[Research progress of hydrogel combined with mesenchymal stem cells in the treatment of spinal cord injury].

Spinal cord injury (SCI) is a complex pathological process. Based on the encouraging results of preclinical experiments, some stem cell therapies have been translated into clinical practice. Mesenchymal stem cells (MSCs) have become one of the most important seed cells in the treatment of SCI due to their abundant sources, strong proliferation ability and low immunogenicity. However, the survival rate of MSCs transplanted to spinal cord injury is rather low, which hinders its further clinical application. In recent years, hydrogel materials have been widely used in tissue engineering because of their good biocompatibility and biodegradability. The treatment strategy of hydrogel combined with MSCs has made some progress in SCI repair. This review discusses the significance and the existing problems of MSCs in the repair of SCI. It also describes the research progress of hydrogel combined with MSCs in repairing SCI, and prospects its application in clinical research, aiming at providing reference and new ideas for future SCI treatment.

Inhibition of Notch1 signaling promotes neuronal differentiation and improves functional recovery in spinal cord injury through suppressing the activation of Ras homolog family member A.

Neural stem cells (NSCs) transplantation represents a promising strategy for the repair of injured neurons, since NSCs not only produce multiple neurotrophic growth factors but also differentiate into mature cells to replace damaged cells. Previous studies have shown that Notch signaling pathway had negative effects on neuronal differentiation; however, the precise mechanism remained inadequately understood. This research aimed to investigate whether inhibition of Notch1 signaling promotes neuronal differentiation and improves functional recovery in rat spinal cord injury through suppressing the activation of Ras homolog family member A (RhoA). QPCR, western blot, and immunofluorescence experiments were used to analyze Notch1 signaling pathways, RhoA, Ras homologous -associated coiled-coil containing protein kinase 1 (ROCK1), cleaved caspased-3, and neuronal/astrocytic differentiation markers. The expression of RhoA and ROCK1 was inhibited by lentivirus or specific biochemical inhibitors. In spinal cord injury (SCI), motor function was assessed by hind limbs movements and electrophysiology. Tissue repairing was measured by immunofluorescence, Nissl staining, Fluorogold, HE staining, QPCR, western blot, and magnetic resonance imaging (MRI) experiments. Our results demonstrate that inhibition of Notch1 in NSCs can promote the differentiation of NSCs to neurons. Knockdown of RhoA and inhibition of ROCK1 both can promote neuronal differentiation through inhibiting the activation of Notch1 signaling pathway in NSCs. In SCI, silencing RhoA enhanced neuronal differentiation and improved tissue repairing/functional recovery by inhibiting the activation of Notch1 signaling pathway. Since Notch1 inhibits neuronal differentiation through activating the RhoA/ROCK1 signaling pathway in NSCs, our data suggest that the Notch1/RhoA/ROCK1/Hes1/Hes5 signaling pathway may serve as a novel target for the treatment of SCI.

Enhancement of scutellarin oral delivery efficacy by vitamin B12-modified amphiphilic chitosan derivatives to treat type II diabetes induced-retinopathy.

