Biomedical Materials

Published by IOP Publishing
Online ISSN: 1748-605X
Print ISSN: 1748-6041
Discipline: Engineering, Biomedical Materials Science, Biomaterials
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Aims and scope

Biomedical Materials publishes original research findings and critical reviews that contribute to our knowledge about the composition, properties, and performance of materials for all applications relevant to human healthcare.

Recent publications
Illustration of biosynsphere fabrication and characteristics. (a) Conceptual illustration of the structure of a biosynsphere. (b) Schematic illustration of the biosynsphere fabrication process. Scale bar: bottom-left, 500 μm; bottom-right, 200 μm. (c) Biosynsphere size distribution of three parallel batches with target average size of 300 μm. (d) Microscopic images of biosynspheres with different diameters and cell densities. Scale bar: 100 μm. (e) Schematic illustration of biosynsphere post-fabrication processing.
The cellular functions (activities) of ADSCs in the form of biosynspheres. Different markers were used to reveal the properties of encapsulated ADSCs including (a) viability, (b) and (c) stemness, (d) differentiation, (e) attachment and stretching, (f) proliferation, (g) migration, (h) cell–cell connection, (i) fusion of biosynspheres. Thin and thick white arrows indicate cells observed to migrate at 0, 2, and 4 h.
The status of biosynspheres and typical cellular behaviors of encapsulated ADSCs before and after cryopreservation and thawing. (a) and (b) Appearance and measured diameter of biosynspheres before and after cryopreservation and thawing. Scale bar: 200 μm. (c) Fluorescent images of cell live/dead staining before and after cryopreservation and thawing. Scale bar: 200 μm. (d) Cell surface marker expression before and after cryopreservation and recovery. (e) Cell proliferation before and after cryopreservation and thawing. (f)–(h) Induced osteogenic (f), adipogenic (g), and chondrogenic (h) differentiation of encapsulated ADSCs within the cryopreserved biosynspheres.
The improvement of wound healing on the swine full skin defect model with the use of biosynspheres. (a) Top left graphic illustration of experimental setup. Top right: Records of wound closure from day 0 to day 42. Bottom: Morphological records showing wound healing process from day 0 to day 42. Red rectangular on day 42 images indicate the histological sampling area. (b) Top: Representative Masson stained cross-sections of the healed wounds on day 42. Dotted lines represent the boundary of the scar tissues and the regenerated tissue. R and S indicate the regenerated tissue and the scar tissue, respectively. Bottom: Fibrosis area and epithelization rate calculated from Masson stained samples. (c) Top: Polarizing microscopic images indicating the transition region from the regenerative tissue to the scar tissue of the healed wounds on day 42. Bottom: Analysed results of the polarizing microscopic images in terms of the deposition of collagen type I and type III.
Cell encapsulation has proven to be promising in stem cell therapy. However, there are issues needed to be addressed, including unsatisfied yield, unmet clinically friendly formulation, and unacceptable viability of stem cells after cryopreservation and thawing. We developed a novel biosynsphere technology to encapsulate stem cells in clinically-ready biomaterials with controlled microsphere size. We demonstrated that biosynspheres ensure the bioviability and functionality of adipose-derived stromal cells (ADSCs) encapsulated, as delineated by a series of testing procedures. We further demonstrated that biosynspheres protect ADSCs from the hardness of clinically handling such as cryopreservation, thawing, high-speed centrifugation and syringe/nozzle injection. In a swine full skin defect model, we showed that biosynspheres were integrated to the destined tissues and promoted the repair of injured tissues with an accelerating healing process, less scar tissue formation and normalized deposition of collagen type I and type III, the ratio similar to that found in normal skin. These findings underscore the potential of biosynsphere as an improved biofabrication technology for tissue regeneration in clinical setting.
It is well established that surface topography can affect cell functions. However, finding a reproducible and reliable method for regulating stem cell behavior is still under investigation. It has been shown that cell imprinted substrates contain micro- and nanoscale structures of the cell membrane that serve as hierarchical substrates, can successfully alter stem cell fate. This study investigated the effect of the overall cell shape by fabricating silicon wafers containing pit structure in the average size of spherical-like chondrocytes using photolithography technique. We also used chondrocyte cell line (C28/I2) with spindle-like shape to produce cell imprinted substrates. The effect of all substrates on the differentiation of adipose-derived mesenchymal stem cells (ADSCs) has been studied. The AFM and SEM images of the prepared substrates demonstrated that the desired shapes were successfully transferred to the substrates. Differentiation of ADSCs was investigated by immunostaining for mature chondrocyte marker, collagen II, and gene expression of collagen II, Sox9, and aggrecan markers. C28/I2 imprinted substrate could effectively enhanced chondrogenic differentiation compared to regular pit patterns on the wafer. It can be concluded that cell imprinted substrates can induce differentiation signals better than engineered lithographic substrates. The nanostructures on the cell-imprinted patterns play a crucial role in harnessing cell fate. Therefore, the patterns must include the nano-topographies to have reliable and reproducible engineered substrates.
Background: Sericin and egg white (EW) have shown the ability to promote wound healing. However, there have been insufficient studies regarding the effects of sericin and EW mixtures on wound healing. This study aimed to investigate the effects of a hybrid sericin and EW solution on wound repair and inflammation-related indicators in mouse skin. Methods: In this work, sericin with a low molecular weight was first mixed with homogeneous EW to prepare a hybrid wound dressing. Histology evaluation, the expression of C-reactive protein (CRP) and inflammatory cytokines in mice were tested to determine the effects of this dressing on skin injuries in mice. Results: The results showed that sericin and the hybrid solution of sericin and EW effectively promoted wound healing in mouse skin. The wound recovery rates of mice 12 days after treatment with a medium dose of sericin (0.2 g/mL) and the same dosage of sericin with added EW were 1.32 and 1.65 times that of mice treated with phosphate buffer saline (PBS) as a control, respectively. In addition, the mixture solution was more effective in wound healing than sericin alone. Sericin with EW significantly reduced the expression of CRP and inflammatory cytokines in mice during wound healing. Conclusion: A sericin and EW hybrid solution can effectively shorten the time needed for wound healing and reduce inflammation-related indicators in mice, making it a promising candidate for wound dressing.
Bone implants fabricated using nanocomposites containing hydroxyapatite and barium titanate showed piezoelectricity, osteoconductive, osteoinductive, and osteointegration properties for bone regeneration applications. In our present study, hydroxyapatite (HA) and barium titanate (BT) nanopowders were synthesized using high-energy ball-milling (HEBM)-assisted solid-state reaction with precursors of calcium carbonate and ammonium dihydrogen phosphate, and barium carbonate and titanium oxide powder mixtures, respectively. Hexagonal HA and tetragonal BT phases were formed after calcination at 700 and 1000 °C, respectively. Subsequently, HA/BT nanocomposites with different weight percentages of HA and BT were prepared by ball-milling, then compacted and sintered at two different temperatures to endow these bioceramics with better mechanical, dielectric, and biological properties for bone regeneration. Microstructure, crystal phases, and molecular structure characterizations of these sintered HA/BT nanocomposite compacts (SHBNCs) were performed using field-emission scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. Bulk density was evaluated using the Archimedes method. HA/BT nanocomposites with increased BT content showed enhanced dielectric properties, and the dielectric constant (εr) value for 5HA/95BT was ~182 at 100 Hz. Mechanical properties such as Vicker's hardness, fracture toughness, yield strength, and diametral tensile strength were also investigated. The hemolysis assay of SHBNCs exhibited hemocompatibility. The effect of these SHBNCs as implants on the in vitro cytocompatibility and cell viability of MG-63 osteoblast-like cells was assessed by MTT assay and live/dead staining, respectively. 15HA/85BT showed increased metabolic activity with a higher number of live cells than BT after the culture period. Overall, the sintered HA/BT nanocomposite compacts can be used as orthopedic implants for bone regeneration applications.
Characterization of composition in native and decellularized precision-cut kidney slices (PCKS) for removal of DNA and retention of glycosaminoglycans (GAGs) and collagen. PCKS were decellularized by immersion in chemicals (CHEM) or in combination with high hydrostatic pressure (HHP), freezing–thawing cycles (FTC) or ultrasonic bath system (UBS). (A) DNA quantification shows that freezing-thawing-cycles (FTC) achieved the highest reduction when compared to native PCKS and a significant difference compared to CHEM. (B) Quantification of GAGs reveals a significant reduction by all methods compared to the native PCKS, while FTC achieved a similar amount to CHEM. (C) Collagen content was generally preserved in scaffolds by all methods whereas HHP 200 resulted in a significant reduction compared to native PCKS. The specific amounts are given as the ratio of the target substance (ng) to the dry weight of the sample (mg). Data were analyzed with Mann–Whitney U test and values are expressed as mean ± SD (n ⩾ 3). Significant differences are indicated by (*p ⩽ 0.05), (**p ⩽ 0.01) and (***p ⩽ 0.001).
Histological analysis with hematoxylin and eosin (H&E) and evaluation with the scoring system for native and precision-cut kidney slices (PCKS) decellularized by immersion in chemicals (CHEM) or in combination with high hydrostatic pressure (HHP), freezing-thawing cycles (FTC) or ultrasonic bath system (UBS). Representative images of native kidney tissue (A) and decellularized PCKS (B-H), showing a general preservation and no complete breakdown of glomerular and tubular structures. Arrows point at remaining nuclear (hematoxylin, blue arrow) and cytoplasmic material (eosin, black arrow). (B) CHEM, (C) HHP 50, (D) HHP 100 and (E) HHP 200 show no remaining individual cell nuclei whereas the positive hematoxylin and eosin staining in some regions indicate non-effective removal of nuclear and cytoplasmic material respectively. (F) UBS 30, (G) UBS 60 and (H) FTC demonstrate full removal of cell nuclei and show no remaining hematoxylin as well as much better removal of cytoplasmic material. All images were presented using a 20× objective and a scale bar of 100 μm. For better visibility of the structures, the contrast of the images was slightly enhanced with ImageJ (I) corresponding histology scores demonstrating a statistically significant difference for CHEM and FTC scaffolds. Groups were compared with Kruskal–Wallis test followed by a pairwise analysis with Dunn’s test. Values are expressed as mean ± SD (n ⩾ 4). Significant differences are indicated by (**p ⩽ 0.01).
