Comparative study of drug release from electrospun nanofibers loaded with clotrimazole via two different approaches using a fully automated sequential injection system

The development of new drug delivery platforms including the use of nanotechnology has been found of great interest in recent years. Two different loading approaches of the model antimycotic drug clotrimazole into the nanofibrous polycaprolactone and polydioxanone structures including electrospinning of a drug-polymer blend and impregnation of nanofibers with drug have been tested. The final amount of clotrimazole in the nanofibrous materials was determined by HPLC analysis and Raman spectroscopy. The electrospinning of blend approach allowed the adsorption of clotrimazole in a quantity of up to 30 % using mixtures with polymer/clotrimazole ratios from 2:1 to 8:1 (w/w). Ethanolic clotrimazole solutions with concentrations from 2.5 to 3.5 mg L-1 were used for adsorbing clotrimazole in blank nanofibers for 1-3 h with final clotrimazole content ranging from 3.0 to 5.7 %. Furthermore, a comparative liberation study including comparison with commercially available creams was carried out in low pressure flow system. The results obtained confirmed well controlled release of clotrimazole from both types of nanofibers. Compared to commercial pharmaceutical formulations containing 1 % clotrimazole where first-order release kinetics was observed, nanofibrous materials provided linear controlled release (zero-order kinetics) in the tested 3 h period.

Comparison of Polypropylene and Polydioxanone in the Hemitransdomal Suture: A Novel Rabbit Ear Cartilage Model

BACKGROUND

Lower lateral cartilage reshaping is one of the basic steps in rhinoplasty. Hemitransdomal suture is frequently used for dome narrowing. Different suture materials can be used for hemitransdomal suture. In this study, we investigated the effectiveness of polypropylene and polydioxanone in hemitransdomal suture by designing a new experimental model in the rabbit ear cartilage.

METHODS

Twelve young adult male New Zealand White rabbits were used. The bipedicled inverted-U-shaped cartilage was elevated in each ear of the rabbits. Two hemitransdomal sutures were applied using 5-0 polypropylene on one ear and 5-0 polydioxanone on the other ear randomly. A 5 mm high cartilage mound was created with two hemitransdomal sutures on each side. The sample size was twelve both in the polypropylene group and the polydioxanone group (n = 12). All animals were sacrificed after three months. Cartilage mound heights were measured. The samples were examined histologically regarding fibroadipose tissue, inflammation, foreign body granuloma, cartilage degeneration, and the presence of inclusion cyst.

RESULTS

Cartilage mound height was significantly higher in the polypropylene group than in the polydioxanone group at the end of the third month [3.75 mm (± 0.68) vs. 3.03 mm (± 0.69); p < 0.05]. There was no significant difference between the two groups in histological analysis (p > 0.05).

CONCLUSIONS

Polypropylene suture may be more effective in maintaining the shape given to the dome by hemitransdomal sutures in rhinoplasty. No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266.

Rate of Vaginal Cuff Dehiscence When Using Vicryl (Poliglactyn 910) Compared to PDS (Polydioxanone) for Vaginal Cuff Closure in Laparoscopic Hysterectomy

Objective: To compare the vaginal cuff dehiscence (VCD) rates using Vicryl (Poliglactyn 910) and Polydioxanone (PDS) in patients who underwent laparoscopic hysterectomy. Materials and methods: A retrospective, monocentric study was conducted, including all patients undergoing laparoscopic hysterectomy at the Department of Obstetrics and Gynaecology, Azienda di Rilievo Nazionale e di Alta Specializzazione (ARNAS) Garibaldi Nesima, Catania, between January 2014 and December 2021. Patients underwent hysterectomy for benign gynecologic pathologies (endometriosis, leiomyomas, or benign pelvic pathologies) or malignant gynecologic pathologies (endometrium cancer, complex endometrial hyperplasia, ovarian cancer, cervix cancer, or uterine carcinosarcoma). The Z-score calculation was performed to find eventual statistically significant differences between the two populations regarding VCD rates. Results: Laparoscopic vaginal cuff closure was performed, with Vicryl sutures in 202 patients and PDS sutures in 184 women. Demographic and baseline characteristics were not significantly different in the two groups. VCD occurred in three patients in the Vicryl group and did not occur in the PDS group. The three cases of VCD were precipitated by intercourses that occurred within 90 days of surgery. However, there was not a significant statistical difference between the two groups regarding VCD (p = 0.09). Conclusions: Vicryl and PDS sutures seem to be similar for vaginal cuff closure in laparoscopic hysterectomy. The VCD rate was low, and the observed differences between the Vicryl and PDS groups did not reach statistical significance. Further research through prospective studies is essential.