BACKGROUND: Diabetic retinopathy is the most common complication in diabetic patients relates to high expression of VEGF and microaneurysms. Scutellarin (Scu) turned out to be effective against diabetes related vascular endothelial cell dysfunction. However, its clinical applications have been limited by its low bioavailability. In this study, we formulated and characterized a novel intestinal target nanoparticle carrier based on amphiphilic chitosan derivatives (Chit-DC-VB12) loaded with scutellarin to enhance its bioavailability and then evaluated its therapeutic effect in experimental diabetic retinopathy model. RESULTS: Chit-DC-VB12 nanoparticles showed low toxicity toward the human colon adenocarcinoma (Caco-2) cells and zebra fish within concentration of 250 µg/ml, owing to good biocompatibility of chitosan. The scutellarin-loaded Chit-DC-VB12 nanoparticles (Chit-DC-VB12-Scu) were then prepared by self-assembly in aqueous solution. Scanning electron microscopy and dynamic light scattering analysis indicated that the Chit-DC-VB12-Scu nanoparticles were spherical particles in the sizes ranging from 150 to 250 nm. The Chit-DC-VB12-Scu nanoparticles exhibited high permeation in Caco-2 cell, indicated it could be beneficial to be absorbed in humans. We also found that Chit-DC-VB12 nanoparticles had a high cellular uptake. Bioavailability studies were performed in Sprague-Dawley rats, which present the area under the curve of scutellarin of Chit-DC-VB12-Scu was two to threefolds greater than that of free scutellarin alone. Further to assess the therapeutic efficacy of diabetic retinopathy, we showed Chit-DC-VB12-Scu down-regulated central retinal artery resistivity index and the expression of angiogenesis proteins (VEGF, VEGFR2, and vWF) of retinas in type II diabetic rats. CONCLUSIONS: Chit-DC-VB12 nanoparticles loaded with scutellarin have better bioavailability and cellular uptake efficiency than Scu, while Chit-DC-VB12-Scu nanoparticles alleviated the structural disorder of intraretinal neovessels in the retina induced by diabetes, and it also inhibited the retinal neovascularization via down-regulated the expression of angiogenesis proteins. In conclusion, the Chit-DC-VB12 nanoparticles enhanced scutellarin oral delivery efficacy and exhibited potential as small intestinal target promising nano-carriers for treatment of type II diabetes induced-retinopathy.

Targeted Inhibition of Leucine-Rich Repeat and Immunoglobulin Domain-Containing Protein 1 in Transplanted Neural Stem Cells Promotes Neuronal Differentiation and Functional Recovery in Rats Subjected to Spinal Cord Injury.

OBJECTIVE: Leucine-rich repeat and immunoglobulin domain-containing protein (LINGO)-1 is expressed in neural stem cells, and its neutralization results in sustained neuronal immaturity. Thus, targeted inhibition of LINGO-1 via RNA interference may enhance transplanted neural stem cell survival and neuronal differentiation in vivo. Furthermore, LINGO-1 RNA interference in neural stem cells represents a potential therapeutic strategy for spinal cord injury. DESIGN: Department of Spine Surgery, First Affiliated Hospital of Sun Yat-sen University. SETTING: Translational Medicine Center Research Laboratory, First Affiliated Hospital of Sun Yat-sen University. SUBJECTS: Female Sprague-Dawley rats. INTERVENTIONS: The animals were divided into three groups that underwent laminectomy and complete spinal cord transection accompanied by transplantation of control-RNA interference-treated or LINGO-1-RNA interference-treated neural stem cells at the injured site in vivo. In vitro, neural stem cells were divided into four groups for the following treatments: control, control RNA interference lentivirus, LINGO-1 RNA interference lentivirus and LINGO-1 complementary DNA lentivirusand the Key Projects of the Natural Science Foundation of Guangdong Province (No. S2013020012818). MEASUREMENTS AND MAIN RESULTS: Neural stem cells in each treatment group were examined for cell survival and neuronal differentiation in vitro and in vivo via immunofluorescence and Western blot analysis. Axonal regeneration and tissue repair were assessed via retrograde tracing using Fluorogold, electron microscopy, hematoxylin-eosin staining and MRI. Rats were also examined for functional recovery based on the measurement of spinal cord-evoked potentials and the Basso-Beattie-Bresnahan score. LINGO-1-RNA interference-treated neural stem cell transplantation increased tissue repair and functional recovery of the injured spinal cord in rats. Similarly, LINGO-1 RNA interference increased neural stem cell survival and neuronal differentiation in vitro. The mechanism underlying the effect of LINGO-1 RNA interference on the injured rat spinal cord may be that the significant inhibition of LINGO-1 expression in neural stem cells inactivated the RhoA and Notch signaling pathways, which act downstream of LINGO-1. CONCLUSIONS: Our findings indicate that transplantation of LINGO-1-RNA interference-treated neural stem cells facilitates functional recovery after spinal cord injury and represents a promising potential strategy for the repair of spinal cord injury.

