Study Of Corneal And Choroidal Neovascularization On Streptozotocin-Induced Diabetic Mice

Background and AimAngiogenesis was broadly participating in normal physiological of development and abnormal pathological processes such as inflammation, wound and healing, tumor growth and metastasis. Recently, more attention was paid on the progress of pathological angiogenesis. Diabetes mellitus (DM) was a kind of metabolic disease characterized by abnormal glucose metabolism. With the soaring of living standard, DM prevalence rate showed a rising trend. DM can cause a number of complications which not only seriously affected the life quality of patients, but also increased the medical burden of human society. DM can cause excessive proliferation of blood vessels in retina of eyes, and it can inhibit collateral circulation in extremity ischemia and ischemic cardiovascular disease. How about the relationship between DM and neovascular? And whether DM has the same effect between macrovascular and microvascular system? What is the mechanism of the seemingly contradictory results? Understand these questions will not only help to prevent various complications of DM, but also help to effectively control the development of new blood vessels, and to provide a new path to prevent neovascular diseases and promote wound healing.STZ (streptozotocin) induced DM model, and alkali-burn induced corneal neovascularization (CNV) as well as laser-induced choroidal neovascularization (ChNV) model were used to explore the effect of hyperglycemia on the process of corneal and choroidal neovascularization. Since possible differences of micro-environment and mechanism of neovascularization between cornea and choroidal, we compare the similarities and differences between CNV and ChNV. Additionally, our study reveal the effect of high glucose state on wet age-related macular degeneration (AMD).Materials and methods Preparation of DM model 50 BABL/c mice and 12 C57BL/6 mice were randomly divided into experimental group (DM group) and control group (Con group). To induce DM, mice were continuously intraperitoneal injected of 1%STZ (Streptozotocin, MLDS) in citrate buffer, (50mg/kg) for 5 days. The same amount of citrate solution continuously intraperitoneal injection was saved as control.Preparation of CNV model 26 BALB/c mice were intraperitoneal injected of STZ to induce DM, the other 24 mice were injected of buffer as control group. 14 days after alkali injury, corneal neovascularization were photographed and analyzed for both groups, then corneas were enucleated for frozen section. Slides were stained with anti-CD31 mAb to test the corneal neovascularization. Corneas at 2, 4 and 7 days after alkali injury were collected for mRNA extraction followed by reverse transcription-polymerase chain reaction (RT-PCR) to detect and compare the angiogenic factors expression.Preparation of ChNV model 12 C57BL/6 mice (6 for DM and 6 for control) and laser induced choroidal neovascularization were used. 14 days after retinal laser photocoagulation, fundus fluorescein angiography and choroidal stretched staining were conducted to compare the ChNV formation between two groups, and the effect of high level glucose state on ChNV formation procession was analyzed.ResultsThe random blood glucose level was above the standard (≥11.1mmol/L) after intraperitoneal injection in the DM group. Compared to Con mice, weight lose with increased water drinking and urine output was significant in DM mice. Repeated experiments with similar results indicate no significant difference was found of the CNV area between DM mice and Con mice (P> 0.05).The laser induced ChNV area in DM mice was impaired than those of Con mice control, statistically significant difference (P <0.05).ConclusionThe MLDS-induced DM model of BALB/c or C57BL/6 mice has the characteristic of low mortality rate and high blood glucose level and long duration. It provided an ideal animal model for DM-related diseases research.It had no obvious effect on the occurrence and development of CNV for the early hyperglycemia by MLDS induces.In C57BL/6 DM mice induced by MLDS, high glucose level inhibit the development of laser induced ChNV, suggesting that hyperglycemia had anti-angiogenesis effect on the process of wound healing. Our result will help us to further understand the relationship between DM and wet AMD.