The new cell therapy, recently described in the journal Stem Cells, accelerated the recovery of ruptured Achilles tendons in a rodent model, and may similarly aid other healing tissues, shortening the time until these structures regain functional strength.

The research team is now working to obtain FDA approval for a first human clinical trial to treat devastating injuries in musculoskeletal tissues.

The therapy works, says Ray Vanderby, professor of biomedical engineering and orthopedics and rehabilitation at UW–Madison, by using a particular cell type, called a macrophage, to orchestrate an improved wound-healing cascade. Macrophages have been implicated in the body’s inflammatory response, in limiting tissue damage, in promoting tissue repair and more.

To make these therapeutic macrophages, researchers expose a patient’s own macrophages to signaling factors from mesenchymal stromal cells, a cell type that exhibits stem cell-like qualities in that they give rise to several other types of cells, such as bone and muscle cells.

In the study, adding these specialized “exosome-educated macrophages” to healing Achilles tendons in rodents reduced scar tissue formation and accelerated functional recovery.

“In pre-clinical models our new approach is more consistent and significantly better than normal healing or surgical repair with mesenchymal stromal cells added,” Vanderby, a principal investigator on the study, explains.

Though not tested in the study, the method could improve outcomes for many problematic clinical issues, such as rotator cuff and anterior cruciate ligament (ACL) reconstructions. These surgeries restrict normal activity and often keep patients out of sports for roughly a year.

Faster healing may shorten rehabilitation and hasten a return to normal activities and sports, and a shorter recovery could help reduce overall health care costs, though the study does not address this.

Because this technology uses a patient’s own cells, the researchers say they expect the first clinical trials to begin in the near future.

The research team includes Connie S. Chamberlain, from the Department of Orthopedics and Rehabilitation; Peiman Hematti, from the Department of Medicine, Division of Hematology/Oncology; John A. Kink, from the UW Carbone Cancer Center, and others at the UW–Madison School of Medicine and Public Health.

Chamberlain, a research scientist, recently won an award for presenting this work at the 2019 Orthopaedic Research Society Conference, and the team has submitted a patent application based on the technology, filed by the Wisconsin Alumni Research Foundation.

“Use of these specialized macrophages has attracted interest at national conventions and has shown great promise as a new cell-based therapy for musculoskeletal healing,” Chamberlain says.

In an effort to tip the balance toward the upsides of chemotherapy, Glen Kwon, a professor in the University of Wisconsin–Madison School of Pharmacy, is turning to nanoparticles capable of enhancing these drugs’ therapeutic properties.

In new work recently published in the journal ACS Nano, Kwon’s lab developed a stabilized form of a common chemotherapy agent, gemcitabine, and encased it in nanoparticles capable of slowing down their release. In mouse models of human lung cancer, the improved drug inhibited tumor growth more effectively than standard gemcitabine.

“There’s been a lot of hype about nanotechnology,” says Kwon, who has worked in the field for more than 20 years. “It’s an ambitious goal: to target drugs to particular places in our body.”

That goal may be some way off, Kwon says, but particles that ferry drugs into the body — known as nanocarriers — are already proving effective. “What nanocarriers can do is reduce toxicity,” he says.

In work with his graduate student Tony Tam two years ago, Kwon developed an improved system for delivering the chemotherapy drug paclitaxel, commonly sold as Taxol, during treatment. Tam attached a short chain of lactic acid to the drug, which helped it load into nanocarriers made, in part, of lactic acid. The nanocarrier has been used in humans before.

So when turning to gemcitabine, Tam tried the same tactic — add on chains of lactic acid and load it into the nanocarrier.

“But the first trial that we had was not stable at all,” says Tam, now a senior scientist at Merck in San Francisco. To increase the drug’s stability, he turned to 30-year-old work out of Japan.

In the 1980s, researchers at Kyoto University combined chains of lactic acid that were identical except for one key feature — their handedness. Many molecules come in mirror-image forms of themselves, and when the Japanese researchers combined left- and right-handed versions of lactic acid polymers, the resulting crystals, called stereocomplexes, were much more stable.

When Tam produced gemcitabine-linked stereocomplexes of lactic acid and loaded them into the nanocarrier, the drug’s stability spiked. Compared to gemcitabine attached only to the left-handed form of lactic acid, the stereocomplex released gemcitabine 15 times more slowly in an artificial solution. Since gemcitabine breaks down so quickly in the body, it’s usually given at high doses to make sure enough reaches the tumor. If this nanocarrier system slowed release in the body, it could mean gentler doses.

Curiously, the nanoparticles adopted an unexpected shape. While similar nanocarriers envelop drugs in a sphere, images taken at the atomic scale show the gemcitabine stereocomplexes adopting a stretched-out, cylindrical shape. You could stack 10,000 of these cylinders end-on-end within the thickness of a piece of paper.

Atomic-scale images of gemcitabine-loaded nanoparticles reveal an unusual cylindrical shape. Courtesy of Tony Tam

In mice harboring a human-derived non-small-cell lung cancer line, treatment with the stereocomplexed nanocarriers over three weeks kept the tumors from growing. In contrast, the tumors more than doubled in size in the mice treated with standard gemcitabine. The mice were treated at a fairly low dose to assess differences between the forms of gemcitabine.