Bone marrow mesenchymal stem cells protect alveolar macrophages from lipopolysaccharide-induced apoptosis partially by inhibiting the Wnt/ß-catenin pathway.

Apoptosis of alveolar macrophages (AMs) plays a pathogenic role in acute lung injury (ALI) and its severe type, acute respiratory distress syndrome (ARDS). Mesenchymal stem cells (MSCs) are promising therapeutic cells for preventing apoptosis and eliminating cellular injury. We investigated the effects of rat bone marrow mesenchymal stem cells (BMSCs) on lipopolysaccharide (LPS)-induced apoptosis in AMs using transwell experiments, and examined the underlying mechanisms LPS induced AMs apoptosis in a dose- and time-dependent fashion, whereas BMSCs reduced AMs apoptosis when co-cultured at appropriate ratios. BMSCs decreased expression of cleaved caspase-3 and the pro-apoptotic protein, Bax, whilst increased levels of the anti-apoptotic protein, Bcl-2, prolonging the lifespan of AMs in vitro. Promotion of AMs survival by BMSCs required down-regulation of p-GSK-3ß and ß-catenin in AMs. The anti-apoptosis action of BMSCs was reversed by SB216763, a specific inhibitor of GSK-3ß that also activates Wnt/ß-catenin signaling. In conclusion, BMSCs can attenuate AM apoptosis partially by suppressing the Wnt/ß-catenin pathway.

Inflammatory Factor IL1α Induces Aberrant Astrocyte Proliferation in Spinal Cord Injury Through the Grin2c/Ca2+/CaMK2b Pathway.

Spinal cord injury (SCI) is one of the most devastating traumas, and the aberrant proliferation of astrocytes usually causes neurological deficits. However, the mechanism underlying astrocyte over-proliferation after SCI is unclear. Grin2c (glutamate ionotropic receptor type 2c) plays an essential role in cell proliferation. Our bioinformatic analysis indicated that Grin2c and Ca2+ transport functions were inhibited in astrocytes after SCI. Suppression of Grin2c stimulated astrocyte proliferation by inhibiting the Ca2+/calmodulin-dependent protein kinase 2b (CaMK2b) pathway in vitro. By screening different inflammatory factors, interleukin 1α (IL1α) was further found to inhibit Grin2c/Ca2+/CaMK2b and enhance astrocyte proliferation in an oxidative damage model. Blockade of IL1α using neutralizing antibody resulted in increased Grin2c expression and the inhibition of astrocyte proliferation post-SCI. Overall, this study suggests that IL1α promotes astrocyte proliferation by suppressing the Grin2c/Ca2+/CaMK2b pathway after SCI, revealing a novel pathological mechanism of astrocyte proliferation, and may provide potential targets for SCI repair.

High expression of P-selectin induces neutrophil extracellular traps via the PSGL-1/Syk/Ca2+/PAD4 pathway to exacerbate acute pancreatitis.

Background: Excessive neutrophil extracellular traps (NETs) is involved in the progression of acute pancreatitis (AP) but the mechanisms controlling NETs formation in AP are not fully understood. Therefore, our study sought to investigate the mechanism of the highly expressed P-selectin stimulating the formation of NETs in AP. Methods: NETs formation was detected by flow cytometry, immunofluorescence staining, and cf-DNA and MPO-DNA complexes were measured as biomarkers of NETs formation. Neutrophils treated with P-selectin and pharmacological inhibitors were examined by western blot, immunofluorescence staining and flow cytometry. Mouse model of AP was established by caerulein and the effect of inhibiting P-selectin by PSI-697 on the level of NETs and PAD4 in pancreatic tissue was observed. The severity of AP was evaluated by histopathological score and the detection of serum amylase and lipase. Results: Patients with AP had elevated levels of NETs and P-selectin compared with healthy volunteers. Stimulation of P-selectin up-regulated the expression of PSGL-1, increased the phosphorylation of Syk, mediated intracellular calcium signal and led to the activation and expression of PAD4, which modulated NETs formation in neutrophils. Pretreament with PSI-697 blunted NETs formation and PAD4 expression in the pancreatic tissue, and ameliorated the severity of AP in mice. Conclusion: Taken together, these results suggest that P-selectin induces NETs through PSGL-1 and its downstream Syk/Ca2+/PAD4 signaling pathway, and that targeting this pathway might be a promising strategy for the treatment of AP.

