Lovastatin release from polycaprolactone coated β-tricalcium phosphate: effects of pH, concentration and drug-polymer interactions

Natural medicine delivery from 3D printed bone substitutes

Unmet medical needs in treating critical-size bone defects have led to the development of numerous innovative bone tissue engineering implants. Although additive manufacturing allows flexible patient-specific treatments by modifying topological properties with various materials, the development of ideal bone implants that aid new tissue regeneration and reduce post-implantation bone disorders has been limited. Natural biomolecules are gaining the attention of the health industry due to their excellent safety profiles, providing equivalent or superior performances when compared to more expensive growth factors and synthetic drugs. Supplementing additive manufacturing with natural biomolecules enables the design of novel multifunctional bone implants that provide controlled biochemical delivery for bone tissue engineering applications. Controlled release of naturally derived biomolecules from a three-dimensional (3D) printed implant may improve implant-host tissue integration, new bone formation, bone healing, and blood vessel growth. The present review introduces us to the current progress and limitations of 3D printed bone implants with drug delivery capabilities, followed by an in-depth discussion on cutting-edge technologies for incorporating natural medicinal compounds embedded within the 3D printed scaffolds or on implant surfaces, highlighting their applications in several pre- and post-implantation bone-related disorders.

Bisphosphonate-incorporated coatings for orthopedic implants functionalization

Bisphosphonates (BPs), the stable analogs of pyrophosphate, are well-known inhibitors of osteoclastogenesis to prevent osteoporotic bone loss and improve implant osseointegration in patients suffering from osteoporosis. Compared to systemic administration, BPs-incorporated coatings enable the direct delivery of BPs to the local area, which will precisely enhance osseointegration and bone repair without the systemic side effects. However, an elaborate and comprehensive review of BP coatings of implants is lacking. Herein, the cellular level (e.g., osteoclasts, osteocytes, osteoblasts, osteoclast precursors, and bone mesenchymal stem cells) and molecular biological regulatory mechanism of BPs in regulating bone homeostasis are overviewed systematically. Moreover, the currently available methods (e.g., chemical reaction, porous carriers, and organic material films) of BP coatings construction are outlined and summarized in detail. As one of the key directions, the latest advances of BP-coated implants to enhance bone repair and osseointegration in basic experiments and clinical trials are presented and critically evaluated. Finally, the challenges and prospects of BP coatings are also purposed, and it will open a new chapter in clinical translation for BP-coated implants.

Mevacor/Poly(vinyl acetate/2-hydroxyethyl methacrylate) as Solid Solution: Preparation, Solubility Enhancement and Drug Delivery

Mevacor/Poly(vinyl acetate-co-2-hydroxyethyl methacrylate) drug carrier systems (MVR/VAC-HEMA) containing different Mevacor (MVR) contents were prepared in one pot by free radical copolymerization of vinyl acetate with 2-hydroxyethyl methacrylate using an LED lamp light in the presence of camphorquinone as a photoinitiator and Mevacor as a drug filler. The prepared material was characterized by FTIR, 1H NMR, DSC, SEM and XRD methods. Different parameters influencing the efficiency in the Mecvacor-water solubility and the drug delivery of this system, such as the swelling capacity of the carrier, the amount of Mevacor loaded and the pH medium have been widely investigated. The results obtained revealed that the Mevacor particles were uniformly dispersed in their molecular state in the copolymer matrix forming a solid solution; the cell toxicity of the virgin poly(vinyl acetate-co-2-hydroxy ethyl methacrylate) (VAC-HEMA) and MVR/VAC-HEMA drug carrier system exhibited no significant effect on their viability when between 0.25 and 2.00 wt% was loaded in these materials; the average swelling capacity of VAC-HEMA material in water was found to be 45.16 wt%, which was practically unaffected by the pH medium and the solubility of MVR deduced from the release process reached more than 22 and 37 times that of the powder dissolved directly in pH 1 and 7 media, respectively. The in vitro MVR release kinetic study revealed that the MVR/VAC-HEMA system containing 0.5 wt% MVR exhibited the best performance in the short gastrointestinal transit (GITT), while that containing 2.0 wt% is for the long transit as they were able to considerably reduce the minimum release of this drug in the stomach (pH1).

Functionalization of biomimetic mineralized collagen for bone tissue engineering

Mineralized collagen (MC) is the basic unit of bone structure and function and is the main component of the extracellular matrix (ECM) in bone tissue. In the biomimetic method, MC with different nanostructures of neo-bone have been constructed. Among these, extra-fibrous MC has been approved by regulatory agencies and applied in clinical practice to play an active role in bone defect repair. However, in the complex microenvironment of bone defects, such as in blood supply disorders and infections, MC is unable to effectively perform its pro-osteogenic activities and needs to be functionalized to include osteogenesis and the enhancement of angiogenesis, anti-infection, and immunomodulation. This article aimed to discuss the preparation and biological performance of MC with different nanostructures in detail, and summarize its functionalization strategy. Then we describe the recent advances in the osteo-inductive properties and multifunctional coordination of MC. Finally, the latest research progress of functionalized biomimetic MC, along with the development challenges and future trends, are discussed. This paper provides a theoretical basis and advanced design philosophy for bone tissue engineering in different bone microenvironments.

