Sustained local delivery of high-concentration vancomycin from a hybrid biodegradable, antibiotic-eluting, nanofiber-loaded endovascular prosthesis for treatment of mycotic aortic aneurysms

Prognostic factors after open and endovascular repair for infected native aneurysms of the abdominal aorta and common iliac artery

OBJECTIVE

Infected native aneurysms (INAs) of the abdominal aorta and iliac arteries are uncommon, but potentially fatal. Endovascular aneurysm repair (EVAR) has recently been introduced as a durable treatment option, with outcomes comparable to those yielded by conventional open repair. However, owing to the rarity of the disease, the strengths and limitations of each treatment remain uncertain. The present study aimed to separately assess post-open repair and post-EVAR outcomes and to clarify factors affecting the short-term and late prognosis after each treatment.

METHODS

Using a nationwide clinical registry, we investigated 600 patients treated with open repair and 226 patients treated with EVAR for INAs of the abdominal aorta and/or common iliac artery. The relationships between preoperative or operative factors and postoperative outcomes, including 90-day and 3-year mortality and persistent or recurrent aneurysm-related infection, were examined.

RESULTS

Prosthetic grafts were used in >90% of patients treated with open repair, and in situ and extra-anatomic arterial reconstruction was performed in 539 and 57 patients, respectively. Preoperative anemia and imaging findings suggestive of aneurysm-enteric fistula were independently associated with poor outcomes in terms of both 3-year mortality (hazard ratio [HR], 1.62; 95% confidence interval [CI], 1.01-2.62; P = .046, and HR, 2.24; 95% CI, 1.12-4.46; P = .022, respectively) and persistent or recurrent infection (odds ratio [OR], 2.16; 95% CI, 1.04-4.49; P = .039, and OR, 4.96; 95% CI, 1.81-13.55; P = .002, respectively) after open repair, whereas omental wrapping or packing and antibiotic impregnation of the prosthetic graft for in situ reconstruction contributed to improved 3-year survival (HR, 0.60; 95% CI, 0.39-0.92; P = .019, and HR, 0.53; 95% CI, 0.32-0.88; P = .014, respectively). Among patients treated with EVAR, abscess formation adjacent to the aneurysm was significantly associated with the occurrence of persistent or recurrent infection (OR, 2.24; 95% CI, 1.06-4.72; P = .034), whereas an elevated preoperative white blood cell count was predictive of 3-year mortality (HR, 1.77; 95% CI, 1.00-3.13; P = .048).

CONCLUSIONS

Profiles of prognostic factors differed between open repair and EVAR in the treatment of INAs of the abdominal aorta and common iliac artery. Open repair may be more suitable than EVAR for patients with concurrent abscess formation.

Chitosan/poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid) electrospun nanofibers with cephradine for superficial incisional skin wound infection management

The belated and compromised incisional skin wound healing caused by the invading of methicillin-resistance staphylococcus aureus is a serious problem in clinic. Designing a new therapeutic strategy to inhibit the growth of invading bacteria at post-surgical site might be helpful in fast healing of post-surgical wounds. In this study, we developed cephradine (Ceph) encapsulated chitosan and poly (3-hydroxy butyric acid-co-3-hydroxy valeric acid, (PHBV)) hybrid nanofibers (Ceph-CHP NFs) employing an electrospinning method to revamp the Ceph bioavailability at the post-surgical wound site to prevent the growth of invading bacteria and trigger the wound healing process. The fabricated nanofibers revealed smooth and uniform surface with a diameter range of 160 ± 25 to 190 ± 55 nm, depending on Ceph concentration. Further, the electrospun hybrid nanofibers exhibited a higher entrapment efficiency (EE) and drug loading capacity (DLC) nearly 72.8 ± 5.2 % and 16.5 ± 3.2 %, respectively. Moreover, the Ceph-CHP NFs showed high swelling rate and biodegradation in presence of lysozyme in contrast to blank CHP NFs. Ceph-CHP NFs exhibited fast drug release in initial few hours followed by slow and controlled drug release drug up to 48 h with a constant rate. In-vitro antimicrobial studies indicated the heightened efficacy of Ceph-CHP NFs against MRSA clinical isolates and exhibited no visible cytotoxicity against keratinocytes, HC11 and L929 cells. Lastly, Ceph-CHP NFs showed the enhanced wound healing and bacterial clearance from post-surgical wound compared to Ceph in C57BL/6 mice skin model. Overall, our results showed that Ceph-CHP NFs might be used as a promising wound dressing material for MRSA-infected post-surgical wounds.

