Sodium alginate/collagen hydrogel loaded with human umbilical cord mesenchymal stem cells promotes wound healing and skin remodeling.

Stem cell transplantation is a promising therapy for wound healing, but the low retention and survival of transplanted stem cells limit their application. Injectable hydrogels exert beneficial effects in skin tissue engineering. In this study, an injectable hydrogel composed of sodium alginate (SA) and collagen type I (Col) was synthesized as a tissue scaffold to improve the efficacy of stem cells in a full-thickness excision wound model. Our results showed that SA/Col hydrogel was injectable, biodegradable, and exhibited low immunogenicity, which could promote the retention and survival of hUC-MSCs in vivo. SA/Col loaded with hUC-MSCs showed reduced wound size (p < 0.05). Histological and immunofluorescence results confirmed that SA/Col loaded with hUC-MSCs significantly promoted the formation of granulation, enhanced collagen deposition and angiogenesis, increased VEGF and TGF-ß1 expression (p < 0.05), and mitigated inflammation evidenced by lower production of TNF-α and IL-1ß and higher release of IL-4 and IL-10 (p < 0.05). Furthermore, SA/Col loaded with hUC-MSCs significantly lowered the expression of NLRP3 inflammasome-related proteins (p < 0.05). Taken together, our results suggest that SA/Col loaded with hUC-MSCs promotes skin wound healing via partly inhibiting NLRP3 pathway, which has potential to the treatment of skin wounds.

Surface modification of esophageal stent materials by a polyethylenimine layer aiming at anti-cancer function.

Esophageal cancer is difficult to cure globally and possesses high mortality rate, and it is generally accepted that palliative care such as stent implantation is the main therapy method for esophageal cancer in later period. However, the restenosis caused by tumor cells and inflammatory cells seriously interferes the stent clinical application and limits its long-term services. To solve this problem, series of drug delivery stents were developed and proven rather effective in the early stage of implantation, but more serious restenosis occurred after the drug delivery was over, which endangered the patients' life. Therefore, endowing the esophageal stent continuous anti-cancer function become an ideal strategy for inhibiting the restenosis. In this contribution, the functional layer composed of polydopamine (PDA) and Poly-ethylenimine (PEI) with series of molecular weights (MW, 1.8 × 103, 1 × 104, 2.5 × 104 and 7 × 104 Da) were fabricated onto the esophageal stent material 317L stainless steel (317L SS) surface. The surface characterization including amine quantitative, atomic force microscopy (AFM) and water contact angle measurement indicated successful preparation of the PDA/PEI layer. The Eca109 cells culture results proved that the PDA/PEI layers significantly improve Eca109 cells apoptosis and necrosis, suggesting excellent anti-cancer function. In addition, we also found that the anti-cancer function of the PDA/PEI layers was positively correlated to the immobilized PEIs' MW. All the results demonstrated the potential application of the PDA/PEI layers on the surface modification of esophageal stent for continuous anti-cancer function. It is generally accepted that the restenosis caused by tumor cells seriously interferes the esophageal stent clinical application. Thus, endowing the esophageal stent continuous anti-cancer function is the ideal strategy for inhibiting the restenosis. In this work, we fabricated functional layers composed of polydopamine (PDA) and Poly-ethylenimine (PEI) with series of molecular weights (MW, 1.8 × 103, 1 × 104, 2.5 × 104 and 7 × 104 Da) onto the esophageal stent material 317L stainless steel (317L SS) surface to inhibit the tumor cells growth, and this function was related to the PEIs' molecular weights. The functional PDA/PEI layers were expected potentially applied for surface modification of esophageal stent materials.

Constructing bio-layer of heparin and type IV collagen on titanium surface for improving its endothelialization and blood compatibility.

