Another Step Towards Early Artificial Cells
It is worth keeping an eye on progress towards the creation of artificial cells and cell-like structures, as they are potentially useful in a very broad range of biotechnologies relevant to longevity science, regenerative medicine, and so forth. The first swarms of medical microrobots will quite likely be modified cells or artificial cells, packed with specific forms of molecular machinery to achieve some sort of effect in the body - such as manufacturing signaling compounds in response to local conditions, so as to steer the activities of surrounding cells.
A custom-built programmable 3D printer can create materials with several of the properties of living tissues. The new type of material consists of thousands of connected water droplets, encapsulated within lipid films. Because droplet networks are entirely synthetic, have no genome and do not replicate, they avoid some of the problems associated with other approaches to creating artificial tissues - such as those that use stem cells. Each droplet is an aqueous compartment about 50 microns in diameter. Although this is around five times larger than living cells the researchers believe there is no reason why they could not be made smaller. The networks remain stable for weeks."We aren't trying to make materials that faithfully resemble tissues but rather structures that can carry out the functions of tissues. We've shown that it is possible to create networks of tens of thousands of connected droplets. The droplets can be printed with protein pores to form pathways through the network that mimic nerves and are able to transmit electrical signals from one side of a network to the other."
Link: http://www.sciencedaily.com/releases/2013/04/130404142457.htm
This is a small step in a long process to develop regeneration based purely on synthetic biology.
I have never heard the idea of creating synthetic, enhanced mitochondria put forward, but it seems like one of the more promising and relatively near term medical uses of synthetic biology. Mitochondria are known to possess a role in cell cycle signalling and the induction of apoptosis. This means that engineered mitochondria would have a pathway through which they could arrest the development of cancer (which is much easier to detect from the cytoplasm than from the cell surface). Synthetic mitochondria could replace senescent ones and provide more comprehensive anti-cancer functions, with genomes in the size regime of those that have already been synthesized.
More speculatively, they could also provide the ability to derive energy from new kinds of metabolic substrates. Burning sugar has worked for Animalia to this point, but maybe other possibilities could have their own advantages (like higher energy density, better potential for storage than volatile gasses like O2, fewer harmful by-products, etc.)