Surgical Applications of Materials Engineered with Antimicrobial Properties

The infection of surgically placed implants is a problem that is both large in magnitude and that broadly affects nearly all surgical specialties. Implant-associated infections deleteriously affect patient quality-of-life and can lead to greater morbidity, mortality, and cost to the health care system. The impact of this problem has prompted extensive pre-clinical and clinical investigation into decreasing implant infection rates. More recently, antimicrobial approaches that modify or treat the implant directly have been of great interest. These approaches include antibacterial implant coatings (antifouling materials, antibiotics, metal ions, and antimicrobial peptides), antibacterial nanostructured implant surfaces, and antibiotic-releasing implants. This review provides a compendium of these approaches and the clinical applications and outcomes. In general, implant-specific modalities for reducing infections have been effective; however, most applications remain in the preclinical or early clinical stages.

A Bone-Targeting Enoxacin Delivery System to Eradicate Staphylococcus Aureus-Related Implantation Infections and Bone Loss

Post-operative infections in orthopaedic implants are severe complications that require urgent solutions. Although conventional antibiotics limit bacterial biofilm formation, they ignore the bone loss caused by osteoclast formation during post-operative orthopaedic implant-related infections. Fortunately, enoxacin exerts both antibacterial and osteoclast inhibitory effects, playing a role in limiting infection and preventing bone loss. However, enoxacin lacks specificity in bone tissue and low bioavailability-related adverse effects, which hinders translational practice. Here, we developed a nanosystem (Eno@MSN-D) based on enoxacin (Eno)-loaded mesoporous silica nanoparticles (MSN), decorated with the eight repeating sequences of aspartate (D-Asp8), and coated with polyethylene glycol The release results suggested that Eno@MSN-D exhibits a high sensitivity to acidic environment. Moreover, this Eno@MSN-D delivery nanosystem exhibited both antibacterial and anti-osteoclast properties in vitro. The cytotoxicity assay revealed no cytotoxicity at the low concentration (20 μg/ml) and Eno@MSN-D inhibited RANKL-induced osteoclast differentiation. Importantly, Eno@MSN-D allowed the targeted release of enoxacin in infected bone tissue. Bone morphometric analysis and histopathology assays demonstrated that Eno@MSN-D has antibacterial and antiosteoclastic effects in vivo, thereby preventing implant-related infections and bone loss. Overall, our study highlights the significance of novel biomaterials that offer new alternatives to treat and prevent orthopaedic Staphylococcus aureus-related implantation infections and bone loss.

Nanoparticle-Assisted Diagnosis and Treatment for Abdominal Aortic Aneurysm

An abdominal aortic aneurysm (AAA) is a localized dilatation of the aorta related to the regional weakening of the wall structure, resulting in substantial morbidity and mortality with the aortic ruptures as complications. Ruptured AAA is a dramatic catastrophe, and aortic emergencies constitute one of the leading causes of acute death in older adults. AAA management has been centered on surgical repair of larger aneurysms to mitigate the risks of rupture, and curative early diagnosis and effective pharmacological treatments for this condition are still lacking. Nanoscience provided a possibility of more targeted imaging and drug delivery system. Multifunctional nanoparticles (NPs) may be modified with ligands or biomembranes to target agents' delivery to the lesion site, thus reducing systemic toxicity. Furthermore, NPs can improve drug solubility, circulation time, bioavailability, and efficacy after systemic administration. The varied judiciously engineered nano-biomaterials can exist stably in the blood vessels for a long time without being taken up by cells. Here, in this review, we focused on the NP application in the imaging and treatment of AAA. We hope to make an overview of NP-assisted diagnoses and therapy in AAA and discussed the potential of NP-assisted treatment.

Nationwide study of surgery for primary infected abdominal aortic and common iliac artery aneurysms

BACKGROUND

Primary infected aneurysms of the abdominal aorta and iliac arteries are potentially life-threatening. However, because of the rarity of the disease, its pathogenesis and optimal treatment strategy remain poorly defined.

METHODS

A nationwide retrospective cohort study investigated patients who underwent surgical treatment for a primary infected abdominal aortic and/or common iliac artery (CIA) aneurysm between 2011 and 2017 using a Japanese clinical registry. The study evaluated the relationships between preoperative factors and postoperative outcomes including 90-day and 3-year mortality, and persistent or recurrent aneurysm-related infection. Propensity score matching was used to compare survival between patients who underwent in situ prosthetic grafting and those who had endovascular aneurysm repair (EVAR).

