Procedural Results and One-Year Clinical Outcomes of Treatment of Bioresorbable Vascular Scaffolds Restenosis (from the RIBS VII Prospective Study).

Currently, both drug-eluting stents (DES) and drug-eluting balloons are recommended in patients with in-stent restenosis (ISR) of metallic stents. However, the clinical results of repeated interventions in patients with restenosis of bioresorbable vascular scaffolds (BVS) remain unsettled. We sought to assess the results of interventions in patients with BVS-ISR as compared with those obtained in patients with ISR of DES and bare-metal stents (BMS). Restenosis Intrastent: Treatment of Bioresorbable Vascular Scaffolds Restenosis (RIBS VII) is a prospective multicenter study (23 Spanish sites) that included 117 consecutive patients treated for BVS-ISR. Inclusion/exclusion criteria were similar to those of previous RIBS studies. Patients in the RIBS IV (DES-ISR, n = 309) and RIBS V (BMS - ISR, n = 189) randomized trials, were used as controls. Most patients with BVS-ISR were treated with DES (76%). Patients with BVS-ISR were younger, had larger vessels, and after interventions had higher in-segment residual diameter stenosis (19 ± 13%, 15 ± 11%, 15 ± 12%, p <0.001) than those treated for DES-ISR and BMS-ISR, respectively. At 1-year clinical follow-up (obtained in 100% of patients) target lesion revascularization (6%) was similar to that seen in patients with DES-ISR and BMS-ISR (8.7% and 3.7%, p = 0.32). Freedom from death, myocardial infarction, and target vessel revascularization (primary clinical end point) was 8.5%, also similar to that found in patients with DES-ISR and BMS-ISR (14.2% and 7.4%, p = 0.09). Results were also similar when only patients treated with DES in each group were compared and remained unchanged after adjusting for potential confounders in baseline characteristics. Time to BVS-ISR did not influence angiographic or clinical results. This study demonstrates the safety and efficacy of coronary interventions for patients presenting with BVS-ISR. One-year clinical results in these patients are comparable to those seen in patients with ISR of metallic stents (ClinicalTrials.gov ID:NCT03167424).

Efficacy of Biodegradable Polydioxanone and Polylactic Acid Braided Biodegradable Biliary Stents for the Management of Benign Biliary Strictures.

BACKGROUND: Benign biliary strictures (BBS) are widely treated by endoscopic procedures involving temporary stent placement. Occasionally, stents are required to be removed, making the treatment process very painful as well as expensive. Until now, no effective biodegradable biliary stents are available for clinical applications. This study aims to investigate the safety and efficacy of biodegradable polydioxanone (PDO) and polylactic acid (PLA) braided biodegradable biliary stents (BDBS) both in vitro and in vivo. METHODS: Three different diameter monofilaments of PDO (0.30, 0.35, and 0.40 mm) and PLA (0.10, 0.15, and 0.20 mm) were braided to biliary stents and their mechanical properties were studied. The stents were placed in an ex vivo bile duct model perfused with porcine bile, taken out, and observed every week until these were completely degraded. After the bile duct stenosis model was established successfully in piglet, stents with appropriate mechanical properties were further examined under endoscopy; haematology, patency time of stents, and pathological changes were observed for eight months. RESULTS: A total of 10 pigs were included (two groups; 5 PDO, 5 PLA) in the study. The patency time of the PLA group was significantly longer than that of the PDO stent group (25.7 ± 5.6w vs 11.3 ± 3.4w, respectively) in pigs. CONCLUSION: Our results prospect biodegradable PLA and PDO braided biliary stents could be a better choice to treat benign biliary strictures while degrading at different rates.

Safety of Contemporary Resorbable Fixation Systems for Craniofacial Reconstruction in Pediatric Patients.