Umbilical cord mesenchymal stem cells overexpressing CXCR7 facilitate treatment of ARDS-associated pulmonary fibrosis via inhibition of Notch/Jag1 mediated by the Wnt/ß-catenin pathway.

The therapeutic efficacy of umbilical cord mesenchymal stem cells (UCMSCs) in acute respiratory distress syndrome (ARDS) is mainly limited by the efficiency of homing of UCMSCs toward tissue damage. C-X-C chemokine receptor type 7 (CXCR7), which is involved in the mobilization of UCMSCs, is only expressed on the surface of a small proportion of UCMSCs. This study examined whether overexpression of CXCR7 in UCMSCs (UCMSCsOE-CXCR7) could improve their homing efficiency, and therefore, improve their effectiveness in fibrosis repair at the site of lung injury caused by ARDS. A lentiviral vector expressing CXCR7 was built and then transfect into UCMSCs. The impacts of CXCR7 expression of the proliferationand homing of UCMSCs were examined in a lipopolysaccharide-induced ARDS mouse model. The potential role and underlying mechanism of CXCR7 were examined by performing scratch assays, transwell assays, and immunoassays. The therapeutic dose and treatment time of UCMSCsOE-CXCR7 were directly proportional to their therapeutic effect on lung injury. In addition, overexpression of CXCR7 increased SDF-1-induced proliferation and migration of lung epithelial cells (Base-2b cells), and upregulation of CXCR7 inhibited α-SMA expression, suggesting that CXCR7 may have a role in alleviating pulmonary fibrosis caused by ARDS. Overexpression of CXCR7 in UCMSCs may improve their therapeutic effect of acute lung injury mouse, The mechanism of fibrosis repair by CXCR7 is inhibition of Jag1 via suppression of the Wnt/ß-catenin pathway under the chemotaxis of SDF-1.

Jagged1 contained in MSC-derived small extracellular vesicles promotes squamous differentiation of cervical cancer by activating NOTCH pathway.

PURPOSE: Cervical cancer is the fourth most common cancer in women and poses a major threat to women's health, urgently requiring new treatment methods. METHODS: This study first successfully extracted and identified small extracellular vesicles secreted by human umbilical cord-derived mesenchymal stem cells. We studied the effects of MSC-sEV on the squamous differentiation levels of cervical cancer CaSki cells in vitro, and explored the effects of MSC-sEV on the NOTCH pathway, the growth, proliferation, migration abilities and squamous differentiation levels of cervical cancer cells. The roles of MSC-sEV were also verified in human keratinocyte HaCaT cells. RESULTS: The results showed that Jagged1 protein on MSC-sEV can bind to NOTCH1 on cervical cancer cells, activate NOTCH signaling, and promote squamous differentiation levels in CaSki cells, thus inhibiting the growth, proliferation and migration abilities of CaSki cells. MSC-sEV can also activate the NOTCH pathway in HaCaT cells, but promote the viability of HaCaT cells. CONCLUSION: MSC-sEV can activate the NOTCH pathway to promote squamous differentiation of CaSki cells and inhibit the growth proliferation and migration abilities of CaSki cells which may be a new mechanism for cervical cancer treatment.

UCHL1 facilitates protein aggregates clearance to enhance neural stem cell activation in spinal cord injury.

