Impact of polymer hydrophilicity on biocompatibility: implication for DES polymer design

Unraveling and Harnessing the Immune Response at the Cell-Biomaterial Interface for Tissue Engineering Purposes

Biomaterials are defined as "engineered materials" and include a range of natural and synthetic products, designed for their introduction into and interaction with living tissues. Biomaterials are considered prominent tools in regenerative medicine that support the restoration of tissue defects and retain physiologic functionality. Although commonly used in the medical field, these constructs are inherently foreign toward the host and induce an immune response at the material-tissue interface, defined as the foreign body response (FBR). A strong connection between the foreign body response and tissue regeneration is suggested, in which an appropriate amount of immune response and macrophage polarization is necessary to trigger autologous tissue formation. Recent developments in this field have led to the characterization of immunomodulatory traits that optimizes bioactivity, the integration of biomaterials and determines the fate of tissue regeneration. This review addresses a variety of aspects that are involved in steering the inflammatory response, including immune cell interactions, physical characteristics, biochemical cues, and metabolomics. Harnessing the advancing knowledge of the FBR allows for the optimization of biomaterial-based implants, aiming to prevent damage of the implant, improve natural regeneration, and provide the tools for an efficient and successful in vivo implantation.

Mechanically suitable and osteoinductive 3D-printed composite scaffolds with hydroxyapatite nanoparticles having diverse morphologies for bone tissue engineering

The challenge of integrating hydroxyapatite nanoparticles (nHAp) with polymers is hindered by the conflict between the hydrophilic and hygroscopic properties of nHAp and the hydrophobic properties of polymers. This conflict particularly affects the materials when calcium phosphates, including nHAp, are used as a filler in composites in thermal processing applications such as 3D printing with fused filament fabrication (FFF). To overcome this, we propose a one-step surface modification of nHAp with calcium stearate monolayer. Moreover, to build the scaffold with suitable mechanical strength, we tested the addition of nHAp with diverse morphology-spherical, plate- and rod-like nanoparticles. Our analysis showed that the composite of polycaprolactone (PCL) reinforced with nHAp with rod and plate morphologies modified with calcium stearate monolayer exhibited a significant increase in compressive strength. However, composites with spherical nHAp added to PCL showed a significant reduction in compressive modulus and compressive strength, but both parameters were within the applicability range of hard tissue scaffolds. None of the tested composite scaffolds showed cytotoxicity in L929 murine fibroblasts or MG-63 human osteoblast-like cells, supporting the proliferation of the latter. Additionally, PCL/nHAp scaffolds reinforced with spherical nHAp caused osteoactivation of bone marrow human mesenchymal stem cells, as indicated by alkaline phosphatase activity and COL1, RUNX2, and BGLAP expression. These results suggest that the calcium stearate monolayer on the surface of the nHAp particles allows the production of polymer/nHAp composites suitable for hard tissue engineering and personalized implant production in 3D printing using the FFF technique.

Temporal Trends in the Outcomes of Percutaneous Coronary Intervention With Zotarolimus Eluting Stents Versus Everolimus Eluting Stents: A Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Long-term follow-up results of various trials comparing Zotarolimus eluting stents (ZES) with Everolimus eluting stents (EES) have been published recently. Additionally, over the last decade, there have been new trials comparing the ZES with various commercially available EES. We aim to conduct an updated meta-analysis in light of new evidence from randomized controlled trials (RCTs) to provide comprehensive evidence regarding the temporal trends in the clinical outcomes.

METHODS

A comprehensive literature search was conducted across PubMed, Cochrane, and Embase. RCTs comparing ZES with EES for short (<2 years), intermediate (2-3 years), and long-term follow-ups (3-5 years) were included. Relative risk was used to pool the dichotomous outcomes using the random effects model employing the inverse variance method. All statistical analysis was conducted using Revman 5.4.

RESULTS

A total of 18 studies reporting data at different follow-ups for nine trials (n = 14319) were included. At short-term follow-up (<2 years), there were no significant differences between the two types of stents (all-cause death, cardiac death, Major adverse cardiovascular events (MACE), target vessel myocardial infarction, definite or probable stent thrombosis or safety outcomes (target vessel revascularization, target lesion revascularization, target vessel failure, target lesion failure). At intermediate follow-up (2-3 years), EES was superior to ZES for reducing target lesion revascularization (RR = 1.28, 95% CI = 1.05-1.58, p < 0.05). At long-term follow-up (3-5 years), there were no significant differences between the two groups for any of the pooled outcomes (p > 0.05).

CONCLUSION

ZES and EES have similar safety and efficacy at short, intermediate, and long-term follow-ups.

Bioresorbable Multilayer Organic-Inorganic Films for Bioelectronic Systems

Bioresorbable electronic devices as temporary biomedical implants represent an emerging class of technology relevant to a range of patient conditions currently addressed with technologies that require surgical explantation after a desired period of use. Obtaining reliable performance and favorable degradation behavior demands materials that can serve as biofluid barriers in encapsulating structures that avoid premature degradation of active electronic components. Here, this work presents a materials design that addresses this need, with properties in water impermeability, mechanical flexibility, and processability that are superior to alternatives. The approach uses multilayer assemblies of alternating films of polyanhydride and silicon oxynitride formed by spin-coating and plasma-enhanced chemical vapor deposition , respectively. Experimental and theoretical studies investigate the effects of material composition and multilayer structure on water barrier performance, water distribution, and degradation behavior. Demonstrations with inductor-capacitor circuits, wireless power transfer systems, and wireless optoelectronic devices illustrate the performance of this materials system as a bioresorbable encapsulating structure.

Trends in the Synthesis of Polymer Nano- and Microscale Materials for Bio-Related Applications

Polymeric nano- and microscale materials bear significant potential in manifold applications related to biomedicine. This is owed not only to the large chemical diversity of the constituent polymers, but also to the various morphologies these materials can achieve, ranging from simple particles to intricate self-assembled structures. Modern synthetic polymer chemistry permits the tuning of many physicochemical parameters affecting the behavior of polymeric nano- and microscale materials in the biological context. In this Perspective, an overview of the synthetic principles underlying the modern preparation of these materials is provided, aiming to demonstrate how advances in and ingenious implementations of polymer chemistry fuel a range of applications, both present and prospective.

