Bioresorbable Polymer Research Articles

Surface nanostructuring of bioresorbable implants to induce osteogenic differentiation of human mesenchymal stromal cells

Surface nanostructuring of bioresorbable polymers is a promising solution for tissue regeneration therapies, as such nanostructured implants non-toxically degrade after producing localized and prolonged stimuli. In this work, a process chain for the fabrication of bioresorbable polymer implants was developed and validated. The implants present surface arrays of nanopillars whose main design parameters were optimized to induce the osteogenic differentiation of human stem cells. In vitro and in vivo cell experiments provided evidence for the potential application in tissue regeneration and revealed that nanopillars' diameter, height, and spacing need to be independently optimized to effectively promote osteogenic differentiation.

Initial Experience With a Bioresorbable Polymer Anchor.

BackgroundAnchors are frequently used in reconstructive orthopedic surgery to achieve fixation of soft tissue to bone. Anchors vary with respect to material composition, configuration, and methods of fixation at the site of attachment. The fixation component of anchoring devices has generally evolved from metal-fabricated implants to various types of bioresorbable anchors. The SonicAnchorTM (Stryker, Kalamazoo, MI USA) polymer implant provides a unique form of anchor fixation using SonicFusionTM technology to achieve interdigitation within cancellous bone while being radiolucent and providing a small footprint.MethodsDuring a four-year period, 116 patients underwent a reconstructive orthopedic foot and ankle surgical procedure with the use of at least one bioresorbable polymer anchor (SonicAnchor implant). There were 59 males and 57 females, with an average age of 42 years (range: 12-83 years).ResultsA total of 233 bioresorbable anchor (SonicAnchor) implants were used in 116 patients. Of the 116 patients, 108 (93.1%) achieved successful clinical healing of their surgery at their most recent follow-up. The average follow-up duration was 309 days (range: 14-1,429 days). Eight (6.9%) patients were lost to follow-up prior to clinical healing. Two (1.7%) patients underwent reoperation. Also, 65 (56%) patients had at least six months of follow-up and 36 (31%) had at least one year of follow-up.ConclusionsThis preliminary clinical trial of patients undergoing soft tissue repair or reconstruction with a bioresorbable polymer appears to perform comparably to other commercially available devices. The lack of adverse events, mechanical failures, or infections further supports the safety of this device.

1-Year Safety of 3-Month Dual Antiplatelet Therapy Followed by Aspirin or P2Y12 Receptor Inhibitor Monotherapy Using a Bioabsorbable Polymer Sirolimus-Eluting Stent.

This study evaluated the safety of 3-month dual antiplatelet therapy (DAPT) after implantation of a bioresorbable polymer sirolimus-eluting stent (BP-SES) and compared P2Y12inhibitor with aspirin monotherapy 3 months after DAPT. Patients who underwent percutaneous coronary intervention using BP-SES were enrolled and followed for 1 year. Patients with a history of stent thrombosis were excluded. The primary endpoint was a composite of all-cause death, myocardial infarction, stroke (ischemic and hemorrhagic), definite or probable stent thrombosis, and severe bleeding at 12 months. The BP-SES arm of the CENTURY II trial was used as a conventional DAPT group for comparison. After DAPT, patients were maintained on either aspirin (n=846) or a P2Y12inhibitor (n=674 patients).In all, 1,695 patients were enrolled in the study across 65 centers. The primary endpoint occurred in 4.3% of patients at 1 year. After propensity score adjustment, the incidence of the primary endpoint was not inferior in those receiving DAPT for 3 months compared with conventional DAPT (5.5%; Pnon-inferiority<0.0001). The incidence of the primary endpoint and severe bleeding did not differ between the aspirin and P2Y12inhibitor monotherapy groups. After adjustment, 3-month DAPT was not inferior to longer DAPT after BP-SES implantation in terms of net adverse clinical events. There was no difference in bleeding and thrombotic events between P2Y12inhibitor and aspirin monotherapy after 3 months DAPT.

Cardiovascular outcomes associated with Ultrathin bioresorbable polymer sirolimus eluting stents versus thin, durable polymer everolimus eluting stents following percutaneous coronary intervention in patients with type 2 diabetes mellitus: A meta-analysis of published studies.

