Kinetics of Angiogenic Responses in Corneal Transplantation

Abstract

Purpose To delineate and compare the kinetics of corneal angiogenesis after high-risk (HR) versus low-risk (LR) corneal transplantation. Methods In mice intrastromal sutures were placed in the recipient graft bed two weeks before allogeneic transplantation to induce angiogenesis and amplify the risk for graft rejection. Control (LR) graft recipients did not undergo suture placement, and thus the host bed remained avascular at the time of transplantation. Graft hemangiogenesis and opacity scores were evaluated for 8 weeks by slit-lamp biomicroscopy. Immunohistochemistry was used to measure CD31hi (blood vessels) and LYVE-1hi (lymphatic vessels) cells. Results A biphasic kinetics was observed for hemangiogenesis in both HR and LR transplant recipients using clinical and immunohistochemical assessments. The biphasic kinetics was composed of a rise-fall (phase 1) followed by a second rise (phase 2) in the degree of vessels. Compared to LR recipients, HR recipients showed higher hemangiogenesis (whole cornea and graft) throughout 8 weeks. Analyzing grafts revealed sustained presence of lymphatic vessels in HR recipients; however, lymphatic neovessels regressed in LR recipients two weeks post-transplantation. In contrast to HR host beds, the LR host bed microenvironment cannot sustain the growth of lymphatic neovessels in allografts while it can sustain continued hemangiogenesis. Conclusion The sustained presence of lymphatic vessels in the HR host beds can facilitate host immunity against allografts and is likely associated with ongoing higher risk of rejection of these grafts in long-term, suggesting that therapeutic interventions targeting inflammation and lymphatic vessels need to be sustained long-term in the HR corneal transplant setting.

Regulatory T cells promote corneal endothelial cell survival following transplantation via interleukin-10

“…[43][44][45][46] For the low-risk model, C57BL/6 donor corneas were grafted onto normal BALB/c host beds. [43][44][45][46] For the low-risk model, C57BL/6 donor corneas were grafted onto normal BALB/c host beds.…”

“…Two well-established models of allogeneic corneal transplantation were used, as described previously. [43][44][45][46] For the low-risk model, C57BL/6 donor corneas were grafted onto normal BALB/c host beds. For the high-risk model, 3 intrastromal 11-0 sutures were placed in the central cornea of BALB/c recipient mice 14 days prior to transplantation to induce an inflamed and vascularized host bed.…”

“…A standard protocol for murine orthotopic corneal transplantation was followed, as described previously. [43][44][45][46] Briefly, a 2-mm central corneal button was excised from donor C57BL/6 mice, grafted onto a 1.5-mm BALB/c recipient bed, and secured with 8 interrupted 11-0 nylon sutures. All procedures were performed with mice under anesthesia with intraperitoneal injection of ketamine (120 mg/kg) and xylazine (20 mg/kg).…”

Regulation of matrix metalloproteinases 2 and 9 in corneal neovascularization

“…CNV is most likely to lead to serious consequences, such as corneal scarring, edema, lipid deposition, and even vision loss Cursiefen et al, 2012;Yoon et al, 2005). Particularly, allograft transplantation can be at high risk in corneas of angiogenesis for immunologic rejection (Di Zazzo, Kheirkhah, Abud, Goyal, & Dana, 2017;Inomata et al, 2017;Zhong et al, 2018).…”

A New Immunotherapy Using Regulatory T-Cells for High-Risk Corneal Transplantation

“…Inflamed, neovascularized (ʻhigh-riskʼ) host beds were created using three intrastromal sutures placement into the central cornea using 11-0 nylon sutures 14 days before corneal transplantation to induce host beds prone to graft rejection. For confirming the neovascularization and lymphoangiogenessis in the cornea, we developed original software using ImageJ We have confirmed significantly high neovascularization and lymphoangiogenessis in high-risk host beds 14 days after suture placement 10) . Then, we excised a 1.5 mm corneal button from the high-risk host beds and performed the corneal transplantation with 2.0 mm donor corneas via 8 sutures using 11-0 nylon suture.…”