Characterization of Seeding Conditions for Studies on Differentiation Patterns of Subventricular Zone Derived Neurospheres

Stem cell research depends on extensive in vitro research. Poly-D-lysine (PDL) and polyornithine (PornT) are chemically synthesized amino acid chains promoting cell adhesion to solid substrates. Although, PDL and PornT are extensively used, there is no common agreement regarding the most optimal substance and its concentration. We therefore aimed at testing the effect of increasing concentrations (10, 50, and 100 μg/ml) for each compound and their corresponding mixtures (5+5 and 10+10 μg/ml) on the differentiation patterns of subventricular zone derived neurospheres. The latter were cultured for 24 h for protein and morphological analysis or for 8 h for migration analysis. No significant differences were found between increasing concentrations of PDL and PornT alone and the 10+10 condition in Western blots and immunocytochemistry. However, the mixed condition of 5+5 showed decreased glial fibrillary acidic protein and nestin expression with no changes in Akt, pAkt, GSK-3-beta, and pGSK-3-beta expression patterns. The various coating conditions also had no influence on migration of cells emerging from the neurosphere. Nevertheless, stimulation with recombinant human Erythropoietin (rhEpo) reduced migration by 20% regardless of the coating condition. We therefore conclude that a minimal concentration of 10 μg/ml of either compound should be used to produce reliable results with no alterations in protein levels as found for the 5+5 groups, and that the coating has no effect on the response of cells to chemical interventions. As such, a concentration of 10 μg/ml for either substance is sufficient when studying cellular processes of neurospheres in an in vitro or ex vivo environment.

An in vitro comparison of two different subpopulations of retinal progenitor cells for self-renewal and multipotentiality

Retinal progenitor cells (RPCs) show enormous potential for the treatment of retinal degenerative diseases. It is well known that in vitro cultures of RPCs comprise suspension spheres and adherent cells, but the differences between the two cell populations are not fully understood. In this study, cultured RPCs were sorted into suspension and adherent cells. Analyses of cell morphology, cell growth and retinal progenitor-related expression markers were performed using quantitative polymerase chain reaction (qPCR) and immunocytochemistry to identify the proliferative and multipotent capacity of the cells in vitro. The data showed that both the suspension and adherent cells were maintained in an undifferentiated state, although the former exhibited a greater proliferative potential than the latter. Immunocytochemistry analysis indicated that the two subsets of RPCs were able to differentiate into different retinal cells in the presence of fetal bovine serum (FBS); the adherent cells were more likely to differentiate toward the β3-tubulin-, AP2α- and Map2-positive neuronal lineage, while the suspension cells were more effective at differentiating into rod photoreceptors, which was consistent with the qPCR results. These findings suggest that adherent RPCs may be a potential candidate for retinal interneuron or ganglion cell substitution therapies, whereas suspension RPCs may be preferred for photoreceptor cell replacement.