Scanning electron microscopy of the ultrastructure of native and precision-cut kidney slices (PCKS) decellularized by immersion in chemicals (CHEM) or in combination with high hydrostatic pressure (HHP), freezing-thawing cycles (FTC) or ultrasonic bath system (UBS). Representative images are divided into three columns at different magnifications: (A) 500×, (B) 1000× and (C) 2000×. White arrows represent the magnified areas shown in column B and C. All decellularization methods resulted in complete removal of cells and preservation of the honeycomb appearance of the basal membranes and ECM scaffold. Severe wrinkle formation is visible on the remaining basal membrane viewed from the luminal side at the walls of the tubules as demonstrated in UBS 30 and less severely in UBS 60 (C, red arrows) with glomeruli (blue arrows) also partially damaged in both conditions. Scale bars: (A) 20 µm, (B) 10 μm, (C) 5 µm.
Evaluation of non-cellular spaces (NCS) in H&E stained precision-cut kidney slices (PCKS) after physical treatment with high hydrostatic pressure (HHP) and freezing-thawing cycles (FTC). (A) Native PCKS with arrows pointing at normal NCS of the Bowman capsule (yellow arrows) and the lumen of the tubules (black arrows) respectively, (B) PCKS treated with FTC, with arrows (colors as in A) pointing at the compressed NCS of bowman capsule and lumen of the tubules, (C) PCKS treated with HHP (600 MPa) showing the strongly reduced NCS in the bowman capsule (yellow arrows) and partially reduced in the lumen of the tubules (black arrows), (D) quantification with ImageJ shows a significant reduction in the area of NCS after physical treatment with FTC. Groups were compared with Kruskal–Wallis test followed by a pairwise analysis with Dunn’s test. Values are expressed as mean ± SD (native and HHP: n = 5, FTC: n = 3). Significant differences are indicated by (*p ⩽ 0.05) and (**p ⩽ 0.01).
Categories of the scoring system and their respective parameters for the examination of decellularized PCKS. The scoring system is divided into 3 categories. Scores were assigned from 1-4 signifying the best to worst achieved result. The max value refers to the highest achieved result for quantitative assays within the composition category
The extracellular matrix (ECM) obtained by decellularization provides scaffolds with the natural complex architecture and biochemical composition of the target organ. Whole kidney decellularization by perfusion uses the vasculature to remove cells leaving a scaffold that can be recellularized with patient-specific cells. However, decellularization and recellularization are highly complex processes that require intensive optimization of various parameters. In pursuit of this, a huge number of animals must be sacrificed. Therefore, we used precision-cut kidney slices (PCKS) as a source for natural scaffolds, which were decellularized by immersion in chemical reagents allowing the examination of more parameters with less animals. However, chemical reagents have a damaging effect on the structure and components of the ECM. Therefore, this study aimed at investigating the effects of physical treatment methods on the effectiveness of PCKS decellularization by immersion in chemical reagents (CHEM). PCKS were treated physically before or during immersion in chemicals (CHEM) with high hydrostatic pressure (HHP), freezing-thawing cycles (FTC) or in an ultrasonic bath system (UBS). Biochemical and DNA quantification as well as structural evaluation with conventional histology and scanning electron microscopy (SEM) were performed. Compared to decellularization by CHEM alone, FTC treatment prior to CHEM was the most effective in reducing DNA while also preserving glycosaminoglycan content (GAG). Moreover, while UBS resulted in a comparable reduction of DNA, it was the least effective in retaining GAGs. In contrast, despite the pretreatment with HHP with pressures up to 200 MPa, it was the least effective in DNA removal. Histological scoring showed that HHP scaffolds received the best score followed by UBS, FTC and CHEM scaffolds. However further analysis with SEM demonstrated a higher deterioration of the ultrastructure in UBS scaffolds. Altogether, pretreatment with FTC prior to CHEM resulted in a better balance between DNA removal and structural preservation.
Mimicking the multilayered structure of blood vessels and constructing a porous inner surface are two effective approaches to achieve mechanical matching and rapid endothelialization to reduce occlusion in small-diameter vascular grafts. However, the fabrication processes are complex and time consuming, thus complicating the fabrication of personalized vascular grafts. A simple and versatile strategy is proposed to prepare the skeleton of vascular grafts by rolling self-adhesive polymer films. These polymer films are directly fabricated by dropping a polymer solution on a water surface. For the tubes, the length and wall thickness are controlled by the rolling number and position of each film, whereas the structure and properties are tailored by regulating the solution composition. Double-layer vascular grafts (DLVGs) with microporous inner layers and impermeable outer layers are constructed; a microporous layer is formed by introducing a hydrophilic polymer into a polyurethane (PU) solution. DLVGs exhibit a J-shaped stress-strain deformation profile and compliance comparable to that of coronary arteries, sufficient suture retention strength and burst pressure, suitable hemocompatibility, significant adhesion, and proliferation of human umbilical vein endothelial cells. Freshly prepared PU tubes exhibit good cytocompatibility. Thus, this strategy demonstrates potential for rapid construction of small-diameter vascular grafts for individual customization.
The poor mechanical strength and bioactivity of magnesium phosphate bone cements (MPCs) are the vital defects for bone reconstruction. Clay minerals have been widely used in biomedical field due to the good reinforcing property and cytocompatibility. Here, laponite, sepiolite or halloysite were incorporated to fabricate MPCs composite, and the composition, microstructure, setting time, compressive strength, thermal stability, degradation performance, in vitro bioactivity and cell viability of MPCs composite were investigated. The results suggested that the MPCs composite possessed appropriate setting time, high mechanical strength and good thermal stability. By contrast, MPCs composite containing 3.0 wt.% of sepiolite presented the highest compressive strength (33.45 ± 2.87MPa) and the best thermal stability. The degradation ratio of MPCs composite was slightly slower than that of MPCs, and varied in simulated body fluid and phosphate buffer solution. Therefore, the obtained MPCs composite with excellent bioactivity and cell viability was expected to meet the clinical requirements for filling bone defect.
The response sensitivity of surface material plays an important role in adjustable nano-bio interaction in vivo. In this present, a zwitterionic polymer (polyzwitterion) containing quaternary ammonium cation and sulfonamide anion (PMPTSA) was synthesized by RAFT polymerization to explore the pH responsive behavior in tumors. The PMPTSA-coated gold nanoparticles (PMPTSA-@-Au NPs) showed zwitterionic nature such as antifouling ability, low cellular uptake and prolonged circulation time similar with common hydrophilic polymers, including polyethylene glycol (PEG), poly(carboxybetaine methacrylate) (PCBMA) and poly (sulfobetaine methacrylate) (PSBMA) functional gold nanoparticles in physiological environment (pH7.4). A high sensitivity and reversible positive charge conversion of P(MPTSA)-@-Au NPs at tumor slight acidic microenvironment(~pH6.8) leaded to an enhanced cellular internalization than that at pH7.4 and increased tumor accumulation compared with PEG, PCB and PSB functional gold nanoparticles. The highly pH responsive PMPTSA will provide the promising application in cancer nano-medicine.
Purpose: The lack of mechanical support in the bone tunnel formed after core decompression (CD) often results in a poor therapeutic effect in osteonecrosis of the femoral head (ONFH). The nano-hydroxyapatite/polyamide 66 (n-HA/P66) has excellent biocompatibility and mechanical properties and has been widely used in bone regeneration. The present study aimed to evaluate the effects of n-HA/P66 scaffold treatment in a dog model of ONFH. Method: A Finite Element Analysis (FEA) was performed to analyze the mechanical changes in the femoral head after CD and n-HA/P66 scaffold or tantalum rod implantation. Fifteen male beagles were selected to establish the model of ONFH by liquid nitrogen freezing method, and the models were identified by X-ray and MRI 4 weeks after modeling and randomly divided into three groups. Nine weeks later, femoral head samples were taken for morphology, micro-CT, and histological examination. Results: The FEA showed that the n-HA/P66 scaffold proved the structural support in the bone tunnel, similar to the tantalum rod. The morphology showed that the femoral head with n-HA/P66 implantation is intact, while the femoral heads in the model group and CD group are collapsing. Moreover, the micro-CT results of the n-HA/P66 scaffold group were better than the model group and the CD group, and the interface between the n-HA/P66 scaffold and bone tissue is blurred. Furthermore, the histological result also verifies the alterations in micro-CT, and bone tissue grows in the bone tunnel with n-HA/P66 scaffold implanted while few in the CD group. Conclusion: The n-HA/P66 scaffold implantation can provide mechanical support to the subchondral bone and relieve high stress induced by core decompression. The n-HA/P66 scaffold can treat femoral head necrosis and provide the bone tissue growth scaffold for the femoral head after CD to promote bone tissue regeneration.
Cell-based assays are essential in vitro tools for understanding basic cell biology, pathophysiology of diseases and mechanism of drug actions Most cancer studies have utilized two-dimensional (2D) cell culture methods, which have their shortcomings including lack of cell-ECM interactions and three-dimensional 3D geometry, and inaccurate representation of cell polarity. Hence, 3D matrices are being increasingly used to study the effect of 3D niche on cell behaviour. Till date, are very few systematic studies have been done to show comparison of cell behaviour when seeded on the surface and encapsulated inside the matrix. In this study, we fabricated poly(ethylene glycol) (PEG) and gelatin-based matrices using UV mediated photo-polymerization to establish 2D and 3D cell culture methods using breast cancer MDA-MB-231 cells. We have found that the adhesion and spreading of cells on the gel surface is different from that when embedded in gels. The stiffness of PEGDA-GelMA hydrogels with lower concentration of GelMA is lower than that with higher GelMA; further, those with higher overall concentration of polymers (>5%) retain their mechanical integrity and do not degrade even after 7 days. Physical characterization of these matrices demonstrate their optimal pore size, mechanical stiffness and degradation, which are further tunable for tissue engineering, regenerative medicine, drug delivery and cancer studies. Additionally, these semi-synthetic PEGDA-GelMA matrices are transparent in nature, thereby, allowing easy imaging of cells in 3D. The system developed here can be used for short and long term cell culture and can be potentially explored for cell migration and metastasis studies.
