Fabrication and characterization of a rapid prototyped tissue engineering scaffold with embedded multicomponent matrix for controlled drug release

Histochemistry for Molecular Imaging in Nanomedicine

All the nanotechnological devices designed for medical purposes have to deal with the common requirement of facing the complexity of a living organism. Therefore, the development of these nanoconstructs must involve the study of their structural and functional interactions and the effects on cells, tissues, and organs, to ensure both effectiveness and safety. To this aim, imaging techniques proved to be extremely valuable not only to visualize the nanoparticles in the biological environment but also to detect the morphological and molecular modifications they have induced. In particular, histochemistry is a long-established science able to provide molecular information on cell and tissue components in situ, bringing together the potential of biomolecular analysis and imaging. The present review article aims at offering an overview of the various histochemical techniques used to explore the impact of novel nanoproducts as therapeutic, reconstructive and diagnostic tools on biological systems. It is evident that histochemistry has been playing a leading role in nanomedical research, being largely applied to single cells, tissue slices and even living animals.

Biomineralized tetramethylpyrazine-loaded PCL/gelatin nanofibrous membrane promotes vascularization and bone regeneration of rat cranium defects

Conventional electrospinning produces nanofibers with smooth surfaces that limit biomineralization ability. To overcome this disadvantage, we fabricated a tetramethylpyrazine (TMP)-loaded matrix-mimicking biomineralization in PCL/Gelatin composite electrospun membranes with bubble-shaped nanofibrous structures. PCL/Gelatin membranes (PG), PCL/Gelatin membranes containing biomineralized hydroxyapatite (HA) (PGH), and PCL/Gelatin membranes containing biomineralized HA and loaded TMP (PGHT) were tested. In vitro results indicated that the bubble-shaped nanofibrous surface increased the surface roughness of the nanofibers and promoted mineralization. Furthermore, sustained-release TMP had an excellent drug release efficiency. Initially released vigorously, it reached stabilization at day 7, and the slow-release rate stabilized at 61.0 ± 1.8% at 28 days. All membranes revealed an intact cytoskeleton, cell viability, and superior adhesion and proliferation when stained with Ghost Pen Cyclic Peptide, CCK-8, cell adhesion, and EdU. In PGHT membranes, the osteogenic and vascularized gene expression of BMSCs and human vascular endothelial cells was significantly upregulated compared with that in other groups, indicating the PGHT membranes exhibited an effective vascularization role. Subsequently, the membranes were implanted in a rat cranium defect model for 4 and 8 weeks. Micro-CT and histological analysis results showed that the PGHT membranes had better bone regenerative patterns. Additionally, the levels of CD31 and VEGF significantly increased in the PGHT membrane compared with those in other membranes. Thus, PGHT membranes could accelerate the repair of cranium defects in vivo via HA and TMP synergistic effects.

Fabrication of polycaprolactone electrospun fibres with retinyl acetate for antioxidant delivery in a ROS-mimicking environment

Background: Increased cancer rates denote that one in two people will be diagnosed with cancer in their lifetime. Over 60% of cancer patients receive radiotherapy, either as a stand-alone treatment or in combination with other treatments such as chemotherapy and surgery. Whilst radiotherapy is effective in destroying cancer cells, it also causes subsequent damage to healthy cells and surrounding tissue due to alterations in the tumor microenvironment and an increase in reactive oxygen species (ROS). This can cause extensive damage that impairs tissue function, and the likelihood of tissue regeneration and restoration of function is significantly reduced as new healthy cells cannot survive in the damaged environment. In the treatment of head and neck cancers, radiotherapy can cause salivary gland dysfunction. This significantly impairs the patient's quality of life and there is currently no cure, only palliative treatment options. Tissue engineering approaches are used to mimic the microenvironment of the tissue and can mediate the damaged microenvironment via bioactive compounds, to support the delivery, survival, and proliferation of new, healthy cells into the damaged environment. Methods: In this study, retinyl acetate, a derivative of vitamin A, was successfully incorporated into electrospun polycaprolactone fibres. Results: SEM images and characterization analyses showed that all scaffolds produced had similar characteristics, including fiber morphology and scaffold wettability. The vitamin scaffolds were shown to exert an antioxidant effect through scavenging activity of both DPPH and hydroxyl radicals in vitro. Critically, the antioxidant scaffolds supported the growth of human submandibular gland cells and significantly upregulated the expression of GPx1, an antioxidant enzyme, when cultured under both normal conditions and under a simulated oxidative stress environment. Discussion: These results suggest that incorporation of retinyl acetate into electrospun fibres has may mediate the damaged microenvironment post cancer radiation therapy.

