Development of a heat labile antibiotic eluting 3D printed scaffold for the treatment of osteomyelitis

Fabrication of a 3D Corneal Model Using Collagen Bioink and Human Corneal Stromal Cells

Corneal transplantation remains a critical treatment option for individuals with corneal disorders, but it faces challenges such as rejection, high associated medical costs, and donor scarcity. A promising alternative for corneal replacement involves fabricating artificial cornea from a patient's own cells. Our study aimed to leverage bioprinting to develop a corneal model using human corneal stromal cells embedded in a collagen-based bioink. We generated both cellular and acellular collagen I (COL I) constructs. Cellular constructs were cultured for up to 4 weeks, and gene expression analysis was performed to assess extracellular matrix (ECM) remodeling and fibrotic markers. Our results demonstrated a significant decrease in the expression of COL I, collagen III (COL III), vimentin (VIM), and vinculin (VCL), indicating a dynamic remodeling process towards a more physiologically relevant corneal ECM. Overall, our study provides a foundational framework for developing customizable, corneal replacements using bioprinting technology. Further research is necessary to optimize the bioink composition and evaluate the functional and biomechanical properties of these bioengineered corneas.

The art of biodegradable polymer design for the treatments against osteomyelitis

Osteomyelitis arises from the incomplete treatment of the external wounds in the healing process, while bacterial infections persist within the bone marrow, leading to abscess formation. Osteomyelitis treatments generally involve three main aspects: rapid bactericidal action, sustained bacteriostasis, and induction of bone regeneration. However, current treatment methods, which often combine surgical debridement with long-term high-dose intravenous antibiotic administration or poly(methyl methacrylate) (PMMA) beads antibiotic therapy, suffer from significant drawbacks and limitations. In an era focused on environmental protection and sustainability, there is potential for biodegradable polymers to replace non-degradable plastic materials to reduce environmental pollution and achieve sustainable development in resources, society, and the economy. With this in mind, this review aims to explore the concept and design of applying various natural biodegradable polymers like gelatin, chitosan, cellulose, etc., and synthetic biodegradable polymers like polylactic acid, poly(lactic-co-glycolic) acid, polycaprolactone, etc. for osteomyelitis treatment, including (1) replacing PMMA with biodegradable polymer beads, (2) biodegradable polymer coatings on medical implants, (3) injectable biodegradable polymer hydrogels, and (4) biodegradable polymers as scaffolds for osteogenic cell growth. This article contributes to understanding and advancing biodegradable polymer applications in biomedicine through a comprehensive review and discussion of these four aspects.

Engineering of Bioresorbable Polymers for Tissue Engineering and Drug Delivery Applications

Herein, the recent advances in the development of resorbable polymeric-based biomaterials, their geometrical forms, resorption mechanisms, and their capabilities in various biomedical applications are critically reviewed. A comprehensive discussion of the engineering approaches for the fabrication of polymeric resorbable scaffolds for tissue engineering, drug delivery, surgical, cardiological, aesthetical, dental and cardiovascular applications, are also explained. Furthermore, to understand the internal structures of resorbable scaffolds, representative studies of their evaluation by medical imaging techniques, e.g., cardiac computer tomography, are succinctly highlighted. This approach provides crucial clinical insights which help to improve the materials' suitable and viable characteristics for them to meet the highly restrictive medical requirements. Finally, the aspects of the legal regulations and the associated challenges in translating research into desirable clinical and marketable materials of polymeric-based formulations, are presented.

Design and fabrication of customizable microneedles enabled by 3D printing for biomedical applications

Microneedles (MNs) is an emerging technology that employs needles ranging from 10 to 1000 μm in height, as a minimally invasive technique for various procedures such as therapeutics, disease monitoring and diagnostics. The commonly used method of fabrication, micromolding, has the advantage of scalability, however, micromolding is unable to achieve rapid customizability in dimensions, geometries and architectures, which are the pivotal factors determining the functionality and efficacy of the MNs. 3D printing offers a promising alternative by enabling MN fabrication with high dimensional accuracy required for precise applications, leading to improved performance. Furthermore, enabled by its customizability and one-step process, there is propitious potential for growth for 3D-printed MNs especially in the field of personalized and on-demand medical devices. This review provides an overview of considerations for the key parameters in designing MNs, an introduction on the various 3D-printing techniques for fabricating this new generation of MNs, as well as highlighting the advancements in biomedical applications facilitated by 3D-printed MNs. Lastly, we offer some insights into the future prospects of 3D-printed MNs, specifically its progress towards translation and entry into market.

