Functional and Sustainable 3D Human Neural Network Models from Pluripotent Stem Cells

Three-dimensional
(3D) in vitro cell and tissue
culture models, particularly for the central nervous system, allow
for the exploration of mechanisms of organ development, cellular interactions,
and disease progression within defined environments. Here, we describe
the development and characterization of human 3D tissue models that
promote the differentiation and long-term survival of functional neural
networks. This work builds upon previous work where primary rodent
neurons were successfully grown in a similar 3D system. The model was adapted to human induced pluripotent
stem cells, allowing for a more direct exploration of the human condition.
These tissue cultures show diverse cell populations, including neurons
and astroglial cells, interacting in 3D and exhibit spontaneous neural
activity confirmed through electrophysiological recordings and calcium
imaging over at least nine months. This approach allows for the direct
integration of pluripotent stem cells into the 3D construct, bypassing
early neural differentiation steps (embryoid bodies and neural rosettes).
The streamlined process, in combination with the longevity of the
cultures, provides a system that can be manipulated to support a variety
of experimental applications, including the study of network development,
maturation, plasticity, and/or degeneration. This tissue model was
tested with stem cells derived from healthy individuals as well as
Alzheimer’s and Parkinson’s disease patients. We observed
similar growth and gene expression, which indicates the feasibility
of generating patient-derived brain tissue models. These could be
used to uncover early stage biomarkers of the disease state, in turn
supporting earlier diagnosis and improving understanding of disease
progression. With additional model development, this approach would
have potential use for investigating drug targets in neurodegenerative
diseases.