The modification of cardiovascular stent surface for a better micro-environment has gradually changed to multi-molecule, multi-functional designation. In this study, heparin (Hep) and type IV collagen (IVCol) were used as the functional molecule to construct a bifunctional micro-environment of anticoagulation and promoting endothelialization on titanium (Ti). The surface characterization results (AFM, Alcian Blue 8GX Staining and fluorescence staining of IVCol) indicated that the bio-layer of Hep and IVCol were successfully fabricated on the Ti surface through electrostatic self-assembly. The APTT and platelet adhesion test demonstrated that the bionic layer possessed better blood compatibility compared with Ti surface. The adhesion, proliferation, migration and apoptosis tests of endothelial cells proved that the Hep/IVCol layer was able to enhance the endothelialization of the Ti surface. The in vivo animal implantation results manifested that the bionic surface could encourage new endothelialization. This work provides an important reference for the construction of multifunction micro-environment on the cardiovascular scaffold surface.

Ultra-stretchable, tissue-adhesive, shape-adaptive, self-healing, on-demand removable hydrogel dressings with multiple functions for infected wound healing in regions of high mobility.

Bacterial infection in the most mobile area usually leads to delayed healing and functional restriction, which has been a long-term challenge in clinic. Developing hydrogel-based dressings with mechanical flexibly, high adhesive and anti-bacterial properties, will contribute to the healing and therapeutic effects especially for this typical skin wound. In this work, composite hydrogel named PBOF through multi-reversible bonds between polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion demonstrated a 100 times ultra-stretch ability, 24 kPa of highly tissue-adhesive, rapid shape-adaptability within 2 min and self-healing feature within 40 s, was designed as the multifunctional wound dressing for the Staphylococcus aureus-infected skin wound in the mice nape model. Besides, this hydrogel dressing could be easily removed on-demand within 10 min by water. The rapid disassembly of this hydrogel is related to the formation of hydrogen bonds between polyvinyl alcohol and water. Moreover, the multifunctional properties of this hydrogel include strong anti-oxidative, anti-bacteria and hemostasis derived from oligomeric procyanidin and photothermal effect of ferric ion/polyphenol chelate. The killing ratio of the hydrogel on Staphylococcus aureus in infected skin wound reached 90.6% when exposed to 808 nm irradiation for 10 min. Simultaneously, reduced oxidative stress, suppressed inflammation, and promoted angiogenesis all together accelerated wound healing. Therefore, this well-designed multifunctional PBOF hydrogel holds great promise as skin wound dressing especially in the high mobile regions of the body. STATEMENT OF SIGNIFICANCE: An ultra-stretchable, highly tissue-adhesive, and rapidly shape-adaptive, self-healing and on-demand removable hydrogel based on multi-reversible bonds among polyvinyl alcohol, borax, oligomeric procyanidin and ferric ion is designed as dressing material for infected wound healing in the movable nape. The rapid on-demand removal of the hydrogel relates to the formation of hydrogen bonds between polyvinyl alcohol and water. This hydrogel dressing shows strong antioxidant capacity, rapid hemostasis and photothermal antibacterial ability. This is derived from oligomeric procyanidin and thephotothermal effect of ferric ion/polyphenol chelate, which eliminates bacterial infection, reduces oxidative stress, regulates inflammation, promotes angiogenesis, and finally accelerates the infected wound healing in movable part.

Nanocomposite multifunctional hyaluronic acid hydrogel with photothermal antibacterial and antioxidant properties for infected wound healing.

Bacterial infection and subsequent reactive oxygen species (ROS) damage are major factors that delay wound healing in infected skin. Recently, photothermal therapy (PTT), as a new antibacterial method, has shown great advantages in the treatment of infected skin wound. Antibacterial and antioxidant hydrogels can reduce bacterial colonization and infection, scavenge ROS, relieve inflammation, and accelerate wound healing. In this study, an enzyme-crosslinked hyaluronic acid-tyramine (HT) hydrogel loaded with antioxidant and photothermal silver nanoparticles (AgNPs), named HTA, was developed as functional wound dressing to promote the infected skin wound healing. Natural antioxidant tannic acids (TA) were used as both reducing and stabilizing agents to facilely synthesize the silver nanoparticles capped with TA (AgNPs@TA). The incorporation of AgNPs@TA significantly enhanced the antioxidant, antibacterial, photothermal antibacterial, adhesive, and hemostatic abilities of the resulted HTA hydrogel. Besides, HTA hydrogel has rapid gelation, well injection and biocompatibility. In vivo results on the Staphylococcus aureus and Escherichia coli co-infected mouse skin wound model showed that HTA0.4 (containing 0.4 mg/mL AgNPs@TA) hydrogel combined with near infrared ray radiation highly alleviated inflammation, promoted angiogenesis, and accelerated the healing process. Therefore, this nanocomposite hydrogel wound dressing with antibacterial and antioxidant capabilities has great application potential in the treatment of infected skin wounds.

