Feasibility of caffeic acid as a crosslinking agent in modifying acellular extracellular matrices.

Acellular extracellular matrices (aECM) are commonly utilized, both experimentally and clinically, in the regenerative medicine field. However, some disadvantages such as rapid degradation, poor mechanical properties, chronic inflammatory reactions and low antioxidant activity have limited their further application. In this study the feasibility of caffeic acid as a crosslinking agent in fixing small intestinal submucosa (SIS) was evaluated. The ninhydrin assay, swelling ratio and FTIR spectra indicated that caffeic acid can efficiently react with free amino groups to crosslink SIS and the highest crosslinking index reached 21.60 ± 1.37%. Moreover, the shrinkage temperature of SIS remarkably increased from 59 °C to about 80 °C and the degradation rate of CA-SIS was all lower than 6%, demonstrating their improved biostability and hydrothermal stability. Importantly, the antioxidant activity of CA-SIS ranged from 55% to 90%, statistically higher than that of native SIS (37.33 ± 2.94%). Additionally the cytotoxicity test presented that the cytotoxicity grade of CA-SIS was 1 or 0, whilst large numbers of living HUVECs were attached to the surface of the material and exhibited high cell viability. These results indicated their excellent cytocompatibility. The data of subcutaneous implant displayed that the number of inflammatory cells in 2%- and 2.5%CA-SIS groups remained at a low level (below 100 cells/field) while that of the native SIS group continued increasing, finally reaching 142.33 ± 30.92 cells/field. In conclusion, caffeic acid is a promising candidate for modifying aECM and may play a vital role in the design and fabrication of tissue engineering scaffolds.

Analysis of the expression and prognostic significance of DDK complex in Hepatocarcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) remains one of the most common and lethal malignancies worldwide. Although DBF4-dependent kinase (DDK) complex composed of CDC7 kinase and its regulatory subunit DBF4 has been shown to be overexpressed in primary tumors and promotes tumor development, while its role and prognostic value in HCC remain largely unknown. In the present study, the expression of DBF4 and CDC7 and their relationship with clinical characteristics were comprehensively analyzed. METHODS: The mRNA expression profiles of HCC and the corresponding clinical data of HCC patients were downloaded from TCGA and GEO databases, respectively. The differences in DBF4 and CDC7 expression in tumor tissues and adjacent normal tissues were analyzed. HCC-derived tissue microarray (TMA) was used to evaluate and score the expression of CDC7 by immunohistochemistry (IHC) staining. The Kaplan-Meier method and the Cox regression method were used to analyze the relationship between overall survival and clinical characteristics of the patients. Gene set enrichment analysis (GSEA) was used to analyze the pathway enrichment of DBF4 and CDC7. RESULTS: DBF4 and CDC7 had similar expression patterns in HCC patients. Detailly, compared with adjacent tissues, both mRNA and protein of DBF4 and CDC7 were significantly higher in HCC, and their expression was positively correlated with AJCC_T stage, clinical stage and G stage (grade) of liver cancer patients, and higher DBF4 or CDC7 expression predicted a worse prognosis in HCC patients with shorter overall survival (OS), recurrence-free survival (RFS), disease-specific survival (DSS) and progress-free survival (PFS). Cox regression analysis suggested that both DBF4 and CDC7 were independent risk factors for the prognosis of HCC patients in TCGA dataset. GSEA suggested that both DBF4 and CDC7 were positively correlated with cell cycle and DNA replication. Finally, the prognostic value of CDC7 was furtherly confirmed by TMA-based IHC staining results. CONCLUSIONS: Our study showed that DDK complex was significantly increased in HCC. Both DBF4 and CDC7 may be potential diagnostic and prognostic markers for HCC, and high expression of DDK members predicts a worse prognosis in patients with HCC, which may be associated with high tumor cell proliferation rate.