The New Scientist reports on another step forward for medical engineering: "a 'bioscaffold' made of collagen impregnated with stromal and dendritic cells extracted from the thymus of newborn mice [was] then implanted into mice with healthy immune systems that had been vaccinated against a harmless antigen (something that triggers an immune response). ... After the artificial node had filled with antigen-specific T and B cells, Watanabe transplanted it into a mouse with no functioning immune system. The lymphocytes quickly spread out from the artificial node into the animals' own lymph nodes ... After a month, these cells' 'memory' was still maintained, and they were able to fight off challenges from the antigen. ... The next step is to use human cells in humanised mice. Then, maybe in four or five years, we might be able to make the first prototypes of a human model ... By implanting artificial nodes plump with healthy T and B cells in AIDS patients, he believes he might be able to revitalise their damaged immune systems. For cancer, he hopes to adopt a similar approach in which the transplanted nodes will contain T cells trained to hunt down the antigens produced by tumour cells and kill them off."