Abstract
Purpose :
We have recently developed a biodegradable scaffold composed of human fibrin for use in RPE transplantation. In this study we developed a surgical procedure for placement of fibrin scaffolds in the subretinal space and tested the degradation kinetics and safety profile of fibrin scaffolds using an in vivo porcine subretinal implantation model.
Methods :
Fibrin scaffolds were cast by mixing human fibrinogen (40mg/mL) and thrombin (50U/mL) solutions in a custom mold. Once polymerized, scaffolds of 1.5mm x 5.0mm x 0.2mm were obtained using a punch and stained with trypan blue for visualization. Scaffolds were placed in the subretinal space of one eye of a domestic pig (n >8) following partial vitrectomy and creation of a retinal bleb, using a novel inserter tool. Scaffold degradation was assessed postoperatively by fundus exam, OCT, and postmortem histology for up to 12 weeks.
Results :
Immediately following implantation, the scaffold was visible under the retina. After 3 days, the retina appeared flat except at the implantation site, in which the elevation coincided with the thickness of the scaffold. Histology at this early time point confirmed the gel was placed successfully within the subretinal space without damage to the surrounding tissue. At 1 and 2 weeks, OCT images demonstrate scaffold degradation. By the 8th week, the scaffold appeared to have degraded in fundus exams and by OCT (n=4). Histologically, at the implantation site, the retina was reattached and morphologically we could not detect damage to the underlying RPE or the overlying neurosensory retina.
Conclusions :
Fibrin scaffolds implanted in the subretinal space degrade within 8 weeks without any detectable adverse effects. Fibrin gels offer a bio-degradable scaffold for use in RPE transplantation, potentially improving upon current non-degradable scaffolds.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.