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Objective
To study the therapeutic effect and mechanism of autologous platelet-rich plasma (PRP) on rabbit traumatic optic neuropathies (TON) and retina.
Methods
Forty adult New Zealand white rabbits were selected to establish the optic nerve clamp injury model in their right eyes.According to the random number table method, 36 New Zealand white rabbits with effective model were randomly divided into model control group, normal saline control group and PRP group, 12 for each group.Another 12 healthy rabbits served as the normal control group.Rabbit autologous blood was collected to prepare PRP.The retrobulbar 20 μl PRP/20 μl saline solution injection was administered every two days near the injury after modeling according to grouping.The injection was carried out for 10 times.There was no other interference administrated to the model control group except the normal anti-infective treatment.No interference was given to the normal control group.At 30 and 60 days after modeling, the eyeballs and optic nerves of right eyes were harvested through sacrificing the animals by anesthetic overdose, three eyes for each time.Histopathological assessments were performed to observe the morphological changes of retina and optic nerve, and to evaluate the changes of retinal ganglion cells (RGCs) density and retinal nerve fiber layer (RNFL) thickness.Immunohistochemistry was used to assess the expressions of apoptosis factors caspase-3 and B cell lymphoma-2(Bcl-2). Quantitative real-time PCR and Western blot were used to detect the mRNA and protein expressions of brain-derived neurotrophic factor (BDNF) and growth associated protein-43 (Gap-43). This study protocol was approved by the Experimental Animal Ethics Committee of Wuhan University (No.E2019072805). The use and care of animals complied with ARVO statement.
Results
The thickness of RNFL and number of RGCs at 30 days and 60 days after modeling were (6.60±1.16) μm, (6.89±1.21) μm, (13.00±1.00)/field of vision, (20.00±2.65)/field of vision in the PRP group, respectively, and were (4.80±0.43)μm, (2.18±0.23)μm, (6.33±0.58)/field of vision, (10.33±1.53)/field of vision in the model control group, respectively.The number of RGCs in the PRP group at 60 days was higher than that at 30 days after modeling, the number of RGCs in the PRP group was higher than that in the model control group, the thickness of RNFL in the PRP group was higher than that in the model control group; and the differences were statistically significant (all at P<0.05). At 30 and 60 days after modeling, the positive expression A value of caspase-3 protein in the normal saline group and model control group were higher than those in the normal control group and PRP group, while the positive expression A value of Bcl-2 protein in the PRP group was higher than those in the model control group and normal saline group, and the differences were statistically significant (all at P<0.05). The mRNA level and protein content of BDNF and Gap-43 in the retina and optic nerves at 30 days and 60 days after modeling in the PRP group were higher than those in the model control group, and the differences were statistically significant (all at P<0.05), but the mRNA and protein expression levels of BDNF and Gap-43 in different tissues in the PRP group at 60 days after modeling were lower than those at 30 days after modeling (P<0.05).
Conclusions
PRP can effectively inhibit the apoptosis of RGCs and the secondary injury of the retina after optic nerve injury, promote cell anti-apoptosis effect of RGCs, thereby retard the damage of the retina and optic nerve after TON, and also promote the repair of optic nerve and retina through upregulating the expression of nerve growth factors.