Loss of smell is a common side-effect of Covid-19. Around 1-in-5 Covid patients report a loss of smell eight weeks after being infected. Now an innovative method of restoring smell to patients is being tested using a patient’s own blood plasma.
Several methods of restoring Covid patients’ smell have been trialled so far, including smell retraining therapy, in which patients sniff strong smells several times a day. This form of smell retraining lasts for a few months, however, so far it only restores about 35 percent of a person’s smell. This is the gold standard of recovering sense of smell, according to otolaryngologist, David Rosen. Clearly an alternative with better results is needed. This is where plasma therapy comes in.
Platelet-rich plasma therapy has actually been around for 40 years. This treatment works by encouraging neurons called olfactory neurons, which are located in the nose, to repair themselves. The olfactory neurons detect information about scents and send signals to the central nervous system. According to Dr Rosen olfactory neurons are the only ones that can repair themselves:
“If a nerve that goes to the finger and allows it to move gets cut, it probably won’t work again if we put it back together because these nerves can’t regenerate very well. But we can regenerate olfactory neurons by jumpstarting the body’s own ability to repair itself with plasma.” Rosen explains.
Blood plasma is filled with platelets, which encourage the body to produce more stem cells, and these stem cells are able to create neurons.
“Platelets have a lot of growth factors that tell the body, “okay, start making stem cells and start differentiating those into neurons.” Damaged neural tissue is not easy to repair, but in this instance, we get away with it because of the neuroplasticity already in this system.”
The treatment involves taking a cellulose widget and soaking it in the patient’s plasma-rich blood, and inserting it far up the nose, where the olfactory neurons reside. Eighty percent of the plasma is absorbed in the first minute, and the widget falls out within a day or two.
Dr Rosen is now in Stage 2 of clinical trials. Whilst not yet published as research, he says that two dozen patients have already completely regained their sense of smell using plasma therapy. The next step is a double-blind study. Whilst this therapy is still in the early stages of clinical trials, the patients he has treated may give hope to others:
“I saw a patient yesterday who had only received two treatments so far, and she told me that grass smelled like grass to her again and chocolate tasted like chocolate. I’m excited to see people getting back to their normal lives.”