ProtoKinetix updated shareholders regarding ongoing third stage testing of retinal cell replacement therapy at the University of British Columbia. As previously reported, the company demonstrated the ability of AAGP to protect transplanted cells in a preclinical experimental model of retinal degeneration. For the purpose of these tests, the animals had a functioning immune system and were treated with immune modulating drugs to model clinical practices. The results demonstrated the ability of AAGP to protect the delicate transplanted cells from the stress of the local microenvironment after transplant into the recipient at the 4-week timepoint, according to a ProtoKinetix news release.
Two questions under study have been answered:
- Do the transplanted cells survive in the recipient and safely continue to mature into functional retinal cells?
- Does AAGP interfere with the fated development of the transplanted cells?
In order to answer these questions, a comprehensive series of tests using immune suppressed animal models were designed. These tests included a long-term follow-up out to 6 months to determine if the cells continued to mature into photo-sensitive cells and whether the presence of AAGP interfered with this essential development. At the 5-month timepoint, the tests show that AAGP preserved and allowed these cells to mature without compromise.
Pluripotent stem-cell therapy guided into retinal cells could potentially cure blindness even in the late stages of disease. However, until now, studies in animals have shown that too few transplanted retinal cells survive the hostile local environment long enough to integrate correctly into the retina’s complex neural circuitry. The AAGP molecule in this study has overcome this considerable obstacle for stem-cell treatments that aim to replace retinal cells.
These studies are a critical component of the preclinical testing required to advance this program into clinical trials. The study is being conducted by the Gregory-Evans Retinal Therapeutic Lab at the University of British Columbia.
“We are now completing functional studies in two different animal models. These include electrical responses of the eye and also a behavioral test of sharpness of vision,” Kevin Gregory-Evans, FRCOphth, MD, PhD, Professor of Ophthalmology in the Faculty of Medicine, University of British Columbia, said in a company news release. “Preliminary results show retention of vision function particularly in behavioral testing in the rodent model. Also, of note, we have not documented any adverse effects in animals when using AAGP. Although our results are in relatively small numbers of animals (a dozen in each cohort of testing) this bodes exceptionally well for any proposed future clinical trial work.”