Figure 1

PCA and DA of young, old and OA cartilage. A) The spectra of all the old and OA samples after MALDI-MSI experiments were analyzed by PCA and DA to classify peptides specific of each category using a 1 D plot. B) Loading plot of DF1 representing the peptides specific to OA given by MALDI-MSI. The young specific peak 2415.9 is ringed. Figure C and D. PCA and DA separated the dataset on age of the sample. C) The spectra of all the young and old samples after MALDI-MSI experiments were analyzed by PCA and DA to classify peptides specific to each age using a 1 D plot. D) Loading plot of DF1 representing the peptides specific to age of cartilage given by MALDI-MSI. The young specific peak m/z 2414.9 is ringed. DA, discriminant analysis; MALDI, matrix assisted desorption ionization; MSI, mass spectrometry imaging; OA, osteoarthritis; PCA, principal component analysis.