Biomaterials text mining: A hands-on comparative study of methods on polydioxanone biocompatibility

Scientific information extraction is fundamental for research and innovation, but is currently mostly a manual, time-consuming process. Text Mining tools (TMTs) enable automated, accurate and quick information extraction from text, but there is little precedent of their use in the biomaterials field. Here, we compare the ability of various TMTs to extract useful information from biomaterials abstracts. Focusing on the biocompatibility of polydioxanone, a biodegradable polymer for which there are relatively few scientific publications, we tested several tools ranging from machine learning approaches and statistical text analysis to MeSH indexing and domain-specific semantic tools for Named Entity Recognition. We also evaluated their output alongside a manual review of systematic reviews and meta-analyses. The findings show that TMTs can be highly efficient and powerful for mapping biomaterials texts and rapidly yield up-to-date information. Here, TMTs enable one to identify dominating themes, see the evolution of specific terms and topics, and learn about key medical applications in biomaterials literature over the years. The analysis also shows that ambiguity around biomaterials nomenclature is a significant challenge in mining biomedical literature that is yet to be tackled. This research showcases the potential value of using Natural Language Processing and domain-specific tools to extract and organize biomaterials data.

Minimally Invasive Techniques for Facial Rejuvenation Utilizing Polydioxanone Threads

Cosmetic procedures to combat the effects of aging are increasing in demand. Surgical interventions, such as rhytidectomy, have long been the standard method of providing a more youthful appearance. However, these procedures are costly, often require general anesthesia, and have potential risks such as scarring and prolonged recovery. A safe, effective, alternative to surgery is the nonsurgical thread-lift. Nevertheless, proper patient selection is critical for optimal outcomes and for patient and provider satisfaction. Over the past decade, these treatments have gained significant popularity for patients to achieve a more rejuvenated appearance with less complications and minimal downtime.

Bio-characteristics and Efficacy Analysis of Biodegradable Poly Dioxanone Dermal Filler in a Mouse Model and Humans

BACKGROUND/AIM

This research investigated the biophysical properties, safety, and efficacy of polydioxanone (PDO) filler compared to poly-L-lactic acid (PLLA), polycaprolactone (PCL), and hyaluronic acid (HA) fillers. In both mouse and human skin models, a novel collagen stimulation was compared with hyaluronic acid filler.

MATERIALS AND METHODS

An electron microscope was used to capture images of the solid particle microsphere shape. Moreover, animal models named SKH1-Hrhr were used to assess the 12-week persistence of PDO, PLLA, or PCL filler. H&E and Sirus Red staining were used to compare collagen density. Five participants in the clinical trial received three injections in the dermis over an eight-month period. Skin density, wrinkles, and gloss were evaluated using DUB® skin scanner, Antera 3D CS, Mark-Vu, and Skin gloss meter after injection to assess the efficacy of fillers.

RESULTS

PDO microspheres had uneven surfaces and were spherical and consistent in size. In comparison to other fillers, the PDO filler demonstrated complete biodegradability in just 12 weeks and better neocollagenesis, and a lower inflammatory response than the HA filler. After three injections, the human body assay showed a significant improvement in skin gloss, wrinkles, and density.

CONCLUSION

In comparison to PCL and PLLA, PDO filler demonstrated a comparable volume increase rate and better biodegradability. Furthermore, although its physical characteristics are similar to those of a solid, PDO has the advantage of being more organically spread. In photoaging mice, PDO fillers are thought to offer equivalent or superior anti-wrinkle and anti-aging effects to PBS, PCL, and PLLA.

Design and development of polydioxanone scaffolds for skin tissue engineering manufactured via green process