Hydrophilic surface-modified 3D printed flexible scaffolds with high ceramic particle concentrations for immunopolarization-regulation and bone regeneration

Bioceramic scaffolds used in bone tissue engineering suffer from a low concentration of ceramic particles (<50 wt%), because the high concentration of ceramic particles increases the brittleness of the composite. 3D printed flexible PCL/HA scaffolds with high ceramic particle concentrations (84 wt%) were successfully fabricated in this study. However, the hydrophobicity of PCL weakens the composite scaffold hydrophilicity, which may limit the osteogenic ability to some extent. Thus, as a less time-consuming, less labour intensive, and more cost-effective treatment method, alkali treatment (AT) was employed to modify the surface hydrophilicity of the PCL/HA scaffold, and its regulation of immune responses and bone regeneration were investigated in vivo and in vitro. Initially, several concentrations of NaOH (0.5, 1, 1.5, 2, 2.5, and 5 mol L^-1) were employed in tests to determine the appropriate concentration for AT. Based on the comprehensive consideration of the results of mechanical experiments and hydrophilicity, 2 mol L^-1 and 2.5 mol L^-1 of NaOH were selected for further investigation in this study. The PCL/HA-AT-2 scaffold dramatically reduced foreign body reactions as compared to the PCL/HA and PCL/HA-AT-2.5 scaffolds, promoted macrophage polarization towards the M2 phenotype and enhanced new bone formation. The Wnt/β-catenin pathway might participate in the signal transduction underlying hydrophilic surface-modified 3D printed scaffold-regulated osteogenesis, according to the results of immunohistochemical staining. In conclusion, hydrophilic surface-modified 3D printed flexible scaffolds with high ceramic particle concentrations can regulate the immune reactions and macrophage polarization to promote bone regeneration, and the PCL/HA-AT-2 scaffold is a potential candidate for bone tissue repair.

Modulating neuroinflammation through molecular, cellular and biomaterial-based approaches to treat spinal cord injury

The neuroinflammatory response that is elicited after spinal cord injury contributes to both tissue damage and reparative processes. The complex and dynamic cellular and molecular changes within the spinal cord microenvironment result in a functional imbalance of immune cells and their modulatory factors. To facilitate wound healing and repair, it is necessary to manipulate the immunological pathways during neuroinflammation to achieve successful therapeutic interventions. In this review, recent advancements and fresh perspectives on the consequences of neuroinflammation after SCI and modulation of the inflammatory responses through the use of molecular-, cellular-, and biomaterial-based therapies to promote tissue regeneration and functional recovery will be discussed.

A novel polymer-free everolimus-eluting stent with a nitrogen-doped titanium dioxide film inhibits restenosis and thrombosis in a swine coronary model

BACKGROUND

Short-term outcomes regarding the safety and efficacy of a polymer-free everolimus-eluting stent (EES) with a nitrogen-doped titanium dioxide (N-TiO₂) film in a swine coronary model have been reported. However, the long-term results of the use of this type of stent have not yet been evaluated or compared to those of other polymer-free coronary stents. Therefore, this study aimed to determine the mid- to long-term safety and efficacy of a polymer-free EES with an N-TiO₂ film in a swine coronary model.

METHODS

Polymer-free EES with N-TiO₂ films (n = 30) and polymer-free sirolimus-eluting stents (SES; n = 30) were implanted in 30 pigs. Quantitative coronary analysis and optical coherence tomography were conducted immediately and at 1 (quantitative coronary analysis only), 3, and 6 months after stenting. Histopathologic examinations were performed at 1, 3, and 6 months after stenting.

RESULTS

The polymer-free EES group had a lower percentage of neointimal growth than the polymer-free SES group at 3 months (22.5% ± 11.4% vs. 32.1% ± 12.3%; p < 0.001). The polymer-free EES group had a lower fibrin score than the polymer-free SES group at 1 month (1.9 ± 0.45 vs. 2.5 ± 0.54; p = 0.001). The re-endothelialization rates were similar between groups. The polymer-free EES group had a lower percentage of the area of stenosis than the polymer-free SES group throughout the follow-up period.

CONCLUSIONS

The novel polymer-free EES with an N-TiO₂ film has superior safety and efficacy than the polymer-free SES at the 6-month follow-up in a swine model.

Facile method to synthesize fluorescent chitosan hydrogels for selective detection and adsorption of Hg2+/Hg. Carbohydr Polym 2022;288:119417. [PMID: 35450660 DOI: 10.1016/j.carbpol.2022.119417]

Fluorescent chitosan-based hydrogel for the selective detection and adsorption of Hg²⁺/Hg⁺ in aqueous environment was prepared through three-step synthesis strategy. NO₂-Boron-dipyrrolemethene (BODIPY) was prepared firstly, and then the -NO₂ group was reduced to -NH₂ group. Finally, the NH₂-BODIPY was introduced to chitosan by Schiff base formation reaction through bi-aldehyde. Eventually, fluorescent chitosan hydrogel was obtained. The as-prepared fluorescent hydrogel probe could detect Hg²⁺/Hg⁺ through PET mechanism with the detection limit of 0.3 μM. The recognition site which combines Hg²⁺/Hg⁺ is CN, it is just formed in the reaction with chitosan and the amino group on BODIPY. Adsorption capacity of the fluorescent hydrogel is 121 mg·g^-1, which is almost seven times of the original chitosan. The isotherm and kinetics of Hg²⁺/Hg⁺ removal follows Langmuir isotherm and pseudo-second order kinetics, respectively. Besides, a series of fluorescent hydrogels were prepared to compare the elasticity, hydropHilicity, fluorescence intensity and adsorption capacity.

Pore Size of 3D-Printed Polycaprolactone/Polyethylene Glycol/Hydroxyapatite Scaffolds Affects Bone Regeneration by Modulating Macrophage Polarization and the Foreign Body Response

3D-printed porous bioactive ceramic scaffolds have been widely used in bone defect repair. However, material implantation is often accompanied by a foreign body response (FBR), which may affect host tissue regeneration. The physical properties of biomaterials, including shape, pore size, and porosity, control the relevant immune responses during tissue regeneration. To the best of our knowledge, the effect of the pore size of 3D-printed scaffolds on the immune response and bone-biomaterial integration has not been studied in vivo. Polycaprolactone/polyethylene glycol/hydroxyapatite (PCL/PEG/HA) bioactive scaffolds with different pore sizes, including 209.9 ± 77.1 μm (P200), 385.5 ± 28.6 μm (P400), and 582.1 ± 27.2 μm (P600), were prepared with a pneumatic extrusion 3D printer. Compared with other pore sizes, P600 significantly reduced the FBR and induced more M2 macrophage infiltration, vascular ingrowth, and new bone formation. Immunohistochemical staining revealed that the MyD88 protein might be involved in macrophage polarization-related signal transduction in response to the pore size. Based on these results, bone regeneration requires the active participation of the immune response, and the P600 PCL/PEG/HA scaffold is a preferable candidate for the repair of bone defects.

Bioactive Synthetic Polymers

Synthetic polymers are omnipresent in society as textiles and packaging materials, in construction and medicine, among many other important applications. Alternatively, natural polymers play a crucial role in sustaining life and allowing organisms to adapt to their environments by performing key biological functions such as molecular recognition and transmission of genetic information. In general, the synthetic and natural polymer worlds are completely separated due to the inability for synthetic polymers to perform specific biological functions; in some cases, synthetic polymers cause uncontrolled and unwanted biological responses. However, owing to the advancement of synthetic polymerization techniques in recent years, new synthetic polymers have emerged that provide specific biological functions such as targeted molecular recognition of peptides, or present antiviral, anticancer, and antimicrobial activities. In this review, the emergence of this generation of bioactive synthetic polymers and their bioapplications are summarized. Finally, the future opportunities in this area are discussed.