BACKGROUND: Resorbable hardware allows adequate strength for maintaining the relative position of the craniofacial skeleton during osseous healing, and allowing subsequent growth in pediatric patients. The purpose of this study was to determine the complication profile of the latest copolymer of resorbable plates for craniofacial reconstruction in pediatric patients. METHODS: Retrospective query of the operative billing record was performed for use of the DePuy Synthes Rapidsorb Fixation System at the authors' tertiary children's hospital from 2015 to 2019. Three hundred twenty-five patients were randomly selected for analysis of complications within the first postoperative year. RESULTS: Median age at craniofacial reconstruction was 3.0 years, with 127 procedures (39.9 percent) performed for an intracranial mass and 141 procedures (44.3 percent) performed for craniosynostosis. Overall, 7.9 percent patients had a postoperative wound complication. The most common complications were dehiscence (3.8 percent), hematoma/seroma (3.5 percent), and infection (2.5 percent). There were no instances of extrusion, plate fracture, or screw loosening. Hardware complications in the temporoparietal region were more likely to occur at incision sites (p = 0.001), whereas wound complications at the frontal region were more likely to occur away from incision sites (p < 0.001). There were no differences in complications between plates secured with resorbable screws or with the resorbable injectable polymer system (p ≥ 0.161 for all). Radiotherapy was significantly implicated in development of clinical infection (p = 0.001), culture-positive infection (p < 0.001), readmission (p = 0.007), reoperation (p = 0.003), and plate removal (p = 0.007). CONCLUSION: Resorbable cranial hardware has an overall favorable complication profile for craniofacial reconstruction in pediatric patients undergoing surgical intervention for craniosynostosis or intracranial mass resection.

Therapeutic indications for sinonasal topical steroid treatment and its effects on eosinophilic chronic rhinosinusitis after endoscopic sinus surgery.

OBJECTIVE: This study evaluated the post-operative indications for sinonasal topical steroid treatment using a corticosteroid (steroid)-eluting, sinus-bioabsorbable device and its effects in patients with eosinophilic chronic rhinosinusitis. METHOD: Post-operative courses were investigated in two groups: group A with patients who underwent sinonasal topical steroid treatment, and group B with control patients who did not. RESULTS: Group A was significantly younger than group B (p < 0.01), and the pre-operative computed tomography score was significantly higher in group A than in group B (p < 0.05). In the post-operative stage, the nasal symptoms questionnaire component of olfactory loss and the post-operative endoscopic appearance score were significantly worse in group A than in group B (p < 0.01). CONCLUSION: These data suggest that younger age, more severe rhinosinusitis and post-operative olfactory loss led to the need for sinonasal topical steroid treatment to prevent relapsing inflammation after functional endoscopic sinus surgery in patients with eosinophilic chronic rhinosinusitis.

A Soft and Absorbable Temporary Epicardial Pacing Wire.

Existing temporary epicardial pacing wires (TPWs) are rigid and non-absorbable, such that they can cause severe complications after cardiac surgery. Here, a soft and absorbable temporary epicardial pacing wire (saTPW) for effectively correcting abnormal heart rates in a rabbit model, such as bradycardia and ventricular premature beat, is developed. The saTPW exhibits excellent conductivity, flexibility, cycling stability (>100 000 cycles), and less inflammatory response during two-month subcutaneous implantation in a rat model. The saTPW which consists of poly(l-lactide-co-ε-caprolactone) and liquid metal, can degrade about 13% (mass loss) in the rats over a two-month subcutaneous implantation. It can be absorbed over time in the body. The cytocompatibility and absorbability avoid secondary injuries caused by remaining wires which are permanently left in the body. The saTPW will provide a great platform for diagnosis and treatments in cardiovascular diseases by delivering the physiological signal and applying electrical stimulation for therapy.

Parametric Optimization of 3D Printed Hydrogel-Based Cardiovascular Stent.