A Nanoporous 3D-Printed Scaffold for Local Antibiotic Delivery

Limitations of bone defect reconstruction include poor bone healing and osteointegration with acrylic cements, lack of strength with bone putty/paste, and poor osteointegration. Tissue engineering aims to bridge these gaps through the use of bioactive implants. However, there is often a risk of infection and biofilm formation associated with orthopedic implants, which may develop anti-microbial resistance. To promote bone repair while also locally delivering therapeutics, 3D-printed implants serve as a suitable alternative. Soft, nanoporous 3D-printed filaments made from a thermoplastic polyurethane and polyvinyl alcohol blend, LAY-FOMM and LAY-FELT, have shown promise for drug delivery and orthopedic applications. Here, we compare 3D printability and sustained antibiotic release kinetics from two types of commercial 3D-printed porous filaments suitable for bone tissue engineering applications. We found that both LAY-FOMM and LAY-FELT could be consistently printed into scaffolds for drug delivery. Further, the materials could sustainably release Tetracycline over 3 days, independent of material type and infill geometry. The drug-loaded materials did not show any cytotoxicity when cultured with primary human fibroblasts. We conclude that both LAY-FOMM and LAY-FELT 3D-printed scaffolds are suitable devices for local antibiotic delivery applications, and they may have potential applications to prophylactically reduce infections in orthopedic reconstruction surgery.

Research progress on biodegradable polymeric platforms for targeting antibiotics to the bone

The treatment of bone infections still involves systemic or local antibiotic therapy in high doses for prolonged periods. Current research focuses on the application of different drug delivery systems to the bone, aiming at a targeted local administration that will decrease the number of drugs used and their toxicity, compared to the systemic route. The gold standard in clinical practice is currently poly(methyl methacrylate) (PMMA) cement. The main drawback of PMMA, however, is that it is non-biodegradable, requiring a second follow-up surgery to remove the implant. Biodegradable delivery systems, on the other hand, are easily resorbable within the organism, and less invasive alternative with better patient compliance. Among biodegradable materials, natural and synthetic polymers are being studied as local drug delivery systems due to their excellent biocompatibility, sustained effect, and antibiotic release with high penetrability to infected bone and soft tissue. In this review, we focus on biodegradable polymeric platforms, such as micro- and nanoparticles, scaffolds, and hydrogels, as well as multi-delivery systems for targeting antibiotics to the bone. Additionally, we discuss the reported drug release profiles that provide important information about the systems' functionality.

Optimization Method to Predict Optimal Noise Reduction Parameters for the Non-Local Means Algorithm Based on the Scintillator Thickness in Radiography

The resulting image obtained from an X-ray imaging system depends significantly on the characteristics of the detector. In particular, when an X-ray image is acquired by thinning the detector, a relatively large amount of noise inevitably occurs. In addition, when a thick detector is used to reduce noise in X-ray images, blurring increases and the ability to distinguish target areas deteriorates. In this study, we aimed to derive the optimal X-ray image quality by deriving the optimal noise reduction parameters based on the non-local means (NLM) algorithm. The detectors used were of two thicknesses (96 and 140 μm), and images were acquired based on the IEC 62220-1-1:2015 RQA-5 protocol. The optimal parameters were derived by calculating the edge preservation index and signal-to-noise ratio according to the sigma value of the NLM algorithm. As a result, a sigma value of the optimized NLM algorithm (0.01) was derived, and this algorithm was applied to a relatively thin X-ray detector system to obtain appropriate noise level and spatial resolution data. The no-reference-based blind/referenceless image spatial quality evaluator value, which analyzes the overall image quality, was best when using the proposed method. In conclusion, we propose an optimized NLM algorithm based on a new method that can overcome the noise amplification problem in thin X-ray detector systems and is expected to be applied in various photon imaging fields in the future.

A spatiotemporal drug release scaffold with antibiosis and bone regeneration for osteomyelitis

INTRODUCTION

Scaffolds loaded with antibacterial agents and osteogenic drugs are considered essential tools for repairing bone defects caused by osteomyelitis. However, the simultaneous release of two drugs leads to premature osteogenesis and subsequent sequestrum formation in the pathological situation of unthorough antibiosis.

OBJECTIVES

In this study, a spatiotemporal drug-release polydopamine-functionalized mesoporous silicon nanoparticle (MSN) core/shell drug delivery system loaded with antibacterial silver (Ag) nanoparticles and osteogenic dexamethasone (Dex) was constructed and introduced into a poly-l-lactic acid (PLLA) scaffold for osteomyelitis therapy.

METHODS

MSNs formed the inner core and were loaded with Dex through electrostatic adsorption (MSNs@Dex), and then polydopamine was used to seal the core through the self-assembly of dopamine as the outer shell (pMSNs@Dex). Ag nanoparticles were embedded in the polydopamine shell via an in situ growth technique. Finally, the Ag-pMSNs@Dex nanoparticles were introduced into PLLA scaffolds (Ag-pMSNs@Dex/PLLA) constructed by selective laser sintering (SLS).

