The invention relates to a method of malting a non-human mammal model comprising: a. implanting, into an immunocompromised non-human mammal host, heterologous nucleated cells previously bound to a biocompatible support, b. controlling non-adaptive defences of the non-human mammal host, c. recovering a non-human mammal model harbouring settled heterologous nucleated cells capable of maintaining, differentiating and growing. The invention also relates to a non-human mammal model which is an immunocompromised non-human mammal host implanted with a support comprising heterologous nucleated cells settled thereon, and which non-adaptive defences are controlled to enable the heterologous nucleated cells of said implanted support to maintain, differentiate and grow.