Fiber spinning technologies attracted a great interest since the beginning of the last century. Among these, electrospinning is a widely diffuse technique; however, it presents some drawbacks such as low fiber yield, high energy demand and the use of organic solvents. On the contrary, centrifugal spinning is a more sustainable method and allows to obtain fiber using centrifugal force and melted materials. The aim of the present work was the design and the development of polydioxanone (PDO) microfibers intended for tissue engineering, using centrifugal spinning. PDO, a bioresorbable polymer currently used for sutures, was selected as low melting polyester and DES (deep eutectic solvents), either choline chloride/citric acid (ChCl/CA) or betaine/citric acid (Bet/CA) 1:1 M ratio, were used to improve PDO spinnability. Physical mixtures of DES and PDO were prepared using different weight ratios. These were then poured into the spinneret and melted at 140 °C for 5 min. After the complete melting, the blends were spun for 1 min at 700 rpm. The fibers were characterized for physico chemical properties (morphology; dimensions; chemical structure; thermal behavior; mechanical properties). Moreover, the preclinical investigation was performed in vitro (biocompatibility, adhesion and proliferation of fibroblasts) and in vivo (murine burn/excisional model to assess safety and efficacy). The multidisciplinary approach allowed to obtain an extensive characterization to develop PDO based microfibers as medical device for implant to treat full thickness skin wounds.

Clinical features and literature review related to the material differences in thread rhinoplasty: Two case reports

BACKGROUND

Thread rhinoplasty can trigger a reaction to thread material, which is a foreign body. We compared clinical features induced by absorbable and non-absorbable threads following thread rhinoplasty.

CASE SUMMARY

Two patients who underwent different thread materials showed different clinical courses and different Hounsfield unit (HU) values in computed tomography. Patients with absorbable thread showed high HU values similar to a metallic material, and the HU value of inflammation was similar to vascular tissues with a lot of water (250). In the intraoperative field, absorbable thread materials and micro-abscesses were observed. In contrast, in the case of a non-absorbable thread, an object presumed to be thread was seen on the computed tomography (CT), and the HU value of inflammatory tissues was less than 100. In both patients, post-operative HU decreased to less than 100 and the clinical course improved. In both cases, histopathologic findings revealed foreign body granuloma associated with inflammation.

CONCLUSION

Absorbable threads were more aggressive and are more easily detected on CT.

Endoscopically Applied Biodegradable Stent in a Rabbit Model of Pediatric Tracheomalacia

OBJECTIVES

A polydioxanone (PDO) stent was developed to treat tracheomalacia in pediatric patients. However, its safety and efficacy need to be verified in animal studies before clinical trials in patients can be conducted. This study evaluated the safety and efficacy of a PDO stent in normal and tracheomalacia-model rabbits.

METHODS

In total, 29 New Zealand white rabbits were used: 13 for evaluating the biocompatibility of the PDO stent in normal rabbits and 16 for the creation of a tracheomalacia model. The tracheomalacia model was successfully established in 12 rabbits, and PDO stents were placed in eight of those rabbits.

RESULTS

The PDO stent was successfully positioned in the trachea of the normal rabbits using an endoscopic approach, and its degradation was observed 10 weeks later. The stent fragments did not induce distal airway obstruction or damage, and the mucosal changes that occurred after stent placement were reversed after degradation. The same procedure was performed on the tracheomalacia-model rabbits. The survival duration of the tracheomalacia rabbits with and without stents was 49.0±6.8 and 1.0±0.8 days, respectively. Thus, the PDO stent yielded a significant survival gain (P=0.001). In the tracheomalacia rabbits, stent degradation and granulation tissue were observed 7 weeks after placement, leading to airway collapse and death.

CONCLUSION

We successfully developed a PDO stent and an endoscopic guide placement system. The degradation time of the stent was around 10 weeks in normal rabbits, and its degradation was accelerated in the tracheomalacia model. The mucosal changes associated with PDO stent placement were reversible. Placement of the PDO stent prolonged survival in tracheomalacia-model rabbits.

In vitro evaluation of the response of human tendon-derived stromal cells to a novel electrospun suture for tendon repair

Recurrent tears after surgical tendon repair remain common. Repair failures can be partly attributed to the use of sutures not designed for the tendon cellular niche nor for the promotion of repair processes. Synthetic electrospun materials can mechanically support the tendon whilst providing topographical cues that regulate cell behaviour. Here, a novel electrospun suture made from twisted polydioxanone (PDO) polymer filaments is compared to PDS II, a clinically-used PDO suture currently utilised in tendon repair. We evaluated the ability of these sutures to support the attachment and proliferation of human tendon-derived stromal cells using PrestoBlue and Scanning Electron Microscopy. Suture surface chemistry was analysed using X-ray Photoelectron Spectroscopy. Bulk RNA-Seq interrogated the transcriptional response of primary tendon-derived stromal cells to sutures after 14 days. Electrospun suture showed increased initial cell attachment and a stronger transcriptional response compared to PDS II, with relative enrichment of pathways including mTorc1 signalling and depletion of epithelial mesenchymal transition. Neither suture induced transcriptional upregulation of inflammatory pathways compared to baseline. Twisted electrospun sutures therefore show promise in improving outcomes in surgical tendon repair by allowing increased cell attachment whilst maintaining an appropriate tissue response.

