Copper-Cystine Biohybrid-Embedded Nanofiber Aerogels Show Antibacterial and Angiogenic Properties.

Copper-cystine-based high aspect ratio structures (CuHARS) possess exceptional physical and chemical properties and exhibit remarkable biodegradability in human physiological conditions. Extensive testing has confirmed the biocompatibility and biodegradability of CuHARS under diverse biological conditions, making them a viable source of essential Cu2+. These ions are vital for catalyzing the production of nitric oxide (NO) from the decomposition of S-nitrosothiols (RSNOs) found in human blood. The ability of CuHARS to act as a Cu2+ donor under specific concentrations has been demonstrated in this study, resulting in the generation of elevated levels of NO. Consequently, this dual function makes CuHARS effective as both a bactericidal agent and a promoter of angiogenesis. In vitro experiments have shown that CuHARS actively promotes the migration and formation of complete lumens by redirecting microvascular endothelial cells. To maximize the benefits of CuHARS, they have been incorporated into biomimetic electrospun poly(ε-caprolactone)/gelatin nanofiber aerogels. Through the regulated release of Cu2+ and NO production, these channeled aerogels not only provide antibacterial support but also promote angiogenesis. Taken together, the inclusion of CuHARS in biomimetic scaffolds could hold great promise in revolutionizing tissue regeneration and wound healing.

Nitric Oxide: Physiological Functions, Delivery, and Biomedical Applications.

Nitric oxide (NO) is a gaseous molecule that has a central role in signaling pathways involved in numerous physiological processes (e.g., vasodilation, neurotransmission, inflammation, apoptosis, and tumor growth). Due to its gaseous form, NO has a short half-life, and its physiology role is concentration dependent, often restricting its function to a target site. Providing NO from an external source is beneficial in promoting cellular functions and treatment of different pathological conditions. Hence, the multifaceted role of NO in physiology and pathology has garnered massive interest in developing strategies to deliver exogenous NO for the treatment of various regenerative and biomedical complexities. NO-releasing platforms or donors capable of delivering NO in a controlled and sustained manner to target tissues or organs have advanced in the past few decades. This review article discusses in detail the generation of NO via the enzymatic functions of NO synthase as well as from NO donors and the multiple biological and pathological processes that NO modulates. The methods for incorporating of NO donors into diverse biomaterials including physical, chemical, or supramolecular techniques are summarized. Then, these NO-releasing platforms are highlighted in terms of advancing treatment strategies for various medical problems.

Nanofiber capsules for minimally invasive sampling of biological specimens from gastrointestinal tract.

Accurate and rapid point-of-care tissue and microbiome sampling is critical for early detection of cancers and infectious diseases and often result in effective early intervention and prevention of disease spread. In particular, the low prevalence of Barrett's and gastric premalignancy in the Western world makes population-based endoscopic screening unfeasible and cost-ineffective. Herein, we report a method that may be useful for prescreening the general population in a minimally invasive way using a swallowable, re-expandable, ultra-absorbable, and retrievable nanofiber cuboid and sphere produced by electrospinning, gas-foaming, coating, and crosslinking. The water absorption capacity of the cuboid- and sphere-shaped nanofiber objects is shown ∼6000% and ∼2000% of their dry mass. In contrast, unexpanded semicircular and square nanofiber membranes showed <500% of their dry mass. Moreover, the swallowable sphere and cuboid were able to collect and release more bacteria, viruses, and cells/tissues from solutions as compared with unexpanded scaffolds. In addition to that, an expanded sphere shows higher cell collection capacity from the esophagus inner wall as compared with the unexpanded nanofiber membrane. Taken together, the nanofiber capsules developed in this study could provide a minimally invasive method of collecting biological samples from the duodenal, gastric, esophagus, and oropharyngeal sites, potentially leading to timely and accurate diagnosis of many diseases. STATEMENT OF SIGNIFICANCE: Recently, minimally invasive technologies have gained much attention in tissue engineering and disease diagnosis. In this study, we engineered a swallowable and retrievable electrospun nanofiber capsule serving as collection device to collect specimens from internal organs in a minimally invasive manner. The sample collection device could be an alternative endoscopy to collect the samples from internal organs like jejunum, stomach, esophagus, and oropharynx without any sedation. The newly engineered nanofiber capsule could be used to collect, bacteria, virus, fluids, and cells from the abovementioned internal organs. In addition, the biocompatible and biodegradable nanofiber capsule on a string could exhibit a great sample collection capacity for the primary screening of Barret Esophagus, acid reflux, SARS-COVID-19, Helicobacter pylori, and gastric cancer.

