Investigation of comet assays under conditions mimicking ocular instillation administration in a three-dimensional reconstructed human corneal epithelial model.

Purpose: A comet assay is one of the genotoxicity methods for evaluating the potential of chemicals to induce DNA strand breaks. To investigate the usefulness of comet assays for evaluating the genotoxic potential of ophthalmic solutions, a three-dimensional (3D) reconstructed human corneal epithelial model (3D corneal model) was exposed to conditions mimicking topical ocular instillation administration. Methods: The 3D corneal model was exposed to acridine orange, ethidium bromide, hydrogen peroxide, 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat), 4-nitroquinoline 1-oxide (4-NQO), acrylamide and methyl methanesulfonate (MMS). To mimic the ocular surface condition to which ophthalmic solutions are administered, the exposure time was set to 1 minute. Likewise, human corneal epithelial (HCE-T) cells, as monolayer cultured cells, were exposed to the same chemicals, for comparison. Results: In the 3D corneal model, the amount of DNA fragments was statistically significantly increased in cells treated with each of the test chemicals except acrylamide. In HCE-T cells, the amount of DNA fragments was statistically significantly increased in acridine orange-, ethidium bromide-, hydrogen peroxide-, 4-NQO- and MMS-treated cells but not in paraquat- or acrylamide-treated cells. In the 3D corneal model, the lowest concentrations at which we observed DNA damage were about 100 times higher than the concentrations in HCE-T cells. Since the 3D corneal model is morphologically similar to human corneal tissue, form a multilayer and having tight junctions, it may be that the test chemicals only permeated about 1% into the 3D corneal model. Conclusion: These results suggest that the comet assay using 3D cell culture models may reflect in vivo conditions better than do monolayer cultured cells, and that the comet assay may be useful for the evaluation of genotoxic potential of topical ophthalmic solution.

Intramuscular transplantation of G-CSF-mobilized CD34(+) cells in patients with critical limb ischemia: a phase I/IIa, multicenter, single-blinded, dose-escalation clinical trial.

A number of preclinical studies have indicated the therapeutic potential of endothelial progenitor cells for vascular regeneration in ischemic diseases. A phase I/IIa clinical trial of transplantation of autologous CD34(+) cells, the endothelial and hematopoietic progenitor-enriched fraction, was performed in no-option patients with atherosclerotic peripheral artery disease or Buerger's disease with critical limb ischemia (CLI). CD34(+) cells were isolated from the G-CSF-mobilized apheresis product using a magnetic cell sorting system. CD34(+) cells (10(5)/kg, n = 6; 5 x 10(5)/kg, n = 8; or 10(6)/kg, n = 3) were injected i.m. into the leg with more severe ischemia. The Efficacy Score, representing changes in the toe brachial pressure index (TBPI), Wong-Baker FACES pain rating scale, and total walking distance 12 weeks after cell transplantation, the primary endpoint, was positive, indicating improvement in limb ischemia in all patients, although no significant dose-response relationship was observed. During the 12-week observation after cell therapy, the Wong-Baker FACES pain rating scale, TBPI, transcutaneous partial oxygen pressure, total or pain-free walking distance, and ulcer size serially improved in all patients. No death or major amputation occurred, and severe adverse events were rare, although mild to moderate events relating to G-CSF and leukapheresis were frequent during the 12-week follow-up. In conclusion, the outcomes of this prospective clinical study indicate the safety and feasibility of CD34(+) cell therapy in patients with CLI. Favorable trends in efficacy parameters encourage a randomized and controlled trial in the future.

Dose-dependent contribution of CD34-positive cell transplantation to concurrent vasculogenesis and cardiomyogenesis for functional regenerative recovery after myocardial infarction.

BACKGROUND: Multilineage developmental capacity of the CD34+ cells, especially into cardiomyocytes and smooth muscle cells (SMCs), is still controversial. In the present study we performed a series of experiments to prove our hypothesis that vasculogenesis and cardiomyogenesis after myocardial infarction (MI) may be dose-dependently enhanced after CD34+ cell transplantation. METHODS AND RESULTS: Peripheral blood CD34+ cells were isolated from total mononuclear cells of patients with limb ischemia by apheresis after 5-day administration of granulocyte colony-stimulating factor. PBS and 1x10(3) (low), 1x10(5) (mid), or 5x10(5) (high) CD34+ cells were intramyocardially transplanted after ligation of the left anterior descending coronary artery of nude rats. Functional assessments with the use of echocardiography and a microtip conductance catheter at day 28 revealed dose-dependent preservation of left ventricular function by CD34+ cell transplantation. Necropsy examination disclosed dose-dependent augmentation of capillary density and dose-dependent inhibition of left ventricular fibrosis. Immunohistochemistry for human-specific brain natriuretic peptide demonstrated that human cardiomyocytes were dose-dependently observed in ischemic myocardium at day 28 (high, 2480+/-149; mid, 1860+/-141; low, 423+/-9; PBS, 0+/-0/mm2; P<0.05 for high versus mid and mid versus low). Immunostaining for smooth muscle actin and human leukocyte antigen or Ulex europaeus lectin type 1 also revealed dose-dependent vasculogenesis by endothelial cell and SMC development after CD34+ cell transplantation. Reverse transcriptase-polymerase chain reaction indicated that human-specific gene expression of cardiomyocyte (brain natriuretic peptide, cardiac troponin-I, myosin heavy chain, and Nkx 2.5), SMC (smooth muscle actin and sm22alpha), and endothelial cell (CD31 and KDR) markers were dose-dependently augmented in MI tissue. CONCLUSIONS: Human CD34+ cell transplantation may have significant and dose-dependent potential for vasculogenesis and cardiomyogenesis with functional recovery from MI.