One aspect of the present invention generally relates to methods of sealing a wound or tissue plane or filling a void splace. In a preferred embodiment, the wound is an ophthalmic, pleural or dural wound. In certain instances, the compositions used to seal the wound or tissue plane comprises a polyalkyleneimine. In a preferred embodiment, the polyalkyleneimine is polyethyleneimine. Treatment of the polyethyleneimine with a cross-linking reagent causes the polyethyleneimine polymers to polymerize forming a seal. In certain instances, the cross-linking reagent is a polyethylene glycol having reactive terminal groups. In certain instances, the reactive terminal groups are activated esters, such as N-hydroxy succinimide ester. In certain instances, the reactive terminal groups are isocyanates. In certain instances, the polyethyleneimine has a lysine, cysteine, isocysteine or other nucleophilic group attached to the periphery of the polymer. In certain instances, the polyethyleneimine is mixed with a second polymer, such as a polyethylene glycol containing nucleophilic groups. In certain instances, the compositions used to seal the wound or tissue plane are formed by reacting a polyalkyleneimine bearing electrophilic groups with a cross-linking reagent containing nucleophilic groups. In certain instances, the electrophilic groups on the polyalkyleneimine are activated esters, such as N-hydroxy succinimide ester. In certain instances, the compositions used to seal the wound or tissue plane are formed by reacting a polyalkyleneimine bearing photopolymerizable groups with ultraviolet or visible light. Compositions used to seal the wound which contain PEI or a derivative of PEI are found to adhere tightly to the tissue. Other aspects of the present invention relate to methods of filling a void of a patient or adhering tissue. In certain instances, the methods use a polyalkyleneimine. In a preferred embodiment, the polyalkyleneimine is polyethyleneimine. Another aspect of the present invention relates to a polymeric composition formed by exposing a polyalkyleneimine to an activated polyalkylene glycol. In certain instances, the composition is attached to mammalian tissue.