The invention relates to implantable collagen devices made by seeding at least one elongate collagen construct, e.g., comprising at least one elongate synthetic collagen fiber with a plurality of cells and applying a strain and/or stress to the at least one elongate collagen fiber to induce the cells to differentiate into target phenotypes, e.g., tendon or ligament phenotype cells (and/or fibroblasts), typically with an extracellular matrix of collagen to organize into a tissue on the at least one collagen fiber.
