The protective effect of Dendrobium officinale polysaccharides on photoaging fibroblasts by scavenging reactive oxygen species and promoting the expression of TGF-β1

The purpose of this study was to explore the protective effect of Dendrobium officinale polysaccharides （DOP） onphotoaging human skin fibroblasts and its specific mechanism of action. The photoaging fibroblast model wasestablished by ultraviolet B （UVB） irradiation. The toxic effects of different concentrations of DOP were detected usingMTT. Senescent cells were detected using a β-galactosidase kit. Reactive oxygen species （ROS） in cells were detectedusing a flow cytometer. The expression of matrix metalloproteinase-1 （MMP-1）, type I collagen C-terminal peptide（CICP）, and transforming growth factor β-1 （TGF-β1） in spent culture medium was detected by ELISA. The resultsshowed that the low concentration of DOP （20, 40, 80 μg/mL） had no cytotoxicity on fibroblasts. After 60 mJ/cm2UVBirradiation, the number of aging β-gal-positive cells increased, the levels of CICP and TGF-β1 in spent culture mediumdecreased, while the levels of MMP-1 and ROS increased. After administration of DOP on photoaging fibroblasts, thenumber of aging β-gal-positive cells decreased, the levels of ROS and MMP-1 decreased, and the levels of TGF-β1 andCICP increased. This experiment suggests that DOP has the effect of removing ROS induced by UVB, regulating thebalance of collagen production and degradation, and protecting photoaging human skin fibroblasts.

Beta-nerve growth factor promotes neurogenesis and angiogenesis during the repair of bone defects

We previously showed that the repair of bone defects is regulated by neural and vascular signals. In the present study, we examined the effect of topically applied β-nerve growth factor（β-NGF） on neurogenesis and angiogenesis in critical-sized bone defects filled with collagen bone substitute. We created two symmetrical defects, 2.5 mm in diameter, on either side of the parietal bone of the skull, and filled them with bone substitute. Subcutaneously implanted osmotic pumps were used to infuse 10 μgβ-NGF in PBS（β-NGF ＋ PBS） into the right-hand side defect, and PBS into the left（control） defect, over the 7 days following surgery. Immunohistochemical staining and hematoxylin-eosin staining were carried out at 3, 7, 14, 21 and 28 days postoperatively. On day 7, expression of β III-tubulin was lower on the β-NGF ＋ PBS side than on the control side, and that of neurofilament 160 was greater. On day 14, β III-tubulin and protein gene product 9.5 were greater on the β-NGF ＋ PBS side than on the control side. Vascular endothelial growth factor expression was greater on the experimental side than the control side at 7 days, and vascular endothelial growth factor receptor 2 expression was elevated on days 14 and 21, but lower than control levels on day 28. However, no difference in the number of blood vessels was observed between sides. Our results indicate that topical application of β-NGF promoted neurogenesis, and may modulate angiogenesis by promoting nerve regeneration in collagen bone substitute-filled defects.

Biocompatibility evaluation in vitro. Part II: Functional expression of human and animal osteoblasts on the biomaterials

DNA synthesis and collagen formations on the implant material by cell culture in vitro are the most important phenotypical expression to estimate the biocompatibility. In this part, DNA synthesis and collagen formation on implant materials were quantitatively and qualitatively estimated by radioactive isotope H + thymidine to incorporate into DNA chains, H + proline to incorporate into type I collagen proteins followed by scin tillation counting and antibody antigen immunocytochemistry staining, respectively. Research results demonstrate that hydroxyapatite (HA) stimulates DNA synthesis and collagen formation on the material whereas this stimulation is restricted by adding spinel to the materials. There are statistical differences between the influences of material components on both DNA synthesis and collagen formation. It is supposed that porous materials can supply more platforms for cell anchoring, and more DNA and collagen are synthesised on the porous materials. Immersion in culture medium results in new HA crystal formation on the porous HA materials.

Identification of LRRC46 as a novel candidate gene for high myopia

High myopia(HM)is the primary cause of blindness,with the microstructural organization and composition of collagenous fibers in the cornea and sclera playing a crucial role in the biomechanical behavior of these tissues.In a previously reported myopic linkage region,MYP5(17q21-22),a potential candidate gene,LRRC46(c.C235T,p.Q79X),was identified in a large Han Chinese pedigree.LRRC46 is expressed in various eye tissues in humans and mice,including the retina,cornea,and sclera.In subsequent cell experiments,the mutation(c.C235T)decreased the expression of LRRC46 protein in human corneal epithelial cells(HCE-T).Further investigation revealed that Lrrc46^(-/-)mice(KO)exhibited a classical myopia phenotype.The thickness of the cornea and sclera in KO mice became thinner and more pronounced with age,the activity of limbal stem cells decreased,and microstructural changes were observed in the fibroblasts of the sclera and cornea.We performed RNA-seq on scleral and corneal tissues of KO and normal control wild-type(WT)mice,which indicated a significant downregulation of the collagen synthesis-related pathway(extracellular matrix,ECM)in KO mice.Subsequent in vitro studies further indicated that LRRC46,a member of the important LRR protein family,primarily affected the formation of collagens.This study suggested that LRRC46 is a novel candidate gene for HM,influencing collagen protein VⅢ(Col8a1)formation in the eye and gradually altering the biomechanical structure of the cornea and sclera,thereby promoting the occurrence and development of HM.