CONDITIONED MEDIUM FROM AGED MONKEY FIBROBLASTS STABLY EXPRESSING GDNF AND BDNF IMPROVES SURVIVAL OF EMBRYONIC DOPAMINE NEURONS IN-VITRO

Fibroblasts derived from the cerebral cortex of an aged Bonnet monkey (Macaca radiata) were utilized to express recombinant cDNAs encoding r at glial-cell-line-derived neurotrophic factor (GDNF) and human prepro brain-derived neurotrophic factor (BDNF) by lipofection. The cells sh owed stable expression and secretion of biologically active proteins. Conditioned medium from fibroblasts expressing BDNF or GDNF increased the number of surviving mesencephalic tyrosine-hydroxylase-immunoreact ive neurons after 7 days in culture. The trophic effects of BDNF and C DNF were examined at two different plating densities of embryonic mese ncephalic cells. At 50000 cells/cm(2) plating density, treatment of th e mesencephalic cultures with BDNF-conditioned medium increased the nu mber of tyrosine-hydroxylase-immunoreactive neurons by about 40% compa red with vector-transfected control. At the same plating density, GDNF -conditioned medium increased the number of surviving tyrosine-hydroxy lase-immunoreactive neurons above the vector-transfected control by 30 %. When the tissue was plated at a higher density, viz., 75000 cells/c m(2), the number of tyrosine-hydroxylase-immunoreactive neurons increa sed by 41% with BDNF-conditioned medium, and by 56% with GDNF-conditio ned medium above vector-transfected controls. Conditioned medium from cells secreting GDNF was also found to reduce the number of apoptotic tyrosine-hydroxylase-immunoreactive cells by 50%.