A new surgical method of treatment spontaneous intracranial hemorrhage.

OBJECTIVE: This study aimed to determine the safety and effectiveness of DTI-assisted neuroendoscopy for treating intracranial hemorrhage (ICH). METHODS: This retrospective study included clinical data from 260 patients with spontaneous supratentorial ICH who received neuroendoscopic hematoma removal. Patients were separated into groups based on the surgery method they received: DTI-assisted neuroendoscopy (69 cases) and standard neuroendoscopy (191 cases). All patients were followed up for 6 months. Multivariate logistic regression analyzed the risk factors affecting the prognosis of patients. The outcomes of the two groups were compared using Kaplan-Meier survival curves. RESULTS: The prognostic modified Rankin Scale (mRS) score was significantly better (P = 0.027) in the DTI-assisted neuroendoscopy group than in the standard neuroendoscopy group. Logistic regression analysis showed that DTI-assisted neuroendoscopy is an independent protective factor for a favorable outcome (model 1: odds ratio [OR] = 0.42, P = 0.015; model 2: OR = 0.40, P = 0.013). Kaplan-Meier survival curves were used to show that the median time for a favorable outcome was 66 days (95% confidence interval [CI] = 48.50-83.50 days) in the DTI-assisted neuroendoscopy group and 104 days (95% CI = 75.55-132.45 days) in the standard neuroendoscopy group. Log-rank testing showed that the DTI-assisted neuroendoscopy group had a lower pulmonary infection rate (χ 2 = 4.706, P = 0.030) and a better prognosis (χ 2 = 5.223, P = 0.022) than the standard neuroendoscopy group. The survival rate did not differ significantly between the DTI-assisted neuroendoscopy group and the standard neuroendoscopy group (P > 0.05). CONCLUSIONS: The use of DTI in neuroendoscopic hematoma removal can significantly improve neurological function outcomes in patients, but it does not significantly affect the mortality of patients.

Freeze-Casting with 3D-Printed Templates Creates Anisotropic Microchannels and Patterned Macrochannels within Biomimetic Nanofiber Aerogels for Rapid Cellular Infiltration.

A new approach is described for fabricating 3D poly(ε-caprolactone) (PCL)/gelatin (1:1) nanofiber aerogels with patterned macrochannels and anisotropic microchannels by freeze-casting with 3D-printed sacrificial templates. Single layer or multiple layers of macrochannels are formed through an inverse replica of 3D-printed templates. Aligned microchannels formed by partially anisotropic freezing act as interconnected pores between templated macrochannels. The resulting macro-/microchannels within nanofiber aerogels significantly increase preosteoblast infiltration in vitro. The conjugation of vascular endothelial growth factor (VEGF)-mimicking QK peptide to PCL/gelatin/gelatin methacryloyl (1:0.5:0.5) nanofiber aerogels with patterned macrochannels promotes the formation of a microvascular network of seeded human microvascular endothelial cells. Moreover, nanofiber aerogels with patterned macrochannels and anisotropic microchannels show significantly enhanced cellular infiltration rates and host tissue integration compared to aerogels without macrochannels following subcutaneous implantation in rats. Taken together, this novel class of nanofiber aerogels holds great potential in biomedical applications including tissue repair and regeneration, wound healing, and 3D tissue/disease modeling.