Phytosterol-Loaded Surface-Tailored Bioactive-Polymer Nanoparticles for Cancer Treatment: Optimization, In Vitro Cell Viability, Antioxidant Activity, and Stability Studies

This study aimsto optimize, characterize, and assess the phytosterol-loaded surface-tailored bioactive Alginate/Chitosan NPs for antitumor efficacy against breast cancer. β-Sitosterol-loaded Alginate/Chitosan nanoparticles (β-SIT-Alg/Ch-NPs) were fabricated using an ion-gelation technique, and then the NPs’ surfaces were activated using an EDC/sulfo-NHS conjugation reaction. The activated chitosan NPs werefunctionalized with folic acid (FA), leveled as β-SIT-Alg/Ch-NPs-FA. Moreover, the functionalized NPs were characterized for size distribution, polydispersity index (PDI), and surface charge, FT-IR and DSC. β-SIT released from β-SIT-Alg/Ch-NPs was estimated in various biorelevant media of pH 7.4, 6.5, and 5.5, and data werefitted into various kinetic models. The cytotoxic study of β-SIT-Alg/Ch-NPs-FA against the cancer cell line was established. The antioxidant study of developed β-SIT-Alg/Ch-NPs was performed using DPPH assay. The stability of developed optimized formulation was assessed in phosphate buffer saline (PBS, pH 7.4), as per ICH guidelines. The drug-entrapped Alg/Ch-NPs-FA appeared uniform and nonaggregated, and the nanoscale particle measured a mean size of 126 ± 8.70 nm. The %drug encapsulation efficiency and %drug loading in β-SIT-Alg/Ch-NPs-FA were 91.06 ± 2.6% and 6.0 ± 0.52%, respectively. The surface charge on β-SIT-Alg/Ch-NPs-FA was measured as +25 mV. The maximum β-SIT release from β-SIT-Alg/Ch-NPs-FA was 71.50 ± 6.5% in pH 5.5. The cytotoxic assay expressed an extremely significant antitumor effect by β-SIT-Alg/Ch-NPs-FA when compared to β-SIT-suspension (p < 0.001). The antioxidant capacity of β-SIT-Alg/Ch-NPs-FA was 91 ± 5.99% compared to 29 ± 8.02% for β-SIT-suspension. The stability of NPs noticed an unworthy alteration (p > 0.05) in particle sizes and other parameters under study in the specific period.

Curcumin polymeric membranes for postoperative peritoneal adhesion: Comparison of nanofiber vs. film and phospholipid-enriched vs. non-enriched formulations

Intra-abdominal adhesion remains a major postoperative problem and is able to place individuals at lifelong risk of serious complications. Among available approaches, insertion of a barrier membrane at the site of injury partially inhibited adhesion formation. Moreover, the local administration of an anti-adhesive agent showed some favorable effects. In this study, we aimed to prepare and fully characterize polycaprolactone (PCL)-based film casts and electrospun nanofibers (NFs) containing a natural anti-inflammatory agent, curcumin (CUR), with extended-release properties. We also compared their efficiencies in preventing tissue adhesions. Additionally, the impact of soy phosphatidylcholine (SPC) enrichment on adhesion prevention was investigated. Prepared membranes were evaluated in terms of surface morphology (SEM, AFM), surface wettability, CUR release profiles, structural properties (FTIR, XRD, DSC), and mechanical behaviors. To further analyze the anti-adhesion effectiveness, a cecal abrasion model was performed on rats. SEM and AFM images showed a smoother surface in SPC-containing films. Concerning NFs, uniform bead-free fibers were observed and SPC containing NFs showed higher conductivity and lower viscosity and therefore, smaller fibers. All formulations exhibited sustained drug release over 4 weeks. In vivo findings revealed the superior performance of films compared to NFs and phospholipid-enriched formulations over non-enriched ones. Among all film formulations and in comparison to the positive control (Seprafilm®), CUR-SPC-PCL films significantly reduced peritoneal adhesions, as evidenced by gross examination, histological evaluation and immunohistochemical (IHC) analysis. The remarkable in vivo anti-adhesion activity together with suitable in vitro properties have made CUR-SPC-PCL films a promising system for postoperative anti-adhesion purposes in the clinic.

Simvastatin-Incorporated Drug Delivery Systems for Bone Regeneration

Local drug delivery systems composed of biomaterials and osteogenic substances provide promising strategies for the reconstruction of large bone defects. In recent years, simvastatin has been studied extensively for its pleiotropic effects other than lowering of cholesterol, including its ability to induce osteogenesis and angiogenesis. Accordingly, several studies of simvastatin incorporated drug delivery systems have been performed to demonstrate the feasibility of such systems in enhancing bone regeneration. Therefore, this review explores the molecular mechanisms by which simvastatin affects bone metabolism and angiogenesis. The simvastatin concentrations that promote osteogenic differentiation are analyzed. Furthermore, we summarize and discuss a variety of simvastatin-loaded drug delivery systems that use different loading methods and materials. Finally, current shortcomings of and future development directions for simvastatin-loaded drug delivery systems are summarized. This review provides various advanced design strategies for simvastatin-incorporated drug delivery systems that can enhance bone regeneration.

