IKVAV functionalized oriented PCL/Fe3O4 scaffolds for magnetically modulating DRG growth behavior.

The re-bridging of the deficient nerve is the main problem to be solved after the functional impairment of the peripheral nerve. In this study, a directionally aligned polycaprolactone/triiron tetraoxide (PCL/Fe3O4) fiber scaffolds were firstly prepared by electrospinning technique, and further then grafted with IKVAV peptide for regulating DRG growth and axon extension in peripheral nerve regeneration. The results showed that oriented aligned magnetic PCL/Fe3O4 composite scaffolds were successfully prepared by electrospinning technique and possessed good mechanical properties and magnetic responsiveness. The PCL/Fe3O4 scaffolds containing different Fe3O4 concentrations were free of cytotoxicity, indicating the good biocompatibility and low cytotoxicity of the scaffolds. The IKVAV-functionalized PCL/Fe3O4 scaffolds were able to guide and promote the directional extension of axons, the application of external magnetic field and the grafting of IKVAV peptides significantly further promoted the growth of DRGs and axons. The ELISA test results showed that the AP-10 F group scaffolds promoted the secretion of nerve growth factor (NGF) from DRG under a static magnetic field (SMF), thus promoting the growth and extension of axons. Importantly, the IKVAV-functionalized PCL/Fe3O4 scaffolds could significantly up-regulate the expression of Cntn2, PCNA, Sox10 and Isca1 genes related to adhesion, proliferation and magnetic receptor function under the stimulation of SMF. Therefore, IKVAV-functionalized PCL/Fe3O4 composite oriented scaffolds have potential applications in neural tissue engineering.

Immune-cell-mediated tissue engineering strategies for peripheral nerve injury and regeneration.

During the process of peripheral nerve repair, there are many complex pathological and physiological changes, including multi-cellular responses and various signaling molecules, and all these events establish a dynamic microenvironment for axon repair, regeneration, and target tissue/organ reinnervation. The immune system plays an indispensable role in the process of nerve repair and function recovery. An effective immune response not only involves innate-immune and adaptive-immune cells but also consists of chemokines and cytokines released by these immune cells. The elucidation of the orchestrated interplay of immune cells with nerve regeneration and functional restoration is meaningful for the exploration of therapeutic strategies. This review mainly enumerates the general immune cell response to peripheral nerve injury and focuses on their contributions to functional recovery. The tissue engineering-mediated strategies to regulate macrophages and T cells through physical and biochemical factors combined with scaffolds are discussed. The dynamic immune responses during peripheral nerve repair and immune-cell-mediated tissue engineering methods are presented, which provide a new insight and inspiration for immunomodulatory therapies in peripheral nerve regeneration.

Fabrication and Characterization of π-π Stacking Peptide-Contained Double Network Hydrogels.

Since the physical properties are similar to native extracellular matrices, double network (DN) hydrogels have been studied extensively in the tissue engineering. However, the double chemical crosslinked DN hydrogel is limited by poor fatigue resistance. π-π stacking is a non-covalent bonding interaction, which is essential to maintain and self-assemble the three-dimensional structure of biological proteins and nucleic acids. In this study, a robust polyethylene glycol diacrylate (PEGDA)/FFK hybrid DN hydrogel was prepared by Michael addition and π-π stacking. The hybrid DN hydrogels with π-π stacking interactions have excellent mechanical strength and fatigue resistance. The DN FFK/PEGDA hydrogels reveal great biocompatibility and hemocompatibility. The DN hydrogels containing π-π stacking have the potential to fabricate robust hybrid DN hydrogels in drug release and tissue engineering.

Recent progress and applications of poly(beta amino esters)-based biomaterials.

Poly(beta-amino esters, PBAEs) are a promising class of cationic polymers synthesized from diacrylates and amines via Michael addition. Recently, PBAEs have been widely developed for drug delivery, immunotherapy, gene therapy, antibacterial, tissue engineering and other applications due to their convenient synthesis, good bio-compatibility and degradation properties. Herein, we mainly summarize the recent progress in the PBAEs synthesis and their applications. The amine groups of PBAEs could be protonated in low pH environment, exhibiting proton sponge and pH-sensitive abilities. Furthermore, the positive PBAEs can interact with negative genes via electrostatic interactions for efficient delivery of nucleic acids. Moreover, positive PBAEs could also directly kill bacteria by disrupting their membranes at high doses. Finally, PBAEs can augment the immune responses, and improve the bioactivity of hydrogels in tissue engineering.

