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The loss of proteostasis, which results in the accumulation of misfolded proteins, is one of the hallmarks of aging and is frequently associated with the aging process. Fibroblasts are a cellular model widely used in the study of aging and can mimic the loss of proteostasis that occurs in the human body. When studying human aging using fibroblasts, two approaches can be used: fibroblasts from the same donor aged in vitro until senescence or fibroblasts from donors of different ages. A previous study by our group showed that the first approach can be used in the study of aging. Thus, this work aimed to study the spectroscopic profile of human dermal fibroblasts from four donors of different ages using Fourier-transform infrared spectroscopy to identify changes in protein conformation and to compare results with those obtained in the previous study. Partial least squares regression analysis and peak intensity analysis suggested that fibroblasts from older donors were characterized by an increase in the levels of antiparallel β-sheets and a decrease in intermolecular β-sheets, in agreement with our previous results.

Studying aging is important to further understand the molecular mechanisms underlying this physiological process and, ideally, to identify a panel of aging biomarkers. Animals, in particular mice, are often used in aging studies, since they mimic important features of human aging, age quickly, and are easy to manipulate. The present work describes the use of Fourier Transform Infrared (FTIR) spectroscopy to identify an age-related spectroscopic profile of the cardiac and skeletal muscle tissues of C57BL/6J female mice. We acquired ATR-FTIR spectra of cardiac and skeletal muscle at four different ages: 6, 12, 17 and 24 months (10 samples at each age) and analyzed the data using multivariate statistical tools (PCA and PLS) and peak intensity analyses. The results suggest deep changes in protein secondary structure in 24-month-old mice compared to both tissues in 6-month-old mice. Oligomeric structures decreased with age in both tissues, while intermolecular β-sheet structures increased with aging in cardiac muscle but not in skeletal muscle. Despite FTIR spectroscopy being unable to identify the proteins responsible for these conformational changes, this study gives insights into the potential of FTIR to monitor the aging process and identify an age-specific spectroscopic signature.