Reactivity Study of a Biodegradable Polydioxanone Tracheal Stent in a Rabbit Model

INTRODUCTION

The objective of this study was to evaluate tracheal reactivity induced by a biodegradable polydioxanone tracheal stent.

MATERIALS AND METHODS

Twenty-two rabbits were divided into 3 groups assigned to different survival times (30, 60 and 90days post-implantation). A biodegradable stent was implanted in each animal, except for 1 of each group (negative control). Implantation was performed through a small tracheotomy under fluoroscopic control. CT and histopathological studies were scheduled at the end of survival times.

RESULTS

No animal died during the procedure or follow-up. The stent had disappeared in 100% of the cases at 90days, in 50% at 60days, and in none at 30days. CT studies revealed a greater tracheal wall thickness at 30days than at 60 and 90days (1.60±0.41mm in the central part of the stent versus 1.11±0.18 and 0.94±0.11; P=.007, respectively). No granulomas were observed on histopathology. Some degree of histological changes were noted at 30days, which had reduced at 60 and 90days. Differences were also found in both CT and histology between animals in which the stent was present and animals in which it had degraded.

CONCLUSIONS

Polydioxanone stents produce a mild reaction that reverts with tracheal degradation. The use of these biodegradable stents in benign tracheal disease is promising.

Clinical Features of Skin Infection After Rhinoplasty with Only Absorbable Thread (Polydioxanone) in Oriental Traditional Medicine: A Case Series Study

BACKGROUND

Polydioxanone (PDO) is absorbable thread which is usually used for wound closure and face lifting. These days, PDO thread is used increasingly for aesthetic purposes such as correction of facial wrinkles, laxity and even rhinoplasty in many oriental traditional medicine clinics. As rhinoplasty with PDO thread increases, complications also increase. In this study, we will report on the clinical features of patients who got rhinoplasty using PDO thread.

METHODS

From August 2018 to July 2019, seven patients (three males and four females) visited our clinic for complications after rhinoplasty with PDO thread. We checked ultrasonography and laboratory findings including wound cultures. We used conservative treatment using antibiotics and performed surgery on three patients.

RESULTS

Three patients experienced severe complications with open wounds, abscesses and skin necrosis. Four patients experienced mild complications including redness and thread exposure without open wounds. The location of infection included the nasal tip and inner lining. Six patients had a history of rhinoplasty before. On ultrasonography, abscess formation was seen around the implant inserted before. During the operation, PDO thread cannot be seen except in one patient.

CONCLUSIONS

PDO thread cannot be seen in radiologic findings and can cause severe infections like abscess formation with open wounds. In severe infections, massive debridement with the removal of the implant would be required. PDO thread is absorbed usually after six months; mild infection can be controlled by the conservative treatment. The best is not undergoing rhinoplasty with PDO thread for patients who had implants because of potential side effects.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Feasibility of a polydioxanone plate as an adjuvant material in rhinoplasty in Asians

BACKGROUND

Nasal framework-supporting procedures such as septal extension grafts, derotation grafts, and columellar strut grafts are usually required in rhinoplasty in Asian patients because the skin envelope is tight, but the nasal framework is small and weak. Autologous materials are preferred, but they have some limitations related to the amount that can be harvested and the frequency of use. Therefore, synthetic materials have been used to overcome these limitations.

METHODS

A total of 114 patients who received a polydioxanone (PDS) plate as an adjuvant material in rhinoplasty from September 2016 to August 2017 were retrospectively investigated. The PDS plate was used as to support the weak framework and to correct the contour of the alar cartilages. The PDS plate was used for reinforcement of columellar struts and septal L-struts, alar cartilage push-down grafts, fixation of septal extension grafts, and correction of alar contour deformities.

RESULTS

Primary and secondary rhinoplasty was performed in 103 and 11 patients, respectively. Clinically, no significant inflammation occurred, but decreased projection of the tip was observed in seven patients and relapse of a short nose was noted in five patients.

CONCLUSIONS

PDS plates have been used in the United States and Europe for more than 10 years to provide a scaffold for the nasal framework. These plates can provide reinforcement to columellar struts, L-struts, and septal extension grafts. In addition, they can assist in deformity correction. Therefore, PDS plates can be considered a good adjuvant material for Asian patients with weak and small nasal cartilage.

