In-vivo evaluation of subcutaneously implanted cell-loaded apatite microcarriers for osteogenic potency.

Cell-loaded apatite microcarriers present as potential scaffolds for direct in-vivo delivery of cells post-expansion to promote bone regeneration. The objective of this study was to evaluate the osteogenic potency of human foetal mesenchymal stem cells (hfMSC)-loaded apatite microcarriers when implanted subcutaneously in a mouse model. This was done by examining for ectopic bone formation at 2 weeks, 1 month and 2 months, which were intended to coincide with the inflammation, healing and remodelling phases, respectively. Three histological examinations including haematoxylin and eosin staining to examine general tissue morphology, Masson's trichrome staining to identify tissue type, and Von Kossa staining to examine extent of tissue mineralisation were performed. In addition, immunohistochemistry assay of osteopontin was conducted to confirm active bone formation by the seeded hfMSCs. Results showed a high level of tissue organisation and new bone formation, with active bone remodelling being observed at the end of 2 months, and an increase in tissue density, organisation, and mineralisation could also be observed for hfMSC-loaded apatite microcarriers. Various cell morphology resembling that of osteoblasts and osteoclasts could be seen on the surfaces of the hfMSC-loaded apatite microcarriers, with presence of woven bone tissue formation being observed at the intergranular space. These observations were consistent with evidence of ectopic bone formation, which were absent in group containing apatite microcarriers only. Overall, results suggested that hfMSC-loaded apatite microcarriers retained their osteogenic potency after implantation, and provided an effective platform for bone tissue regeneration.

A multi-material coating containing chemically-modified apatites for combined enhanced bioactivity and reduced infection via a drop-on-demand micro-dispensing technique.

Prevention of infection and enhanced osseointegration are closely related, and required for a successful orthopaedic implant, which necessitate implant designs to consider both criteria in tandem. A multi-material coating containing 1:1 ratio of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite as the top functional layer, and hydroxyapatite as the base layer, was produced via the drop-on-demand micro-dispensing technique, as a strategic approach in the fight against infection along with the promotion of bone tissue regeneration. The homogeneous distribution of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets at alternate position in silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating delayed the exponential growth of Staphylococcus aureus for up to 24 h, and gave rise to up-regulated expression of alkaline phosphatase activity, type I collagen and osteocalcin as compared to hydroxyapatite and silver-substituted hydroxyapatite coatings. Despite containing reduced amounts of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets over the coated area than silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite coatings, silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating exhibited effective antibacterial property with enhanced bioactivity. By exhibiting good controllability of distributing silicon-substituted hydroxyapatite, silver-substituted hydroxyapatite and hydroxyapatite micro-droplets, it was demonstrated that drop-on-demand micro-dispensing technique was capable in harnessing the advantages of silver-substituted hydroxyapatite, silicon-substituted hydroxyapatite and hydroxyapatite to produce a multi-material coating along with enhanced bioactivity and reduced infection.

Mechanically-enhanced three-dimensional scaffold with anisotropic morphology for tendon regeneration.

Tissue engineering has showed promising results in restoring diseased tendon tissue functions. Herein, a hybrid three-dimensional (3D) porous scaffold comprising an outer portion rolled from an electrohydrodynamic jet printed poly(ɛ-caprolactone) (PCL) fiber mesh, and an inner portion fabricated from uniaxial stretching of a heat-sealed PCL tube, was developed for tendon tissue engineering (TE) application. The outer portion included three layers of micrometer-scale fibrous bundles (fiber diameter: ~25 µm), with an interconnected spacing and geometric anisotropy along the scaffold length. The inner portion showed orientated micro-ridges/grooves in a parallel direction to that of the outer portion. Owning to the addition of the inner portion, the as-fabricated scaffold exhibited comparable mechanical properties to those of the human patellar tendon in terms of Young's modulus (~227 MPa) and ultimate tensile stress (~50 MPa). Compared to the rolled electrospun fibers, human tenocytes cultured in the tendon scaffolds showed increased cellular metabolism. Furthermore, the 3D tendon scaffold resulted in up-regulated cell alignment, cell elongation and formation of collagen type I. These results demonstrated the potential of mechanically-enhanced 3D fibrous scaffold for applications in tendon TE, with desired cell alignment and functional differentiation.