Layered Clay Minerals in Cancer Therapy: Recent Progress and Prospects

Cancer is one of the deadliest diseases, and current treatment regimens suffer from limited efficacy, nonspecific toxicity, and chemoresistance. With the advantages of good biocompatibility, large specific surface area, excellent cation exchange capacity, and easy availability, clay minerals have been receiving ever-increasing interests in cancer treatment. They can act as carriers to reduce the toxic side effects of chemotherapeutic drugs, and some of their own properties can kill cancer cells, etc. Compared with other morphologies clays, layered clay minerals (LCM) have attracted more and more attention due to adjustable interlayer spacing, easier ion exchange, and stronger adsorption capacity. In this review, the structure, classification, physicochemical properties, and functionalization methods of LCM are summarized. The state-of-the-art progress of LCM in antitumor therapy is systematically described, with emphasis on the application of montmorillonite, kaolinite, and vermiculite. Furthermore, the property-function relationships of LCM are comprehensively illustrated to reveal the design principles of clay-based antitumor systems. Finally, foreseeable challenges and outlook in this field are discussed.

Application of additively manufactured 3D scaffolds for bone cancer treatment: a review

Bone cancer is a critical health problem on a global scale, and the associated huge clinical and economic burdens are still rising. Although many clinical approaches are currently used for bone cancer treatment, these methods usually affect the normal body functions and thus present significant limitations. Meanwhile, advanced materials and additive manufacturing have opened up promising avenues for the development of new strategies targeting both bone cancer treatment and post-treatment bone regeneration. This paper presents a comprehensive review of bone cancer and its current treatment methods, particularly focusing on a number of advanced strategies such as scaffolds based on advanced functional materials, drug-loaded scaffolds, and scaffolds for photothermal/magnetothermal therapy. Finally, the main research challenges and future perspectives are elaborated.

Silva AG, Fonseca MG, Silva-Filho EC. Clay Mineral Minerals as a Strategy for Biomolecule Incorporation: Amino Acids Approach

The potential use of amino acids by ruminal microorganisms converting them into microbial protein for ruminants makes it challenging to supplement these nutrients in an accessible form in animals' diets. Several strategies to protect amino acids from ruminal degradation were reported, producing amino acids available for the protein used in the intestine called "bypass." The intercalation of biomolecules in clay mineral minerals has gained notoriety due to its ability to support, protect, transport, physicochemical properties and non-toxicity. This study aimed to investigate the incorporation of L-lysine (Lys), L-methionine (Met), and L-tryptophan (Trp) amino acids in the clay minerals sepiolite (Sep) and Veegum® (Veg) using the adsorption method. The characterization techniques of X-ray diffraction and infrared spectroscopy indicated the presence of biomolecules in the inorganic matrices. Elemental and thermal analyzes monitored the percentages of incorporated amino acids. They showed better incorporation capacities for Veg, such as Met-Veg < Lys-Veg < Trp-Veg and Lys-Sep < Met-Sep < Trp-Sep for sepiolite, except for the incorporation of Met. Matrices provide a promising alternative for planning the administration of biomolecules, using essential amino acids as models, and may offer an alternative to improve functional diet strategies.

Therapeutic Applications of Halloysite

In recent years, nanomaterials have attracted significant research interest for applications in biomedicine. Many kinds of engineered nanomaterials, such as lipid nanoparticles, polymeric nanoparticles, porous nanomaterials, silica, and clay nanoparticles, have been investigated for use in drug delivery systems, regenerative medicine, and scaffolds for tissue engineering. Some of the most attractive nanoparticles for biomedical applications are nanoclays. According to their mineralogical composition, approximately 30 different nanoclays exist, and the more commonly used clays are bentonite, halloysite, kaolinite, laponite, and montmorillonite. For millennia, clay minerals have been extensively investigated for use in antidiarrhea solutions, anti-inflammatory agents, blood purification, reducing infections, and healing of stomach ulcers. This widespread use is due to their high porosity, surface properties, large surface area, excellent biocompatibility, the potential for sustained drug release, thermal and chemical stability. We begin this review by discussing the major nanoclay types and their application in biomedicine, focusing on current research areas for halloysite in biomedicine. Finally, recent trends and future directions in HNT research for biomedical application are explored.