Activation of endogenous neural stem cells (NSCs) is greatly significant for the adult neurogenesis; however, it is extremely limited in the spinal cord after injury. Recent evidence suggests that accumulation of protein aggregates impairs the ability of quiescent NSCs to activate. Ubiquitin c-terminal hydrolase l-1 (UCHL1), an important deubiquitinating enzyme, plays critical roles in protein aggregations clearance, but its effects on NSC activation remains unknown. Here, we show that UCHL1 promotes NSC activation by clearing protein aggregates through ubiquitin-proteasome approach. Upregulation of UCHL1 facilitated the proliferation of spinal cord NSCs after spinal cord injury (SCI). Based on protein microarray analysis of SCI cerebrospinal fluid, it is further revealed that C3+ neurotoxic reactive astrocytes negatively regulated UCHL1 and proteasome activity via C3/C3aR signaling, led to increased abundances of protein aggregations and decreased NSC proliferation. Furthermore, blockade of reactive astrocytes or C3/C3aR pathway enhanced NSC activation post-SCI by reserving UCHL1 and proteasome functions. Together, this study elucidated a mechanism regulating NSC activation in the adult spinal cord involving the UCHL1-proteasome approach, which may provide potential molecular targets and new insights for NSC fate regulation.

Human umbilical cord mesenchymal stem cells derived extracellular vesicles alleviate salpingitis by promoting M1-to-M2 transformation.

Background: With an increasing number of patients experiencing infertility due to chronic salpingitis after Chlamydia trachomatis (CT) infection, there is an unmet need for tissue repair or regeneration therapies. Treatment with human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hucMSC-EV) provides an attractive cell-free therapeutic approach. Methods: In this study, we investigated the alleviating effect of hucMSC-EV on tubal inflammatory infertility caused by CT using in vivo animal experiments. Furthermore, we examined the effect of hucMSC-EV on inducing macrophage polarization to explore the molecular mechanism. Results: Our results showed that tubal inflammatory infertility caused by Chlamydia infection was significantly alleviated in the hucMSC-EV treatment group compared with the control group. Further mechanistic experiments showed that the application of hucMSC-EV induced macrophage polarization from the M1 to the M2 type via the NF-κB signaling pathway, improved the local inflammatory microenvironment of fallopian tubes and inhibited tube inflammation. Conclusion: We conclude that this approach represents a promising cell-free avenue to ameliorate infertility due to chronic salpingitis.

PTH (1-34) enhances the therapeutic effect of bone marrow mesenchymal stem cell-derived exosomes by inhibiting proinflammatory cytokines expression on OA chondrocyte repair in vitro.

BACKGROUND: The effects of bone marrow mesenchymal stem cells (BMSCs) during the treatment of cartilage damage have been proven to be attributed to paracrine mechanisms, particularly the effect of exosomes. Exosomes from different batches are inhomogeneous, and different treatment effects are observed between samples. The purpose of this research was to find more effective and homogeneous exosomes for the repair of chondrocytes in osteoarthritis (OA). We observed the potential effects and possible mechanisms of exosomes derived from parathyroid hormone (PTH) (1-34)-preconditioned BMSCs (ExoPTH) in the alleviation of OA. MATERIALS AND METHODS: Exosomes derived from BMSCs (ExoBMSC) and ExoPTH were isolated by differential centrifugation. Primary rat chondrocytes were used to establish the OA model by interleukin 1 beta (IL-1ß) in vitro. The effects of these two types of exosomes on OA chondrocyte proliferation, migration, apoptosis, and extracellular matrix formation were measured and compared. We observed changes in IL-2, TNF-α, and IL-6 levels via Western blotting (WB), and quantitative real-time PCR (qRT-PCR). RESULTS: We successfully extracted ExoBMSC and ExoPTH and established an IL-1ß-induced OA model in primary chondrocytes from rats. Our study showed that IL-2, TNF-α, and IL-6 levels increased significantly in OA chondrocytes; however, both ExoBMSC and ExoPTH reduced the levels of IL-2, TNF-α, and IL-6. In addition, ExoPTH exhibited stronger anti-inflammatory effects. ExoPTH had a more marked effect on proliferation, migration, and production of the extracellular matrix (Col-II) in OA chondrocytes than ExoBMSC at 24 h. CONCLUSION: ExoPTH increased the migration, proliferation, and chondral matrix formation of OA chondrocytes in vitro. In OA chondrocyte therapy, the potential mechanism of ExoPTH might involve the inhibition of production of proinflammatory cytokines. Although the two types of exosomes had some similar effects, most effects of ExoPTH were better than those of ExoBMSC, so ExoPTH may have a better ability to alleviate OA.

