CRISPR, Space, and Stem Cells: How 2024 is Shaping the Future of Regenerative Medicine
I was recently reading a study by Ghani and Zubair, published at the end of last month in npj Microgravity, about an experiment in space where scientists were growing stem cells aboard the International Space Station. It highlights how cultivating stem cells in space enhances their growth and regenerative potential. The microgravity environment aboard the International Space Station allows stem cells to expand in three dimensions without the influence of Earth's gravity, leading to higher-quality cells with improved therapeutic capabilities.
I’m pretty happy with my Tempur-Pedic pillow, but the idea of needing to grow stem cells in space sounded excessive. NASA has a long history of delivering unexpected innovations. Besides pillows, we now have scratch-resistant lenses from coatings made initially to protect astronaut helmets, and research on algae for astronaut nutrition led to the discovery of sustainable DHA and ARA, which are now common in baby formula because of their role in brain and eye development. The sustainability aspect means that algae can be grown and harvested in large quantities without the environmental impact or limitations that come with sourcing DHA from fish or ARA from meat. As for stem cells, space research actually provides conditions we can’t fully replicate on Earth. Microgravity helps improve the quality of stem cells in ways that advance medical science.
While we can use devices like clinostats on Earth to mimic some aspects of microgravity by continuously rotating samples to reduce the effects of gravity, these methods can’t fully replicate the continuous, sustained microgravity conditions found in space. True microgravity affects cell behavior, gene expression, and cellular interactions in unique ways we haven’t yet replicated on earth. Space-grown stem cells have shown enhanced proliferation and maintained their stemness (a stem cell's ability to self-renew and differentiate into various specialized cell types) better than those grown here on Earth.
I wanted to get a sense of where stem cell research stands in 2024, especially compared to the early days when therapies involved injecting large numbers of stem cells and hoping they’d work without causing harmful side effects. Thanks to advancements like CRISPR gene editing, we've moved beyond that 'inject and pray' phase, and stem cell treatments are now far more targeted and precise.
Stem cells have an ability to transform into different types of cells. However, not all stem cells are the same. Pluripotent stem cells, like induced pluripotent stem cells (iPSCs), can become any cell type in the body. iPSCs are reprogrammed from regular cells (like skin or dental pulp cells) into a pluripotent state, allowing them to turn into any cell, such as liver, heart, neurons, etc. Naturally occurring pluripotent cells are embryonic stem cells (ESCs), which can also become any cell type but are derived from early-stage embryos, making them ethically complex to source. As a result, most pluripotent cells used in research today are iPSCs, which are created by reprogramming adult cells, rather than directly deriving ESCs.
In the early days of stem cell therapy, Mesenchymal stem cells (MSCs), a type of multipotent stem cell, meaning they can differentiate into a limited range of cell types, primarily give rise to bone, cartilage, muscle, and fat cells, were harvested from bone marrow, which was an invasive procedure. Physicians would drill into your bones, usually the hip bone (iliac crest), to extract the marrow. This procedure required anesthesia, was painful, and carried risks of infection. Once the bone marrow was harvested, it would then be processed to isolate the MSCs, which could be cultured.
This process, while amazing that we could do it, was not too ideal. Harvesting enough MSCs for therapy was difficult and labor-intensive, and it wasn’t always possible to get enough cells. MSCs from bone marrow tend to decline in quality with age, meaning that older patients have less viable cells for treatment.
Thankfully, we no longer need to drill into bone to extract stem cells. We can still use bone marrow but MSCs can be obtained from adipose tissue (fat) through liposuction. Fat tissue contains a rich source of MSCs, and the process is much simpler, while allowing you to get a tummy tuck at the same time. Mesenchymal stem cells can be found in dental pulp, which can be extracted from your teeth, offering another non-invasive source. Because, you know, the dentist isn’t already expensive and feared enough. After just having a root canal, I’m still a little sensitive on the subject. Here's to regrowing that tooth someday. While I didn’t think of it at the time, if you ever go through the same thing and your pulp is viable, it could be sent to a lab for stem cell extraction. Those stem cells can then be stored in a stem cell bank for future use. Now that’s something to look forward to for the next visit!
In some cases, instead of needing to collect fresh MSCs, scientists can take somatic cells (like skin cells) and reprogram them into pluripotent stem cells (iPSCs). This means that, rather than drilling or extracting fat, we can use cells that are easier to access and then reprogram them for therapeutic use.? This is what I like, options.
You’ve likely heard of CRISPR but combining it with stem cells is what is pushing these major advances. CRISPR-Cas9, often described as molecular scissors, cuts specific DNA sequences to modify or delete genes, guiding stem cell differentiation and correcting genetic defects. Stem cell differentiation is the process where a stem cell transforms into a specific type of cell, such as muscle, nerve, or a liver cell. Using CRISPR, scientists can guide stem cells into the desired cell type by editing specific genes. In the case of genetic defects, CRISPR can be used to cut out the defective gene and replace it with a healthy one in the stem cells.