Dual drug release mechanisms through mesoporous silica nanoparticle/electrospun nanofiber for enhanced anticancer efficiency of curcumin

Electrospun nanofibers (NFs)-based drug delivery approaches are of particular interest as a hopeful implantable nanoplatform for localized cancer therapy and treating tissue defect after resection, allowing the on-site drug delivery with minimal side effect to healthy cells. To maintain therapeutic concentrations of anticancer molecules for a relatively long time through a combination of burst and sustained drug release mechanisms, a hybrid of polycaprolactone and gelatin (PCL/GEL) was used for co-encapsulation of free curcumin (CUR) and CUR-loaded mesoporous silica nanoparticles (CUR@MSNs) via electrospinning, resulting in a novel drug-loaded nanofibrous scaffold, CUR/CUR@MSNs-NFs. The as-prepared MSNs and composite NFs were characterized via TGA, FTIR, FE-SEM, TEM, and BET. In vitro release profile of CUR from CUR/CUR@MSNs-NFs was examined, and the in vitro antitumor efficacy against MDA-MB-231 breast cancer cells was also evaluated through MTT, scratch assay, DAPI staining, and real-time PCR. The results disclosed that the smooth, bead-free, and randomly oriented CUR/CUR@MSNs-NFs displayed a combination of initial rapid discharge and sustained release for CUR, which led to higher cytotoxicity, lower migration as well as a more pronounced effect on apoptosis induction than CUR-NFs and CUR@MSNs-NFs. The present study illustrated that the dual drug release mechanisms through MSN/NF-mediated drug delivery systems might have a highly hopeful application as a localized implantable scaffold for potential postoperative breast cancer therapy.

Three-Dimensional Printing for Cancer Applications: Research Landscape and Technologies

As a variety of novel technologies, 3D printing has been considerably applied in the field of health care, including cancer treatment. With its fast prototyping nature, 3D printing could transform basic oncology discoveries to clinical use quickly, speed up and even revolutionise the whole drug discovery and development process. This literature review provides insight into the up-to-date applications of 3D printing on cancer research and treatment, from fundamental research and drug discovery to drug development and clinical applications. These include 3D printing of anticancer pharmaceutics, 3D-bioprinted cancer cell models and customised nonbiological medical devices. Finally, the challenges of 3D printing for cancer applications are elaborated, and the future of 3D-printed medical applications is envisioned.

Prolonged proliferation and delayed senescence of the adipose-derived stem cells grown on the electrospun composite nanofiber co-encapsulated with TiO2 nanoparticles and metformin-loaded mesoporous silica nanoparticles

This study was aimed to investigate the effects of the Poly-ε-Caprolactone/Gelatin nanofibers (PCL/GEL NFs) co-encapsulated with TiO₂ nanoparticles (nTiO₂) and metformin-loaded mesoporous silica nanoparticles (MET@MSNs) on prolonging the in vitro expansion of human adipose-derived stem cells (hADSCs) without inducing cellular senescence and aging. FTIR, BET, FE-SEM, and TEM were applied to characterize the fabricated MET@MSNs and electrospun composite NFs. The presence of inorganic particles, nTiO₂ and MSNs, in the scaffolds improved their mechanical properties and led to a more sustained release of MET with almost the lack of the initial burst release from nTiO₂/MET@MSNs-loaded NFs. The enhanced adhesion, metabolic activity, and proliferation rate of the hADSCs grown on nTiO₂/MET@MSNs-loaded NFs were demonstrated via FE-SEM images, MTT test and PicoGreen assay, respectively, over 28 days of culture. Furthermore, the irregular nanofibrillar structures and the impact of sustained release of MET led to a significant upregulation in the mRNA levels of autophagy (Atg-5, Atg-7, Atg-12, and Beclin-1) and stemness (Nanog3, Sox-2, and Oct-4) markers as well as a considerable down-regulation of p16^INK4A senescence marker. Further, the upregulation of hTERT, enhanced activity of telomerase, and increased telomere length were more pronounced in the hADSCs cultured on nTiO₂/MET@MSNs-loaded NFs as compared to other types of NFs. Overall, our findings demonstrated the potential of the fabricated nanocomposite platform for counteracting cellular senescence and achieving sufficient quantities of fresh hADSCs with preserved stemness for various stem cell-based regenerative medicine purposes.

