Abstract
Purpose:
Diabetic retinopathy is a common blinding disease characterized by the progressive degeneration of retinal vessels, which in the long term causes vision loss. It has been shown that endothelial progenitor cells (EPCs) are a promising source for therapeutic revascularization by regenerating damaged blood vessels in the retinal vasculature. EPCs can be differentiated from different sources of human pluripotent stem cells (hPSC) such as human embryonic stem cells (hESCs) or human induced pluripotent stem cells (hiPSCs). In order to better characterize and optimize the regenerative potential of these cells we need to isolate them as a pure and large population. Therefore, this study compared different methods to enrich EPCs and to enhance their production from hiPSCs. CD34 is the most commonly used marker for these cells and is therefore also used in this study.
Methods:
hiPSCs were grown to confluency on Matrigel coated plates in mTeSR-1 medium. Then, they were exposed to different conditions, growth factors and bioactive small molecules. The medium was changed according to the experimental plan and cells were fixed on different days from day 5 to 8 and finally immunohistochemistry for CD34 was used to identify the cells of interest.
Results:
We found that administration of BMP4, Activin A and BIO (Wnt signalling activator) at an early phase and then VEGF-165 and SB431542 (TGFβ-receptor type one inhibitor) during the later phase of treatment led to efficient differentiation of CD34+ cells from hiPSCs within five days. Therefore, this study presents an efficient approach to generate hiPSC-derived EPCs by modulating four signalling pathways. This can be useful in developing novel therapeutic avenues for cellular regeneration in diabetic retinopathy.
Conclusions:
We developed defined culture conditions to enrich CD34+ EPCs which will enable us to isolate these cells in sufficient quantities and characterize them in more detail.