Fluorescent dialdehyde-BODIPY chitosan hydrogel and its highly sensing ability to Cu2+ ion

Fluorescent hydrogel with proper hydrophilicity and thermal stability, excellent sensitivity and high selectivity has important practical and scientific significance, especially in heavy metal ion detection. In this work, by adjusting the content of [2, 6-Bis-[4-formylthiophene]]-1,3,5,7-tetramethyl-8-phenyl-4, 4-difluoroborazaindoloene (B3), as a cross-linking agent, a series of chitosan- fluoroboron dipyrrole-chitosan-based fluorescent hydrogels (CBC) with large stokes shift were designed and prepared. The hydrogels can be used as fluorescent probes for identifying Cu²⁺ in aqueous solution. The linear quenching range of Cu²⁺ is 0-50 μM, and the detection limit and quenching constant are 4.75 μM and 3.52 × 10⁴ M^-1, respectively. Under the interaction of Cu²⁺, the imine bond CN was converted to C- N bond, which causes the phenomenon of fluorescence quenching. In addition, relatively high crosslink density improves hydrophilicity and thermal stability of initial chitosan, and made the swelling ability better.

Clinical outcomes in 2481 unselected real-world patients treated with a polymer-free sirolimus-eluting stent: 3 years results from the NANO multicenter Registry

OBJECTIVES

To evaluate the 3-year clinical outcomes of a polymer-free sirolimus-eluting, Nano plus stent for the treatment of coronary artery disease in the NANO multicenter Registry.

BACKGROUND

The long-term clinical data evaluating the safety and efficacy of the novel polymer-free sirolimus-eluting Nano plus stent (Lepu Medical, Beijing, China) is limited.

METHODS

The NANO all-comers Registry trial was a prospective, multicenter clinical registry conducted in 26 centers in China between August 2016 and January 2017. A total of 2481 consecutive patients were exclusively treated with the Nano plus stent. The primary clinical endpoint, target lesion failure (TLF, defined as cardiac death, target vessel nonfatal myocardial infarction, and clinically driven target lesion revascularization [CD-TLR]), was analyzed at 3 years.

RESULTS

At 3 years, 2295 patients (92.5%) were followed. The incidence of TLF was 6.8% (168/2481). The rate of cardiac death was 3.8% (94/2481), target vessel nonfatal myocardial infarction 0.7% (18/2481), and CD-TLR 2.9% (68/2481). The rate of definite/probable stent thrombosis was 0.5% (13/2481). The risk factors of diabetes mellitus, acute myocardial infarction, age, chronic renal failure, in-stent restenosis, chronic total occlusion, and left ventricular ejection fraction < 40% were the independent predictors of 3-year TLF.

CONCLUSIONS

At three years, the rate of TLF was relatively low in patients treated with the polymer-free Nano plus stent. The polymer-free Nano plus stent showed a favorable safety and efficacy profile in real-world patients. Clinical trial registration URL: https://www.clinicaltrials.gov/ . Unique identifier: NCT02929030.

The antigenicity of silk-based biomaterials: sources, influential factors and applications

Silk is an ancient material with essential roles in numerous biomedical applications, such as tissue regeneration and drug delivery, because of its excellent tunable mechanical properties and diverse physical structures. In addition to the necessary functionalities for biomedical applications, another critical factor for materials applied in biology is the appropriate immune interactions with the body. This review focuses on the immune responses of silk-based materials applied in biomedical applications, specifically antigenicity. The factors affecting the antigenicity of silk-based materials are complicated and are related to the composition and structural characteristics of the materials. At the same time, the composition of silk-based materials varies with its species sources, such as silkworms, spiders, honey bees, or engineered recombinant silk. Additionally, different processing methods are used to fabricate different material formats, such as films, hydrogels, scaffolds, particles, and fibers, resulting in different structural characteristics. Furthermore, the resulting body reactions are also different with different degrees of the immune response. Silk protein typically induces a mild immune response, and immunogenicity can play active roles in osteogenesis, angiogenesis, and protection from inflammation. However, there are some rare reports of severe immune responses caused by silk, which can result in an allergic response or tissue necrosis. The source of allergenicity in silk-based materials is currently under-studied and how to regulate and eliminate the overreaction of the immune system is essential for further applications. Overall, the diverse characteristics of silk-based materials mostly show beneficial bioresponses with mild immunogenicity, and the tunable properties make it applicable in immune-related biomedical applications.

Strontium-Loaded Nanotubes of Ti-24Nb-4Zr-8Sn Alloys for Biomedical Implantation

Ti-24Nb-4Zr-8Sn (Ti2448) alloys, with a relatively low elastic modulus and unique mechanical properties, are desirable materials for oral implantation. In the current study, a multifaceted strontium-incorporating nanotube coating was fabricated on a Ti2448 alloy (Ti2-NTSr) through anodization and hydrothermal procedures. In vitro, the Ti2-NTSr specimens demonstrated better osteogenic properties and more favorable osteoimmunomodulatory abilities. Moreover, macrophages on Ti2-NTSr specimens could improve the recruitment and osteogenic differentiation of osteoblasts. In vivo, dense clots with highly branched, thin fibrins and small pores existed on the Ti2-NTSr implant in the early stage after surgery. Analysis of the deposition of Ca and P elements, hard tissue slices and the bone-implant contact rate (BIC%) of the Ti2-NTSr implants also showed superior osseointegration. Taken together, these results demonstrate that the Ti2-NTSr coating may maximize the clinical outcomes of Ti2448 alloys for implantation applications.

Hybrid interpenetrating hydrogel network favoring the bidirectional migration of tenocytes for rotator cuff tendon regeneration

Replenishment of tenocytes to the injury site is an ideal strategy to improve healing response and accelerate the tendon ECM regeneration. The present study focused on the synthesis and characterization of a hybrid hydrogel scaffold system poly(propylene-fumarate)-alginate-polyvinyl alcohol-acrylic acid (PAPA) using poly(propylene-fumarate) (PPF), alginate, polyvinyl alcohol (PVA) and acrylic acid and the in vitro investigation of bidirectional mobility of swine shoulder tenocytes (SST) for its potential application in rotator-cuff tendon regeneration. IR analysis revealed the presence of alginate, PPF and PVA segments on the surface, SEM and AFM analyses revealed the porous and nano-topographical features of PAPA, respectively, swelling was 712.6 ± 84.21% with the EWC (%) of 87.59 ± 1.26 having the diffusional exponent and swelling constant 0.551 and 1.8, respectively. PAPA was biodegradable, cytocompatible and supported long-term survival of SSTs. SEM imaging revealed the adhesion, colonization, and sheet formation of SSTs within the PAPA hydrogel network. The SSTs seeded on the PAPA scaffolds were peculiar for their bidirectional migration as the anterograde movement was completed in 9 days whereas the retrograde infiltration occurred up to the depth of 198 μm. These findings suggest the promising translational potential of PAPA scaffold system in the management of rotator cuff tendon injury.