Exploration of Bioengineered Scaffolds Composed of Thermo-Responsive Polymers for Drug Delivery in Wound Healing

Innate and adaptive immune responses lead to wound healing by regulating a complex series of events promoting cellular cross-talk. An inflammatory response is presented with its characteristic clinical symptoms: heat, pain, redness, and swelling. Some smart thermo-responsive polymers like chitosan, polyvinylpyrrolidone, alginate, and poly(ε-caprolactone) can be used to create biocompatible and biodegradable scaffolds. These processed thermo-responsive biomaterials possess 3D architectures similar to human structures, providing physical support for cell growth and tissue regeneration. Furthermore, these structures are used as novel drug delivery systems. Locally heated tumors above the polymer lower the critical solution temperature and can induce its conversion into a hydrophobic form by an entropy-driven process, enhancing drug release. When the thermal stimulus is gone, drug release is reduced due to the swelling of the material. As a result, these systems can contribute to the wound healing process in accelerating tissue healing, avoiding large scar tissue, regulating the inflammatory response, and protecting from bacterial infections. This paper integrates the relevant reported contributions of bioengineered scaffolds composed of smart thermo-responsive polymers for drug delivery applications in wound healing. Therefore, we present a comprehensive review that aims to demonstrate these systems' capacity to provide spatially and temporally controlled release strategies for one or more drugs used in wound healing. In this sense, the novel manufacturing techniques of 3D printing and electrospinning are explored for the tuning of their physicochemical properties to adjust therapies according to patient convenience and reduce drug toxicity and side effects.

Sustainable drug release from highly porous and architecturally engineered composite scaffolds prepared by 3D printing

Additive manufacturing techniques have evolved novel opportunities for the fabrication of highly porous composite scaffolds with well-controlled and interconnected pore structures which is notably important for tissue engineering. In this work, poly (ε-caprolactone) (PCL)-based composite scaffolds (average pore diameter of 450 μm and strut thickness of 400 μm) reinforced with 10 vol% bioactive glass particles (BG; ∼6 μm) or TiO₂ nanoparticles (∼21 nm), containing different concentrations of tetracycline hydrochloride (TCH) as an antimicrobial agent, were prepared by 3D printing. In order to investigate the effect of fabrication process and scaffold geometry on the biocompatibility, drug release kinetics, and antibacterial activity, polymer and composite films (2D structures) were also prepared by solvent casting method. We demonstrate that even without any additional coating layer, sustainable release can be attained on highly porous scaffolds prepared by 3D printing due to chemical interactions between functional groups of TCH and the bioactive particles. Herein, the effect of TiO₂ nanoparticles on the release rate is substantially more pronounced than BG particles. Nevertheless, agar well-diffusion and MTT assays determine better cellular viability and higher antibacterial effect for PCL/BG composite. Although all the drug-eluting composite scaffolds exhibit acceptable hemocompatibility, in vitro cellular and bacterial studies also determine that the maximum amount of TCH that can inhibit gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria without cytotoxicity effect (≥95% viability) is 0.57 mg/ml. These findings may pave the way for designing structurally engineered composite scaffolds with sustainable drug release profile by additive manufacturing techniques for tissue engineering applications.

Anti-Tumor Effects of Low Dose Zoledronate on Lung Cancer-Induced Spine Metastasis

Zoledronate (Zol) is an anti-resorptive/tumoral agent used for the treatment of many cancers including spinal bone metastasis. High systemic administration of a single dose is now the standard clinical care, yet it has been associated with several side effects. Here, we aimed to evaluate the effects of lower doses Zol on lung cancer and lung cancer-induced bone metastasis cells over a longer time period. Human lung cancer (HCC827) and three bone metastases secondary to lung cancer (BML1, BML3 and BML4) cells were treated with Zol at 1, 3 and 10 µM for 7 days and then assessed for cell proliferation, migration, invasion and apoptosis. Low Zol treatment significantly decreased cell proliferation (1, 3 and 10 µM), migration (3 and 10 µM) and invasion (10 µM) while increasing apoptosis (10 µM) in lung cancer and metastatic cells. Our data exploits the potential of using low doses Zol for longer treatment periods and reinforces this approach as a new therapeutic regimen to impede the development of metastatic bone cancer while limiting severe side effects following high doses of systemic drug treatment.

Biomechanical evaluation of annulus fibrosus repair with scaffold and soft anchors in an ex vivo porcine model

Introduction: Altered biomechanical properties, due to intervertebral disc (IVD) degeneration and missing nucleus fibrosus, could be thought as one of the reasons for the back pain many herniation patients experience after surgery. It has been suggested to repair annulus fibrosus (AF) to restore stability and allow nucleus pulposus (NP) replacement and furthermore prevent reherniation. The aim of this study was to evaluate a new method for closing a defect in AF for use in herniation surgery.

