The cybrid technique (adapted from Kish et al.). The procedure involves obtaining mtDNA from persons with and without disease. Usually, platelets are used as the mtDNA donor tissue, since platelets are easily obtained through standard phlebotomy, are easy to isolate through centrifugation and lack nuclei. Mixing platelets with cell lines depleted of their own endogenous mtDNA allows exchange of platelet and cell line materials, which results in cell lines containing mtDNA from the individual platelet donors. These cell lines expand under standard culture conditions, and their biochemical assessment allows investigators to evaluate parameters directly or indirectly referable to mitochondria and the mtDNA they carry. Differences in mtDNA lead to differences in the mtDNA-encoded subunits of oxidative phosphorylation complexes I, III, IV and V. Functional differences between cybrid cell lines should reflect differences in mtDNA that cause changes in these enzyme complexes.