passages.id: split_4_validation_1317_passage
passages.type: progene_text
passages.text: However , when administered to experimental models of fibrosis , H2 relaxin can only be applied over short - term ( 2 - 4 week ) periods , due to rodents mounting an antibody response to the exogenous human relaxin , resulting in delayed clearance and , hence , increased and variable circulating levels .