Background:Percutaneous coronary intervention with the new generation drug eluting stents (DES) is 1 among the revascularization procedures required to treat patients with coronary artery disease (CAD). Since late stent thrombosis and silent myocardial infarction are highly associated with type 2 diabetes mellitus (T2DM), an analysis comparing the newer generation DES in this specific subgroup of patients would be scientifically relevant.In this analysis, we aimed to systematically compare the cardiovascular outcomes observed with the ultrathin bioresorbable polymer sirolimus eluting stents (SES) versus thin, durable polymer everolimus eluting stents (EES) following percutaneous coronary intervention in patients with T2DM.Methods:Through online databases, relevant studies comparing ultrathin bioresorbable polymer SES versus the durable polymer EES were carefully searched. The cardiovascular outcomes were assessed during a follow-up time period of 1 year and more than 1 year (1–5 years) respectively. This meta-analysis was carried out by the latest version of the RevMan software. Following analysis, the results were represented by odds ratios (OR) with 95% confidence intervals (CI).Results:A total number of 1967 patients with T2DM were included in this analysis. During a 1 year follow-up time period, target lesion failure (TLF) (OR: 0.59, 95% CI: 0.34–1.02; P = .06, target vessel revascularization (TVR) (OR: 0.97, 95% CI: 0.55–1.70; P = .91) and target lesion revascularization (TLR) (OR: 0.91, 95% CI: 0.44–1.87; P = .79) were similarly observed with ultrathin bioresorbable polymer SES versus the thin, durable polymer EES in these patients with T2DM. Other cardiovascular outcomes including myocardial infarction (MI), major adverse cardiac events, all-cause mortality (OR: 0.72, 95% CI: 0.37–1.40; P = .34), cardiac death and stent thrombosis (OR: 0.85, 95% CI: 0.45–1.62; P = .63) were also similarly observed with these 2 types of new stents. During a follow-up time period above 1 year (1–5 years), still no significant difference was observed in TLF, TVR, TLR, major adverse cardiac events, MI, all-cause mortality, cardiac death and stent thrombosis (OR: 0.62, 95% CI: 0.33–1.16; P = .14).Conclusions:The ultrathin bioresorbable polymer SES were similar to the durable polymer EES in these patients with T2DM. These 2 types of new generation stents were comparable in terms of cardiovascular outcomes. Hence, they might be recommended in patients with T2DM. Upcoming trials should be able to confirm this hypothesis.

The state-of-the-art coronary stent with crystallized sirolimus: the MiStent technology and its clinical program.

Drug-eluting stents (DES) have been developed over recent decades and the implantation of DES is the standard of care in contemporary percutaneous coronary intervention for patients with coronary artery disease. The MiStent sirolimus-eluting stenthas several unique features; ultra-thin (64μm) struts, a bioresorbable polymer and a controlled drug release from microcrystalline sirolimus as a reservoir embedded in the vessel wall. Results of recent clinical trials demonstrated the potential performance of this state-of-the-art DES. In the present review, we provide an overview of the development of DES, in particular the design and performance of the novel MiStent sirolimus-eluting stent from technological and clinical points of view and discuss the potentials of this new type of DES.

Development of Components of Prolonged Action Antibacterial Dosage Forms Using SCF Technologies

Gentamicin and levofloxacin are encapsulated into bioresorbable polymer scaffolds and microparticles by the SCF methods: particles from gas saturated solutions (PGSS) and plasticization, with the subsequent foaming of amorphous polymers using supercritical carbon dioxide. The kinetics of the release of the incorporated drug substances into model physiological media are studied. It is shown that the use of the developed methods of SCF-encapsulation of drugs in bioresorbable carriers allows varying the size, shape, and morphology of the formed structures and, accordingly, the rate of release of the drugs into the physiological environments. In our opinion, this approach can be very promising for the development of components of new highly effective antibacterial prolonged action dosage forms.