Efficacy and safety of polydioxanone thread embedded at specific acupoints for non-specific chronic neck pain: a study protocol for a randomized, subject-assessor-blinded, sham-controlled pilot trial

Background

This study aims to evaluate the efficacy and safety of thread-embedding acupuncture (TEA) with polydioxanone thread embedded at various acupoints, compared with sham TEA, for the treatment of non-specific chronic neck pain.

Methods/design

This study will be an 8-week-long, two-armed, parallel, randomized, subject-assessor-blinded, sham-controlled pilot trial. Fifty eligible patients will be randomly allocated into the real TEA group or the sham TEA group. The real TEA group will receive TEA treatment at 14 fixed acupoints in the neck region. The sham TEA group will receive the same treatment as the real TEA group, but with a sham device with the thread removed. Both groups will receive treatment once a week for a total of four sessions. The primary outcome will be the mean change in the visual analog scale (VAS) from baseline to week 6 (2 weeks post intervention). Clinical relevance (ratio of the number of patients with decreases on the VAS of ≥15 mm or with percentiles ≥ 30% and ≥ 50% relative to baseline to the total number of patients), Neck Disability Index, pressure pain threshold, the Hospital Anxiety and Depression Scale, EuroQol 5-Dimensions questionnaire, Patient Global Impression of Change, blinding test, and adverse events will be used to assess secondary outcomes.

Discussion

The results of this study will provide valuable data for a large-scale clinical trial to evaluate the clinical effects of polydioxanone TEA in the treatment of patients with non-specific chronic neck pain.

Trial registration

Clinical Research Information Service (CRIS), Republic of Korea, KCT0002452. Registered on 6 September 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3058-9) contains supplementary material, which is available to authorized users.

Long-term drug delivery using implantable electrospun woven polymeric nanotextiles

A woven nanotextile implant was developed and optimized for long-term continuous drug delivery for potential oncological applications. Electrospun polydioxanone (PDS) nanoyarns, which are twisted bundles of PDS nanofibres, were loaded with paclitaxel (PTX) and woven into nanotextiles of different packing densities. A mechanistic modeling of in vitro drug release proved that a combination of diffusion and matrix degradation controlled the slow PTX-release from a nanoyarn, emphasizing the role of nanostructure in modulating release kinetics. Woven nanotextiles, through variations in its packing density and thereby architecture, demonstrated tuneable PTX-release. In vivo PTX-release, pharmacokinetics and biodistribution were evaluated in healthy BALB/c mice by suturing the nanotextile to peritoneal wall. The slow and metronomic PTX-release for 60 days from the loosely woven implant was extremely effective in enhancing its residence in peritoneum, in contrast to intraperitoneal injections. Such an implantable matrix offers a novel platform for therapy of solid tumors over prolonged durations.

Polyester Preserves the Highest Breaking Point After Prolonged Incubation in Pancreatic Juice

BACKGROUND

The impact of suture materials on the development of pancreatic fistula after pancreaticoduodenectomy remains unclear. Thus, their choice among pancreatic surgeons is still mostly experience-based. Aim of the present study is to assess what is the best suture material to be used for pancreaticojejunostomy.

MATERIALS AND METHODS

The force needed to reach the breaking point of five widely used suture materials (polypropylene, polyester, polydioxanone, silk, and polyglactin 910) has been determined through a digital precision dynamometer at baseline and after 5 and 20 days of incubation in pancreatic juice, bile, or a mixture of both.

RESULTS

Regardless of the condition, polyglactin 910 has retained only 10% of its baseline force. Silk has maintained almost 90% of its initial force showing a very low baseline value of force. In pancreatic juice, polypropylene has lost less force compared to polyester (0.25 vs. 0.93 N; p = 0.03) and polydioxanone (0.25 vs. 3.67 N; p = 0.04). Polyester and polydioxanone have showed similar values of force. However, polydioxanone has lost a significant amount of force in pancreatic juice when compared to polyester (0.93 vs. 3.67 N; p = 0.03). Polyester has showed the highest value of force needed to reach the breaking point after 20 days of incubation in pancreatic juice.

CONCLUSIONS

After incubation in pancreaticobiliary secretions, polyglactin 910 loses almost all its force. Polypropylene preserves its characteristic, but polydioxanone and polyester show absolute higher breaking points, with polyester retaining the highest value of force needed to reach its breaking point after incubation in pancreatic juice.

