Shear-thinning, self-healing hydrogels are promising vehicles for therapeutic cargo delivery due to their ability to be injected using minimally invasive surgical procedures. An injectable hydrogel using a novel combination of dynamic covalent crosslinking with thermoresponsive engineered proteins is presented. Ex situ at room temperature, rapid gelation occurs through dynamic covalent hydrazone bonds by simply mixing two components: hydrazine-modified elastin-like protein (ELP) and aldehyde-modified hyaluronic acid. This hydrogel provides significant mechanical protection to encapsulated human mesenchymal stem cells during syringe needle injection and rapidly recovers after injection to retain the cells homogeneously within a 3D environment. In situ, the ELP undergoes a thermal phase transition, as confirmed by coherent anti-Stokes Raman scattering microscopy observation of dense ELP thermal aggregates. The formation of the secondary network reinforces the hydrogel and results in a tenfold slower erosion rate compared to a control hydrogel without secondary thermal crosslinking. This improved structural integrity enables cell culture for three weeks postinjection, and encapsulated cells maintain their ability to differentiate into multiple lineages, including chondrogenic, adipogenic, and osteogenic cell types. Together, these data demonstrate the promising potential of ELP-HA hydrogels for injectable stem cell transplantation and tissue regeneration. for generously sharing the uronic acid assay protocol. The authors acknowledge Brad Krajina for assistance in characterization of polymer molecular weight.

Stem cell transplantation via direct injection is a minimally invasive strategy being explored for treatment of a variety of injuries and diseases. Injectable hydrogels with shear moduli <50 Pa can mechanically protect cells during the injection process; however, these weak gels typically biodegrade within 1–2 weeks, which may be too fast for many therapeutic applications. To address this limitation, an injectable hydrogel is designed that undergoes two different physical crosslinking mechanisms. The first crosslinking step occurs ex vivo through peptide‐based molecular recognition to encapsulate cells within a weak gel that provides mechanical protection from injection forces. The second crosslinking step occurs in situ to form a reinforcing network that significantly retards material biodegradation and prolongs cell retention time. Human adipose‐derived stem cells are transplanted into the subcutaneous space of a murine model using hand‐injection through a 28‐gauge syringe needle. Cells delivered within the double‐network hydrogel are significantly protected from mechanical damage and have significantly enhanced in vivo cell retention rates compared to delivery within saline and single network hydrogels. These results demonstrate that in situ formation of a reinforcing network within an already existing hydrogel can greatly improve transplanted cell retention, thereby enhancing potential regenerative medicine therapies.

BR/LA PDAC patients with no progression on neoadjuvant FOLFIRINOX should be offered surgical exploration. Except size, traditional pathological parameters fail to predict survival among resected FOLFIRINOX patients. Resected FOLFIRINOX patients have survival that appears to be superior than that of resectable patients who go directly to surgery.

Purpose More effective therapy is needed for intrahepatic cholangiocarcinoma (ICC). The encouraging clinical results obtained with checkpoint molecule-specific monoclonal antibodies (mAb) have prompted us to investigate whether this type of immunotherapy may be applicable to ICC. The aims of this study were to determine whether (i) patients mount a T-cell immune response to their ICC, (ii) checkpoint molecules are expressed on both T cells and tumor cells, and (iii) tumor cells are susceptible to recognition by cognate T cells. Experimental Design Twenty-seven ICC tumors were analyzed for (i) lymphocyte infiltrate, (ii) HLA class I and HLA class II expression, and (iii) PD-1 and PD-L1 expression by T cells and ICC cells, respectively. The results of this analysis were correlated with the clinicopathologic characteristics of the patients investigated. Results Lymphocyte infiltrates were identified in all tumors. PD-L1 expression and HLA class I antigen expression by ICC cells was observed in 8 and 11, respectively, of the 27 tumors analyzed. HLA class I antigen expression correlated with CD8+ T-cell infiltrate. Furthermore, positive HLA class I antigen expression in combination with negative/rare PD-L1 expression was associated with favorable clinical course of the disease. Conclusions ICC patients are likely to mount a T-cell immune response against their own tumors. Defects in HLA class I antigen expression in combination with PD-L1 expression by ICC cells provide them with an immune escape mechanism. This mechanism justifies the implementation of immunotherapy with checkpoint molecule-specific mAbs in patients bearing ICC tumors without defects in HLA class I antigen expression.

Septic shock results from an uncontrolled inflammatory response, mediated primarily by LPS. Cholesterol transport plays an important role in the host response to LPS, as LPS is neutralized by lipoproteins and adrenal cholesterol uptake is required for antiinflammatory glucocorticoid synthesis. In this study, we show that scavenger receptor B-I (SR-BI), an HDL receptor that mediates HDL cholesterol ester uptake into cells, is required for the normal antiinflammatory response to LPS-induced endotoxic shock. Despite elevated plasma HDL levels, SR-BI-null mice displayed an uncontrollable inflammatory cytokine response and a markedly higher lethality rate than control mice in response to LPS. In addition, SR-BI-null mice showed a lack of inducible glucocorticoid synthesis in response to LPS, bacterial infection, stress, or ACTH. Glucocorticoid insufficiency in SR-BI-null mice was due to primary adrenal malfunction resulting from deficient cholesterol delivery from HDL. Furthermore, corticosterone supplementation decreased the sensitivity of SR-BI-null mice to LPS. Plasma from control and SR-BI-null mice exhibited a similar ability to neutralize LPS, whereas SR-BI-null mice showed decreased plasma clearance of LPS into the liver and hepatocytes compared with normal mice. We conclude that SR-BI in mice is required for the antiinflammatory response to LPS-induced endotoxic shock, likely through its essential role in facilitating glucocorticoid production and LPS hepatic clearance.

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Serum amyloid A is an acute phase protein that is carried in the plasma largely as an apolipoprotein of high density lipoprotein (HDL). In this study we investigated whether SAA is a ligand for the HDL receptor, scavenger receptor class B type I (SR-BI), and how SAA may influence SR-BI-mediated HDL binding and selective cholesteryl ester uptake. Studies using Chinese hamster ovary cells expressing SR-BI showed that 125 Ilabeled SAA, both in lipid-free form and in reconstituted HDL particles, functions as a high affinity ligand for SR-BI. SAA also bound with high affinity to the hepatocyte cell line, HepG2. Alexa-labeled SAA was shown by fluorescence confocal microscopy to be internalized by cells in a SR-BI-dependent manner. To assess how SAA association with HDL influences HDL interaction with SR-BI, SAA-containing HDL was isolated from mice overexpressing SAA through adenoviral gene transfer. SAA presence on HDL had little effect on HDL binding to SR-BI but decreased (30 -50%) selective cholesteryl ester uptake. Lipid-free SAA, unlike lipid-free apoA-I, was an effective inhibitor of both SR-BI-dependent binding and selective cholesteryl ester uptake of HDL. We have concluded that SR-BI plays a key role in SAA metabolism through its ability to interact with and internalize SAA and, further, that SAA influences HDL cholesterol metabolism through its inhibitory effects on SR-BI-mediated selective lipid uptake.