Methods: Our repair method combines a polycaprolactone (PCL) scaffold plugging herniation and soft anchors to secure the plug. Ex vivo biomechanical testing was carried out in nine porcine lumbar motion segments. Flexion–extension, lateral bending and rotation were repeated three times: first in healthy specimens, second with a full thickness circular defect applied, and third time with the specimens repaired. Finally push out tests were performed to check whether the plug would remain in.

Results: Tests showed that applying a defect to the AF increases the range of motion (ROM), neutral zone (NZ) and neutral zone stiffness (NZS). In flexion/extension it was found significant for ROM, NZ, and NZS. For lateral bending and rotation a significant increase in ROM occurred. After AF repair ROM, NZ and NZS were normalized. All plugs remained in the AF during push out test up until 4000 N, but NP was squeezed out through the pores of the scaffold.

Discussion: A defect in the AF changes the biomechanical properties in the motion segment, changes that point to instability. Repairing the defect with a PCL plug and soft anchors brought the biomechanical behavior back to native state. This concept is promising and might be a viable way to repair the IVD after surgery.

Nanoporous 3D-Printed Scaffolds for Local Doxorubicin Delivery in Bone Metastases Secondary to Prostate Cancer

The spine is the most common site of bone metastasis, often originating from prostate, lung, and breast cancers. High systemic doses of chemotherapeutics such as doxorubicin (DOX), cisplatin, or paclitaxel often have severe side effects. Surgical removal of spine metastases also leaves large defects which cannot spontaneously heal and require bone grafting. To circumvent these issues, we designed an approach for local chemotherapeutic delivery within 3D-printed scaffolds which could also potentially serve as a bone substitute. Direct treatment of prostate cancer cell line LAPC4 and patient derived spine metastases cells with 0.01 µM DOX significantly reduced metabolic activity, proliferation, migration, and spheroid growth. We then assessed uptake and release of DOX in a series of porous 3D-printed scaffolds on LAPC4 cells as well as patient-derived spine metastases cells. Over seven days, 60–75% of DOX loaded onto scaffolds could be released, which significantly reduced metabolic activity and proliferation of both LAPC4 and patient derived cells, while unloaded scaffolds had no effect. Porous 3D-printed scaffolds may provide a novel and inexpensive approach to locally deliver chemotherapeutics in a patient-specific manner at tumor resection sites. With a composite design to enhance strength and promote sustained drug release, the scaffolds could reduce systemic negative effects, enhance bone repair, and improve patient outcomes.

Decellularized Hydrogels in Bone Tissue Engineering: A Topical Review

Nowadays, autograft and allograft techniques represent the main solution to improve bone repair. Unfortunately, autograft technique is expensive, invasive and subject to infections and hematoma, frequently affecting both donor sites and surgical sites. A recent advance in tissue engineering is the fabrication of cell-laden hydrogels with custom-made geometry, depending on the clinical case. The use of ECM (Extra-Cellular Matrix)-derived Hydrogels from bone tissue is the new opportunity to obtain good results in bone regeneration. Several micro-engineering techniques and approaches are available to fabricate different cell gradients and zonal structures in hydrogels design, in combination with the advancement in biomaterials selection. In this review, we analyse the stereolithografy, the Bio-patterning, the 3D bioprinting and 3D assembly, the Laser-Induced Forward Transfer Bioprinting (LIFT), the Micro-extrusion bioprinting, the promising Electrospinning technology, the Microfluidics and the Micromolding. Several mechanical properties are taken into account for bone regeneration scaffolds. However, each typology of scaffold presents some advantages and some concerns. The research on biomaterials is the most promising for bone tissue engineering: the new biomimetic materials will allow us to obtain optimal results in the next clinical application of basic research.

Therapeutic PCL scaffold for reparation of resected osteosarcoma defect

Osteosarcomas are highly malignant tumors, which develop rapid growth and local infiltration, inducing metastases that spread primarily in the lung. Treatment of these tumors is mainly based on pre- and post-operative chemotherapy and surgery of the primary tumor. Surgical resection though, generates bone defects. Reparation of these weaknesses presents formidable challenges to orthopedic surgery. Medicine regenerative grafts that act as both tumor therapy with constant local drug delivery and tissue regeneration may provide a new prospect to address this need. These implants can provide sustained drug release at the cancer area, decreasing systemic second effects such as inflammation, and a filling of the resected tissues with regenerative biomaterials. In this study microporous poly-ε-caprolactone (PCL) scaffolds have been developed for sustained local release of anti-inflammatory drug dexamethasone (DXM), used as drug model, in cancer medicine regenerative field. The microporous PCL matrix of the scaffolds supported the attachment, proliferation and osteogenic differentiation of osteoblast-like cells, while the polyelectrolyte multilayers, anchored to the inner pore surfaces, sustained locally DXM release. These microporous scaffolds demonstrate the ability to deliver DXM as a localized tumor therapy and to promote proliferation and differentiation of osteoblast-like cells in vitro.

