The Structural Interactions of Molecular and Fibrillar Collagen Type I with Fibronectin and Its Role in the Regulation of Mesenchymal Stem Cell Morphology and Functional Activity.

The observed differences in the structure of native tissue and tissue formed in vitro cause the loss of functional activity of cells cultured in vitro. The lack of fundamental knowledge about the protein mechanism interactions limits the ability to effectively create in vitro native tissue. Collagen is able to spontaneously assemble into fibrils in vitro, but in vivo, other proteins, for example fibronectin, have a noticeable effect on this process. The molecular or fibrillar structure of collagen plays an equally important role. Therefore, we studied the interaction of the molecular and fibrillar structure of collagen with fibronectin. Atomic force and transmission electron microscopy showed that the presence of fibronectin does not affect the native structure and diameter of collagen fibrils. Confocal microscopy demonstrated that the collagen structure affects the cell morphology. Cells are better spread on molecular collagen compared with cells cultured on fibrillar collagen. Fibronectin promotes the formation of a large number of focal contacts, while in combination with collagen of both forms, its effect is leveled. Thus, understanding the mechanisms of the relationship between the protein structure and composition will effectively manage the creation in vitro of a new tissue with native properties.

Different Conditions for the Modification of Polycaprolactone Films with L-Arginine.

Poly-ε-caprolactone (PCL) is a biodegradable polymer used in regenerative medicine. Mesenchymal stem cells (MSCs) play an important role in the regeneration of different tissues. The hydrophobicity and neutrality of a PCL surface reduce MSCs' adhesion and proliferation. In this study, PCL films were treated with arginine to improve surface hydrophilicity. The influences of arginine concentration, temperature, and solvent on PCL surface properties were investigated. PCL films treated with a solution of arginine in isopropyl alcohol were found to have the maximum number of amino groups. The greatest number of cells, 2 h after seeding, adhered to such films. It was shown that amino groups affect the interaction of cells with a modified surface and the hydrolysis reaction after treatment with isopropyl alcohol promotes the formation of adhesive focal contacts. Hence, our results illustrate that functional groups on the PCL surface after arginine solution treatment regulate MSC adhesion and focal contact formation.