Human body cells
Recent estimates put the number of cells in an average human body at 37.2 trillion. A cell has three parts: membrane, cytoplasm and nucleus. The nucleus is the control centre and contains the DNA, which stores genetic instructions to create an organism. The nucleus also holds RNA and proteins. RNA influences how genes are read, which determines individual characteristics. The nucleus also contains 23 pairs of chromosomes, which consist of a strand of DNA with hundreds or thousands of genes. A gene is a segment of DNA with information on heredity. The 20,000 or so genes in the genome also encode information for making proteins, which are the building blocks for making all body structures (skin, tissue, organs etc).
Genes and stem cells
Gene therapy began in the 1990s, when researchers discovered how to correct or influence how genes function. This knowledge was used in new treatments for blood disorders and degenerative muscle diseases. Gene therapy delivered a functional copy of a damaged or missing gene into affected cells, using a virus as courier. As technology has progressed, some newer approaches have moved away from the delivery of healthy genes and instead directly target an affected gene within the cell. In particular, the CRISPR method employs molecular tools that can modify or remove the affected gene. This method of gene editing was initially used in trials focused on specific conditions, such as sickle cell disease. Scientists are now investigating a range of treatments for cancers, neurological diseases and autoimmune disorders.
Stem cell research plays a key role in regenerative medicine, which involves replacing or renewing damaged or diseased cells, tissue or organs to restore their normal function. Stem cells enable us to develop from one cell into an adult human, to make new tissue, heal broken bones and replace injured skin. We have to make cells constantly to keep our bodies functioning and we rely on stem cells to replace specialised cells that are impaired or used up. Stem cells are defined by two key characteristics: the ability to continuously divide and produce exact copies (self-renewal); and the ability to change into a specialised type of cell (differentiation).
Stem cell therapies are currently used in certain surgical operations, such as bone marrow transplants and skin grafts. The development of a new treatment can take a long time, however, and some experts think it may be another 15-20 years before curative stem cell therapies become widely available. People who may eventually benefit from stem cell treatment include those with spinal cord injury, Parkinson’s disease, stroke, cancer, heart disease and osteoarthritis.
Organoids, transplants and the brain
Stem cells are used in the lab to grow organoids – tiny tissue cultures that can replicate much of the complexity of an organ, or convey aspects of it. Study of organoids can provide insights on human development and disease, as well as allowing scientists test new drugs. Novel technologies include: implanted 3D-printed scaffolds for bone and tissue regeneration; and retinal organoids grown from skin stem cells.
Scientists have also created mini-hearts and mini-brains that are starting to act like developing human hearts and brains. This could possibly lead to a form of consciousness, where lab-grown brain organoids become capable of thought and human-like emotions, as their size and lifespan increase. Their behaviour has already reached a point where they show signs of intelligence, and some experts are asking if they should be accorded legal status, such as the right not to be treated badly.
The first successful human organ transplant was performed in 1954, when a kidney was donated between identical twins. Use of drugs to combat rejection has allowed some types of transplant operations to become routinely effective, with successful womb transplants from living donors being a recent advance. The goal of using a patient’s own cells to grow stem cell-based internal organs for transplantation back into their body has not yet become reality
In the Lifespinners world of 2048, regenerative medicine has made enormous strides, our modern life-threatening diseases no longer trouble its privileged older residents and the focus is turning to high-tech methods of brain and mind enhancement. The dilemmas that this raises are highlighted by 80-year-old Isabel, the main character, who declares: ‘I don’t want to get into mind … control, exposing our most intimate thoughts and treating our inner space like it’s outer space, a frontier of discovery and something to battle over, mine for resources and colonise for human expansion.’
Artificial intelligence and robotics
Artificial intelligence techniques are capable of unveiling our brain processes and indicating how we can change and improve aspects of thinking, memory, creativity and emotions. In healthcare, AI is now seen as an invaluable aid in tasks such as assessing cancers, recognising anomalies on imaging tests and predicting level of risk in childbirth. AI can also help in the design of drugs and treatment approaches and the search for clues in curing serious diseases.
Mental health is another developing field for AI, with some experts envisaging digitally-driven personalised care that offers ready tools to manage challenging situations. Therapy chatbots are becoming more common in treatment and some draw on well-recognised methods such as Cognitive Behaviour Therapy, which has a specific structure and set exercises. This can reduce the risk that the chatbot acts unpredictably, although research is still needed on ways to ensure they are reliable and don’t cause harm. On the positive side, some patients may find that they can relate more easily with a bot than with humans.
Robots come in an increasing variety of shapes and sizes, ranging from the tiniest nanobot to walking humanoids and giant industrial machines. While traditional robots have rigid structures, soft robotics has introduced materials and features that include sensory skins and fabricated muscles. This has led to the development of flexible devices that give the robot a sense of touch and an awareness of the surrounding environment. The technology is expected to have applications in areas like the design of surgical tools and prosthetics. In other developments, mini magnetic robots and computer-designed organisms (xenobots) made from animal stem cells could have many practical uses, such as transporting drugs within the body or extracting foreign objects.
Robots have progressed from manufacturing and gaming environments into personal social contexts, such as care homes and schools. In these settings, they need to be relatable, trustworthy and in some cases persuasive. Studies have explored the Uncanny Valley theory, which suggests that humans become more uncomfortable as robots become more human-like. While there are both evolutionary and cognitive explanations for this response, it may be that it will gradually reduce with greater familiarity, along with more confidence that we humans remain in ultimate control.
Virtual reality (VR) is rapidly expanding in healthcare, where it has proved to be an effective pain relief tool. Being immersed in a calming virtual landscape can reduce pain during unpleasant medical procedures. Digital avatars have also been used to represent the voices heard by people with psychosis, while surgeons in different locations have performed surgery together and VR therapy is employed to support people with conditions and illnesses ranging from autism to visual impairment, cancer and mental ill-health. Patients are given tasks to carry out in virtual environments, facilitating a holistic approach that extends to individual lifestyle and other factors relevant to their condition.
Virtual representations of the real world – known as digital twins – are now common in industry. As examples, there are digital doubles of cities, ports and power stations. The idea has moved into biology, with predictions that humans may soon have a digital twin created at birth. In personalised medicine, the twin could be used to inform medical decisions on treatments and predictions of how a particular disease might develop. Many projects are at an early stage but they include research aimed at twinning or emulating the brain. As with growing brain organoids, digital brain twinning poses stark ethical questions: Who owns the twin? Does the twin have rights? Where does its data go after the person dies? And perhaps most intriguingly, what happens if someone wants to choose their super-fast digital brain in preference to their natural one?
Edited Autumn 2023