PMN-incorporated multifunctional chitosan hydrogel for postoperative synergistic photothermal melanoma therapy and skin regeneration.

Melanoma excision surgery is usually accompanied by neoplasm residual, tissue defect, and bacterial infection, resulting in high tumor recurrence and chronic wound. Nanocomposite hydrogels can satisfy the twin requirements of avoiding tumor recurrence and skin wound healing following skin melanoma surgery due to their photothermal anti-tumor and anti-bacterial activities. In this study, carboxymethyl chitosan, oxidized fucoidan and polyphenol-metal nanoparticle (PMN) of tannic acid capped gold nanoparticles were used to fabricate multifunctional nanocomposite hydrogels through Schiff base reaction. The prepared hydrogel demonstrated outstanding photothermal effect, and the controlled high temperature will rapidly kill melanoma cells as well as bacteria within 10 min. Good injectability, self-healing and adhesion combined with high reactive oxygen species (ROS) scavenging capacity, hemostasis and biocompatibility made this hydrogel platform perfect for the postoperative treatment of melanoma and promoting wound healing. With the assistance of NIR irradiance, hydrogel can inhibit tumor tissue proliferation and promote tumor cell apoptosis, thereby helping to prevent melanoma recurrence after surgical removal of tumors. Simultaneously, the irradiance heat and polyphenol component kill bacteria on the wound surface, eliminate ROS, inhibit inflammatory responses, and promote angiogenesis, collagen deposition, and skin regeneration, all of which help to speed up wound healing.

Injectable and reactive oxygen species-scavenging gelatin hydrogel promotes neural repair in experimental traumatic brain injury.

Oxidative stress caused by the overexpression of reactive oxygen species (ROS) plays an important role in the pathogenesis of traumatic brain injury (TBI). Accumulation of ROS can lead to cell death, neurodegeneration, and neurological deficit. Therefore, the design and application of functional materials with ROS scavenging ability is of great significance for neural repair. Herein, an injectable and antioxidant hydrogel was developed for TBI treatment based on the Schiff base reaction of gallic acid-conjugated gelatin (GGA) and oxidized dextran (Odex). The resulting GGA/Odex hydrogel could effectively scavenge DPPH and ABTS radicals, as well as protect cells from the oxidative damage in vitro. Moreover, GGA/Odex hydrogel possessed well biocompatible features. In a moderate TBI mouse model, in situ implantation of GGA6Odex hydrogel efficiently facilitated neurogenesis and promoted the motor, learning and memory abilities. Also, this composite hydrogel suppressed oxidative stress and inflammation via the activation of Nrf2/HO-1 pathway and the regulating of inflammatory factors secretion and macrophage/microglia polarization. Therefore, this injectable and ROS-scavenging GGA6Odex hydrogel is a promising biomaterial for tissue regenerative medicine, including TBI and other tissue repair relevant to raised ROS circumstance.

Facile preparation of PVA hydrogels with adhesive, self-healing, antimicrobial, and on-demand removable capabilities for rapid hemostasis.

Multifunctional and smart hydrogel-based hemostatic materials are of great significance in the field of medical care. In this paper, a facile method for the preparation of self-healing, adhesive and on-demand removable PBO hydrogels was established with a simple mixture of polyvinyl alcohol (PVA), borax and oligomeric procyanidin (OPC). In this hydrogel system, borax and OPC were used as dynamic crosslinkers to connect the PVA macromolecules through reversible borate ester bonds and hydrogen bonds, resulting in hydrogels that possess good self-healing and adhesive abilities. Furthermore, the PBO hydrogel displayed excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. In addition, thanks to the adhesive property of the hydrogel and the inherent hemostatic activity of OPC, this hydrogel showed rapid hemostasis performance as concluded from the in vivo experiments of mouse liver incision, tail amputation and femoral artery models. Benefitting from the fast degradation in water, this hydrogel could be easily removed on-demand within 10 min. Therefore, this well-designed PBO hydrogel offers an important prospect as a rapid hemostatic dressing.

