Inherited retinal disease (IRD) affects people of all ages around the world.

Within the spectrum of IRD, retinitis pigmentosa is reported to be one of the common causes of blindness.

It is a debilitating condition that affects the retina and its functional response to light, with approximately two million people diagnosed worldwide.

Patients that suffer from retinitis pigmentosa gradually succumb to complete vision loss as there is currently no cure for this condition, although various supportive therapies are available.

In recent years, there has been scientific interest in the use of stem cells for the treatment of retinitis pigmentosa, including in Malaysia.

A phase I clinical study using Wharton's jelly-derived mesenchymal stem cells was carried out on two local patients – a 65-year-old man and a 57-year-old woman, who have both had the condition for over 20 years – starting in November 2020.

Mesenchymal stem cells are multipotent stem cells with self-renewing capacities and are able to differentiate into multiple cell types such as fat cells, cartilage cells, bone cells, muscle cells and more.

They also contain immunomodulatory properties and paracrine effects, which can potentially restore photoreceptor cells, i.e. the cells that are responsible for the ability to see.

In retinitis pigmentosa, there is a significant loss of these cells, which leads to permanent loss of vision.

In the study, which was published in the Medical Journal of Malaysia last September (2022), the mesenchymal stem cells were injected into an area known as the subtenon space, deep within the eye cavity.

After four injections and a year of follow-up, both patients did not suffer any further deterioration to their vision and visual field, nor did they experience any adverse side effects from the injections.

Says co-lead investigator Datuk Dr Nor Shahidah Khairullah: “Our report indicates one patient showed the ability to identify and appreciate colours that he was not able to distinguish previously.

"After treatment, both patients can now enjoy the colourful world with more definitive brightness, improvement in vision precision on estimated distance and incoming vehicles in real road conditions, and clearer vision, especially during first half of the day.”

Co-lead investigator Angelina Tiah notes that the promising results of this initial study allows them to now move into phase 2 clinical trials for this treatment.

Phase 2 clinical trials involve a larger group of patients, and further tests the safety and effectiveness of a particular treatment.

Tiah is the chief scientist at local biopharmaceutical company Cellaax Therapy, while Dr Nor Shahidah is the company's medical advisor.

The treatments were administered by Hospital Shah Alam Department of Ophthalmology head and consultant ophthalmologist Datuk Dr Nor Fariza Ngah, and her colleague, consultant ophthalmologist Dr Roslin Azni Abdul Aziz.