Stretchable, dynamic covalent polymers for soft, long-lived bioresorbable electronic stimulators designed to facilitate neuromuscular regeneration

Bioresorbable electronic stimulators are of rapidly growing interest as unusual therapeutic platforms, i.e., bioelectronic medicines, for treating disease states, accelerating wound healing processes and eliminating infections. Here, we present advanced materials that support operation in these systems over clinically relevant timeframes, ultimately bioresorbing harmlessly to benign products without residues, to eliminate the need for surgical extraction. Our findings overcome key challenges of bioresorbable electronic devices by realizing lifetimes that match clinical needs. The devices exploit a bioresorbable dynamic covalent polymer that facilitates tight bonding to itself and other surfaces, as a soft, elastic substrate and encapsulation coating for wireless electronic components. We describe the underlying features and chemical design considerations for this polymer, and the biocompatibility of its constituent materials. In devices with optimized, wireless designs, these polymers enable stable, long-lived operation as distal stimulators in a rat model of peripheral nerve injuries, thereby demonstrating the potential of programmable long-term electrical stimulation for maintaining muscle receptivity and enhancing functional recovery.

Transcatheter-Delivered Expandable Bioresorbable Polymeric Graft With Stenting Capacity Induces Vascular Regeneration

As the next step in the translation of vascular tissue engineering, this study uniquely combines transcatheter delivery and in situ tissue regeneration using a novel bioresorbable electrospun polymer graft that can be implanted minimally invasively. Once delivered inside a small-diameter vessel, the electrospun microstructure supports the vessel wall, facilitates cellular infiltration, and guides organized tissue formation.

Clinical practice and outcomes in elderly STEMI patients undergoing PCI with new generation DES – data from a large worldwide registry

Abstract Background The best treatment option for elderly patients with acute myocardial infarction (MI) remains unclear. Purpose We aimed to determine clinical practice and outcomes of PCI with a new generation DES in patients with ST-elevated MI (STEMI), aged ≥80 years included in a one of the largest real-world PCI registries. Methods e-Ultimaster is a prospective, world-wide, multi-centre registry that enrolled 36,671 patients with coronary artery disease, treated with a thin strut sirolimus-eluting stent with abluminal bioresorbable polymer coating, across 50 countries. 34,538 patients who completed 1-year follow-up or who died were included in the analysis. The primary endpoint was 1-year target lesion failure (TLF: cardiac death, target vessel (TV) MI, clinically driven (CD) target lesion revascularization (TLR)). An Clinical Event Committee adjudicated all endpoint-related adverse events. Results 6863 presented with STEMI at baseline (19.9%). Mean age of STEMI patients was 61.0±11.7 years, with 78.8% males. Diabetes was present in 20.9% and hypertension in 52.4%. Of 6863 STEMI patients, 430 patients (6.2%) were aged ≥80 years, with 46.5% females compared to 19.5% females in the younger group. Patients in the older group had more comorbidities (hypertension and renal impairment) and more often took oral anticoagulant medication (9.2% vs 3.9%; p&amp;lt;0.001). At discharge 94.9% of older STEMI patients were on dual antiplatelet therapy (DAPT) as compared to 97.6% of younger STEMI patients (p=0.002). Older STEMI patients more often took clopidogrel as second antiplatelet agent (54.7% vs 39.8%; p&amp;lt;0.001) and were less often on prasurgrel (2.3%vs 10.9%; p&amp;lt;0.001) and ticagrelor (41.2% vs 48.1%; p=0.005). STEMI patients in the older group more often had multivessel disease (52.1 vs 45.8%; p=0.01), treatment of the left main artery (4.7 vs 1.4%; p&amp;lt;0.001) and more calcified lesions (18.8 vs 11.2%; p&amp;lt;0.001). Other lesion characteristics were similar between the two groups. Preferred access approach was radial and was alike in the two groups (87.0 vs 84.0%; p=0.10) In-hospital mortality was more frequent in older STEMI patients (2.3% vs 0.8%; p=0.003). More bleedings were observed in older vs younger STEMI patients at discharge. One-year TLF was significantly higher in older age group (7.0% vs 3.0%; p&amp;lt;0.01), mainly driven by increased rates of cardiac death. All-cause mortality and bleedings were also more frequent in older STEMI patients. No differences were observed in revascularization or ST rates (1.4 vs 1.1%; p=0.48). Conclusions In elderly patients with STEMI, in-hospital mortality rates as well as bleeding rates were higher as compared to younger patients, while 1-year rates of revascularization and ST did not differ between the groups. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Terumo Europe

