Point-of-care non-invasive enzyme-cleavable nanosensors for acute transplant rejection detection.

Accurate and non-invasive monitoring of allograft posttransplant is essential for early detection of acute cellular rejection and determines the long-term survival of the graft. Clinically, tissue biopsy is the most effective approach for diagnosing transplant rejection. Nonetheless, the procedure is invasive and potentially triggers organ failure. This work aims to design and apply GzmB-responsive nanosensors (GBRNs) that can readily size-change in graft tissues. Subsequently, we investigate the activity of serine protease granzyme B by generating a direct colorimetric urinary readout for non-invasive detection of transplant rejection in under 1 h. In preclinical heart graft mice models of transplant rejection, GBRNs were cleaved by GzmB and excreted by the kidneys via accurate nanometre-size glomerular filtration. By exploiting the catalytic activity of ultrasmall gold nanoclusters, GBRNs urinalysis promotes ultrasensitive surveillance of rejection episodes with a receiver operator characteristic curve area under the curve of 0.896 as well as a 95% confidence interval of about 0.7701-1.000. Besides, the catalytic activity of gold nanoclusters in urine can be detected at point-of-care testing to predict the immunity responses in mice with insufficient immunosuppressive therapy. Therefore, this non-invasive, sensitive, and quantitative method is a robust and informative approach for rapid and routine monitoring of transplant allografts without invasive biopsy.

Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Ameliorate HaCaT Cell Photo-Aging.

Umbilical cord mesenchymal stem cells (UCMSCs) have been identified as a potentially ideal cell type for use in regenerative therapeutic contexts owing to their excellent paracrine secretory abilities and other desirable properties. Previous work has shown that stem cell-derived exosomes can effectively reduce skin aging, but few studies have specifically focused on the role of UCMSC-derived exosomes in this context. In this study, we isolated exosomes derived from UCMSCs grown in a three-dimensional culture system and explored their ability to modulate the photo-aging of HaCaT keratinocytes. Cell viability and proliferation were assessed using CCK8 assay, whereas wound healing and transwell assays were used to assess cell migratory capabilities. UVB irradiation (60 mJ/cm2) was used to induce photo-aging of HaCaT cells. TUNEL and SA-ß-Gal staining were used to explore HaCaT cell apoptosis and senescence, respectively, whereas real-time quantitative PCR was used to assess the expression of relevant genes at the mRNA level. We found that UCMSC-derived exosomes were able to enhance normal HaCaT cell proliferation and migration while also inhibiting UVB-induced damage to these cells. These exosomes also reduced HaCaT cell apoptosis and senescence, increasing collagen type I expression and reducing matrix metalloproteinase (MMP1) expression in photo-aged HaCaT cells. Together, these findings indicate that UCMSC-derived exosomes have the potential to be used therapeutically to suppress skin aging.

Effect of various pretreatments on improving cellulose enzymatic digestibility of tobacco stalk and the structural features of co-produced hemicelluloses.

Hereon, tobacco stalk was deconstructed by lyophilization, ball-milling, ultrasound-assisted alkali extraction, hydrothermal pretreatment (HTP), and alkali presoaking, respectively, followed by dilute alkali cooking to both improve its enzymatic digestibility and isolate the hemicellulosic streams. It was found that a maximum cellulose saccharification rate of 93.5% was achieved from the integrated substrate by ball-milling and dilute alkali cooking, which was 4.4-fold higher than that from the raw material. Interestingly, in this case, 76.9% of hemicelluloses were simultaneously recovered during the integrated treatment. Structural determination indicated that the hemicelluloses released from tobacco stalk by dilute alkali cooking were mixed polysaccharides, and the (1 â†’ 4)-linked ß-D-Xylp backbone branched with L-Araf units at O-2/O-3 and 4-O-Me-α-D-GlcpA units at O-2 of the xylose residues was the main structure. In comparison, ultrasound-assisted alkali extraction, ball-milling, and HTP favored the extraction of hemicelluloses with less branched structure and lower molecular weights in the following alkali cooking.