A bio-orthogonally functionalized chitosan scaffold with esterase-activatable release for nerve regeneration.

Developing nerve conduits with biological cues is a promising approach for repairing peripheral nerve injuries. Although most biological cues incorporated into conduits generally exert their biological functions at the surface, they could not be released into the on-demand regeneration sites under physiological conditions. Herein, we firstly report a bio-orthogonally functionalized chitosan scaffold with esterase-activatable release for peripheral nerve regeneration. In this study, biological cues are not only selectively conjugated into nerve conduits by bio-orthogonal reaction, but also precisely released in on-demand regeneration sites via esterase-activatable cleavage for peripheral nerve repair. Moreover, this nerve scaffold with esterase-activatable release could promote Schwann cells proliferation. In a rat sciatic nerve defect model, the bio-orthogonally functionalized scaffold with esterase-activatable release significantly increased sciatic nerve function recovery and improved target muscles weight. This strategy of incorporating esterase-activatable bioactive cues into peripheral nerve conduits offers great potential in preclinical studies.

A curcumin-induced assembly of a transferrin nanocarrier system and its antitumor effect.

To increase the solubility and targeting efficiency of curcumin (CCM) to tumors, transferrin (Tf)-CCM nanoparticles (NPs-CCM) with a CCM loading capacity of 5.2% were fabricated by Tf denaturation with hydrochloric acid, a denaturing agent, to open the hydrophobic cavity of Tf. The NPs-CCM were approximately 160 nm in size with a spherical shape. The solubility of the CCM in the nanoparticles was approximately 100,000 times greater than that of CCM alone (11 ng mL-1 vs 1.11 mg mL-1, respectively). The changes in the fluorescence spectra of Tf and 1-(anilinon)-aphthalene-8-sulfonic acid (ANS) in the NP-CCM preparation indicated that the polarity of certain hydrophobic and hydrophilic groups of Tf changed. CCM treatment of A549 cells resulted in a decrease in the mitochondrial membrane potential (MMP) and induced apoptosis through mitochondrial dependence. CCM increased the expression of phosphorylated c-Jun N-terminal kinase (JNK), P38, and extracellular signal-regulated kinase (ERK) but had a weak effect on the expression of nonphosphorylated JNK, P38, and ERK, which showed that the mitogen-activated protein kinase signaling (MAPK) transduction pathway is involved in CCM-mediated apoptosis. The half maximal inhibitory concentration (IC50) of NPs-CCM was higher than that of free CCM in A549 (16.41 ± 0.86 vs 12.51 ± 3.9 (µg mL-1), p = 0.036) and MCF-7 (9.31 ± 0.11 vs 2.44 ± 3.76 (µg mL-1), p < 0.0037) tumor cells, however the former had a greater tumor-targeting in vivo. Without the side effects of polyoxyethylene castor oil/ethanol as solvent, the hemolysis effect of NPs-CCM (0.05-1 mg mL-1) was notably lower than that of free CCM (p < 0.05). It was estimated that the half maximal lethal dose (LD50) of NPs-CCM was approximately two times that of CCM (100 mg kg-1 vs 50 mg kg-1), and the former had many advantages over that of free CCM in terms of lower toxicity and better targeting; thus, NPs-CCM can be administered at higher doses to acquire better antitumor effects than CCM alone, indicating that NPs-CCM are an effective and safe carrier for CCM delivery.

Construction and Biocompatibility Evaluation of Fibroin/Sericin-Based Scaffolds.

Because tissue responses to implants determine the success or failure of tissue engineering products, fibroin/sericin-based scaffolds including bionic silk scaffolds, native silk fibers, fibroin fibers, and regenerated fibroin have been fabricated, and their biocompatibility was investigated. Fibroin/sericin-based scaffolds were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Bionic silk scaffolds were beneficial to silk fiber formation through self-assembly. Histological and immunofluorescent staining analysis demonstrated that bionic silk scaffolds did not show significant inflammatory responses. Immunization analysis showed that soluble fibroin and sericin did not show obvious immunogenicity. This work supplied an effective approach to design fibroin/sericin-based scaffolds for tissue engineering and drug delivery.

