multicellular spheres in vitro 19. These neurospheres have self-renewal ability, can be
cultured over 10 passages, and can be easily maintained and expanded without losing
the expression of neural progenitor markers 18,20
.
Neurospheres have the potential to generate sub-type or region-specific neurons (22).
However, their tendency to clump in culture makes them very difficult to study and to
identify the types of neurons that can be derived after neurosphere transplantation 18,20
.
It is also difficult to precisely monitor the morphology of single neurons from
neurosphere-derived neuronal aggregates. Moreover, generating sub-type-specific or
region-specific functional neurons from h/iPSCs takes more than 6-8 weeks with the
traditional neuronal generation protocols 11,21,22
. Here, we present novel culture
conditions and methods to rapidly and efficiently generate functional human sub-type or
region-specific neurons from neurospheres. This method involves a combination of
supplemented knockout serum replacement medium (SKSRM) with 10% CO2 and a
mechanical procedure termed “AdSTEP,” which involves breaking the neurospheres
into smaller fragments to increase the efficiency of neuronal production. Furthermore,
we injected the fragmented neurospheres into the severe combined immunodeficiency
(SCID) mouse brains to investigate the effect of AdSTEP on neurogenesis in vivo,
which might have significant impacts on neuronal transplantation and regenerative
medicine.
Materials and Methods
Maintenance of the H9 lines and generation of the human induced pluripotent
stem cell (iPSC) line HFS-1