Cytotoxic and osteogenic effects of crocin and bicarbonate from calcium phosphates for potential chemopreventative and anti-inflammatory applications in vitro and in vivo

Delayed healing and nonhealing of bone defects or resected bone sites remains an important clinical concern in the biomedical field. Osteosarcoma is one of the most common types of primary bone cancers. Among calcium phosphates, hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most widely used in various biomedical applications for bone reconstruction and replacement. In this study, crocin, saffron's natural bioactive and anti-inflammatory molecule, and bicarbonate, a neutralizing agent, were directly loaded onto HA disks to evaluate their in vitro release and effect on human osteoblast and osteosarcoma cell lines. This was assessed through release, initial toxicity, drug optimization, final toxicity studies and in vivo anti-inflammatory assessment through H&E indexing. It is hypothesized that the release of crocin, bicarbonate, and the dual release of both agents will decrease osteosarcoma cellular viability with no effect on osteoblast cells. A plateaued release of crocin and bicarbonate was achieved over seven weeks in physiological and acidic environments, where bicarbonate was shown to modulate the release of crocin. Through morphological characterization and MTT assay analysis, bicarbonate showed no toxicity to human fetal osteoblast (hFOB) cells and crocin significantly enhanced osteoblast proliferation. Through drug concentration optimization, all drug loaded samples decreased human osteosarcoma (MG-63) viability by 50% compared to control samples by Day 11, with clear changes in cell spreading and morphology. Moreover, 3D printed TCP scaffolds loaded with crocin and bicarbonate were tested in vivo in order to assess their preliminary effects on inflammation in a rat distal femur model at 4 days. Lower inflammatory cellular recruitment was achieved in the presence of crocin and bicarbonate, compared to the control. These results suggest a pro-apoptotic mechanism against osteosarcoma as well as anti-inflammatory properties of crocin and bicarbonate, elucidating a potential application for osteosarcoma regulation and wound healing for bone tissue regeneration applications.

Crystallization of carboplatin-loaded onto microporous calcium phosphate using high-vacuum method: Characterization and release study

Drug delivery systems are a new approach to increase therapeutic efficacy and to reduce the side effects of traditional treatments. Calcium phosphates (CaPs) have been studied as drug delivery systems, especially in bone diseases. However, each system has some particularities that depend on the physical and chemical characteristics of the biomaterials and drug interaction. In this work, granulated CaPs were used as a matrix for loading the anticancer drug carboplatin using the high-vacuum method. Five compositions were applied: hydroxyapatite (HA), β-tricalcium phosphate (β-TCP), biphasic HAp 60%/β-TCP 40% (BCP), β-TCP/MgO nanocomposite, and β-TCP/SiO2 nanocomposite. Carboplatin drug in 50, 60, and 70 mg/g was precipitated on the surface of CaPs. Morphological, chemical and surface modifications in the carboplatin-CaPs were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), backscattered electron microscopy (BSE), X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared (FT-IR), and Raman spectroscopy. The characterization of the CaP-carboplatin biomaterials showed heterogeneous crystalline precipitation of the drug, and no morphological modifications of the CaPs biomaterials. The in vitro release profile of carboplatin from CaPs was evaluated by the ultraviolet-visible (UV-Vis) method. The curves showed a burst release of upon 60% of carboplatin loaded followed by a slow-release of the drug for the time of the study. The results were typical of a low-interaction system and physisorption mechanism. The high-vacuum method permitted to load the high amount of carboplatin drug on the surface of the biomaterials despite the low interaction between carboplatin and CaPs.

3D PCL/fish collagen composite scaffolds incorporating osteogenic abalone protein hydrolysates for bone regeneration application: in vitro and in vivo studies

Three-dimensional (3 D) printing is an effective technology that has shown considerable potential for use in tissue regeneration. Of the many materials that have been proposed for this purpose, poly (ε-caprolactone) (PCL) 3 D scaffolds have been received significant attention in the bone tissue engineering field due to its advantageous mechanical properties and biocompatibility. In this study, a novel method was developed for tissue-engineered bone that combines PCL 3 D scaffolds with fish collagen (Col) and the osteogenic abalone intestine gastro-intestinal digests (AIGIDs) from Haliotis discus hannai. And then, mouse mesenchymal stem cells (MSCs) were seeded onto the fabricated scaffolds. After in vitro culturing, the proliferation of the MSCs on the scaffolds, alkaline phosphatase (ALP) activity, and the amount of deposited calcium were investigated. The results indicated that the ALP activity and mineralization in PCL/AIGIDs/Col was higher than that of the other scaffolds. In an in vivo experiment, the two fabricated scaffolds were implanted in a rabbit tibia. PCL/AIGIDs/Col group exhibited strong osteoinduction capability in the rabbit tibia defect model. These stimulated biological responses in vitro and in vivo suggest that the PCL/AIGIDs/Col scaffold are promising material for use in tissue implants and bone regeneration.