PURPOSE: This study aimed to develop personalized biodegradable stent (BDS) for the treatment of coronary heart disease. Three-dimensional (3D) printing technique has offered easy and fast fabrication of BDS with enhanced reproducibility and efficacy. METHODS: A variety of BDS were printed with 3 types of hydrogel (~5 ml) resources (10%w/v sodium alginate (SA), 10%w/v cysteine-sodium alginate (SA-CYS), and 10%w/v cysteine-sodium alginate with 0.4%w/v PLA-nanofibers (SA-CYS-NF)) dispersed from an 22G print head nozzle attached to the BD-syringe. The printability of hydrogels into 3D structures was examined based on such variables as hydrogel's viscosity, printing distance, printing speed and the nozzle size. RESULTS: It was demonstrated that alginate composition (10%w/v) offered BDS with sufficient viscosity that defined the thickness and swelling ratio of the stent struts. The thickness of the strut was found to be 338.7 ± 29.3 µm, 262.5 ± 14.7 µm and 237.1 ± 14.7 µm for stents made of SA, SA-CYS and SA-CYS-NF, respectively. SA-CYS-NF stent displayed the highest swelling ratio of 38.8 ± 2.9% at the initial 30 min, whereas stents made of SA and SA-CYS had 23.1 ± 2.4% and 22.0 ± 2.4%, respectively. CONCLUSION: The printed stents had sufficient mechanical strength and were stable against pseudo-physiological wall shear stress. An addition of nanofibers to alginate hydrogel significantly enhanced the biodegradation rates of the stents. In vitro cell culture studies revealed that stents had no cytotoxic effects on human umbilical vein endothelial cells (HUVECs) and Raw 264.7 cells (i.e., Monocyte/macrophage-like cells), supporting that stents are biocompatible and can be explored for future clinical applications.

Pathological findings after third- and second-generation everolimus-eluting stent implantations in coronary arteries from autopsy cases and an atherosclerotic porcine model.

Pathological changes after third-generation drug-eluting stent implantation remain unclear. We compared the tissue responses of coronary arteries after the implantation of third-generation abluminal biodegradable-polymer everolimus-eluting stent (3rd EES) and second-generation durable-polymer EES (2nd EES) using autopsy specimens and an atherosclerotic porcine model. We compared the histology of stented coronary arteries obtained by autopsy performed 1-10 months after 3rd EES (n (number of cases) = 4, stent-implanted period of 3-7 months) and 2nd EES (n (number of cases) = 9, stent-implanted period of 1-10 months) implantations. The ratio of covered stent struts was higher with 3rd EESs than with 2nd EESs (3rd; 0.824 ± 0.032 vs. 2nd; 0.736 ± 0.022, p = 0.035). Low-density lipoprotein receptor knockout minipigs were stented with 3rd or 2nd EES in the coronary arteries and the stented regions were investigated. The fibrin deposition around the 2nd EES was more prominent. Additionally, higher density of smooth muscle cells was confirmed after the 3rd EES implantation. Pathological examination after the 3rd EES demonstrated a combination of less fibrin deposition and more rapid acquisition of well-developed neointima as compared to the 2nd EES at autopsy and the atherosclerotic porcine model.

A Polymer for Application as a Matrix Phase in a Concept of In Situ Curable Bioresorbable Bioactive Load-Bearing Continuous Fiber Reinforced Composite Fracture Fixation Plates.

The use of bioresorbable fracture fixation plates made of aliphatic polyesters have good potential due to good biocompatibility, reduced risk of stress-shielding, and eliminated need for plate removal. However, polyesters are ductile, and their handling properties are limited. We suggested an alternative, PLAMA (PolyLActide functionalized with diMethAcrylate), for the use as the matrix phase for the novel concept of the in situ curable bioresorbable load-bearing composite plate to reduce the limitations of conventional polyesters. The purpose was to obtain a preliminary understanding of the chemical and physical properties and the biological safety of PLAMA from the prospective of the novel concept. Modifications with different molecular masses (PLAMA-500 and PLAMA-1000) were synthesized. The efficiency of curing was assessed by the degree of convergence (DC). The mechanical properties were obtained by tensile test and thermomechanical analysis. The bioresorbability was investigated by immersion in simulated body fluid. The biocompatibility was studied in cell morphology and viability tests. PLAMA-500 showed better DC and mechanical properties, and slower bioresorbability than PLAMA-1000. Both did not prevent proliferation and normal morphological development of cells. We concluded that PLAMA-500 has potential for the use as the matrix material for bioresorbable load-bearing composite fracture fixation plates.

Tissue responses after implantation of biodegradable Mg alloys evaluated by multimodality 3D micro-bioimaging in vivo.

