Muscle tissue engineering has also garnered attention over the years (Figure ). Gelatin methacryloyl (GelMA) is a bioink that can mimic the native skeletal muscle tissue environment. This hydrogel has promising potential as it is mixed with alginate for desired bioprinting viscosity. Cell-laden GelMA microfibers are bundled. By working on the swelling properties and folding abilities, the cell-laden GelMA microfibers can be used to mimic the structure of different skeletal muscle tissues. For smooth muscle tissue fabrication, collagen laden with smooth muscle cells form line patterns with layer-by-layer deposition and demonstrate uniform cell seeding with controlled resolution. Cardiac muscle tissue or heart organ applications commonly use hydrogel bioinks. Rather than creating an entire organ, cardiac patches can be created from the patient's fatty tissue. The cells from the patient are reprogrammed to pluripotent stem cells, and the collected extracellular matrix is processed into a hydrogel. This eliminates the risk of implant rejection because the printed scaffold is biocompatible. The result is a bioprinted thick, vascularized, and perfusable cardiac patch that will match the immunological, biochemical, and anatomical properties of the patient. The patch allows stem cell adhesion, differentiation, and proliferation to a damaged heart, improving wound healing and functional preservation.