“Ultimately our goal is to get this into human beings,” says Kwon, adding that many steps, such as scaling up production and preliminary safety studies, will be required.

With the Wisconsin Alumni Research Foundation, Kwon and Tam submitted a patent based on their modifications to gemcitabine that enhanced its stability and release. And Kwon co-founded Co-D Therapeutics, a preclinical stage company developing nanocarrier-based medicines based on his earlier work with paclitaxel.

“This research relied on really good teamwork in the School of Pharmacy community,” says Tam, noting that members of two other labs in the school contributed to the ACS Nano paper.

“Collaboration is very important.”

This work was supported in part by the National Institutes of Health (grant R01AI01157) and the National Science Foundation (award CHE-9974839).

Baseline PET scan shows uptake of manganese chloride tracer in mouse pancreas, in research at the University of Wisconsin-Madison department of radiology. Signal is greatly reduced in mice given a drug that inhibits insulin production, and conversely, intensified in mice given a stimulator of insulin production. Reinier Hernandez, UW-Madison

Researchers at the University of Wisconsin-Madison have developed a new measurement for the volume and activity of beta cells, the source of the sugar-regulating hormone insulin.

In a study published in the August edition of the journal Diabetes, Weibo Cai, Matthew J. Merrins and colleagues used a PET scanner to detect minute levels of a radioactive chemical in the mouse pancreas. Cai, the senior author of the study and an associate professor of radiology, says that unlike previous methods for measuring the quantity of beta cells, the new test also measures how actively these cells are making insulin.

PET scanning, or positron emission tomography, is used to detect minute quantities of tracers, commonly for finding cancer and metastases. This area is a specialty of Cai. Cai says the test may be used to evaluate treatments or cell transplants intended to slow or reverse diabetes.

With a provisional patent filed through the Wisconsin Alumni Research Foundation, Cai has begun planning a series of human trials that could lead to Food and Drug Administration clearance for a new method to determine the quantity and condition of the beta cells. The first step in these trials would look at the distribution and potential toxicity of the radioactive manganese chloride used as a tracer.

A shortage of insulin, due to the death or inactivity of the beta cells, causes type I (formerly “juvenile“) diabetes. The same problem can also cause type II diabetes. But this condition, once called “adult onset” diabetes, can also result from insufficient response to insulin. “In some conditions you can have an adequate number of beta cells, but not all of them are functioning,” says Cai. “We measure volume and get a product of function times volume, which is what everybody wants to know.”

The chosen tracer has a short half-life, so the exposure to radiation is no greater than what is now used in the many PET scans used to detect cancer.

“We don’t think there is another way to do this with this degree of accuracy.”

Weibo Cai

Because blood sugar tests are cheap and reliable, Cai is not proposing to replace them for detecting diabetes. Instead, the new test could be used to track the effectiveness of medicines and other measures intended to dampen the immune assault that kills beta cells.

The test could offer advantages over earlier methods to detect and analyze beta cells, Cai says. Some magnetic resonance techniques can give information about the quantity and function of beta cells, he says, but they use a dose of manganese chloride that is at least 1 million times higher than the new PET technique, suggesting an advantage in lower toxicity.

Other tests detect beta cells by identifying receptors that are unique to those cells, “but even if cells are not functioning, the receptors are still there,” Cai says, “so that does not tell you if they are making insulin. Our test is based on the calcium channel, a portal that the cell uses to exchange chemicals with its environment. The cell has to be active to take up manganese chloride, therefore it’s functioning, and if you have more functioning beta cells, then you have more insulin.”

Overall, Cai says, “We don’t think there is another way to do this with this degree of accuracy.”

The other authors included Matthew Merrins and Michelle Kimple, both assistant professors of medicine at UW–Madison who focus on diabetes research.  ‘This study, with 15 authors, highlights great collaboration between UW-Madison departments and faculty with distinct expertise,” says Cai.

The development of the new test is more proof that chance favors the prepared mind. First author Reinier Hernandez, who was Cai’s graduate student and is now a post-doctoral radiology researcher in Madison, and co-first author Stephen Graves, who is now a medical physics resident at University of Iowa, came up with the idea when they noticed high uptake of manganese chloride in the pancreas while exploring a PET tracer for cancer. Plenty of people saw apples fall from a tree, but at least according to legend, it was only Isaac Newton who was prompted to think deeply about gravity. “When the apple falls from the tree, you have to put out your hand to catch it,” Cai says. “Reinier and Stephen did. Another person might have missed it.”

Preparation played a second crucial role in the story, adds Cai. “People knew that manganese chloride uptakes in the beta cells, but nobody could make radioisotopes that were pure enough. But Jerry Nickles and Jonathan Engle [the past and present directors of the campus PET Cyclotron Laboratory] are the best in the world at making chemically pure manganese chloride with determined radiological activity. So we were only ones able to pull this off.”