Catalina Corbu

CD146- and CD105-positive phenotypes of retinal ganglion cells. Are these in situ proofs of neuronal regeneration?

The in vivo identity of stem cells is not yet clear. Numerous studies involve the perivascular niches as providers of stem cells during regenerative processes. CD146, in humans, as well as gicerin, at chicken, play roles in neuronal development and neurites extension. CD146 is a marker of stemness but also a pericytary marker. Stem cells in vascular niches can differentiate in neural cells. By applying CD146 and CD105 antibodies on human retinas from glaucomatous eyes, CD146-positive retinal ganglion cells (RGCs) were found, some being placed in perivascular positions; ongoing processes of neurites extension were related to these neurons. On other hand, RGCs were positively labeled by CD105 antibodies. These results support the hypothesis that in glaucoma eyes the CD146-positive RGCs result from regenerative processes driven by stem cells in the retinal perivascular niches. Further experiments are needed to evaluate whether CR146-positive neurons indicate also a physiological process of maintenance of retina.

Stem potentialities of the human iris - An in situ immunohistochemical study.

According to recent findings multiple human tissues harbor stem cells which, in turn, have different levels of stemness. We performed an immunohistochemical study on paraffin-embedded samples to test if the in situ stromal cells of the iris of the human eye (EI) have immune stem/progenitor phenotypes. Eviscerated post-traumatic eyes from eight patients were studied. These irises were found to contain fibroblastoid stromal cells with a CD34+/CD45+/CD105+/CD117+/DOG1+/PDGFR-α+/vimentin+/nestin-/collagen III- phenotype. These were assumed to be possible stem/progenitor cells involved in physiological processes of iridial stromal maintenance. All the vascular endothelia were CD34+/CD105+/vimentin+. Newly formed nestin+ endothelia were also found; this finding was supported by evidence of filopodia-projecting CD34+ endothelial tip cells, which demonstrated active processes of sprouting angiogenesis. The phenotype of the stromal cells also suggests a role of the circulating fibrocytes in iridial regenerative processes.

The role of clear lens extraction in angle closure glaucoma

Clear lens extraction can be considered a therapeutic option in angle closure glaucoma (ACG). Even if it does not represent the first choice of treatment, it can be taken into consideration when the topical treatment does not control the intraocular pressure (IOP) and iridotomy does not have a positive effect on the angle closure, especially in appositional angle closure when biometry or ultrabiomicroscopy (UBM) show lens involvement. In angle closure glaucoma, clear lens extraction represents an etiological treatment that takes into account the role of the lens in the pathogenesis of the disease. If we ignore it and we choose a filtrating surgery as therapeutic option we can end up with complications such as prolonged athalamia, corneal damage and lens opacification that will eventually require cataract surgery, but performed late and with higher risks. Before performing a filtrating surgery in ACG, we should take an UBM. We also need to choose the best moment to perform surgery, after topical treatment and iridotomy have been tested, but before trabecular damage appears.