Regeneration always reminds me of the Doctor in Doctor Who. He (or she, in most recent episodes) has the ability to regenerate into a different person altogether. Unfortunately, the Doctor is an alien and a fictional character. So we are far from having this ability. However, regeneration can be in the form of regrowing limbs. Although that is less exciting, it is a phenomena seen in fish that could revolutionise regenerative medicine.
Particularly lungfish, salamanders and zebrafish.
These fish can regrow their tails and fins after losing them during a fight or a predator attack. Salamanders and zebrafish have this ability which is separate from humans, however, lungfish are related to humans on the evolutionary tree. Researchers took a phylogenetic approach by finding out our evolutionary relationship.
A lungfish receives these alien features from a vertebrate ancestor. Vertebrates have a spinal cord surrounded by cartilage or bone. Examples of vertebrates are birds, fish, amphibians and mammals. Therefore, we are vertebrates too. In fact, lungfish are our closest fishy relative. Lungfish have the same muscle, bone and nerve tissue found in our arms and legs, in their fins. The only difference is that lungfish can repair their spinal cord but human spinal cord injuries are permanent. Maybe one day doctors will be able to regrow our limbs if researchers find out how to apply the capabilities of lungfish to humans. Regeneration could take a completely different route to stem cell research making it more likely that we will find a treatment for spinal cord injuries.
When lungfish lose a tail or fin, everything lost must be replicated cell by cell, until the entire tail/fin has regrown in a few weeks. Macrophage cells rush to the site of the wound in an immune response. Macrophages are large white blood cells that are specialised in removing dying or dead cells. These cells are also found in us!! They devour pathogens and activate healing by signally anti-inflammatory parts of the brain. Thus, creating another link between humans and lungfish. Research has also found that the genes involved in regeneration are involved in embryonic development, which means it is responsible for growth and specialisation of cells.
The last questions researchers have to investigate is whether or not lungfish developed this trait after separating off from humans (in the evolutionary tree) or humans lost the trait. We also then need to figure out how to switch genes on in the human genome to make regeneration a possibility.
It seems like a distant dream to be able to regrow our limbs but biotechnology has come a long way in the last 10 years such as the invention of CRISPR technology in 2013. CRISPR uses bacterial systems to edit the genomes in humans to get rid of genetic mutations. Something like CRIPSR has become a recurring topic in the science community so why can’t regeneration?