RESULTS

The Ag-pMSNs@Dex/PLLA scaffold released Ag+ at the 12th hour, followed by the release of Dex starting on the fifth day. The experiments verified that the scaffold had excellent antibacterial performance against Escherichia coli and Staphylococcus aureus. Moreover, the scaffold significantly enhanced the osteogenic differentiation of mouse bone marrow mesenchymal stem cells.

CONCLUSION

The findings suggested that this spatiotemporal drug release scaffold had promising potential for osteomyelitis therapy.

Customized Additive Manufacturing in Bone Scaffolds-The Gateway to Precise Bone Defect Treatment

In the advancing landscape of technology and novel material development, additive manufacturing (AM) is steadily making strides within the biomedical sector. Moving away from traditional, one-size-fits-all implant solutions, the advent of AM technology allows for patient-specific scaffolds that could improve integration and enhance wound healing. These scaffolds, meticulously designed with a myriad of geometries, mechanical properties, and biological responses, are made possible through the vast selection of materials and fabrication methods at our disposal. Recognizing the importance of precision in the treatment of bone defects, which display variability from macroscopic to microscopic scales in each case, a tailored treatment strategy is required. A patient-specific AM bone scaffold perfectly addresses this necessity. This review elucidates the pivotal role that customized AM bone scaffolds play in bone defect treatment, while offering comprehensive guidelines for their customization. This includes aspects such as bone defect imaging, material selection, topography design, and fabrication methodology. Additionally, we propose a cooperative model involving the patient, clinician, and engineer, thereby underscoring the interdisciplinary approach necessary for the effective design and clinical application of these customized AM bone scaffolds. This collaboration promises to usher in a new era of bioactive medical materials, responsive to individualized needs and capable of pushing boundaries in personalized medicine beyond those set by traditional medical materials.

3D-Printed Capsaicin-Loaded Injectable Implants for Targeted Delivery in Obese Patients

Diet-induced obesity and hyperlipidemia are a growing public health concern leading to various metabolic disorders. Capsaicin, a major bioactive compound obtained from natural chili peppers, has demonstrated its numerous beneficial roles in treating obesity and weight loss. Current treatment involves either administration of antiobesity drugs or surgical procedures such as Roux-en-Y-gastric bypass or sleeve gastrectomy, both of which are associated with serious side effects and poor patient acceptance. Capsaicin, a pungent molecule, has low oral bioavailability. Therefore, there is a need for the development of site-specific drug delivery system for capsaicin. The present study is aimed at preparing and characterizing 3D-printed capsaicin-loaded rod-shaped implants by thermoplastic extrusion-based 3D printing technology. The implants were printed with capsaicin-loaded into a biodegradable polymer, polycaprolactone, at different drug loadings and infill densities. The surface morphology revealed a smooth and uniform external surface without any capsaicin crystals. DSC thermograms showed no significant changes/exothermic events among the blends suggesting no drug polymer interactions. The in vitro release studies showed a biphasic release profile for capsaicin, and the release was sustained for more than three months (~ 85% released) irrespective of drug loading and infill densities. The HPLC method was stability-indicating and showed good resolution for its analogs, dihydrocapsaicin and nordihydrocapsaicin. The implants were stable for three months at accelerated conditions (40°C) without any significant decrease in the assay of capsaicin. Therefore, capsaicin-loaded implants can serve as a long-acting injectable formulation for targeting the adipose tissue region in obese patients.

Effect of tetracycline hydrochloride application on dental pulp stem cell metabolism-booster or obstacle for tissue engineering?

Introduction: Stem cells and scaffolds are an important foundation and starting point for tissue engineering. Human dental pulp stem cells (DPSC) are mesenchymal stem cells with self-renewal and multi-directional differentiation potential, and are ideal candidates for tissue engineering due to their excellent biological properties and accessibility without causing major trauma at the donor site. Tetracycline hydrochloride (TCH), a broad-spectrum antibiotic, has been widely used in recent years for the synthesis of cellular scaffolds to reduce the incidence of postoperative infections. Methods: In order to evaluate the effects of TCH on DPSC, the metabolism of DPSC in different concentrations of TCH environment was tested. Moreover, cell morphology, survival rates, proliferation rates, cell migration rates and differentiation abilities of DPSC at TCH concentrations of 0-500 μg/ml were measured. Phalloidin staining, live-dead staining, MTS assay, cell scratch assay and real-time PCR techniques were used to detect the changes in DPSC under varies TCH concentrations. Results: At TCH concentrations higher than 250 μg/ml, DPSC cells were sequestered, the proportion of dead cells increased, and the cell proliferation capacity and cell migration capacity decreased. The osteogenic and adipogenic differentiation abilities of DPSC, however, were already inhibited at TCH con-centrations higher than 50 μg/ml. Here, the expression of the osteogenic genes, runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN), the lipogenic genes lipase (LPL), as well as the peroxisome proliferator-activated receptor-γ (PPAR-γ) expression were found to be down-regulated. Discussion: The results of the study indicated that TCH in concentrations above 50 µg/ml negatively affects the differentiation capability of DPSC. In addition, TCH at concentrations above 250 µg/ml adversely affects the growth status, percentage of living cells, proliferation and migration ability of cells.