Au-Fe3O4 nanozyme coupled with CRISPR-Cas12a for sensitive and visual antibiotic resistance diagnosing.

The accumulation and spread of antibiotic resistance bacteria (ARB) in the environment may accelerate the formation of superbugs and seriously threaten the health of all living beings. The timeliness and accurate diagnosing of antibiotic resistance is essential to controlling the propagation of superbugs in the environment and formulating effective public health management programs. Herein, we developed a speedy, sensitive, accurate, and user-friendly colorimetric assay for antibiotic resistance, via a synergistic combination of the peroxidase-like property of the Au-Fe3O4 nanozyme and the specific gene identification capability of the CRISPR-Cas12a. Once the CRISPR-Cas12a system recognizes a target resistance gene, it activates its trans-cleavage activity and subsequently releases the Au-Fe3O4 nanozymes, which oxidizes the 3,3,5,5-tetramethylbenzidine (TMB) with color change from transparent to blue. The diagnosing signals could be captured and analyzed by a smartphone. This method detected kanamycin-resistance genes, ampicillin-resistance genes, and chloramphenicol-resistance genes by simple operation steps with high sensitivity (<0.1 CFU µL-1) and speediness (<1 h). This approach may prove easy for the accurate and sensitive diagnosis of the ARGs or ARB in the field, thus surveilling and controlling the microbial water quality flexibly and efficiently.

Mechanically enhanced and osteobioactive synthetic periosteum via development of poly(ε-caprolactone)/microtantalum composite.

Periosteum, the thin layer covering adjacent to bone containing specific architecture, is important for functional bone regeneration and remodeling. Synthetic periosteum investigated presently lacks the resemblance of natural periosteum, suffering from poor mechanical strength and cell attachment. Here, we report a newly-developed biomimetic film to function as synthetic periosteum. Based on poly(ε-caprolactone) (PCL), where surface wettability of the synthetic periosteum is enhanced by microtantalum (mTa) particle blending and after a cold drawing process, further obtains topographical anisotropy without any involvement of solvent. This new blend shows mechanical enhancement over pure PCL, with yield stress and elastic strain approaching the natural periosteum. A distinct degradation mechanism is proposed for the blend, and by seeding with mouse calvarial preosteoblasts, cell proliferation is promoted on surface of the drawn PCL but delayed on the mTa-blended PCL. However, cell mineralization is accelerated on the mTa-blended surface. This is less on the drawn PCL. The synergistical integration of cellular proliferation, alignment and osteogenic enhancement suggest that the cold drawn PCL/Ta blend has unique potential for developing into a synthetic periosteum and other tissue-engineering products.

Scaffold Engineering with Flavone-Modified Biomimetic Architecture for Vascular Tissue Engineering Applications.

BACKGROUND: Vascular intimal hyperplasia (IH) is one of the key challenges in the clinical application of small-diameter vascular grafts. Current tissue engineering strategies focus on vascularization and antithrombotics, yet few approaches have been developed to treat IH. Here, we designed a tissue-engineered vascular scaffold with portulaca flavonoid (PTF) composition and biomimetic architecture. METHOD: By electrospinning, PTF is integrated with biodegradable poly(ε-caprolactone) (PCL) into a bionic vascular scaffold. The structure and functions of the scaffolds were evaluated based on material characterization and cellular biocompatibility. Human vascular smooth muscle cells (HVSMCs) were cultured on scaffolds for up to 14 days. RESULTS: The incorporation of PTF and preparation parameters during fabrication influences the morphology of the scaffold, including fibre diameter, structure, and orientation. Compared to the PCL scaffold, the scaffolds integrated with bioactive PTF show better hydrophilicity and degradability. HVSMCs seeded on the scaffold alongside the fibres exhibit fusiform-like shapes, indicating that the scaffold can provide contact guidance for cell morphology alterations. This study demonstrates that the PCL/PTF (9.1%) scaffold inhibits the excessive proliferation of HVSMCs without causing cytotoxicity. CONCLUSION: The study provides insights into the problem of restenosis caused by IH. This engineered vascular scaffold with complex function and preparation is expected to be applied as a substitute for small-diameter vascular grafts.