One year clinical outcomes of contemporary PCI in patients with chronic coronary syndrome: experience from large scale e-ULTIMASTER registry

Abstract Background The 2019 ESC guideline on chronic coronary syndromes (CCS) provided insights on the management of patients with stable angina. Purpose To explore one-year outcomes of CCS patients undergoing percutaneous revascularisation representing daily clinical practice. Methods We investigated CCS patients enrolled in e-Ultimaster registry (NCT02188355), which is a prospective, multicentre, worldwide, all-comers registry enrolled &amp;gt;36, 000 patients treated with a thin strut (80μm) bioresorbable polymer sirolimus-eluting stents (Ultimaster). The primary endpoint was target lesion failure (TLF) at 1 year (defined as a composite of cardiac death, target-vessel related myocardial infarction (TV-MI) and clinically-driven target lesion revascularization (CD-TLR). An independent Clinical Event Committee adjudicated all end-point related events. Results Our analysis included in total 15540 patients presented with stable angina (n=12300, 79.2%) or silent ischemia (n=3240, 20.9%) at enrolment. The mean age of CCS patients was 65.7±10.5 years and 76.1% were male. Regarding comorbidities, 69.9% of CCS patient were hypertensive, 30.9% had diabetes, 62.2% had high cholesterol, and 7.5% had renal impairment. The percentage of current smokers was 15.7%. Among CCS patients, 28.1% reported previous MI while 35.2% had history of PCI and 7.4% of CABG. Among CCS patients, 42.4% were diagnosed with multivessel disease. The average number of lesions identified per patient was 1.8±1.0, and the number of treated lesions was 1.5±0.8. The left main artery was treated in 4.1% of CCS patients, 8.1% for chronic total occlusion, 6.1% for instent restenosis, while 14% of the patients were treated in one or more bifurcation lesions. Approximately 80% of the procedures were preformed via radial access. The rate of TLF at one year was 2.9%, with 0.95% of cardiac death, 0.8% of TV-MI and 1.5% of CD-TLR. Definite or probable stent thrombosis (ST) rate was 0.42%, and any bleeding occurred in 1.8% of the patients. 71.3% of the patients were already on dual antiplatelet therapy (DAPT) before procedure, 93.3% were on DAPT at 3 months follow up, while DAPT was continued in 64.9% of patients at 1 year. At 3 months after index PCI, 91.4% of the treated CCS patients were angina free, 7.6% reported stable angina, and 0.5% unstable angina. The similar result was observed at 1 year, with 90.9% of the patients remaining angina free, 7.5% of patients with stable angina, while only 0.6% reported unstable angina. In a stepwise regression model, we identified risk factors of TLF in CCS patients including age, body mass index, diabetes, renal failure, lesion complexity such as target vessel LM or bifurcation, and number of stents implanted. Conclusions In this large, international all-comers registry, more than 90% of CCS patients treated with PCI remain angina free at one year, with low rate of TLF and ST, adding further evidence to ongoing debate about CCS treatment strategy. Funding Acknowledgement Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Limted study funding by Terumo

Nanostructured scaffolds based on bioresorbable polymers and graphene oxide induce the aligned migration and accelerate the neuronal differentiation of neural stem cells

Within the field of neural tissue engineering, there is a huge need for the development of materials that promote the adhesion, aligned migration and differentiation of stem cells into neuronal and supportive glial cells. In this study, we have fabricated bioresorbable elastomeric scaffolds combining an ordered nanopatterned topography together with a surface functionalization with graphene oxide (GO) in mild conditions. These scaffolds allowed the attachment of murine neural stem cells (NSCs) without the need of any further coating of its surface with extracellular matrix adhesion proteins. The NSCs were able to give rise to both immature neurons and supporting glial cells over the nanostructured scaffolds in vitro, promoting their aligned migration in cell clusters following the nanostructured grooves. This system has the potential to reestablish spatially oriented neural precursor cell connectivity, constituting a promising tool for future cellular therapy including nerve tissue regeneration.

The Cone Flare Crush Modified-T (CFCT) stenting technique for coronary artery bifurcation lesions.

