Abstract: One aspect of the invention relates to use of a composition comprising a purified inverse thermosensitive polymer in an endoscopic procedure for gastrointestinal mucosal resectioning in a mammal. Another aspect of the invention relates to a method of gastrointestinal mucosal resectioning, comprising administering submucosally to a region of a gastrointestinal mucosa in a mammal an effective amount of a composition comprising a purified inverse thermosensitive polymer; and surgically resecting said region of gastrointestinal mucosa. Yet another aspect of the invention relates to a kit for use in gastrointestinal endoscopic mucosal resectioning in a mammal, comprising a composition comprising a purified inverse thermosensitive polymer; a syringe; and instructions for use thereof.