β-tricalcium phosphate for bone substitution: Synthesis and properties

β-tricalcium phosphate (β-TCP) is one the most used and potent synthetic bone graft substitute. It is not only osteoconductive, but also osteoinductive. These properties, combined with its cell-mediated resorption, allow full bone defects regeneration. Its clinical outcome is sometimes considered to be "unpredictable", possibly due to a poor understanding of β-TCP physico-chemical properties: β-TCP crystallographic structure is not fully uncovered; recent results suggest that sintered β-TCP is coated with a Ca-rich alkaline phase; β-TCP apatite-forming ability and osteoinductivity may be enhanced by a hydrothermal treatment; β-TCP grain size and porosity are strongly modified by the presence of minute amounts of β-calcium pyrophosphate or hydroxyapatite impurities. The aim of the present article is to provide a critical, but still rather comprehensive review of the current state of knowledge on β-TCP, with a strong focus on its synthesis and physico-chemical properties, and their link to the in vivo response. STATEMENT OF SIGNIFICANCE: The present review documents the richness, breadth, and interest of the research devoted to β-tricalcium phosphate (β-TCP). β-TCP is synthetic, osteoconductive, osteoinductive, and its resorption is cell-mediated, thus making it one of the most potent bone graft substitutes. This comprehensive review reveals that there are a number of aspects, such as surface chemistry, crystallography, or stoichiometry deviations, that are still poorly understood. As such, β-TCP is still an exciting scientific playground despite a 50 year long history and > 200 yearly publications.

Effects of chitosan-loaded hydroxyapatite on osteoblasts and osteosarcoma for chemopreventative applications

Osteosarcoma remains one of the most common malignant primary bone tumors. Post-surgical defect repair combined with tumor suppression remains a major clinical challenge. Investigations of alternative treatments for osteosarcoma, while promising, have led to multi-drug resistance. These constraints of common treatment strategies have triggered the need for new therapeutic candidates in bone cancer treatment. Chitosan, a common biopolymer utilized in bone and tissue engineering applications, has recently been studied as a pro-apoptotic agent in metastatic cell lines like breast cancer, but has not been utilized in bone cancer applications. In this study, chitosan was directly loaded onto HA disks to evaluate its in vitro release and effects on human fetal osteoblast (hFOB) and human osteosarcoma (MG-63) cell lines. It is hypothesized that the sustained release of chitosan will decrease osteosarcoma cell proliferation and enhance proliferation of osteoblast cells. Through morphological characterization and MTT assay analysis, chitosan showed no toxicity to human fetal osteoblast (hFOB) cells. Chitosan was also shown to decrease human osteosarcoma cell viability by up to 96% compared to control samples. This suggests a pro-apoptotic mechanism against osteosarcoma as well as the potential clinical application of chitosan as a drug candidate in ceramic scaffolds at tumor resected sites.

Natural Medicinal Compounds in Bone Tissue Engineering

Recent advances in 3D printing have provided unprecedented opportunities in bone tissue engineering applications for producing a variety of complex patient-specific implants for the treatment of critical-sized bone defects. Natural medicinal compounds (NMCs) with osteogenic potential can be incorporated into these 3D-printed parts to improve bone formation and therefore enhance implant performance. Using NMCs to treat bone-related disorders may prove to be a healthy preventive choice as they are considered safe, have lesser or no side effects, and are more suitable for prolonged use than synthetic drugs. In this review paper, the current challenges of bone tissue engineering are addressed briefly, highlighting the immense potential of NMCs integrated within tissue engineering scaffolds for orthopedic and dental applications.

Characterization of chitosan/alginate/lovastatin nanoparticles and investigation of their toxic effects in vitro and in vivo

In this study, chitosan and alginate were selected to prepare alginate/chitosan nanoparticles to load the drug lovastatin by the ionic gelation method. The synthesized nanoparticles loaded with drug were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), laser scattering and differential scanning calorimetry (DSC) methods. The FTIR spectrum of the alginate/chitosan/lovastatin nanoparticles showed that chitosan and alginate interacted with lovastatin through hydrogen bonding and dipolar-dipolar interactions between the C-O, C=O, and OH groups in lovastatin, the C-O, NH, and OH groups in chitosan and the C-O, C=O, and OH groups in alginate. The laser scattering results and SEM images indicated that the alginate/chitosan/lovastatin nanoparticles have a spherical shape with a particle size in the range of 50-80 nm. The DSC diagrams displayed that the melting temperature of the alginate/chitosan/lovastatin nanoparticles was higher than that of chitosan and lower than that of alginate. This result means that the alginate and chitosan interact together, so that the nanoparticles have a larger crystal degree when compared with alginate and chitosan individually. Investigations of the in vitro lovastatin release from the alginate/chitosan/lovastatin nanoparticles under different conditions, including different alginate/chitosan ratios, different solution pH values and different lovastatin contents, were carried out by ultraviolet-visible spectroscopy. The rate of drug release from the nanoparticles is proportional to the increase in the solution pH and inversely proportional to the content of the loaded lovastatin. The drug release process is divided into two stages: a rapid stage over the first 10 hr, then the release becomes gradual and stable. The Korsmeyer-Peppas model is most suitable for the lovastatin release process from the alginate/chitosan/lovastatin nanoparticles in the first stage, and then the drug release complies with other models depending on solution pH in the slow release stage. In addition, the toxicity of alginate/chitosan/lovastatin (abbreviated ACL) nanoparticles was sufficiently low in mice in the acute toxicity test. The LD₅₀ of the drug was higher than 5000 mg/kg, while in the subchronic toxicity test with treatments of 100 mg/kg and 300 mg/kg ACL nanoparticles, there were no abnormal signs, mortality, or toxicity in general to the function or structure of the crucial organs. The results show that the ACL nanoparticles are safe in mice and that these composite nanoparticles might be useful as a new drug carrier.