The goal of this study is to fabricate biocompatible and minimally invasive bone tissue engineering scaffolds that allow in situ photocuring and further investigate the effect on the mechanical properties of the scaffold due to the prevailing conditions around defect sites, such as the shift in pH from the physiological environment, swelling due to accumulation of fluids during inflammation, etc. A novel approach of incorporating a general full factorial Design of Experiment (DOE) model to study the effect of the local environment of the tissue defect on the mechanical properties of these injectable and photocurable scaffolds has been formulated. Moreover, the cross-interaction between factors, such as pH and immersion time, was studied as an effect on the response variable. This study encompasses the fabrication, and uniaxial mechanical testing of polyethylene glycol dimethacrylate (PEGDMA) scaffolds for injectable tissue engineering applications, along with the loss in weight of the scaffolds over 72 h in a varying pH environment that mimics in vivo conditions around a defect. The DOE model was constructed with three factors: the combination of PEGDMA and nanohydroxyapatite, referred to as biopolymer blend, the pH of the buffer solution used for immersing the scaffolds, and the immersion time of the scaffolds in the buffer solution. The response variables recorded were compressive modulus, compressive strength, and the weight loss of the scaffolds over 72 h of immersion in phosphate-buffered saline at respective pH. The statistical model analysis provided adequate information in explaining a strong interaction of the factors on the response variables. Further, it revealed a significant cross-interaction between the factors. The factors such as the biopolymer blend and pH of the buffer solution significantly affected the response variables, compressive modulus, and strength. At the same time, the immersion time had a strong effect on the loss in weight from the scaffolds over 72 h of soaking in the buffer solution. The biocompatibility study done using a set of fluorescent dyes for these tissue scaffolds highlighted an enhancement in the preosteoblasts (OB-6) cell attachment over time up to day 14. The representative fluorescent images revealed an increase in cell attachment activity. This study has opened a new horizon in optimizing the factors represented in the DOE model for tunable PEGDMA-based injectable scaffold systems with enhanced bioactivity.
Diabetes is an emerging global epidemic that affects more that 285 million people worldwide. Engineering of endocrine pancreas tissue holds great promise for the future of diabetes therapy. Here we demonstrate the feasibility of re-engineering decellularized organ scaffolds using regenerative cell source. We differentiated human pluripotent stem cells (hPSC) towards pancreatic progenitor (PP) lineage and repopulated decellularized organ scaffolds with these hPSC-PP cells. We observed that hPSCs cultured and differentiated as aggregates are more suitable for organ repopulation than isolated single cell suspension. However, recellularization with hPSC-PP aggregates require a more extensive vascular support, which was found to be superior in decellularized liver over the decellularized pancreas scaffolds. Upon continued culture for 9 days with chemical induction in the bioreactor, the seeded hPSC-PP aggregates demonstrated extensive and uniform cellular repopulation and viability throughout the thickness of the liver scaffolds. Furthermore, the decellularized liver scaffolds was supportive of the endocrine cell fate of the engrafted cells. Our novel strategy to engineer endocrine pancreas construct is expected to find potential applications in preclinical testing, drug discovery and diabetes therapy.
Nanotopography can promote osseointegration, but how BMMSCs respond to this physical stimulus is unclear. Here, we found that early exposure of BMMSCs to nanotopography (6-hour) caused mitochondrial fission rather than fusion, which was necessary for osseointegration. We analyzed the changes in mitochondrial morphology and function of BMMSCs located on the surfaces of NT100(100-nanometer nanotubes) and ST (Smooth) by super-resolution microscopy and other techniques. Then, we found that both ST and NT100 caused a significant increase in mitochondrial fission early on, but NT100 caused mitochondrial fission much earlier than those on ST. In addition, the mitochondrial functional statuses were good at the 6-hour time point, this is at odds with the conventional wisdom that fusion is good. This fission phenomenon adequately protected mitochondrial membrane potential and respiration and reduced ROS. Interestingly, the mitochondrial membrane potential and oxygen consumption rate of BMMSCs were reduced when mitochondrial fission was inhibited by Mdivi-1 in the early stage. In addition, the effect on osseointegration was significantly worse, and this effect did not improve with time. Taken together, the findings indicate that early mitochondrial fission plays an important role in nanotopography-mediated promotion of osseointegration, which is of great significance to the surface structure design of biomaterials.
We developed a pH/GSH dual-responsive smart nano-drug delivery system to achieve targeted release of a chemotherapeutic drug at breast tumor site. Doxorubicin (DOX) was linked to polyethylene glycol through cis-aconitic anhydride and disulfide bonds to obtain the PEG-SS-CA-DOX prodrug, which spontaneously assembled into nanomicelles with a particle size of 48±0.45 nm. PEG-SS-CA-DOX micelles achieved an efficient and rapid release of DOX under dual stimulation by weak acidic pH and high GSH content of tumors, with the release amount reaching 88.0% within 48 hours. Cellular uptake experiments demonstrated that PEG-SS-CA-DOX micelles could efficiently transport DOX into cells and rapidly release it in the tumor microenvironment. In addition, in vivo antitumor experiments showed that PEG-SS-CA-DOX had a high inhibition rate of 70% against 4T1 breast cancer cells along with good biosafety. In conclusion, dual-responsive smart nanomicelles can achieve tumor-targeted drug delivery and specific drug release, thus improving therapeutic efficacy of drugs.
Currently, one of the most severe clinical concerns is post-surgical tissue adhesions. Using films or hydrogel to separate the injured tissue from surrounding tissues has proven the most effective method for minimizing adhesions. Therefore, by combining dual crosslinking with calcium ions (Ca2+) and tetrakis(hydroxymethyl) phosphonium chloride (THPC), we were able to create a novel, stable, robust, and injectable dual crosslinking hydrogel using albumin (BSA). This dual crosslinking has preserved the microstructure of the hydrogel network during the degradation process, which contributes to the hydrogel's mechanical strength and stability in a physiological situation. At 60% strain, compressive stress was 48.81 kPa obtained. It also demonstrated excellent self-healing characteristics (within 25 mins), tissue adhesion, excellent cytocompatibility, and a quick gelling time of 27 ± 6 sec. Based on these features, the dual crosslinked injectable hydrogels might find exciting applications in biomedicine, particularly for preventing post-surgical adhesions.
Since wound dressing has been considered a promising strategy to improve wound healing, recent attention has been focused on the development of modern wound dressings based on synthetic and bioactive polymers. In this study, we prepared a multifunctional wound dressing based on carboxymethyl chitosan/sodium alginate hydrogel containing a nanostructured lipid carrier in which simvastatin has been encapsulated. This dressing aimed to act as a barrier against pathogens, eliminate excess exudates, and accelerate wound healing by increasing the production of vascular endothelial growth factor (VEGF). Among various fabricated composites of dressing, the hydrogel composite with a carboxymethyl chitosan/sodium alginate ratio of 1:2 had an average pore size of about 98.44 ± 26.9 μm and showed 707 ± 31.9 % swelling and a 2116 ± 79.2 g/m2.per day water vapor transfer rate (WVTR), demonstrating appropriate properties for absorbing exudates and maintaining wound moisture. The nanostructured lipid carrier with optimum composition and properties had a spherical shape and uniform particle size distribution (74.46 ±7.9 nm). The prepared nanocomposite hydrogel displayed excellent antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria as well as high biocompatibility on L929 mouse fibroblast cells. It can release the loaded simvastatin drug slowly and over a prolonged period of time. The highest drug release occurred (80%) within 14 days. The results showed that this novel nanocomposite could be a promising candidate as a wound dressing for treating various chronic wounds in skin tissues.
The identification of degraded products of implanted scaffolds is desirable to avoid regulatory concerns. In vivo identification of products produced by the degradation of natural protein-based scaffolds is complex and demands the establishment of a routine analytical method. In this study, we developed a method for the identification of peptides produced by the degradation of zein both in vitro and in vivo using HPLC-MS/MS. For in vitro experiments, zein was degraded enzymatically and analyzed produced peptides. In vitro study showed cytocompatibility of peptides present in the hydrolysate of zein with no induction of apoptosis and cell senescence. For in vivo experiment, zein gels were prepared and subcutaneously implanted in rats. Peptides produced by the degradation of zein were identified and some are selected as targeted (unique peptides) and two were synthesized as the main sequence of these peptides. Further, peptide analysis using HPLC-MS/MS of different organs after 2 and 8 weeks of implantation of zein gel in rats. It was found that zein-originated peptides were accumulated in different organs. QQHIIGGALF or long peptides with same fractions were identified as unique peptides. These peptides were also found in control rats with regular rat feed (having corn) which the degradation of implanted zein biomaterial food related peptides of non-toxic nature. Furthermore, H&E staining exhibited normal features. Overall, zein hydrolysate has cytocompatibility and did not found to induce organ toxicity and QQHIIGGALF can act as a standard peptide for determining zein degradation. The study also provides the feasibility of complex analysis of the identification of degradation products of protein-based scaffolds.
Schematic illustration of the spectra of macrophage phenotypes. Abbreviations: IFN-γ, interferon-gamma; LPS, lipopolysaccharide; CD, cluster of differentiation; TLRs, Toll-like receptors; IL, interleukin; TNF-α, tumor necrosis factor alpha, VEGF, vascular endothelial growth factor; IRF, interferon regulatory factor; MMP, matrix metalloproteinase; TGF-β, transforming growth factor beta; TIMP, tissue inhibitor of metalloproteinases; ICs, immune complexes; PGE2, prostaglandin E2, PAF, platelet-activating factor.
Typical pro-regenerative immune microenvironment mediated by ECM scaffold materials. After ECM implantation, the amounts of neutrophils and macrophages increase significantly due to the chemotactic activity of ECM debris. Macrophages are differentiated from the migrating monocytes in the bloodstream or recruited from the tissue-resident macrophages. Neutrophils and macrophages promote further ECM degradation by producing related enzymes. ECM debris that is engulfed by or in contact with the macrophages changes the gene expression and activates the macrophages toward the pro-regenerative M2-like phenotype. During this process, neutrophils release cytokines including IL-1β, IL-6, and IL-10 to promote M2-like macrophage polarization. Moreover, apoptotic neutrophils present the phosphatidylserine signal to induce the phagocytosis of macrophages. The neutrophil fragments engulfed shift macrophages from the M1-like to the M2-like phenotype. The pro-regenerative macrophages present a long shape. They influence the differentiation of CD4⁺ T cells by cytokines along with the antigen presenting process. In turn, T cells promote the polarization of macrophages by secreting signaling molecules. The pro-regenerative signaling is magnified by the interaction between the innate and adaptive immune systems. Dendritic cells are important antigen-presenting cells. However, the interaction between T cells and dendritic cells were challenged in the immune microenvironment mediated by ECM scaffolds.
