Abstract
Purpose: :
To investigate possible differences in phenotypic and behavioral characteristics between adult neural progenitor cells maintained as free-floating, proliferating cellular aggregates (neurospheres) versus their counterparts that were maintained as an adherent, monolayer population; in vitro and after transplantation into the developing retina.
Methods: :
Differences in phenotypic and behavioral characteristics of adult hippocampal progenitor cells (AHPCs, from F. Gage, Salk Institute, La Jolla, CA) were compared by immunocytochemical techniques and time-lapse imaging. To examine the plasticity of AHPCs from both populations in the developing retina we transplanted the GFP-expressing AHPCs via intraocular injection into the eyes of postnatal day 1 Fischer 344 rats. Cell survival, morphological differentiation and integration were examined at 7, 14 and 28 days after transplantation.
Results: :
In vitro analyses demonstrated that both AHPC populations retained multipotency. AHPCs maintained as neurospheres favored differentiation along a glial lineage and displayed greater migrational activity, compared to the adherent population. At each time point examined, similar numbers of transplanted cells were observed in the cryo-sectioned eyes that received either AHPC neurospheres or adherent AHPCs. At later time points, considerably more cells were found integrated into the retina, often with highly branched processes. These findings demonstrate that both AHPC populations (neurosphere vs. adherent) were capable of surviving and integrating into the developing host retina.
Conclusions: :
The results suggest that cell-cell interactions during AHPC maintenance (as neurospheres) influenced cell fate under differentiation conditions. Moreover, transplanted neural progenitors displayed considerable plasticity of survival, differentiation, and integration in the developing host retina.
Keywords: transplantation • retina