Use of Foetal Tissue Grafts in Treatment of Parkinson's

Research into Embryonic Stem cells has gone so far that foetal tissue has actually been implanted into Parkinson's patients' brains, the results however, have not been conclusive. The first studies that were conducted transplanting human foetal tissue were started in 1987 (1) and have been continued to this day. The type of implanted tissue has been varied to find the type of foetal tissue that would most efficiently survive in an adult brain as a Dopamine-secreting neuron. The foetal tissue is most often obtained through elective abortions, where mothers who want to have an abortion consent to the foetus being used in the study after abortion has taken place (2,3). I have not found a study that used surplus IVF embryos as tissue graft source.

When I heard of this the first time, I felt like something turned around inside me. I know the principle is similar to organ donation after a person has died. But an embryo cannot "consent" to its tissues being used for research or the treatment of another person's illness. The question that is even more important though is "Where does Human Life begin?" Does it begin at conception, which would be the most logical answer, or at somepoint later on? Maybe once a human form has begun to be visible? The potential to form each one of us was stored up in that single fertilized egg. I don't want to judge the women who have had abortions, no doubt their position is a very difficult one and I only hope to imagine some of the pressures that must be faced by them. I just want to remind us all of the immense value of a human life, be it contained in a fully developed human like you and me, or in an undeveloped human seen in a fertilized egg. 

Please feel free to comment - I would very much like to see your point of view!

References:

(1) Lindval O, Björklund A (2004): "Cell Therapy in Parkinson's Disease" in The American Society for Experimental NeuroTherapeutics 1(4): 382-393 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC534947/

(2) Kordower J H, Freeman T B, Snow B J, Vingerhoets F J G, Mufson E J, Sanberg P R, Hauser R A, Smith D A, Nauert G M, Perl D P, Olanow C W (1995): "Neuropathological Evidence of Graft Survival and Striatal Reinnervation after the Transplantation of Fetal Mesencephalic Tissue in a Patient with Parkinson's Disease" in The New England Journal of Medicine 332: 1118-1124 
http://www.nejm.org/doi/full/10.1056/NEJM199504273321702#ref16=&t=articleMethods

(3) Strömberg I, Almqvist P, Bygdeman M, Finger TE, Gerhardt G, Granholm A, Mahalik TJ, Seiger A, Olson L, Hoffer B (1989): "Human Fetal  Mesencephalic Tissue Grafted to Dopamine-Denervated Striatum of Athymic Rats: Light- and Electron-Microscopical Histochemistry and in viva Chronoamperometric Studies" in The Journal of Neuroscience 9(2): 614-624 

http://www.jneurosci.org/content/9/2/614.full.pdf