Morphological changes of macrophages and their potential contribution to tendon healing.

Poor healing ability and adhesion formation greatly hinder the recovery of injured tendon function. Previously, our local sustained gene delivery system by using cyclooxygenases (COX-1 and COX-2)-engineered miRNA plasmid/nanoparticles loaded hydrogel significantly inhibited adhesion formation and promoted tendon healing. The present study aims to study morphological changes of the macrophages in the healing tendons after above treatment with the hydrogel. Firstly, we assessed the therapeutic effect of localized delivery of the hydrogel on cyclooxygenases in the injured rat Achilles tendon model. We found ultimate strengths of the healing tendons were significantly increased at week 2 and 3. We then studied the distribution of macrophages before and after tendon injury, and found macrophages were rapidly recruited into injured sites of tendons. After being isolated and cultured, macrophages were transfected with 6-Carboxyfluorescein (FAM) labeled siRNA/nanoparticles and presented a high transfection efficiency (>70%). We further compared the change of iNOS/CD206 in macrophages between negative control siRNA/nanoparticle group and COX siRNA/nanoparticle group. The major finding is that the morphology of the macrophages changed from type I macrophages to type II macrophages after transfection of COX siRNA/nanoparticles in vitro. Subsequently, rat Achilles tendon cells were cultured with supernatant collected from macrophages transfected with negative control siRNA/nanoparticles and COX siRNA/nanoparticles, and the proliferation of tendon cells was significantly increased in COX siRNA/nanoparticle supernatant group. Because type II macrophages are responsible for tissue repair, the changes in macrophage polarization from M1 to M2 may be one of the important events in promoting the tendon healing.

Bionic microenvironment-inspired synergistic effect of anisotropic micro-nanocomposite topology and biology cues on peripheral nerve regeneration.

Anisotropic topographies and biological cues can simulate the regenerative microenvironment of nerve from physical and biological aspects, which show promising application in nerve regeneration. However, their synergetic influence on injured peripheral nerve is rarely reported. In the present study, we constructed a bionic microenvironment-inspired scaffold integrated with both anisotropic micro-nanocomposite topographies and IKVAV peptide. The results showed that both the topographies and peptide displayed good stability. The scaffolds could effectively induce the orientation growth of Schwann cells and up-regulate the genes and proteins relevant to myelination. Last, three signal pathways including the Wnt/ß-catenin pathway, the extracellular signal-regulated kinase/mitogen-activated protein pathway, and the transforming growth factor-ß pathway were put forward, revealing the main path of synergistic effects of anisotropic micro-nanocomposite topographies and biological cues on neuroregeneration. The present study may supply an important strategy for developing functional of artificial nerve implants.

Sustained-Release Hydrogel-Based Rhynchophylline Delivery System Improved Injured Tendon Repair.

During the injured flexor tendon healing process, tendon tissue is easy to form extremely dense adhesion with the surrounding tissue, which causes the serious influence of hand function recovery. Uncaria is widely used in clinic and its main composition, Rhynchophylline (Rhy), has been reported on its good therapeutic effect, which could effectively inhibit the intra-abdominal adhesion formation. However, the therapeutic effect of Rhy on tendon healing and adhesion formation is still unclear. Due to the short half-life of Rhy, hyaluronic acid (HA) sustained-release system for Rhy delivery was constructed and it could also avoid drug from the undesired loss during the transit. After Rhy delivery system was applied around the injured tendons, adhesion formation, gliding function and healing strength of tendons were evaluated. Our results showed that the gliding excursion and healing strength of repaired tendons were both significantly increased, as well as the adhesion was inhibited. From in vivo experiments, Rhy could be able to increase the expression of Col Ⅰ/Col Ⅲ and helped fibroblasts to ordered organization for tendon tissues. But for adhesion tissues, Rhy promoted the apoptosis and accelerated the degradation of extracellular matrix. In vitro study showed Rhy could help tenocytes stimulated with TGF-ß1 to recover to normal cell functions involving cell proliferation and apoptosis level. Through high-throughput sequencing, we found that Rhy was involved in the regulation of Extracellular Matrix (ECM) signaling pathway. We draw a conclusion that Rhy enhanced the tendon healing and prevented adhesion formation through inhibiting the phosphorylation of Smad2. In a word, this sustained release system of Rhy may be a promising strategy for the treatment of injured tendons.