Hyaluronic acid/polyethyleneimine nanoparticles loaded with copper ion and disulfiram for esophageal cancer.

In the clinical treatment of cancer, improving the effectiveness and targeting of drugs has always been a bottleneck problem that needs to be solved. In this contribution, inspired by the targeted inhibition on cancer from combination application of disulfiram and divalent copper ion (Cu2+), we optimized the concentration of disulfiram and Cu2+ ion for inhibiting esophageal cancer cells, and loaded them in hyaluronic acid (HA)/polyethyleneimine (PEI) nanoparticles with specific scales, in order to improve the effectiveness and targeting of drugs. The in vitro cell experiments demonstrated that more drug loaded HA/PEI nanoparticles accumulated to the esophageal squamous cell carcinoma (Eca109) and promoted higher apoptosis ratio of Eca109. Both in vitro and in vivo biological assessment verified that the disulfiram/Cu2+ loaded HA/PEI nanoparticles promoted the apoptosis of cancer cells and inhibited the tumor proliferation, but had no toxicity on other normal organs.

PDGF-BB/SA/Dex injectable hydrogels accelerate BMSC-mediated functional full thickness skin wound repair by promoting angiogenesis.

Wound healing is a well-orchestrated dynamic and interactive process, which needs a favorable microenvironment and suitable angiogenesis. Platelet derived growth factor-BB (PDGF-BB) plays a crucial role in wound healing. However, the short half-life of PDGF-BB limits its efficacy. In the present study, we successfully synthesized an injectable hydrogel with sodium alginate (SA) and dextran (Dex) as a delivery system to simultaneously deliver PDGF-BB and bone marrow-derived mesenchymal stem cells (BMSCs) in the wound. Our work demonstrates that the PDGF-BB protein enhanced the survival, migration and endothelial cell (EC) differentiation of BMSCs in vitro. The PDGF-BB/SA/Dex hydrogels could sustainably release PDGF-BB with excellent biocompatibility in vitro and in vivo. Besides, these composite hydrogels loaded with BMSCs could accelerate wound healing by improving epithelialization and collagen deposition. In addition, the PDGF-BB/SA/Dex hydrogels promoted the EC-differentiation of transplanted BMSCs and proliferation of hair follicle stem cells in the wound. Furthermore, the expressions of angiogenesis-specific markers, PDGFR-ß, p-PI3K, p-Akt, and p-eNOS, were obviously increased in the PDGF-BB/SA/Dex/BMSCs group. In conclusion, the PDGF-BB/SA/Dex injectable hydrogels could accelerate BMSC-mediated skin wound healing by promoting angiogenesis via the activation of the PDGF-BB/PDGFR-ß-mediated PI3K/Akt/eNOS pathway, which may provide a new therapeutic strategy for stem cell therapy in wound healing.

The mechanism of PDA/PEI/5-Fu coated esophageal stent material on inhibiting cancer associated pathological cells.

Metal stent implantation is usually applied to alleviate nonoperative palliative esophageal obstruction for esophageal cancer in the later period. However, in-stent restenosis after stent implantation limits the esophageal stents' performance due to lack of effective suppression of pathological cells from cancer microenvironment. In previous work, we modified the esophageal stent material 317L stainless steel (317LSS) surface with a poly-dopamine/poly-ethylenimine/5-fluorouracil layer (PDA/PEI/5-Fu), which had strong anti-tumor and anti-restenosis functions. Nevertheless, the mechanism of PDA/PEI/5-Fu layer against tumor and inflammation remains unclear. In this work, we revealed the mechanism of PDA/PEI/5-Fu suppressing the esophageal cancer related pathological cells (esophageal tumor cells, epithelial cells, and fibroblast) and inflammatory cells (macrophages) via series of experiments. Our data suggested that the PEI inhibited viability and E-cadherin expression of the pathological cells, and blocked the NF-κB signal pathway (reducing levels of p-NF-κB proteins). The loaded 5-Fu inhibited the inflammatory factors (TNF-α and IL-1ß) release and promoted the anti-inflammation/anti-tumor factors (IL-10 and IL-4) release from macrophages, and also suppressed pathological cells migration; both the PEI and 5-Fu contributed to the upregulation of Bax and Caspase-3 (pro-tumor-apoptosis factor), as well as the downregulation of Bcl-2 (anti-tumor-apoptosis factor) in esophageal tumor cells. All the results showed that PDA/PEI/5-Fu coating had potential multipath anti-cancer and anti-inflammatory effects in the surface modification of esophageal stents.