Comparison of acute thrombogenicity and albumin adsorption in three different durable polymer coronary drug-eluting stents

BACKGROUND

The relative thrombogenicity and albumin adsorption and retention of different durable polymers used in coronary stents has not been tested.

AIMS

This study sought to compare the thromboresistance and albumin binding capacity of different durable polymer drug-eluting stents (DES) using dedicated preclinical and in vitro models.

METHODS

In an ex vivo swine arteriovenous shunt model, a fluoropolymer everolimus-eluting stent (FP-EES) (n=14) was compared with two durable polymer DES, the BioLinx polymer-coated zotarolimus-eluting stent (BL-ZES) (n=9) and a CarboSil elastomer polymer-coated ridaforolimus-eluting stent (EP-RES) (n=6), and bare metal stents (BMS) (n=10). Stents underwent immunostaining using a cocktail of antiplatelet antibodies and a marker for inflammation and were then evaluated by confocal microscopy (CM). Albumin retention was assessed using a flow loop model with labelled human serum albumin (FP-EES [n=8], BL-ZES [n=4], EP-RES [n=4], and BMS [n=7]), and scanned by CM.

RESULTS

The area of platelet adherence (normalised to total stent surface area) was lower in the order FP-EES (9.8%), BL-ZES (32.7%), EP-RES (87.6%) and BMS (202.0%), and inflammatory cell density was least for FP-EES <BL-ZES <EP-RES <BMS. Although nearly full coverage by albumin binding was shown for all durable polymer DES, FP-EES showed significantly greater intensity of albumin as compared to BL-ZES, EP-RES and BMS (FP-EES 79.0%; BL-ZES 13.2%; EP-RES 6.1%; BMS 1.5%).

CONCLUSIONS

These results suggest that thromboresistance and albumin retention vary by polymer type and that these differences might result in different suitability for short-term dual antiplatelet therapy.

Promoting musculoskeletal system soft tissue regeneration by biomaterial-mediated modulation of macrophage polarization

Musculoskeletal disorders are common in clinical practice. Repairing critical-sized defects in musculoskeletal systems remains a challenge for researchers and surgeons, requiring the application of tissue engineering biomaterials. Successful application depends on the response of the host tissue to the biomaterial and specific healing process of each anatomical structure. The commonly-held view is that biomaterials should be biocompatible to minimize local host immune response. However, a growing number of studies have shown that active modulation of the immune cells, particularly macrophages, via biomaterials is an effective way to control immune response and promote tissue regeneration as well as biomaterial integration. Therefore, we critically review the role of macrophages in the repair of injured musculoskeletal system soft tissues, which have relatively poor regenerative capacities, as well as discuss further enhancement of target tissue regeneration via modulation of macrophage polarization by biomaterial-mediated immunomodulation (biomaterial properties and delivery systems). This active regulation approach rather than passive-evade strategy maximizes the potential of biomaterials to promote musculoskeletal system soft tissue regeneration and provides alternative therapeutic options for repairing critical-sized defects.

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Different phenotypes of macrophages play a crucial role in musculoskeletal system soft tissue regeneration.

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Biomaterials and biomaterial-based delivery systems can be utilized to modulate macrophage polarization.

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This review summarizes immunomodulatory biomaterials to spur musculoskeletal system soft tissue regeneration.

Effects of simulated COVID-19 cytokine storm on stent thrombogenicity

Background

Cytokine storm-related hypercoagulation may be important in the pathogenesis of stent thrombosis in patients with SARS-CoV-2. Whether stent polymers behave differently under such conditions has never been explored.

Methods

Fluorinated polymer-nanocoated and uncoated COBRA stents (CeloNova), BioLinx-polymer-coated Resolute Onyx stents (Medtronic), and Synergy stents (Boston Scientific), which are abluminally coated with a bioabsorbable polymer, were exposed to human blood from healthy donors which was supplemented with 400 pg/mL IL-6 and 100 pg/mL TNF-α, similar to what is seen in cytokine storm caused by SARS-CoV-2. Platelet adhesion and neutrophil activation, assessed by immunofluorescence, were compared under cytokine storm and control conditions (untreated blood) (n = 4 experimental runs).

Results

Platelet adhesion values, defined as %platelet-covered area x staining intensity, were significantly lower in coated and uncoated COBRA and in Resolute Onyx than in Synergy under control conditions (1.28 × 10⁷ ± 0.43 × 10⁷ vs. 2.92 × 10⁷ ± 0.49 × 10⁷ vs. 3.57 × 10⁷ ± 0.73 × 10⁷ vs. 9.94 × 10⁷ ± 0.99 × 10⁷; p ≤0.0001). In cytokine storm, platelet adhesion values remained low in coated COBRA-PzF (1.78 × 10⁷ ± 0.38 × 10⁷) compared to all other devices (uncoated COBRA: 5.92 × 10⁷ ± 0.96 × 10⁷; Resolute Onyx: 7.27 × 10⁷ ± 1.82 × 10⁷; Synergy: 11.28 × 10⁷ ± 1.08 × 10⁷; p ≤ 0.0001). Although cytokine storm conditions significantly increased neutrophil activation in all stents, it was significantly less in coated and uncoated COBRA, and in Resolute Onyx than in Synergy.

Conclusions

Blood-biomaterials interactions may determine the thrombogenic potential of stents. Under simulated cytokine storm conditions, fluoropolymer-coated stents showed the most favorable anti-thrombogenic and anti-inflammatory properties.

The State of the Art and Prospects for Osteoimmunomodulatory Biomaterials

The critical role of the immune system in host defense against foreign bodies and pathogens has been long recognized. With the introduction of a new field of research called osteoimmunology, the crosstalk between the immune and bone-forming cells has been studied more thoroughly, leading to the conclusion that the two systems are intimately connected through various cytokines, signaling molecules, transcription factors and receptors. The host immune reaction triggered by biomaterial implantation determines the in vivo fate of the implant, either in new bone formation or in fibrous tissue encapsulation. The traditional biomaterial design consisted in fabricating inert biomaterials capable of stimulating osteogenesis; however, inconsistencies between the in vitro and in vivo results were reported. This led to a shift in the development of biomaterials towards implants with osteoimmunomodulatory properties. By endowing the orthopedic biomaterials with favorable osteoimmunomodulatory properties, a desired immune response can be triggered in order to obtain a proper bone regeneration process. In this context, various approaches, such as the modification of chemical/structural characteristics or the incorporation of bioactive molecules, have been employed in order to modulate the crosstalk with the immune cells. The current review provides an overview of recent developments in such applied strategies.