Gradients in pore size enhance the osteogenic differentiation of human mesenchymal stromal cells in three-dimensional scaffolds

Small fractures in bone tissue can heal by themselves, but in case of larger defects current therapies are not completely successful due to several drawbacks. A possible strategy relies on the combination of additive manufactured polymeric scaffolds and human mesenchymal stromal cells (hMSCs). The architecture of bone tissue is characterized by a structural gradient. Long bones display a structural gradient in the radial direction, while flat bones in the axial direction. Such gradient presents a variation in bone density from the cancellous bone to the cortical bone. Therefore, scaffolds presenting a gradient in porosity could be ideal candidates to improve bone tissue regeneration. In this study, we present a construct with a discrete gradient in pore size and characterize its ability to further support the osteogenic differentiation of hMSCs. Furthermore, we studied the behaviour of hMSCs within the different compartments of the gradient scaffolds, showing a correlation between osteogenic differentiation and ECM mineralization, and pore dimensions. Alkaline phosphatase activity and calcium content increased with increasing pore dimensions. Our results indicate that designing structural porosity gradients may be an appealing strategy to support gradual osteogenic differentiation of adult stem cells.

In vivo drug release behavior and osseointegration of a doxorubicin-loaded tissue-engineered scaffold

This pre-clinical study presented a dual function of a doxorubicin-loaded scaffold for both chemotherapeutic agent delivery and bone formation.

Additive manufacturing of scaffolds with dexamethasone controlled release for enhanced bone regeneration

The adoption of additive manufacturing in tissue engineering and regenerative medicine (TERM) strategies greatly relies on the development of novel 3D printable materials with advanced properties. In this work we have developed a material for bone TERM applications with tunable bioerosion rate and dexamethasone release profile which can be further employed in fused deposition modelling (the most common and accessible 3D printing technology in the market). The developed material consisted of a blend of poly-ϵ-caprolactone (PCL) and poloxamine (Tetronic®) and was processed into a ready-to-use filament form by means of a simplified melt-based methodology, therefore eliminating the utilization of solvents. 3D scaffolds composed of various blend formulations were additively manufactured and analyzed revealing blend ratio-specific degradation rates and dexamethasone release profiles. Furthermore, in vitro culture studies revealed a similar blend ratio-specific trend concerning the osteoinductive activity of the fabricated scaffolds when these were seeded and cultured with human mesenchymal stem cells. The developed material enables to specifically address different regenerative requirements found in various tissue defects. The versatility of such strategy is further increased by the ability of additive manufacturing to accurately fabricate implants matching any given defect geometry.

A tissue-engineered therapeutic device inhibits tumor growth in vitro and in vivo

Bone metastasis is one of the leading causes of death in breast cancer patients. The current treatment is performed as a palliative therapy and the adverse side effects can compromise the patients' quality of life. In order to both effectively treat bone metastasis and avoid the limitation of current strategies, we have invented a drug eluting scaffold with clay matrix release doxorubicin (DESCLAYMR_DOX) to mechanically support the structure after resecting the metastatic tissue while also releasing the anticancer drug doxorubicin which supplements growth inhibition and elimination of the remaining tumor cells. We have previously demonstrated that this device has the capacity to regenerate the bone and provide sustained release of the anticancer drug in vitro. In this study, we focus on the ability of the device to inhibit cancer cell growth in vitro as well as in vivo. Drug-release kinetics was investigated and the cell viability test showed that the tumor inhibitory effect is sustained for up to 4weeks in vitro. Subcutaneous implantation of DESCLAYMR_DOX in athymic mice resulted in significant growth inhibition of human tumor xenografts of breast origin and decelerated multi-organ metastasis formation. Fluorescence images, visualizing doxorubicin, showed a sustained drug release from the DESCLAYMR device in vivo. Furthermore, local use of DESCLAYMR_DOX implantation reduced the incidence of doxorubicin's cardio-toxicity. These results suggest that DESCLAYMR_DOX can be used in reconstructive surgery to support the structure after bone tumor resection and facilitate a sustained release of anticancer drugs in order to prevent tumor recurrence.