Silver nanoparticle technology in orthopaedic infections

The irrational and prolonged use of antibiotics in orthopaedic infections poses a major threat to the development of antimicrobial resistance. To combat antimicrobial resistance, researchers have implemented various novel and innovative modalities to curb infections. Nanotechnology involves doping ions/metals onto the scaffolds to reach the target site to eradicate the infective foci. In this connotation, we reviewed silver nanoparticle technology in terms of mechanism of action, clinical applications, toxicity, and regulatory guidelines to treat orthopaedic infections.

Antimicrobial and Biodegradable 3D Printed Scaffolds for Orthopedic Infections

In bone tissue engineering, the performance of scaffolds underpins the success of the healing of bone. Microbial infection is the most challenging issue for orthopedists. The application of scaffolds for healing bone defects is prone to microbial infection. To address this challenge, scaffolds with a desirable shape and significant mechanical, physical, and biological characteristics are crucial. 3D printing of antibacterial scaffolds with suitable mechanical strength and excellent biocompatibility is an appealing strategy to surmount issues of microbial infection. The spectacular progress in developing antimicrobial scaffolds, along with beneficial mechanical and biological properties, has sparked further research for possible clinical applications. Herein, the significance of antibacterial scaffolds designed by 3D, 4D, and 5D printing technologies for bone tissue engineering is critically investigated. Materials such as antibiotics, polymers, peptides, graphene, metals/ceramics/glass, and antibacterial coatings are used to impart the antimicrobial features for the 3D scaffolds. Polymeric or metallic biodegradable and antibacterial 3D-printed scaffolds in orthopedics disclose exceptional mechanical and degradation behavior, biocompatibility, osteogenesis, and long-term antibacterial efficiency. The commercialization aspect of antibacterial 3D-printed scaffolds and technical challenges are also discussed briefly. Finally, the discussion on the unmet demands and prevailing challenges for ideal scaffold materials for fighting against bone infections is included along with a highlight of emerging strategies in this field.

3D Printed Materials for Combating Antimicrobial Resistance

Three-dimensional (3D) printing is a rapidly growing technology with a significant capacity for translational applications in both biology and medicine. 3D-printed living and non-living materials are being widely tested as a potential replacement for conventional solutions for testing and combating antimicrobial resistance (AMR). The precise control of cells and their microenvironment, while simulating the complexity and dynamics of an in vivo environment, provides an excellent opportunity to advance the modeling and treatment of challenging infections and other health conditions. 3D-printing models the complicated niches of microbes and host-pathogen interactions, and most importantly, how microbes develop resistance to antibiotics. In addition, 3D-printed materials can be applied to testing and delivering antibiotics. Here, we provide an overview of 3D printed materials and biosystems and their biomedical applications, focusing on ever increasing AMR. Recent applications of 3D printing to alleviate the impact of AMR, including developed bioprinted systems, targeted bacterial infections, and tested antibiotics are presented.

Current Status and Future Outlook of Additive Manufacturing Technologies for the Reconstruction of the Trachea

Tracheal stenosis and defects occur congenitally and in patients who have undergone tracheal intubation and tracheostomy due to long-term intensive care. Such issues may also be observed during tracheal removal during malignant head and neck tumor resection. However, to date, no treatment method has been identified that can simultaneously restore the appearance of the tracheal skeleton while maintaining respiratory function in patients with tracheal defects. Therefore, there is an urgent need to develop a method that can maintain tracheal function while simultaneously reconstructing the skeletal structure of the trachea. Under such circumstances, the advent of additive manufacturing technology that can create customized structures using patient medical image data provides new possibilities for tracheal reconstruction surgery. In this study, the three-dimensional (3D) printing and bioprinting technologies used in tracheal reconstruction are summarized, and various research results related to the reconstruction of mucous membranes, cartilage, blood vessels, and muscle tissue, which are tissues required for tracheal reconstruction, are classified. The prospects for 3D-printed tracheas in clinical studies are also described. This review serves as a guide for the development of artificial tracheas and clinical trials using 3D printing and bioprinting.

Preliminary results of customized bone graft made by robocasting hydroxyapatite and tricalcium phosphates for oral surgery

OBJECTIVE

The objective of this study was to assess the mechanical characteristics and the clinical usefulness of beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) bioblocks grafted in edentulous jaws of 12 patients.

