The present invention relates to a method of producing expandable cultured brain cells. The brain cells are neurotrophic factor (NTF) positive. The expandable cultured brain cells are obtained by culturing a biopsy obtained from the cortical and/or subcortical brain region of a living subject. The biopsies can be obtained during neurosurgical procedures such as deep brain stimulation. The expandable cultured brain cells of the present invention are useful for the treatment of neurological diseases and other medical conditions.
