Leibniz Institute for Polymer Research Dresden

In this study [1], ToF-SIMS was applied to detect subtle differences between human mesenchymal stromal cell (MSC)-secreted extracellular matrix (ECM) types as induced by exogenous stimulation or emerging pathology. Spectra measured for decellularized ECM samples were evaluated by discriminant principal component analysis (DPCA) to decipher characteristic compositional features. To establish the approach, signatures of the ECM proteins collagen I, fibronectin, and laminin-111 were determined and verified by the analysis of pre-defined mixtures. Based on that, sets of ECM variants produced by MSCs in vitro were analyzed. Differences in the content of collagens, fibronectin, and laminins in the ECM resulting from the combined supplementation of MSC cultures with polymers that induce macromolecular crowding and with ascorbic acid were detected from the DPCA of ToF-SIMS spectra and verified by immunostaining. Finally, the comparative ToF-SIMS analysis of ECM produced by MSCs of healthy donors and patients suffering from myelodysplastic syndrome (MDS) displayed the potential of the novel methodology to reveal disease-associated alterations of the ECM composition.

Workflow for the ToF-SIMS analysis of extracellular matrices. (A) MSC isolation and culture, followed by decellularization and desalting steps. (B) ToF-SIMS analysis of multiple replicates for each culture condition. (C) Scores and loadings of DPCA of the mass spectra collected for ECM samples from cultures with graded supplementation of ascorbic acid (ASC) and FiColl (FC) indicate ASC boosted collagen synthesis and elevated collagen, fibronectin, and laminin secretion under crowding conditions (supplement of FC). For details see Ref. [1].

Unravelling the complexity of biomatrices is a persisting challenge in many areas of the life sciences. The detection of soluble signaling molecules – cytokines and growth factors – within multicomponent biopolymer scaffolds is of particular interest as they control important biological processes such as the development of tissues, pathologies, and regeneration. In this study [2], we explored the application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for the detection of interleukin-8 (IL-8), a chemokine involved in inflammation and cancer, within biopolymer matrices of different complexity. To establish the workflow, IL-8 was embedded with graded mass fractions in thin biopolymer matrices consisting of heparin and/or bovine serum albumin, followed by a comprehensive ToF-SIMS analysis of the prepared samples. Partial least square regression (PLSR) models were developed and successfully applied to detect IL-8 mass fractions down to 1 ppm on the basis of the measured ToF-SIMS spectra. The methodology was successfully applied to detect IL-8 in MatrigelTM and poly(ethylene glycol)-heparin matrices with similar sensitivity. Given the high performance of state-of-the-art SIMS instruments and the increasing power of machine learning algorithms, we envision that the established approach, in combination with other methods, will enable a comprehensive assessment of soluble signalling molecules in (engineered) matrix-supported 3D cell and organoid cultures.

Workflow for the analysis of graded mass fractions of IL-8 in biopolymer matrices. (A) Embedding of IL-8 in biopolymer matrices of different complexity. (B) ToF-SIMS analysis of multiple samples. (C) Model optimization and deployment. For details see Ref. [2].

References:

[1] Zimmermann et al. Small Methods 2023, 2201157, doi: https://doi.org/10.1002/smtd.202201157

[2] Zimmermann et al. Adv. NanoBiomed Res. 2025, 2500066, doi: https://doi.org/10.1002/anbr.202500066