Interaction between macrophages and ECM scaffold materials. Matrix-bound nanovesicles transfer microRNA and protein signaling molecules into the macrophages and affect M2-related gene expression. ECM proteins modulate macrophage polarization depending on their combination with integrins and a metabolic signaling axis formed by the amino acid sufficiency signal in lysosomes, IL-4, and a complex of relevant sensors and responders. The complex consists of Lamtor 1, v-ATPase, and mTORC1. PGs and GAG chains bind to cellular surface receptors such as CD44, TLR2, and TLR4 and initiate downstream signaling pathways.
Biomaterials are one of efficient treatment options for tissue defects in regenerative medicine. Compared to synthetic materials which tend to induce chronic inflammatory response and fibrous capsule, extracellular matrix (ECM) scaffold materials composed of biopolymers are thought to be capable of inducing a pro-regenerative immune microenvironment and facilitate wound healing. Immune cells are the first line of response to implanted biomaterials. In particular, macrophages greatly affect cell behavior and the ultimate treatment outcome based on multiple cell phenotypes with various functions. The macrophage polarization status is considered as a general reflection of the characteristics of the immune microenvironment. Since numerous reports has emphasized the limitation of classical M1/M2 nomenclature, high-resolution techniques such as single-cell sequencing has been applied to recognize distinct macrophage phenotypes involved in host responses to biomaterials. After reviewing latest literatures that explored the immune microenvironment mediated by ECM scaffolds, this paper describe the behaviors of highly heterogeneous and plastic macrophages subpopulations which affect the tissue regeneration. The mechanisms by which ECM scaffolds interact with macrophages are also discussed from the perspectives of the ECM ultrastructure along with the nucleic acid, protein, and proteoglycan compositions, in order to provide targets for potential therapeutic modulation in regenerative medicine.
Hybrid scaffolds from natural and synthetic polymers have been widely used due to the complementary nature of their physical and biological properties. The aim of the present study, therefore, has been to analyze in vivo a bilayer scaffold of poly(lactide-co-glycolide) (PLGA)/fibrin electrospun membrane and fibrin hydrogel layer on a rat skin model. Fibroblasts were cultivated in the fibrin hydrogel layer and keratinocytes on the electrospun membrane to generate a skin substitute. The scaffolds without and with cells were tested in a full-thickness wound model in Wistar Kyoto rats. The histological results demonstrated that the scaffolds induced granulation tissue growth, collagen deposition and epithelial tissue remodeling. The wound-healing markers showed no difference in scaffolds when compared with the positive control. Activities of antioxidant enzymes were decreased concerning the positive and negative control. The findings suggest that the scaffolds contributed to the granulation tissue formation and the early collagen deposition, maintaining an anti-inflammatory microenvironment.
Synthetic hydrogels composed of polymer pore frames are commonly used in medicine, from pharmacologically targeted drug delivery to the creation of bioengineering constructions used in implantation surgery. Among various possible materials, the most common are poly-[N(2-hydroxypropyl)methacrylamide] (pHPMA) derivatives. One of the pHPMA derivatives is biocompatible hydrogel, NeuroGel. Upon contact with nervous tissue, the NeuroGel's structure can support the chemical and physiological conditions of the tissue necessary for the growth of native cells. Owing to the different pore diameters in the hydrogel, not only macromolecules, but also cells can migrate. This study evaluated the differentiation of bone marrow stromal cells (BMSCs) into neurons, as well as the effectiveness of using this biofabricated system in spinal cord injury in vivo. The hydrogel was populated with BMSCs by injection or rehydration. After cultivation, these fragments (hydrogel + BMSCs) were implanted into the injured rat spinal cord. Fragments were immunostained before implantation and seven months after implantation. During cultivation with the hydrogel, both variants (injection/rehydration) of the BMSCs culture retained their viability and demonstrated a significant number of Ki-67-positive cells, indicating the preservation of their proliferative activity. In hydrogel fragments, BMSCs also maintained their viability during the period of cocultivation and were Ki-67-positive, but in significantly fewer numbers than in the cell culture. In addition, in fragments of hydrogel with grafted BMSCs, both by the injection or rehydration versions, we observed a significant number up to 57%–63.5% of NeuN-positive cells. These results suggest that the heterogeneous pHPMA hydrogel promotes neuronal differentiation of bone marrow-derived stromal cells. Furthermore, these data demonstrate the possible use of NeuroGel implants with grafted BMSCs for implantation into damaged areas of the spinal cord, with subsequent nerve fiber germination, nerve cell regeneration, and damaged segment restoration.
Synthetic hydrogels composed of polymer pore frames are commonly used in medicine, from pharmacologically targeted drug delivery to the creation of bioengineering constructions used in implantation surgery. Among various possible materials, the most common are poly-[N(2-hydroxypropyl)methacrylamide] (pHPMA) derivatives. One of the pHPMA derivatives is biocompatible hydrogel, NeuroGel. Upon contact with nervous tissue, the NeuroGel's structure can support the chemical and physiological conditions of the tissue necessary for the growth of native cells. Owing to the different pore diameters in the hydrogel, not only macromolecules, but also cells can migrate. This study evaluated the differentiation of bone marrow stromal cells (BMSCs) into neurons, as well as the effectiveness ofusing this biofabricated system in spinal cord injury in vivo. The hydrogel was populated with BMSCs by injection or rehydration. After cultivation, these fragments (hydrogel+BMSCs) were implanted into the injured rat spinal cord. Fragments were immunostained before implantation and seven months after implantation. During cultivation with the hydrogel, both variants (injection/rehydration) of the BMSCs culture retained their viability and demonstrated a significant number of Ki-67-positive cells, indicating the preservation of their proliferative activity. In hydrogel fragments, BMSCs also maintained their viability during the period of cocultivation and were Ki-67-positive, but in significantly fewer numbers than in the cell culture. In addition, in fragments of hydrogel with grafted BMSCs, both by the injection or rehydration versions, we observed a significant number up to 57-63,5% of NeuN-positive cells. These results suggest that the heterogeneous pHPMA hydrogel promotes neuronal differentiation of bone marrow-derived stromal cells. Furthermore, these data demonstrate the possible use of NeuroGel implants with grafted BMSCs for implantation into damaged areas of the spinal cord, with subsequent nerve fiber germination, nerve cell regeneration, and damaged segment restoration.
As the main inorganic components of human bones and teeth, hydroxyapatite (HA) with excellent bioactivity and biocompatibility shows great potential in the bone tissue engineering field. Marine mussel-inspired polydopamine (PDA) possess unique functional groups and thus can absorb the calcium ions from extracellular fluid (ECF), thereby triggering precipitation of HA. This study is based on a two-step strategy. Using the chemical activity of PDA, polyvinyl alcohol/polylactic acid (PVA/PLA) braids were coated with a PDA layer. that serves as a template for electrochemical deposition of a HA layer. The test results indicate that the resulting HA crystals were assembled on the polymer fibers in an urchin-like manner. with a stratified structure. Subsequently, the PDA/HA-PVA/PLA braided bone scaffolds were immersed in simulated body fluid (SBF) for ten days, after which the bone scaffolds were found to be completely coated by HA, indicating a good biomineralization capability. Compared with PVA/PLA braids,the cell activity of PDA/HA scaffolded by dopamine-assisted electrodeposition was 178.8%.This HA coating layer inspired by biochemical strategy may be useful in the filed of bone tissue engineering.
The schematic overview. (a) The alveolar barriers are fabricated by sequential inkjet bioprinting of lung microvascular endothelial cells, collagen type I, lung fibroblasts, and alveolar epithelial cells (types I and II). For tissue maturation, the printed alveolar barrier was cultured for seven days with the epithelium exposed to air. (b) Fibrosis was induced by treatment with TGF-β1 in the alveolar barrier model fabricated by inkjet bioprinting. (c) The fibrotic tissue was treated with the anti-fibrotic drugs nintedanib and pirfenidone. (d) Fibrotic phenotype and drug efficacy were evaluated for the PF model and therapeutic model, respectively.
Histological analysis of PF induced and therapeutic treated tissues. (a) The degree of apoptosis in model was confirmed by TUNEL staining. TUNEL-positive apoptotic cells are stained green. The nuclei are counterstained with PI (red). Scale bar = 100 μm. (b) Cross-sectional images of the alveolar barrier model were stained with H&E. Cytoplasm and collagen were stained pink and cell nuclei were stained purple. Scale bar = 100 μm. (c) Alveolar barrier models were stained with Picro Sirius Red to visualize fibrotic region. The cytoplasm was stained yellow and collagen fibers were stained red. Scale bar = 50 μm. Quantification of representative images is shown on the right. (d) Cross-sectional images of tissues stained with Alcian blue and nuclear fast red. Nuclei and surfactants were stained purple and light blue, respectively. The arrowhead indicates the accumulation of surfactant at the surface area. Scale bar = 100 μm. Quantification of representative images is shown on the right.
Confirmation of biomarker alteration through immunohistochemical analysis. (a)–(c) Cross-sectional immunofluorescent images and (d) confocal immunofluorescent images from the top of the tissues. Each used antibody is indicated in green, (a) vimentin; (b) NF-κB p65; (c) fibronectin; and (d) αSMA. In all results, nuclei were stained with Hoechst33342 (blue). Scale bars = 100 μm. Quantification of representative images is shown at the bottom.
Comparison of gene expression profiles between control, PF, and drug-treated models. Relative mRNA expression was measured via qPCR using primer pairs that can specifically detect (a) vimentin, (b) MMP-9, (c) COL1A1, (d) FN1, (e) ACTA2, and (f) SFTPA1. Each expression level was normalized to that of control group. (n = 5). Information on mRNA expression levels (mean ± S.E.M.) is in table S1, supplementary data.