Brain-Targeted Dual Site-Selective Functionalized Poly(ß-Amino Esters) Delivery Platform for Nerve Regeneration.

Brain injuries are devastating central nervous system diseases, resulting in cognitive, motor, and sensory dysfunctions. However, clinical therapeutic options are still limited for brain injuries, indicating an urgent need to investigate new therapies. Furthermore, the efficient delivery of therapeutics across the blood-brain barrier (BBB) to the brain is a serious problem. In this study, a facile strategy of dual site-selective functionalized (DSSF) poly(ß-amino esters) was developed using bio-orthogonal chemistry for promoting brain nerve regeneration. Fluorescence colocalization studies demonstrated that these proton-sponge DSSF poly(ß-amino esters) targeted mitochondria through electrostatic interactions. More importantly, this delivery system could effectively accumulate in the injured brain sites and accelerate the recovery of the injured brain. Finally, this DSSF poly(ß-amino esters) platform may provide a new methodology for the construction of dual regioselective carriers in protein/peptide delivery and tissue engineering.

Nanoparticle-coated sutures providing sustained growth factor delivery to improve the healing strength of injured tendons.

Tendon injuries are common diseases. The healing capacity of tendon is limited due to its special composition of extra-cellular matrix and hypocellularity and hypovascularity. The purpose of this study was to evaluate the effectiveness of nanoparticle-coated sutures carrying growth factors for accelerating tendon repair. A variety of experimental methods had been used to investigate the characteristics and therapeutic effects of the modified sutures. Nanoparticles could adhere uniformly to the surface of the suture through polydopamine. Even sutured in the tendon, most of nanoparticles were still remained on the surface of suture, and the loaded proteins could spread into the tendon tissues. In vivo study, the ultimate strength of repaired tendons treated with bFGF and VEGFA-releasing sutures was significantly greater than the tendons repaired with control sutures at multiple time-points, whether in the chicken model of flexor tendon injury or the rat model of Achilles tendon injury. At week 6, the adhesion score in the bFGF and VEGFA-releasing suture group was significantly lower than those of the control suture group. Tendon gliding excursion was significantly longer in the bFGF and VEGFA-releasing suture group than that in the control bare sutures. Work of digital flexion was significantly decreased in the bFGF and VEGFA-releasing suture group. In a word, we developed a platform for local and continuous delivery of growth factors based on the nanoparticle-coated sutures, which could effectively deliver growth factors to tissues and control the release of growth factors. This growth factors delivery system is an attractive therapeutic tool to repair injured tendons. STATEMENT OF SIGNIFICANCE: Tendon rupture is a common clinical injury, due to the special character of the tendon with mainly extra cellular matrix and hypocellularity and hypovascularity, the healing capacity of the injured tendon is limited. In this study, nanoparticle-coated surgical sutures carrying growth factors were prepared to accelerate tendon repair. After treatment, bFGF and VEGFA loaded nanoparticle-coated sutures can significantly enhance tendon healing, and significantly improve tendon gliding function and effectively inhibit the formation of adhesion. Moreover, these nanoparticle-coated sutures have good biocompatibility and no obvious tissue reaction, which provides more guarantee for further clinical application. This is an attractive and promising approach that uses surgical suture as a growth factor delivery tool to repair tendon injury, which can simplify the treatment. And this kind of bioactive sutures may be applied to other tissue repair, such as muscle, nerve, intestinal canal, blood vessel, skin, and so on.

Soft hydrogel promotes dorsal root ganglion by upregulating gene expression of Ntn4 and Unc5B.