Peroneus Longus Tendon Autograft is a Safe and Effective Alternative for Anterior Cruciate Ligament Reconstruction.

The ipsilateral peroneus longus tendon (PLT) was utilized as an autograft for anterior cruciate ligament (ACL) reconstruction of patients with acute ACL rupture and grade III medial collateral ligament (MCL) injury. We investigated the efficacy and safety of this alternative autograft compared with autologous hamstring tendon (HT). Biomechanical testing of the graft options was performed and compared with the native ACL. Thirty-eight patients with acute ACL ruptures and grade III MCL injuries were treated with ACL reconstruction with a doubled autologous PLT or quadrupled autologous HT. Knee stability and function was evaluated clinically with the Lachman test and KT-2000 arthometer as well as subjectively with functional scores. Effects on the donor ankle were evaluated by biomechanical testing. The ultimate tensile strengths of doubled PLT and quadrupled HT were significantly higher than that of the native ACL and the ultimate tensile strength of doubled PLT was comparable with that of quadrupled HT. There were no significant differences in clinical or functional scores between the two groups. There were no significant differences in pre- and postoperative biomechanical testing of the donor ankle. PLT is a suitable alternative autograft for an ACL reconstruction in patients with a concomitant grade III MCL injury without a significant biomechanical disadvantage to the ankle donor site.

Effective tracking of bone mesenchymal stem cells in vivo by magnetic resonance imaging using melanin-based gadolinium3+ nanoparticles.

Tracking transplanted stem cells is necessary to clarify cellular properties and improve transplantation success. In this study, we designed and synthesized melanin-based gadolinium3+ (Gd3+ )-chelate nanoparticles (MNP-Gd3+ ) of ∼7 nm for stem cell tracking in vivo. MNP-Gd3+ possesses many beneficial properties, such as its high stability and sensitivity, shorter T1 relaxation time, higher cell labeling efficiency, and lower cytotoxicity compared with commercial imaging agents. We found that the T1 relaxivity (r1 ) of MNP-Gd3+ was significantly higher than that of Gd-DTPA; the nanoparticles were taken up by bone mesenchymal stem cells (BMSCs) via endocytosis and were broadly distributed in the cytoplasm. Based on an in vitro MTT assay, no cytotoxicity of labeled stem cells was observed for MNP-Gd3+ concentrations of less than 800 µg/mL. Furthermore, we tracked MNP-Gd3+ -labeled BMSCs in vivo using 3.0T MRI equipment. After intramuscular injection, MNP-Gd3+ -labeled BMSCs were detected, even after four weeks, by 3T MRI. We concluded that MNP-Gd3+ nanoparticles at appropriate concentrations can be used to effectively monitor and track BMSCs in vivo. MNP-Gd3+ nanoparticles have potential as a new positive MRI contrast agent in clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 131-137, 2017.

An adaptive biointerface from self-assembled functional peptides for tissue engineering.

A self-assembled peptide-based biointerface is demonstrated with triple functional layers that can significantly improve the tissue self-healing process or prevent biofilm-mediated chronic inflammation. This smart biointerface is composed of three functional moieties (i.e., a cell-adhesive peptide, an infectious environment-responsive peptide, and an antifouling hexaethylene glycol (HEG) layer), and the resulting interface coated onto prosthetic replacements can smartly respond to the surrounding physiological or pathological microenvironment.

[Study on effect of psoralidin on anti-experimental postmenopausal osteoporosis and its mechanism].

OBJECTIVE: To observe the effect of psoralidine in rats with ovariectomy, and preliminarily study its mechanism. METHOD: Sixty female Sprague-Dawley rats were divided into 5 groups: the sham operation group, the model group, the psoralidine low-dose group (4 mg x kg(-1)), the psoralidine high-dose group (16 mg x kg(-1)) and the Zhuangguzhitong capsule group, with 12 rats in each group. Thirteen weeks later, their blood and bone samples were collected to detect bone density, bone biochemistry, pathomorphology, serum E2 and CT. RESULT: Psoralidine could up-regulate the bone density of lumbar vertebra and thighbone of rats with ovariectomy (P < 0.05), the maximum bending strength of thighbone (P < 0.05), and serum E2 and CT (P < 0.05). CONCLUSION: Psoralidine has a good active effect on postmenopausal antiosteoporosis. Its mechanism may be related to such pathways as E2 and CT.

