Amniotic epithelial cells reverse abnormal vascular structure and function in endometrial carcinoma

The methods used to rebuild tumour vascular structure and function are called vascular normalization. Vascular normalization methods often block a single angiogenic molecular pathway, but tumor molecular pathways are interconnected and unstable. Since the vascular structure is not repaired, vascularity can be normalized only within a limited time. Amniotic epithelial cells (AECs) are used in tissue engineering to increase blood perfusion and promote wound healing. There have been no reports on the use of AECs in treatment to promote tumor vascular restoration.

The multipotential stem cell features of AECs were detected by immunofluorescence (IF), RT-PCR, and western blot. A nude rat in situ endometrial carcinoma model was developed. AECs were transfected with lentivirus-green fluorescent protein (GFP)-luciferase (Luc). The vascular formation abilities of AECs were monitored in vitro and in vivo under different conditions. AECs were injected by the rat tail vein, tumour vascular structural and perfusion changes were monitored, and the synergistic effects of AECs with cisplatin (DDP) chemotherapy were evaluated.

AECs expressed the stem cell markers OCT4, Nanog, and CK19 at high levels. AECs could differentiate into adipocytes, chondrocytes, and osteocytes. Lentiviral GFP-Luc was successfully transfected into AECs, and GFP-labelled AECs formed vascular tube-like structures and invaded tumor tissue to form vascular structures in vitro. Kinetic luciferase imaging confirmed that AECs homed to rat uterine tumor tissues after injection by the tail vein. After AEC injection, tumour vascular α-SMA/CD31 labelling increased in vascular pericytes, while detection of VEGF-A expression by ELISA decreased. Cadherin labelling showed that basement membrane integrity improved distinctly in the AEC group compared with that in the corresponding control group. Hoechst 33342 and ultrasound Doppler detection showed that tumor vascular perfusion was ameliorated; pimonidazole perfusion showed reduced tumour tissue anoxia, and FITC-dextran perfusion confirmed that vascular leakage was obviously reduced in the AEC group compared with that in the control group. Tumor apoptosis and the rat survival rate in the AEC + DDP group were further enhanced, as demonstrated by CD31 (or α-SMA) IF and GFP colocalization, as well as GFP western blot. AECs differentiated into tumor vascular endotheliocytes or pericytes and enhanced tumor vascular integrity.

AECs had the characteristics of pluripotent stem cells, and they could vascularize tissues under different conditions. AECs integrated into endometrial cancer vascular structures in nude rats, reduced dysregulated tumour angiogenesis, improved the efficiency of tumour vascular perfusion, and enhanced the cytotoxic effects of DDP. These findings provide a new method for the reconstruction of tumor vessels.