Sugar-cane bagasse derived cellulose enhances performance of polylactide and polydioxanone electrospun scaffold for tissue engineering

Bagasse is a waste product of sugar extraction from sugar-cane with approximately 30% cellulose content. Cellulose was successfully extracted from sugar-cane bagasse using a modified mercerization-bleaching approach with a 40% yield. Extracted cellulose was converted to cellulose acetate for enhanced electrospinnability and blended with poly-l-Lactide or polydioxanone before solution electrospinning. Physico-chemical evaluation of the electrospun mats showed variable miscibility of blends. In vitro cell studies with L929 mouse fibroblast cells was quite conclusive as regards the biocompatibility of the blended mats with proliferative behavior of cells, extracellular matrix deposition and characteristic features of healthy cellular response. MTT assay indicated that the cellulose blended mats induced higher cell densities than the controls. Cellulose content influenced parameters such as fiber diameter, porosity and cell-matrix interaction of mats impacting on cell growth and behavior. Preliminary assessment of biomineralization potential of the mats by SEM showed nano-hydroxyapatite deposits on the electrospun fibers.

Long-term results following polydioxanone sling fixation technique in unstable lateral clavicle fracture

Neer type II (Edinburgh type 3B) fractures of the lateral clavicle are unstable fractures. The optimal management of these fractures remains controversial with many surgical techniques described in the literature. Our study reports the long-term results of a modified suture (1.5-mm polydioxanone cord) and sling technique for these fractures to avoid complications associated with current techniques in the literature. Over a 5-year period, 23 patients who were (12 males, 11 females; 14 left, 9 right) with a mean age of 42 years were treated with this technique. At last follow-up, the mean Oxford score was 45.1 (range 36-48); the mean SPADI score was 7.4 (range 0-32.3); and the mean Constant score was 91.5 (range 71-100). There were one non-union and no malunion. All patients in our series, except one, returned to their pre-injury activity level. This modified suture fixation technique is safe, technically simple to perform and cheap. It achieves excellent rates of fracture union without the complications associated with other fixation methods in the literature.

Polydioxanone-based bio-materials for tissue engineering and drug/gene delivery applications

Since the commercialization of polydioxanone (PDX) as a biodegradable monofilament suture by Ethicon in 1981, the polymer has received only limited interest until recently. The limitations of polylactide-co-glycolide (PLGA) coupled with the growing need for materials with enhanced features and the advent of new fabrication techniques such as electrospinning have revived interest for PDX in medical devices, tissue engineering and drug delivery applications. Electrospun PDX mats show comparable mechanical properties as the major structural components of native vascular extracellular matrix (ECM) i.e. collagen and elastin. In addition, PDX's unique shape memory property provides rebound and kink resistance when fabricated into vascular conduits. The synthesis of methyl dioxanone (MeDX) monomer and copolymers of dioxanone (DX) and MeDX have opened up new perspectives for poly(ester-ether)s, enabling the design of the next generation of tissue engineering scaffolds for application in regenerating such tissues as arteries, peripheral nerve and bone. Tailoring of polymer properties and their formulation as nanoparticles, nanomicelles or nanofibers have brought along important developments in the area of controlled drug or gene delivery. This paper reviews the synthesis of PDX and its copolymers and provides for the first time an exhaustive account of its applications in the (bio)medical field with focus on tissue engineering and drug/gene delivery.

A layered electrospun and woven surgical scaffold to enhance endogenous tendon repair

Surgical reattachments of tendon to bone in the rotator cuff are reported to fail in around 40% of cases. There are no adequate solutions to improve tendon healing currently available. Electrospun, sub-micron materials, have been extensively studied as scaffolds for tendon repair with promising results, but are too weak to be surgically implanted or to mechanically support the healing tendon. To address this, we developed a bonding technique that enables the processing of electrospun sheets into multi-layered, robust, implantable fabrics. Here, we show a first prototype scaffold created with this method, where an electrospun sheet was reinforced with a woven layer. The resulting scaffold presents a maximum suture pull out strength of 167N, closely matched with human rotator cuff tendons, and the desired nanofibre-mediated bioactivity in vitro and in vivo. This type of scaffold has potential for broader application for augmenting other soft tissues.