Minimally Invasive Delivery of 3D Shape Recoverable Constructs with Ordered Structures for Tissue Repair.

Minimally invasive procedures are becoming increasingly more common in surgery. However, the biomaterials capable of delivering biomimetic, three-dimensional (3D) functional tissues in a minimally invasive manner and exhibiting ordered structures after delivery are lacking. Herein, we reported the fabrication of gelatin methacryloyl (GelMA)-coated, 3D expanded nanofiber scaffolds, and their potential applications in minimally invasive delivery of 3D functional tissue constructs with ordered structures and clinically appropriate sizes (4 cm × 2 cm × 1.5 mm). GelMA-coated, expanded 3D nanofiber scaffolds produced by combining electrospinning, gas-foaming expansion, hydrogel coating, and cross-linking are extremely shape recoverable after release of compressive strain, displaying a superelastic property. Such scaffolds can be seeded with various types of cells, including dermal fibroblasts, bone marrow-derived mesenchymal stem cells, and human neural stem/precursor cells to form 3D complex tissue constructs. Importantly, the developed 3D tissue constructs can be compressed and loaded into a 4 mm diameter glass tube for minimally invasive delivery without compromising the cell viability. Taken together, the method developed in this study could hold great promise for transplantation of biomimetic, 3D functional tissue constructs with well-organized structures for tissue repair and regeneration using minimally invasive procedures like laparoscopy and thoracoscopy.

Tannic acid-inspired, self-healing, and dual stimuli responsive dynamic hydrogel with potent antibacterial and anti-oxidative properties.

Due to their intrinsic injectable and self-healing characteristics, dynamic hydrogels, based on dynamic covalent bonds, have gained a great attention. In this study, a novel dynamic hydrogel based on the boronic ester dynamic covalent bond is facilely developed using phenylboronic acid-modified hyaluronic acid (HA-PBA) and plant-derived polyphenol-tannic acid (TA). The dynamic hydrogel gelated quickly under mild conditions and had favorable viscoelastic properties with good self-healing and shear-thinning capabilities. Moreover, the simultaneous utilization of TA as a reductant for the green synthesis of silver nanoparticles (AgNP) inspired the preparation of a TA-reduced AgNP hybrid dynamic hydrogel with potent and broad-spectrum antibacterial activities. The dynamic hydrogels could also be applied for pH- and reactive oxygen species (ROS)-responsive release of loaded protein molecules without showing evident cytotoxicity and hemolysis in vitro. In addition, the dynamic hydrogels showed the anti-oxidative properties of high free radical and ROS scavenging capacity, which was verified by the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical assay and ROS fluorescence staining. Overall, this novel class of cytocompatible, self-healing, dual stimuli responsive, antibacterial, anti-oxidative, and injectable hydrogels could be promising as a wound dressing for chronic wound healing.

Kinesin Family Member C1 Increases Temozolomide Resistance of Glioblastoma Through Promoting DNA Damage Repair.

Glioblastoma (GBM) is one of the most frequent primary malignant brain tumors with a poor prognosis. Unfortunately, due to the intrinsic or acquired chemoresistance of GBM cells, it easily becomes refractory disease and tumors are easy to recur. Therefore, it is critical to elucidate the molecular mechanisms underlying the chemoresistance of GBM cells to discover more efficient therapeutic treatments. Kinesin family member C1 (KIFC1) is a normal nonessential kinesin motor that affects the progression of multiple types of cancers. However, whether KIFC1 have a function in GBM is still unexplored. Here we found that KIFC1 was upregulated in human temozolomide (TMZ)-resistant GBM tissues. KIFC1 silencing is sufficient to inhibit GBM cell proliferation and amplify TMZ-induced repression of cell proliferation. Mechanistically, KIFC1 silencing contributed to DNA damage, cell cycle arrest, and apoptosis through regulating Rad51, Akt, and DNA-PKcs phosphorylation. We also noticed that KIFC1 silencing also inhibited tumor formation and increased TMZ sensitivity through regulating Ki67, Rad51, γ-H2AX, and phosphorylation of AKT in vivo. Our findings therefore confirm the involvement of KIFC1 in GBM progression and provide a novel understanding of KIFC1-Akt axis in the sensitivity of GBM to chemotherapy.

