Saúde - Células de defesa geneticamente modificadas eliminam leucemia
Autor: Moacir Poconé | Publicado: 2011-08-18T06:48:00-03:00

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Células de defesa geneticamente modificadas eliminam leucemia
HIV foi usado para transportar material genético para os linfócitos T.Tratamento inédito funcionou melhor do que os cientistas esperavam.  
Do G1, em São Paulo   
O HIV pode se tornar o mais novo aliado da medicina na luta contra o câncer. Uma versão inerte do vírus da Aids foi usada com sucesso por cientistas norte-americanos para modificar geneticamente células de defesa do organismo e tratar pacientes com leucemia. O procedimento foi descrito nesta semana pelas revistas médicas New England Journal of Medicine e Science Translational Medicine.
  O tratamento inédito consiste em retirar os linfócitos T – importantes agentes de defesa do corpo – e transferir novos genes para elas. A mudança as torna capazes de destruir as células cancerosas que causam a leucemia e, assim, fazem com que o tratamento tenha sucesso.  
A transferência de genes para a célula é feita normalmente por um vírus, e é nessa fase que o HIV é usado; foi com ele que os pesquisadores da Universidade da Pensilvânia conseguiram modificar geneticamente as células de defesa.  
“Dentro de três semanas, os tumores tinham sido destruídos de um modo muito mais violento do que poderíamos esperar”, reconheceu Carl June, que conduziu a pesquisa. “Funcionou muito melhor que imaginávamos”.  
“Além de terem uma grande capacidade de se reproduzirem, as células T infundidas são ‘serial killers’. Em média cada uma levou à morte de milhares de células do tumor e, ao todo, destruíram pelo menos cerca de 1 kg em cada paciente”, completou o pesquisador.  
A nova técnica foi aplicada em três pacientes com leucemia linfoide crônica que já não tinham muitas opções de tratamento. Sem ela, eles seriam submetidos ao transplante de medula óssea, no qual o risco de morte é de pelo menos 20% e a chance de cura não supera os 50%.  
Agora, a equipe planeja usar o mesmo procedimento em tumores parecidos, como o linfoma não Hodgkin e a leucemia linfoide aguda. Eles também querem experimentar o tratamento em crianças que não reagiram bem ao tratamento convencional. No futuro, a ideia é adaptar a técnica para combater cânceres no ovário e no pâncreas.