RESULTS

Some 862 patients were included in the analysis. Preceding infection was identified in 30.2 per cent of the patients. The median duration of postoperative follow-up was 639 days. Cumulative overall survival rates at 30 days, 90 days, 1 year, 3 years and 5 years were 94.0, 89.7, 82.6, 74.9 and 68.5 per cent respectively. Age, preoperative shock and hypoalbuminaemia were independently associated with short-term and late mortality. Compared with open repair, EVAR was more closely associated with persistent or recurrent aneurysm-related infection (odds ratio 2.76, 95 per cent c.i. 1.67 to 4.58; P < 0.001). Propensity score-matched analyses demonstrated no significant differences between EVAR and in situ graft replacement in terms of 3-year all-cause and aorta-related mortality rates (P = 0.093 and P =0.472 respectively).

CONCLUSION

In patients undergoing surgical intervention for primary infected abdominal aortic and CIA aneursyms, postoperative survival rates were encouraging. Eradication of infection following EVAR appeared less likely than with open repair, but survival rates were similar in matched patients between EVAR and in situ graft replacement.

Current approaches and future prospects of nanofibers: a special focus on antimicrobial drug delivery

Antibacterial nanofibers have a great potential for effective treatment of infections. They act as drug reservoir systems that release higher quantities of antibacterial agents/drug in a controlled manner at infection sites and prevent drug resistance, while concomitantly decreasing the systemic toxicity. With this drug delivery system, it is also possible to achieve multiple drug entrapment and also simultaneous or sequential release kinetics at the site of action. Therefore, advances in antibacterial nanofibers as drug delivery systems were overviewed within this article. Recently published data on antibacterial drug delivery was also summarised to provide a view of the current state of art in this field. Although antibacterial use seems to be limited and one can ask that 'what is left to be discovered?'; recent update literatures in this field highlighted the use of nanofibers from very different perspectives. We believe that readers will be benefiting this review for enlightening of novel ideas.

Long-term outcome of endovascular aortic repair for mycotic abdominal aortic aneurysm

BACKGROUND

This study aimed to evaluate the feasibility and efficacy of endovascular treatment for mycotic abdominal aortic aneurysm (AAA) with long-term follow-up time period.

METHODS

Patients with mycotic AAA treated with endovascular aortic repair between January 2009 and December 2017 were included in this study. The preoperative and long-term outcomes during follow-up were reviewed and analysed.

RESULTS

Sixteen patients (12 males and four females with a mean age of 57.6 ± 14.1 years) were included in this study. The technical success rate was 100%. There were no preoperative mortalities, and one instance of deep venous thrombosis during hospitalization was recorded. The median follow-up time period was 41.2 (interquartile range 24.8-69.7) months, and the late mortality rate was 12.5%. Three (18.8%) patients presented with reinfection during follow-up. One patient presented with abdominal abscess and recurrent juxtarenal aortic aneurysm at 40 months post-operatively, and he received hybrid surgery and abdominal debridement and drainage. One patient developed staphylococcal bloodstream sepsis at 3 months post-operatively and the other patient developed Salmonella bloodstream sepsis at 9 months post-operatively. Pathogenic bacteria were consistent with the previous results. They both recovered after 2 months of intravenous antibiotic treatment. At present, all three patients are still alive without endograft infection and receiving outpatient follow-up. The aneurysm diameter decreased by more than 5 mm among five patients and remained stable in 10 patients at 1 year post-operatively.

CONCLUSION

Endovascular aortic repair is a feasible and effective method of treating mycotic AAA with an acceptable reinfection rate from our single-centre experience.

Electrospun vancomycin-loaded nanofibers for management of methicillin-resistant Staphylococcus aureus-induced skin infections

Skin damage exposes the underlying layers to bacterial invasion, leading to skin and soft tissue infections. Several pathogens have developed resistance against conventional topical antimicrobial treatments and rendered them less effective. Recently, several nanomedical strategies have emerged as a potential approach to improve therapeutic outcomes of treating bacterial skin infections. In the current study, nanofibers were utilized for topical delivery of the antimicrobial drug vancomycin and evaluated as a promising tool for treatment of topical skin infections. Vancomycin-loaded nanofibers were prepared via electrospinning technique, and vancomycin-loaded nanofibers of the optimal composition exhibited nanosized uniform smooth fibers (ca. 200 nm diameter), high drug entrapment efficiency and sustained drug release patterns over 48 h. In vitro cytotoxicity assays, using several cell lines, revealed the biocompatibility of the drug-loaded nanofibers. In vitro antibacterial studies showed sustained antibacterial activity of the vancomycin-loaded nanofibers against methicillin-resistant Staphylococcus aureus (MRSA), in comparison to the free drug. The nanofibers were then tested in animal model of superficial MRSA skin infection and demonstrated a superior antibacterial efficiency, as compared to animals treated with the free vancomycin solution. Hence, nanofibers might provide an efficient nanodevice to overcome MRSA-induced skin infections and a promising topical delivery vehicle for antimicrobial drugs.

