Today, we’re finishing our series on organ and tissue replacement through the revolution of bioengineering. Here, we’ll be looking specifically at fully-biological techniques. It’s all very well having pneumatic hearts and metal knees, but what’s likely to be the best approach for most patients is to do a “new for old” swap. Filling people up with engineering hardware is a distinct second-best.
You may be surprised what we can now regrow. To start with, we’ll continue our theme of bioengineering from yesterday. Then, we’ll finish up by looking at true organ regeneration – the “holy grail” treatment for organ failure.
Many important parts of the body are based on cartilage. It’s a resilient, rubbery tissue. Noses, ears and knees all rely on it to function. All of the above can be severely damaged in normal life, as can easily be seen by looking at cauliflower-eared rugby players. Fortunately, it’s now becoming possible to routinely regenerate complex cartilaginous structures using a collagen scaffold technique. One particularly important application is the re-creation of a damaged trachea (windpipe). This is considered a Level 2 organ, on a complexity scale of 1 to 4 – which basically means a pipe. The first tissue-engineered tracheas were implanted six years ago. Cartilage is rapidly looking like one of the big stories in bioengineering. It’s just a matter of waiting for it to move to the mainstream.
Researchers at Imperial College London are experimenting with “bio glass” – a material that’s previously been used to promote bone healing, in an application dating back to the Vietnam War. The advantage with this approach is that the material can now be made springy, as well as being 3D printable. That makes it ideal for making custom cartilage scaffolds, which will become living tissue in due course.
Firms to watch: CartiHeal.
Blood from stem cells
Blood is used very widely, for trauma victims, haemorrhage patients and in major surgery. Collecting it from donors requires a large and complex supply chain as blood has a short shelf life. Further, it incurs risk – and a range of very nasty diseases can be transmitted through transfusions. Being able to properly synthesise blood would be a huge boost, not least because blood from young donors has been shown to have rejuvenating effects. If we could make blood production routine and simple, it may become used far more widely than is presently the case; perhaps being used as a routine maintenance therapy, for the elderly.
An alternative strategy is to create blood substitutes. These can be used simply to “bulk up” the blood, providing additional liquid volume. A much more advanced approach than this bulking-up is to use synthetic chemicals, which are capable of carrying oxygen around the body – just like the real thing.
Firms to watch: NuVox Pharma, Tenax Therpeutics.
It’s perfectly normal for men to have a very high proportion of sperm that can’t swim. However, if this proportion gets too high, it can make conception impossible. One well-tested technique to treat this is the injection of sperm right into the egg, known as intra-cytoplasmic sperm injection (ICSI). However, an alternative technique has been demonstrated by German researchers. They’ve fitted miniature submarines to sperm, to help them swim. (ACS Nano Letters)
A more advanced approach is to trigger cells to produce gametes (sperm and eggs) outside the body. This will have a large range of potential uses. Those who were born without gonads, or who have lost them due to illness or injury, would then be able to produce biological children. But the technique also has great promise to help gay and lesbian people have full biological children with their partners. This technique already works to produce animal eggs. A well-placed industry source tells me his firm could do it today, in humans – if it weren’t for ethical and legal hurdles.
Artificially triggered organ growth
The Holy Grail of regenerative medicine is to get the body to grow new parts, all by itself. You grew all the bits of your body in the womb – so with the right kind of fiddling, it should be possible to grow them again. You may be familiar with lizards that can shed and regrow their tails. That’s an example of a process called autotomy: where body parts are discarded. Florida stone crabs can regrow their claws, which are harvested by fishermen. In humans, we’re far off this – but nevertheless, there has been significant progress. Spinal cord repair is now becoming possible, with some patients having movement and sexual function restored. Regrowing extremities is an obvious target to aim for; digits and limbs are often lost in accidents, and other injuries.
An alternative implementation of this kind of approach is to enable a kind of xenotransplant. These are transplants where the organ is grown in a different kind of animal. For example, it’s possible we could live with a pig heart in us. However, an improvement to this potential technique has already been demonstrated. This involves manipulating an embryo, to prevent normal organ development. Then, the developing animal is implanted with tissue from another species. In a recent Nature paper, a mouse pancreas grew in a rat. This worked, when transplanted into a mouse.
This research is some way off clinical application to humans, but it shows real promise for the future. An endless supply of pig-grown replacement organs would potentially keep us in fine fettle, even if we lived incautiously. The ability to use biologically-human organs should get around problems with rejection, and also address issues arising from the more rapid ageing of donor animals.
It’s plain to see that this field of medicine is striding ahead. In time, we can expect greatly increased use of replacement organs and tissues, with bioengineering likely to become commonplace. Cybernetics will continue to play a part – but for the majority of patients, a living-tissue replacement will be preferable to an implanted electronic device. Sadly, we’ll have to wait a while for our own personal pig, equipped with human organs. But if and when this comes, we’ll be able to get an endless supply of replacement organs – and plenty of bacon and scratchings, to fur up our new arteries.
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Category: Genetics and Biotechnology