Skeletal Muscle Tissue Engineering: Methods and Analysis for the Bio-Fabrication and Validation of a 3D Scaffold-Free Muscle Construct.

The development of three-dimensional (3D) tissue constructs that accurately replicate the morphology and function of native tissues is critical for advancing tissue engineering and regenerative medicine. Two primary strategies are currently employed: scaffold-based and scaffold-free approaches. Both aim to reproduce a biomimetic microenvironment that supports cell-cell and cell-matrix interactions, enabling the formation of functional tissues. To circumvent the immunological and toxicological limitations related to the use of exogenous scaffold materials, scaffold-free tissue engineering has emerged as a promising alternative. This method utilizes multicellular aggregates that fuse into cohesive structures while naturally producing extracellular matrix (ECM). Harnessing the intrinsic capacity of cells to self-organize and assemble into sheets enhances cell-cell connectivity and promotes spontaneous ECM remodeling, facilitating the formation of scaffold-free tissues. This study outlines the methodology for generating a 3D skeletal muscle tissue in vitro without the use of scaffolds. Here, we describe key analytical techniques, including flow cytometry, immunofluorescence, and histological staining, used to evaluate tissue functionality in physiological and pathological contexts. The proposed protocols enable the creation of a mouse skeletal muscle model suitable for drug screening and testing, considering its advantages and limitations. Furthermore, the integration of patient-derived biopsies or induced pluripotent stem cells (iPSCs) establishes a basis for personalized therapeutic applications in clinical settings.