Pulmonary fibrosis is known as a chronic and irreversible disease characterized by excessive extracellular matrix accumulation and lung architecture changes. Large efforts have been made to develop prospective treatments and study the etiology of pulmonary fibrotic diseases utilizing animal models and spherical organoids. As part of these efforts, we created an all-inkjet-printed three-dimensional (3D) alveolar barrier model that can be used for anti-fibrotic drug discovery. Then, we developed a pulmonary fibrosis model by treating the 3D alveolar barrier with pro-fibrotic cytokine and confirmed that it is suitable for the fibrosis model by observing changes in structural deposition, pulmonary function, epithelial-mesenchymal transition, and fibrosis markers. The model was tested with two approved anti-fibrotic drugs, and we could observe that the symptoms in the disease model were alleviated. Consequently, structural abnormalities and changes in mRNA expression were found in the developed fibrosis model, which were shown to be recovered in all drug treatment groups. The all-inkjet-printed alveolar barrier model was reproducible for disease onset and therapeutic effects in the human body. This finding emphasized that the in vitro artificial tissue with faithfully implemented 3D microstructures using bioprinting technology may be employed as a novel testing platform and disease model to evaluate potential drug efficacy.
Clinical management of cyclophosphamide (CYP) results in numerous side effects including hemorrhagic cystitis (HC), which is characterized by inflammation and oxidative stress damage. Intravesical hyaluronic acid (HA) supplementation, a therapeutic method to restore barrier function of bladder, avoid the stimulation of metabolic toxicants on bladder and reduce inflammatory response, has shown good results in acute or chronic bladder diseases. However, there are unmet medical needs for the treatment of HC to temporarily restore bladder barrier and reduce inflammation. Herein, sulfhydryl functionalized HA (HA-SH) and dimethyl sulfoxide (DMSO) were used to prepared a hydrogel system for optimizing the treatment of HC. We systematically evaluated the physicochemical of hydrogels and their roles in a rat model of CYP-induced HC. The prepared hydrogels exhibited outstanding gel forming properties, injectability, and biosafety. Swelling and retention studies showed that hydrogels were stable and could prolong the residence time of HA in the bladder. Histopathology and vascular permeability studies indicated that the hydrogels significantly attenuated bladder injury caused by CYP administration. Moreover, the hydrogels also showed excellent anti-inflammation and anti-oxidation properties. In conclusion, these data suggest that intravesical instillation of HA-SH/DMSO hydrogels reduces CYP-induced bladder toxicity and this work provides a new strategy for the prevention and early treatment of HC.
Regenerative bone implants should be completely replaced by new bone within a period of time corresponding to the growth rate of native bone. To meet this requirement, suitable biomaterials must be biodegradable and promote osteogenesis. The combination of slowly degrading but osteoconductive calcium phosphates (CPs) with rapidly degrading and mechanically more resilient magnesium phosphates represents a promising material class for this purpose. In order to create the best possible conditions for optimal implant integration, microporous calcium magnesium phosphate (CMP) cements were processed using 3D powder printing. This technique enables the production of a defect-adapted implant with an optimal fit and a high degree of open porosity to promote bone ingrowth. Four different compositions of 3D printed CMP ceramics were investigated with regard to essential properties of bone implants, including chemical composition, porosity, microstructure, mechanical strength, and cytocompatibility. The ceramics consisted of farringtonite (Mg 3 (PO 4 ) 2 ) and stanfieldite (Ca 4 Mg 5 (PO 4 ) 6 ), with either struvite (NH 4 MgPO 4 ·6H 2 O) or newberyite (MgHPO 4 ·3H 2 O) and brushite (CaHPO 4 ·2H 2 O) as additional phases. The CMP materials showed open porosities between 13 and 28% and compressive strengths between 11 and 17 MPa, which was significantly higher, as compared with clinically established CP. The cytocompatibility was evaluated with the human fetal osteoblast cell line hFOB 1.19 and was proven to be equal or to even exceed that of tricalcium phosphate. Furthermore, a release of 4–8 mg magnesium and phosphate ions per mg scaffold material could be determined for CMPs over a period of 21 d. In the case of struvite containing CMPs the chemical dissolution of the cement matrix was combined with a physical degradation, which resulted in a mass loss of up to 3.1 wt%. In addition to its beneficial physical and biological properties, the proven continuous chemical degradation and bioactivity in the form of CP precipitation indicate an enhanced bone regeneration potential of CMPs.
Background and Purpose Metabolic reprogramming “Warburg effect” and immune checkpoint signaling are immunosuppressive hallmarks of Triple-Negative Breast Cancer (TNBC) contributing to the limited clinical applicability of immunotherapy. Biomaterials arise as novel tools for immunomodulation of the tumor microenvironment (TME) that can be used alongside conventional immunotherapeutics. Chitosan and lecithin are examples of versatile biomaterials with interesting immunomodulatory properties. In this study, we aimed at investigation of the role of carefully designed hybrid nanoparticles (NPs) on common mediators of both PD-L1 expression and glycolytic metabolism. Materials and Methods Hybrid lecithin-chitosan NPs were prepared and characterized. Their intracellular concentration, localization and effect on the viability of MDA-MB-231 cells were assessed. Glycolytic metabolism was quantified by measuring glucose consumption, ATP generation, lactate production and extracellular acidification. Nitric oxide (NO) production was quantified using Greiss reagent. Gene expression of iNOS, PI3K, Akt, mTOR, HIF-1α and PD-L1 was quantified by reverse transcription and q-RT-PCR. Results Chitosan, lecithin and the NPs-formulated forms have been shown to influence the “Warburg effect” and immune checkpoint signaling of TNBC cells differently. The composition of the hybrid systems dictated their subcellular localization and hence the positive or negative impact on the immunosuppressive characteristics of TNBC cells. Conclusions Carefully engineered hybrid lecithin-chitosan NPs could convert the immune-suppressive microenvironment of TNBC to an immune-active microenvironment via reduction of PD-L1 expression and reversal of the Warburg effect.
Mesenchymal stem cells (MSCs) are an ideal seed cell for tissue engineering and stem cell transplantation. MSCs combined with biological scaffolds play an important role in promoting the repair of cutaneous wound. However, direct administration of MSCs is challenging for MSCs survival and integration into tissues. Providing MSCs with a biocompatible scaffold can improve MSCs survival, but the effect of Gelatin Methacrylate (GelMA) loaded MSCs from umbilical cord mesenchymal stem cells (UC-MSCs) in wound healing remains unknown. Here, we investigated the ability of GelMA with UC-MSCs complexes to promote migration and proliferation and the effect on wound healing in mouse models. We discovered that UC-MSCs attached to GelMA and promoted the proliferation and migration of fibroblasts. Both UC-MSCs and UC-MSCs-derived extracellular vesicles accelerated wound healing. MSC+GMs application decreased expression of transforming growth factor-β (TGF-β) and Type III collagen (Col3) in vivo, leading to new collagen deposition and angiogenesis, and accelerate wound healing and skin tissue regeneration. Taken together, these findings indicate MSC + GMs can promote wound healing by regulating wound healing-related factors in the paracrine. Therefore, our research proves that GelMA is an ideal scaffold for the top management of UC-MSCs in wound healing medical practice.
Magnesium (Mg) and its alloys have attracted attention as biodegradable material for biomedical applications owing to their favourable biomedical properties. The mechanical properties of Mg alloys are comparable to those of bone, and they are biocompatible. Mg is a factor in many enzymes that are essential for human metabolism and is vital trace element for human enzymes. Before biomedical applications, the early stage or fast degradation of Mg and its alloys in the physiological environment should be controlled. The degradation of Mg alloys is a critical criterion that can be controlled by a surface modification which is an effective process for conserving their desired properties. Different coating methods have been employed to modify Mg surfaces to provide good corrosion resistance and biocompatibility. This review aims to provide information on different coatings and discuss their physical and biological properties. Finally, challenges are proposed, and future perspectives are discussed.
Electrode impendence is one of the greatest challenges facing neural interfacing medical devices and the use of electrical stimulation-based therapies in the fields of neurology and regenerative medicine. Maximizing contact between electronics and tissue would allow for more accurate recordings of neural activity and to stimulate with less power in implantable devices as electric signals could be more precisely transferred by a stable interfacial area. Neural environments, inherently wet and ion-rich, present a unique challenge for traditional conductive adhesives. As such, we look to marine mussels that use a DOPA-containing proteinaceous excretion to adhere to a variety of substrates for inspiration. By functionalizing alginate, which is an abundantly available natural polymer, with the catechol residues DOPA contains, we developed a hydrogel-based matrix to which carbon-based nanofiller was added to render it conductive. The synthesized product had adhesive energy within the range of previously reported mussel-based polymers, good electrical properties and was not cytotoxic to brain derived neural precursor cells (NPCs).
The repair of irregular and complex critical bone defects remains a challenge in clinical practice. The application of 3D-printed bioceramics particle/polymer composite scaffolds in bone tissue engineering has been widely studied. At present, the inorganic particle content of the composite scaffolds is generally low, resulting in poor osteogenic activity. However, scaffold with high inorganic content are highly brittle, difficult to operate during surgery, and cannot be in close contact with surrounding bones. Therefore, it is of great significance to design a " surgery-friendly " scaffold with high bioceramic content and good ductility. In this study, we used the solvent method to add high concentration (wt% 70%) bioglass (BG) into polycaprolactone (PCL), and polyethylene glycol (PEG) was used as plasticizer to prepare 70%BG/ PCL composite scaffolds with high ductility using 3D printing technology. In vitro experiments showed that the scaffold had good mechanical properties: easy extension, easy folding and strong compressive resistance. It also showed good performance in biocompatibility and osteogenic activity. It was further observed that compared with pure BG or PCL implantation, the scaffold with higher BG content could have more new bone tissue appeared after 12 weeks. All these results indicate that 3D-printed 70%BG/ PCL scaffolds have great potential for personalized repair of bone defects.