METHODS

The scaffolds were produced by robocasting ceramic inks containing 80%/20% β-TCP and HA, respectively, with an overall porosity of 60%, with a macropore size between 300 and 500 μm. The mechanical performance of cylindrical vs conical specimens was compared using a universal testing machine. The clinical study was performed on 12 edentulous patients who received 4 cylindrical bone bioblocks. After 10 to 16 weeks of osseointegration, the bioblocks were explanted with trephine for histologic analysis by Goldner and Von Kossa staining.

RESULTS

Conical shapes were significantly stronger (96.4 ± 8.7 MPa) than cylindrical shapes (87.8 ± 12.2 MPa). The overall degree of porosity ranged from 53.4% to 58.1% in the coronal region to 62.5% to 66.9% at the apex. After the maturation period, 41 valid bioblocks (85.4%) were obtained for histologic study. Bone showing some cellularity was found in 68.4% of the samples, indicating biologically active bone, and adequate calcification was found in 31.7% of the samples. In terms of biomaterial degradation, 73.2% of the samples were completely resorbed or showed significant resorption.

CONCLUSIONS

The 80%/20% β-TCP and HA grafts customized by robocasting appear adequate for regenerating self-contained defects.

Management of bone diseases: looking at scaffold-based strategies for drug delivery

The bone tissue can regenerate itself completely and continuously; however, large-scale bone defects may overpower this self-regenerative process. Furthermore, the aging population, the increment in obesity incidence, and the sedentary lifestyles are serious risk factors for bone diseases' development which are associated with the self-regenerative process's failure, high morbidity, and mortality rates. Thus, there is an ever-growing need for strategic approaches targeting bone replacement, its remodelling, and its regeneration. Bone scaffolds have successfully been used as synthetic bone grafts for many years, yet recent bone tissue engineering strategies attempt to explore their multifunctionality by investigating them as drug delivery systems. Bone diseases' treatments can be substantially difficult due to the avascular nature of the surrounding cartilage; thus, targeted drug delivery to the bone can be advantageous: it provides local high drug concentrations and minimizes adverse effects while securing a space for new, healthy tissue growth. Despite the promising scientific progress, studies underlining bone scaffolds' use as local drug delivery systems are not abundant. Hence, this work reviews bone scaffolds' therapeutic interest for local drug delivery in five distinct bone disorders-osteomyelitis, osteoporosis, osteoarthritis, osteosarcoma, and cancer bone metastasis. Additionally, it presents the challenges of this possible therapeutic approach and its future perspectives. Albeit bone scaffolds present therapeutic benefits by acting as drug delivery systems, further pre-clinical and clinical assessments are needed to strengthen their understanding and enable research evidence translation into clinical practice. The mismatch between scientific evolution and regulatory frameworks remains one of the major future challenges.

Current research progress of local drug delivery systems based on biodegradable polymers in treating chronic osteomyelitis

Chronic osteomyelitis is one of the most challenging diseases in orthopedic treatment. It is usually treated with intravenous antibiotics and debridement in clinical practice, which also brings systemic drug side effects and bone defects. The local drug delivery system of antibiotics has the characteristics of targeted slow release to the lesion site, replacing systemic antibiotics and reducing the toxic and side effects of drugs. It can also increase the local drug concentration, achieve sound bacteriostatic effects, and promote bone healing and formation. Currently, PMMA beads are used in treating chronic osteomyelitis at home and abroad, but the chain beads need to be removed after a second operation, inconveniences patients. Biodegradable materials have been extensively studied as optimal options for antibiotic encapsulation and delivery, bringing new hope for treating chronic osteomyelitis. This article reviews the research progress of local drug delivery systems based on biodegradable polymers, including natural and synthetic ones, in treating chronic osteomyelitis.

Pharmacokinetic control on the release of antimicrobial drugs from pH-responsive electrospun wound dressings

The acidic pH of healthy skin changes during wound healing due to the exposure of the inner dermal and subcutaneous tissue and due to the potential colonization of pathogenic bacteria. In chronic non-healing wounds, the pH values vary in a wide pH range but the appearance of an alkaline shift is common. After a wound is incurred, neutral pH in the wound bed is characteristic of the activation of the cascade of regenerative and remodeling processes. In order to adjust drug release to the specific pH of the wound, herein, drug-loaded wound dressings having pH-responsiveness containing antiseptics and antibiotics and exerting different release kinetics in order to have a perfect match between the drug release kinetics, and the pH conditions of each wound type, were developed. We have fabricated drug-loaded electrospun nanofibers loaded with the antiseptic chlorhexidine, with the broad-spectrum antibiotic rifampicin, and with the antimicrobial of natural origin thymol, using the pH-dependent methacrylic acid copolymer Eudragit® L100-55, which dissolves at pH > 5.5; those drugs were loaded within Eudragit® S100, which dissolves at pH > 7 and, finally, within the methacrylic ester copolymer Eudragit® RS100 which is pH independent and slowly erodes and releases its contained cargo. The antibacterial action of those advanced wound dressings has been evaluated against methicillin-sensitive S. aureus Newman strain expressing the coral green fluorescent protein (cGFP), as a model of a Gram-positive bacteria, and against E. coli S17 strain as a model of a Gram-negative bacteria. It was demonstrated that those combinational products integrate in one device the required characteristics for a wound dressing with the therapeutic action of a contained active principle and can be selected depending on the wound acidic or alkaline status for its appropriated management.