Mechanical property is an important factor of cellular microenvironment for neural tissue regeneration. In this study, polyacrylamide (PAM) hydrogels with systematically varying elastic modulus were prepared using in situ radical polymerization. We found that the hydrogel was biocompatible, and the length of dorsal root ganglion (DRG)'s axon and cell density were optimal on the hydrogels with elastic modulus of 5.1 kPa (among hydrogels with elastic modulus between 3.6 kPa and 16.5 kPa). These DRGs also exhibited highest gene and protein expression of proliferation marker Epha4, Ntn4, Sema3D and differentiation marker Unc5B. Our study revealed the mechanism of how material stiffness affects DRG proliferation and differentiation. It will also provide theoretical basis and evidence for the design and development of nerve graft with better repair performance.

Effects of nanoparticle-mediated growth factor gene transfer to the injured microenvironment on the tendon-to-bone healing strength.

The tendon-to-bone healing after trauma is usually slow and weak, and the repair site is easily disrupted during early mobilization exercise. bFGF and VEGFA gene therapy may hold promise in augmenting the tendon-to-bone healing process through enhancing cell proliferation and angiogenesis. This study is conducted to determine the effects of nanoparticle-mediated co-delivery of bFGF and VEGFA genes to the tendon-to-bone repair interface on the healing strength and biological responses in a chicken model. The PLGA nanoparticle/pEGFP-bFGF + pEGFP-VEGFA plasmid complexes were prepared and were characterized in vitro and in vivo. The nanoparticle/plasmid complexes can effectively transfer bFGF and VEGFA genes to the tendon-to-bone interface. Nanoparticle-mediated co-delivery of bFGF and VEGFA genes significantly improved the tendon-to-bone healing in terms of healing strengths and histology in a chicken flexor tendon repair model. Our results suggest a new biological approach to accelerate the tendon-to-bone healing.

Preparation of doxorubicin-loaded collagen-PAPBA nanoparticles and their anticancer efficacy in ovarian cancer.

BACKGROUND: The aims of this study were to prepare the collagen-poly (3-acrylamidophenylboronic acid) nanoparticles (collagen-PAPBA NPs) encapsulating doxorubicin (DOX) and research their anticancer efficacy in ovarian cancer. METHODS: Collagen-PAPBA NPs were prepared, and their morphology and stability morphology were observed by transmission electron microscopy (TEM) and dynamic light scattering system (DLS). Preparation of doxorubicin-loaded Collagen-PAPBA NPs (DOX-loaded NPs) were then prepared, and the drug-loading content, encapsulation efficiency, and in vitro drug-release profiles were calculated. The morphology of DOX-loaded NPs was also observed by DLS, in vitro cytotoxicity to A2780 cells was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, in vitro antitumor activity on A2780 cells was observed by immunofluorescence, and in vivo antitumor activity was assessed using an experimental BALB/c mice tumor model. RESULTS: DOX-encapsulating collagen-PAPBA NPs were successfully prepared with mediation by biomolecule. The average hydrodynamic diameter of collagen-PAPBA NPs as measured by DLS was about 79 nm, with a homogeneous distribution of size. TEM revealed that nanoparticles were well-dispersed, spherical, and a roughly uniform 75 nm in size. Collagen-PAPBA NPs were quite stable in a wide range of pH and temperature conditions and associated with the concentration of glucose. DLS revealed that the average hydrodynamic diameter of DOX-loaded NPs was about 81.3 nm, with homogeneous distribution of size. TEM revealed that drug-loaded nanoparticles were spherical, well-dispersed, and gad a roughly uniform size of 79 nm. The proportion of DOX loaded into the nanoparticles was 10%, while the encapsulating efficiency was 97%. The result of the releasing test showed that the drug-loaded nanoparticles, as carriers for DOX, had a good sustained-release effect. The cell toxicity experiment showed that the blank NPs had no cytotoxicity to A2780 cells, and that the drug-loaded NPS had good a sustained-release function. They may thus have potential toxic-reducing side effects. CONCLUSIONS: Under the same doses, the drug-loaded NP had a superior inhibitory effect to free DOX on the growth of human ovarian cancer.

Construction of Dual-Biofunctionalized Chitosan/Collagen Scaffolds for Simultaneous Neovascularization and Nerve Regeneration.

