Role of chemical groups in regulating membrane tension of mBMSCs under stretch stimulation

As a crucial mechanobiological regulator, the tension of the cell membrane plays a vital role in governing cellular adhesion, proliferation, and differentiation processes. Additionally, it displayed a dynamic response to mechanical microenvironmental changes. This research systematically examines the mechanoresponsive behaviors of mouse bone marrow mesenchymal stem cells (mBMSCs) that are cultured on poly(dimethylsiloxane) (PDMS) substrates which are functionalized with methyl (-CH₃), amino (-NH₂), and carboxyl (-COOH) groups. Under both static and stretching conditions, it is found that compared with the -CH₃ surface, static culture on the -NH₂ and -COOH functionalized surfaces significantly promotes the proliferation of mBMSCs and upregulates the expression of extracellular matrix adhesion-related genes, especially focal adhesion kinase (FAK) and integrin β1. Morphometric analysis reveals that there are concomitant increases in the cell spreading area and the number of pseudopods on these modified surfaces. Mechanical stretching stimulation not only amplifies these cellular responses but also leads to more uniform FAK distribution. The assessment by atomic force microscopy (AFM) shows that both chemical functionalization (-NH₂/-COOH) and stretch stimulation reduce the deformability of the cell membrane, and the -NH₂ modification exhibits a greater membrane-stiffening effect than -COOH.