Converting 2D Nanofiber Membranes to 3D Hierarchical Assemblies with Structural and Compositional Gradients Regulates Cell Behavior.

New methods are described for converting 2D electrospun nanofiber membranes to 3D hierarchical assemblies with structural and compositional gradients. Pore-size gradients are generated by tuning the expansion of 2D membranes in different layers with incorporation of various amounts of a surfactant during the gas-foaming process. The gradient in fiber organizations is formed by expanding 2D nanofiber membranes composed of multiple regions collected by varying rotating speeds of mandrel. A compositional gradient on 3D assemblies consisting of radially aligned nanofibers is prepared by dripping, diffusion, and crosslinking. Bone mesenchymal stem cells (BMSCs) on the 3D nanofiber assemblies with smaller pore size show significantly higher expression of hypoxia-related markers and enhanced chondrogenic differentiation compared to BMSCs cultured on the assemblies with larger pore size. The basic fibroblast growth factor gradient can accelerate fibroblast migration from the surrounding area to the center in an in vitro wound healing model. Taken together, 3D nanofiber assemblies with gradients in pore sizes, fiber organizations, and contents of signaling molecules can be used to engineer tissue constructs for tissue repair and build biomimetic disease models for studying disease biology and screening drugs, in particular, for interface tissue engineering and modeling.

Expanding sacrificially printed microfluidic channel-embedded paper devices for construction of volumetric tissue models in vitro.

We report a method for expanding microchannel-embedded paper devices using a precisely controlled gas-foaming technique for the generation of volumetric tissue models in vitro. We successfully fabricated hollow, perfusable microchannel patterns contained in a densely entangled network of bacterial cellulose nanofibrils using matrix-assisted sacrificial three-dimensional printing, and demonstrated the maintenance of their structural integrity after gas-foaming-enabled expansion in an aqueous solution of NaBH4. The resulting expanded microchannel-embedded paper devices showed multilayered laminar structures with controllable thicknesses as a function of both NaBH4 concentration and expansion time. With expansion, the thickness and porosity of the bacterial cellulose network were significantly increased. As such, cellular infiltration was promoted comparing to as-prepared, non-expanded devices. This simple technique enables the generation of truly volumetric, cost-effective human-based tissue models, such as vascularized tumor models, for potential applications in preclinical drug screening and personalized therapeutic selection.

Fast transformation of 2D nanofiber membranes into pre-molded 3D scaffolds with biomimetic and oriented porous structure for biomedical applications.

The ability to transform two-dimensional (2D) structures into three-dimensional (3D) structures leads to a variety of applications in fields such as soft electronics, soft robotics, and other biomedical-related fields. Previous reports have focused on using electrospun nanofibers due to their ability to mimic the extracellular matrix. These studies often lead to poor results due to the dense structures and small poor sizes of 2D nanofiber membranes. Using a unique method of combining innovative gas-foaming and molding technologies, we report the rapid transformation of 2D nanofiber membranes into predesigned 3D scaffolds with biomimetic and oriented porous structure. By adding a surfactant (pluronic F-127) to poly(ε-caprolactone) (PCL) nanofibers, the rate of expansion is dramatically enhanced due to the increase in hydrophilicity and subsequent gas bubble stability. Using this novel method together with molding, 3D objects with cylindrical, hollow cylindrical, cuboid, spherical, and irregular shapes are created. Interestingly, these 3D shapes exhibit anisotropy and consistent pore sizes throughout entire object. Through further treatment with gelatin, the scaffolds become superelastic and shape-recoverable. Additionally, gelatin-coated, cube-shaped scaffolds were further functionalized with polypyrrole coatings and exhibited dynamic electrical conductivity during cyclic compression. Cuboid-shaped scaffolds have been demonstrated to be effective for compressible hemorrhage in a porcine liver injury model. In addition, human neural progenitor cells can be uniformly distributed and differentiated into neurons throughout the cylinder-shaped nanofiber scaffolds, forming ordered 3D neural tissue constructs. Taken together, the approach presented in this study is very promising in the production of pre-molded 3D nanofiber scaffolds for many biomedical applications.

