Therapeutic symbiosis

People talk about using stem cells, nanobots, or viruses and other genetic therapies to fix storage diseases, or compensate for organ failure. However there is a possibly easier solution, using parasites and synthetic biology to engineer novel organisms. Malaria, TB, and a host of various protozoa’s (Trypanosomes) and worms have spent eons finding ways to live inside people by minimizing their signature on the immune systems “radar”. If we could engineer out the bad characteristics of these organisms like killing people, and say put in gene networks that would allow a malaria organism that was limited to the sporozoite stage and unable to replicate in humans to sense blood sugar levels and produce the required hormones we could use a tiny faction of the liver to replace the exocrine functions of the pancreas. The malaria organism would in effect become an endosymbiote, living in a host serving a function in exchange for room and board. We could replace the thyroid and parathyroid the same way.

The list of therapeutic symbiosis opportunities is endless:
-The Chagas organism (T. cruzi) could be used to stimulate the repair of damaged heart muscle.
-Mycoplasmas could be used to make semi-engineered mitochondria or other organelles that could be used to fix gene defects or to add novel functions like the ability to metabolize xenobiotics (from transfat to dioxins), make all the required amino acids and vitamins or even convert sunlight to energy using artificial chloroplasts.
-Engineered amebas could repair severed or demyelinated nerves.
-Engineered euglena could be used to reduce viral loads or clear the blood of bacteria in severe cases of sepsis.
-Worms could be designed to seek out tumors and form cysts in the capillaries, blocking the flow of blood and reducing the risk of metastasis.

The list goes on and on…

What I am suggesting is very dangerous since engineering organisms to replicate human metabolic functions even with “fool proof” safeguards is extremely risky. However, so is suppressing the immune system with drugs so people can live with transplanted organs.
Genetic therapies can cause cancer, so can stem cell therapies, and lord knows what tiny robots designed to repair cells could do if they break. No type of molecular medicine is without risk. I am not saying that we should engineer worms to replace our brains, but a worm that would eat arterial plaque might not as bad an idea as it sounds at first.

For anyone who thinks sharing your body with another organism is objectionable keep in mind there are more cells in you that aren’t you than there is of you. (Simplified. the bacterial cells in your gut alone significantly out number the cells in your body.) You play host to a variety of organisms from gut bacteria that actually feed you, to eyelash mites that feed vampirically on your skin cells, to a wide variety of intra-dermal fungi. Without this menagerie of organisms you would not thrive, so what are one or two more critters if they can save your life?