Three-Dimensional (3D) Printing in Cancer Therapy and Diagnostics: Current Status and Future Perspectives

Three-dimensional (3D) printing is a technique where the products are printed layer-by-layer via a series of cross-sectional slices with the exact deposition of different cell types and biomaterials based on computer-aided design software. Three-dimensional printing can be divided into several approaches, such as extrusion-based printing, laser-induced forward transfer-based printing systems, and so on. Bio-ink is a crucial tool necessary for the fabrication of the 3D construct of living tissue in order to mimic the native tissue/cells using 3D printing technology. The formation of 3D software helps in the development of novel drug delivery systems with drug screening potential, as well as 3D constructs of tumor models. Additionally, several complex structures of inner tissues like stroma and channels of different sizes are printed through 3D printing techniques. Three-dimensional printing technology could also be used to develop therapy training simulators for educational purposes so that learners can practice complex surgical procedures. The fabrication of implantable medical devices using 3D printing technology with less risk of infections is receiving increased attention recently. A Cancer-on-a-chip is a microfluidic device that recreates tumor physiology and allows for a continuous supply of nutrients or therapeutic compounds. In this review, based on the recent literature, we have discussed various printing methods for 3D printing and types of bio-inks, and provided information on how 3D printing plays a crucial role in cancer management.

Additive Manufacturing Strategies for Personalized Drug Delivery Systems and Medical Devices: Fused Filament Fabrication and Semi Solid Extrusion

Novel additive manufacturing (AM) techniques and particularly 3D printing (3DP) have achieved a decade of success in pharmaceutical and biomedical fields. Highly innovative personalized therapeutical solutions may be designed and manufactured through a layer-by-layer approach starting from a digital model realized according to the needs of a specific patient or a patient group. The combination of patient-tailored drug dose, dosage, or diagnostic form (shape and size) and drug release adjustment has the potential to ensure the optimal patient therapy. Among the different 3D printing techniques, extrusion-based technologies, such as fused filament fabrication (FFF) and semi solid extrusion (SSE), are the most investigated for their high versatility, precision, feasibility, and cheapness. This review provides an overview on different 3DP techniques to produce personalized drug delivery systems and medical devices, highlighting, for each method, the critical printing process parameters, the main starting materials, as well as advantages and limitations. Furthermore, the recent developments of fused filament fabrication and semi solid extrusion 3DP are discussed. In this regard, the current state of the art, based on a detailed literature survey of the different 3D products printed via extrusion-based techniques, envisioning future directions in the clinical applications and diffusion of such systems, is summarized.

PCL/Sodium-Alginate Based 3D-Printed Dual Drug Delivery System with Antibacterial Activity for Osteomyelitis Therapy

Chronic osteomyelitis is mostly caused by bacteria such as S. aureus, and is often treated with oral antibiotics or injections to suppress the bacteria. In severe cases, however, surgical treatment using antibiotic beads and metal supports may be required. In these surgeries, bacterial attachment to the metal may lead to biofilm formation and reduce antibiotics’ penetration to the bacteria. Reoperation must be performed to prevent bacterial inflammatory reactions and antibiotic resistance. Thus, in this study, we developed a dual-drug-releasing PCL/sodium-alginate-based 3D-printed scaffold to effectively treat osteomyelitis by removing the biofilm. We proposed an antibiotic-loaded biodegradable polymer scaffold using 3D printing, which was encapsulated by a second antibiotic-containing hydrogel. Then, we successfully established a dual-drug-based scaffold that consisted of a cefazolin (CFZ)-containing polycaprolactone 3D scaffold and a rifampicin (RFP)-loaded alginate hydrogel encapsulating the 3D scaffold. Our scaffold showed a synergistic effect, whereby biofilm formation was inhibited by RFP, which is an external drug, and bacterial activity was inhibited by CFZ, which is an internal drug that increases antibacterial activity. We also confirmed that the dual-drug-based scaffold did not affect the proliferation of human osteoblasts. Our findings suggest that this dual drug delivery system may serve as a new therapeutic treatment for osteomyelitis that overcomes the limitations of individual drugs.

