Scientists have developed a groundbreaking two-dimensional model to study neuromuscular diseases. This has enabled efficient drug testing and improved our understanding of diseases such as spinal muscular atrophy and amyotrophic lateral sclerosis.

Researchers have so far identified about 800 different neuromuscular diseases. These conditions are caused by problems with how muscle cells, motor neurons, and peripheral cells interact. These diseases, such as amyotrophic lateral sclerosis and spinal muscular atrophy, can cause muscle weakness, paralysis, and even death.

“These diseases are very complex and the causes of dysfunction are diverse,” said Dr. Mina Gouti, head of the Max Delbrück Center’s Developmental Stem Cell Modeling and Disease Laboratory. The problem could be in the neurons, the muscle cells, or the connections between the two. “To better understand the causes and find effective treatments, we need human-specific cell culture models that allow us to study how motor neurons in the spinal cord interact with muscle cells.”

Innovative research using organoids

Researchers working with Gouti had already developed a three-dimensional neuromuscular organoid (NMO) system. “One of our goals is to use our cultures for large-scale drug testing,” Gouti says. “Three-dimensional organoids are so large that they cannot be cultured for long periods of time in the 96-well culture dishes we use to conduct high-throughput drug screening studies.”

Human self-assembling 2D neuromuscular junction model. Immunofluorescence analysis of the whole dish shows myocytes (magenta) organized into bundles surrounded by spinal neurons (cyan). Credit: Alessia Urzi, Max Delbrück Center

For this type of screening, an international team led by Gouti has now developed a self-organizing neuromuscular junction model using pluripotent stem cells. The model includes neurons, muscle cells, and chemicals. synapse It is called the neuromuscular junction, which is necessary for two types of cells to interact. The researchers have now published their findings in the journal. nature communications.

“The 2D self-assembled neuromuscular junction model allows us to perform high-throughput drug screening for various neuromuscular diseases and study the most promising candidates in patient-specific organoids,” says Gouti. .

2D neuromuscular model development

To establish a 2D self-organizing neuromuscular junction model, the researchers first needed to understand how motor neurons and muscle cells develop in the embryo. Although Minas’ team does not conduct embryo research themselves, they use a variety of human stem cell lines and induced pluripotent stem cell lines (iPSCs), which are allowed for research purposes under strict guidelines.

“We tested several hypotheses. We found that the cell type required for functional neuromuscular connections is derived from neuromesodermal progenitor cells,” says doctoral student and author of the paper. says lead author Alessia Urzi.

Urji discovered the right combination of signaling molecules that allow human stem cells to mature into functional motor neurons and muscle cells, and the necessary connections between them. “It was very exciting to see muscle cells contracting under the microscope,” Urji says. “That was a clear sign that we were on the right path.”

Another observation was that upon differentiation, cells organized into regions containing muscle cells and nerve cells, rather like a mosaic.

Optogenetic advances in neuromuscular research

Myocytes grown in culture dishes contract spontaneously as a result of their connections with neurons, but without any meaningful rhythm. Urji and Guti wanted to solve it. In collaboration with researchers at the Charité University of Berlin, they used optogenetics to activate motor neurons. Neurons activated by the flash of light fire and contract muscle cells in synchrony, causing them to move in a way that mimics the physiological conditions of an organism.

Modeling and testing for spinal muscular atrophy

To test the effectiveness of the model, Professor Urji used human iPSCs taken from patients with spinal muscular atrophy. Spinal muscular atrophy is a serious neuromuscular disease that affects children during their first year of life. Neuromuscular cultures generated from patient-specific induced pluripotent stem cells showed severe problems with muscle contraction similar to the patient’s disease state.

For Gooty, 2D and 3D cultures are important tools to study neuromuscular diseases in more detail and test more efficient and personalized treatment options. As a next step, Gouti and her team hope to conduct high-throughput drug screens to identify new treatments for patients with spinal muscular atrophy and amyotrophic lateral sclerosis. “We want to start by using new drug combinations to see if we can achieve more successful outcomes to improve the lives of patients with complex neuromuscular diseases. ” says Gooty.

Reference: “Efficient Generation of Self-Assembling Neuromuscular Junction Models from Human Pluripotent Stem Cells,” Alessia Urzi et al., December 19, 2023. Nature Communications.
DOI: 10.1038/s41467-023-43781-3

Source: scitechdaily.com