Search

Retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration are the main clinical blinding eye diseases with complex etiology and irreversible damage to vision. CX3CR1 is a specific receptor of the chemokine CX3CL1. Both of them participate in various physiological functions and pathological changes of the whole body through regulating the immune system of the body. In recent years, studies have pointed out that CX3CR1 regulates the activity and function of retinal microglia, which play an important role in the process of retinal degenerative diseases. In this paper, the structure and function of the chemokine receptor CX3CR1 and the role of microglia in retinal degenerative diseases were reviewed, so as to provide ideas and directions for future research and treatment of such diseases.

AIM: To explore the temporal mitochondrial characteristics of retinal pigment epithelium (RPE) cells obtained from human embryonic stem cells (hESC)-derived retinal organoids (hEROs-RPE), to verify the optimal period for using hEROs-RPE as donor cells from the aspect of mitochondria and to optimize RPE cell-based therapeutic strategies for age-related macular degeneration (AMD). METHODS: RPE cells were obtained from hEROs and from spontaneous differentiation (SD-RPE). The mitochondrial characteristics were analyzed every 20d from day 60 to 160. Mitochondrial quantity was measured by MitoTracker Green staining. Transmission electron microscopy (TEM) was adopted to assess the morphological features of the mitochondria, including their distribution, length, and cristae. Mitochondrial membrane potentials (MMPs) were determined by JC-1 staining and evaluated by flow cytometry, reactive oxygen species (ROS) levels were evaluated by flow cytometry, and adenosine triphosphate (ATP) levels were measured by a luminometer. Differences between two groups were analyzed by the independent-samples t-test, and comparisons among multiple groups were made using one-way ANOVA or Kruskal-Wallis H test when equal variance was not assumed. RESULTS: hEROs-RPE and SD-RPE cells from day 60 to 160 were successfully differentiated from hESCs and expressed RPE markers (Pax6, MITF, Bestrophin-1, RPE65, Cralbp). RPE features, including a cobblestone-like morphology with tight junctions (ZO-1), pigments and microvilli, were also observed in both hEROs-RPE and SD-RPE cells. The mitochondrial quantities of hEROs-RPE and SD-RPE cells both peaked at day 80. However, the cristae of hEROs-RPE mitochondria were less mature and abundant than those of SD-RPE mitochondria at day 80, with hEROs-RPE mitochondria becoming mature at day 100. Both hEROs-RPE and SD-RPE cells showed low ROS levels from day 100 to 140 and maintained a normal MMP during this period. However, hEROs-RPE mitochondria maintained a longer time to produce high levels of ATP (from day 120 to 140) than SD-RPE cells (only day 120). CONCLUSION: hEROs-RPE mitochondria develop more slowly and maintain a longer time to supply high-level energy than SD-RPE mitochondria. From the mitochondrial perspective, hEROs-RPE cells from day 100 to 140 are an optimal cell source for treating AMD.

Retinal degenerative disease is a major disease that affects human vision. It damages human photoreceptor cells and damages human vision. And the mammalian retina does not have the ability to regenerate, once the disease will seriously affect people's normal life. At present, there is no clear way to prevent and alleviate these diseases, but the transplantation of photoreceptors to supplement the damaged photoreceptors in the retina can treat retinal diseases. In this paper, we will discuss the current situation and techniques of photoreceptor transplantation to restore vision in retinal degenerative diseases.

Retinal degenerative diseases are kinds of leading cause of blindness characterized by photoreceptor apoptosis and progressive neuronal degeneration. A large body of research has shown the evidence of inflammation reaction in such diseases. Retinal neuroinflammation may be a main factor resulting in apoptosis of photoreceptors and neurodegeneration of retina. In addition, the inflammatory response is not only detected in the retina, but also in aqueous humor, vitreous and even in blood, which forms a persistently very low degree, and chronic inflammatory environment. In this review, we focus on the development of microinflammatory response and its predictor for disease outcomes.

Retinal degeneration is the primary cause of visual impairment and blindness. However, in advanced stage of the disease, the majority or all photoreceptors are lost, effective therapeutics has not been established. In recent years, a large number of studies have provided new ways for the replacement of photoreceptors and three-dimensional retinal culture has emerged to produce retinal photoreceptors and tissues of both fetal mouse and human, providing the cell source of photoreceptors replacement therapy for treating retinal degenerative diseases. This review focuses on the development of three-dimensional retinal culture techniques and photoreceptors transplantation experiments, and the existing application strategies and limitations of retinal organoids in the replacement therapy of retinal degeneration, which provide a theoretical reference for the optimization of 3D retina in photoreceptors replacement therapy.

AIM: To explore whether ectopic expression of human melanopsin can effectively and safely restore visual function in rd1 mice. METHODS: Hematoxylin-eosin staining of retinal sections from rd1 mice was used to detect the thickness of the outer nuclear layer to determine the timing of surgery. We constructed a human melanopsin-AAV2/8 viral vector and injected it into the subretinal space of rd1 mice. The Phoenix Micron IV system was used to exclude the aborted injections, and immunohistochemistry was used to validate the ectopic expression of human melanopsin. Furthermore, visual electrophysiology and behavioral tests were used to detect visual function 30 and 45d after the injection. The structure of the retina was compared between the human melanopsin-injected group and phosphate buffer saline (PBS)-injected group. RESULTS: Retinas of rd1 mice lost almost all of their photoreceptors on postnatal day 28 (P28). We therefore injected the human melanopsin-adeno-associated virus (AAV) 2/8 viral vector into P30 rd1 mice. After excluding aborted injections, we used immunohistochemistry of the whole mount retina to confirm the ectopic expression of human melanopsin by co-expression of human melanopsin and YFP that was carried by a viral vector. At 30d post-injection, visual electrophysiology and the behavioral test significantly improved. However, restoration of vision disappeared 45d after human melanopsin injection. Notably, human melanopsin-injected mice did not show any structural differences in their retinas compared with PBS-injected mice. CONCLUSION: Ectopic expression of human melanopsin effectively and safely restores visual function in rd1 mice.

Very small embryonic-like stem cells(VSELs)is a rare population of pluripotent adult stem cells, whose biological nature is similar to that of embryonic stem cells, firstly identified in murine bone marrow(BM)and human cord blood(CB)by Kucia and his group in University of Louisville. They have similar outlook to embryonic stem cells such as cell morphology and markers and similar inner pluripotent characteristics which make them be the most potential seed cells in the cell replacement therapy. In this review, we will focus on research advance about VSELs and clinical significance in the stem cell transplantation treatment of retinal degenerative diseases.