Delivery of Multifunctional Collagen Constructs for Retinal Stem Cell Transplantation via Lens Sparing Pars Plana Vitrectomy

Abstract

Purpose: : Transplantation strategies to deliver stem cells in experimental therapies for retinal degenerative diseases do not yet demonstrate adequate distribution of cells across the neural retina. This may be due to anatomical and physiological features of the host retina that prevent optimal migration and integration of the injected cells. This study involved pre-clinical studies in large animals using multifunctional collagen constructs to facilitate the transplantation and integration of human Müller stem cell derived retinal ganglion cell (RGC) precursors into the inner retina

Methods: : Cellular scaffolds were developed using plastic compression of type 1 collagen with triamcinolone particles embedded into the collagen structure. Human Müller stem cells were cultured using a protocol developed to differentiate these cells towards a RGC fate. Differentiated cells were then attached to the collagen matrices for transplantation. Pars plana vitrectomy with or without lensectomy was performed in ten rabbits followed by fluid/air exchange. Cellular scaffolds were delivered via a 20G vitreoretinal cannula in the presence of Chondroitinase ABC onto the medullary raphe (posterior pole) and flattened out on the surface of the inner retina by manipulation and air tamponade. Migration and localisation of transplanted cells was examined by immunohistochemistry at 4 weeks following transplantation. Monitoring of scaffold architecture was performed using SD-OCT technology.

Results: : Successful delivery of multifunctional collagen constructs was achieved using the pars plana surgical approach. Collagen constructs remained apposed to the host retina using air tamponade alone. Cells were observed to have migrated from the collagen scaffold towards the host inner retina at four weeks following transplantation. No evidence of tractional retinal detachment was observed as a consequence of construct delivery although entry site retinal breaks were observed in three animals.

Conclusions: : Multifunctional collagen constructs delivered directly onto the inner retinal surface via lens sparing pars plana vitrectomy may constitute a viable strategy to facilitate widespread and uniform distribution of transplanted cells within the inner retina. This surgical technique may be readily translated to the human eye and offers hope for future retinal stem cell transplantation strategies for treatment of inner retinal degeneration.

Keywords: transplantation • retina: proximal (bipolar, amacrine, and ganglion cells) • vitreoretinal surgery