Effects of integrated bioceramic and uniaxial drawing on mechanically-enhanced fibrogenesis for bionic periosteum engineering.

Periosteum is clinically required for the management of large bone defects. Attempts to exploit the periosteum's participation in bone healing, however, have rarely featured biological and mechanical complexity for the scaffolds relevant to translational medicine. In this regard, we report engineering of bioinspired periosteum with co-delivery of ionic and geometry cues. The scaffold demonstrated microsheet-like fibre morphology and was developed based on bioresorbable poly(-caprolactone) and bioactive copper-doped tricalcium phosphate (Cu-TCP). A coordinated interaction was found between the effects of Cu-TCP addition and uniaxial drawing, leading to tunable fibrogenesis for different fibre morphologies, organisation, and surface wettability. The coordination resulted in significant enhancements in Young's Modulus, yield stress and ultimate stress along fibrous alignment, without causing reductions across fibres. This demonstrated mechanical anisotropy of the scaffold similar to natural periosteum, and seeding with mouse calvarial preosteoblasts, the scaffold supported cell alignment with deposition of CaP-like nodules and extracellular matrix. This work provides new insights on periosteum engineering with osteo-related composite fibres. The artificial periosteum can be used in clinical settings to facilitate repair of large bone defects.

The significance of thermomechanical processing on the cellular response of biomedical Co-Cr-Mo alloys.

Strengthening of biomedical Co-Cr-Mo alloys has been explored via thermomechanical processing for enhancing the durability of their biomedical applications. However, the effects of cold and hot deformation on the cellular activity continue to be unclear. In this study, we prepared Co-Cr-Mo alloy rods via cold swaging and hot-caliber rolling and studied the relationship between the microstructure and cellular response of pre-osteoblasts. The cold-swaged rod experienced strain-induced martensitic transformation, which increased the volume fraction of the hexagonal close-packed (hcp) ε-martensite to ∼60 vol.% with an increase in area reduction (r) to 30%. The 111γ fiber texture of the face-centered cubic (fcc) γ-matrix followed the Shoji-Nishiyama orientation relationship with ε-martensite. Cell culture results revealed beneficial effects of cold swaging on the cell response, in terms of adhesion, proliferation and morphology of cells, although increasing r did not significantly affect cellular metabolism levels. The addition of small content of Zr (0.04 wt.%) led to enhanced focal adhesion of cells, which became more significant at higher r. The microstructural evolution during hot-caliber rolling, namely, grain refinement without any phase transformation and strong texture development, did not appreciably affect the cellular activity. These findings are envisaged to facilitate alloy design and microstructural optimization for favorable tuning the osseointegration of biomedical Co-Cr-Mo alloys.

Clinical perspectives for repairing rotator cuff injuries with multi-tissue regenerative approaches.

