The Potential of Mesenchymal Stem/Stromal Cell Therapy in Mustard Keratopathy: Discovering New Roads to Combat Cellular Senescence

Abstract

Mesenchymal stem/stromal cells (MSCs) are considered a valuable option to treat ocular surface disorders such as mustard keratopathy (MK). MK often leads to vision impairment due to corneal opacification and neovascularization and cellular senescence seems to have a role in its pathophysiology. Herein, we utilized intrastromal MSC injections to treat MK. Thirty-two mice were divided into four groups based on the exposure to 20 mM or 40 mM concentrations of mustard and receiving the treatment or not. Mice were clinically and histopathologically examined. Histopathological evaluations were completed after the euthanasia of mice after four months and included hematoxylin and eosin (H&E), CK12, and beta-galactosidase (β-gal) staining. The treatment group demonstrated reduced opacity compared to the control group. While corneal neovascularization did not display significant variations between the groups, the control group did register higher numerical values. Histopathologically, reduced CK12 staining was detected in the control group. Additionally, β-gal staining areas were notably lower in the treatment group. Although the treated groups showed lower severity of fibrosis compared to the control groups, statistical difference was not significant. In conclusion, it seems that delivery of MSCs in MK has exhibited promising therapeutic results, notably in reducing corneal opacity. Furthermore, the significant reduction in the β-galactosidase staining area may point towards the promising anti-senescence potential of MSCs.

Mouse Model of Nitrogen Mustard Ocular Surface Injury Characterization and Sphingolipid Signaling

“…While undertaking this study, we found that other groups reported the development of mouse models of NM exposure in the last 2 years [23][24][25][26]. Clinical and histopathological characterization of these models suggested that they can recapitulate the injury reported in human and in vivo rabbit models.…”

“…The swelling of the eyes was improved with the discharge getting cleared by 14 DPI (Figure 1G); however, even at 35 DPI, the eyes were cloudy compared to the saline-treated eyes with loss of eyelashes (Figure 1 H,I). We observed this NM-induced entire ocular surface injury model demonstrate a longitudinal pathology with an early acute phase (1-6 DPI) that progressed into a late acute phase (7-14 DPI) and ultimately to a chronic phase (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). Identifying these sub-phases can help test and fine-tune the delivery window of drugs developed as MCMs against such injury.…”

“…However, damage to the eye of victims of either chemical warfare or accidental exposure will never be restricted to the center of the cornea, but the whole ocular surface will be exposed to the toxin. To recapitulate this condition experienced in a real-life situation, we developed a model of whole ocular surface injury, including the cornea, conjunctiva, and sclera, which is different from other recently developed mouse models of NM-mediated corneal injury [23][24][25][26], and this is the first report on characterizing NM-induced mouse ocular surface injury. We aimed to develop a model of moderate injury that would be useful to test MCM candidates.…”

“…While the saline-treated eyes consistently scored around 1, most NM-injured eyes ranged between 2.5 to 3.5 till 14 DPI and improved to ~1.5 in the next three weeks (Figure 1J). Based on this characterization, we divided the pathology into different stages: early acute (1-6 DPI), late acute (7-14 DPI), and chronic phases (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35). Taken together, the data suggested that we have successfully developed a mouse model NM-induced ocular surface injury that manifests similar eyelids and conjunctival inflammation and restricted eye openings as reported in in vivo rabbit models [39].…”

“…Clinical and histopathological characterization of these models suggested that they can recapitulate the injury reported in human and in vivo rabbit models. Some of the studies focused on the implication of cellular senescence [25] or the potential of mesenchymal stem cell (MSC) therapy following NM-induced keratopathy [26]. Some of these studies developed the model by placing filter paper soaked in an NM solution at the central cornea [23,24].…”