Retinitis Pigmentosa (RP) clinical trials

Investigation of Therapeutic Efficacy and Safety of UMSCs for the Management of Retinitis Pigmentosa (RP)

Retinitis pigmentosa (RP) is the most common hereditary retinal disorder (accounts for 20% of children attending blind schools in Pakistan) which causes degeneration of rod and cone photoreceptors. Rods and cones largely depend on the retinal pigment epithelium for their proper functioning. Various growth factors and their receptors are present in retinal epithelium and a number of genes are responsible for the production of these growth factors. Genetic mutation in any of these genes causes retinal degeneration by progressive loss of retinal pigment epithelium and photoreceptors. The disease initially starts with night blindness and leads to the loss of central vision and eventually total blindness. To date, there is no definitive cure for patients suffering from RP. Recently, stem cell based therapies have shown great promise for the management of RP. It is well documented that umbilical cord derived mesenchymal stem cells (UMSCs) have the ability to release various paracrine and immunomodulatory factors that are similar to those synthesized by retinal pigment epithelium. Multiple routes including systemic (intravenous) and localized (subretinal, intravitreal, suprachoroidal and sub-tenon) have been employed to administer UMSCs for the management of RP. It is important to note that deep sub-tenon region (space between the sclera and the conjunctiva) acts as both natural culture medium for cells and as immune privileged site because of avascularity of the region. It has been reported that the injection of UMSCs in sub-tenon space of human subjects have improved the visual acuity even after 1 year post-injection. In addition, the injection of UMSCs in suprachoroidal space enhances the entry of growth factors released by the cells into choroidal flow and maintain the constant growth factors secretion to the choroidal and retinal tissues. Limoli and colleagues were the first to report the suprachoroidal administration of cells being the safe mode of cell delivery with no complications. The present study is aimed to investigate the safety and therapeutic efficacy of UMSC injection employing two different routes (sub-tenon injection versus suprachoroidal injection) for the treatment of RP in human subjects.