Background: In the musculoskeletal system, bone, tendon, and muscle form highly integrated multi-tissue units such as the rotator cuff complex, which facilitates functional and dynamic movement of the shoulder joint. Understanding the intricate interplay among these tissues within clinical, biological, and engineering contexts is vital for addressing challenging issues in treatment of musculoskeletal disorders and injuries. Methods: A wide-ranging literature search was performed, and findings related to the socioeconomic impact of rotator cuff tears, the structure-function relationship of rotator cuff bone-tendon-muscle units, pathophysiology of injury, current clinical treatments, recent state-of-the-art advances (stem cells, growth factors, and exosomes) as well as their regulatory approval, and future strategies aimed at engineering bone-tendon-muscle musculoskeletal units are outlined. Results: Rotator cuff injuries are a significant socioeconomic burden on numerous healthcare systems that may be addressed by treating the rotator cuff as a single complex, given its highly integrated structure-function relationship as well as degenerative pathophysiology and limited healing in bone-tendon-muscle musculoskeletal tissues. Current clinical practices for treating rotator cuff injuries, including the use of commercially available devices and evolving trends in surgical management have benefited patients while advances in application of stem/progenitor cells, growth factors, and exosomes hold clinical potential. However, such efforts do not emphasize targeted regeneration of bone-tendon-muscle units. Strategies aimed at regenerating bone-tendon-muscle units are thus expected to address challenging issues in rotator cuff repair. Conclusions: The rotator cuff is a highly integrated complex of bone-tendon-muscle units that when injured, has severe consequences for patients and healthcare systems. State-of-the-art clinical treatment as well as recent advances have resulted in improved patient outcome and may be further enhanced by engineering bone-tendon-muscle multi-tissue grafts as a potential strategy for rotator cuff injuries. Translational Potential of this Article: This review aims to bridge clinical, tissue engineering, and biological aspects of rotator cuff repair and propose a novel therapeutic strategy by targeted regeneration of multi-tissue units. The presentation of these wide-ranging and multi-disciplinary concepts are broadly applicable to regenerative medicine applications for musculoskeletal and non-musculoskeletal tissues.

Surface Design for Antibacterial Materials: From Fundamentals to Advanced Strategies.

Healthcare-acquired infections as well as increasing antimicrobial resistance have become an urgent global challenge, thus smart alternative solutions are needed to tackle bacterial infections. Antibacterial materials in biomedical applications and hospital hygiene have attracted great interest, in particular, the emergence of surface design strategies offer an effective alternative to antibiotics, thereby preventing the possible development of bacterial resistance. In this review, recent progress on advanced surface modifications to prevent bacterial infections are addressed comprehensively, starting with the key factors against bacterial adhesion, followed by varying strategies that can inhibit biofilm formation effectively. Furthermore, "super antibacterial systems" through pre-treatment defense and targeted bactericidal system, are proposed with increasing evidence of clinical potential. Finally, the advantages and future challenges of surface strategies to resist healthcare-associated infections are discussed, with promising prospects of developing novel antimicrobial materials.

Silver, silicon co-substituted hydroxyapatite modulates bacteria-cell competition for enhanced osteogenic function.

Combating bacteria while promoting tissue regeneration is an aim of highest priority for employing biomaterials in orthopedics that often embroiled with pre-operative contamination. Through simulating a surgical site infection environment and an infected implant site, we showcase the ability of a functionally modified hydroxyapatite, Ag,Si-HA that permits preferential adhesion of human bone marrow derived mesenchymal stem cells (BMSCs) over co-cultured bacterial pathogen,Pseudomonas aeruginosa, by displaying immediate suppression and killing of the bacteria present with minimum cytotoxicity for 28 d. And, at the same time, Ag,Si-HA stimulates BMSCs towards osteogenic differentiation despite being within the contaminated milieu. These findings provide well-defined requirements for incorporating antibacterial properties to biomaterials in managing pre-operative contamination. In addition, it highlights the dual positive attributes of Ag,Si-HA as an effective antibacterial biomaterial and at the same time, promotes bone tissue regeneration.

Study of interfacial random strain fields in core-shell ZnO nanowires by scanning transmission electron microscopy.

Imaging strain fields at the nanoscale is crucial for understanding the physical properties as well as the performance of oxide heterostructures and electronic devices. Based on scanning transmission electron microscopy (STEM) techniques, we successfully imaged the random strain field at the interface of core-shell ZnO nanowires. Combining experimental observations and image simulations, we find that the strain contrast originates from dechanneling of electrons and increased diffuse scattering induced by static atomic displacements. For a thin sample with a random strain field, a positive strain contrast appears in the low-angle annular dark-field (LAADF) image and a negative contrast in the high-angle annular dark-field (HAADF) image, but for a thick sample (> 120 nm), the positive contrast always occurs in both the LAADF and HAADF images. Through the analysis of the relationship between strain contrast and various parameters, we also discuss the optimum experimental condition for imaging random strain fields.