Recent advances in the local antibiotics delivery systems for management of osteomyelitis

Chronic osteomyelitis is a challenging disease due to its serious rates of mortality and morbidity while the currently available treatment strategies are suboptimal. In contrast to the adopted systemic treatment approaches after surgical debridement in chronic osteomyelitis, local drug delivery systems are receiving great attention in the recent decades. Local drug delivery systems using special carriers have the pros of enhancing the feasibility of penetration of antimicrobial agents to bone tissues, providing sustained release and localized concentrations of the antimicrobial agents in the infected area while avoiding the systemic side effects and toxicity. Most important, the incorporation of osteoinductive and osteoconductive materials in these systems assists bones proliferation and differentiation, hence the generation of new bone materials is enhanced. Some of these systems can also provide mechanical support for the long bones during the healing process. Most important, if the local systems are designed to be injectable to the affected site and biodegradable, they will reduce the level of invasion required for implantation and can win the patients’ compliance and reduce the healing period. They will also allow multiple injections during the course of therapy to guard against the side effect of the long-term systemic therapy. The current review presents different available approaches for delivering antimicrobial agents for the treatment of osteomyelitis focusing on the recent advances in researches for local delivery of antibiotics.

HIGHLIGHTS

Chronic osteomyelitis is a challenging disease due to its serious mortality and morbidity rates and limited effective treatment options.

Local drug delivery systems are receiving great attention in the recent decades.

Osteoinductive and osteoconductive materials in the local systems assists bones proliferation and differentiation

Local systems can be designed to provide mechanical support for the long bones during the healing process.

Designing the local system to be injectable to the affected site and biodegradable will reduces the level of invasion and win the patients’ compliance.

Connected healthcare: Improving patient care using digital health technologies

Now more than ever, traditional healthcare models are being overhauled with digital technologies of Healthcare 4.0 increasingly adopted. Worldwide, digital devices are improving every stage of the patient care pathway. For one, sensors are being used to monitor patient metrics 24/7, permitting swift diagnosis and interventions. At the treatment stage, 3D printers are under investigation for the concept of personalised medicine by allowing patients access to on-demand, customisable therapeutics. Robots are also being explored for treatment, by empowering precision surgery, rehabilitation, or targeted drug delivery. Within medical logistics, drones are being leveraged to deliver critical treatments to remote areas, collect samples, and even provide emergency aid. To enable seamless integration within healthcare, the Internet of Things technology is being exploited to form closed-loop systems that remotely communicate with one another. This review outlines the most promising healthcare technologies and devices, their strengths, drawbacks, and opportunities for clinical adoption.

3D Printing of Thermo-Sensitive Drugs

Three-dimensional (3D) printing is among the rapidly evolving technologies with applications in many sectors. The pharmaceutical industry is no exception, and the approval of the first 3D-printed tablet (Spiratam^®) marked a revolution in the field. Several studies reported the fabrication of different dosage forms using a range of 3D printing techniques. Thermosensitive drugs compose a considerable segment of available medications in the market requiring strict temperature control during processing to ensure their efficacy and safety. Heating involved in some of the 3D printing technologies raises concerns regarding the feasibility of the techniques for printing thermolabile drugs. Studies reported that semi-solid extrusion (SSE) is the commonly used printing technique to fabricate thermosensitive drugs. Digital light processing (DLP), binder jetting (BJ), and stereolithography (SLA) can also be used for the fabrication of thermosensitive drugs as they do not involve heating elements. Nonetheless, degradation of some drugs by light source used in the techniques was reported. Interestingly, fused deposition modelling (FDM) coupled with filling techniques offered protection against thermal degradation. Concepts such as selection of low melting point polymers, adjustment of printing parameters, and coupling of more than one printing technique were exploited in printing thermosensitive drugs. This systematic review presents challenges, 3DP procedures, and future directions of 3D printing of thermo-sensitive formulations.

3D-Printing of Drug-Eluting Implants: An Overview of the Current Developments Described in the Literature

The usage of 3D-printing for drug-eluting implants combines the advantages of a targeted local drug therapy over longer periods of time at the precise location of the disease with a manufacturing technique that easily allows modifications of the implant shape to comply with the individual needs of each patient. Research until now has been focused on several aspects of this topic such as 3D-printing with different materials or printing techniques to achieve implants with different shapes, mechanical properties or release profiles. This review is intended to provide an overview of the developments currently described in the literature. The topic is very multifaceted and several of the investigated aspects are not related to just one type of application. Consequently, this overview deals with the topic of 3D-printed drug-eluting implants in the application fields of stents and catheters, gynecological devices, devices for bone treatment and surgical screws, antitumoral devices and surgical meshes, as well as other devices with either simple or complex geometry. Overall, the current findings highlight the great potential of the manufacturing of drug-eluting implants via 3D-printing technology for advanced individualized medicine despite remaining challenges such as the regulatory approval of individualized implants.

