Injectable Quercetin-Loaded Hydrogel with Cartilage-Protection and Immunomodulatory Properties for Articular Cartilage Repair.

Articular cartilage plays an important role in human body. How to repair articular cartilage defects when they appear due to various factors has always been a major clinical challenge. Recently, studies have shown that slowing the degradation of cartilage extracellular matrix (ECM) and modulating the inflammatory response of the host thereby promoting cartilage tissue regeneration are important in the cartilage repair process. In this study, a drug-loaded injectable hydrogel was constructed for repairing articular cartilage. This hydrogel could not only maintain the phenotype of chondrocytes but also regulate the inflammatory response of the host. The injectable sodium alginate (SA)/bioglass (BG) hydrogel was mixed with the injectable thermal-responsive SA/agarose (AG)/quercetin (Que) hydrogel to obtain an injectable hydrogel containing both Que and BG (Que-BG hydrogel) for articular cartilage regeneration. The Que-BG hydrogel has a proper swelling ratio that can promote integration between the formed tissue and host tissue, and it allows Que to release slowly in situ to improve its bioavailability. The Que-BG hydrogel could upregulate SRY-box 9 (SOX9), aggrecan (ACAN), and collagen type II alpha 1 chain (COL2A1) of normal chondrocytes to maintain the normal chondrocyte phenotype. In addition, it could promote macrophage M2 polarization, reduce inflammation, and inhibit ECM degradation by downregulating the expression of inducible nitric oxide synthase (iNOS), matrix metalloproteinase-13 (MMP13), and matrix metalloproteinase-1 (MMP1) in degenerative chondrocytes. After injecting the Que-BG hydrogel into a rat cartilage defect model, the formed tissue was observed to be similar to the normal tissue and was highly integrated with the surrounding tissue. Therefore, the injectable Que-BG hydrogel improves Que bioavailability, maintains chondrocyte phenotype, inhibits ECM degradation, and reduces inflammatory response.

Enhancement of tendon­bone healing following rotator cuff repair using hydroxyapatite with TGFß1.

The formation of fibrocartilage at the healing site following a rotator cuff tear repair is a major problem in the field of tendon­bone healing. The present study aimed to enhance the healing of the tendon­bone interface following rotator­cuff tear repair by the interposition of hydroxyapatite (HA) encapsulated with transforming growth factor ß1 (TGFß1). Using an acute rotator cuff repair model, rats were divided into three groups: i) Repair only (control); ii) HA group; and iii) HA­TGFß1 group. Animals were sacrificed at 2, 4 and 8 weeks following surgery. Micro­computed tomography (CT), histomorphometric analyses and biomechanical tests were used to evaluate the supraspinatus tendon­bone complex. The micro­CT images revealed notable novel bone formation in the groups treated with HA­TGFß1. The histomorphometric analyses demonstrated improved fibrocartilage formation and collagen organization at the tendon­bone interface. The HA­TGFß1 combination significantly improved the area of fibrocartilage, particularly at early time points (2 and 4 weeks). There was a significantly greater load­to­failure force achieved in the HA and HA­TGFß1 groups compared with the control group at 4 and 8 weeks. Augmentation of the ceramic powder with HA­TGFß1 at the tendon­bone interface was demonstrated to strengthen the healing entheses, increase bone and fibrocartilage formation and improve collagen organization compared with surgical repair alone. Local application of HA­TGFß1 demonstrates potential in improving tendon­bone healing following rotator cuff repair.

Change and significance of nuclear factor-kappaB in adriamycin induced cardiomyopathy in rats.

BACKGROUND: This study aimed at investigating the change and significance of nuclear factor-kappaB (NF-kappaB) in cardiomyopathy induced by adriamycin (ADR) in rats. METHODS: Sixty male Wistar rats were randomly divided into three groups: control, ADR and ADR + pyrrolidine dithiocarbamate (PDTC) groups. After 30-day experiment, myocardial histopathological observation was performed. Location and distribution of NF-kappaB p50 was examined by immunohistochemical assay. Expression of NF-kappaB p50 protein was examined by immunobolt assay. Electrophoretic Mobility Shift Assay examined activity of NF-kappaB; Myocardium p53 gene expression was examined by RT-PCR analysis. RESULTS: The myocardial lesions of rats were less pronounced in ADR + PDTC group than in ADR group. Compared with control group, there were many myocardium nucleuses, which expressed NF-kappaB p50 and distribute under epicardium. Expression of NF-kappaB p50 protein in nucleus increased significantly in ADR group. The NF-kappaB binding activity increased significantly in ADR group. Myocardium expressions of p53 mRNA increased in ADR group. CONCLUSIONS: The NF-kappaB binding activity increased significantly in cardiomyopathy induced by ADR in rats. Moreover, NF-kappaB plays an important role in causing degeneration of myocardial tissue and regulating expression of related-apoptosis genes.

Purification and characterization of the human erythrocyte band 3 protein C-terminal domain.

To clarify the function of the hydrophilic carboxyl-terminal tail of human erythrocyte membrane band 3 protein (HEM-B3), we purified two peptides, C1 (Ala893-Val911) and KS4 (Gly647-Arg656), from human erythrocyte band 3 protein preparations. Purified C1 peptides at concentrations from 5 to 80 microM were incubated with fresh human erythrocyte white ghosts. The C1 peptide demonstrated a novel protease activity, which cleaved glycophorin A (GPA) at Leu118-Ser119 in a dose-dependent manner. This activity was eliminated by trypsin. In a control experiment, the KS4 peptide did not cleave GPA under the same conditions. To help substantiate that the band 3 C-terminal tail peptide (C1) alone possesses the protease activity, two experiments were performed. First, the plasmids pGBKT(7)-GPA-Ct and pGADT(7)-AE1-Ct were cotransformed into the yeast strain AH109. The pGBKT(7)-GPA-Ct plasmid contains the cDNA of the 33 amino acid residue section of GPA (Tyr93-Asn125) fused with the pGBKT(7) vector. The plasmid pGADT(7)-AE1-Ct contains the cDNA of the C-terminal 33 amino acid residues of HEM-B3 fused with the GAL4 DNA-binding domain in the pGADT(7) vector. The results of the cotransformation experiment indicated that the C-terminal 33 amino acid residues of HEM-B3 interacted directly with the GPA C-terminal segment defined above. Second, we used a mammalian two-hybrid analysis to confirm the interaction relationship between the band 3 C-terminal segment and the GPA C-terminus. The C-terminus of GPA and the C-terminal 33 amino acid residues of HEM-B3 were subcloned into the DNA-binding domain and transcription activation domain vectors of the two-hybrid system, respectively. They were then cotransfected along with a chloramphenicol acetyltransferse (CAT) reporter vector into HeLa cells. The CAT activity measured in this experiment also indicated that there was interaction between the C-terminal 33 amino acid residues of HEM-B3 and the C-terminus of GPA.