Silicon-incorporated nanohydroxyapatite-reinforced poly(ε-caprolactone) film to enhance osteogenesis for bone tissue engineering applications.

Biomaterials composed of polymers and bioceramics have great prospects to repair large and complicated bone defects. Here, we developed a composite film consisting of poly(ε-caprolactone) (PCL) and silicon-substituted hydroxyapatite (Si-HA) nanoparticles to enhance the osteogenic effects of the scaffold for bone tissue engineering applications. The results showed that the Si-HA nanoparticles obtained an even distribution in the PCL matrix, resulting in a homogeneous composite film. Compared to HA-incorporated PCL film, the addition of silicon did not cause hydrophilic alterations to the film surface. With the seeding of mouse calvarial preosteoblasts (MC3T3-E1), the cells exhibited the good behaviors of adhesion and growth on the PCL/Si-HA film. Compared to the PCL/HA films, incorporation of Si-HA nanoparticles in PCL/Si-HA films showed the increased production of alkaline phosphatase (ALP) and calcium content by MC3T3-E1 cells. These results suggested the suitability of the PCL/Si-HA composite film to elicit cellular growth and functional differentiation with the potential for bone tissue engineering applications.

A multi-layered composite assembly of Bi nanospheres anchored on nitrogen-doped carbon nanosheets for ultrastable sodium storage.

Bismuth (Bi) is a promising anode candidate for sodium ion batteries (SIBs) with a high volumetric capacity (3765 mA h cm-3) and moderate working potential but suffers from large volume change (ca. 250%) during the sodiation/desodiation process, resulting in pulverization of the electrode, electrical contact loss, excessive accumulation of solid electrolyte interfaces, etc., devastating the cycling stability of the electrode seriously. Addressing this issue significantly relies on rational micro- and nano-structuring. Herein, we prepared a 3D multi-layered composite assembly of Bi/carbon heterojunctions with 0D bismuth nanospheres distributed and anchored on 2D nitrogen-doped carbon nanosheets (NCSs), using a preorganization strategy by taking full advantage of the strong complexation ability of Bi3+. The multi-layered composite assembly is periodic and close-packed, with Bi nanospheres <25 nm, carbon nanosheets ∼30 nm, and an average interlayer space of ∼75 nm. Such a specific architecture provides abundant electrochemically active surfaces and ion migration channels as the Bi nanospheres are attached to the 2D nitrogen-doped carbon nanosheets via a point-to-surface pattern. Moreover, the mono-layer Bi nanospheres oriented along the 2D-surface of NCSs are kinetically favorable for the recognition of Na+ by the active sites of Bi nanospheres as well as for avoiding the long distance migration of Na+ (external diffusion of Na+). Furthermore, thermodynamically, the small size and high surface energy of ultrasmall Bi nanospheres could contribute to high ion mobility (internal diffusion of Na+) and promote electrochemical reactions as well. The multi-layered composite assembly of Bi@NCSs (ML-Bi@NCSs) not only provides a robust 3D framework guaranteeing the whole structural stability but also ensures direct and full contact of each active nano-building block with electrolyte, thereby forming a high-throughput electron/ion transport system. When evaluated as the anode for SIBs, ML-Bi@NCSs deliver superior high-rate capability up to 30 A g-1 (specific capacity: 288 mA h g-1) and long-term cycling stability (capacity retention: 95.8% after 5000 cycles at 10 A g-1 and 90.6% after 10 000 cycles at 20 A g-1, respectively).

Cellular uptake mechanism of molecular umbrella.

