Hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC). However, very little is known about the replication of HBV in HCC tissues. We analyzed viral and cellular parameters in HCC (T) and nontumor liver (NT) samples from 99 hepatitis B surface antigen (HBsAg)-positive, virologically suppressed patients treated by tumor resection or liver transplantation. We examined total HBV DNA and RNA as well as covalently closed circular DNA (cccDNA) and pregenomic RNA (pgRNA), which are considered as markers of active HBV replication. Total HBV DNA and RNA were detected in both T and NT samples in a majority of cases, but only a subset of tumors harbored detectable levels of HBV cccDNA and pgRNA (39% and 67%) compared to NT livers (66% and 90%; P < 0.01). Further evidence for HBV replication in tumor tissues was provided by sequencing of the X gene derived from episomal forms, showing that HBV genotypes differed between T and matched NT samples in 11 cases. The detection of pgRNA and cccDNA in tumors was correlated to the absence of tumorous microvascular invasion and to better patient survival. Analysis of gene expression profiles by Agilent microarrays revealed that pgRNA-positive HCCs were characterized by low levels of cell cycle and DNA repair markers and expression of the HBV receptor, sodium taurocholate cotransporting polypeptide, indicating well-differentiated tumors. Conclusion: HCC replicating HBV represents a subtype of weakly invasive HCC with a transcriptomic signature. pgRNA originating from nonintegrated, complete HBV genomes is a sensitive marker for viral replication and prognosis. (HEPATOLOGY 2018;67:86-96). C hronic infection with hepatitis B virus (HBV)is a major cause of hepatocellular carcinoma (HCC). In the nucleus of hepatocytes, the relaxed circular double-stranded HBV-DNA genome (RC) is converted into covalently closed circular DNA (cccDNA), which is the template for viral RNA transcription. Among HBV mRNAs, 3.5-kb preC and pregenomic RNAs (pgRNA) originate from HBV cccDNA, and pgRNA is reverse transcribed to enable the synthesis of HBV DNA.In the absence of a dominant oncogene encoded by the HBV genome, indirect roles have been proposed, including the insertional activation of cancer-related genes through the integration of HBV-DNA sequences, (1) the induction of genetic instability by viral integration or expression of the hepatitis B X protein

The recent description of resident stem/progenitor cells in degenerated intervertebral discs (IVDs) supports the notion that their regenerative capacities could be harnessed to stimulate endogenous repair of the nucleus pulposus (NP). In this study, we developed a delivery system based on pullulan microbeads (PMBs) for sequential release of the chemokine CCL-5 to recruit these disc stem/progenitor cells to the NP tissue, followed by the release of the growth factors TGF-β1 and GDF-5 to induce the synthesis of a collagen type II-and aggrecan-rich extracellular matrix (ECM). Bioactivity of released CCL5 on human adipose-derived stem cells (hASCs), selected to mimic disc stem/progenitors, was demonstrated using a Transwell® chemotaxis assay. The regenerative effects of loaded PMBs were investigated in ex vivo spontaneously degenerated ovine IVDs. Fluorescent hASCs were seeded on the top cartilaginous endplates (CEPs); the degenerated NPs were injected with PMBs loaded with CCL5, TGF-β1, and GDF-5; and the IVDs were then cultured for 3, 7, and 28 days to allow for cell migration and disc regeneration. The PMBs exhibited sustained release of biological factors for 21 days. Ex vivo migration of seeded hASCs from the CEP toward the NP was demonstrated, with the cells migrating a significantly greater distance when loaded PMBs were injected (5.8 ± 1.3 mm vs. 3.5 ± 1.8 mm with no injection of PMBs). In ovine IVDs, the overall NP cellularity, the collagen type II and the aggrecan staining intensities, and the Tie2+ progenitor cell density in the NP were increased at day 28 compared to the control groups. Considered together, PMBs loaded with CCL5/TGF-β1/GDF-5 constitute an innovative and promising strategy for controlled release of growth factors to promote cell recruitment and extracellular matrix remodelling.

TPA induces damage to the endplates, and it may lead to neurological impairment and leakage of injected materials into the systemic circulation. These adverse effects must be fully considered before proceeding with TPA for IVD regenerative strategies.