The local response of tissue triggered by implantation of degradable magnesium-based implant materials was investigated in vivo in a murine model. Pins (5.0 mm length by 0.5 mm diameter) made of Mg, Mg-10Gd, and Ti were implanted in the leg muscle tissue of C57Bl/6N mice (n = 6). Implantation was generally well tolerated as documented by only a mild short term increase in a multidimensional scoring index. Lack of difference between the groups indicated that the response was systemic and surgery related rather than material dependent. Longitudinal in vivo monitoring utilizing micro-computed tomography over 42 days demonstrated the highest and most heterogeneous degradation for Mg-10Gd. Elemental imaging of the explants by micro X-ray fluorescence spectrometry showed a dense calcium-phosphate-containing degradation layer. In order to monitor resulting surgery induced and/or implant material associated local cell stress, sphingomyelin based liposomes containing indocyanine green were administered. An initial increase in fluorescent signals (3-7 days after implantation) indicating cell stress at the site of the implantation was measured by in vivo fluorescent molecular tomography. The signal decreased until the 42nd day for all materials. These findings demonstrate that Mg based implants are well tolerated causing only mild and short term adverse reactions.

Long-term outcomes of Absorb bioresorbable vascular scaffold using predilation, sizing, and postdilation protocol in a real-world patient population.

OBJECTIVE: Bioresorbable vascular scaffolds (BVSs) have been a disappointment in the evolution of drug-eluting stents used in percutaneous coronary intervention because an excessive number of thrombotic complications have been reported. The aim of this study was to evaluate long-term clinical outcomes of the Absorb BVS in patients treated using a predilation, proper sizing, and post-dilation implantation technique. METHODS: The records of 110 patients who had a total of 150 Absorb BVSs implanted were retrospectively analyzed. The rate of major adverse cardiovascular events (MACEs), defined as the composite of cardiac death, target vessel myocardial infarction (MI), and target-lesion revascularization were studied using quantitative coronary angiography. RESULTS: Of the study population, 80% were male and the mean age was 60±11.3 years. The most common diagnosis was stable angina (84%). The median length of follow-up was 53 months (range: 46-59 months). The rate of predilation and postdilation was 100%, and 95%, respectively. The 4-year rate of MACEs was 20%: cardiac death in 3 patients (2.7%), target vessel MI in 9 (8.2%), and target lesion revascularization in 20 (18.2%). Definite device thrombosis occurred in 6 of 110 patients (5.5%). One case of very late scaffold thrombosis was observed at 47 months. A small BVS diameter (2.5 mm) was found to be the most powerful independent predictor of a MACE (p=0.05). CONCLUSION: The Absorb BVS was associated with an increased risk of adverse events, including late and very late device thrombosis, despite the use of a good implementation protocol.

Bioabsorbable Microplates as an External Stent for Suprastomal Collapse: A Retrospective Review.

OBJECTIVE/HYPOTHESIS: To assess the long-term decannulation outcomes of bioresorbable microplates as an external stent for pediatric tracheostomy patients with suprastomal collapse. STUDY DESIGN: Retrospective cohort study. METHODS: Hospital records of all patients who underwent a bioresorbable microplate for suprastomal collapse from 2016 to 2019 were reviewed at a single institution. The primary outcome measure was tracheostomy decannulation. RESULTS: A total of nine patients underwent placement of bioabsorbable microplates to treat suprastomal collapse. After initial tracheostomy, four patients received a laryngotracheal reconstruction prior to their external stent placement, and one patient received a mandibular distraction. The average age at the time of external stent placement was 32 (±21) months, excluding one patient who received a stent at the age of 29 years. Eight patients (88.9%) were successfully decannulated following the procedure. Decannulated patients were followed for an average of 21 (±12.5) months postoperatively, and all these patients have remained decannulated since their initial procedure. This is a total of 173 months (14.4 years) of observation postprocedure in which these patients have remained decannulated. One patient experienced postoperative crepitus requiring washout but still maintained decannulation. CONCLUSION: Bioabsorbable microplates have a reasonable chance of long-term successful decannulation when an appropriate patient is selected. Decannulation is maintained beyond the 6-month time frame in which the 85:15 poly(L-lactide-co-glycolide) polymer that comprises the external stent takes to bioabsorb. This procedure should be considered for the often difficult problem of pediatric tracheostomy with isolated suprastomal collapse. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E631-E634, 2021.

A review of preclinical absorbable inferior vena cava filters.