Bisphosphonate-Functionalized Scaffolds for Enhanced Bone Regeneration

The local sustained release of bioactive substances are attracting increasing attention in bone tissue engineering, which is beneficial to bone tissue formation and helps to improve the bone ingrowth ability of a scaffold. Bisphosphonates (BPs), as a representative kind of osteoclast inhibitors, are proven to possess excellent osteogenic induction capability. Accordingly, various physical and chemical strategies are developed to functionalize bone tissue scaffolds with BPs to achieve controlled release profiles. Compared with traditional treatment modalities, local release of BPs from these composite scaffolds will contribute to continuous bone integration without the risk of many complications. This review explores the molecular mechanisms of BPs on bone metabolism and analyzes the appropriate concentrations of BPs that promote bone regeneration. The advanced BP loading strategies, implant modification technologies, and BP-loaded composite scaffolds based on different matrices are summarized. Finally, the latest advances and the future development of BP-modified scaffolds for enhanced bone regeneration are discussed. This article provides leading-edge design strategies of the BP-functionalized bone engineering scaffolds for improved bone repairability.

Kinetic Study of Controlled Asphaltene Inhibitor Release from Nanoemulsions

Asphaltene aggregation and subsequent precipitation in the nonpolar medium may have a profound effect on plugging wellbores and production equipment. Continuing our work on controlled release of asphaltene inhibitor (AI) by using nanoemulsions (NEs), this work provides new evidence about long-term asphaltene stability by using optical measurement and reveals the kinetic processes of inhibitor transport/release mechanisms. Multiple light scattering (Turbiscan) and dynamic light scattering have been used to study "in situ" the effectiveness and performance of the proposed controlled release in three cases of asphaltene aggregation/precipitation in the presence of: (i) strong organic acids (dodecyl benzene sulfonic acid, DBSA), (ii) NEs (blank NEs), and (iii) NEs loaded with DBSA (DBSA NEs). The results suggested that the new approach reduced the amount of AI by ∼20 times and achieved high asphaltene inhibition efficiency of ∼84% with a prolonged release time. A mechanistic understanding of the controlled release effect was proposed based on the effect of DBSA NEs on the asphaltene particle morphology variation, which was related to the hydrophilicity of DBSA and the strong intermolecular interactions among all DBSA NE components. The release mechanism of the AI from the NE was evaluated using eight release models and was found to follow the Korsmeyer-Peppas kinetic model.

Sustained release of vitamin C from PCL coated TCP induces proliferation and differentiation of osteoblast cells and suppresses osteosarcoma cell growth

The objective of this study is to understand the effect of sustained release of vitamin C from β-tricalcium phosphate (β-TCP) scaffold on proliferation, viability and differentiation of human fetal osteoblast cells (hFOB). The influence of pH, drug concentration, and presence of polymer on the sustained release of vitamin C from polycaprolactone (PCL) coated β-TCP scaffolds are studied. Prolonged and sustained release of vitamin C, over 60 days is observed in PCL coated β-TCP scaffolds compared to uncoated scaffolds. Presence of PCL helps to minimize the burst release of vitamin C from β-TCP scaffolds in the initial 24 h of release. To evaluate the osteogenic potential of vitamin C incorporated β-TCP scaffolds, osteoblast cells are cultured and cell morphology, proliferation, viability, and differentiation are assessed. Morphological characterization shows layer like osteoblast cell attachment in the presence of vitamin C compared to the control. MTT cell viability assay shows 2 folds increase in osteoblast cell density in the presence of vitamin C after 3,7 and 11 days of culture. Furthermore, increased ALP activity at 11 days of culture indicates the possible role of vitamin C on osteoblast differentiation. Additionally, a preliminary study shows vitamin C loaded scaffolds suppress osteosarcoma (MG-63) cell proliferation to 4 folds after 3 days compared to control. These results show a sustained release of vitamin C from PCL coated β-TCP scaffolds improve proliferation, viability, and differentiation of osteoblasts cell as well as mitigate osteosarcoma cell proliferation, suggesting its potential application as synthetic bone graft substitutes in tissue engineering application.

Clinical significance of three-dimensional printed biomaterials and biomedical devices

Three-dimensional printing (3DP) is becoming a standard manufacturing practice for a variety of biomaterials and biomedical devices. This layer-by-layer methodology provides the ability to fabricate parts from computer-aided design files without the need for part-specific tooling. Three-dimensional printed medical components have transformed the field of medicine through on-demand patient care with specialized treatment such as local, strategically timed drug delivery, and replacement of once-functioning body parts. Not only can 3DP technology provide individualized components, it also allows for advanced medical care, including surgical planning models to aid in training and provide temporary guides during surgical procedures for reinforced clinical success. Despite the advancement in 3DP technology, many challenges remain for forward progress, including sterilization concerns, reliability, and reproducibility. This article offers an overview of biomaterials and biomedical devices derived from metals, ceramics, polymers, and composites that can be three-dimensionally printed, as well as other techniques related to 3DP in medicine, including surgical planning, bioprinting, and drug delivery.

