Abstract
Purpose:
Previously we have shown that adipose stromal cells (ASC) therapeutically rescue against vascular inflammation and apoptosis in diabetic retinopathy. In this study, we tested if adipose stromal cell conditioned media (ASC-CM) can protect retinal damage in-vivo and may serve as an alternate cell free therapeutic modality for retinal diseases.
Methods:
Human ASC were cultured to confluence in serum free conditioned media for 72h and cell free supernatant was collected. Basal essential media (BEM) prepared in similar fashion without cells served as control. Two animal models namely, Ischemia-reperfusion (I/R) injury Lewis rat and athymic nude rat having streptozotocin-induced diabetes of 2-mos duration were tested. Intravitreal injection was performed with ASC-CM into the right eye (2μL) and an equal volume of BEM into the left eye. About 7 days post injection, retinal function assessed by Electroretinogram (ERG), retinal histological changes were observed by light microscopy and vascular leakage by FITC-albumin extravasation method.
Results:
I/R resulted in a significant reduction in peak “b” wave amplitude (as measured by ERG) compared to un-injured control rats, and this reduction was significantly improved by ASC-CM at day-7 post injection (51±11 v/s 90±13 μvolts, p<0.02; n=6). Subsequently, retinal histological analyses at day-7 revealed an increase in retinal thickness (207±9 v/s 245±6.0μm, p<0.03; n=5); decrease in gliosis as measured by expression of glial fibrillary acidic protein (28±4 v/s 11±2 RFU/sq.mm, p<0.001, n=5) and decrease in apoptosis (78±6 v/s 46±12 RFU/sq.mm, p<0.01, n=5) as measured by Caspase-3 staining in retina from injured eyes received ASC-CM compared to injured eyes received BME. In addition, in a chronic diabetic model, increased vascular leakage in diabetic animals that received BME were significantly reduced in diabetic animals that received ASC-CM (6.0±1.0 v/s 3.1±0.3 RFU/100µm, n=5; p<0.02) within 7 days.
Conclusions:
Taken together with both acute and chronic retinopathy models, our findings suggest that ASC-CM may serve as a cell free therapy against retinal pathology with its ability to down modulate gliosis, vascular permeability and neural cell death. Ongoing and future studies will assess the possible beneficial proteins from ASC-CM that are implicated in the observed paracrine effects of ASC in the retina.
Keywords: 721 stem cells •
499 diabetic retinopathy •
557 inflammation