BackgroundThe present study is a prospective observational single arm clinical investigation, with parallel bench test interrogation, aimed at investigating the technical feasibility, safety and clinical outcomes with the cone flare crush modified-T (CFCT) bifurcation stenting technique. Bifurcation percutaneous coronary intervention (PCI) remains an area of ongoing procedural evolution. More widely applicable and reproducible techniques are required.MethodsFrom April 2018 until March 2019, 20 consecutive patients underwent bifurcation PCI using the CFCT technique with a Pt-Cr everolimus drug-eluting stent with a bioresorbable polymer. Exercise stress echocardiography was performed at 12-month follow-up. The primary outcome was a composite of cardiac related mortality, myocardial infarction, target lesion/vessel revascularization and stroke. Safety secondary endpoints included bleeding, all-cause mortality and stent thrombosis.ResultsAll patients underwent a successful CFCT bifurcation procedure with no complications to 30-day follow-up. One patient met the primary endpoint requiring target lesion revascularization at 9 months for stable angina. There were no other primary or secondary outcome events in the cohort. There were no strokes, deaths, stent thrombosis or myocardial infarction during the follow-up period. The mean CCS score improved from 2.25 to 0.25 (p < 0.0001). Optical coherence tomography (OCT) and bench test findings indicated optimal side branch ostial coverage and minimal redundant strut material crowding the neo-carina.ConclusionsThe CFCT technique appears to be a safe, efficacious and feasible strategy for managing coronary artery bifurcation disease. Expanded and randomized datasets with longer term follow-up are required to further explore confirm this feasibility data. (ANZCTR ID: ACTRN12618001145291).

Heart valves from polymeric fibers: potential and limits.

Transcatheter aortic valve implantation (TAVI) has become today a popular alternative technique to surgical valve replacement for critical patients. However, with only six years follow-up on average, little is known about the long-term durability of transcatheter implanted biological tissue. Moreover, the high cost of biological tissue harvesting and chemical treatment procedures favor the development of alternative synthetic valve leaflet materials. In that context, thin, flexible and porous textile constructions could be considered as interesting candidates. However, these constructions must be strong enough to withstand the load applied on the leaflet especially in aortic position. Moreover, the interaction of textile material with living tissue should be comparable to biological valve tissue, and the foreign body reaction (FBR) as well as the calcification mechanisms should be controlled. In the frame of heart valve tissue engineering strategies, the use of bioresorbable polymer scaffolds is expected to limit that FBR. However, to precisely control the degradation of the polymer is not trivial. Conversely, when permanent textile polymers are considered, the porosity of the fibrous scaffold tends to induce exaggerated tissue ingrowth which may prevent the implants from remaining flexible. In that context, the ideal synthetic fibrous valve leaflet remains to be found. The purpose of this study was to investigate the possible strategies which have been adopted over the last 50 years regarding the use of textile as heart valve leaflet material. Results showed that textile presented potential, despite remaining strong challenges. It came out that hybrid textiles combining bioresorbable and permanent polymer fibers arranged in both non-woven and woven or knitted way could probably help providing strength and generating appropriate tissue ingrowth.

A comparison of the increased temperature accelerated degradation of Poly(d,l-lactide-co-glycolide) and Poly(l-lactide-co-glycolide)

Bioresorbable polymers composed of Poly(lactide), Poly(glycolide) and their related copolymers have become increasingly popular for the preparation of bone substitute constructs. In vitro tests assessing the degradative changes in physicochemical, mechanical, and biological properties of bioresorbable polymers are generally carried out at 37 °C, in pH 7.4 phosphate-buffered saline (PBS). However, long degradation times, varying from months to years make it difficult to assess these polymers at their late stages of degradation. An increased temperature accelerated degradation methodology, that simulates the long-term degradation of Poly(d,l-lactide-co-glycolide) and Poly(l-lactide-co-glycolide), has been validated in this study. Samples were degraded in PBS, under sterile conditions. Degradation temperatures of 47 °C, 57 °C and 70 °C were selected and compared to physiological temperature, 37 °C. At predetermined time intervals, samples were retrieved and evaluated for changes in mass, swelling, molecular weight, crystallinity, and thermal properties. The results from this study suggest that the degradation mechanism at elevated temperatures is similar to that observed at 37 °C. It is recommended that 47 °C is adopted by the research community to accelerate the degradation of these polymers. It is hoped the application of this methodology could be used as a valuable tool, prior to the assessment of the long-term biocompatibility of these polymers.

