When Cells Become the Medicine: The Rise of Living Drug Delivery

Getting a medication to the right place in the body is often more difficult than simply developing the drug itself. Conventional drug-delivery systems, including nanoparticles, can face challenges such as limited targeting and rapid removal from the body.

Researchers are exploring a different approach: using living cells as therapeutic delivery vehicles. Rather than acting as passive containers, these cells can naturally interact with their surroundings, remain in circulation, and sometimes travel toward specific tissues. This has led scientists to investigate whether cells could serve as “living drugs” capable of transporting therapeutic molecules directly where they are needed.

---

Why Use Living Cells?

Cells possess several properties that make them appealing drug-delivery platforms. They are naturally compatible with the body, can persist for extended periods, and may be able to navigate biological barriers that are difficult for synthetic systems to cross.

Scientists can also modify certain cells to carry therapeutic substances. Depending on the cell type, treatments may involve loading drugs inside the cell, attaching therapeutic molecules to its surface, or genetically engineering the cell to produce a desired therapeutic agent. This creates the possibility of combining the natural behaviour of a cell with the precision of modern medicine.

Red Blood Cells: More Than Oxygen Carriers

Red blood cells (RBCs) are being investigated as potential transport systems for therapeutic molecules. Because they circulate throughout the bloodstream for relatively long periods and lack a nucleus, they offer an unusual platform for drug delivery.

Researchers can introduce certain therapeutic compounds into RBCs, allowing them to act as temporary carriers. In some approaches, a drug precursor is loaded into the cell and gradually converted into its active form, potentially allowing the treatment to be released over an extended period.

RBC surfaces can also be modified to carry therapeutic molecules or recognize specific targets. This raises the possibility of using the body's own circulating cells to improve how treatments move through the body.

Platelets: Targeting Sites of Injury and Disease

Platelets offer another intriguing delivery strategy because of their natural role in responding to damaged tissues. Scientists have explored whether this behaviour could be redirected to deliver treatments.

For example, researchers have investigated loading anti-cancer drugs into platelets so that the therapeutic cargo can be released when the platelets become activated. Other approaches involve engineering platelet-producing cells so that the resulting platelets carry therapeutic proteins or molecules.

Because platelets naturally interact with injured tissues and can associate with tumour cells, their biological behaviour may provide opportunities for more targeted treatment.

Stem Cells as Therapeutic Couriers

Mesenchymal stem cells (MSCs) are another promising candidate. These cells are particularly interesting because they can influence their surrounding environment by releasing signalling molecules involved in inflammation, immune regulation, blood-vessel formation, and tissue repair.

Researchers are also investigating genetically modified MSCs as potential delivery systems for cancer treatment. Their ability to migrate toward certain tumours, including brain tumours, makes them attractive candidates for transporting therapeutic molecules to locations that are otherwise difficult to reach.

The Future of "Living Drugs"

The concept of cellular drug delivery represents a shift in how scientists think about medicine. Instead of designing a treatment that simply travels through the body on its own, researchers can potentially use the biological abilities of cells to help guide, protect, and release therapeutics.

References

1. Bush, L. M., Healy, C. P., Javdan, S. B., Emmons, J. C., & Deans, T. L. (2021). Biological Cells as Therapeutic Delivery Vehicles. Trends in pharmacological sciences, 42(2), 106–118. https://doi.org/10.1016/j.tips.2020.11.008

Assessed and Endorsed by the MedReport Medical Review Board