Parasite Eve by Hideaki Sena

When Dr. Nagashima loses his wife in a mysterious car crash, he is overwhelmed with grief, but also an eerie sense of purpose; he becomes obsessed with the idea that he must reincarnate his dead wife. Her donated kidney is transplanted into a young girl with a debilitating disorder, but the doctor also feels compelled to keep a smallĀ  sample of her liver in his laboratory. When these cells start mutating rapidly, a consciousness bent on determining its own fate awakes from an eonic sleep.