Comparative analysis and properties evaluation of gelatin microspheres crosslinked with glutaraldehyde and 3-glycidoxypropyltrimethoxysilane as drug delivery systems for the antibiotic vancomycin

In the present comparative study, gelatin microspheres (GMs) were prepared by emulsification-solvent-extraction method using well-known crosslinker: glutaraldehyde (GA) and biocompatible silane-coupling agent: glycidoxypropyltrimethoxysilane (GPTMS). Crosslinking with GA was done by a definite and common procedure, while GPTMS crosslinking potency was investigated after 5, 10, 24, and 48 h synthesis periods and the fabrication method was adjusted in order for preparation of GMs with optimized morphological and compositional characteristics. The prepared GMs were then evaluated and compared as drug delivery systems for the antibiotic vancomycin (Vm). Morphological observations, FTIR, ninhydrin assay, swelling behavior evaluation and Hydrolytic degradation analysis proved successful modification of GMs and revealed that increasing synthesis time from 5 h to 24 h and 48 h, when using GPTMS as crosslinker, led to formation of morphologically-optimized GMs with highest crosslinking degree (∼50%) and the slowest hydrolytic degradation rate. Such GMs also exhibited most sustained release period of Vm. The antibacterial test results against gram-positive bacterium Staphylococcus aureus, were in accordance with the release profiles of Vm, as well. Together, GPTMS-crosslinked GMs with their preferable characteristics and known as biocompatible gelatin-siloxane hybrids, could act as proper drug delivery systems for the sustained release of the antibiotic vancomycin.

Extended pain relief achieved by analgesic-eluting biodegradable nanofibers in the Nuss procedure: in vitro and in vivo studies

Background

The most common complaint after the Nuss procedure is severe postoperative chest pain. The aim of this study was to evaluate the effectiveness of analgesic-eluting biodegradable nanofibers in pain relief after the Nuss procedure.

Materials and methods

Poly(d,l)-lactide-co-glycolide, lidocaine, and ketorolac were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol. This solution was electrospun into a nanofibrous membrane. The elution method and high-performance chromatography were used to characterize the in vitro drug release. Stainless steel bars with and without coating of the analgesic-eluting nanofibrous membrane were implanted underneath the sternums of New Zealand white rabbits. The in vivo characteristics were further investigated.

Results

The in vitro study showed that the biodegradable nanofibers released high doses of lidocaine and ketorolac within 10 days. The in vivo study demonstrated high local and systemic concentrations of lidocaine and ketorolac. The serum creatinine level was unaffected. Animals that received implants of the analgesic-eluting nanofiber-coated stainless steel bar exhibited significantly greater food and water ingestion and physical activity than the control group did, indicating effective pain relief.

Conclusion

The proposed analgesic-eluting biodegradable nanofibers contribute to the achievement of extended pain relief after the Nuss procedure, without obvious adverse effects, in an animal model.

Nanostructure-Enabled and Macromolecule-Grafted Surfaces for Biomedical Applications

Advances in nanotechnology and nanomaterials have enabled the development of functional biomaterials with surface properties that reduce the rate of the device rejection in injectable and implantable biomaterials. In addition, the surface of biomaterials can be functionalized with macromolecules for stimuli-responsive purposes to improve the efficacy and effectiveness in drug release applications. Furthermore, macromolecule-grafted surfaces exhibit a hierarchical nanostructure that mimics nanotextured surfaces for the promotion of cellular responses in tissue engineering. Owing to these unique properties, this review focuses on the grafting of macromolecules on the surfaces of various biomaterials (e.g., films, fibers, hydrogels, and etc.) to create nanostructure-enabled and macromolecule-grafted surfaces for biomedical applications, such as thrombosis prevention and wound healing. The macromolecule-modified surfaces can be treated as a functional device that either passively inhibits adverse effects from injectable and implantable devices or actively delivers biological agents that are locally based on proper stimulation. In this review, several methods are discussed to enable the surface of biomaterials to be used for further grafting of macromolecules. In addition, we review surface-modified films (coatings) and fibers with respect to several biomedical applications. Our review provides a scientific update on the current achievements and future trends of nanostructure-enabled and macromolecule-grafted surfaces in biomedical applications.