A new hydrophilic biodegradable ureteral stent restrain encrustation both in vitro and in vivo

Ureteral stents have been widely used as biomedical devices to treat some urological diseases for several decades. However, the encrustation complications hamper the long-time clinical use of the ureteral stents. In this work, a new type of biodegradable material for the ureteral stents, methoxypoly(ethylene glycol)-block-poly(L-lactide-ran-Ɛ-caprolactone) (mPEG-PLACL), is evaluated to overcome this problem. The results show that the hydrophilicity and degradation rate in artificial urine of mPEG-PLACL are both significantly increased. It is worth noting that the mPEG-PLACL shows a lower amount of encrustation after immersing the stents in the dynamic urinary extracorporeal circulation (DUEC) model for 7 days. In addition, 71% Ca and 92% Mg are inhibited in vivo by quantitative analysis. Pathological analysis exhibit that the mPEG-PLACL cause less diffuse mucosal hyperplasia after 7 weeks of implantation. All the results indicate that this new type of biodegradable material had an excellent potential for the ureteral stents in the future.

Is Viral Vector Gene Delivery More Effective Using Biomaterials?

Gene delivery has been extensively investigated for introducing foreign genetic material into cells to promote expression of therapeutic proteins or to silence relevant genes. This approach can regulate genetic or epigenetic disorders, offering an attractive alternative to pharmacological therapy or invasive protein delivery options. However, the exciting potential of viral gene therapy has yet to be fully realized, with a number of clinical trials failing to deliver optimal therapeutic outcomes. Reasons for this include difficulty in achieving localized delivery, and subsequently lower efficacy at the target site, as well as poor or inconsistent transduction efficiency. Thus, ongoing efforts are focused on improving local viral delivery and enhancing its efficiency. Recently, biomaterials have been exploited as an option for more controlled, targeted and programmable gene delivery. There is a growing body of literature demonstrating the efficacy of biomaterials and their potential advantages over other delivery strategies. This review explores current limitations of gene delivery and the progress of biomaterial-mediated gene delivery. The combination of biomaterials and gene vectors holds the potential to surmount major challenges, including the uncontrolled release of viral vectors with random delivery duration, poorly localized viral delivery with associated off-target effects, limited viral tropism, and immune safety concerns.

Amphiphilic polymeric nanoparticles encapsulating curcumin: Antioxidant, anti-inflammatory and biocompatibility studies

Oxidative stress and inflammation are two related processes common to many diseases. Curcumin is a natural compound with both antioxidant and anti-inflammatory properties, among others, that is recently being used as a natural occurring product alternative to traditional drugs. However, it has a hydrophobic nature that compromises its solubility in physiological fluids and its circulation time and also presents cytotoxicity problems in its free form, limiting the range of concentrations to be used. In order to overcome these drawbacks and taking advantage of the benefits of nanotechnology, the aim of this work is the development of curcumin loaded polymeric nanoparticles that can provide a controlled release of the drug and enlarge their application in the treatment of inflammatory and oxidative stress related diseases. Specifically, the vehicle is a bioactive terpolymer based on a α-tocopheryl methacrylate, 1-vinyl-2-pyrrolidone and N-vinylcaprolactam. Nanoparticles were obtained by nanoprecipitation and characterized in terms of size, morphology, stability, encapsulation efficiency and drug release. In vitro cellular assays were performed in human articular chondrocyte and RAW 264.7 cultures to assess cytotoxicity, cellular uptake, antioxidant and anti-inflammatory properties. The radical scavenging activity of the systems was confirmed by the DPPH test and the quantification of cellular reactive oxygen species. The anti-inflammatory potential of these systems was demonstrated by the reduction of different pro-inflammatory factors such as IL-8, MCP and MIP in chondrocytes; and nitric oxide, IL-6, TNF-α and MCP-1, among others, in RAW 264.7. Finally, the in vivo biocompatibility was confirmed in a rat model by subcutaneously injecting the nanoparticle dispersions. The reduction of curcumin toxicity and the antioxidant, anti-inflammatory and biocompatibility properties open the door to deeper in vitro and in vivo research on these curcumin loaded polymeric nanoparticles to treat inflammation and oxidative stress based diseases.

Design and fabrication of polycaprolactone/gelatin composite scaffolds for diaphragmatic muscle reconstruction

Diaphragmatic wall defects caused by congenital disorders or disease remain a major challenge for physicians worldwide. Polymeric patches have been extensively explored within research laboratories and the clinic for soft tissue and diaphragm reconstruction. However, patch usage may be associated with allergic reaction, infection, granulation, and recurrence of the hernia. In this study, we designed and fabricated a porous scaffold using a combination of 3D printing and freeze-drying techniques. A 3D printed polycaprolactone (PCL) mesh was used to reinforcegelatin scaffolds, representing an advantage over previously reported examples since it provides mechanical strength and flexibility. In vitro studies showed that adherent cells were anchorage-dependent and grew as a monolayer attached to the scaffolds. Microscopic observations indicated better cell attachments for the scaffolds with higher gelatin content as compared with the PCL control samples. Tensile testing demonstrated the mechanical strength of samples was significantly greater than adult diaphragm tissue. The biocompatibility of the specimens was investigated in vivo using a subcutaneous implantation method in Bagg albino adult mice for 20 days, with the results indicating superior cellular behavior and attachment on scaffolds containing gelatin in comparison to pure PCL scaffolds, suggesting that the porous PCL/gelatin scaffolds have potential as biodegradable and flexible constructs for diaphragm reconstruction.

Histopathologic response after hydrophilic polyethylene glycol-coating stent and hydrophobic octadecylthiol-coating stent implantations in porcine coronary restenosis model

Device-related problems of drug-eluting stents, including stent thrombosis related to antiproliferative drugs and polymers, can cause adverse events such as inflammation and neointimal hyperplasia. Stent surface modification, wherein the drug and polymer are not required, may overcome these problems. We developed hydrophilic polyethylene glycol (PEG)-coating and hydrophobic octadecylthiol (ODT)-coating stents without a drug and polymer and evaluated their histopathologic response in a porcine coronary restenosis model. PEG-coating stents (n = 12), bare-metal stents (BMS) (n = 12), and ODT-coating stents (n = 10) were implanted with oversizing in 34 porcine coronary arteries. Four weeks later, the histopathologic response, arterial injury, inflammation, and fibrin scores were analyzed. A p value < 0.05 was considered statistically significant. There were significant differences in the internal elastic lamina area, lumen area, neointimal area, percent area of stenosis, arterial injury score, inflammation score, and fibrin score among the groups. Compared to the BMS or ODT-coating stent group, the PEG-coating stent group had significantly increased internal elastic lamina and lumen area (all p < 0.001) and decreased neointimal area and percent area of stenosis (BMS: p = 0.03 and p < 0.001, respectively; ODT-coating: p = 0.013 and p < 0.001, respectively). Similarly, the PEG-coating group showed significantly lower inflammation and fibrin scores than the BMS or ODT-coating groups (BMS: p = 0.013 and p = 0.007, respectively; ODT-coating: p = 0.014 and p = 0.008, respectively). In conclusion, hydrophilic PEG-coating stent implantation was associated with lower inflammatory response, decreased fibrin deposition, and reduced neointimal hyperplasia than BMS or hydrophobic ODT-coating stent implantation in the porcine coronary restenosis model.

