1 John 3:16 (KJV) Hereby perceive we the love of God, because he laid down his life for us: and we ought to lay down our lives for the brethren.
It is not a bad thing if we donate a part of our lives or our body to save life. The Bible teaches us to lay down our lives for others. That just as Jesus Christ gave His life for us, we are admonished in the Bible to lay down our own lives for others.
The Christian life is that of love. We should love to the extent of laying down our own lives for the brethren. We should sacrifice whatever we can to save the lives of our brethren. We should be much concerned with the happiness and wellbeing of our brethren. It is not a bad thing if we can offer our own organs or blood to save the lives of others.
Love will always give. God taught us love so that we might love the brethren. True love will go all the way to save the lives of the brethren. So, whatever we can do in service or kind for the happiness and safety of the brethren, let us do it.