In-vitro and ex-situ regional mass spectral analysis of phospholipids and glucose in the vitreous humor from diabetic and non-diabetic human donors

The Vitreous Ecosystem in Diabetic Retinopathy: Insight into the Patho-Mechanisms of Disease

“…Even mid-vitreous sampling notations rarely have anterior or posterior specific distance descriptions in relation to the lens or pre-macular area. The specific location is important, illustrated by varying glucose and VEGF concentrations in the vitreous, with higher concentrations found in the pre-macular vitreous compared to the mid-vitreous [23,44]. Bainbridge and colleagues have shown that oxygen tensions closer to the posterior pole are higher compared to the mid-vitreous or periphery in PDR [45].…”

“…Intravascular exposure to high glucose, glycated and glycosylated products, and environmental stress such as hypertension can lead to pericyte loss and oxidative stress in diabetic retinopathy [48]. Glucose levels in the posterior region of the vitreous humor have been shown to be higher than the central or anterior regions of the vitreous humor in diabetics [44], and may be reflective of the metabolic process at the retina level. However, even prior to the vascular findings of microaneurysms and other microvascular changes found in clinical DR, pre-clinical neurodegenerative findings can be found in DR and are thought to be induced through innate immunogenic and pro-inflammatory responses [49].…”

Hyaluronic acid–lipid binding

“…Therefore, with diabetes, only an increase in PL concentration in the VH could potentially increase HA–PL. Relatively higher levels of PLs and glucose in the VH of diabetic patients compared to VH from non-diabetics has been observed [ 25 ] and is believed to be caused by a decrease in the blood–retinal barrier with diabetes [ 50 ]. Quantitative studies to determine PL concentrations in the VH of diabetics are needed to determine if PL contributes to increased VH liquefaction in diabetic patients.…”

“…PLs have been found in human [ 25 ] and porcine VH [ 26 ]. The lipids in the anterior region of the VH come from the lens and the lipids in the posterior region of the VH come from the retina.…”

“…The lipids in the anterior region of the VH come from the lens and the lipids in the posterior region of the VH come from the retina. Elevated levels of lipid are observed in the VH of humans with diabetes [ 26 ] and it is speculated that these lipids contribute to vitreous liquefaction [ 25 , 26 ]. Liquefaction is the result of the collapse or contraction of the collagen/hyaluronan network, where collagen can be considered to act as the scaffold and HA fills the spaces in between [ 1 , 27 ].…”