Comparative effects of controlled release of sodium bicarbonate and doxorubicin on osteoblast and osteosarcoma cell viability

This study intends to analyze the effects of doxorubicin and sodium bicarbonate release with polycaprolactone (PCL) coating on calcium phosphate system which is a bone like material, on the cell viability and proliferation of osteosarcoma and osteoblast. Increased systematic pH concentrations locally by the release of sodium bicarbonate diminished acidosis and hence, alleviated malignancy. In our studies, we have shown that the same of dosage of doxorubicin inhibited both osteoblast and osteosarcoma cell attachment and viability whereas, sodium bicarbonate abated osteosarcoma cell proliferation. Sodium bicarbonate also inhibited osteoblast cell proliferation in the early time points, however, the cell viability increased after the initial burst release of the molecule. Polymer coating on calcium phosphate-based implants, as carriers of drug, can minimize chances of toxic effects of higher oral drug dosage in the body, and also help in delivering effective doses of drugs, locally to the target tissues, as compared to the oral drug delivery approach. A coating of PCL was thus incorporated to control the initial burst release of bicarbonate, which enhanced the osteoblast cell viability, but was capable of diminishing osteosarcoma cell proliferation. The novelty and clinical significance of this study lies in the understanding of unique delivery using encapsulated naturally occurring and more benign sodium bicarbonate, for usage after excision of the cancerous bone, without any adverse effects on normal bone cells.

Effects of vitamin D3 release from 3D printed calcium phosphate scaffolds on osteoblast and osteoclast cell proliferation for bone tissue engineering

Vitamin D₃ is a hydrophobic micronutrient and is known for inhibiting osteoclastic bone resorption in vivo via suppression of the Receptor Activator of Nuclear factor-Kappa B (RANK ligand) expression in osteoblasts. Although vitamin D is well-known for its promotion in bone health, little is known on its effects directly on bone cells. The objective of this study was to understand the effects of vitamin D₃ release from 3D printed calcium phosphate scaffolds towards bone cell proliferation. In this study, cholecalciferol, a common intake form of vitamin D₃, was successfully able to release from the scaffold matrix via the use of polyethylene glycol. Results showed a decrease in osteoclast resorption pits and healthier osteoblast cellular morphology compared to the control. Additively manufactured tricalcium phosphate scaffolds with designed porosity were loaded with vitamin D₃ and showed controlled release profiles in phosphate buffer and acetate buffer solutions. The release kinetics of vitamin D₃ from calcium phosphate scaffolds enabling osteoblast proliferation and inhibiting osteoclastic resorption can enhance healing for low load bearing applications for bone defects or permeate voids left by tumor resection.

Release of Vitamin D₃, cholecalciferol, from 3D printed calcium phosphate scaffolds showed reduced osteoclast resorption activity.

Gelatin-Coated Polycaprolactone Nanoparticle-Mediated Naringenin Delivery Rescue Human Mesenchymal Stem Cells from Oxygen Glucose Deprivation-Induced Inflammatory Stress

Ischemic stroke involves pro-inflammatory species, which implicates inflammation in the disease mechanism. Recent studies indicate that the prevalence of therapeutic choice such as stem cell transplantation has seen an upsurge in ischemic stroke. However, after transplantation the fate of transplanted cells is largely unknown. Human mesenchymal stem cells (MSCs), due to their robust survival rate upon transplantation in brain tissue, are being widely employed to treat ischemic stroke. In the present study, we have evaluated naringenin-loaded gelatin-coated polycaprolactone nanoparticles (nar-gel-c-PCL NPs) to rescue MSCs against oxygen glucose deprived insult. Naringenin, due to its strong anti-inflammatory effects, remains a therapeutic choice in neurological disorders. Though, the low solubility and inefficient delivery remain challenges in using naringenin as a therapeutic drug. The present study showed that inflammation occurred in MSCs during their treatment with oxygen glucose deprivation (OGD) and was well overturned by treatment with nar-gel-c-PCL NPs. In brief, the results indicated that nar-gel-c-PCL NPs were able to protect the loss of cell membrane integrity and restored neuronal morphology. Then nar-gel-c-PCL NPs successfully protected the human MSCs against OGD-induced inflammation as evident by reduced level of pro-inflammatory cytokine (TNF-α, IFN-γ, and IL-1β) and other inflammatory biomarkers (COX2, iNOS, and MPO activity). Therefore, the modulation of inflammation by treatment with nar-gel-c-PCL NPs in MSCs could provide a novel strategy to improve MSC-based therapy, and thus, our nanoformulation may find a wide therapeutic application in ischemic stroke and other neuro-inflammatory diseases.

