#ScienceSaturday posts share exciting scientific developments and educational resources with the KAND community. Each week, Dr. Dominique Lessard and Dr. Dylan Verden of KIF1A.ORG summarize newly published KIF1A-related research and highlight progress in rare disease research and therapeutic development.
Therapeutic in vivo delivery of gene editing agents
This week we’re taking a step back from direct KIF1A research to discuss something very relevant to the KAND community: gene editing technology. Gene therapies are the holy grail of treating KAND and other monogenic disorders for good reason: changing mutated KIF1A back into its healthy form is the most direct type of treatment we could hope for. Gene editing technologies have made huge advances over the last decade, with the ability to insert, delete, or precisely modify the genetic code.
However, just like a slow release allergy pill isn’t only comprised of its active ingredient, effective gene therapies require more than just cellular gene-editing machinery. These treatments need to activate in the right cells at the right time to work as designed. In today’s #ScienceSaturday, we’re sharing a newly published review paper on how the way we package gene editing therapies can set them up for success and challenges that still need to be addressed.
Once they enter the body, gene editing agents need to go through several steps to work properly, most notably:
- Travel through the body without being degraded, and get to the right part of the body.
- Bind to the the surface of the right cells.
- Enter cells by crossing their membranes.
- Move between cellular compartments to their target.
- Precisely modify the target gene.
Each of these steps require different considerations depending on the cellular targets. So what solutions are being explored? The authors describe three different gene therapy delivery methods.
Lipid Nanoparticle Delivery:
Lipid nanoparticles are small spherical structures that are readily taken up by cells, then deliver mRNA into the cytoplasm. This results in short-term expression of the gene editing agent.
- Synthetic and less likely to cause immune response.
- Temporary expression of gene editing machinery reduces chance of off-target gene editing.
- Biodegradable with good safety profile.
- Can be manufactured at scale.
Challenges Being Addressed:
- Lipid particles are biased toward liver targeting when applied intravenously—customization for other organs is still being investigated.
Viruses thrive by transmitting between organisms, entering cells, and delivering DNA to the nucleus. By replacing viral DNA with the genes that encode gene editing agents, we can use the rest of the virus’ structure as a vehicle that transports gene therapies to their cellular target. The DNA cargo is integrated into the cells’ genome, leading to continuous expression of the gene editing machinery.
- Enters many different cell types effectively
- Well-characterized in model systems
Challenges Being Addressed:
- May activate immune system.
- Can only fit limited amounts of genetic material (this is a particular challenge for KIF1A, which is considered a large gene).
- Gene editing machinery may be continually produced after initial edits, increasing the chance for off-target effects over time.
Virus-Like Particle Delivery:
Rather than using viruses, researchers can also piece together different proteins from viral scaffolds. These viral-like particles can target and enter cells like viruses, but deliver mRNA or protein cargo instead of DNA. Because the gene-editing machinery isn’t integrated into the cell’s genome, it isn’t continuously expressed.
- Can hold different types of gene editing agents.
- Capable of carrying large agents like Cas9 for CRISPR therapies.
- The viral scaffold is customizable to better target specific cell types.
- Less chance of off-target gene editing.
Challenges Being Addressed:
- Safety profile and immune system activation are still being characterized.
Gene editing delivery methods are the subject of continuous research, and many scientists are finding innovative ways to bypass the limitations of individual technologies. As we search relentlessly for the right gene editing tools, we are also thinking about the best methods of delivery so that we can make the most effective and safe treatment for KAND.
Lab-grown ‘Mini-kidneys’ Unlock Secrets of a Rare Disease
One challenge in rare disease research is understanding which cells are responsible for dysfunction. Cells exist as interdependent communities to make up tissues and organs, and it can be difficult to know how mutations in a single gene impact different cell types.
Researchers from the University of Ottawa tackled this problem in tuberous sclerosis complex, which can cause tumors and fatal kidney dysfunction, and is caused by mutations in the TSC1 and TSC2 genes. The tumors are complex and the cells that start tumor formation were unknown. Researchers grew human stem cells into 3D mini-kidneys known as organoids, and introduced TSC1/2 mutations, and found that while these mutations impacted the development of a wide variety of cells, mutant Schwann Cell Precursor Cells were the start of tumor formation.
Organoids are an amazing development in disease research, including for KAND. Our Research Network members Drs. John Christodolou, Wendy Gold, and Simran Kaur are working with brain organoids carrying KIF1A mutations to better understand the disease and potential treatments.