Rinri Therapeutics, a biotech company born from years of academic research at the University of Sheffield, has been granted approval to begin the world’s first human trial of a cell therapy designed to restore hearing by repairing the auditory nerve itself. Called Rincell-1, the treatment aims to regenerate nerve cells in the inner ear that are essential for transmitting sound signals to the brain—cells that no current treatment can replace.

A New Approach to Hearing Loss

Most people are familiar with hearing loss that comes from damaged hair cells in the inner ear. But in neural hearing loss—seen in conditions like age-related hearing decline (presbycusis) and auditory neuropathy spectrum disorder (ANSD)—the issue lies deeper, in the nerve fibers that connect the ear to the brain. Cochlear implants can help, but only if the auditory nerve is still functional.

Rincell-1 offers something radically new. It uses lab-grown precursor cells—called otic neural progenitor cells—that are designed to mature into working auditory neurons after being delivered directly into the cochlea during cochlear implant surgery. In essence, it’s like rewiring a frayed cable at its core, not just boosting the signal.

“Instead of just amplifying or rerouting sound, we’re aiming to rebuild the broken connection,” said Professor Marcelo Rivolta, the therapy’s lead scientist and co-founder of Rinri Therapeutics.

Trial Details: Who’s In and What’s Next

The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has approved a Phase I/IIa trial, which will be conducted at three of the country’s top hearing research centers. The trial will involve 20 adult participants: ten diagnosed with auditory neuropathy spectrum disorder (ANSD) and ten with advanced age-related hearing loss. In each group, half will receive both a cochlear implant and the experimental treatment, Rincell-1, while the rest will be fitted with the implant only.

This isn’t just about seeing whether the treatment works—it’s first about safety. But researchers will also be looking for early signs that the therapy helps regenerate nerve activity. They’ll use real-time data from a monitoring system built into the cochlear implants, as well as speech perception tests and patient feedback.

Within a year of starting, the team expects to gather proof-of-concept data—an early indicator of whether this therapy could become a viable treatment.

Opening a Door Previously Sealed Shut

The auditory nerve endings are buried deep within the skull, protected by bone and difficult to reach. Traditional surgery would require extensive drilling—something too risky and painful for a routine procedure.

Now, thanks to collaborative research across universities in the UK, Canada, and Sweden, a less invasive method has been developed. Described in Nature Scientific Reports, the new approach uses a natural membrane in the inner ear called the round window as a gateway. Through this access point, surgeons can deliver the regenerative cells directly to the site of damage with far less trauma.

“It’s like slipping a message through a mail slot instead of breaking down the front door,” said Professor Doug Hartley, Rinri’s Chief Medical Officer and one of the architects of the new procedure.

Why This Trial Matters

Neural hearing loss impacts more than 100 million people globally, and that number is projected to grow as populations age. Yet treatments have lagged behind, partly because regenerating nerve tissue in the ear was once considered impossible. Rincell-1 is the first attempt to not just manage symptoms but actually change the trajectory of the disease.

The therapy was developed using Rinri’s OSPREY™ platform—a method for producing ready-to-use cell therapies that don’t rely on patient-specific donor cells. That means, if successful, Rincell-1 could one day be available “off-the-shelf,” making it more accessible and affordable than personalized regenerative therapies.

For now, all eyes are on this first trial. It’s the scientific equivalent of planting a seed in long-frozen soil—no guarantees, but a real chance that something once thought lost could grow again.

[Source: 1,2]

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Dental Pulp Cells Can Repair Tissues Beyond the Mouth

Scientists around the world are culturing and testing dental pulp cells in the lab. At CSIRO’s Stem Cell Centre in Australia, for instance, researchers examine cultured stem‑cell samples under high‑resolution microscopes.

In the lab, DPSCs self‑renew and proliferate rapidly. Studies show that when given the right signals, DPSCs will lay down collagen and calcium to form bone or cartilage matrix and even beat and contract like muscle.

Compared with bone‑marrow stem cells, DPSCs often build mineralized (bone) tissue more quickly. In engineered joint grafts they can produce cartilage tissue in vitro. In one animal study, combining human dental pulp cells with a scaffold led to significantly more new bone growth than a scaffold alone.

Such findings give hope that wisdom‑tooth cells could one day aid in healing fractures, repairing jawbones after tumor surgery, or rebuilding degenerated cartilage in arthritic joints. Each year millions of wisdom teeth are removed and usually discarded. In the United States alone an estimated ten million molars are extracted annually.

Tooth Banking and the Future of Personalized Medicine

A growing number of biotech startups and dental clinics now offer “tooth banking” – preserving a patient’s pulp cells for possible future use. The process of collecting dental pulp stem cells begins immediately after the tooth is removed.

The extracted wisdom tooth is placed in a sterile container and transported under cold conditions to a laboratory. There, specialists extract the pulp tissue and typically freeze the stem cells within a day to preserve their viability.

