Neurosphere

[1] In 1992, Brent A. Reynolds and Samuel Weiss attempted to isolate EGF-responsive cells from an adult mouse central nervous system (CNS).

After more proliferation and longer days in vitro in the presence of EGF, cells eventually became immunoreactive to neurofilament, NSE, and GFAP.

Reynolds and Weiss found that, at 21 days, in vitro cultures of spheres and associated cells contained two of the major neurotransmitters of the adult striatum.

[1] Since the neurosphere assay's goal is to develop neural stem cells in vitro, the clinical applications of such an achievement can be highly beneficial.

Neural stem cells that are transplanted are able to cross the blood–brain barrier and integrate themselves into the host's brain without disrupting normal function.

This therapeutic application of neural stem cells derived from neurospheres is still in its infancy concerning efficacy, but it has a high potential for success in treating many diseases.

They concluded that adult NSCs were indeed able to survive and differentiate in the injured inner ear and that this type of therapy could act to restore auditory function in hearing-impaired subjects.

[7] However useful the neurosphere culture has been for biological studies of developmental processes and the functional assay for testing neuronal characteristics, there are several limitations to the method.

Another problem with the system arises from the nature of suspension cultures (in vitro) : individual cells cannot easily be carefully monitored.

Since the neuronic capacity of the neurosphere-expanded cells diminishes after an extended number of passages, the lack of monitoring adds further complexity to the neurosphere method.

Neural progenitor cells : After forming a neurosphere, embryonic neural progenitor cells spread out into a monolayer. A. Neurosphere consisting of SVZ cells isolated at E15 that have aggregated in suspension after 2 days in culture. Scale bar: 100 μm. B. Neurosphere of SVZ cells derived at E15 that has attached to the floor of the culture flask after 4 days in culture. Note cells migrate away from the neurosphere. Scale bar: 100 μm. C. Cells at the periphery of neurospheres were chosen for electrophysiological recording. Most of the recorded cells extended processes. Arrows indicate the location of recording (left) and puffer (right) pipettes. Scale bar: 20 μm. Smith DO et al., PLoS ONE , 2008
Neurospheres have been used to study viral susceptibility to zika virus infection. [ 4 ]