Alendronate delivery on amino modified mesoporous bioactive glass scaffolds to enhance bone regeneration in osteoporosis rats

The regeneration capacity of osteoporotic bones is generally lower than that of normal bones. Nowadays, alendronate (AL) are orally administrated for osteoporosis due to the inhibition of bone resorption. However, systemic administration of AL is characterized by extremely low bioavailability and high toxicity. In this study, the amino-modified mesoporous bioactive glass scaffolds (N-MBGS) were fabricated by a simple powder processing technique as a novel drug-delivery system for AL. The effects of AL on the osteogenic differentiation of bone mesenchymal stem cells derived from ovariectomized rats (rBMSCs-OVX) were first estimated. The loading efficiency and release kinetics of AL on N-MBGS were investigated in vitro and the osteogenesis of AL-loaded N-MBGS in rat calvarial defect model was detected by micro-CT measurements and the histological assay. Our results revealed that proper concentration of AL significantly promoted osteogenic differentiation of rBMSCs-OVX. The amount and delivery rate of AL were greatly improved through amino modification. Additionally, scaffolds with AL showed better bone formation in vivo, especially for the N-MBGS group. Our results suggest that the novel amino-modified MBGS are promising drug-delivery system for osteoporotic bone defect repairing or regeneration. The experimental schematic of the novel amino-modified MBGS as a promising drug-delivery system for osteoporotic bone regeneration.

Design of a cytocompatible hydrogel coating to modulate properties of ceramic-based scaffolds for bone repair

Introduction

Physical and mechanical properties of ceramic-based scaffolds can be modulated by introducing hydrogel coatings on their surface. For instance, hydrogels can be used as elastic layers to overcome the brittleness of synthetic ceramic materials or to control the delivery of essential osteogenic factors. In this work, we aimed to achieve both goals by fabricating a novel cytocompatible hydrogel made of gelatin-alginate as a coating for beta-tricalcium phosphate (β-TCP) scaffolds.

Methods

The hydrogel synthesis was optimized by varying the concentration of the crosslinkers N-hydroxysuccinimide and N-Ethyl-N'-(3-dimethyl aminopropyl) carbodiimide (NHS/EDC). Swelling, degradability and mechanical studies were carried out to identify the suitable hydrogel coating formulation for the β-TCP scaffolds. The cytocompatibility of the coated ceramic was assessed in vitro by testing the proliferation and the osteogenic differentiation of human adipose stem cell (hASCs) for two weeks.

Results

The designed hydrogel layer could withstand cyclic compression and protected the brittle internal core of the ceramic. The hydrogel coating modulated the diffusion of the model protein BSA according to the degree of crosslinking of the hydrogel layer. Additionally, the polymeric network was able to retain positively charged proteins such as lysozyme due to the strong electrostatic interactions with carboxylic groups of alginate. A higher expression of alkaline phosphates activity was found on hASCs seeded on the coated scaffolds compared to the hydrogels without any β-TCP.

Conclusion

Overall, the hydrogel coating characterized in this study represents a valid strategy to overcome limitations of brittle ceramic-based materials used as scaffolds for bone tissue engineering applications.

Effects of polycaprolactone on alendronate drug release from Mg-doped hydroxyapatite coating on titanium

The scientific objective of this study was to understand the influence of PCL coating on alendronate drug release kinetics in vitro. Our hypothesis was PCL coating would minimize burst release of alendronate from plasma sprayed Mg-doped hydroxyapatite (HA) coated commercially pure titanium (CpTi) samples. In the US alone, over 44 million women and men aged 50 and older are affected by osteoporosis which can lead to replacement and/or revision surgeries. Alendronate is a widely-used drug for treating osteoporosis and would be an ideal drug to be loaded and released from these replacement systems. Initial burst release is a common phenomenon for the most drug loaded devices. To modulate the release kinetics, a biodegradable polymer, polycaprolactone (PCL), coating with slow degradable kinetics was employed. Samples with 2 and 4 wt% PCL showed about 34% and 26% release of alendronate within the first 24 h, respectively, compared to 75% burst release without any PCL coating. With the addition of a PCL coating, a controlled release kinetics of alendronate was achieved from HA coated titanium implants, which can potentially impact millions of patients worldwide having compromised bone due to osteoporosis.

Poly-epsilon-caprolactone nanoparticles enhance ursolic acid in vivo efficacy against Trypanosoma cruzi infection

Despite affecting millions of people worldwide, Chagas disease is still neglected by the academia and industry and the therapeutic option available, benznidazole, presents limited efficacy and side effects. Within this context, ursolic acid may serve as an option for treatment, however has low bioavailability, which can be enhanced through the encapsulation in polymeric nanoparticles. Therefore, herein we developed ursolic acid-loaded nanoparticles with poly-ε-caprolactone by the nanoprecipitation method and characterized them for particle size, zeta potential, polydispersity, encapsulation efficiency, morphology by scanning electron microscopy and thermal behavior by differential scanning calorimetry. Results indicated that an appropriate ratio of organic phase/aqueous phase and polymer/drug is necessary to produce smaller particles, with low polydispersity, negative zeta potential and high drug encapsulation efficiency. In vitro studies indicated the safety of the formulation against fibroblast culture and its efficacy in killing T. cruzi. Very importantly, the in vivo study revealed that the ursolic acid-loaded nanoparticle is as potent as the benznidazole group to control parasitemia, which could be attributed to improved bioavailability of the encapsulated drug. Finally, the toxicity evaluation showed that while benznidazole group caused liver toxicity, the nanoparticles were safe, indicating that this formulation is promising for future evaluation.