OBJECTIVE: Absorbable inferior vena cava filters (IVCFs) could be more effective and safer than standard IVCFs in theory, as they will self-resorb over time, thus rendering the need for filter retrieval and the risks associated with it unnecessary. This scoping review aims to evaluate the design of current absorbable IVCFs, review the development phase of the absorbable IVCFs, assess the efficacy of the absorbable IVCFs and their complications, and discuss the limitations and areas for future research. METHODS: MEDLINE, PubMed, and Embase databases were electronically searched and citations of relevant studies manually searched. Study selection and data extraction were performed by two independent reviewers using predetermined criteria and stored on premade proforma, respectively. The risk of bias (RoB) for both in vitro and in vivo studies were performed using established RoB tools. RESULTS: Eight studies were suitable for inclusion in this scoping review; five were in vivo and three were in vitro studies. No clinical trials were found. The RoB varied from moderate to high for in vivo studies and from low to moderate for in vitro studies. Overall, there was evidence from both in vivo and in vitro studies that absorbable IVCFs were effective in clot capturing and self-resorption and could decrease complications associated with standard IVCFs. However, there was a broad lack of statistical analyses and control groups to determine the significance of these findings. CONCLUSIONS: Absorbable IVCFs have shown promising features and results in preclinical models. However, significant research needs to be further performed to achieve the ideal characteristics of an absorbable IVCF before the first human trial can be conducted safely.

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.

Three-year outcomes of bioresorbable vascular scaffolds versus second-generation drug-eluting stents: Meta-analysis of randomized trials.

BACKGROUND: Bioresorbable vascular scaffolds (BVS) completely resorb within 3 years after placement into the coronary artery. The safety and effectiveness of bioabsorbable scaffolds are of critical importance during this 3-year period. OBJECTIVE: We performed a meta-analysis to compare the safety and efficacy of BVS and second-generation drug-eluting stents (DES) at 3 years after implantation. METHODS: Published randomized trials comparing BVS to second-generation DES for the treatment of coronary artery disease were identified within PubMed, EMBASE, Cochrane Library, Web of Science, and relevant Web sites with publication dates through June 2019. The primary efficacy endpoint was target lesion failure. The primary safety endpoint was definite/probable stent/scaffold thrombosis. Secondary outcomes were cardiac death, target vessel myocardial infarction, ischemia-driven target lesion revascularization, and a patient-oriented composite end point. RESULTS: Six randomized controlled trials, with a total of 5,412 patients (BVS n = 3,177; DES n = 2,235), were included. At 3 years, BVS was associated with higher rates of target lesion failure (OR = 1.33, 95%CI: 1.10-1.60, P = 0.003) and definite/probable stent/scaffold thrombosis (OR = 3.75, 95% CI: 2.22-6.35, P < .00001)compared with DES. The incidence of target vessel myocardial infarction (OR = 1.68, 95% CI: 1.30-2.17, P < .0001), ischemia-driven target lesion revascularization (OR = 1.46, 95% CI: 1.14-1.86, P = .003), and the patient-oriented composite end point(OR = 1.20, 95% CI: 1.04-1.39, P = .01) were higher for those treated with BVS compared with DES. However, there was no significant difference in risk of cardiac death (OR = 0.94, 95%CI: 0.61-1.45, P = .79) between treatment groups. CONCLUSIONS: At the 3-year follow-up, BVS was inferior to second-generation DES in both safety and efficacy.

One-year efficacy and safety of everolimus-eluting bioresorbable scaffolds in the setting of acute myocardial infarction.

BACKGROUND AND OBJECTIVES: This study sought to compare clinical outcomes between bioresorbable scaffolds (BRS) and durable polymer everolimus-eluting metallic stents (DP-EES) in patients with acute myocardial infarction (AMI) undergoing successful percutaneous coronary intervention (PCI). METHODS: From March 2016 to October 2017, 952 patients with AMI without cardiogenic shock undergoing successful PCI with BRS (n = 136) or DP-EES (n = 816) were enrolled from a multicenter, observational Korea Acute Myocardial Infarction Registry. RESULTS: In the crude population, there was no significant difference in the 1-year rate of device-oriented composite endpoint (DOCE) and device thrombosis between the BRS and DP-EES groups (2.2% vs. 4.8%, hazard ratio [HR] 0.43, 95% confidence interval [CI] 0.13-1.41, p = 0.163; 0.7% vs. 0.5%, HR 1.49, 95% CI 0.16-13.4, p = 0.719, respectively). BRS implantation was opted in younger patients (53.7 vs. 62.6 years, p < 0.001) with low-risk profiles, and intravascular image-guided PCI was more preferred in the BRS group (60.3% vs. 27.2%, p < 0.001). CONCLUSIONS: At 1-year follow-up, no differences in the rate of DOCE and device thrombosis were observed between patients with AMI treated with BRS and those treated with DP-EES. Our data suggest that imaging-guided BRS implantation in young patients with low risk profiles could be a reasonable strategy in the setting of AMI.

