Compositions, e.g., gels, useful for tissue resection procedures, medical devices comprising the compositions, and related methods of preparing the compositions are discussed. The composition may comprise gellan gum, two or more salts, and water. In some aspects, the composition may be prepared by combining gellan gum and water to form a pre-mixture, heating the pre-mixture, adding two or more salts to the heated pre-mixture to form a mixture, introducing the mixture into a reservoir, and allowing the mixture to form a gel inside the reservoir. The gel may have a continuous, three-dimensional structure, and have desired gel strength and viscosity. The composition may be biocompatible and injectable from the reservoir through a needle to the target site of a patient.