Target specific delivery of anticancer drug in silk fibroin based 3D distribution model of bone-breast cancer cells

To avoid the indiscriminating action of anticancer drugs, the cancer cell specific targeting of drug molecule becomes a preferred choice for the treatment. The successful screening of the drug molecules in 2D culture system requires further validation. The failure of target specific drug in animal model raises the issue of creating a platform in between the in vitro (2D) and in vivo animal testing. The metastatic breast cancer cells migrate and settle at different sites such as bone tissue. This work evaluates the in vitro 3D model of the breast cancer and bone cells to understand the cellular interactions in the presence of a targeted anticancer drug delivery system. The silk fibroin based cytocompatible 3D scaffold is used as in vitro 3D distribution model. Human breast adenocarcinoma and osteoblast like cells are cocultured to evaluate the efficiency of doxorubicin loaded folic acid conjugated silk fibroin nanoparticle as drug delivery system. Decreasing population of the cancer cells, which lower the levels of vascular endothelial growth factors, glucose consumption, and lactate production are observed in the drug treated coculture constructs. The drug treated constructs do not show any major impact on bone mineralization. The diminished expression of osteogenic markers such as osteocalcein and alkaline phosphatase are recorded. The result indicates that this type of silk based 3D in vitro coculture model may be utilized as a bridge between the traditional 2D and animal model system to evaluate the new drug molecule (s) or to reassay the known drug molecules or to develop target specific drug in cancer research.

Three-dimensionally plotted MBG/PHBHHx composite scaffold for antitubercular drug delivery and tissue regeneration

A suitable drug-loaded scaffold that can postoperatively release an antituberculosis drug efficiently in a lesion area and help repair a bone defect is very important in the clinical treatment of bone tuberculosis (TB). In this study, a composite drug-loaded cylindrical scaffold was prepared by using three-dimensional printing technology in combination with the mesoporous confinement range, surface chemical groups, and gradual degradation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). This achieves the slow release of a drug for as long as possible. We implanted the drug-loaded compound scaffold into New Zealand rabbits' femur defect model to study the in vivo drug release performance and osteogenic ability. The in vivo release of isoniazid and rifampicin from the prepared composites could be effectively sustained for 12 weeks in local tissues, whereas these drugs were sustained for just 2 weeks in a control group. The blood drug concentrations were very low and most concentrations were below 5 μg/ml. Therefore, the systemic toxic adverse effect is very low. In addition, the composite exhibits good osteogenic potential in a rabbit bone defect model. The results of this study indicate that this composite has great potential for treating osteoarticular TB.

Co-delivery of siRNA and doxorubicin to cancer cells from additively manufactured implants

Tumors in load bearing bones are a major clinical problem as recurrence is common after surgery. Void filling scaffolds that kill residual cancer cells by releasing chemotherapy and siRNA/chitosan nanoparticles may offer a solution to this problem.

Adsorption, aggregation, and desorption of proteins on smectite particles

We report on adsorption of lysozyme (LYS), ovalbumin (OVA), or ovotransferrin (OVT) on particles of a synthetic smectite (synthetic layered aluminosilicate). In our approach we used atomic force microscopy (AFM) and quartz crystal microbalance (QCM) to study the protein-smectite systems in water solutions at pH ranging from 4 to 9. The AFM provided insights into the adhesion forces of protein molecules to the smectite particles, while the QCM measurements yielded information about the amounts of the adsorbed proteins, changes in their structure, and conditions of desorption. The binding of the proteins to the smectite surface was driven mainly by electrostatic interactions, and hence properties of the adsorbed layers were controlled by pH. At high pH values a change in orientation of the adsorbed LYS molecules and a collapse or desorption of OVA layer were observed. Lowering pH to the value ≤ 4 caused LYS to desorb and swelling the adsorbed OVA. The stability of OVT-smectite complexes was found the lowest. OVT revealed a tendency to desorb from the smectite surface at all investigated pH. The minimum desorption rate was observed at pH close to the isoelectric point of the protein, which suggests that nonspecific interactions between OVT and smectite particles significantly contribute to the stability of these complexes.