Graphene oxide-enhanced sol-gel transition sensitivity and drug release performance of an amphiphilic copolymer-based nanocomposite

We report the fabrication of a highly sensitive amphiphilic copolymer-based nanocomposite incorporating with graphene oxide (GO), which exhibited a low-intensity UV light-triggered sol-gel transition. Non-cytotoxicity was observed for the composite gels after the GO incorporation. Of particular interest were the microchannels that were formed spontaneously within the GO-incorporated UV-gel, which expedited sustained drug release. Therefore, the present highly UV-sensitive, non-cytotoxic amphiphilic copolymer-based composites is expected to provide enhanced photothermal therapy and chemotherapy by means of GO's unique photothermal properties, as well as through efficient passive targeting resulting from the sol-gel transition characteristic of the copolymer-based system with improved sensitivity, which thus promises the enhanced treatment of patients with cancer and other diseases.

Electrospun polycaprolactone nanofibers as a potential oromucosal delivery system for poorly water-soluble drugs

The number of poorly water-soluble drug candidates is rapidly increasing; this represents a major challenge for the pharmaceutical industry. As a consequence, novel formulation approaches are required. Furthermore, if such a drug candidate is intended for the therapy of a specific group of the population, such as geriatric or pediatric, the formulation challenge is even greater, with the need to produce a dosage form that is acceptable for specific patients. Therefore, the goal of our study was to explore electrospun polycaprolactone (PCL) nanofibers as a novel nanodelivery system adopted for the oromucosal administration of poorly water-soluble drugs. The nanofibers were evaluated in comparison with polymer films loaded with ibuprofen or carvedilol as the model drugs. Scanning electron microscopy revealed that the amount of incorporated drug affects the diameter and the morphology of the nanofibers. The average fiber diameter increased with a higher drug loading, whereas the morphology of the nanofibers was noticeably changed in the case of nanofibers with 50% and 60% ibuprofen. The incorporation of drugs into the electrospun PCL nanofibers was observed to reduce their crystallinity. Based on the morphology of the nanofibers and the films, and the differential scanning calorimetry results obtained in this study, it can be assumed that the drugs incorporated into the nanofibers were partially molecularly dispersed in the PCL matrix and partially in the form of dispersed nanocrystals. The incorporation of both model drugs into the PCL nanofibers significantly improved their dissolution rates. The PCL nanofibers released almost 100% of the incorporated ibuprofen in 4h, whereas only up to 77% of the incorporated carvedilol was released during the same time period, indicating the influence of the drug's properties, such as molecular weight and solubility, on its release from the PCL matrix. The obtained results clearly demonstrated the advantages of the new nanodelivery system compared to the drug-loaded polymer films that were used as the reference formulation. As a result, electrospinning was shown to be a very promising nanotechnology-based approach to the formulation of poorly water-soluble drugs in order to enhance their dissolution. In addition, the great potential of the produced drug-loaded PCL nanofiber mats for subsequent formulation as oromucosal drug delivery systems for children and the elderly was confirmed.

Polycaprolactone-coated 3D printed tricalcium phosphate scaffolds for bone tissue engineering: in vitro alendronate release behavior and local delivery effect on in vivo osteogenesis

The aim of this work was to evaluate the effect of in vitro alendronate (AD) release behavior through polycaprolactone (PCL) coating on in vivo bone formation using PCL-coated 3D printed interconnected porous tricalcium phosphate (TCP) scaffolds. Higher AD and Ca(2+) ion release was observed at lower pH (5.0) than that at higher pH (7.4). AD and Ca(2+) release, surface morphology, and phase analysis after release indicated a matrix degradation dominated AD release caused by TCP dissolution. PCL coating showed its effectiveness for controlled and sustained AD release. Six different scaffold compositions, namely, (i) TCP (bare TCP), (ii) TCP + AD (AD-coated TCP), (iii) TCP + PCL (PCL-coated TCP), (iv) TCP + PCL + AD, (v) TCP + AD + PCL, and (vi) TCP + AD + PCL + AD were tested in the distal femoral defect of Sprague-Dawley rats for 6 and 10 weeks. An excellent bone formation inside the micro and macro pores of the scaffolds was observed from histomorphology. Histomorphometric analysis revealed maximum new bone formation in TCP + AD + PCL scaffolds after 6 weeks. No adverse effect of PCL on bioactivity of TCP and in vivo bone formation was observed. All scaffolds with AD showed higher bone formation and reduced TRAP (tartrate resistant acid phosphatase) positive cells activity compared to bare TCP and TCP coated with only PCL. Bare TCP scaffolds showed the highest TRAP positive cells activity followed by TCP + PCL scaffolds, whereas TCP + AD scaffolds showed the lowest TRAP activity. A higher TRAP positive cells activity was observed in TCP + AD + PCL compared to TCP + AD scaffolds after 6 weeks. Our results show that in vivo local AD delivery from PCL-coated 3DP TCP scaffolds could further induce increased early bone formation.