Biofunctionalization of artificial nerve implants by incorporation of specific bioactive factors has greatly enhanced the success of grafting procedures for peripheral nerve regeneration. However, most studies on novel biofunctionalized implants have emphasized the promotion of neuronal and axonal repair over vascularization, a process critical for long-term functional restoration. We constructed a dual-biofunctionalized chitosan/collagen composite scaffold with Ile-Lys-Val-Ala-Val (IKVAV) and vascular endothelial growth factor (VEGF) by combining solution blending, in situ lyophilization, and surface biomodification. Immobilization of VEGF and IKVAV on the scaffolds was confirmed both qualitatively by staining and quantitatively by ELISA. Various single- and dual-biofunctionalized scaffolds were compared for the promotion of endothelial cell (EC) and Schwann cell (SC) proliferation as well as the induction of angiogenic and neuroregeneration-associated genes by these cells in culture. The efficacy of these scaffolds for vascularization was evaluated by implantation in chicken embryos, while functional repair capacity in vivo was assessed in rats subjected to a 10 mm sciatic nerve injury. Dual-biofunctionalized scaffolds supported robust EC and SC proliferation and upregulated the expression levels of multiple genes and proteins related to neuroregeneration and vascularization. Dual-biofunctionalized scaffolds demonstrated superior vascularization induction in embryos and greater promotion of vascularization, myelination, and functional recovery in rats. These findings support the clinical potential of VEGF/IKVAV dual-biofunctionalized chitosan/collagen composite scaffolds for facilitating peripheral nerve regeneration, making it an attractive candidate for repairing critical nerve defect. The study may provide a critical experimental and theoretical basis for the development and design of new artificial nerve implants with excellent biological performance.

Synthesis and Evaluation of Cytocompatible Alkyne-Containing Poly(ß-amino ester)-Based Hydrogels Functionalized via Click Reaction.

Although poly(ß-amino esters) (PAEs) have been widely applied in nonviral gene transfection, drug delivery systems, and regenerative medicine, the multifunctional modification of PAEs and bio-orthogonal strategies of PAE-based hydrogel functionalization is still a challenge. Herein, a strategy of poly(ß-amino ester)-based hydrogel functionalization was developed via bio-orthogonal reactions in this study. Acrylate-terminated poly(ß-amino esters) containing alkyne groups were synthesized by Michael addition reaction. Alkyne groups on poly(ß-amino esters) could conjugate bioactive molecules with azide of K(N3)RGD via copper-catalyzed azide-alkyne cycloaddition, and terminal acrylate groups could in situ polymerize to prepare a hydrogel. A biomimetic peptide K(N3)RGD functionalized hydrogel was prepared by polymerization of acrylate-terminated poly(ß-amino esters) containing conjugated peptide and polyethylene glycol diacrylate (PEGDA). The storage modulus and mechanical properties exhibited an increased trend with the increased concentration; nevertheless, swelling ratio and surface wetting properties demonstrated a decreased tendency by increased concentrations. Cell proliferation and live/dead staining showed that Schwann cells plated on the hydrogel with an elastic modulus of 25.39 KPa are more suitable for proliferation and function exertion of Schwann cells compared with that of 42.11 and 57.86 KPa, and KRGD-conjugated hydrogel could increase the elongation of Schwann cells relative to nonconjugated hydrogels. This azide-alkyne strategy may be a promising candidate for hydrogel functionalization in tissue engineering and other biomedical applications.

Construction of Biofunctionalized Anisotropic Hydrogel Micropatterns and Their Effect on Schwann Cell Behavior in Peripheral Nerve Regeneration.

