Effects Of Macrophages On Survival And Axonal Regeneration Of Rat Retinal Ganglion Cells In A Coculture Model

BackgroundThe optic nerve and the retina of mammals are parts of the central nervous system (CNS). The optic nerve, composed of axons of retinal ganglion cells (RGCs), can not regenerate after optic nerve injury. RGCs are also the main damage cells in diseases, such as glaucoma and ischemic retinal diseases. These diseases result in serious impairment of vision. In recent studies, there is no agreement among many views in terms of optic nerve regeneration. In the peripheral nervous system (PNS), macrophages remove debris and stimulate neurons into an active state. However, the CNS cannot undergo this progress. The peripheral nervous system (PNS) is mediated by Schwann cells, which are (different from oligodendroglia in the CNS, and can release numerous pro-inflammatory cytokines, chemokines, growth factors, and other signals which can promote axon regeneration.In recent studies, lens injury can cause macrophages to enter the eye and stimulate retinal ganglion cells to regenerate axons beyond the injury site. It hints that macrophages play a significance role in the process of optic nerve regeneration.Therefore we set up a co-culture system of macrophages and RGCs withTranswell chambers. The axonal growth and survival time of RGCs in the model were observed under a phase contrast microscope. purposeTo determine the effects of macrophages on the survival and axonal regeneration of retinal ganglion cells in vitro.MethordsA coculture model of rat macrophages collected from the peritoneal cavity with rat RGCs was established using transwell chambers. RGCs cultured without macrophages were served as controls. The axonal growth and survival time of RGCs in the model were observed under a phase contrast microscope. The survival of RGCs was determined by counting the cells with Trypan blue staining. The average lengths of the processes of RGCs cultured on days 1, 3 and 5 were measured and calculated.RusultsThe average counts of viable cells with Trypan blue staining in the coculture system were (35.50±2.92), (28.20±3.36), (18.70±3.95), (8.80±1.55) on days 1, 3, 5 and 7, respectively. And there were no statistically significant differences when compared to controls [(36.20±2.35), (27.10±2.96), (15.80±3.04), (8.40±2.01), respectively; P>0.01]. The average length of RGCs'processes in the coculture system were (19.79±3.98)μm, (68.30±4.07)μm, and (95.51±6.51)μm on days 1, 3 and 5, respectively. The processes of RGCs cocultured with macrophages were significantly longer when compared to controls [(15.28±1.28)μm, (58.18±4.22)μm, and (82.61±3.75)μm, respectively; P <0.01]. ConclusionOur results showed that macrophages could promote significantly the axonal regeneration of RGCs in a coculture system, but no obvious effect on the cell survival.