Biodegradable Nanoparticles Target Brain Cancer Cells

The future of cancer treatment will be based upon a wide range of methodologies that selectively target cancer cells to deliver payloads that destroy only those cells. The end result will be highly effective treatments that can eliminate even metastatic cancer with minimal side effects. Here is an example of work in progress:

Biomedical engineers and neurosurgeons report that they have created tiny, biodegradable "nanoparticles" able to carry DNA to brain cancer cells in mice. "In our experiments, our nanoparticles successfully delivered a test gene to brain cancer cells in mice, where it was then turned on. We now have evidence that these tiny Trojan horses will also be able to carry genes that selectively induce death in cancer cells, while leaving healthy cells healthy."

[The researchers produced] tiny, round particles made up of biodegradable plastic whose properties can be optimized for completing various medical missions. By varying the atoms within the plastic, the team can make particles that have different sizes, stabilities and affinities for water or oil. For this study, [they] created dozens of different types of particles and tested their ability to carry and deliver a test sequence of DNA - specifically a gene for a red or green glowing protein. By assessing the survival of the cells that engulf the particles and measuring the levels of red or green light that they emitted, the researchers determined which formulation of particles performed best, then tested that formulation in mice with human brain cancer derived from their patients.

They injected the particles directly into mice with an experimental human brain cancer, and into the brains of healthy mice for use as comparison. Surprisingly, healthy cells rarely produced the glowing proteins, even though the DNA-carrying particles were entering tumor cells and non-tumor cells in similar numbers. "This is exactly what one would want to see, cancer specificity, but we are still researching the mechanism that allows this to occur. We hope our continued experiments will shed light on this so that we can apply what we learn to other scenarios."

The particles can be freeze-dried and stored for at least two years without losing their effectiveness. "Nanoparticles that remain stable for such a long time allow us to make up formulations well in advance and in large batches. This makes them easy to use consistently in experiments and surgeries; we add water to the particles, and they're good to go."



The researchers say they don't know what the actual mechanism is that allows the DNA to be expressed in cancer cells but not in normal cells, but hopefully it is not something that cancer cells will find it easy to mutate around.

With my layman's knowledge I know that cancer treatments can be specific to cancer cells by targeting a cell surface marker that appears only on cancer cells. But cancer cells can just mutate and some will no longer express this marker. Treatments that enter pretty much any cell target biochemical pathways within the cells, but most/all of these have redundant pathways and some will already have switched via mutation.

But perhaps this is targeting cancer where it is weak - control of gene expression. Maybe cancer cells are different to normal cells not just through constant growth and lack of mutation control, but also through genetic expression incontinence?

Posted by: Jim at April 30th, 2014 7:44 PM

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