Sorting neurons from preserved brain tissue

Neuroscientists routinely store brain tissue samples in brain banks for future analysis. Being able to use cell-sorting techniques such as flow cytometry on this preserved tissue would allow researchers to study the effects of drugs, environmental factors, and diseases on specific brain cell types. However, it’s difficult to separate cells from chemically fixed, frozen tissue samples and prepare them for flow cytometry without causing damage. Now, Charles D. Nichols of the Louisiana State University Health Sciences Center New Orleans and colleagues have developed new protocols to overcome these limitations (ACSChem. Neurosci. 2017, DOI: 10.1021/acschemneuro.6b00374). The researchers separated cells from human and rodent brain tissue samples—fixed using preservatives such as formalin, zinc, and paraformaldehyde—by passing liquefied frozen tissue through needles multiple times and applying an enzyme solution that cleaves chemical bonds between cells. They then fluorescently tagged the cells and passed cell suspensions through a flow cytometer to isolate two types of neurons. Importantly, the researchers were able to perform downstream genetic and biochemical analyses on these recovered cells, indicating the cells were undamaged.