The founder cells of the Nucleus pulposus, the centre of the intervertebral disc, originate in the embryonic notochord. After birth, mature notochordal cells (NC) are identified as key regulators of disc homeostasis. Better understanding of their biology has great potential in delaying the onset of disc degeneration or as a regenerative-cell source for disc repair. Using human pluripotent stem cells, we developed a two-step method to generate a stable NC-like population with a distinct molecular signature. Time-course analysis of lineage-specific markers shows that WNT pathway activation and transfection of the notochord-related transcription factor NOTO are sufficient to induce high levels of mesendoderm progenitors and favour their commitment toward the notochordal lineage instead of paraxial and lateral mesodermal or endodermal lineages. This study results in the identification of NOTO-regulated genes including some that are found expressed in human healthy disc tissue and highlights NOTO function in coordinating the gene network to human notochord differentiation.

In situ forming hydrogels that can be injected into tissues in a minimally-invasive fashion are appealing as delivery vehicles for tissue engineering applications. Ideally, these hydrogels should have mechanical properties matching those of the host tissue, and a rate of degradation adapted for neo-tissue formation. Here, the development of in situ forming hyaluronic acid hydrogels based on the pH-triggered condensation of silicon alkoxide precursors into siloxanes is reported. Upon solubilization and pH adjustment, the low-viscosity precursor solutions are easily injectable through fine-gauge needles prior to in situ gelation. Tunable mechanical properties (stiffness from 1 to 40 kPa) and associated tunable degradability (from 4 days to more than 3 weeks in vivo) are obtained by varying the degree of silanization (from 4.3% to 57.7%) and molecular weight (120 and 267 kDa) of the hyaluronic acid component. Following cell encapsulation, high cell viability (> 80%) is obtained for at least 7 days. Finally, the in vivo biocompatibility of silanized hyaluronic acid gels is verified in a subcutaneous mouse model and a relationship between the inflammatory response and the crosslink density is observed. Silanized hyaluronic acid hydrogels constitute a tunable hydrogel platform for material-assisted cell therapies and tissue engineering applications.

Polysaccharides have received a lot of attention in biomedical research for their high potential as scaffolds owing to their unique biological properties. Fibrillar scaffolds made of chitosan demonstrated high promise in tissue engineering, especially for skin. As far as bone regeneration is concerned, curdlan (1,3-β-glucan) is particularly interesting as it enhances bone growth by helping mesenchymal stem cell adhesion, by favoring their differentiation into osteoblasts and by limiting the osteoclastic activity. Therefore, we aim to combine both chitosan and curdlan polysaccharides in a new scaffold for bone regeneration. For that purpose, curdlan was electrospun as a blend with chitosan into a fibrillar scaffold. We show that this novel scaffold is biodegradable (8% at two weeks), exhibits a good swelling behavior (350%) and is non-cytotoxic in vitro. In addition, the benefit of incorporating curdlan in the scaffold was demonstrated in a scratch assay that evidences the ability of curdlan to express its immunomodulatory properties by enhancing cell migration. Thus, these innovative electrospun curdlan–chitosan scaffolds show great potential for bone tissue engineering.

Dynamic hydrogels are viscoelastic materials that can be designed to be self-healing, malleable, and injectable, making them particularly interesting for a variety of biomedical applications. For the design of dynamic...

Articular cartilage (AC) may be affected by many injuries including traumatic lesions that predispose to osteoarthritis. Currently there is no efficient cure for cartilage lesions. In that respect, new strategies for regenerating AC are contemplated with interest. In this context, we aim to develop and characterize an injectable, self-hardening, mechanically reinforced hydrogel (Si-HPCH) composed of silanised hydroxypropymethyl cellulose (Si-HPMC) mixed with silanised chitosan. The in vitro cytocompatibility of Si-HPCH was tested using human adipose stromal cells (hASC). In vivo, we first mixed Si-HPCH with hASC to observe cell viability after implantation in nude mice subcutis. Si-HPCH associated or not with canine ASC (cASC), was then tested for the repair of osteochondral defects in canine femoral condyles. Our data demonstrated that Si-HPCH supports hASC viability in culture. Moreover, Si-HPCH allows the transplantation of hASC in the subcutis of nude mice while maintaining their viability and secretory activity. In the canine osteochondral defect model, while the empty defects were only partially filled with a fibrous tissue, defects filled with Si-HPCH with or without cASC, revealed a significant osteochondral regeneration. To conclude, Si-HPCH is an injectable, self-setting and cytocompatible hydrogel able to support the in vitro and in vivo viability and activity of hASC as well as the regeneration of osteochondral defects in dogs when implanted alone or with ASC.