"...Use of a non-living component. Using the limb of those animals permissible to eat and slaughtered according to the Islamic rites of slaughter. There is almost certain fear of loss of life or danger of losing the limb/organ and the replacement is only found in haram animals or in permissible animals (which can be eaten) but not slaughtered according to Islamic rites, then use of such a component will be permissible. However, if there is no imminent danger of loss of life then it will not be permissible to use anything from the pig."

http://www.albalagh.net/qa/blood_transfusion_transplant.shtml