Proponents note that banking one’s own DPSCs eliminates concerns about immune rejection later, and the upfront cost (comparable to cord‑blood banking) could pay off if personalized therapies are needed decades down the line.

Clinics partner with oral surgeons to harvest molars that would otherwise be discarded, turning “trash” into a long‑term biological asset. Early experiments hint at a wide range of potential therapies.

For example, cardiologists have tested injections of dental‑pulp cell secretions in rodents with heart failure, and observed improved cardiac function – suggesting that a patient’s own wisdom‑tooth cells might one day help mend a damaged heart.

In neurological studies, DPSC transplants into Alzheimer’s‑model mice produced measurable improvements in memory and brain pathology.

It can generate dopamine‑producing neurons in culture, and rodent models of Parkinson’s disease showed motor improvements with dental stem cell therapy.

DPSCs appear to secrete a cocktail of growth factors that protect nerves, reduce inflammation and even help clear toxic proteins in the brain. Outside the nervous system, laboratories report that dental pulp cells readily become osteoblast‑like and build bone in 3D scaffolds, making them promising for filling bone defects.

More Work Is Needed to Prove Safety and Efficacy

As the evidence grows, investigators are planning clinical trials of dental pulp therapies. Early stem‑cell implants (using embryonic stem cells) in Parkinson’s patients have already demonstrated that new dopamine neurons can survive and function in humans. Using DPSCs instead could avoid ethical controversies and reduce immune risk.

However, experts caution that more work is needed. Transplanted cells must be shown safe (without forming tumors) and effective in people. Scientists at universities and institutes worldwide – for example at the University of the Basque Country in Spain – continue refining protocols to turn tooth pulp into therapy. “These are easily accessible human stem cells for nerve tissue engineering,” researchers note.

They argue that routinely preserving wisdom teeth now could create a personalized “biobank” of one’s own stem cells, offering future regenerative treatments without the wait for a perfect donor match. Wisdom teeth may have been viewed as nuisances, but modern research is recasting them as biological treasure.

Before tossing those extracted molars, patients might consider the hidden value inside. In the coming years, therapies for bone injuries, neurological diseases or heart disease may indeed spring from the “medical gold” locked in wisdom tooth pulp.

[Source: 1,2]

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In their study, scientists applied this new material to the damaged knee cartilage of the animals. Over a six-month period, they observed substantial improvements, with the material facilitating the growth of new cartilage. This newly formed cartilage was rich in essential biopolymers such as collagen II and proteoglycans, which are vital for maintaining the strength and pain-free function of joints.

“Our new therapy offers the possibility to repair tissues that otherwise lack the ability to regenerate on their own. We believe this treatment could address a significant unmet need in clinical practice,” said Samuel I. Stupp, the lead researcher from Northwestern.

Though the material may resemble a rubbery substance, it is actually a sophisticated network of molecular components that closely mimics the natural environment of cartilage in the body.

“Cartilage is crucial for joint function, and when it becomes damaged or deteriorates over time, it significantly impacts overall health and mobility,” Stupp explained. “Unfortunately, adult cartilage does not naturally regenerate, which makes our approach so valuable.”

This breakthrough builds upon previous work by Stupp’s team, where they used “dancing molecules” to encourage human cartilage cells to produce more tissue matrix proteins. In contrast, the current study introduces a hybrid biomaterial composed of two key elements: a bioactive peptide that binds to transforming growth factor beta-1 (TGFb-1), a critical protein for cartilage growth, and modified hyaluronic acid, a natural polymer found in cartilage and joint fluid.

Stupp’s team created this biomaterial by combining bioactive peptides with chemically modified hyaluronic acid, forming nanoscale fiber bundles that replicate the structure of natural cartilage. This scaffold attracts the body’s cells to promote cartilage regeneration, and the bioactive signals embedded within the material encourage cells to populate the scaffold and repair the damaged tissue.

“Many people know hyaluronic acid from skincare products, but it’s also a key component found naturally in various tissues throughout the body, including joints,” Stupp noted. “We selected it because it closely resembles the natural polymers found in cartilage.”

To test its effectiveness, the researchers applied the material to cartilage defects in the knee joints of sheep, which share similar structure and mechanical load with human knees. When injected as a thick paste, the material created a rubbery structure within the joints, encouraging the growth of robust cartilage as the scaffold slowly broke down.

Looking to the future, Stupp envisions this material being used in joint surgeries, including both open-joint and arthroscopic procedures. Currently, microfracture surgery is the standard approach, where small fractures are made in the bone to stimulate cartilage growth.

However, with further development, this new biomaterial could offer a superior alternative. It has the potential to prevent the need for full knee replacements, treat conditions like osteoarthritis, and even repair injuries such as ACL tears, offering a long-term solution that could improve patient outcomes and quality of life.

References:

Northwestern University (2024). “New biomaterial regrows damaged cartilage in joints.” Available at: https://news.northwestern.edu/stories/2024/august/new-biomaterial-regrows-damaged-cartilage-in-joints

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