By Dana Barberio
January 19, 2017 | What if a doctor could simultaneously and rapidly test multiple chemotherapeutic agents inside your body for effectiveness against your tumor? Or introduce a nano-sized protein factory into your body to produce proteins on demand? How about inserting nanoparticle cushioning into your joints to relieve your osteoarthritis?
These diverse techniques all require nano-sized liposomes—vesicles composed of a lipid bilayer surrounding an inner aqueous core—and clinically approved drug carriers, as reviewed in the October 2014 Nature Reviews Drug Discovery (doi:10.1038/nrd4333). Avi Schroeder, a professor of chemical engineering at Technion Israel Institute of Technology, has found that 100 nm liposomes can accumulate preferentially in solid tumors after being injected intravenously, suggesting intriguing diagnostic and therapeutic applications.
Nanoparticles and Tiny Barcodes for Therapeutic Treatment Selection
In a powerful combination of precision medicine and nanotechnology, researchers led by Avi Schroeder, now a professor of chemical engineering at Technion Israel Institute of Technology, were able to screen anticancer drugs inside the tumors of mice for their therapeutic potency, as reported in the November 10, 2016 Nature Communications (doi:10.1038/ncomms13325).
Using their patented technology, 100 nanometer liposomes were loaded with minuscule amounts of chemotherapeutics and synthetic DNA strands, or “barcodes,” that identify the therapeutics. The nanoparticles were injected into tumor-bearing mice, and the drug-filled liposomes then accumulated preferentially in solid tumors. By analyzing the DNA barcodes associated with the chemotherapeutics, the researchers were able to correlate the viability of the cells (live or dead) with the drug they were exposed to.
This technology was inspired by allergy tests, in which tiny quantities of allergens are injected under the skin, Schroeder tells Diagnostics World News. Allergy tests screen for activity of agents inside a patient’s body, eliciting a response on the skin. However, with this novel nanotechnology, the response to chemotherapeutic agents is inside the patient’s tumor, providing physicians with another level of information in making therapeutic choices.
A huge benefit lies in the speed of the procedure, which takes only 72 hours. “An alternative to this technology is to take a biopsy and grow [cells] in Petri dishes, and then in the cell culture screen different medicines against the patient-derived cells. This takes 4-6 weeks,” said Schroeder. “For many patients, if there is a high rate of genetic alteration with mutations in the tumor, you’re going to be treating a tumor that [is totally different] in the patient.” At best, the current state of the art is 1 week to look at the patient’s tissue and decide which medicine is appropriate, said Schroeder. Another benefit to using the DNA barcoding technique is that it provides extremely sensitive detection, with unlimited barcoding possibilities, explains Schroeder. “We hope to give physicians a new tool in personalized cancer care,” said Schroeder.
The researchers used 50-150 base-pair long double-stranded DNA to create barcoded nanoparticles. Using tumor-bearing mice (with triple-negative breast cancer xenografts), the researchers intravenously injected liposomes carrying a cocktail of five of these barcoded nanoparticles along with their associated chemotherapeutic (cisplatin, doxorubicin, and gemcitabine) or control. The tumors were biopsied 48 hours later and cells were sorted by FACS based on cell viability (live/dead). Live and dead cells were collected separately and the DNA barcodes were extracted, amplified by RT-PCR and then sequenced. Barcodes found in dead cells were an indication of active drugs, and those found in live cells, non-active drugs. Cisplatin, doxorubicin and gemcitabine all had a greater positive therapeutic effect as compared to the controls. Based on the barcode distribution, gemcitabine appeared to be the most efficient drug. It was also found to accumulate 30,000 times more in the dead cells than in the live cells. The control actually accumulated 3,000 times more in the live cells than in the dead cells.
“What we really want to do now is translate this technology to the clinic. Our main goal is to start with triple negative breast cancer, move on to other types of breast cancer, followed by other types of cancer,” said Schroeder.
Nanoparticles to Reduce Cartilage Breakdown
Similar nanoparticle liposomes have been engineered to be beneficial even without the chemotherapeutic and DNA barcode payload.
In another patented nanotechnology application, further along in Phase II in the clinic, Schroeder and researchers at Sun Pharma are using nano-sized water-filled liposomes as a new type of biomaterial for reducing cartilage’ friction and wear and to enable its regeneration. “You can envision them as small ball bearings inserted between the joints to reduce friction and wear in cartilage,” said Schroeder. The researchers engineered a lipid bilayer soft enough to act as a cushion, reducing cartilage degradation, but also rigid enough to not fall apart in the joint under the body’s weight. “Much like a mattress in a semi-good hotel. You don’t fall in and it supports you,” said Schroeder. They have Phase IIA data showing that the quality of life of osteoarthritis patients was restored after treatment. Results were far better than hyaluronic acid, explained Schroeder.
Remotely Activated Protein-Producing Nanoparticles
In another application led by Schroeder, nanoparticles are being developed for use in generating proteins on demand inside the body.
While doing postdoctoral work in Robert Langer’s lab at MIT, Schroeder led researchers in developing a patented nanoparticle application, remotely activated protein-producing nanoparticles. (Nano Letters, March 2012 doi: 10.1021/nl2036047).
“Instead of using a drug delivery system with a drug inside of it, you introduce particles that contain a small factory that is capable of producing a protein of interest,” said Schroeder. The nanoparticles consist of lipid vesicles filled with the cellular machinery, including ribosomes, amino acids, etc., responsible for producing RNA and then protein inside the body. “We added a cage molecule to the DNA, which is like a switch, so once you irradiate with light of a particular wavelength, you get the production of protein (medicine) onsite,” said Schroeder. Using this method, the researchers were able to inject these particles locally into mice and remotely activate with light to produce luciferase in vivo. “This will be more of a system used for research. A factory travelling around your body,” said Schroeder.
It will be exciting to watch the progression of these experimental nanotechnologies and their contribution in the advancement of novel diagnostic and therapeutic applications. Stay tuned!