Background:
Diabetic retinopathy (DR) is one of the most common side effects of diabetes. We aimed to investigate the effects of crocin and crocetin (as a deglycosylated form of crocin in blood stream) in gene expression or protein levels of vascular endothelial growth factor (VEGF), vascular endothelial growth factor-receptor1 (VEGFR-1), matrix metalloproteinases2 (MMP-2), matrix metalloproteinases9 (MMP-9) and thrombospondin-2 (TSP-2) in high glucose cell culture media.
Methods:
The retinal pigment epithelium (RPE) cells were exposed to high glucose (HG, 30 mM glucose concentration) and normal glucose (NG, 24.5 mM mannitol + 5.5 mM glucose) for six days. RPE cells were treated in four treatment groups (crocin, crocetin, Bevacizumab, and crocin + Bevacizumab). Gene expressions were measured using quantitative real-time PCR, and proteins level was evaluated by western blot.
Results:
Findings showed that VEGF gene expression and protein level significantly decreased in all treatment groups. In addition, reduction in VEGFR1 gene expression was significantly higher in Bevacizumab and crocin + Bevacizumab groups than other groups. Only, crocin and crocetin could reduce the gene levels of MMP-2 and MMP-9. In addition, TSP-2 protein levels increased when HG cells were exposed crocin or crocin + Bevacizumab groups.
Conclusion:
Our data showed that crocin and crocetin have anti-VEGF function similar to Bevacizumab, act as an anti-angiogenic agent. Also, crocin and crocetin could decrease MMP-2 and MMP-9 gene levels, as inflammatory and angiogenesis factors. As a result, crocin and crocetin have protective effects against angiogenesis and inflammation in DR.
Amniotic fluid (AF) is a clear yellow fluid that surrounds the fetus during pregnancy. The amniotic sac consists of 2 layers: the amnion and the chorion. Osmotic and hydrostatic forces cause the maternal plasma to pass through the fetal skin and generate the AF. AF allows the fetus to grow inside the uterus, supports it from injuries, retains consistent pressure and temperature, and enables the exchange of body chemicals with the mother. At first, it consists of water and electrolytes but after the 12-14th wk the liquid also contains carbohydrates, proteins, lipids, phospholipids, urea, hormones, and some biochemical products. AF appearance is characterized by the grade of cloudiness and the number of flakes of the vernix. The volume of AF increases with the fetus’s growth. Its appearance depends on the gestational age. In addition to differentiated cells, stem cells are also found within the AF. These cells express embryonic-specific cell markers and bear high self-renewal capacity and telomerase activity. AF stem cells possess the potential to differentiate into osteogenic, cardiac, skeletal muscle, lung, neuronal, kidney, bone, cartilage, ovarian and hepatic cells in vitro. They represent a great promise in regenerative medicine for the reconstruction of bio-artificial tissues and organs in vivo. The purpose of this paper was to briefly review the development and function of AF and the application of its stem cells in cell therapy.
Key words: Amniotic fluid, Stem cells, Differentiation, Regeneration, Tissue engineering.
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