Description
Background: Patients with biallelic mutations in RLBP1 gene develop a spectrum of autosomal recessive rod-cone dystrophies, for which there are currently no approved treatments. RLBP1 encodes cellular retinaldehyde binding protein 1 (CRALBP), a 36-kD protein that regenerates the visual chromophore 11-cis retinal. In this study, we aimed to assess the efficacy of RLBP1-mRNA therapy introduced to a patient induced pluripotent stem cell (iPSC) derived RPE using lipid-based nanoparticles (LNP).
Methods: Fibroblasts from one patient harbouring compound heterozygous variants in RLBP1 c.250del p.(Val84Trpfs*35) and c.361C>T p.(Arg121Trp) were isolated and cultured. RLBP1 and control iPSC-RPE lines were generated by reprogramming and subsequent differentiation. RLBP1-mRNA was transfected to RPE cells with a LNP, and CRALBP protein expression was assessed.
Results: mRNA coupled with LNP was successfully delivered to iPSC-derived mature and polarized RPE cells. CRALBP was not detected in untreated patient RPE cells, but expression levels after RLBP1-mRNA transfection reached ~30-50% compared to control RPE cells.
Conclusions: RLBP1-mRNA-LNP treatment rescues the missing protein in patient cells, making it a promising therapeutic option for individuals carrying variants in the RLBP1 gene. The next step will be to assess the function of the produced CRALBP protein by measuring 11-cis retinal production following transfection.
Lay Abstract
RLBP1-retinal dystrophy is a rare inherited, slowly progressive disease caused by faulty RLBP1 gene. Patients experience vision loss, classically starting with night blindness during childhood. RLBP1 gene carries the instructions to produce a protein essential for the recycling of visual pigments in the retina. Patients with a faulty RLBP1 gene do not produce the protein, therefore retinal cells cannot carry on with the visual cycle. We aimed to develop a therapeutic approach to patients with RLBP1 gene defects that targets the root cause of the disease. We used tiny fat droplets called lipid-nanoparticles to package a healthy copy of RLBP1 achieving a successful production of the missing protein into the retinal cells.
From a skin biopsy we isolated skin cells from a patient, transformed them into stem cells and guided them to become specialized retinal cells. After the treatment with the genetic material shielded by the tiny fat droplets, the patient’s cells produced the protein reaching 30 to 50% levels compared to healthy retinal cells. These results are encouraging for the development of a therapy for patients with defects in RLBP1 gene. Our next step is to check that the new protein carries out its functions in the patient’s cells.
| Lay Title | Developing a therapy for RLBP1-retinopathy |
|---|---|
| Role | Postdoctoral Researcher |