Main 3D Manufacturing Techniques for Customized Bone Substitutes. A Systematic Review

Clinicians should be aware of the main methods and materials to face the challenge of bone shortage by manufacturing customized grafts, in order to repair defects. This study aims to carry out a bibliographic review of the existing methods to manufacture customized bone scaffolds through 3D technology and to identify their current situation based on the published papers. A literature search was carried out using "3D scaffold", "bone regeneration", "robocasting" and "3D printing" as descriptors. This search strategy was performed on PubMed (MEDLINE), Scopus and Cochrane Library, but also by hand search in relevant journals and throughout the selected papers. All the papers focusing on techniques for manufacturing customized bone scaffolds were reviewed. The 62 articles identified described 14 techniques (4 subtraction + 10 addition techniques). Scaffold fabrication techniques can be also be classified according to the time at which they are developed, into Conventional techniques and Solid Freeform Fabrication techniques. The conventional techniques are unable to control the architecture of the pore and the pore interconnection. However, current Solid Freeform Fabrication techniques allow individualizing and generating complex geometries of porosity. To conclude, currently SLA (Stereolithography), Robocasting and FDM (Fused deposition modeling) are promising options in customized bone regeneration.

Antibacterial biomaterials in bone tissue engineering

Bone infection is a devastating disease characterized by recurrence, drug-resistance, and high morbidity, that has prompted clinicians and scientists to develop novel approaches to combat it. Currently, although numerous biomaterials that possess excellent biocompatibility, biodegradability, porosity, and mechanical strength have been developed, their lack of effective antibacterial ability substantially limits bone-defect treatment efficacy. There is, accordingly, a pressing need to design antibacterial biomaterials for effective bone-infection prevention and treatment. This review focuses on antibacterial biomaterials and strategies; it presents recently reported biomaterials, including antibacterial implants, antibacterial scaffolds, antibacterial hydrogels, and antibacterial bone cement types, and aims to provide an overview of these antibacterial materials for application in biomedicine. The antibacterial mechanisms of these materials are discussed as well.

An injectable and antibacterial calcium phosphate scaffold inhibiting Staphylococcus aureus and supporting stem cells for bone regeneration

Staphylococcus aureus (S. aureus) is the major pathogen for osteomyelitis, which can lead to bone necrosis and destruction. There has been no report on antibacterial calcium phosphate cement (CPC) against S. aureus. The aims of this study were to: (1) develop novel antibacterial CPC-chitosan-alginate microbead scaffold; (2) investigate mechanical and antibacterial properties of CPC-chitosan-penicillin-alginate scaffold; (3) evaluate the encapsulation and delivery of human umbilical cord mesenchymal stem cells (hUCMSCs). Flexural strength, elastic modulus and work-of-fracture of the CPC-chitosan-penicillin-alginate microbeads scaffold and CPC-chitosan scaffold were evaluated. Penicillin release profile and antibacterial effects on S. aureus were determined. The hUCMSC delivery and release from penicillin-alginate microbeads were investigated. Injectable CPC-chitosan-penicillin-alginate microbeads scaffold was developed for the first time. CPC-chitosan-penicillin-alginate microbeads scaffold had a flexural strength of 3.16 ± 0.55 MPa, matching that of cancellous bone. With sustained penicillin release, the new scaffold had strong antibacterial effects on S. aureus, with an inhibition zone diameter of 32.2 ± 2.5 mm, greater than that of penicillin disk control (15.1 ± 2.0 mm) (p < 0.05). Furthermore, this injectable and antibacterial scaffold had no toxic effects, yielding excellent hUCMSC viability, which was similar to that of CPC control without antibacterial activity (p > 0.05). CPC-chitosan-penicillin-microbeads scaffold had injectability, good strength, strong antibacterial effects, and good biocompatibility to support stem cell viability for osteogenesis. CPC-chitosan-penicillin-microbeads scaffold is promising for dental, craniofacial and orthopedic applications to combat infections and promote bone regeneration.

Chitosan-based drug delivery systems: From synthesis strategy to osteomyelitis treatment - A review

Osteomyelitis is a complex disease in orthopedics mainly caused by bacterial pathogens invading bone or bone marrow. The treatment of osteomyelitis is highly difficult and it is a major challenge in orthopedic surgery. The long-term systemic use of antibiotics may lead to antibiotic resistance and has limited effects on eradicating local biofilms. Localized antibiotic delivery after surgical debridement can overcome the problem of antibiotic resistance and reduce systemic toxicity. Chitosan, a special cationic polysaccharide, is a product extracted from the deacetylation of chitin. It has numerous advantages, such as nontoxicity, biocompatibility, and biodegradability. Recently, chitosan has attracted significant attention in bacterial inhibition and drug delivery. Because chitosan contains many functional bioactive groups conducive to chemical reaction and modification, some chitosan-based biomaterials have been applied as the local antibiotic delivery systems in the treatment of osteomyelitis. This review aims to introduce recent advances in the biomedical applications of chitosan-based drug delivery systems in osteomyelitis treatment and to highlight the perspectives for further studies.