Lesioni degenerative e meccanismi di riparo della superficie oculare: lo pterigio e le deficienze delle cellule staminali del limbo (LSCD). Studio immunoistochimico e tecniche di coltura cellulare

Pterygium is a surface ocular lesion that is associated with chronic UV exposure, characterized by proliferation, inflammatory infiltrates, fibrosis, angiogenesis and extracellular matrix remodeling. The Angiotensin converting enzyme (ACE or ACE I) is the major component of the Renin-angiotensin system (RAS) converting the inactive decapeptide Angiotensin I (Ang I) to the active octapeptide Angiotensin II (Ang II). Besides this “classical role”, it can act as transcriptional regulator in response to external stimuli that may lead to cell damage and tissue remodeling. Due to this role, it can be internalized into the nuclear compartment to act as transcriptional factor for proteins involved in the inflammatory response. The aim of the present study was to determine ACE expression and localization in pterygium and culture pterygium cells by immunohistochemistry. The results demonstrated nuclear immunolocalization of ACE in pterygium compared to normal conjunctival in histological sections. ACE was not detected in the nuclei of subcultivated pterygium epithelial cells. The nuclear localization of ACE may be correlated with an anti-inflammatory path mediated by activation of its transcriptional role. The human ocular surface is characterized by a continuous non-keratinized epithelium providing the eye with its first line of defense against infection and trauma. Corneal epithelial integrity and transparency are maintained by the stem cells (SCs) that reside in the limbus. However, when the limbus is extensively damaged, stem cell activity is compromised, resulting in a condition known as limbal stem cell deficiency (LSCD). This disease is characterized by corneal neovascularization, conjunctival epithelial ingrowth, chronic inflammation which impair vision. The aim of this study was to reconstruct in vitro organ culture models of human hemi-corneas (epithelium+stroma) on amniotic membrane, using primary keratocytes and limbal stem cells derived by human cornea. The results demonstrated that the complex represented by a well-differentiated epithelium taken together with a model resembling stroma, has developed on the surface of these hemi-corneas. Further investigation will be necessary to validate these models of hemi-corneas for pharmacotoxicology testing and therapeutic applications.