Objective To investigate the retinal toxicity and verify the safe dose of intravitreal injection of nonsteroid anti-inflamatory drug,diclofenac sodium.Methods Twenty-eight healthy adult white rabbits were divided at random into 7 groups and received in every right eye the intravitreal injection of a single dose of diclofenac sodium solution ranging from 0.4-0.1 mg/0.1ml respectively ,the left eyes were regarded as conreol ones.Before injection and on the 1st,3rd,7th,14th,21st,and 28th day after injection the electroretinography on both eyes was examined.On the 28th day after injection the retinas of two rabbits of every group were examined by using light microscopy.On the 10th and 30th day after injection the retinal tissues around the optic nerve sisk of two eyes from every group at random were tested by using transmission electron microscopy.Results The retio of amplitude ofb wave of electroretinography in 0.4mg and 0.5mg groups had no sighnificant difference from groups before injection,the retinal tissues showed no structural changes in light and ecectron microscopy examination.The ratio of amplitude ofb wave of photoptic electroretinogrphy in 0.6mg groups in the early stage after injection was markedly reduced（P＜0.05）and returned to that before injection with time,reversible change of the edematou retina was discovered.The ratio of amplitude of b wave of electroretinography in 0.7-1.0mg groups was distinctly descreaded after injection（P＜0.05 or P＜0.01）,the cells of all the retinal layer revealed apparent and irreversible damage.Conclusion The largest dose of safety of intravitreal diclofenac sodium should be not more than 0.6mg.The toxic effect of intravitreal diclofenac sodium on retina is concerned mostly to cones and rods.
Objective To develop a diclofenac sodium-loaded gelatin scaffold with anti-inflammatory activity and provide a new avenue for alleviating the inflammatory response and enhancing cartilage regeneration in vivo. Methods Diclofenac sodium was homogeneously mixed with gelatin to prepare a diclofenac sodium-loaded porous gelatin scaffold by freeze-drying method as the experimental group, and a pristine porous gelatin scaffold was served as a control group. The general morphology of the scaffold was observed, the pore size of the scaffold was measured by scanning electron microscopy, the porosity of the scaffold was calculated by drainage method, the loading of diclofenac sodium into the gelatin scaffold was detected by fourier transform infrared spectrometer and X-ray diffraction examinations, and the release kinetics of diclofenac sodium from gelatin scaffold was tested using an in vitro release assay. The two scaffolds were co-cultured with lipopolysaccharide-predisposed RAW264.7 in vitro, and the expressions of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) were detected by reverse transcription polymerase chain reaction (RT-PCR), enzyme-linked immuno sorbent assay, and Western blot, to detect the in vitro anti-inflammatory effect of the drug-loaded scaffold. Thereafter, the second generation chondrocytes of New Zealand white rabbits were inoculated on the two groups of scaffolds for in vitro culture, and the cytocompatibility of the scaffold was tested by live/dead staining and cell counting kit 8 assay, the feasibility of in vitro cartilage regeneration of the scaffold was evaluated via gross observation, HE staining, Safranin-O staining, and immunohistochemical collagen type Ⅱ staining, as well as biochemical quantitative analyses. Finally, the two groups of chondrocyte-scaffolds were implanted subcutaneously into New Zealand white rabbits, and after 4 weeks, the general observation, HE staining, safranin O staining, immunohistochemical collagen type Ⅱ staining, and biochemical quantitative analyses were performed to verify the cartilage regeneration in vivo, and the expression of inflammation-related genes CD3 and CD68 was detected by RT-PCR to comprehensively evaluate the anti-inflammatory performance of the scaffolds in vivo. Results The two scaffolds exhibited similar gross, microporous structure, pore size, and porosity, showing no significant difference (P>0.05). Diclofenac sodium was successfully loaded into gelatin scaffold. Data from in vitro anti-inflammatory assay suggested that diclofenac sodium-loaded gelatin scaffold showed alleviated gene and protein expressions of IL-1β and TNF-α when compared with gelatin scaffold (P<0.05). The evaluation of cartilage regeneration in vitro showed that the number of living cells increased significantly with the extension of culture time, and there was no significant difference between the two groups at each time point (P>0.05). White cartilage-like tissue was regenerated from the scaffolds in both groups, histological observation showed typical cartilage lacuna structure and specific cartilage extracellular matrix secretion. There was no significant difference in the content of cartilage-specific glycosaminoglycan (GAG) and collagen type Ⅱ between the two groups (P>0.05). In vivo experiments showed that the samples in the experimental group had porcelain white cartilage like morphology, histologic staining showed obvious cartilage lacuna structure and cartilage specific extracellular matrix, the contents of GAG and collagen type Ⅱ were significantly higher than those in the control group, and the protein and mRNA expressions of CD3 and CD68 were significantly lower than those in the control group, with significant differences (P<0.05). ConclusionThe diclofenac sodium-loaded gelatin scaffold presents suitable pore size, porosity, and cytocompatibility, as well as exhibited satisfactory anti-inflammatory ability, providing a reliable scheme for alleviating the inflammatory reaction of regenerated cartilage tissue after in vivo implantation and promoting cartilage regeneration in vivo.