Molecular umbrella provided a promising avenue for the design of the intracellular delivery of hydrophilic therapeutic agents. However, the limited understanding of its cellular uptake would be a roadblock to its effective application. Herein, we investigate the ability and mechanism of cellular entry of a fluorescently labeled diwalled molecular umbrella, which was synthesized from cholic acid, spermine, and 5-carboxyfluorescein, into Hela cells, with the extent of uptake analyzed by confocal fluorescence microscopy and flow cytometry. It is found that the as-synthesized diwalled molecular umbrella can greatly facilitate cellular uptake of hydrophilic agent, 5-carboxyfluorescein. In vitro experiments with diffuse marker, endocytic marker, and inhibitors suggested that several distinct uptake pathways (e.g., passive diffuse, clathrin-mediated endocytosis, and caveolae/lipid-raft-dependent endocytosis) are involved in the internalization of diwalled molecular umbrella. These results, together with its low toxicity and good biocompatibility, thus demonstrate the suitability of molecular umbrella for application as vectors in drug delivery systems.

Scaffold with Micro/Macro-Architecture for Myocardial Alignment Engineering into Complex 3D Cell Patterns.

Tissue structural anisotropy is an important basis for heart function. Attempts to regenerate the complicated heart-tissue alignment has rarely featured macroscale 3D constructs required for myocardial tissue engineering. The feasibility of engineered scaffolds with micro/macro-architecture for guiding spatial cell alignment following complex patterns is reported. The scaffold is composed of stackable dual-structured layers with linear micro-ridge/groove patterns and macro-through-hole arrays, which enable tailorable anisotropy and interconnective free space. When human mesenchymal stem cells are seeded on the scaffold, well-organized spreading alignment showing the precise control in cellular orientation is significantly introduced over nonpatterned controls. Moreover, spatial cell distribution in the scaffold and directional changes of the layered linear patterns that made cell alignment orientations turning accordingly are observed, leading to the complex 3D pattern reconstruction of cellular alignment resembling natural myocardial tissue. This work validates the potential of micro/macro-architecture engineering for spatial cell guidance. Scaffolds with this capability can be potentially used for biomanufacturing of the structural alignment in myocardial tissue engineering.

Beta-cyclodextrin modified mesoporous bioactive glass nanoparticles/silk fibroin hybrid nanofibers as an implantable estradiol delivery system for the potential treatment of osteoporosis.

Osteoporosis, a systemic skeletal disease prevalent in elderly women, is associated with post-menopausal estrogen deficiency. Although systemic administration of exogenous estradiol (E2) reduced fragility fractures, the treatment has adverse effects. Localized delivery technologies of E2 could be utilized to circumvent the systemic adverse effects of systemic administration. In this study, a localized E2 delivery system is developed. Mesoporous bioactive glass nanoparticles (MBGNPs) with inherent osteogenic properties are modified with ß-cyclodextrin (CD-MBGNPs) to enhance their affinity for E2. To ensure mechanical stability and integrity, E2 loaded CD-MBGNPs are further electrospun with silk fibroin (SF) to produce a nanofibrous mesh (E2@CD-MBGNPs/SF). The incorporation of MBGNPs in SF enhances in vitro apatite formation and sustains the constant release of E2. Moreover, osteoblast proliferation and differentiation markers such as alkaline phosphatase activity, collagen 1 and osteocalcin expression of MC3T3-E1 are augmented in CD-MBGNPs/SF and E2@CD-MBGNPs/SF as compared to SF nanofibers. On the other hand, osteoclast DNA, tartrate resistant acid phosphatase activity and multinucleated cell formation are reduced in E2@CD-MBGNPs/SF as compared to CD-MBGNPs/SF and SF. Hence the presence of CD-MBGNPs in SF stimulates osteoblast function whereas E2 incorporation in CD-MBGNPs/SF reduces osteoclast activity. This is the first report to develop CD-MBGNPs/SF as a localized delivery system for hydrophobic molecules such as estradiol to treat osteoporosis.

Reliable laser fabrication: the quest for responsive biomaterials surface.