Artificial Intelligence Aided Design of Microtextured Surfaces: Application to Controlling Wettability

Artificial intelligence (AI) has emerged as a powerful set of tools for engineering innovative materials. However, the AI-aided design of materials textures has not yet been researched in depth. In order to explore the potentials of AI for discovering innovative biointerfaces and engineering materials surfaces, especially for biomedical applications, this study focuses on the control of wettability through design-controlled hierarchical surfaces, whose design is supported and its performance predicted thanks to adequately structured and trained artificial neural networks (ANN). The authors explain the creation of a comprehensive library of microtextured surfaces with well-known wettability properties. Such a library is processed and employed for the generation and training of artificial neural networks, which can predict the actual wetting performance of new design biointerfaces. The present research demonstrates that AI can importantly support the engineering of innovative hierarchical or multiscale surfaces when complex-to-model properties and phenomena, such as wettability and wetting, are involved.

Physical Properties and Biofunctionalities of Bioactive Root Canal Sealers In Vitro

Calcium silicate-based bioactive glass has received significant attention for use in various biomedical applications due to its excellent bioactivity and biocompatibility. However, the bioactivity of calcium silicate nanoparticle-incorporated bioactive dental sealer is not much explored. Herein, three commercially available bioactive root canal sealers (Endoseal MTA (EDS), Well-Root ST (WST), and Nishika Canal Sealer BG (NBG)) were compared with a resin-based control sealer (AH Plus (AHP)) in terms of physical, chemical, and biological properties. EDS and NBG showed 200 to 400 nm and 100 to 200 nm nanoparticle incorporation in the SEM image, respectively, and WST and NBG showed mineral deposition in Hank's balanced salt solution after 28 days. The flowability and film thickness of all products met the ISO 3107 standard. Water contact angle, linear dimensional changes, and calcium and silicate ion release were significantly different among groups. All bioactive root canal sealers released calcium ions, while NBG released ~10 times more silicon ions than the other bioactive root canal sealers. Under the cytocompatible extraction range, NBG showed prominent cytocompatibility, osteogenecity, and angiogenecity compared to other sealers in vitro. These results indicate that calcium silicate nanoparticle incorporation in dental sealers could be a potential strategy for dental periapical tissue regeneration.

Biodegradable β-Cyclodextrin Conjugated Gelatin Methacryloyl Microneedle for Delivery of Water-Insoluble Drug

Transdermal delivery of water-insoluble drugs via hydrogel-based microneedle (MN) arrays is crucial for improving their therapeutic efficacies. However, direct loading of water-insoluble drug into hydrophilic matrices remains challenging. Here, a biodegradable MN array patch that is fabricated from naturally derived polymer conjugates of gelatin methacryloyl and β-cyclodextrin (GelMA-β-CD) is reported. When curcumin, an unstable and water-insoluble anticancer drug, is loaded as a model drug, its stability and solubility are improved due to the formation of an inclusion complex. The polymer-drug complex GelMA-β-CD/CUR can be formulated into MN arrays with sufficient mechanical strength for skin penetration and tunable drug release profile. Anticancer efficacy of released curcumin is observed in three-dimensional B16F10 melanoma models. The GelMA-β-CD/CUR MN exhibits relatively higher therapeutic efficacy through more localized and deeper penetrated manner compared with a control nontransdermal patch. In vivo studies also verify biocompatibility and degradability of the GelMA-β-CD MN arrays patch.

Comparison of the Major Clinical Outcomes for the Use of Endeavor® and Resolute Integrity® Zotarolimus-Eluting Stents During a Three-Year Follow-up

Background

Endeavor®-zotarolimus-eluting stent (E-ZES) was the first ZES to be developed, and Resolute integrity®-ZES (I-ZES) has been developed more recently. Comparative studies on long-term usage of these two ZESs have been rare.

Objectives

The aim of this study was to compare the efficacy and safety of E-ZES and I-ZES during a long-term follow-up of patients who underwent percutaneous coronary intervention (PCI).

Methods

A total of 767 patients who underwent PCI with E-ZES or I-ZES were eligible for this study. The primary endpoint was the occurrence of major adverse cardiac events (MACEs), defined as the composite of all-cause death, non-fatal myocardial infarction (MI), and any repeat revascularization. The secondary endpoint was stent thrombosis (ST).

Results

After propensity score-matched (PSM) analysis, two PSM groups (193 pairs, n = 386, C-statistic = 0.824) were generated. During the 3-year follow-up period, the cumulative incidence of MACEs (hazard ratio [HR], 0.837; 95% confidence interval [CI], 0.464-1.508; p = 0.553) and ST (HR, 0.398; 95% CI, 0.077-2.052; p = 0.271) was similar for the E-ZES and I-ZES groups. Additionally, the cumulative incidences of all-cause death, cardiac death, non-fatal MI, and any repeat revascularization were not significantly different between the two groups.

Conclusions

Although I-ZES utilizes a more advanced stent platform, stent design, and polymer system than E-ZES, both the ZESs showed comparable efficacy and safety during the 3-year follow-up period in this single-center, all-comers registry. However, further large-scaled, randomized, well-controlled trials with long-term follow-up are needed to verify these results.

Scaffold strategies for modulating immune microenvironment during bone regeneration

Implanted bone scaffolds often fail to successfully integrate with the host tissue because they do not elicit a favorable immune reaction. Properties of bone scaffold not only provide mechanical and chemical signals to support cell adhesion, migration, proliferation and differentiation, but also play a pivotal role in determining the extent of immune response during bone regeneration. Appropriate design parameters of bone scaffold are of great significance in the process of developing a new generation of bone implants. Herein, this article addresses the recent advances in the field of bone scaffolds for immune response, particularly focusing on the physical and chemical properties of bone scaffold in manipulating the host response. Furthermore, incorporation of bioactive molecules and cells with immunoregulatory function in bone scaffolds are also presented. Finally, continuing challenges and future directions of scaffold-based strategies for modulating immune microenvironment are discussed.

