Abstract
Purpose :
This study aims to assess the potential benefit of a unique and highly-defined population of human bone marrow-derived SSCs (sorted on surface marker CD362+) in a murine model of diabetic retinopathy (DR).
Methods :
C57/Bl6 male mice (12 weeks old) were injected with streptozotocin (in citrate buffer, 5x single IP injections/day,50 mg/kg) to induce diabetes(DB) while other animals received citrate buffer alone (non-diabetic controls,NDB). Groups were kept for 6 months, blood glucose and body weight monitored monthly. At 6 months post-induction DB mice received a single dose of 100µl of 1x106 CD362+SSCs(n=7) or CD362-SSCs(n=6) in DMEM, delivered via intravenous (tail-vein) injection. Control groups of DB(n=5) and NDB(n=8) mice received PBS injections. Four weeks post-treatment, in vivo retinal function (scotopic electroretinogram,ERG; stimuli range 0.008-25cd.s.m-2) and thickness (OCT) were measured. Eyes were enucleated and processed for immunofluorescence staining on retinal flat-mounts and cryosections (isolectin B4/collagen IV; Brn3a/Iba-1), and imaged using confocal microscopy. Acellular capillaries, retinal ganglion(RGC) and microglial cell(MC) counts were performed. qPCR analysis of retinal tissue show no human DNA detected 3 days after treatment.T-test and ANOVA were used for statistical analyses.
Results :
Retinal function in DB mice revealed a significant reduction in photoreceptor (a-wave,P<0.01) and ON-bipolar cell responses (b-wave,P=0.01) compared with NDB group. Mice treated with CD362-SSCs showed an improved ON-bipolar cell response similar to NDB controls (P>0.05). The retina was significantly thinner in DB mice treated with PBS and CD362-SSC than NDB mice (P<0.0001), however CD362+SSC treatment maintained retinal thickness (P>0.05). There were reduced Brn3a-positive RGCs in DB mice (P=0.04 vs NDB), while SSC-treated DB groups showed significant retinal neuroprotection. Analyses of Iba-1 positive MCs showed that CD362+ treated mice had less MCs in the retina. Increased acellular capillary formation (hallmark of DR progression) occurred in DB mice (P<0.05 vs NDB). SSC treatment prevented capillary loss, with CD362+SSC (P<0.01) being more effective than CD362-SSC (P<0.05).
Conclusions :
A single systemic dose of human bone marrow-derived CD362+SSC show significant therapeutic benefit by protecting against progression of key neurovascular pathology observed in DR.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.