ABSTRACT
Histone modification plays an important role in the process of cellular DNA damage repair. In recent years, a great number of studies have shown that histone modification affectsradiation responses including recruitment of DNA damage repair factors, creation of chromatin open structures and establishment of repressive histone marks.Regulation of histone modification may influence the process of DNA damage repair and thus affect radiation sensitivity. In this paper, the effects of histone modification on DNA damage repair, cellular radiosensitivity and the underlying mechanisms are reviewed.
ABSTRACT
Objective To fabricate a novel tissue-engineered cartilage with adipose-derived stem cells (ADSCs) seeded on the chitosan hydrogel scaffold to repair articular cartilage defect.Methods Adipose tissue and costal cartilage were harvested from New Zealand rabbits,and ADSCs in passage one and chondrocytes were obtained after the samples were digested and cultured in vitro.ADSCs were digested,suspended,seeded onto the sterile chitosan gel,and cultured in vitro for 1 week to fabricate the tissue-engineered cartilage.The defects were respectively filled with the tissue-engineered cartilage (composite group),chondrocyte suspension (cell group),chitosan gel (material group) and nothing at all (control group).At postoperative 12 weeks,cartilage repair was evaluated using the gross examination,histological staining,immunohistochemical staining and international cartilage repair society (ICRS) histological score.Results Effect of cartilage repair in composite group was significantly better compared to other groups.The regenerated tissue in composite group seemed tightly bound in normal tissue,with similar structure and extracellular matrix secretion.ICRS histological score in composite group was (13.89 ± 0.14) points,which differed significantly from (7.06 ± 0.19) points in control group,(7.14 ± 0.22) points in cell group and (7.46 ± 0.26) points in material group (P ＜0.01).Conclusion The tissue-engineered cartilage with ADSCs seeded onto the chitosan hydrogel is effective for repair of articular cartilage defect.