Osteoarthritis, which results when the cartilage and bone in the body’s joints wears down from stress, often causes swelling, stiffness, chronic pain and difficulty in walking. The condition is widespread in India; a scientific paper from 2016 estimated that between 22 and 39 percent of the country’s population suffers from it.
There is no cure for osteoarthritis, though doctors recommend various treatment regimens, from lifestyle changes to joint-replacement surgeries. A lab in Assam is currently researching what may become a sophisticated new treatment for the condition—a silk-based tissue implant. Biman B Mandal, an associate professor in biosciences and bioengineering at IIT Guwahati, along with Jonathan Knowles, a professor at University College London, have developed a technology to synthesise mats made of silk proteins and bioactive glass fibres, creating a tissue substitute which, they think, will regrow patients’ bone and cartilage cells and repair their worn-out joints.
In January, I met Mandal in his lab—three large rooms housing an eclectic array of machines, from a fluorescent microscope to a 3D bioprinter. It was after 8 pm, but the lab’s researchers, wearing white coats, were still hard at work.
Mandal began working with silk on bioengineering projects because he knew the material was often used, to great success, for sutures in surgery. The scientists in his lab, he explained to me, create the silk-based implants by reconstructing “the scaffold of the template where different kinds of cells can be grown and regrown.” This method produces an implant highly similar to natural tissue, “mimicking the implantation site” and allowing it to fit well on a patient’s joint.
Joseph Christakiran Moses, a PhD student who works in Mandal’s lab, told me that the silk they use is procured from local farms in the nearby city of Mangaldoi. They use muga silk—a world-renowned variety that has a geographical-indication designation, prohibiting any silk produced outside Assam from being called by that name. Sometimes, Moses and other researchers go to Mangaldoi themselves to collect silk cocoons.
The scientists use muga silk because it contains basic proteins that encourage cell adhesion, migration and proliferation, helping the tissue substitute stay effective. Another PhD student who works in Mandal’s lab, Yogendra Pratap Singh, showed me how they start the silk-production process by boiling silk cocoons, then extracting silk fibres from the resultant mixture. These fibres are further processed into a pure silk solution, and then turned into ultra-thin fibres using electrospinning—a technique in which the solution is injected through an electrically charged needle.
The scientists then use the fibres to build the implants, which are called composite mats. These mats are “grafted in the defected joint with cells harvested from the patient,” and eventually “bond with the patient’s tissue and act as an artificial tissue construct,” Joseph said. With time, Singh added, the “artificial bone silk tissue graft degrades and new tissue is formed in its place.”
Paying attention to the interface between bone and cartilage is crucial. In the past, Mandal told me, scientists generally looked at the replacement of cartilage and the replacement of bone as separate matters, without enough consideration for the connections between the two. “If the interface is not mimicked properly, the fabricated material for the implant developed will not be as efficient as we want,” he said.
Mandal hopes that in the future, such implants will be able to be inserted during a minor surgery. The implants are intended for cases of middle- and late-stage osteoarthritis, in which patients’ joints are either partially or totally damaged.
The scientists conducted successful laboratory tests of the silk-based tissue implants between 2015 and 2016. Next, Mandal told me, they “are planning for animal experiments to take this technology forward.” But the process of getting regulatory clearance for such testing, he said, “is time-taking and stringent.” Only if those future tests are successful will the implants move on to randomised human trials—and after that, perhaps, to the market.
The scientists’ successes come with pressure, especially since many osteoarthritis patients are awaiting the lab’s new treatment. “I started receiving numerous phone calls from people whom I have never met,” Mandal said. “Suddenly we felt so much of responsibility on our shoulders. We felt as if everyone is eagerly watching us with very high expectations.”
Avantika Srivastava is a Bengaluru-based writer with a master’s in microbiology and a postgraduate diploma in journalism. She writes about science and lifestyle issues.