The specific chemotaxis of macrophages to inflammatory site makes them good candidate for inflammation drug delivery. However, the loading capacity of free drug is low. The goal of the manuscript is to enhance the loading capacity by encapsulating drug onto iron oxide nanoparticles (IONPs) and investigate the size effect on the cellular uptake. IONPs with different sizes (10 nm, 70 nm, and 200 nm) were synthesized. The loading capacities of model drug protoporphyrin IX (PPIX) on different sized IONPs were studied, showing similar loading capacity. However, the cellular internalization of PPIX loaded IONPs (Fe 3 O 4 -PPIX) was quite different. 70 nm IONPs indicated maximum uptake by the macrophages. The results also demonstrate that the IONPs could significantly improve the loading capacity when compared with free drug. All the three sized nanoparticles demonstrated minimal effects on cellular viability and would not induce the polarization of macrophages. This study not only provides an efficient method to increase the drug loading capacity in macrophages, but also indicates the optimal size of nanoparticles for cellular uptake.
Neural networks have been cultured in vitro to investigate brain functions and diseases, clinical treatments for brain damage, and device development. However, it remains challenging to form complex neural network structures with desired orientations and connections in vitro . Here, we introduce a dynamic strategy by using diphenylalanine (FF) nanotubes for controlling physical patterns on a substrate to regulate neurite-growth orientation in cultivating neural networks. Parallel FF nanotube patterns guide neurons to develop neurites through the unidirectional FF nanotubes while restricting their polarization direction. Subsequently, the FF nanotubes disassemble and the restriction of neurites disappear, and secondary neurite development of the neural network occurs in other direction. Experiments were conducted that use the hippocampal neurons, and the results demonstrated that the cultured neural networks by using the proposed dynamic approach can form a significant cross-connected structure with substantially more lateral neural connections than static substrates. The proposed dynamic approach for neurite outgrowing enables the construction of oriented innervation and cross-connected neural networks in vitro and may explore the way for the bio-fabrication of highly complex structures in tissue engineering.
To assure the long-term safety and functional performance after implantation, it is of critical importance to completely sterilize a biomaterial implant. Ineffective sterilization can cause severe inflammation and infection at the implant site, leading to detrimental events of morbidity and even mortality. Macrophages are pivotal players in the inflammatory and foreign body response after implanting a biomaterial in the body. However, the relationship between the sterilization procedure and macrophage response has not been established. In this study, three commonly used sterilization methods, including autoclaving, ethylene oxide gas and ethanol treatment, were used to sterilize a gelatin methacryloyl (GelMA) hydrogel. The impacts of different sterilization methods on the structure and mechanical properties of the hydrogel were compared. Macrophage responses to the sterilized hydrogel were analyzed based on their morphology, viability and in vitro gene expression. It was found that the sterilization methods only marginally altered the hydrogel morphology, swelling behavior and elastic modulus, but significantly impacted macrophage gene expression within 48 hours and over 7 days in vitro. Therefore, when selecting sterilization methods for GelMA hydrogel, not only the sterility and hydrogel properties, such as material destruction and degradation caused by temperature and moisture, should be taken into consideration, but also the cellular responses to the sterilized material which could be substantially different.
The application of nanomaterials for their antibacterial properties is the subject of many studies due to antibiotic resistance of pathogen bacteria and the necessity of omitting them from food and water resources. Graphene oxide is one of the most popular candidates for antibacterial application. However, the optimum condition for such an effect is not yet clear for practical purposes. To shed light on how graphene oxide (GO) and bacteria interaction depends on size, a wide range of GO flake sizes from hundreds of µm2 going down to nano-scale as low as 10 nm2 was produced. In an in-vitro systematic study to inhibit S. aureus growth, the correlation between graphene oxide flake size, thickness, functional group density, and antibacterial activity was investigated. The GO suspension with the average size of 0.05 µm2, in the order of the size of the bacteria itself, had the best bacteriostatic effect on S. aureus with the MIC value of 8 μg/mL, well within the acceptable range for practical use. The bacteriostatic effect was measured to be a 76.2% reduction of the colony count over 2 hours of incubation and the mechanism of action was the wrapping and isolation of cells from the growth environment. Furthermore, in-vivo animal studies revealed that 16 μg/mL of the optimum GO has efficient antibacterial performance against the methicillin-resistant strains of the bacteria with an enhanced wound healing rate and tensiometrial parameters which is important for realized targets.
Schematic illustration of cell transplantation using supramolecular hydrogels with the thixotropic property. Supramolecular-crosslinked hydrogels composed of tendon-derived gelatin functionalized with ureidopyrimidinone unit (TGUPy) enabled to encapsulate cells and be injected into injured tissues for cell transplantation.
Rheological characteristics of TGUPy hydrogels. (a), (b) Shear viscosity and shear stress of TGUPy (10, 15, and 20 wt%) at 37 °C. (c) Cyclic strain change against TGUPy hydrogels. The strain was changed to 1% and 300% every 3 min at a fixed frequency (10 rad s⁻¹) at 37 °C.
(a), (b) Extrudability and force displacement curves for the injection with various syringe needle gauges. The extrudability of hydrogels pre-warmed at 37 °C was measured using a compression test (maximum stress: 50 N, compression speed: 100 mm min⁻¹). An inset photo showed the experimental setup. (c) Shear modulus of TGUPy in different concentrations. The measurement was performed at 37 °C with 1% strain and 10 rad s⁻¹. (d) Underwater stability of TG and TGUPy gels in PBS at 37 °C. Data are presented as mean ± s.d. (n = 3).
In vitro imaging of 3D cultured cells in TGUPy hydrogels. (a) Time-lapse imaging of C2C12 myoblasts encapsulated in TGUPy (15 wt%). (b) CLSM images of C2C12 myoblasts on a well plate (control) and TGUPy hydrogels (10 wt%, 15 wt%, 20 wt%). Actin and nuclei were stained with FITC-phalloidin (green) and DAPI (blue). (c) Aspect ratio of C2C12 myoblasts on a well plate and hydrogel. The 30 cells were counted using Image J. Data are presented as mean ± s.d. **P < 0.01, analyzed by one-way analysis of variance (ANOVA) with Tukey’s multiple comparison post hoc test. Scale bar represents 20 μm for (a) and 50 μm for (b).
In vivo imaging of TGUPy hydrogels. (a) Fluorescence images of TGUPy-Cy5.5 hydrogel at 6 h and day 1, 3, 7 after subcutaneous injection in mice. (b) Fluorescence intensity of TGUPy-Cy5.5 hydrogels after the injection. (c) Procedure of the preparation of VML models of mice. (d) Luminescence images of luciferase-expressing C2C12 cells transplanted in VML models of mice using TGUPy hydrogel. (e) luminescence counts of C2C12 cells after the transplantation. Data are presented as mean ± s.d. (n = 4 for (b) and n = 3 for (e)).
Despite many efforts focusing on regenerative medicine, there are few clinically-available cell-delivery carriers to improve the efficacy of cell transplantation due to the lack of adequate scaffolds. Herein, we report an injectable scaffold composed of functionalized gelatin for application in cell transplantation. Injectable functionalized gelatin-based hydrogels crosslinked with reversible hydrogen bonding based on supramolecular chemistry were designed. The hydrogel exhibited thixotropy, enabling single syringe injection of cell-encapsulating hydrogels. Highly biocompatible and cell-adhesive hydrogels provide cellular scaffolds that promote cellular adhesion, spreading, and migration. The in vivo degradation study revealed that the hydrogel gradually degraded for seven days, which may lead to prolonged retention of transplanted cells and efficient integration into host tissues. In volumetric muscle loss models of mice, cells were transplanted using hydrogels and proliferated in injured muscle tissues. Thixotropic and injectable hydrogels may serve as cell delivery scaffolds to improve graft survival in regenerative medicine.
The biodegradation rate of Mg alloy medical devices, such as screws and plates for temporary bone fracture fixation or coronary angioplasty stents, is an increasingly important area of study. In vitro models of the corrosion behavior of these devices use revised simulated body fluid (m-SBF) based on a healthy individual’s blood chemistry. Therefore, model outputs have limited application to patients with altered blood plasma glucose or protein concentrations. This work studies the biodegradation behavior of the Mg alloy, WE43, in m-SBF modified with varying concentrations of glucose and bovine serum albumin (BSA) to 1) mimic a range of disease states and 2) determine the contributions of each biomolecule to corrosion. Measurements include the Mg ion release rate, electrolyte pH, the extent of hydrogen evolution (as a proxy for corrosion rate), surface morphology, and corrosion product composition and effects. BSA (0.1 g L–1) suppresses the rate of hydrogen evolution (about 30%) after 24 h and—to a lesser degree—Mg2+ release in both the presence and absence of glucose. This effect gets more pronounced with time, possibly due to BSA adsorption on the Mg surface. Electrochemical studies confirm that adding glucose (2 g L–1) to the solution containing BSA (0.1 g L–1) caused a decrease in corrosion resistance (by around 40%), and concomitant increase in the hydrogen evolution rate (from 10.32-11.04 mg cm–2 d–1) to levels far beyond the tolerance limits of live tissues.
Organoids, and in particular patient-derived organoids, have emerged as crucial tools for cancer research. Our organoid platform, which has supported patient-derived tumor organoids (PTOs) from a variety of tumor types, has been based on the use of hyaluronic acid (HA) and collagen, or gelatin, hydrogel bioinks. One hurdle to high throughput PTO biofabrication is that as high-throughput multi-well plates, bioprinted volumes have increased risk of contacting the sides of wells. When this happens, surface tension causes bioinks to fall flat, resulting in 2D cultures. To address this problem, we developed an organoid immersion bioprinting method – inspired by the FRESH printing method – in which organoids are bioprinted into support baths in well plates. The bath – in this case an HA solution – shields organoids from the well walls, preventing deformation. Here we describe an improvement to our approach, based on rheological assessment of previous gelatin baths versus newer HA support baths, combined with morphological assessment of immersion bioprinted organoids. HA print baths enabled more consistent organoid volumes and geometries. We optimized the printing parameters of this approach using a cell line. Finally, we deployed our optimized immersion bioprinting approach into a drug screening application, using PTOs derived from glioma biospecimens, and a lung adenocarcinoma brain metastasis. In these studies, we showed a general dose dependent response to an experimental p53 activator compound and temozolomide (TMZ), the drug most commonly given to brain tumor patients. Responses to the p53 activator compound were effective across all PTO sets, while TMZ responses were observed, but less pronounced, potentially explained by genetic and epigenetic states of the originating tumors. The studies presented herein showcase a bioprinting methodology that we hope can be used in increased throughput settings to help automate biofabrication of PTOs for drug development-based screening studies and precision medicine applications.
