Stem cell therapy for damaged cartilage suffers from low rates of retention, survival, and differentiation into chondrocytes at the target site. To solve these problems, here we propose a two-dimensional/three-dimensional (2D/3D) nanocomposite system. As a new two-dimensional (2D) material, hexagonal layered double hydroxides (LDHs) with a uniform lateral length of 2-3 μm were prepared by a hydrothermal process. Then, tonsil-derived mesenchymal stem cells (TMSCs), arginylglycylaspartic acid-coated LDHs, and kartogenin (KGN) were incorporated into the gel through the thermal-energy-driven gelation of the system. The cells exhibited a tendency to aggregate in the nanocomposite system. In particular, chondrogenic biomarkers of type II collagen and transcription factor SOX 9 significantly increased at both the mRNA and protein levels in the nanocomposite system, compared to the pure thermogel systems. The inorganic 2D materials increased the rigidity of the matrix, slowed down the release of a soluble factor (KGN), and improved cell-material interactions in the gel. The current 2D/3D nanocomposite system of bioactive LDH/thermogel can be a new platform material overcoming drawbacks of hydrogel-based 3D cell culture systems and is eventually expected to be applied as an injectable stem cell therapy.

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Background: Accurate identification of tumor sites and boundaries is of paramount importance during minimally invasive surgery. Although laparoscopic resection is being increasingly and widely performed for early gastric and colorectal cancers, the detection of tumors located inside the stomach and intestine is difficult owing to the lack of tactile sensation. Here, we propose the application of an indocyanine green (ICG)-loaded alginate hydrogel system as a fluorescence surgical marker for precise laparoscopic operations.Methods: A physical complex of ICG and human serum albumin (HSA) was mixed with sodium alginate to form an injectable hydrogel system. Calcium carbonate and D-gluconic acid (GA) were added to the gel to control its strength and gelation time, respectively. The optimal conditions for the preparation of injectable hydrogels were determined by analyzing the fluorescence spectra and sol-gel transition time of the prepared samples at various concentrations and compositions. Next, the aqueous solutions of ICG, ICG-HSA, and ICG-HSA-loaded alginate were subcutaneously injected into nude mice (three mice per group), and nearinfrared (NIR) fluorescence images of the mice (λ ex. =780 nm, λ em. =845 nm) were obtained at different points in time for 8 days. Then, fluorescence intensities at the injection sites, target-to-background ratio, and areas of ICG fluorescence were analyzed. Finally, the potential utility of ICG-HSA-loaded alginate hydrogel as a surgical marker was evaluated in a porcine model. The ICG-HSA-loaded alginate solution was injected into three sites in the submucosal space of the porcine stomach via a catheter. A fluorescent laparoscopic system was installed on the abdomen of the pig 3 days post-injection, and the fluorescence signal generated from the fluorescence surgical marker located inside the stomach was evaluated using the fluorescence laparoscope system (λ ex. =785 nm, λ em. =805 nm). Results:The optimal concentration of ICG-HSA complex was determined to be 30 μM, and maximum fluorescence intensity of the complex was obtained at a 1:1 mole ratio of HSA to ICG. The subcutaneous injection of ICG or ICG-HSA solution in mice resulted in the rapid spread of the fluorescence signal around the injection site in 3 h, and a weak fluorescence was detected at the injection site 24 h post-injection. In contrast, the fluorescence detection time was effectively prolonged up to 96 h post-injection in the case of ICG-HSA-loaded alginate gel, while diffusion of the injected ICG from the injection site was effectively prevented. In the laparoscopic operation, injection sites of the hydrogel in porcine stomach could be accurately detected in real time even after 3 days.Conclusions: This alginate hydrogel system may be potentially useful as an effective surgical marker in terms of accuracy and persistence for laparoscopic operation.

Yolk proteins (YPl, YP2, and YP3) of the fall webworm, Hyphantria cunea, are of relatively low molecular weight. Yolk protein-2 (YP2) was purified from gel slices and by KBr density gradient ultracentrifugation followed by ion exchange chromatography. YP2 i s composed of one subunit with a molecular weight of 35.5 kDa. YP2 contains neutral lipids (diacylglycerol and triacylglycerol) and phospholipids (phosphatidylcholine and phosphatidylethanolamine). The neutral lipids are largely composed of lauric acid and palrnitoleic acid. YP2 contains relatively large amounts of glutamic acid and aspartic acid but small amounts of tyrosine, phenylalanine, and methionine. YP2 is a vitellin (Vn) synthesized by the fat body. Vitellogenin-2 (Vg2), the precursor of YP2, is present in very small amounts in the hemolymph. Lipophorin and storage protein also are found in the ovary of H. cunea, and these proteins do not immunologically cross-react with YP2. YP2 is detected in first instar larvae but completely disappears during the second instar, indicating that YP2 is intensively utilized during postembryonic development. Anti-YP2 antibodies cross-react with ovarial extracts of Bornbyx mori but not with those of insects from other orders such as Cletus schrnidti (Hemiptera), Lucilia illustris (Diptera), Anechura japonica (Dermaptera), Periplaneta americana (Dictyoptera), and Ducetia japonica (Orthoptera). o 1995 WiIey-Liss, Inc.