Provided is a medical device formed entirely from or formed partially from a polymer, e.g., a polysaccharide such as chitosan. In some embodiments, the medical device may be formed as a sheet of a chitosan material. This chitosan sheet may be used to wrap around tissue, such as a nerve or tendon to help with the regeneration or healing process of the nerve or tendon, as applicable. In addition or in the alternative, the sheet may be wrapped to form a tube or other shape that can wrap around the nerve.