Crystalline titanium oxides have shown photocatalytic activity (PCA) and the formation of antibacterial reactive oxygen species (ROS) when stimulated with UV light. Polyaniline (PANI) is a conductive polymer that has shown antibacterial effects. Previously, titanium oxides have been PANI-doped using a multi-step approach. In the present study, we compared PANI-doped specimens produced with a two-step method (ACV), to PANI-doped specimens produced by a novel single-step direct anodization (AAn) method, and a control group of anodized un-doped specimens. The surface morphology, oxide crystallinity, surface elemental composition, surface roughness, surface wettability, oxide adhesion, corrosion resistance, PCA, and ROS generation of each oxide group were evaluated. All groups exhibited mixed anatase and rutile phase oxides. The AAn group revealed less anatase and rutile, but more PANI-surface coverage. The AAn group exhibited significantly increased PCA after 60 minutes of direct UVA illumination compared to the ACV group, despite containing lower amounts of anatase and rutile. The ACV and AAn groups showed significant increases in ROS production after 4 hours UVA illumination while the control group showed similar ROS production. These findings suggested that PANI doping using the novel direct anodization technique significantly improved PCA even for oxides containing less crystallinity. The S. aureus attachment response to each oxide group was also compared under UVA pre-illumination, UVA direct illumination, and no illumination (dark) lighting conditions. Although no significant differences were shown in the bacterial response, both PANI-doped groups exhibited less average bacterial attachment compared to the control group. The response of MC3T3-E1 pre-osteoblast cells to each oxide group was evaluated using MTT and live/dead assays, and no evidence of cytotoxicity was found. Since many, if not most, titanium implant devices are routinely anodized as a part of the manufacturing processes, these study findings are applicable to a wide variety of implant applications.
Osteocytes are considered the primary mechanical sensor in bone tissue and orchestrate the coupled bone remodeling activity of adjacent osteoblast and osteoclast cells. In vivo investigation of mechanically induced signal propagation through networks of interconnected osteocytes is confounded by their confinement within the mineralized bone matrix, which cannot be modeled in conventional culture systems. In this study, we developed a new model that mimics this in vivo confinement using gelatin methacrylate (GelMA) hydrogel or GelMA mineralized using osteoblast-like model cells. This model also enables real-time optical examination of osteocyte calcium (Ca2+) signaling dynamics in response to fluid shear stimuli cultured under confined conditions. Using this system, we discovered several distinct and previously undescribed patterns of Ca2+ responses that vary across networks of interconnected osteocytes as a function of space, time and connectivity. Heterogeneity in Ca2+ signaling may provide new insights into bone remodeling in response to mechanical loading. Overall, such a model can be extended to study signaling dynamics within cell networks exposed to flow-induced mechanical stimuli under confined conditions.
Müller cells are the principal glial cells for the maintenance of structural stability and metabolic homeostasis in the human retina. Although various in vitro experiments using two-dimensional monolayer cell (2D) cultures have been performed, the results provided only limited results because of the lack of 3D structural environment and different cellular morphology. We studied a Müller cell-based 3D biomimetic model for use in experiments on the in vivo-like functions of Müller cells within the sensory retina. Isolated primary Müller cells were bioprinted and a 3D-aligned architecture was induced, which aligned Müller cell structure in retinal tissue. The stereographic and functional characteristics of the biomimetic model were investigated and compared to those of the conventional 2D cultured group. The results showed the potential to generate Müller cell-based biomimetic models with characteristic morphological features such as endfeet, soma, and microvilli. Especially, the 3D Müller cell model under hyperglycemic conditions showed similar responses as observed in the in vivo diabetic model with retinal changes, whereas the conventional 2D cultured group showed different cytokine and growth factor secretions. These results show that our study is a first step toward providing advanced tools to investigate the in vivo function of Müller cells and to develop complete 3D models of the vertebrate retina.
As a typical metal-organic framework (MOF), Mg-MOF74 can release biocompatible Mg2+ when the framework is degraded, and it has the potential to be used as filler in the field of bone tissue engineering (BTE). However, Mg-MOF74 has poor stability in aqueous environment and limited antibacterial ability, which limit its further development and applications. In this work,MgCu-MOF74 particles with different Cu content were synthesized through a facile one-step hydrothermal method. The physicochemical properties and water stability of the synthesized powders were characterized. The osteogenic potential of the MgCu-MOF74 particles on human osteogenic sarcoma cells (SaOS-2) was evaluated. The hybrid MgCu-MOF74 exhibited favorable water stability. These results indicated that MgCu-MOF74 enhanced cellular viability, alkaline phosphatase (ALP) levels, collagen (COL) synthesis and osteogenesis-related gene expression. Moreover, the samples doped with Cu2+ were more sensitive to the acidic microenvironment produced by bacteria, and exhibited stronger antibacterial ability than Mg-MOF74. In conclusion, MgCu-MOF-74 with good water stability, osteogenic ability and antibacterial ability, which could be attributed to the doping of Cu2+. Hence, MgCu-MOF74 shows great potential as a novel medical bio-functional fillers for the treatment of bone defects.
The demand for artificial vascular grafts in clinical applications is increasing, and it is urgent to design a tissue-engineered vascular graft with good biocompatibility and sufficient mechanical strength. In this study, three-layer small diameter artificial vascular grafts were constructed by electrospinning. Polycaprolactone (PCL) and collagen (COL) were used as the inner layer to provide good biocompatibility and cell adhesion, the middle layer was PCL to improve the mechanical properties, and gelatin (GEL) and PCL were used to construct the outer layer for further improving the mechanical properties and biocompatibility of the vascular grafts in the human body environment. The electrospun artificial vascular graft had good biocompatibility and mechanical properties. Its longitudinal maximum stress reached 2.63±0.12MPa, which exceeded the maximum stress that many natural blood vessels could withstand. The fibre diameter of the vascular grafts was related to the proportion of components that made up the vascular grafts. In the inner structure of the vascular grafts, the hydrophilicity of the vascular grafts was enhanced by the addition of COL to the PCL, and Human umbilical vein endothelial cells (HUVECs) adhered more easily to the vascular grafts. In particular, the cytocompatibility and proliferation of HUVECs on the scaffold with an inner structure PCL:COL = 2:1 was superior to other ratios of vascular grafts. The vascular grafts didn’t cause hemolysis of red blood cells. Thus, the bionic PCL-COL@PCL@PCL-GEL composite graft is a promising material for vascular tissue engineering.
Porous Nb-25Ta-25Ti alloys (60% porosity and 100-600 μm pore size) for bone implant applications were manufactured combining impregnation and sintering methods. Surfaces with porous micro-nanostructured networks on Nb-Ta-Ti alloys were successfully modified by various surface pre-treatments (acid etching, alkali-heat treatment and annealing treatment). Surface characteristics and Ca-P layer deposition behaviors of the multilevel structured porous Nb-Ta-Ti alloys were investigated by conducting various tests, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDS), atomic force microscopy (AFM) and optical contact angle measurement. In particular, bulk Nb-Ta-Ti alloys were also used as mutual control. The results demonstrated that the porous alloy exhibited a unique multilevel porous structure with macro-networks and micro-pits after pre-treatments. The surface passive TiO2/Nb2O5/Ta2O5 layers on Nb-Ta-Ti alloys were partially dissolved by the corrosive attack of hydroxyl ions during alkali heat treatment. In addition, subsequent annealing treatment increased the density of the gel layers formed during alkali heat treatment. After immersion in SBF for 14 d, a continuous relatively uniform apatite layer was formed on the multilevel structured surfaces. Moreover, the mechanism of surface mineralization can be construed as electrostatic interactions between substrates and ions. Furthermore, in vitro cell culture showed that Nb-Ta-Ti alloys had a good biocompatibility and the multilevel porous structure could enhance the cellular behaviors including: cell adhesion and spreading.
This article aims to understand the rheology of collagen networks and their role in various stages of a bioprinting process while building tissue-like constructs. The science of rheology, which deals with the deformation and flow of matter, has grown considerably from its earlier focus on polymer melts and solutions and their processing methods to hydrogels with new processing procedures, such as bioprinting. The main objective of this paper is to discuss the impact of the rheology of collagen hydrogels on micro-extrusio and layer stacking stages of bioprinting. Generally, the rheological characterization of hydrogels, including collagens by dynamic measurements under small deformations, is considered sufficient to evaluate their bioprinting performance. However, we brought out the importance of other rheological properties of collagen networks such as steady-state shear flow conditions and large amplitude oscillator shear. While the dynamic measurements under small deformations are useful for characterizing the crosslinking and gel formations of the collagen, the steady shear flow measurements are better tools for investigating filament micro-extrusion and layer-stacking stages of a bioprinting process. We brought the role of other non-Newtonian material functions, such as first normal stress difference and extensional viscosity in addition to shear viscosity, for the first time. Extensional viscosity and the viscoelasticity manifested through normal-stress differences are significant in capillary (needle) flow. We also suggested caution to use of dynamic viscosity vs. oscillation frequency under small deformations in the place of steady shear viscosity vs. shear rate measurement. In addition, we brought out the importance of the large amplitude oscillatory shear test to investigate the collagen networks under large deformations. Finally, we discussed the role of crosslinking and flow conditions on cell viability. Those discussions are focused on collagen networks; nevertheless, they are valid on the bioprinting of other hydrogels.
