Study of the feasibility of a soft gelatin methacryloyl-based template to develop cell-derived matrices for screening patients with congenital muscular dystrophies

Collagen VI-related muscular dystrophies (COL6-RD) are a family of rare diseases associated with collagen VI deficiency, such as the severe Ullrich Congenital Muscular Dystrophy or the intermediate forms of Bethlem Myopathy. The life quality of patients with COL6-RD is highly reduced, due to disabling symptoms, such as respiratory insufficiency, weakness, loss of independent mobility, and joint contracture. Overall, life expectancy is highly decreased, but, to date, there is no effective therapy. Dominant or recessive mutations in one of the three collagen VI genes are considered to be the onset of these diseases. The integrity of the fibrillar network of the collagen VI is lost, altering the incorporation in the extracellular matrix (ECM) and disrupting tissues homeostasis. Recent studies have revealed that patients' fibroblasts can be employed to explore the pathological characteristics of ECM related to COL6-RD, but further analyses are required to understand the mechanisms that regulate COL6-RD and ECM alterations at the molecular level. Hence, in vitro studies of the pathological ECM are required to investigate new screening methods and new therapeutic strategies. In this work, three different substrates for cell-derived matrices (CDMs) production were compared. In particular, a gelatin coating, previously employed in studying ECM fibrillar properties of healthy donors and patients, was juxtaposed to a novel gelatin methacryloyl (GelMA) and alginate methacrylate (AlgMA) interpenetrating polymer network (IPN) in form of a hydrogel. Indeed, the flat 2D microenvironment sensed by cells in the gelatin coating may limit the study of cells' morphology, migration, and interaction with the produced ECM. Therefore, two configurations were investigated: a hydrogel with a monolayer of mouse fibroblasts seeded on the top and a three-dimensional cell-laden hydrogel with a specific thickness. Indeed, developing a 3D CDM construct using patients' fibroblasts should further replicate the complex structure of tissues, allowing a more accurate analysis in a biomimetic environment. However, when cells were surrounded by the gel, viability was high, but fibronectin and collagen production diminished, suggesting cell suffering. In conclusion, in this previous study of CDMs, the 2D configuration resulted in being the better option for screening patients. Still, more investigations have to be carried out to obtain a 3D construct to help understand the mechanism of these rare diseases and develop new treatments.