Control the fate of human umbilical cord mesenchymal stem cells with dual-enzymatically cross-linked gelatin hydrogels for potential applications in nerve regeneration.

Stem-cell-based therapy is a promising strategy to treat challenging neurological diseases, while its application is hindered primarily by the low viability and uncontrolled differentiation of stem cell. Hydrogel can be properly engineered to share similar characteristics with the target tissue, thus promoting cell viability and directing cell differentiation. In this study, we proposed a new dual-enzymatically cross-linked and injectable gelatin hydrogel for regulating survival, proliferation, and differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in a three-dimensional matrix. This injectable gelatin hydrogel was formed by oxidative coupling of gelatin-hydroxyphenyl acid conjugates catalyzed by hydrogen horseradish peroxidase (HRP) and choline oxidase (ChOx). Modulus and H2 O2 release can be well controlled by ChOx activity. Results from calcein-AM/PI staining and Ki67 immunofluorescence tests demonstrated that the survival and proliferation behavior of hUC-MSCs were highly enhanced in HRP1U ChOx0.25U hydrogel with lower modulus and less H2 O2 release compared with other groups. Attractively, the expression of neuron-specific markers ß-III tubulin, neurofilament light chain (NFL), and synapsin-1 was significantly increased in HRP1U ChOx0.25U hydrogel as well. Additionally, in vitro hemolysis test and in vivo HE staining data highlighted the good biocompatibility. Undoubtedly, this injectable gelatin hydrogel's ability to control hUC-MSCs' fate holds enormous potentials in nervous disorders' therapy and nerve regeneration.

A chitosan-based thermosensitive scaffold loaded with bone marrow-derived mesenchymal stem cells promotes motor function recovery in spinal cord injured mice.

Spinal cord injury is a devastating trauma with high mortality and disability, for which there is no effective treatment. Stem cell-based tissue engineering has been reported to promote functional neural recovery. At present, building a neural scaffold with excellent biocompatibility for cells and tissues is still challenging. In this study, a new thermosensitive composite hydrogel based on chitosan, hydroxyethyl cellulose, collagen and ß-phosphoglycerate (CS-HEC-Col/GP hydrogel) is developed to encapsulate murine bone marrow-derived mesenchymal stem cells (BMSCs) to improve therapeutic efficacy in spinal cord injured mice. This composite hydrogel possesses a good cytocompatibility to mouse BMSCs by live/dead staining, minimized inflammatory reaction in vivo by hematoxylin and eosin staining and suitable rheological behavior similar to neural tissue, ranging from 100 to 1000 Pa. Furthermore, the data from animal experiments indicated that BMSC-loaded CS-HEC-Col/GP hydrogel could enhance the survival or proliferation of endogenous nerve cells, probably by secreting neurotrophic factors and inhibiting apoptosis, and thereby promote the recovery of motor function in the hindlimbs of a murine spinal cord injury model.

Dual-enzymatically crosslinked hyaluronic acid hydrogel as a long-time 3D stem cell culture system.

Stem cell-based tissue engineering shows enormous potential for regenerative medicine. Three-dimensional (3D) stem cell culture is the most basic aspect of tissue engineering. However, achievement of a perfect scaffold for highly efficient 3D cell culture is currently still limited. Herein, a new hyaluronic acid hydrogel dual-enzymatically crosslinked by horseradish peroxidase and choline oxidase is developed as a 3D stem cell culture system. This hydrogel possesses superior stability over two months, controllable biodegradability with hyaluronidases, a high swelling ratio exceeding 6000%, and excellent cytocompatibility in vitro and biocompatibility in vivo. More importantly, a long-time and highly cellular activity 3D culture of bone marrow-derived mesenchymal stem cells was achieved in vitro over 20 days. All these encouraging results highlight the great potential of this new hydrogel for 3D culture and tissue engineering.

