New characterization and safety evaluation of human limbal stem cells used in clinical application: fidelity of mitotic process and mitotic spindle morphologies.

BACKGROUND: Limbal stem cells (LSCs) are crucial for the regeneration of the corneal epithelium in patients with limbal stem cell deficiency (LSCD). Thus, LSCs during cultivation in vitro should be in highly homogeneous amounts, while potency and expression of stemness without tumorigenesis would be desirable. Therefore, further characterization and safety evaluation of engineered limbal grafts is required to provide safe and high-quality therapeutic applications. METHODS: After in vitro expansion, LSCs undergo laboratory characterization in a single-cell suspension, cell culture, and in limbal grafts before transplantation. Using a clinically applicable protocol, the data collected on LSCs at passage 1 were summarized, including: identity (cell size, morphology); potency (yield, viability, population doubling time, colony-forming efficiency); expression of putative stem cell markers through flow cytometry, immunofluorescence, and immunohistochemistry. Then, mitotic chromosome stability and normal mitotic outcomes were explored by using live-cell imaging. Finally, impurities, bacterial endotoxins and sterility were determined. RESULTS: Expression of the stemness marker p63 in single-cell suspension and in cell culture showed high values by different methods. Limbal grafts showed p63-positive cells (78.7 ± 9.4%), Ki67 proliferation (41.7 ± 15.9%), while CK3 was negative. Impurity with 3T3 feeder cells and endotoxins was minimized. We presented mitotic spindles with a length of 11.40 ± 0.54 m and a spindle width of 8.05 ± 0.55 m as new characterization in LSC culture. Additionally, live-cell imaging of LSCs (n = 873) was performed, and only a small fraction < 2.5% of aberrant interphase cells was observed; 2.12 ± 2.10% of mitotic spindles exhibited a multipolar phenotype during metaphase, and 3.84 ± 3.77% of anaphase cells had a DNA signal present within the spindle midzone, indicating a chromosome bridge or lagging chromosome phenotype. CONCLUSION: This manuscript provides, for the first time, detailed characterization of the parameters of fidelity of the mitotic process and mitotic spindle morphologies of LSCs used in a direct clinical application. Our data show that p63-positive CK3-negative LSCs grown in vitro for clinical purposes undergo mitotic processes with extremely high fidelity, suggesting high karyotype stability. This finding confirms LSCs as a high-quality and safe therapy for eye regeneration in humans.

The level of serum pro-matrix metalloproteinase-2 as a prognostic factor in patients with invasive ductal breast cancer.

This paper analyses data of 150 female patients undergoing surgical treatment for invasive ductal breast cancer at the University Hospital for Tumors from January 2006 to January 2007. The control group consisted of 50 healthy women. The patients were classified into three groups, depending on their tumor differentiation, i.e. grade I, II and III tumor groups. Each group consisted of 50 patients. Traditional prognostic factors including: age, tumor size and differentiation grade, axillary lymph node status, presence of distant metastases, steroid receptor findings, vascular invasion of the primary tumor, presence of an extensive intraductal component (EIC) in the primary tumor, HER-2 protein expression were evaluated. Both the patients' and controls' serum levels of proMMP-2 (pro-matrix metalloproteinase-2) were assessed using the ELISA method. The aim of the study was to assess pathohistological prognostic factors and the level of serum proMMP-2 in the three patient groups and the controls, compare the relationship between the prognostic factors and the level of serum proMMP-2 in the patient groups, and upon the results, determine possible features of proMMP-2 as a prognostic factor in breast cancer patients. The study results showed no difference in proMMP-2 concentrations between the three patient groups and the controls. No statistically significant difference in the serum proMMP-2 concentration was found between the patient groups, although the grade III group values were the highest showing a trend toward statistical significance. Comparison of proMMP-2 and prognostic factors revealed a statistically significant correlation between proMMP-2 and age in patients with histologic grade I tumors. There was no statistically significant correlation between circulating proMMP-2 and other pathohistological prognostic factors.