Magnesium Modifies the Structural Features of Enzymatically Mineralized Collagen Gels Affecting the Retraction Capabilities of Human Dermal Fibroblasts Embedded within This 3D System

Abstract

Mineralized collagen gels have been developed as in vitro models to better understand the mechanisms regulating the calcification process and the behavior of a variety of cell types. The vast majority of data are related to stem cells and to osteoblast-like cells, whereas little information is available for dermal fibroblasts, although these cells have been associated with ectopic calcification and consequently to a number of pathological conditions. Therefore, we developed and characterized an enzymatically mineralized collagen gel in which fibroblasts were encapsulated within the 3D structure. MgCl2 was also added during gel polymerization, given its role as (i) modulator of ectopic calcification; (ii) component of biomaterials used for bone replacement; and (iii) constituent of pathological mineral deposits. Results demonstrate that, in a short time, an enzymatically mineralized collagen gel can be prepared in which mineral deposits and viable cells are homogeneously distributed. MgCl2 is present in mineral deposits and significantly affects collagen fibril assembly and organization. Consequently, cell shape and the ability of fibroblasts to retract collagen gels were modified. The development of three-dimensional (3D) mineralized collagen matrices with both different structural features and mineral composition together with the use of fibroblasts, as a prototype of soft connective tissue mesenchymal cells, may pave new ways for the study of ectopic calcification.

Asthma-derived fibroblast to myofibroblast transition is enhanced in comparison to fibroblasts derived from non-asthmatic patients in 3D in vitro culture due to Smad2/3 signalling

“…Very often it is related to concentration of the gel, or conditions during polymerization. The collagen concentration that we examined was partially based on the literature where it is ranging from approximately 0.5 to 5 mg/ml for fibroblastic cells (Adachi et al, 1998;Sawhney & Howard, 2002;Brown, 2013;Boraldi et al, 2016). It should be noted here that according to some research, the real collagen concentration in such setting can be non-homogenous and increases even by two-folds in proximity to the bottom because of the influence of gravity during the polymerization process (Brown et al, 2005).…”

Mineralization by mesenchymal stromal cells is variously modulated depending on commercial platelet lysate preparations

“…With regard to the cell-specific response to promineralization stimuli, dermal fibroblasts have been shown to osteogenically differentiate upon transfection of an osteogenic transcription factor [37] or when cultured in an appropriate mineralizing environment [38][39][40][41]; however, the degree of similarity between hMSCs and HDFs varies [42][43][44]. Of note, nHDFs and aHDFs did not mimic the prompt and dense nodular mineralization pattern of hBM-MSCs.…”