Abstract
Purpose :
The murine ocular graft versus host disease (OGvHD) model is a well-established model of human OGvHD that develops following allogeneic hematopoetic stem cell transplantation (HSCT). The objective of this study was to optimize the total body irradiation (TBI) protocol in the murine OGvHD model when using X-RAD 320 irradiator to allow sufficient ablation of the recipient bone marrow (BM) while minimizing the ocular and systemic effects of acute radiation toxicity.
Methods :
The major histocompatibility mismatch chronic OGvHD murine model was created, as described by Perez (2016; doi: 10.1016/j.bbmt.2016.07.012). Animal use was approved by the NC State University IACUC. BM from male C57BL/6 mice, 6-8 weeks of age, was collected from the femurs, tibias, and humeri then depleted of red blood cells and T cells. Splenocytes were collected, red blood cells were lysed, and remaining cells analyzed by flow cytometry. Female BALB/c mice, aged 6-8 weeks, were placed into an X-RAD irradiator (Accela, Inc.) programed at 320 Kv and 12.5 mA and administered 650 cGy (n=10), 700 cGy (n=4), or 750 cGy (n=10) x-ray TBI. Two hours after irradiation, mice were injected intravenously with 1x107 BM cells and 1x106 splenocytes. Following injection, body weights and tear production (phenol red test) were recorded, and scores (0-4) of the eyelid margins and corneal opacity were collected through day 42 after transplantation.
Results :
By day 40 after TBI, mean body weight of the 650, 700, and 750 cGy groups decreased 19.27%, 8.66%, and 16.69% respectively. Mortality rates of these groups were 20%, 0%, and 50% respectively. Eyelid margins had immediate elevation in scores by day 1-3 in the 700 and 750 cGy groups, while corneal scores were elevated in the 700 and 750 cGy groups by day 8-9. Eyelid and corneal scores did not increase with 650 cGy until day 21. There was no significant difference in tear production between these groups.
Conclusions :
OGvHD clinical findings appear to develop at approximately 21 days after TBI and HSCT, reagrdless of dose of TBI. However, TBI dose >650 cGy resulted in acute radiation induced ocular changes noted within the first week after TBI in addition to a higher body weight loss and mortality rate. To minimize TBI acute radiation ocular signs, which may confound interpretation of treatment effects, TBI x-ray radiation dose of less than 700 cGY is recommended.
This is a 2021 ARVO Annual Meeting abstract.