Mesenchymal stem cell-laden, personalized 3D scaffolds with controlled structure and fiber alignment promote diabetic wound healing.

The management of diabetic wounds remains a major therapeutic challenge in clinics. Herein, we report a personalized treatment using 3D scaffolds consisting of radially or vertically aligned nanofibers in combination with bone marrow mesenchymal stem cells (BMSCs). The 3D scaffolds have customizable sizes, depths, and shapes, enabling them to fit a variety of type 2 diabetic wounds. In addition, the 3D scaffolds are shape-recoverable in atmosphere and water following compression. The BMSCs-laden 3D scaffolds are capable of enhancing the formation of granulation tissue, promoting angiogenesis, and facilitating collagen deposition. Further, such scaffolds inhibit the formation of M1-type macrophages and the expression of pro-inflammatory cytokines IL-6 and TNF-α and promote the formation of M2-type macrophages and the expression of anti-inflammatory cytokines IL-4 and IL-10. Taken together, BMSCs-laden, 3D nanofiber scaffolds with controlled structure and alignment hold great promise for the treatment of diabetic wounds. STATEMENT OF SIGNIFICANCE: In this study, we developed 3D radially and vertically aligned nanofiber scaffolds to transplant bone marrow mesenchymal stem cells (BMSCs). We personalized 3D scaffolds that could completely match the size, depth, and shape of diabetic wounds. Moreover, both the radially and vertically aligned nanofiber scaffolds could completely recover their shape and maintain structural integrity after repeated loads with compressive stresses. Furthermore, the BMSCs-laden 3D scaffolds are able to promote granulation tissue formation, angiogenesis, and collagen deposition, and switch the immune responses to the pro-regenerative direction. These 3D scaffolds consisting of radially or vertically aligned nanofibers in combination with BMSCs offer a robust, customizable platform potentially for a significant improvement of managing diabetic wounds.

Faecal microbiota transplantation from metabolically compromised human donors accelerates osteoarthritis in mice.

OBJECTIVES: Emerging evidence suggests that the microbiome plays an important role in the pathogenesis of osteoarthritis (OA). We aimed to test the two-hit model of OA pathogenesis and potentiation in which one 'hit' is provided by an adverse gut microbiome that activates innate immunity; the other 'hit' is underlying joint damage. METHODS: Medical history, faecal and blood samples were collected from human healthy controls (OA-METS-, n=4), knee OA without metabolic syndrome (OA+METS-, n=7) and knee OA with metabolic syndrome (OA+METS+, n=9). Each group of human faecal samples, whose microbial composition was identified by 16S rRNA sequencing, was pooled and transplanted into germ-free mice 2 weeks prior to meniscal/ligamentous injury (MLI) (n≥6 per group). Eight weeks after MLI, mice were evaluated for histological OA severity and synovitis, systemic inflammation and gut permeability. RESULTS: Histological OA severity following MLI was minimal in germ-free mice. Compared with the other groups, transplantation with the OA+METS+ microbiome was associated with higher mean systemic concentrations of inflammatory biomarkers (interleukin-1ß, interleukin-6 and macrophage inflammatory protein-1α), higher gut permeability and worse OA severity. A greater abundance of Fusobacterium and Faecalibaterium and lesser abundance of Ruminococcaceae in transplanted mice were consistently correlated with OA severity and systemic biomarkers concentrations. CONCLUSION: The study clearly establishes a direct gut microbiome-OA connection that sets the stage for a new means of exploring OA pathogenesis and potentially new OA therapeutics. Alterations of Fusobacterium, Faecalibaterium and Ruminococcaceae suggest a role of these particular microbes in exacerbating OA.

