Electrophysiological Analysis of Brain Organoids: Current Methods and Advances

Brain organoids, miniature three-dimensional structures derived from pluripotent stem cells, hold tremendous promise for modeling the complex architecture and functionality of the human brain in vitro. As researchers strive to enhance the fidelity of these models, electrophysiological techniques have emerged as indispensable tools for probing the electrical activity within organoids. While technologies such as single-cell sequencing have made significant advances in the characterization and understanding of brain organoids, improved functional analyses, particularly electrophysiology, are needed to realize the full potential of brain organoids.

Creative Biolabs discusses current electrophysiological approaches to brain organoid analysis and reviews advances in electrophysiological and analytical techniques applicable to brain organ analysis. We are one of the well-recognized experts who are professional in applying advanced platforms for a broad range of neuroscience research. Now we provide the novel STEMOD™ neuroscience ex vivo models and basic neuroscience assays and research tools for our clients all over the world.

The Emergence of Brain Organoids

The creation of brain organoids began with pioneering work in stem cell biology and developmental neuroscience. Stem cells have the unique ability to differentiate into a variety of cell types, providing the basis for generating complex multicellular structures in vitro. Based on this knowledge, researchers developed protocols to induce pluripotent stem cells to form neural progenitor cells.

Early attempts to grow neural tissue in three-dimensional cultures yielded basic structures similar to those of the developing brain. These first organoids lacked the complex tissue and cellular diversity found in vivo, but represented a major leap forward in modeling human brain development. As techniques for culturing and maturing organoids improved, researchers achieved greater complexity and functionality, ultimately producing brain organoids with different regions and cell types.

Electrophysiological Analysis of Brain Organoids

The hallmark of functional analysis of nerve cells and tissues, including brain organoids, is electrophysiology. The ability to record neuronal function is critical for many brain organoid applications, especially disease modeling and CNS drug discovery. Most conventional electrophysiology techniques have been applied to brain organoids and have unique advantages and disadvantages.

• Classical electrophysiologic methods such as patch clamp allow for high temporal resolution of brain organoid neural activity, but provide little spatial resolution for assessing whole-brain organoid activity.
• Calcium imaging provides activity information on a larger scale, but sacrifices temporal resolution and is dependent on imaging capacity.
• Microelectrode arrays (MEAs), which have been adopted in recent years, provide network scale and high temporal resolution, but currently lack the three-dimensionality required to properly analyze brain organoid activity.

Here, we directly compare the advantages and disadvantages of existing and new electrophysiological methods.

Recent Advances in Electrophysiology - Applicability to Brain Organoids

• A recently developed technique, called PatchSeq, combines patch-clamp electrophysiological recordings with sc-RNA-seq, allowing functional correlation with gene expression. Although still limited in size and throughput, correlation with genetic and morphological analyses provides a new dimension of functional analysis that may be useful in analyzing specific subsets of neurons in brain organoids.
• Recently, the development of all-optical electrophysiology has provided a method for manipulating and recording neural activity at high spatiotemporal resolution. This approach consists of co-transfecting neurons with channelrhodopsin (CheRiff) and spectrally orthogonal fluorescent genetically encoded voltage indicator (GEVI) allowing simultaneous recording of neural activity. The ability to stimulate and record simultaneously with this all-optical setup allows network-level recording of neural circuits while maintaining single-cell and high temporal resolution.
• Three-dimensional MEA (3DMEA) is currently under development. By integrating electrodes into flexible hinged probes, extracellular recordings can be obtained from 3D neural networks such as those found in organoids. These devices are compatible with many existing easily accessible recording setups, thus facilitating rapid adoption by brain organoid researchers.

Despite significant progress, a number of challenges remain in the field of brain organ electrophysiological analysis. Achieving higher spatial and temporal resolution, improved long-term stability and enhanced scalability are key areas for future research. In addition, the development of standardized protocols and benchmarking standards is critical to ensure reproducibility and comparability between studies.

Creative Biolabs is at the forefront of this endeavor, providing innovative solutions and expertise to advance the field. By capitalizing on the synergies between electrophysiology and brain organoid technology, we are poised to make revolutionary discoveries.

For Research Use Only. Not For Clinical Use.