Cell Infiltrative Inner Connected Porous Hydrogel Improves Neural Stem Cell Migration and Differentiation for Functional Repair of Spinal Cord Injury.

The disadvantages of cell-adaptive microenvironments and cellular diffusion out of the lesion have limited hydrogel-based scaffold transplantation treatment for neural connectivity, leading to permanent neurological disability from spinal cord injury. Herein, porous GelMA scaffold was prepared, in which the inner porous structure was optimized. The average pore size was 168 ± 71 µm with a porosity of 77.1%. The modulus of porous hydrogel was 593 ± 4 Pa compared to 1535 ± 85 Pa of bulk GelMA. The inner connected porous structure provided a cell-infiltrative matrix for neural stem cell migration and differentiation in vitro and eventually enhanced neuron differentiation and hindlimb strength and movement of animals in in vivo experiments. Furthermore, inflammation response and apoptosis were also alleviated after implantation. This work demonstrated that the porous hydrogel with appropriately connected micropores exhibit favorable cellular responses compared with traditional non-porous GelMA hydrogel. Taken together, our findings suggest that porous hydrogel is a promising scaffold for future delivery of stem cells and has prospects in material design for the treatment of spinal cord injury.

Nanoparticles composed of the tea polysaccharide-complexed cationic vitamin B12-conjugated glycogen derivative.

Tea polysaccharides exhibit multiple important bioactivities, but very few of them can be absorbed through the small intestine. To enhance the absorption efficacy of tea polysaccharides, a cationic vitamin B12-conjugated glycogen derivative bearing the diethylenetriamine residues (VB12-DETA-Gly) was synthesized and characterized using FTIR, 1H NMR, and UV-vis spectroscopy. An acidic tea polysaccharide (TPSA) was isolated from green tea. The TPSA/VB12-DETA-Gly complexed nanoparticles were prepared, which showed positive zeta potentials and were irregular spherical nanoparticles in the sizes of 50-100 nm. To enable the fluorescence and UV-vis absorption properties of TPSA, a Congo red residue-conjugated TPSA derivative (CR-TPSA) was synthesized. The interactions and complexation mechanism between the CR-TPSA and the VB12-DETA-Gly derivatives were investigated using fluorescence spectroscopy, resonance light scattering spectroscopy, and UV-vis spectroscopy. The results indicated that the electrostatic interaction could play a major role during the CR-TPSA and VB12-DETA-Gly-II complexation processes. The TPSA/VB12-DETA-Gly nanoparticles were nontoxic and exhibited targeted endocytosis for the Caco-2 cells, and showed high permeation through intestinal enterocytes using the Caco-2 cell model. Therefore, they exhibit potential for enhancing the absorption efficacy of tea polysaccharides through the small intestinal mucosa.

Cell-adaptable dynamic hydrogel reinforced with stem cells improves the functional repair of spinal cord injury by alleviating neuroinflammation.

Spinal cord injury (SCI) is one of the most challenging clinical issues. It is characterized by the disruption of neural circuitry and connectivity, resulting in neurological disability. Adipose-derived stem cells (ADSCs) serve as a promising source of therapeutic cells for SCI treatment. However, the therapeutic outcomes of direct ADSCs transplantation are limited in the presence of an inflammatory microenvironment. Herein, a cell-adaptable neurogenic (CaNeu) hydrogel was developed as a delivery vehicle for ADSCs to promote neuronal regeneration after SCI. The dynamic network of CaNeu hydrogel loaded with ADSCs provides a cell-infiltratable matrix that enhances axonal growth and eventually leads to improved motor evoked potential, hindlimb strength, and coordination of complete spinal cord transection in rats. Furthermore, the CaNeu hydrogel also establishes an anti-inflammatory microenvironment by inducing a shift in the polarization of the recruited macrophages toward the pro-regeneration (M2) phenotype. Our study showed that the CaNeu-hydrogel‒mediated ADSCs delivery resulted in significantly suppressed neuroinflammation and apoptosis, and that this phenomenon involved the PI3K/Akt signaling pathway. Our findings indicate that the CaNeu hydrogel is a valuable delivery vehicle to assist stem cell therapy for SCI, providing a promising strategy for central nervous system diseases.

