Disclosure of a mammalian cytoplasmic donor cell line. Disclosure of a patient specific cell line. Disclosure of a method to obtain a mammalian cytoplasmic donor cell line by fusing a differentiated mammalian cell and a functionally enucleated mammalian embryonic cell line. Disclosure of a method to obtain a patient specific cell line of a cell type similar to a mammalian cytoplasmic donor cell line by functionally enucleating the mammalian cytoplasmic donor cell line and fusing the functionally enucleated mammalian cytoplasmic donor cell line with a differentiated cell obtained from the patient. A method of treatment administering the patient-specific cell line to the patient.