Foreign Body Reaction to Poly-D-L-Lactic Acid Resorbable Plates Used in Craniofacial Surgery.

Resorbable surgical materials are often used in the pediatric population to provide fixation in the growing skeleton. Although foreign body reactions to poly-D-L-lactic acid (PDLLA) plates and screws have been previously reported in other fields, to date PDLLA polymers have been well-tolerated in the setting of craniofacial surgery. The authors report a case of a previously healthy 4-month-old patient with Crouzon syndrome who underwent a frontal-orbital advancement with resorbable PDLLA plates and screws and subsequently experienced extensive foreign body reactions and wound healing complications.

The effect of calcium phosphate and silk fibroin nanofiber tuning on properties of calcium sulfate bone cements.

Calcium sulfate (CS) bone cements have been used as bone substitutes for a long time, but their clinical use is currently limited due to their rapid degradation rate and brittleness. This work aimed to study the effect of α-tricalcium phosphate (α-TCP) and silk fibroin nanofibers (SFF) on CS bone cements. The bone cements were prepared from α-CS hemihydrate (α-CSH), calcium sulfate dihydrate (CSD; as a setting accelerator) and varying α-TCP contents (0%, 5%, 10%, 15%, 20% and 25%), with SFF solution or deionized water as the solidification solution at the same liquid/solid ratio. Scanning electron microscopy, particle size distribution, x-ray diffraction and Fourier transform infrared spectroscopy were used to measure the composition and characterize the properties of the materials. The compressive strength, setting time and weight loss rate of samples were also tested. Cytotoxicity was evaluated by a Cell Counting Kit-8 assay. The results suggest that the tuning of α-TCP and SFF has an important role in determining the compressive strength and degradation rate of CS bone cements, and the properties could be changed by varying the content of α-TCP. Moreover, cell experiments showed no toxicity of the samples towards MC3T3 cells. Thus, the materials prepared from α-CSH, CSD, α-TCP and SFF in this work could provide the basis for research into CS-based bone repair materials.

Biodegradable Nanoparticles Based on Pseudo-Proteins Show Promise as Carriers for Ophthalmic Drug Delivery.

Purpose: Drug delivery to treat ocular diseases still is a challenge in ophthalmology. One way to achieve drug delivery that is investigated currently is topical administration of drug-loaded polymeric nanoparticles (NPs) that are able to penetrate ocular barriers. The purpose of this study was optimal preparation of NPs made from pseudo-proteins and evaluation of their ability to penetrate ocular tissues. Methods: Biodegradable NPs of various types were prepared by nanoprecipitation of pseudo-protein composed of l-leucine (L), 1,6-hexanediol (6), and sebacic acid (8) (8L6). Arginine-based cationic polyester amides 8R6 and comb-like polyester amide containing lateral PEG-2000 chains along with 8L6 anchoring fragments in the backbones were used to construct positively charged and PEGylated NPs. They were loaded with fluorescein diacetate (FDA) or rhodamine 6G (Rh6G) as fluorescent probes. Suspensions of the NPs were given to cultivated microglial cells and retinal pigment epithelial (RPE) cells as well as topically on eyes of C57BL/6 mice. Penetration of NPs into the eyes was checked by fluorescence analysis. Results: NPs were prepared, and their properties were characterized. Cultured microglial cells and RPE cells took up the NPs. After topical administration, penetration of NPs into the cornea of the eyes was clearly seen. Small amounts of fluorescent dyes were also found in the lens, the retina, and the sclera depending on the type of NPs. Conclusions: The results showed that the new NPs penetrate ocular tissues after topical administration and are internalized by the cells. This raises confidence that the NPs may be useful carriers of therapeutic agents for ocular delivery.