Engineering Biomimetic Nanofiber Microspheres with Tailored Size, Predesigned Structure, and Desired Composition via Gas Bubble-Mediated Coaxial Electrospray.

Minimally invasive therapies avoiding surgical complexities evoke great interest in developing injectable biomedical devices. Herein, a versatile approach is reported for engineering injectable and biomimetic nanofiber microspheres (NMs) with tunable sizes, predesigned structures, and desired compositions via gas bubble-mediated coaxial electrospraying. The sizes and structures of NMs are controlled by adjusting processing parameters including air flow rate, applied voltage, distance, and spinneret configuration in the coaxial setup. Importantly, unlike the self-assembly method, this technique can be used to fabricate NMs from any material feasible for electrospinning or other nanofiber fabrication techniques. To demonstrate the versatility, open porous NMs are successfully fabricated that consist of various short nanofibers made of poly(ε-caprolactone), poly(lactic-co-glycolic acid), gelatin, methacrylated gelatin, bioglass, and magneto-responsive polymer composites. Open porous NMs support human neural progenitor cell growth in 3D with a larger number and more neurites than nonporous NMs. Additionally, highly open porous NMs show faster cell infiltration and host tissue integration than nonporous NMs after subcutaneous injection to rats. Such a novel class of NMs holds great potential for many biomedical applications such as tissue filling, cell and drug delivery, and minimally invasive tissue regeneration.

Complexation-induced resolution enhancement of 3D-printed hydrogel constructs.

Three-dimensional (3D) hydrogel printing enables production of volumetric architectures containing desired structures using programmed automation processes. Our study reports a unique method of resolution enhancement purely relying on post-printing treatment of hydrogel constructs. By immersing a 3D-printed patterned hydrogel consisting of a hydrophilic polyionic polymer network in a solution of polyions of the opposite net charge, shrinking can rapidly occur resulting in various degrees of reduced dimensions comparing to the original pattern. This phenomenon, caused by complex coacervation and water expulsion, enables us to reduce linear dimensions of printed constructs while maintaining cytocompatible conditions in a cell type-dependent manner. We anticipate our shrinking printing technology to find widespread applications in promoting the current 3D printing capacities for generating higher-resolution hydrogel-based structures without necessarily having to involve complex hardware upgrades or other printing parameter alterations.

Periosteum Mimetic Coating on Structural Bone Allografts via Electrospray Deposition Enhances Repair and Reconstruction of Segmental Defects.

Structural bone allograft transplantation remains one of the common strategies for repair and reconstruction of large bone defects. Due to the loss of periosteum that covers the outer surface of the cortical bone, the healing and incorporation of allografts is extremely slow and limited. To enhance the biological performance of allografts, herein, we report a novel and simple approach for engineering a periosteum mimetic coating on the surface of structural bone allografts via polymer-mediated electrospray deposition. This approach enables the coating on allografts with precisely controlled composition and thickness. In addition, the periosteum mimetic coating can be tailored to achieve desired drug release profiles by making use of an appropriate biodegradable polymer or polymer blend. The efficacy study in a murine segmental femoral bone defect model demonstrates that the allograft coating composed of poly(lactic-co-glycolic acid) and bone morphogenetic protein-2 mimicking peptide significantly improves allograft healing as evidenced by decreased fibrotic tissue formation, increased periosteal bone formation, and enhanced osseointegration. Taken together, this study provides a platform technology for engineering a periosteum mimetic coating which can greatly promote bone allograft healing. This technology could eventually result in an off-the-shelf and multifunctional structural bone allograft for highly effective repair and reconstruction of large segmental bone defects. The technology can also be used to ameliorate the performance of other medical implants by modifying their surfaces.

Dual Delivery of Alendronate and E7-BMP-2 Peptide via Calcium Chelation to Mineralized Nanofiber Fragments for Alveolar Bone Regeneration.

