We are interested in crosstalk between contracting muscle and the adipocytes that form between muscle fibers in injury and disease called intramuscular adipose tissue, or IMAT. Genetic engineering in cells in mice is a powerful tool for mechanistically dissecting fat muscle crosstalk. Analysis of signaling via transcriptomics and proteomics identifies mediators, and then biomaterial based drug delivery can intervene in these pathways.

One of the primary challenges is isolating and quantifying IMAT adipocytes. Especially in small animal models, the IMAT signal is washed out by whole muscle analysis like transcriptomics or lipidomics, and quantifying IMAT by noninvasive imaging suffers from similar washout, as most voxels contain a mixture of muscle and IMAT. We recently used this technique described in this article to demonstrate that IMAT directly impairs muscle contractility.

With precise measures of IMAT deposition, we showed that it does not just replace contractile material, but impedes a contraction in the remaining lean muscle. This protocol addresses challenges with quantifying IMAT. The current standard to measure IMAT in small animals is single section histology, which is not comprehensive or non-invasive imaging, which is expensive and low resolution.

We believe this has limited our understanding of IMAT muscle crosstalk. This technique provides a comprehensive and inexpensive method for assessing IMAT by qualitative visualization and multi-scale quantification. We hope this technique's simplicity will encourage more investigators to measure IMAT in their animal models.

Also, this technique will provide a higher precision tool for the investigators interested in IMAT to uncover more subtle relationships between IMAT adipocytes and other cells.