Figure 7.

Immunostaining was performed on tissues harvested from the AV loop chambers after two weeks in vivo. Sections were stained for desmin (green), B3T (red), and DNA (blue). Examples of angiogenesis are marked with dotted lines. Arrows point to neuronal outgrowth. Asterisks label GelMA. (A) After two weeks of implantation, sections from the GelMA-only controls demonstrated angiogenesis and neuronal sprouting without muscle formation. Blood vessels were identified as ringed desmin-positive structures due to the smooth muscle encircling the vascular wall. Neuronal outgrowth was observed as clusters of B3T-positive cells. H&E staining revealed the inert characteristics of GelMA, which after two weeks showed no muscular, neural, or vascular growth within the material. (B) In contrast, tissue from chambers that housed bioprinted grids demonstrated muscle regeneration and maturation. Axonal outgrowth and angiogenesis were present throughout the developing muscle fibers. (C) Confocal micrograph of a 2.38 mm bundle of mature skeletal muscle from one of the chambers that housed bioprinted muscle. Inset is the magnified image of neuronal growth within this muscle bundle.