The Influence of Astrocytes on Parkinson's Disease Cybrids

Astrocytes and the factors released from these cells have direct effect on neuronal health and its functions. In the present study we examined the influence, if any, of astrocytes on control cybrids or Parkinson’s disease (PD) cybrids, in relation to neuronal differentiation and mitochondrial functioning. Primary astrocytes were isolated from zero day old rat pups and cultured till they attain maturity, and used in co-culture with cybrids by means of contact co-culture, non-contact co-culture using transwell insert or culture with added astrocytes conditioned medium (ACM). We investigated cybrid’s multiplication, neurite outgrowth, expression levels of dopaminergic marker tyrosine Hydroxylase (TH), glial cell-line derived neurotrophic factor receptor GFRα1, its co-receptor c-RET and mitochondrial membrane depolarization after the co-culture. Noncontact co-culture caused an increase in neurite connections by enhancing the neurite outgrowth, neurite density, the number of neurons with neurites as well as cell number. Expression of TH was enhanced in all the groups except the insert group of PD cybrids. GFRα1 was increased in control cybrid of all the groups, whereas in case of PD cybrids no significant change in GFRα1 level was found other than the contact co-culture group. The increase in expression of these proteins in PD cybrids of contact co-culture group was accompanied with the significant enhancement in mitochondrial membrane potential compared to the untreated control and this effect of astrocytes on mitochondrial quality was absent in noncontact co-culture groups. These data support the notion that in vitro culture conditions that mimic natural brain environment are more realistic when neurons are cultured along with astrocytes. Moreover, control cybrids grown in presence of astrocytes exhibit less MPP+-induced cell death when compared to toxin-treated normal control cybrids. Therefore, such co-culture would be more relevant for experiments aimed to design diagnostic and therapeutic strategies for PD.