Recent experimentation has been aimed at utilizing animal cells for human recovery from diseases, such as Parkinson's. Scientists hope to use cloned cells to replace improperly functioning cells in patients, thereby reducing tremors and other symptoms. Although the research is in its early stages, if it proves successful the medical world could be revolutionized. However, concerns such as the possibility of transmitting animal disease to humans through cell transplantation and the ethics of genetic cloning are problems that may hinder future developments.