The fixation and stability of dental implants is governed by the quality of the underlying alveolar bone. The current study investigates if the dual delivery of calcium chelating bone therapeutics from mineralized nanofiber fragments can help regenerate alveolar bone in vivo. Alendronate (ALN) or/and bone morphogenetic protein-2-mimicking peptide conjugated to a heptaglutamate moiety (E7-BMP-2) were incorporated onto mineralized nanofiber fragments of polylactide-co-glycolide-collagen-gelatin (PCG in 2:1:1 weight ratios) via calcium coupling/chelation. Two mg of the single-loaded (ALN) and coloaded (ALN + E7-BMP-2) mineralized nanofiber PCG grafts was filled into critical-sized (2 mm diameter × 2 mm depth) alveolar bone defects in rat maxillae and let heal for 4 weeks. X-ray microcomputed tomography analysis of the retrieved maxillae revealed significantly elevated new bone formation parameters for the ALN and ALN + E7-BMP-2 groups compared with the unfilled defect controls. However, no significant differences between the single and coloaded nanofiber grafts were noted. Furthermore, the histopathological analysis of the tissue sections divulged islands of new bone tissue in the ALN and ALN + E7-BMP-2 groups, whereas the control defect was covered with gingival tissue. Together, the presented strategy using mineralized nanofiber fragments in the sustained delivery of dual calcium chelating therapeutics could have potential applications in enhancing bone regeneration.

A mouse model for vitamin D-induced human cathelicidin antimicrobial peptide gene expression.

In humans and other primates, 1,25(OH)2vitamin D3 regulates the expression of the cathelicidin antimicrobial peptide (CAMP) gene via toll-like receptor (TLR) signaling that activates the vitamin D pathway. Mice and other mammals lack the vitamin D response element (VDRE) in their CAMP promoters. To elucidate the biological importance of this pathway, we generated transgenic mice that carry a genomic DNA fragment encompassing the entire human CAMP gene and crossed them with Camp knockout (KO) mice. We observed expression of the human transgene in various tissues and innate immune cells. However, in mouse CAMP transgenic macrophages, TLR activation in the presence of 25(OH)D3 did not induce expression of either CAMP or CYP27B1 as would normally occur in human macrophages, reinforcing important species differences in the actions of vitamin D. Transgenic mice did show increased resistance to colonization by Salmonella typhimurium in the gut. Furthermore, the human CAMP gene restored wound healing in the skin of Camp KO mice. Topical application of 1,25(OH)2vitamin D3 to the skin of CAMP transgenic mice induced CAMP expression and increased killing of Staphylococcus aureus in a wound infection model. Our model can help elucidate the biological importance of the vitamin D-cathelicidin pathway in both pathogenic and non-pathogenic states.

Tethering peptides onto biomimetic and injectable nanofiber microspheres to direct cellular response.

Biomimetic and injectable nanofiber microspheres (NMs) could be ideal candidate for minimally invasive tissue repair. Herein, we report a facile approach to fabricate peptide-tethered NMs by combining electrospinning, electrospraying, and surface conjugation techniques. The composition and size of NMs can be tuned by varying the processing parameters during the fabrication. Further, bone morphogenic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) mimicking peptides have been successfully tethered onto poly(ε-caprolactone) (PCL):gelatin:(gelatin-methacryloyl) (GelMA)(1:0.5:0.5) NMs through photocrosslinking of the methacrylic group in GelMA and octenyl alanine (OCTAL) in the modified peptides. The BMP-2-OCTAL peptide-tethered NMs significantly promote osteogenic differentiation of bone marrow-derived stem cells (BMSCs). Moreover, human umbilical vein endothelial cells (HUVECs) seeded on VEGF mimicking peptide QK-OCTAL-tethered NMs significantly up-regulated vascular-specific proteins, leading to microvascularization. The strategy developed in this work holds great potential in developing a biomimetic and injectable carrier to efficiently direct cellular response (Osteogenesis and Angiogenesis) for tissue repair.