Advancing Toward 3D Printing of Bioresorbable Shape Memory Polymer Stents.

Stents have evolved significantly since their introduction to the medical field in the early 1980s, becoming widely used in percutaneous coronary interventions and following nephrological procedures. However, the current commercially available stents do not degrade and remain in the body forever, leading to problems like restenosis in cardiovascular applications or requiring removal procedures in ureteral applications. Efforts to replace metal with resorbable materials have largely been halted after the commercial failure of and safety concerns elicited by Abbott's Absorb stent in 2017. Industry continues to use common polymers such as poly(l-lactide) (PLLA) and polycaprolactone (PCL) for biomedical products, but due to the weak mechanical properties of these bioresorbable materials in comparison to metals, these devices have struggled to accomplish the goals set, increasing risk of thrombosis. 3D printing stents using bioresorbable and shape memory materials could provide a method of patient-personalized production, remove the need for balloon expansion, and limit stent migration, thus bringing a new age of stent technology. The investigation of a range of 3D-printable and bioresorbable shape-memory polymers can provide solutions to the shortcomings of previously explored bioresorbable stents and revitalize the medical device industry efforts into advancing stent technology.

Bioresorbable and degradable behaviors of PGA: Current state and future prospects

AbstractPolyglycolic acid (PGA) is a class of semicrystalline, bioresorbable polymers that have been widely used in a number of applications. No other bioresorbable materials can fully replace PGA in tissue engineering. Understanding degradation mechanisms in PGA is important for improving the efficiency and effectiveness in various fields including implantation. This review begins with a discussion on terminology of polymer degradation and hydrolytic degradation mechanism with a delineative model. This review also focus on previous degradation studies taking advantage of its fast‐degrading behavior and the mechanism behind hexafluoroisopropanol (HFIP) being the sole solvent for PGA. Finally, the merits of PGA are discussed with many potential future applications along with their associated challenges.

Individual patient data analysis of the BIOFLOW study program comparing safety and efficacy of a bioresorbable polymer sirolimus eluting stent to a durable polymer everolimus eluting stent.

ObjectivesThis analysis of pooled individual patient data (IPD) aimed to evaluate the safety and efficacy of a bioresorbable polymer sirolimus eluting stent system (BP‐SES; Orsiro) compared to a durable polymer everolimus eluting stent system (DP‐EES; Xience) in the pooled population as well as in subgroups.MethodsIPD with up to 12 months follow‐up of the randomized controlled trials BIOFLOW‐II (NCT01356888), ‐IV (NCT01939249), and ‐V (NCT02389946) as well as the all comers registry BIOFLOW‐III (NCT01553526) were pooled. A total of 3,717 subjects (2,923 in BP‐SES and 794 in DP‐EES) with 5,328 lesions (4,225 lesions in BP‐SES and 1,103 in DP‐EES) were included in the IPD. The primary endpoint was target lesion failure (TLF) at 12 months follow‐up. Subgroups analyzed included diabetes, age (≥65 years), gender, complex lesions (B2/C), small vessels (reference vessel diameter ≤2.75 mm), multivessel treatment, renal disease, and patients with acute coronary syndrome.ResultsOverall, TLF at 12 months was significantly lower with 5.2%in the BP‐SES group versus 7.6% in the DP‐EES group (p = .0098). Similarly, target vessel myocardial infarction (TV‐MI) was 3.1 versus 5.7% (p = .0005). The rate of stent thrombosis was similar in both groups (0.004%). By regression analysis, an independent stent effect in favor of BP‐SES was observed for TLF (p = .0043) and TV‐MI (p = .0364) in small vessels.ConclusionResults of this IPD analysis suggest that the BP‐SES with ultrathin struts is as safe as and more efficacious than DP‐EES in the overall cohort and especially in small vessels.