Reconstruction of the orbital floor with polydioxanone: a long-term clinical survey of up to 12 years

Fractures of the orbital floor are common in injured patients, who often require operation to prevent complications and, among other materials, polydioxanone is widely used. The aim of this study was to evaluate the long-term outcomes of fractures of the orbital floor that had been reconstructed with polydioxanone foil. A total of 101 patients (73 men and 28 women) who had reconstruction of the orbital floor for defects of 2cm(2) or smaller with polydioxanone implants, over a mean (SD) time period of 8 (2) years were evaluated. Sensitivity of the infraorbital nerve, ocular motility, and diplopia were evaluated and correlated with perioperative values. Persistent hyperaesthesia was found in 15 patients, whereas in another 15 the hyperaesthesia recovered completely over time. Three patients had double vision during follow-up. Twenty patients with preoperative diplopia had no persistent double vision postoperatively, and 15 patients with disturbed ocular motility recovered completely. Two patients had persistently disturbed motility, and one patient had enophthalmos. There was a significant association between hyperaesthesia preoperatively and postoperatively (p= 0.005). In most patients reconstruction of the orbital floor with polydioxanone was successful. Long-term complications such as diplopia, compromised bulbar motility, and hyperaesthesia of the cheek were seen in a few cases, but might not have been solely related to the use of polydioxanone.

Embroidered polymer-collagen hybrid scaffold variants for ligament tissue engineering

Embroidery techniques and patterns used for scaffold production allow the adaption of biomechanical scaffold properties. The integration of collagen into embroidered polylactide-co-caprolactone [P(LA-CL)] and polydioxanone (PDS) scaffolds could stimulate neo-tissue formation by anterior cruciate ligament (ACL) cells. Therefore, the aim of this study was to test embroidered P(LA-CL) and PDS scaffolds as hybrid scaffolds in combination with collagen hydrogel, sponge or foam for ligament tissue engineering. ACL cells were cultured on embroidered P(LA-CL) and PDS scaffolds without or with collagen supplementation. Cell adherence, vitality, morphology and ECM synthesis were analyzed. Irrespective of thread size, ACL cells seeded on P(LA-CL) scaffolds without collagen adhered and spread over the threads, whereas the cells formed clusters on PDS and larger areas remained cell-free. Using the collagen hydrogel, the scaffold colonization was limited by the gel instability. The collagen sponge layers integrated into the scaffolds were hardly penetrated by the cells. Collagen foams increased scaffold colonization in P(LA-CL) but did not facilitate direct cell-thread contacts in the PDS scaffolds. The results suggest embroidered P(LA-CL) scaffolds as a more promising basis for tissue engineering an ACL substitute than PDS due to superior cell attachment. Supplementation with a collagen foam presents a promising functionalization strategy.

In vivo monitoring of structural and mechanical changes of tissue scaffolds by multi-modality imaging

Degradable tissue scaffolds are implanted to serve a mechanical role while healing processes occur and putatively assume the physiological load as the scaffold degrades. Mechanical failure during this period can be unpredictable as monitoring of structural degradation and mechanical strength changes at the implant site is not readily achieved in vivo, and non-invasively. To address this need, a multi-modality approach using ultrasound shear wave imaging (USWI) and photoacoustic imaging (PAI) for both mechanical and structural assessment in vivo was demonstrated with degradable poly(ester urethane)urea (PEUU) and polydioxanone (PDO) scaffolds. The fibrous scaffolds were fabricated with wet electrospinning, dyed with indocyanine green (ICG) for optical contrast in PAI, and implanted in the abdominal wall of 36 rats. The scaffolds were monitored monthly using USWI and PAI and were extracted at 0, 4, 8 and 12 wk for mechanical and histological assessment. The change in shear modulus of the constructs in vivo obtained by USWI correlated with the change in average Young's modulus of the constructs ex vivo obtained by compression measurements. The PEUU and PDO scaffolds exhibited distinctly different degradation rates and average PAI signal intensity. The distribution of PAI signal intensity also corresponded well to the remaining scaffolds as seen in explant histology. This evidence using a small animal abdominal wall repair model demonstrates that multi-modality imaging of USWI and PAI may allow tissue engineers to noninvasively evaluate concurrent mechanical stiffness and structural changes of tissue constructs in vivo for a variety of applications.

Evaluation of sternal closure with absorbable polydioxanone sutures in children

Introduction: Sternal dehiscence, sternal wound infection and mediastinitis are troublesome complications following median sternotomy which are major causes of morbidity and mortality of patients. Synthetic polydioxanone absorbable suture seems effective in prevention of these complications in children undergoing open heart surgery.