Tau overexpression inhibits cell apoptosis with the mechanisms involving multiple viability-related factors.

The formation of neurofibrillary tangles, mainly composed of hyperphosphorylated tau protein, is a hallmark in the brain of human tauopathies, including Alzheimer's disease (AD). Although neurons bearing neurofibrillary tangles are constantly exposed to various apoptotic stimuli, they do not appear to preferentially die by apoptosis. The underlying mechanism for such resistance to apoptosis remains elusive. Previously, we studied the role of tau phosphorylation in apoptosis and found that tau hyperphosphorylation by glycogen synthase kinase-3 (GSK-3) rendered cells more resistant to apoptosis. In this study, we show that the overexpression of tau without any exogenous activation of kinases also confers increased resistance to apoptosis in both N2a cells and in a tau transgenic mouse model. Mechanistically, the overexpression of tau was associated with a reduced p53 level, decreased release of cytochrome C from mitochondria, and inhibition of caspases-9/-3. Additionally, a decreased phosphorylation and increased nuclear translocation of beta-catenin were also detected in N2a/tau cells, and knockdown of beta-catenin eliminated the anti-apoptotic effect of tau. Furthermore, tau was spontaneously hyperphosphorylated upon overexpression and by staurosporine treatment. The phosphorylation level of p53 decreased upon tau overexpression, and a more profound reduction of the phosphorylated p53 was detected when the cells were treated with lithium and roscovitine, inhibitors of GSK-3 and cyclin-dependent kinase-5 (Cdk-5). These results suggest that the overexpression of tau, which may be hyperphosphorylated by endogenous GSK-3 and Cdk-5, is anti-apoptotic by mechanisms involving modulation of multiple anti-apoptotic factors, including beta-catenin and p53-mitochondria-caspase-mediated apoptotic pathways.

Overactivated mitogen-activated protein kinase by anisomycin induces tau hyperphosphorylation.

One of the pathological feathers of Alzheimer's disease (AD) is neurofibrillary tangles (NFTs), which consist of paired helical filaments (PHFs) formed by hyperphosphorylated microtubule-associated protein tau. To study the role of mitogen-activated protein kinase (MAPK) in tau hyperphosphorylation and the underlying mechanism, wild type mouse neuroblastoma cells (N2a) were dealt with different concentrations (0.1 microg/mL, 0.2 microg/mL and 0.4 microg/mL) of anisomycin (an activator of MAPK) for 6 h. The relationship between MAPK activity and tau phosphorylation at some Alzheimer-sites was analyzed, and the activities of protein kinase A (PKA) and glycogen synthase kinase-3 (GSK-3) were detected. The results showed that anisomycin activated MAPK in a dose-dependent manner, but tau hyperphosphorylation at Ser-198/199/202 and Ser-396/404 sites was only observed when the concentration of anisomycin was at the level of 0.4 microg/mL, and the alteration of tau phosphorylation at Ser-214 showed no significant difference in different groups. 0.2 microg/mL and 0.4 microg/mL of anisomycin led to an increase in the activity of GSK-3, respectively, but had no effect on the activity of PKA. Lithium chloride, a specific inhibitor of GSK-3, completely abolished the anisomycin-induced elevation of tau phosphorylation without any effect on the activity of MAPK. In conclusion, overactivation of MAPK up to a certain degree induces tau hyperphosphorylation at Ser-198/199/202 and Ser-396/404 sites, and this is probably related to the effect of activated GSK-3 by MAPK.

Prolonged Alzheimer-like tau hyperphosphorylation induced by simultaneous inhibition of phosphoinositol-3 kinase and protein kinase C in N2a cells.