This study aimed to design and develop nanoscaffolds for the controlled release of memantine by non-solvent-induced phase separation (N-TIPS) method. The development and optimization of nanoscaffolds was performed by Box-Behnken Design in which two independent formulation variables and one independent process variable: Poly (lactic-co-glycolic acid) (PLGA) (X1), Pluronics F-127 (X2), and Rotation speed (X3) were used. The design provided fifteen formulation designs which were prepared to determine the response: Percentage porosity (Y1) and drug loading (Y2). Polynomial equations were generated and analyzed statistically to establish a relationship between independent and dependent variables and develop an optimal formulation with maximized porosity (%) and drug loading (%). The optimized formulation batch was prepared using 19.18% w/v PLGA, 4.98% w/v Pluronics at 500rpm rotation speed and exhibited drug loading of 11.66 % and porosity of 82.62 %. Further, correlation between the independent and dependent variables were established and statistically analysed by using model generated mathematical regression equations, ANOVA, residual plots, interaction plot, main effect plot, contour plot and response surface designs. The analysis of model showed the significant individual effect of PLGA and significant interactive effect of Pluronics F-127 and rotation speed on drug loading and porosity. Further, its physicochemical characterazation, and in-vitro (drug release kinetics, and PAMPA study), Ex-vivo (enzyme inhibition assay and pro-inflammatory cytokines study) and in-vivo (neurobehavioral and histological study) studies were performed to evaluate the potential of memantine-loaded nanoscaffolds in the treatment of Alzheimer’s disease (AD).
3D bioprinting technology has gained increased attention in the regenerative medicine and tissue engineering communities over the past decade with their attempts to create functional living tissues and organs de novo. While tissues such as skin, bone and cartilage have been successfully fabricated using 3D bioprinting, there are still many technical and process driven challenges that must be overcome before a complete tissue engineered solution is realized. Although there may never be a single adopted bioprinting process in the scientific community, adherence to optimized bioprinting protocols could reduce variability and improve precision with the goal of ensuring high quality printed constructs. Here, we report on the bioprinting of a gelatin-alginate-collagen bioink containing human mesenchymal stromal cells (hMSCs) which has been optimized to ensure printing consistency and reliability. The study consists of three phases: a pre-printing phase which focuses on bioink characterization; a printing phase which focuses on bioink extrudability/printability, construct stability, and printing accuracy; and a post-processing phase which focuses on the homogeneity and bioactivity of the encapsulated hMSC printed constructs. The results showed that eight identical constructs containing hMSCs could be reliably and accurately printed into stable cross-hatched structures with a single material preparation, and that batch-to-batch consistency was accurately maintained across all preparations. Analysis of the proliferation, morphology and differentiation of encapsulated hMSCs within the printed constructs showed that cells were able to form large, interconnected colonies and were capable of robust adipogenic differentiation within 14 days of culturing.
This study developed a biodegradable composite porous polyurethane scaffold based on polycaprolactone and polyethylene glycol by sequential in-situ foaming salt leaching and freeze-drying process with responsive shape changing performance. Biomineral hydroxyapatite (HA) was introduced into the polyurethane matrix as inorganic fillers. Infrared spectroscopy results proved a successful synthesis, scanning electron microscopy showed that the scaffold’s porosity decreased with the addition of HA while the average pore size increased. X-ray diffraction and differential scanning calorimetry showed that the addition of HA lowered the melting point of the scaffold, resulting in a transition temperature close to the human body temperature. From the bending experiments, it could be demonstrated that PUHA20 has excellent shape memory performance with shape fixity ratio >98.9% and shape recovery ratio >96.2%. Interestingly, the shape-changing capacity could be influenced by the porous structures with variation of HA content. The shape recovery speed was further accelerated when the material was immersed in phosphate buffered saline at 37 °C. Additionally, in vitro mineralization experiments showed that the scaffold incorporating HA had good osteoconductivity, and implantation assessment proved that scaffolds had good in vivo biocompatibility. This scaffold is a promising candidate for implantation of bone defects.
(a) The image of CnBs and ZnO@CnBs; SEM image of the CnBs and ZnO@CnBs; (b) degradation rate of CnBs and ZnO@CnBs. (c) The XRD patterns of ZnO@CnBs and CnBs; (d) XRD patterns of CnBs after being dispersed in SBF for different time points; (e) XRD patterns of ZnO@CnBs after being dispersed in SBF for different time points; (f) compression stress–strain curve of CnBs; (g) compression stress–strain curve of ZnO@CnBs; (h) compressive strength; (i) compressive modulus. Data are represented as mean values ± SD (n = 3). P values were calculated using Student’s t-test and Student’s t-test with Welch’s correction (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).
(a) The antibacterial activity of CnBs and ZnO@CnBs by the surface plate count method and inhibition zone antibacterial tests; The antibacterial rate of CnBs and ZnO@CnBs against S. aureus (b) and E. coli (c). Data are represented as mean values ± SD (n = 3). P values were calculated using Student’s t-test (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).
(a) Fluorescence images of live/dead cell staining of BMSCs; (b) live/dead ration of BMSCs in live/dead staining; (c) the OD value of the BMSC treated with 1:7 dilution of the extract of CnBs and 1:15 dilution of the extract of ZnO@CnBs for one, three and seven days; (d) the OD value of the BMSC treated with undiluted, 1:1, 1:3, 1: 7, 1:15 and 1:31 for 7 days. Data are represented as mean values ± SD (n = 5). P values were calculated using two-way ANOVA multiple comparisons (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).
(a) Photographs of Alkaline phosphatase staining; (b) proportion of positive areas for Alkaline phosphatase staining; (c) photographs of Alizarin Red staining for calcium nodules; (d) quantification of Alizarin Red staining for calcium nodules; (e)–(g) the expression of ALP, Runx2, and Col-1 of MC3T3-E1 cells after different time points. Data (b) and (d) are represented as mean values ± SD (n = 5), data (e)–(g) are represented as mean values ± SD (n = 3). P values were calculated using one-way ANOVA (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001).
In vivo bone regeneration test; (a) the gross images of non-treated, CnBs, ZnO@CnBs with S. aureus and CnBs with S. aureus treated for six weeks specimen; (b) x-ray image of rabbit postoperative four and six weeks. (c) The H&E staining of specimen with 20 and 200 times magnification.
The treatment of implant-associated bone infection remains a significant clinical challenge. However, bone scaffolds with antimicrobial activity and osteoinductive properties can prevent these infections and improve clinical outcomes. In this study, borosilicate bioglass and chitosan composite scaffolds were prepared, and then the surface was modified with nano-zinc oxide. In vitro and in vivo experiments showed that the chitosan/borosilicate bioglass scaffolds have good degradation and osteogenic properties, while the oxidized Zinc scaffolds have better antibacterial properties.
Objectives: This study aimed to describe the synthesis and characterization of a calcium phosphate bone cement (CPC) with polyetheretherketone/poly (lactic-co-glycolic) acid (PEEK/PLGA) micro-particles containing quercetin. Materials and methods: CPC powder was synthesized by mixing dicalcium phosphate anhydrate (DCPA) and tetracalcium phosphate (TTCP). To synthesize PEEK/PLGA microparticles, PLGA85:15 was mixed with 90wt% PEEK. The weight ratio of quercetin/PLGA/PEEK was 1:9:90%. PEEK/PLGA/quercetin microparticles with 3, 5, and 6wt% was added to CPC. The setting time, compressive strength, drug release profile, solubility, pH, and porosity of synthesized cement were evaluated. The morphology and physicochemical properties of particles was analyzed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and inductively coupled plasma (ICP). Cytotoxicity was assessed by the methyl thiazolyl tetrazolium (MTT) assay using dental pulp stem cells (DPSC). Expression of osteoblastic differentiation genes was evaluated by real-time polymerase chain reaction (real time-PCR). Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05). Results: The setting time of 3wt% CPC was significantly longer than 5 and 6wt% CPC (P<0.001). The 6wt% CPC had significantly higher compressive strength than other groups (P=0.001). The release of quercetin from CPCs increased for 5 days, and then reached a plateau. XRD and FTIR confirmed the presence of hydroxyapatite (HA) in cement composition. Significantly higher expression of osteocalcin (OCN) and osteopontin (OPN) was noted in 3wt% and 6wt% CPCs. Conclusion: Addition of quercetin-containing PEEK/PLGA microparticles to CPC enhanced its compressive strength, decreased its setting time, enabled controlled drug release, and up-regulated OPN and OCN.
Background: Calcific aortic valve disease (CAVD) is a frequent cardiac pathology in the aging society. Although valvular interstitial cells (VIC) seem to play a crucial role, mechanisms of CAVD are not fully understood. Development of tissue-engineered cellular models by 3D-bioprinting may help to further investigate underlying mechanisms of CAVD. Methods: VIC were isolated from ovine aortic valves and cultured in Dulbecco's Modified Eagle's Medium (DMEM). VIC of passages six to ten were dissolved in a hydrogel consisting of 2% alginate and 8% gelatin with a concentration of 2x106VIC/ml. Cell-free and VIC-laden hydrogels were printed with an extrusion-based 3D-bioprinter (3D-Bioplotter® Developer Series, EnvisionTec, Gladbeck, Germany), cross-linked and incubated for up to 28 days. Accuracy and durability of scaffolds was examined by microscopy and cell viability was tested by cell counting kit-8 assay and live/dead staining. Results: 3D-bioprinting of scaffolds was most accurate with a printing pressure of P<400 hPa, nozzle speed of v<20 mm/s, hydrogel temperature of TH=37 °C and platform temperature of TP=5 °C in a 90° parallel line as well as in a honeycomb pattern. Dissolving the hydrogel components in DMEM increased VIC viability on day 21 by 2.5-fold compared to regular 0.5% saline-based hydrogels (p<0.01). Examination at day 7 revealed dividing and proliferating cells. After 21 days the entire printed scaffolds were filled with proliferating cells. Live/dead cell viability/cytotoxicity staining confirmed beneficial effects of DMEM-based cell-laden VIC hydrogel scaffolds even 28 days after printing. Conclusions: By using low pressure printing methods, we were able to successfully culture cell-laden 3D-bioprinted VIC scaffolds for up to 28 days. Using DMEM-based hydrogels can significantly improve the long-term cell viability and overcome printing-related cell damage. Therefore, future applications 3D-bioprinting of VIC might enable the development of novel tissue engineered cellular 3D-models to examine mechanisms involved in initiation and progression of CAVD.
Journal metrics
Acceptance rate
22 days
Submission to first decision
4.103 (2021)
Journal Impact Factor™
1.115 (2021)
Immediacy Index
0.625 (2021)
Top-cited authors
Roshan James
  • University of Connecticut
Syam P Nukavarapu
  • UConn Health Center
Fu-Zhai Cui
  • Tsinghua University
Viness Pillay
  • University of the Witwatersrand
Yahya E. Choonara
  • University of the Witwatersrand