Hydrogels have promising application in tissue regeneration due to their excellent physicochemical and biocompatible properties, whereas anisotropic micropatterns are been proven to directionally induce cell alignment and accelerate cell migration. However, an effect of biofunctionalized anisotropic hydrogel micropatterns on nerve regeneration has rarely been reported. In this study, the anisotropic polyacrylamide (PAM) hydrogel micropatterns with aligned ridge/groove structures were first prepared via in situ free radical polymerization and micromolding, and then biofunctionalized using YIGSR peptide for better promoting cell growth. The morphology, swelling ratio, wettability, mechanical properties, and stability of the prepared hydrogel were characterized. The successful immobilization of YIGSR peptide on the PAM hydrogel was monitored using FTIR, immunofluorescence staining, and ELISA. The effects on adhesion, directional growth, and biological function of Schwann cells were evaluated. The results displayed that the anisotropic PAM hydrogel micropatterns with inner porous structure possessed good stability, swelling, and mechanical properties. The YIGSR peptide could be well immobilized on hydrogel micropatterns with a percentage of 62.6%. The biofunctionalized anisotropic hydrogel micropatterns could effectively regulate the orientation growth of Schwann cells, and obviously up-regulate BDNF (40%) and ß-actin (50%) expression compared with single hydrogel micropatterns, without negatively affecting the normal secretion of neurotropic factors by Schwann cells. To the best of our knowledge, this is the first time to study the construction and effect of biofunctionalized anisotropic hydrogel micropatterns on nerve regeneration, which may provide an experimental and theoretical basis for the design and development of artificial implants for nerve regeneration application.

Gene-Loaded Nanoparticle-Coated Sutures Provide Effective Gene Delivery to Enhance Tendon Healing.

How to accelerate tendon healing remains a clinical challenge. In this study, a suture carrying nanoparticle/pEGFP-basic fibroblast growth factor (bFGF) and pEGFP-vascular endothelial growth factor A (VEGFA) complexes was developed to transfer the growth factor genes into injured tendon tissues to promote healing. Polydopamine-modified sutures can uniformly and tightly absorb nanoparticle/plasmid complexes. After tendon tissues were sutured, the nanoparticle/plasmid complexes still existed on the suture surface. Further, we found that the nanoparticle/plasmid complexes delivered into tendon tissues could diffuse from sutures to tendon tissues and effectively transfect genes into tendon cells, significantly increasing the expression of growth factors in tendon tissues. Finally, biomechanical tests showed that nanoparticle/pEGFP-bFGF and pEGFP-VEGFA complex-coated sutures could significantly increase the ultimate strengths of repaired tendons, especially at 4 weeks after operation. Two kinds of nanoparticle/plasmid complex-coated sutures significantly increased flexor tendon healing strength by 3.7 times for Ethilon and 5.8 times for PDS II, respectively, compared with the corresponding unmodified sutures. In the flexor tendon injury model, at 6 weeks after surgery, compared with the control suture, the nanoparticle/plasmid complex-coated sutures can significantly increase the gliding excursions of the tendon and inhibit the formation of adhesion. These results indicate that this nanoparticle/plasmid complex-coated suture is a promising tool for the treatment of injured tendons.

Correlation between patients' age and cancer immunotherapy efficacy.

Background: Although immunosenescence-induced difference on overall immune function and immune cell subsets between younger and older populations has been well characterized, the potential effect of patients' age on the efficacy of immune checkpoint inhibitors (ICIs) remains little known. We performed a meta-analysis to investigate whether age differences play a role in cancer immunotherapy efficacy based on a large amount of clinical data. Methods: We conducted a systematic search of PubMed, Embase and MEDLINE for relevant randomized controlled trials. The primary outcome was overall survival (OS) and progression-free survival (PFS) was secondary outcome. The interaction test was used to assess the heterogeneity of HR between younger and older groups. Results: In total, 19 clinical randomized trials involving 11157 patients were included. The pooled HR for OS was 0.73 (95% CI 0.69-0.78) and 0.63 (95% CI 0.52-0.73) for PFS in younger patients receiving ICIs treatments, when compared with younger patients treated with controls. For older patients treated with ICIs, the pooled HR for OS compared with controls was 0.64 (95% CI 0.59-0.69) and 0.66 (95% CI 0.58-0.74) for PFS. The difference on OS efficacy between younger and older patients treated with ICIs was significant (Pheterogeneity = 0.025). Conclusions: Immune checkpoint inhibitors significantly improved OS and PFS in both younger and older patients compared with controls, but the magnitude of benefit was clinically age-dependent. Patients ≥65 y can benefit more from immunotherapy than younger patients. Future research should take age difference into consideration in trials and focus on tolerance and toxicity of ICIs in older patients.