Production and characterization of cellulolytic enzymes from the thermoacidophilic fungal Aspergillus terreus M11 under solid-state cultivation of corn stover.

The production of extracellular cellulases by a newly isolated thermoacidophilic fungus, Aspergillus terreus M11, on the lignocellulosic materials was studied in solid-state fermentation (SSF). The results showed that the high-level cellulase activity was produced at 45 degrees C pH 3 and moisture 80% with corn stover and 0.8% yeast extract as carbon and nitrogen sources. 581 U endoglucanase activity, 243 U filter paper activity and 128 U beta-glucosidase activity per gram of carbon source were obtained in the optimal condition. Endoglucanase and beta-glucosidase exhibited their maximum activity at pH 2 and pH 3, respectively, and both of them showed remarkable stability in the range of pH 2-5. The activities of endoglucanase and beta-glucosidase were up to the maximum at 70 degrees C and maintained about 65% and 53% of their original activities after incubation at 70 degrees C for 6h. The enzyme preparations from this strain were used to hydrolyze Avicel. Higher hydrolysis yields of Avicel were up to 63% on 5% Avicel (w/v) for 72 h with 20 U FPase/g substrate.

Biocompatibility of quantum dots (CdSe/ZnS ) in human amniotic membrane-derived mesenchymal stem cells in vitro.

BACKGROUND AND AIM: Amniotic membrane-derived mesenchymal stem cells (hAM-dMSCs) are a potential source of mesenchymal stem cells which could be used to repair skin damage. The use of mesenchymal stem cells to repair skin damage requires safe, effective and biocompatible agents to evaluate the effectiveness of the result. Quantum dots (QDs) composed of CdSe/ZnS are semiconductor nanocrystals with broad excitation and narrow emission spectra, which have been considered as a new chemical and fluorescent substance for non-invasively labeling different cells in vitro and in vivo. This study investigated the cytotoxic effects of QDs on hAM-dMSCs at different times following labeling. METHODS: Using 0.75, 1.5 and 3.0 µL between quantum dots, labeled human amniotic mesenchymal stem cells were collected on days 1, 2 and 4 and observed morphological changes, performed an MTT cell growth assay and flow cytometry for mesenchymal stem cells molecular markers. RESULTS: Quantum dot concentration 0.75 µg/mL labeled under a fluorescence microscope, cell morphology was observed, The MTT assay showed cells in the proliferative phase. Flow cytometry expression CD29, CD31, CD34, CD44, CD90, CD105 and CD106. CONCLUSIONS: Within a certain range of concentrations between quantum dots labeled human amniotic mesenchymal stem cells has good biocompatibility.

Biocompatibility of nano-hydroxyapatite/Mg-Zn-Ca alloy composite scaffolds to human umbilical cord mesenchymal stem cells from Wharton's jelly in vitro.

Seeding cells and scaffolds play pivotal roles in bone tissue engineering and regenerative medicine. Wharton's jelly-derived mesenchymal stem cells (WJCs) from human umbilical cord represent attractive and promising seeding cells in tissue regeneration and engineering for treatment applications. This study was carried out to explore the biocompatibility of scaffolds to seeding cells in vitro. Rod-like nano-hydroxyapatite (RN-HA) and flake-like micro-hydroxyapatite (FM-HA) coatings were prepared on Mg-Zn-Ca alloy substrates using micro-arc oxidation and electrochemical deposition. WJCs were utilized to investigate the cellular biocompatibility of Mg-Zn-Ca alloys after different surface modifications by observing the cell adhesion, morphology, proliferation, and osteoblastic differentiation. The in vitro results indicated that the RN-HA coating group was more suitable for cell proliferation and cell osteoblastic differentiation than the FM-HA group, demonstrating better biocompatibility. Our results suggested that the RN-HA coating on Mg-Zn-Ca alloy substrates might be of great potential in bone tissue engineering.