Nano/microfibrous polymeric constructs loaded with bioactive agents and designed for tissue engineering applications: a review

Nano/microfibrous polymeric constructs present various inherent advantages, such as highly porous architecture and high surface to volume ratio, making them attractive for tissue engineering purposes. Electrospinning is the most preferred technique for the fabrication of polymeric nanofibrous assemblies that can mimic the physical functions of native extracellular matrix greatly favoring cells attachment and thus influencing their morphology and activities. Different approaches have been developed to apply polymeric microfiber fabrication techniques (e.g. wet-spinning) for the obtainment of scaffolds with a three-dimensional network of micropores suitable for effective cells migration. Progress in additive manufacturing technology has led to the development of complex scaffold's shapes and microfibrous structures with a high degree of automation, good accuracy and reproducibility. Various loading methods, such as direct blending, coaxial electrospinning and microparticles incorporation, are enabling to develop customized strategies for the biofunctionalization of nano/microfibrous scaffolds with a tailored kinetics of release of different bioactive agents, ranging from small molecules, such as antibiotics, to protein drugs, such as growth factors, and even cells. Recent activities on the combination of different processing techniques and loading methods for the obtainment of biofunctionalized polymeric constructs with a complex multiscale structure open new possibilities for the development of biomimetic scaffolds endowed with a hierarchical architecture and a sophisticated release kinetics of different bioactive agents. This review is aimed at summarizing current advances in technologies and methods for manufacturing nano/microfibrous polymeric constructs suitable as tissue engineering scaffolds, and for their combination with different bioactive agents to promote tissue regeneration and therapeutic effects.

Particle Lithography Enables Fabrication of Multicomponent Nanostructures

Multicomponent nanostructures with individual geometries have attracted much attention because of their potential to carry out multiple functions synergistically. The current work reports a simple method using particle lithography to fabricate multicomponent nanostructures of metals, proteins, and organosiloxane molecules, each with its own geometry. Particle lithography is well-known for its capability to produce arrays of triangular-shaped nanostructures with novel optical properties. This paper extends the capability of particle lithography by combining a particle template in conjunction with surface chemistry to produce multicomponent nanostructures. The advantages and limitations of this approach will also be addressed.

Clay: new opportunities for tissue regeneration and biomaterial design

Seminal recent studies that have shed new light on the remarkable properties of clay interactions suggest unexplored opportunities for biomaterial design and regenerative medicine. Here, recent conceptual and technological developments in the science of clay interactions with biomolecules, polymers, and cells are examined, focusing on the implications for tissue engineering and regenerative strategies. Pioneering studies demonstrating the utility of clay for drug-delivery and scaffold design are reviewed and areas for future research and development highlighted.

Composite polymer-bioceramic scaffolds with drug delivery capability for bone tissue engineering

INTRODUCTION

Next-generation scaffolds for bone tissue engineering (BTE) should exhibit the appropriate combination of mechanical support and morphological guidance for cell proliferation and attachment while at the same time serving as matrices for sustained delivery of therapeutic drugs and/or biomolecular signals, such as growth factors. Drug delivery from BTE scaffolds to induce the formation of functional tissues, which may need to vary temporally and spatially, represents a versatile approach to manipulating the local environment for directing cell function and/or to treat common bone diseases or local infection. In addition, drug delivery from BTE is proposed to either increase the expression of tissue inductive factors or to block the expression of others factors that could inhibit bone tissue formation. Composite scaffolds which combine biopolymers and bioactive ceramics in mechanically competent 3D structures, including also organic-inorganic hybrids, are being widely developed for BTE, where the affinity and interaction between biomaterials and therapeutic drugs or biomolecular signals play a decisive role in controlling the release rate.

AREAS COVERED

This review covers current developments and applications of 3D composite scaffolds for BTE which exhibit the added capability of controlled delivery of therapeutic drugs or growth factors. A summary of drugs and biomolecules incorporated in composite scaffolds and approaches developed to combine biopolymers and bioceramics in composites for drug delivery systems for BTE is presented. Special attention is given to identify the main challenges and unmet needs of current designs and technologies for developing such multifunctional 3D composite scaffolds for BTE.

EXPERT OPINION

One of the major challenges for developing composite scaffolds for BTE is the incorporation of a drug delivery function of sufficient complexity to be able to induce the release patterns that may be necessary for effective osseointegration, vascularization and bone regeneration. Loading 3D scaffolds with different biomolecular agents should produce a codelivery system with different, predetermined release profiles. It is also envisaged that the number of relevant bioactive agents that can be loaded onto scaffolds will be increased, whilst the composite scaffold design should exploit synergistically the different degradation profiles of the organic and inorganic components.