Modulation of foreign body reaction and macrophage phenotypes concerning microenvironment

The foreign body reaction (FBR) is described as a local chronic inflammation after implantation of biomaterials in which macrophages involved intimately. At the stage of acute inflammation, mast cells release histamine, Interleukin-4 (IL-4) and Interleukin-13 (IL-13), enhancing recruitment, and fusion of macrophages in the following phase. As for chronic intensive inflammation, degradation of biomaterials would be promoted by macrophage-derived foreign body giant cells releasing degradative enzymes, acid and reactive oxygen intermediates. Nevertheless, it could be seen as a breakthrough point for regulating FBR, considering the dominant role of the macrophage in the immune response as exemplified by the decrease of IL-4 and IL-13, stabilizing an appropriate balance between two macrophage phenotypes, selectively suppressing some function of macrophages, and so on. Moreover, the relationship between macrophages polarization and the development of a fibrous capsule, which increase the possibility of implantation failure, will be illustrated later. This review aims at providing readers a comprehensive understanding of FBR and its correlative treatment strategy.

Plasma deposited poly-oxazoline nanotextured surfaces dictate osteoimmunomodulation towards ameliorative osteogenesis

Developing "osteoimmune-smart" bone substitute materials have become the forefront of research in bone regeneration. Biocompatible polymer coatings are applied widely to improve the bioactivity of bone substitute materials. In this context, polyoxazolines (Pox) have attracted substantial attention recently due to properties such as biocompatibility, stability, and low biofouling. In view of these useful properties, it is interesting to explore the capacity of Pox as an osteoimmunomodulatory agent to generate a favorable osteoimmune environment for osteogenesis. We applied a technique called plasma polymerization and succeeded in preparing Pox-like coatings (Ppox) and engineered their nanotopography at the nanoscale. We found that Ppox switched macrophages towards M2 extreme, thus inhibiting the release of inflammatory cytokines. The underlying mechanism may be related to the suppression of TLR pathway. The generated osteoimmune environment improved osteogenesis while inhibited osteoclastogenesis. This may be related to the release of osteogenic factors, especially Wnt10b from macrophages. The addition of nanotopography (16 nm, 38 nm, 68 nm) can tune the Ppox-mediated inhibition on inflammation and osteoclastic activities, while no significant effects were observed within the tested nano sizes on the Ppox-mediated osteogenesis. These results collectively suggest that Ppox can be useful as an effective osteoiumunomodulatory agent to endow bone substitute materials with favourable osteoimmunomodulatory property. STATEMENT OF SIGNIFICANCE: In this study, we succeeded in preparing plasma deposited Pox-like nano-coatings (Ppox) via plasma polymerization and found that Ppox nanotopographies are useful osteoimmunomodulatory tools. Their osteoimmunodolatory effects and underlying mechanisms are unveiled. It is the first investigation into the feasibility of applying poly-oxazoline as an osteoimmunomodulatory agent. This expand the application of poly-oxazoline into the forefront in bone regeneration area for the development of advanced "osteoimmune-smart" bone substitute materials.

Interactions at scaffold interfaces: Effect of surface chemistry, structural attributes and bioaffinity

Effective regenerative medicine relies on understanding the interplay between biomaterial implants and the adjoining cells. Scaffolds contribute by presenting sites for cellular adhesion, growth, proliferation, migration, and differentiation which lead to regeneration of tissues over desired periods of time. The fabrication and recruitment of scaffolds often fail to consider the interactions that occur at the interfaces, thereby risking rejection. This lack of knowledge on interfacial microenvironments and related exchanges often causes reduced cellular interactions, poor cell survival and intervention failure. Successful regenerative therapy requires scaffolds with bespoke biocompatibility, optimum pore structure, and cues for cell attachments. These factors determine the development of cellular affinity in scaffolds. For biomedical applications, a detailed understanding of scaffolds and their interfaces is required for better tuning of biomaterials to suit the microenvironments. In this review, we discuss the role of biointerfaces with a focus on surface chemistry, pore structure, scaffold hydro-affinity and their biointeractions. An understanding of the effect of scaffold interfacial properties is crucial for enhancing the progress of tissue engineering towards clinical applications.

Short-term stent coverage of second-generation zotarolimus-eluting durable polymer stents: Onyx one-month optical coherence tomography study

Introduction

To date the early strut coverage with the second-generation durable-polymer ONYX zotarolimus-eluting stent (O-ZES) is unknown.

Aim

Optical coherence tomography (OCT) assessed the strut coverage of O-ZES at thirty-day follow-up.

Material and methods

OCT was performed after implantation and at 1-month follow-up in 15 patients treated with O-ZES.

Results

Mean patient age was 67 ±7 years (73% males). The clinical presentation consisted of acute coronary syndromes (n = 13) and stable coronary disease (n = 2). Four (26%) patients had diabetes. OCT analysis was performed at baseline and 1-month follow-up in all stents. 378 cross-sections with 3582 struts were assessed at baseline and 3661 at follow-up. At follow-up, 88% struts were covered by tissue with a median thickness 37.91 μm (IQR: 22.32–64.15). Median in-stent area obstruction by neointima was 2.64% (IQR: 1.70–4.84). From the total stent covered area, 92.3% showed complete strut coverage. Homogeneous tissue was observed in 74% of cases. There were no differences in minimal lumen area (5.07 ±1.08 mm² vs. 4.81 ±0.94 mm², p = 0.125) or minimal stent area (4.95 ±1.22 mm² vs. 4.92 ±0.99 mm²) at baseline and at follow-up. There were no differences in the rate of strut malapposition (4.3% vs. 5.7%, p = 0.417). For all stents, malapposition volume was 47.9 mm³ at baseline and 51.7 mm³ at follow-up, giving the late acquired stent malapposition volume of 3.8 mm³.

Conclusions

The second-generation durable polymer O-ZES showed favorable vessel healing at 30-day OCT follow-up.

Nitric oxide releasing poly(vinylidene fluoride-co-hexafluoropropylene) films using a fluorinated nitric oxide donor to greatly decrease chemical leaching

Nitric oxide (NO) releasing polymers have been widely applied as biomaterials for a variety of biomedical implants and devices. However, the chemical leaching of NO donors and their byproduct species is almost always observed during the application of polymers doped with NO donors, unless the donor is covalently linked to the polymer. Herein, we report the first NO releasing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fluorinated copolymer prepared by incorporating a fluorinated S-nitrosothiol as the NO donor. Under physiological conditions, the resulting polymeric films can release NO for 16 days. Importantly, due to both fluorine-fluorine and electrostatic charge interactions between the fluorinated NO donor and the PVDF-HFP copolymer, the total chemical leaching of the fluorinated NO donor and its disulfide product after 9 day was only 0.6% (mol%) of the initial amount of NO donor loaded into the film. These new NO release PVDF-HFP films exhibit antimicrobial and anti-biofilm activities against both Gram positive S. aureus and Gram negative P. aeruginosa strains. The NO-releasing PVDF-HFP polymer can also be coated on Teflon tubing to release NO under physiological conditions for extended time periods. This NO-releasing PVDF-HFP copolymer with greatly reduced chemical leaching could help enhance the biocompatibility and antimicrobial activity of various biomedical devices. STATEMENT OF SIGNIFICANCE: Fluoropolymers have been widely used in creating various biomedical implants and devices. However, nitric oxide (NO) release fluoropolymers have not been well studied to date. Additionally, in the application of biomaterials doped with NO donors, a significant amount of NO donors and their byproducts almost always leach into aqueous environment. We now report an NO releasing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fluoropolymer by incorporating a new fluorinated S-nitrosothiol. The NO release can last for 16 days under physiological conditions. The total chemical leaching was determined to be only 0.6 mol% of the initial S-nitrosothiol loaded. As expected, significant antimicrobial/anti-biofilm activities of the NO release PVDF-HFP film were observed against Gram positive S. aureus and Gram negative P. aeruginosa bacterial strains.

