Endothelial progenitor cells transfected with PDGF: cellular and molecular targets for prevention of diabetic microangiopathy

Transcatheter Arterial Infusion of Autologous CD133(+) Cells for Diabetic Peripheral Artery Disease

Microvascular lesion in diabetic peripheral arterial disease (PAD) still cannot be resolved by current surgical and interventional technique. Endothelial cells have the therapeutic potential to cure microvascular lesion. To evaluate the efficacy and immune-regulatory impact of intra-arterial infusion of autologous CD133(+) cells, we recruited 53 patients with diabetic PAD (27 of CD133(+) group and 26 of control group). CD133(+) cells enriched from patients' PB-MNCs were reinfused intra-arterially. The ulcer healing followed up till 18 months was 100% (3/3) in CD133(+) group and 60% (3/5) in control group. The amputation rate was 0 (0/27) in CD133(+) group and 11.54% (3/26) in control group. Compared with the control group, TcPO2 and ABI showed obvious improvement at 18 months and significant increasing VEGF and decreasing IL-6 level in the CD133(+) group within 4 weeks. A reducing trend of proangiogenesis and anti-inflammatory regulation function at 4 weeks after the cells infusion was also found. These results indicated that autologous CD133(+) cell treatment can effectively improve the perfusion of morbid limb and exert proangiogenesis and anti-inflammatory immune-regulatory impacts by paracrine on tissue microenvironment. The CD133(+) progenitor cell therapy may be repeated at a fixed interval according to cell life span and immune-regulatory function.

Paradoxical effects of PDGF-BB overexpression in endothelial cells on engineered blood vessels in vivo

Therapeutic revascularization with either exogenous angiogenic growth factors or vascular cells has yet to demonstrate efficacy in the clinic. Injection of angiogenic growth factors often produces unstable and abnormal blood vessels. Blood vascular networks derived from implanted endothelial cells persist only transiently due to the insufficient recruitment of perivascular cells. We hypothesize that a combination of the two approaches may act synergistically to yield a better result. To enhance the recruitment of perivascular cells, human umbilical vein endothelial cells were genetically modified to overexpress platelet-derived growth factor (PDGF)-BB. PDGF-BB overexpression promoted both proliferation and migration of perivascular precursor cells (10T1/2 cells) in vitro. When mock-infected endothelial cells were implanted alone in vivo, they formed transient blood vascular networks that regressed by day 30. PDGF-BB overexpression enhanced the survival of endothelial cells in vivo. However, the PDGF-BB-expressing vessel network failed to establish patent blood flow. Co-implantation of PDGF-BB-overexpressing endothelial cells with 10T1/2 cells paradoxically resulted in the rapid regression of the vascular networks in vivo. PDGF-BB stimulated the expression of both chemokine (C-C motif) ligand 2 (CCL2) and CCL7 in 10T1/2 cells and led to the increased accumulation of macrophages in vivo. These results suggest a potential negative interaction between angiogenic growth factors and vascular cells; their use in combination should be carefully tested in vivo for such opposing effects.

Identification and clinical significance of mobilized endothelial progenitor cells in tumor vasculogenesis of hepatocellular carcinoma

PURPOSE

To investigate the distribution, frequency, and clinical significance of mobilized endothelial progenitor cells (EPC) in hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

In healthy controls and patients with HCC, the frequency of circulating EPCs was determined by colony-forming assays, fluorescence-activated cell sorting, and real-time PCR. One hundred sixty-five--amino acid form of vascular endothelial growth factor and platelet-derived growth factor-BB in plasma and tissue were quantified by ELISA. The distribution and frequency of EPCs were evaluated by immunofluorescence, immunohistochemistry, and real-time PCR in normal liver (n = 8), and tumor tissue (TT), adjacent nonmalignant liver tissue (AT), and tumor-free tissue 5 cm from the tumor edge (TF) from 64 patients with HCC. Clinicopathologic data for these patients were evaluated.

RESULTS

Compared with values for healthy controls, colony-forming unit scores were higher in the peripheral blood of patients with HCC. Plasma 165-amino acid form of vascular endothelial growth factor and platelet-derived growth factor-BB correlated with the expression level of the AC133 gene, which was also higher in the peripheral blood of patients with HCC. Immunohistochemical analysis showed that EPCs were incorporated into the microvessels in cirrhotic and tumor tissue. Compared with normal liver (9.00), increased AC133(+) microvessel density (microvessels/0.74 mm(2)) was found in TT (53.56), AT (84.76), and TF (48.33). The levels of AC133 gene expression and AC133-microvessel density in AT, which were the highest among four groups, correlated with clinicopathologic variables (the absence of tumor capsule, venous invasion, proliferating cell nuclear antigen intensity, and early recurrence).

CONCLUSIONS

Mobilized EPCs participate in tumor vasculogenesis of HCC. AC133 gene or antigen in peripheral blood and liver tissue could be used as a biomarker for predicting the progression of HCC.