A tissue adhesives and sealant formed by reacting a polyglycerol aldehyde with a water-dispersible, multi-arm amine is described. The tissue adhesive and sealant may be useful for medical and veterinary applications, including, but not limited to, wound closure, supplementing or replacing sutures or staples in internal surgical procedures such as intestinal anastomosis and vascular anastomosis, tissue repair, preventing leakage of fluids such as blood, bile, gastrointestinal fluid and cerebrospinal fluid, ophthalmic procedures, drug delivery, and to prevent post-surgical adhesions.