Poly(DL-Lactide-co-ε-Caprolactone)/Poly(Acrylic Acid) Composite Implant for Controlled Delivery of Cationic Drugs

Poly(DL-lactide-co-ε-caprolactone)/poly(acrylic acid) implantable composite reservoirs for cationic drugs are synthesized by sequentially applying photoirradiation and liquid phase inversion. The chemical composition and microstructure of reservoirs are characterized with Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and scanning electron microscopy (SEM), respectively. Drug loading and release properties are investigated using methylene blue as the drug model. Biocompatibility of reservoirs is examined through a series of in vitro tests and an in vivo experiment of subcutaneous implantation in Dark Agouti rats. Reservoirs show good ion-exchange capacity, high water content, and fast reversible swelling with retained geometry. Results of drug loading and release reveal excellent loading efficiency and diffusion-controlled release during 2 weeks. Biocompatibility tests in vitro demonstrate the lack of implant proinflammatory potential and hindered adhesion of L929 cells on the implant surface. Implants exhibit low acute toxicity and elicit a normal acute foreign body reaction that reaches the early stages of fibrous capsule formation after 7 days.

Synergistically enhanced osteoconductivity and anti-inflammation of PLGA/β-TCP/Mg(OH)2 composite for orthopedic applications

Synthetic biodegradable polymers including poly(lactide-co-glycolide) (PLGA) have been widely used as alternatives to metallic implantable materials in the orthopedic field due to their superior biocompatibility and biodegradability. However, weak mechanical properties of the biodegradable polymers and inflammatory reaction caused by the acidic degradation products have limited their biomedical applications. In this study, we have developed a PLGA composite containing beta-tricalcium phosphate (β-TCP) and magnesium hydroxide (Mg(OH)₂) as additives to improve mechanical, osteoconductivity, and anti-inflammation property of the biopolymer composite simultaneously. The β-TCP has an osteoconductive effect and the Mg(OH)₂ has a pH neutralizing effect. The PLGA/inorganic composites were uniformly blended via a twin extrusion process. The mechanical property of the PLGA/β-TCP/Mg(OH)₂ composite was improved compared to the pure PLGA. In particular, the addition of Mg(OH)₂ suppressed the inflammatory reaction of normal human osteoblast (NHOst) cells and also inhibited the differentiation of pre-osteoclastic cells into osteoclasts. Moreover, synergistically upregulated late osteogenic differentiation of NHOst cells was observed on the PLGA/β-TCP/Mg(OH)₂ composite. Taken all together, we believe that the use of β-TCP and Mg(OH)₂ as additives with synthetic biodegradable polymers has great potential by the synergistic effect in orthopedic applications.

Functionalizing PLGA and PLGA Derivatives for Drug Delivery and Tissue Regeneration Applications

Poly(lactic-co-glycolic) acid (PLGA) is one of the most versatile biomedical polymers, already approved by regulatory authorities to be used in human research and clinics. Due to its valuable characteristics, PLGA can be tailored to acquire desirable features for control bioactive payload or scaffold matrix. Moreover, its chemical modification with other polymers or bioconjugation with molecules may render PLGA with functional properties that make it the Holy Grail among the synthetic polymers to be applied in the biomedical field. In this review, the physical-chemical properties of PLGA, its synthesis, degradation, and conjugation with other polymers or molecules are revised in detail, as well as its applications in drug delivery and regeneration fields. A particular focus is given to successful examples of products already on the market or at the late stages of trials, reinforcing the potential of this polymer in the biomedical field.

Functional and Biomimetic Materials for Engineering of the Three-Dimensional Cell Microenvironment

The cell microenvironment has emerged as a key determinant of cell behavior and function in development, physiology, and pathophysiology. The extracellular matrix (ECM) within the cell microenvironment serves not only as a structural foundation for cells but also as a source of three-dimensional (3D) biochemical and biophysical cues that trigger and regulate cell behaviors. Increasing evidence suggests that the 3D character of the microenvironment is required for development of many critical cell responses observed in vivo, fueling a surge in the development of functional and biomimetic materials for engineering the 3D cell microenvironment. Progress in the design of such materials has improved control of cell behaviors in 3D and advanced the fields of tissue regeneration, in vitro tissue models, large-scale cell differentiation, immunotherapy, and gene therapy. However, the field is still in its infancy, and discoveries about the nature of cell-microenvironment interactions continue to overturn much early progress in the field. Key challenges continue to be dissecting the roles of chemistry, structure, mechanics, and electrophysiology in the cell microenvironment, and understanding and harnessing the roles of periodicity and drift in these factors. This review encapsulates where recent advances appear to leave the ever-shifting state of the art, and it highlights areas in which substantial potential and uncertainty remain.

In vitro and in vivo degradation of microfiber bioresorbable coronary scaffold

The degradation of Mirage Bioresorbable Microfiber Scaffold was evaluated in vitro and in vivo. The degradation in polymer molecular weight (MW), strut morphology, and integrity was accessed using gel permeation chromatography (GPC), X‐ray micro‐computed tomography (micro‐CT) evaluation. To simulate the physiological degradation in vitro, scaffolds were deployed in silicone mock vessels connected to a peristaltic pumping system, which pumps 37°C phosphate‐buffered saline (PBS, pH 7.4) at a constant rate. At various time points (30D, 60D, 90D, 180D, 270D, and 360D), the MW of microfibers decreased to 57.3, 49.8, 36.9, 13.9, 6.4, and 5.1% against the baseline. The in vivo degradation study was performed by implanting scaffolds in internal thoracic arteries (ITAs) of mini‐swine. At the scheduled sacrifice time points (30D, 90D, 180D, 270D, 360D, and 540D), the implanted ITAs were excised for GPC analysis; the MW of the implanted scaffolds dropped to 58.5, 34.7, 24.8, 16.1, 12.9, and 7.1, respectively. Mass loss of scaffolds reached 72.4% at 540D of implantation. Two stages of hydrolysis were observed in in vitro and in vivo degradation kinetics, and the statistical analysis suggested a positive correlation between in vivo and in vitro degradation. After 6 months of incubation in animals, significant strut degradation was seen in the micro‐CT evaluation in all sections as strut fragments and separations. The micro‐CT results further confirmed that every sample at 720D had X‐ray transmission similar to surrounding tissue, thereby indicating full degradation within 2 years. © 2017 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1842–1850, 2018.