University of Birmingham phototherapy aids recovery from mild traumatic brain injury

16 Oct 2024

Study finds particular IR wavelengths improve outcomes and promote regeneration.

"Mild traumatic brain injury (mTBI) is a common consequence of head injury, but there are no recognized interventions to promote recovery of the brain."

So commented a University of Birmingham team investigating whether irradiation with light of different wavelengths might act as a valuable therapeutic technique for these kinds of injuries.

Usually a mTBI results when the initial trauma of head injury is magnified by a complex set of inflammatory changes that occur in the brain. These secondary processes, which take place from minutes to hours after head injury, can dramatically worsen outcomes for patients.

In a study published in Bioengineering & Translational Medicine, the project tested the ability of infrared light to protect against this secondary damage and stimulate faster, better recovery for patients.

Similar photobiomodulation (PBM) techniques are known to have potentially dramatic impacts on how biological tissues recover from injury or damage. A key part of the cellular electron transport chain is able to absorb light energy, promoting a number of beneficial downstream changes to oxidative stress and inflammation.

Practical uses of PBM have included University of Buffalo projects investigating how low-light therapy can enhance recovery from skin burns, reduce inflammation, or act as a palliative for mouth cancers.

The University of Birmingham has previously studied the ways that TBI can be detected in the retina of the eye before other symptoms manifest themselves, using a combination of Raman spectroscopy and fundus imaging.

Translation to clinical regeneration therapy

In the new study, treatment of mTBI using near-IR light at 660 and 810 nanometers was assessed, to see what effect PBM at those wavelengths has on recovery following injury.

After using ex vivo tissue samples to determine what delivery parameters allowed PBM to effectively reach the cortical surface, the project applied the two wavelengths to rat subjects and examined the effects after an induced mTBI. The pre-clinical study used daily two-minute bursts of infrared light, delivered by a laser, for three days post-injury.

Examination showed significant reductions in the activation of astrocytes and microglial cells, which are heavily implicated in the inflammatory processes in the brain that follow head trauma. Distinct reductions in biochemical markers of apoptosis or cell death were also seen, commented the Birmingham project.

"At four weeks, there were significant improvements in performance in functional tests involving balance and cognitive function," said the team. "The red light therapy also accelerated recovery compared to controls, with superior outcomes for light with a wavelength of 810 nanometers."

The method has now been patented by the university, which is seeking commercial partners to develop an instrumental platform suitable for clinical translation and use in regeneration therapy.

"We want to develop this method into a medical device that can be used to enhance recovery for patients with traumatic brain or spinal cord injury, with the aim of improving outcomes for patients," commented Zubair Ahmed from Birmingham's Centre for Trauma Sciences Research.