conquered and the death was defeated.

Facing all the expectations, the success arrived much early. With twenty six years he discovered the secret of crystals and a few time later he realized that the air we breathe it’s full of very small beings, He called them the invisible giants. Perhaps Pasteur already knew that these beings, apparently armless, were responsible for much part of the diseases shown in living beings. For sure he knew that the microorganisms used to enter in our organism with the purpose of unleash diseases. It was not easy to prove such theory in a time when all scientists thought that microorganisms were fruit of our own organism and not from outside. He wouldn’t give up anyway, He even bottled air to prove it, under the laugh of his colleagues , of course they didn’t even guess that what he was doing would become indispensable to his theory: none living being, including microorganisms, can appear in the world without descend from at least other of the same specie. In the course of his experiences, Pasteur could show up that microorganisms live in the air and reproduce themselves, entering in our body when they “feel” we are weakened and is the best shot to take. This was a very important discovery but his greatest feat, vaccine, would take more time to be created.

Before it, he helped the French farmers, solving a big problem: the quick sourness of wine. He observed microscopically the wine and found some kind of very short vegetation, called yeasts. Therefore, the yeasts were spoiling the wine, making it vinegary. Pasteur understood that wasn’t possible to take out those little creatures, they had to be killed and the only possible way: heat them up. The problem lied in the fact that the wine couldn’t heat up to high temperatures because it would change its quality. Persistent, Pasteur made a lot of experiences and found the solution: it was only necessary rise the wine’s temperature about sixty degrees centigrade to kill the microorganisms. These experiences gave rise to a much known process called pasteurization.

Pasteur was, undoubtedly, a chemistry genius and started to be called to solve the riddles that more nobody could. There was even a time when he was asked to find the origin of a plague which was killing thousands of silkworms. Pasteur, after some research, figured out that the butterfly was transmitting to her own eggs the disease and hence died so many of them. It was necessary to exterminate all larvae, butterflies and eggs which weren’t healthy. He had saved the French Industry of Silk and now, he’s stories of success were told not only in France but also abroad.

Modest, simple and not vain, Pasteur used to say that he only worked to help mankind. But, the fact of two of his sons have died with typhoid fever explain the dedication to Medicine and to studies about diseases caused by microorganisms.

Carbuncle was one of the first diseases studied by Pasteur. In that time, were dying many animals, mostly sheep due this disease. He discovered the responsible microorganism and made an experience: vaccinated twenty five sheep with the germ which caused the disease and left other twenty five sheep for vaccinate. Then he infected them all with the microorganism which made they feel sick. Happened that all vaccinated sheep survived and the others died. This was the first success of vaccination. However, he refused money to patent the medicine.

He wondered if would be worthwhile try to apply the same principles in the cure of human diseases. About 1880 Pasteur started to study the rage disease (affect animals, especially dogs, and normally is transmitted to humans by a nibble). Firstly, he discovered the rage virus. Then he used its “good” part to create an antidote and transformed it into a vaccine. Later, He started to inoculate it in the dogs but he didn’t have the courage to do the same in humans, until when on 6th July, 1885, a woman knocked on his door. She was carrying a boy with nine years old that was bitten by a dog fourteen times. The mother begged him to heal her son but the scientist didn’t want to experiment the serum in the kid named Joseph Meister because so far he never had used the vaccine in humans. However, once there was no other solution, eventually the kid would die with or without the inoculation, he applied the first of twelve anti-rage vaccines. During many weeks, the scientist and boy’s family feared the worst but in the end, Joseph Meister survived. From that time, people that had been bitten by raged dogs started to go to his laboratory asking for help. They came from different places of France and even from abroad although doctors didn’t recognize the worthwhile of Pasteur, what’s unthinkable, even because before his investigations, the only medicine available against rage was a spike in hot coal to burn the dog’s bite.

The vaccines were a huge triumph to medicine. Without them it’s difficult even think in survival.

Pasteur Institute:

The success of anti-rage vaccine was so enormous that the French Academy of Sciences decided to build one Institution dedicated only to laboratorial investigation. The Pasteur Institute was established in 1888 and is nowadays one of the most known centers of scientific investigation.

Curiosity – The HIV virus was isolated for the first time in these laboratories. This Institution without profitable ends was presided by Louis Pasteur until his death (28th September, 1895) and has a team of scientists that globally has eight Nobel Prizes in Medicine.

Microscope:

Nobody knows for sure who created it. Generally, its invention is attributed to Hans Janssen, Dutch glasses manufacturer, and his son Zacarias, in the year of 1590. However, will have been the Dutch Anton van Leeuwenhoek, that lived between 1632 and 1723, who made the first microscopic observations. He was a textile trader that used to mount lends. It was precisely through curved glasses that he mounted in a rudimental microscope that he saw little creatures which were walking along the drops of rain, vinegar and saliva. He was not a scientist but woke up the interest of scientific community. The first microscope had only one lend and so it couldn´t amplify very much.