Up until now, how have scientists studied the behaviour of neurons in controllable environments?
A variety of methods are being utilized. These include 2D cell cultures, cells in hydrogels, tissue slices and organoids. In all cases these methods have benefits and limitations. To date, none of these methods have provided the level of physiological relevance that the new 3D brain-like cortical tissues demonstrate, including versatility to study cell responses and selection compartments, sustainable cultivation for the study of acute and chronic effects, a suitable in vitro model for traumatic brain injury (TBI), electrophysiological and biochemical responses and related needs.
What are the main restrictions of growing neurons in 2D?
In 2D, neurons tend to form limited connectivity reflective of the 3D complexity in the brain and have more limited cultivation time before reduction in functions. Also, cells are well documented to respond differently in a 3D environment (which represents the native state in the brain) vs. 2D.
What challenges have tissue engineers faced when attempting to grow neurons in 3D gel environments?
Gel environments are very suitable for many 3D neuron studies. However, the cultivation time is usually limited to a few weeks as the gels tend to contract and cells internal in the matrix become necrotic or change, while those on the periphery do well. Also, the gel approach does not allow compartmentalized approaches to permit the study of cell-niche control of physiology and functions, something that we see as very important.