Once the stem cells are corrected, they can be reintroduced into the body, where they can multiply and (hopefully) produce healthy, functional cells. Now that the edited cells are genetically corrected, they will continue to divide and create healthy cells, effectively erasing the defect. This means that once the gene has been corrected in the initial stem cells, the fix is permanent, and the patient does not need repeated treatments to address the same defect.
I don't want to stray too far from the main discussion on stem cells, but it’s important to point out how CRISPR itself is making a lot of these stem cell advances a reality. While CRISPR can be used without stem cells to directly edit existing genes in a patient’s cells, the advantage of combining CRISPR with stem cells is the ability to create a renewable source of genetically corrected cells that can multiply and replace damaged tissue long-term. Most CRISPR work focuses on somatic cells (non-reproductive cells), meaning the genetic changes aren’t passed to future generations. However, in some cases, CRISPR could be used to edit germline cells, such as sperm, eggs, or embryos, to prevent inherited diseases like cystic fibrosis or Huntington’s. Though germline editing ensures these disorders aren’t passed down, it raises serious ethical concerns because it permanently alters the DNA of all descendants. For now, most CRISPR uses remain focused on somatic cells to avoid these risks.
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In the past, pluripotent cells (the kinds that can differentiate into any cell type in the body) were necessary because of their flexibility, but they came with risks such as uncontrolled differentiation or even tumor formation. Now, with CRISPR, scientists can precisely edit genes within multipotent cells like MSCs, directing them to become the exact type of cells needed for a specific therapy. This has eliminated the need for pluripotent cells in many treatments, reducing the risks associated with uncontrolled cell growth.
For example, in therapies like cartilage repair for hip labral tears (these are difficult to resolve due to poor blood supply, and surgery often leads to hip replacements later - they are increasingly common, especially in athletes), CRISPR can program MSCs to specifically become chondrocytes (cartilage cells), specifically targeting the damaged area and regenerating the tissue. This precision wasn’t possible in the past, and treatments relied on “hoping” (never a good strategy) that injected stem cells would migrate to the injury site and differentiate correctly.
A major advancement in stem cell and gene editing research has been the treatment of sickle cell anemia using CRISPR. In 2019, Victoria Gray became the first patient to receive CRISPR-edited hematopoietic stem cells (HSCs) to correct the genetic mutation causing sickle cell disease. The edited stem cells were reintroduced into her body, allowing her to produce healthy red blood cells and effectively eliminating the symptoms of the disease. This marked the beginning of clinical trials that have since shown promising results in other patients.
From what I’ve been able to find, Victoria is still doing well, and her therapy, known as Casgevy, was officially approved by the FDA in December 2023, marking a significant step for CRISPR-based treatments. While long-term monitoring of her condition will continue for 15 years, the results so far have been amazing and dozens of other sickle cell patients have benefited from the treatment.
This therapy was not possible just a few years ago, but CRISPR has allowed scientists to treat the genetic cause of the disease at its source. This development is a major milestone in using stem cells and gene editing to cure genetic diseases.
Globally, about 300,000 babies are born each year with sickle cell disease (SCD). It is also one of the most common hereditary blood disorders. Currently, around 100,000 people in the U.S. are living with sickle cell anemia, with the disease predominantly affecting African Americans. Worldwide millions are impacted by various forms of sickle cell disease. People with sickle cell anemia tend to live shorter lives, with life expectancy typically reduced by 25 years. Many individuals with sickle cell anemia face significant complications, including organ damage, infections, and painful crises throughout their lives.
Stem cell therapies hold promise for many common diseases that affect millions globally. Diabetes affects 537 million adults worldwide, and stem cell research is exploring ways to restore insulin production in Type 1 and potentially Type 2 diabetes. Cardiovascular disease, which leads to about 17.9 million deaths annually, is being targeted with therapies aimed at regenerating damaged heart tissue. For neurodegenerative diseases like Alzheimer's and Parkinson's, which impact around 55 million and 10 million people respectively, stem cells could replace damaged neurons and slow disease progression. Blood cancers such as leukemia affect hundreds of thousands worldwide, and advancements in stem cell transplants combined with CRISPR offer life-saving potential. COPD, affecting 65 million people globally, is another area where stem cell research is looking to regenerate damaged lung tissue. Finally, multiple sclerosis (MS), which impacts 2.8 million people, may benefit from therapies aimed at resetting the immune system and repairing nerve damage.
These therapies have evolved significantly from the early days of painful, invasive procedures. Today, we can reprogram ordinary cells into pluripotent stem cells, and CRISPR technology has opened the door to more precise, safer treatments using multipotent cells like MSCs, reducing the risks associated with pluripotent stem cells.
While space-based research is enhancing our understanding of how to grow better stem cells, the real advancements are happening here on Earth. The next challenge is scaling production to make stem cells widely accessible. Soon, high-quality stem cells will be mass-produced in Earth-based bioreactors, optimized to replicate the benefits seen in space-grown cells. Though we're still a ways from growing fully functional organs like livers or hearts, breakthroughs in gene editing, cell harvesting, and stem cell production are steadily pushing us toward transformative regenerative therapies.
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