Methods: During 2 years period, 620 patients who underwent median sternotomy were studied. The efficacy of absorbable polydioxanone suture was tested on patients using figure-of-eight suture technique. The patients’ age ranged from newborn to 15 years old. All surgical interventions were performed according to a standard protocol.

Results: No sternal sutures were broken during the sternal closure and no case of mediastinitis was seen. Two patients experienced sternal dehiscence (0.32%). Follow-up period of patients were established between 1 to 132 months after open heart surgery.

Conclusion: Sternal closure with the polydioxanone suture in combination with figure-of-eight technique is a safe and suitable method in children with good clinical results.

Enhanced spinal fusion using a biodegradable porous mesh container in a rat posterolateral spinal fusion model

BACKGROUND CONTEXT

Posterolateral fusion (PLF) with an autogenous iliac bone graft is the most common procedure for treating various lumbar spinal diseases. However, the limited success and associated morbidity from an iliac crest graft demands new biologically competent graft enhancers or substitutes.

PURPOSE

To investigate the feasibility of tubular mesh container made of bioabsorbable sutures (poly-1,4-dioxane-2-one, PDO) for spinal fusion.

STUDY DESIGN

Experimental animal study.

METHODS

A biodegradable PDO tubular mesh container was used to contain small pieces of bone grafts. Twenty Sprague-Dawley male rats underwent PLF between L4 and L5 transverse processes with bilateral iliac grafts. Experimental animals were assigned into two different groups: autograft-only group (N=10) that underwent PLF with autograft-only or mesh container group (N=10) that underwent PLF with tubular mesh container filled with autogenous bone grafts. The rats were sacrificed at 8 weeks postoperatively, and the lumbar spines were removed. Spinal fusion was evaluated by manual palpation, microcomputed tomography, three-point bending test, and histological examination.

RESULTS

Solid fusion was achieved in all cases of the mesh container group, whereas the autograft-only group showed 60% of solid fusion. New bone mass was higher and more solidly fused in the mesh container group than the autograft-only group (p<.01). Volume of fusion mass and density of bone were significantly higher in the mesh container group (p<.05). In all cases, inflammatory response was minimal.

CONCLUSIONS

This study demonstrated that a tubular mesh container made of bioabsorbable suture is useful to hold small pieces of bone grafts and to enhance spinal fusion.

Biodegradable stent for the treatment of a colonic stricture in Crohn’s disease

Biodegradable polydioxanone stents were developed for the treatment of refractory benign esophageal strictures but have been suggested as a new therapeutic option for intestinal strictures. The primary advantage of biodegradable stents over self-expandable metallic stents is that removal is not required. There are, however, few data available on their use in the small or large bowel. We herein describe the case of a 33-year-old patient with long-standing Crohn’s disease (CD) who developed a fibrotic stricture of the sigmoid too long to be amenable to balloon dilation. The use of a biodegradable polydioxanone stent was chosen to avoid surgery. Combined endoscopic and fluoroscopic placement of the stent was technically simple, safe and clinically successful, and no recurrence of obstructive symptoms occurred during a 16-mo follow-up. Further studies are needed to evaluate the long-term efficacy and safety of biodegradable stents in the treatment of intestinal strictures, particularly in the context of CD.

Flexor tenorrhaphy using absorbable suture materials

BACKGROUND

Nonabsorbable sutures are favorable for repairing flexor tendons. However, absorbable sutures have performed favorably in an animal model.

METHODS

Two-strand sutures using the interlocking modified Kessler method with polydioxanone absorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingers from 41 consecutive patients. The medical records of average 42 follow up weeks were analyzed retrospectively. The data analyzed using the chi-squared test, and Fisher's exact test was used for postoperative complications. The results were compared with those of other studies.

RESULTS

Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and 13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in our study, there were 26 (47%) isolated flexor digitorum profundus (FDP) injuries and 29 (53%) combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted. Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers); nerve injuries occurred in 5 patients (10 fingers). Two patients had ruptures (3.6%), and one patient had two adhesions (3.6%). Using the original Strickland criteria, all the patients were assessed to be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitch granuloma were less likely occurred in our study. Compared to the Cullen's report that used nonabsorbable sutures, there was no significant difference in the rupture or adhesion rates.

CONCLUSIONS

Therefore, this study suggests that appropriate absorbable core sutures can be used safely for flexor tendon repairs.