Encapsulation of octenidine hydrochloride into bioresorbable polyesters for extended antimicrobial activity

Nosocomial infections remain a serious threat even for patients of highly industrialized countries. These infections occur on surgical sites and wounds, on catheter entry sites, tubes and other indwelling devices. Medical devices providing local antiseptic action over an extended time period represent an opportunity to prevent such infections. One way to achieve this goal is the encapsulation of active molecules into bioresorbable polymer microparticles, which can locally release the compound of interest along a tunable time span depending on the polymer characteristic. In this work, spray drying is used to encapsulate the broad band antiseptic octenidine hydrochloride into a set of poly(d,l-lactide) (PDLLA) and poly(d,l-lactide-co-glycolide) (PLGA) carrier materials with different molecular weights and chain end-groups, forming redispersable powders. It is demonstrated that the carrier materials bearing acid end-groups provide a significantly larger entrapment efficacy comparing with their ester counterparts independently of carrier composition and molecular weight. The quantitative understanding of the release mechanism allows guiding the selection of suitable encapsulating polyesters to tune initial burst and long time release of a given drug. Finally, it is demonstrated on cultures of Staphylococcus epidermidis that the encapsulated and subsequently released OHC has conserved its antiseptic activity, which supports the potential applicability of the approach.

Bioresorbable magnesium-reinforced PLA membrane for guided bone/tissue regeneration

Considering the inferior mechanical properties of the current bioresorbable polymers, a novel bioresorbable magnesium-reinforced polylactide (PLA) membrane was designed for the application in critical defect sites in guided bone/tissue regeneration. The PLA-FAZ91 membrane was fabricated by combining two PLA membranes with a fluoride-coated AZ91 (9 wt% Al, 1 wt% Zn) (FAZ91) magnesium alloy core by hot pressing. A combined double-layered PLA membrane was used as the control group. A three-point bending test was performed to compare their maximum load and stiffness. Samples were immersed in the HBSS for 20 weeks, and their weight loss percentages were recorded, and a three-point bending test was performed after immersion. An ion release test was performed by immersing samples in the HBSS for 4 weeks and determining the pH and ion concentrations of the HBSS. Cell viability was tested by culturing pre-osteoblast cells with sample extracts in the culture medium obtained from degraded samples. As a result, PLA-FAZ91 showed a significantly higher maximum load and stiffness than those of the non-reinforced PLA membrane. The weight loss of PLA-FAZ91 was much faster, as FAZ91 showed major degradation and was completely degraded after 16–20 weeks of immersion. The degradation of the PLA wrap was accelerated by FAZ91. The mechanical superiority of PLA-FAZ91 over PLA endured for at least 3 weeks during immersion. The pH, magnesium- and fluoride-ion concentration in the PLA-FAZ91 group increased at an appropriate rate. The cell viability was not adversely affected by the addition of FAZ91 to PLA. Therefore, the bioresorbable magnesium-reinforced PLA membrane has the potential to be used as a good alternative to pure PLA membrane in guided bone/tissue regeneration.

Stent strut thickness and acute vessel injury during percutaneous coronary interventions: an optical coherence tomography randomized clinical trial.

Compare the degree of acute vascular injury caused by a polymer-free, thin-strut drug-eluting stent (DES) to that caused by a bioresorbable polymer, thick-strut DES using optical coherence tomography (OCT). Fifty patients requiring nonurgent PCI were randomized to receive either a thin or a thick-strut DES. OCT was performed before and after stent implantation. OCT-based injury score (IS) after implantation was numerically higher within thick-strut stents 0.32 vs. 0.23, but the difference was NS (P = 0.61). Edge dissections were present in 36% of the patients without differences between groups. Tissue prolapse (TP) area was larger with thin-strut stents (2.26 vs. 1.83 mm2, P = 0.04). Stent expansion and symmetry index were similar between the two platforms (85% vs. 94%, P = 0.08; and 0.82 vs. 0.80, P = 0.25). No differences were observed in total malapposition area (1.85 mm2 in thin-strut stents vs. 1.47 mm2, P = 0.48). Regarding the influence of plaque-type, IS tended to be higher (non-significant) with thick strut DES in fibrocalcific plaques. Stent malapposition area was smaller in fibrous plaques, especially with thin strut stents (P = 0.03). There was no difference in the extent of OCT-based vessel injury associated with thin and thick-strut DES platforms. TP was larger with the thin strut DES, potentially reflecting a deeper stent embedment in the vessel wall.