P-Selectin-Based Dual-Model Nanoprobe Used for the Specific and Rapid Visualization of Early Detection toward Severe Acute Pancreatitis in Vivo.

Identifying severe acute pancreatitis (SAP) as soon as possible is critical for achieving optimal outcomes and saving lives. In this study, a novel P-selectin-targeted, NIR fluorescent dye (Cy 5.5)-labeled dual-modal nanoprobe based on diethylenetriaminepentaacetic chelates (Gd-DTPA-Cy5.5-PsLmAb) was constructed for the bimodal imaging of SAP at the early stage. Gd-DTPA-Cy5.5-PsLmAb was prepared, and its structure was characterized by Fourier transform infrared spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy, and its stability was evaluated. Biocompatibility was evaluated by the hemolysis and cytotoxicity assays. The enzyme-linked immunosorbent assay was used to detect and evaluate the expression of P-selectin in the peripheral blood of 11 patients with acute pancreatitis (AP) and 5 healthy volunteers. The bimodal imaging ability of Gd-DTPA-Cy5.5-PsLmAb nanoprobes was evaluated via near-infrared fluorescence (NIRF) and magnetic resonance imaging (MRI) in AP animal models in vivo. Gd-DTPA-Cy5.5-PsLmAb showed low toxicity to human embryonic kidney cells (293T cells) and good blood compatibility. The P-selectin levels of humans and rats in the mild acute pancreatitis (MAP)/SAP stage were significantly higher than those in the control group and reached the highest level at the SAP stage. Furthermore, Gd-DTPA-Cy5.5-PsLmAb nanoprobes showed clear NIRF imaging of mouse pancreas at the MAP stage and SAP stage by a fluorescence signal at 6.09 × 108 and 1.95 × 109, respectively. Meanwhile, Gd-DTPA-Cy5.5-PsLmAb nanoprobes also successfully showed the T1-weighted MR signal of rat pancreas at the MAP stage, but Gd-DTPA seldom showed any signal increase at the MAP stage; Gd-DTPA-Cy5.5-PsLmAb and Gd-DTPA could show an increasing MR signal of rat pancreas at the SAP stage. Gd-DTPA-Cy5.5-PsLmAb proved to offer a stronger signal than Gd-DTPA.Our findings indicate that Gd-DTPA-Cy5.5-PsLmAb is an effective and specific MR/NIRF dual nanoprobe for bimodal imaging, providing a promising diagnostic approach for early SAP in clinic.

RGD-Modified Nanocarrier-Mediated Targeted Delivery of HIF-1α-AA Plasmid DNA to Cerebrovascular Endothelial Cells for Ischemic Stroke Treatment.

Studies have shown that the use of proangiogenic genes can improve the prognosis of ischemic stroke by promoting angiogenesis at the injury site. For example, within this study, hypoxia-inducible factor 1-α (HIF-1α) has exhibited an angiogenic effect. Our previous study reported a more stable HIF-1α mutant form (HIF-1α-AA), which was transfected into mesenchymal stem cells to provide neuroprotective effects against ischemic stroke. The safety of nonviral gene vectors has attracted researchers' attention. This study encapsulated the HIF-1α-AA plasmid DNA into a newly synthesized effective nonviral gene vector, a hyperbranched cationic amylopectin derivative (DMAPA-Amyp) nanocarrier. In addition, a targeting strategy was applied to select the RGD peptides and bind to the designed nanocarrier as a molecule targeting endothelial cells. The targeting strategy is used to directly deliver the nanocarriers to the vascular endothelial cells of the brain peri-infarct site. This study emphasizes the targeting ability of nanocarrier and its therapeutic effect on cerebral ischemia. The results showed that RGD-DMAPA-Amyp had good biocompatibility and a high cell uptake rate, indicating that it is a safe nonviral gene vector that can be endocytosed by human cells. In rat models of ischemic stroke, compared with the nontargeted nanocarrier group, more RGD-DMAPA-Amyp nanoparticles aggregated in vascular endothelial cells of the peri-infarct region and significantly improved the recovery of neurological function. It is indicated that the RGD-modified nanomedicine promotes the recovery of nerve function more efficiently. Further study on the mechanism of RGD-DMAPA-Amyp/HIF-1α-AA in the treatment of cerebral ischemia displayed potential to significantly promote the formation of new blood vessels in vivo. Our findings suggest that the RGD-modified nonviral gene vector containing HIF-1α-AA appears to be a safe and promising therapeutic strategy for ischemic stroke gene therapy.

