These technologies are already being used to treat some human diseases. In 2025, Baby KJ received a personalised base-editing therapy, with encouraging clinical improvement and ongoing follow-up. Similar tools are being developed for a host of other genetic disorders, for infectious diseases, and even for heart disease and severe epilepsy.
Similar techniques are being developed for non-human cells such as bacteria, fungi and plants. These tools should enable the development of suites of microbes that can restore polluted soils and waterways; the creation of new crop varieties that are resilient to climate stressors such as drought; and the synthesis of essential vaccines and materials by engineered biofactories.
Two barriers must be overcome if these biotechnologies are to come to fruition. The first is procedural: reliably delivering the tools to the specific cells in which we wish to intervene. While this is now readily achievable with single-celled organisms, it remains challenging for most of the organs of the human body, for many crop plants, and for fungi. Reliable and efficient delivery systems are essential for these medical treatments and technologies to be cost-effective.
Finally, all these technologies are utterly dependent on progress in fundamental biology. In particular, the complex interactions between different parts of the genome and the epigenetic markers controlling the expression of genes must be unravelled. It is also necessary to understand how these processes vary in different cell types, organs and organisms. Without this understanding, our interventions are likely to fail, or to create too many undesirable off-target effects. Only with a rich understanding of how different cells work will it be possible to create cell and gene engineering methods that are widely applicable.
Key takeaways
Biologists are increasingly able to engineer genes, entire genomes, and living cells. These methods will help us understand fundamental biological principles, such as how cells function and how organisms develop. They also have great potential to advance human welfare, for example through new medical treatments and by creating climate-resilient crops. Human cell engineering is often performed using DNA-based methods but also encompasses an array of other techniques. By tinkering with the internal mechanisms of cells, researchers hope to learn more of the underlying principles of human biology. They also hope to develop novel treatments for serious health conditions that are currently unmedicated, and to improve the success rates of existing procedures such as organ transplants. Meanwhile, non-human cell engineering has the potential to help solve major global problems such as food insecurity: crops can be modified using multiple techniques to become more nutritious or resilient. Microorganisms like fungi and bacteria can become factories producing useful chemicals and materials. At the heart of many of these efforts are technologies for editing the genome. Tools like CRISPR-Cas9 and base editing allow geneticists to rewrite organism’s DNA with unprecedented precision, and at growing scale. Already, these tools have been used to cure rare genetic diseases, saving lives. An alternative to directly altering the genome is controlling the epigenome, the array of chemical markers that influence which genes are expressed when. Epigenetic markers can now be mapped in detail, and new tools can either modify them or, if necessary, circumvent them altogether by inserting long stretches of unmarked DNA. The goal here is epigenetic therapies for severe conditions such as chronic hepatitis B infection.
Such interventions help researchers to better understand how a cell functions. Human cell engineering will therefore help us understand fundamental human biology. This includes deciphering the functions of genes and proteins, understanding how cells transform from one type to another, and tracing development from conception to adulthood. It also promises to shed light on the causes of disease and how diseases affect bodily systems.
Human cell engineering has enormous medical potential. Harmful genetic mutations can be corrected using editing tools like CRISPR-Cas. Damaged cells may be replaced with healthy ones produced from stem cells,3 helping to heal wounds and injuries.4 Cells can also be engineered to have therapeutic functions. One prominent example is chimeric antigen receptor T cells (CAR T-cells), which are immune cells engineered to target a specific protein and which are in this way being used to destroy cancer cells.5
One significant opportunity is to improve the success rate of organ transplants. Currently, to prevent transplanted organs being rejected by the immune system, patients must take immunosuppressant drugs, leaving them at greater risk of infection. However, studies suggest it is possible to prevent immune rejection by bioengineering. Targeted disruption of genes involved in immune recognition has shown promising results in the lab and could reduce or even eliminate the use of immunosuppressants.6 The same approach could be used in cell therapy, enabling cells produced from another person’s stem cells to be safely injected.7
These cell and gene therapies face a number of challenges. One core problem is delivering the therapy to the specific cells at the root of the disorder. Researchers have developed an array of delivery methods: these include lipofection, electroporation, viral vectors, extracellular nanovesicles8 and lipid nanoparticles9 that can carry CRISPR systems, mechanisms for transferring macromolecules via cell-to-cell contact,10 and miniaturised enzymes that can more easily enter human cells.11 Nevertheless, confirming that the therapies have had the desired effects within cells remains difficult,12 as does tracking unintended and off-target effects.13
This is exemplified by the ongoing efforts to treat muscular dystrophy by correcting the root mutation in the dystrophin gene.14 While there is evidence that the damaged gene was successfully replaced,15 this has nonetheless not yet translated into improvements in patient outcomes. Likewise, the cardiovascular drug pelacarsen proved able to lower levels of lipoprotein A, but did not improve patient outcomes.16
There have been success stories, however. Gene therapies for people with sickle cell disease are highly effective,17 and have been approved in multiple countries including the US and UK.18,19 Likewise, 2025 saw the dramatic case of Baby KJ, who received an individualised gene-editing therapy to resolve a rare genetic disease,20 severe carbamoyl-phosphate synthetase 1 deficiency.21 The challenge is to make such therapies available for all genetic disorders.