Laser techniques have been traditionally used for material processing. Currently, there is growing recognition that lasers are a reliable fabrication tool that can be used to tailor the surfaces of biomaterials for tissue-engineering applications. Herein, we review the use of selected lasers with a wide range of wavelengths and pulses. We present typical examples to illustrate the basic fabrication principles and significance of laser fabrication in tailoring biomaterial surfaces with different geometric features. We also discuss the tissue-engineering applications of laser-fabricated biomaterials; these biomaterial surfaces show promise in delivering physicochemical cues for hard and soft tissue reconstruction.

Estradiol-Loaded Poly(ε-caprolactone)/Silk Fibroin Electrospun Microfibers Decrease Osteoclast Activity and Retain Osteoblast Function.

Estrogen, a steroid hormone, plays an important role in modulating osteoclast proliferation and development. Estrogen deficiency boosts osteoclast activity, leading to osteoporosis in elderly women. In this study, 17-ß estradiol (E2)-loaded poly(ε-caprolactone) (PCL)/silk fibroin (SF) electrospun microfibers were developed as a proposed localized E2 delivery system to treat osteoporotic fractures. PCL is a synthetic polymer known for its biocompatibility and excellent mechanical properties. The bioactivity of PCL was enhanced by mixing it with a natural SF polymer that has low immunogenicity and inherent bioactivity. Different ratios of PCL/SF blends were electrospun and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and water contact angle measurement. PCL and SF at a ratio of 50:50 (PCL50/SF50) augmented cell proliferation of murine preosteoblast MC3T3-E1 cells and murine preosteoclast RAW 264.7 cells. Hence, PCL50/SF50 was selected and mixed with three concentrations of E2 to produce electrospun fiber mesh (0.1% E2@PCL/SF, 1% E2@PCL/SF, and 5% E2@PCL/SF). Sustained release of E2 was obtained for about 3 weeks at higher E2 concentration 5% E2@PCL/SF. An E2-loaded PCL50/SF50 elecrospun microfiber (1% E2@PCL/SF and 5% E2@PCL/SF) reduced tartrate-resistant acid phosphate activity, total DNA, and multinucleated cell formation of osteoclasts. On the other hand, the alkaline phosphatase activity and collagen I expression of osteoblasts were retained on all E2-loaded electrospun microfibers. The E2@PCL/SF system shows potential to be used for localized E2 delivery for the treatment of osteoporotic fractures.

Uniformly-dispersed nanohydroxapatite-reinforced poly(ε-caprolactone) composite films for tendon tissue engineering application.

Regeneration of injuries at tendon-to-bone interface (TBI) remains a challenging issue due to the complex tissue composition involving both soft tendon tissues and relatively hard bone tissues. Tissue engineering using polymeric/ceramic composites has been of great interest to generate scaffolds for tissue's healing at TBI. Herein, we presented a novel method to blend polymers and bioceramics for tendon tissue engineering application. A homogeneous composite comprising of nanohydroxyapatite (nHA) particles in poly(ε-caprolactone) (PCL) matrix was obtained using a combination of solvent and mechanical blending process. X-ray diffraction analysis showed that the as-fabricated PCL/nHA composite film retained phase-pure apatite and semi-crystalline properties of PCL. Infrared spectroscopy spectra confirmed that the PCL/nHA composite film exhibited the characteristics functional groups of PCL and nHA, without alteration to the chemical properties of the composite. The incorporation of nHA resulted in PCL/nHA composite film with improved mechanical properties such as Young's Modulus and ultimate tensile stress, which were comparable to that of the native human rotator tendon. Seeding with human tenocytes, cells attached on the PCL/nHA composite film, and after 14days of culturing, these cells could acquire elongated morphology without induced cytotoxicity. PCL/nHA composite film could also result in increased cell metabolism with prolonged culturing, which was comparable to that of the PCL group and higher than that of the nHA group. All these results demonstrated that the developed technique of combining solvent and mechanical blending could be applied to fabricate composite films with potential for tendon tissue engineering applications.