3D Printing Enabled Customization of Functional Microgels.

Injectable microgels show great promising applications in cell therapy and drug delivery. Currently, there remains a challenge to rapidly and cost-effectively fabricate customized microgels. Here, we present a digital light processing based three-dimensional (3D) printing process to fabricate microgels with tailored shapes and sizes. The microgels are constructed by the digital light controlled polymerization of photopolymerizable monomer solution within 2 s. By mixing nanoparticle-encapsulated drugs into the monomer solution, the microgels with sustained drug release can be readily prepared. Also, cells can be printed into microgels with survival and proliferation. In conclusion, this study provides a 3D printing process for customizing functional microgels containing drugs or cells with potential therapeutic applications.

Lentiviral vector delivery of short hairpin RNA to NgR1 promotes nerve regeneration and locomotor recovery in injured rat spinal cord.

Nogo receptor 1 (NgR1) is a high-affinity receptor of myelin-associated inhibitors (MAIs), and suppresses neurogenesis. Lentiviral vector are commonly used to alter the expression of targeted genes. However, little is known about the potential function of lentiviral vector harboring NgR1 shRNA (LV-NgR1 shRNA) on neurogenesis in spinal cord injury (SCI). In this study, the rats were randomly divided into three groups: including the LN (LV-NgR1 shRNA injection), LC (LV-control shRNA injection) and Sham (laminectomy only). Eight weeks post-injection of LV, spinal cords were examined by histology for changes in cavity size and by immunohistochemistry for changes in expression of NgR1, cell apoptosis, astrocytes, neurons and myelination. Motor function was assessed using the Basso, Beattie and Bresnahan (BBB) locomotor scale. Animals that received LV-NgR1 shRNA remarkably improved the motor function. These animals also showed an increase in levels of nerve fibers, synapses and myelination, a decrease in levels of lesion cavity and cell apoptosis at 8 weeks post-treatment. These findings give evidence that NgR1 may be a promising target for SCI treatment.

Preparation, complexation mechanism and properties of nano-complexes of Astragalus polysaccharide and amphiphilic chitosan derivatives.

To improve the small intestinal absorption efficacy of Astragalus polysaccharides (APS) through oral administration, amphiphilic chitosan derivatives conjugated with deoxycholic acid residues in the absence and presence of vitamin B12 residues (DA-Chit and VB12-DA-Chit, respectively) were synthesized and characterized by FTIR and NMR spectroscopy. APS and the amphiphilic chitosan derivatives formed the nano-complexes with positive zeta potentials in the size of 100-150nm observed using scanning electron microscopy. To investigate the fluorescent properties of APS, a Congo red residue-conjugated APS derivative (CR-APS) was synthesized. Fluorescence spectroscopy and resonance light scattering spectroscopy confirmed the formation of the CR-APS/DA-Chit nano-complex as a result of electrostatic interaction. The APS/DA-Chit and APS/VB12-DA-Chit nano-complexes were not toxic against the human colon adenocarcinoma (Caco-2) cells. The APS/VB12-DA-Chit nano-complex exhibited high permeation through intestinal enterocytes using the Caco-2 cell model, which could be beneficial to small intestinal absorption of humans.