Co-injection of wortmannin (inhibitor of phosphatidylinositol-3 kinase, PI3K) and GF109203X (inhibitor of protein kinase C, PKC) into the rat brain was found to induce spatial memory deficiency and enhance tau hyperphosphorylation in the hippocampus of rat brain. To establish a cell model with durative Alzheimer-like tau hyperphosphorylation in this study, we treated N2a neuroblastoma cells with wortmannin and GF109203X separately and simultaneously, and measured the glycogen synthase kinase 3 (GSK-3) activity by gamma-32P-labeling and the level of tau phosphorylation by Western blotting. It was found that the application of wortmannin alone only transitorily increased the activity of GSK-3 (about 1 h) and the level of tau hyperphosphorylation at Ser396/Ser404 and Ser199/Ser202 sites (no longer than 3 h); however, a prolonged and intense activation of GSK-3 (over 12 h) and enhanced tau hyperphosphorylation (about 24 h) were observed when these two selective kinase inhibitors were applied together. We conclude that the simultaneous inhibition of PI3K and PKC can induce GSK-3 overactivation, and further strengthen and prolong the Alzheimer-like tau hyperphosphorylation in N2a cells, suggesting the establishment of a cell model with early pathological events of Alzheimer's disease.

Tau becomes a more favorable substrate for GSK-3 when it is prephosphorylated by PKA in rat brain.

Microtubule-associated protein tau is abnormally hyperphosphorylated in Alzheimer's disease (AD) and other tauopathies and is believed to lead to neurodegeneration in this family of diseases. Here we show that infusion of forskolin, a specific cAMP-dependent protein kinase A (PKA) activator, into the lateral ventricle of brain in adult rats induced activation of PKA by severalfold and concurrently enhanced the phosphorylation of tau at Ser-214, Ser-198, Ser-199, and or Ser-202 (Tau-1 site) and Ser-396 and or Ser-404 (PHF-1 site), which are among the major abnormally hyperphosphorylated sites seen in AD. PKA activation positively correlated to the extent of tau phosphorylation at these sites. Infusion of forskolin together with PKA inhibitor or glycogen synthase kinase-3 (GSK-3) inhibitor revealed that the phosphorylation of tau at Ser-214 was catalyzed by PKA and that the phosphorylation at both the Tau-1 and the PHF-1 sites is induced by basal level of GSK-3, because forskolin activated PKA and not GSK-3 and inhibition of the latter inhibited the phosphorylation at Tau-1 and PHF-1 sites. Inhibition of cdc2, cdk5, or MAPK had no significant effect on the forskolin-induced hyperphosphorylation of tau. Forskolin inhibited spatial memory in a dose-dependent manner in the absence but not in the presence of R(p)-adenosine 3',5'-cyclic monophosphorothioate triethyl ammonium salt, a PKA inhibitor. These results demonstrate for the first time that phosphorylation of tau by PKA primes it for phosphorylation by GSK-3 at the Tau-1 and the PHF-1 sites and that an associated loss in spatial memory is inhibited by inhibition of the hyperphosphorylation of tau. These data provide a novel mechanism of the hyperphosphorylation of tau and identify both PKA and GSK-3 as promising therapeutic targets for AD and other tauopathies.

Melatonin ameliorated okadaic-acid induced Alzheimer-like lesions.

AIM: To explore the protective effects of melatonin (Mel) on the abnormal phosphorylation of neuronal cytoskeletal proteins. METHODS: We generated a neuroblastoma (SH-SY5Y) cell system in which cytoskeletal proteins are abnormally phosphorylated resulting in microtubule disruption due to the marked inhibition of protein phosphatase activities by okadaic acid (OA). RESULTS: OA-induced declines in cell viability and mitochondrial metabolic activity were remarkably prevented by Mel. In addition, the hyperphosphorylation/accumulation of neurofilament-(NF-) H/M subunits and the disruption of microtubules, induced by OA, were significantly inhibited by Mel. CONCLUSION: Our results suggest multiple protective functions of Mel against a series of pathological lesions known to culminate in AD, including abnormal phosphorylation of cytoskeletal proteins, microtubule disassembly and mitochondrion-initiated cell toxicity.