Polyglycolic Acid Polymer Research Articles

Evaluation of polyglycolic acid as an animal-free biomaterial for three-dimensional culture of human endometrial cells.

Animal-free scaffolds have emerged as a potential foundation for consistent, chemically defined, and low-cost materials. Because of its good potential for high biocompatibility with reproductive tissues and well-characterized scaffold design, we investigated whether polyglycolic acid (PGA) could be used as an animal-free scaffold instead of natural fibrin-agarose, which has been used successfully for three-dimensional human endometrial cell culture. Isolated primary endometrial cells was cultured on fibrin-agarose and PGA polymers and evaluated various design parameters, such as scaffold porosity and mean fiber diameter. Cytotoxicity, scanning electron microscopy (SEM), and immunostaining experiments were conducted to examine cell activity on fabricated scaffolds. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and SEM results showed that endometrial cells grew and proliferated on both scaffolds. Immunostaining showed cytokeratin and vimentin expression in seeded cells after 7 days of culture. On both scaffolds, an epithelial arrangement of cultured cells was found on the top layer and stromal arrangement matrix on the bottom layer of the scaffolds. Therefore, fibrin-agarose and PGA scaffolds successfully mimicked the human endometrium in a way suitable for in vitro analysis. Both fibrin-agarose and PGA scaffolds could be used to simulate endometrial structures. However, because of environmental and ethical concerns and the low cost of synthetic polymers, we recommend using PGA as a synthetic polymer for scaffolding in research instead of natural biomaterials.

The use of a polyglycolic acid polymer graft in Peyronie's disease - preliminary outcomes.

Plaque incision and grafting is indicated for patients with Peyronie's Disease [PD] and severe curvature, complex deformities or for patients with significant penile shortening. To date, no graft studied has been considered ideal. The aim of this study is to conduct a descriptive analysis about functional results with the use of a bioabsorbable graft for PD treatment. A single-center, retrospective evaluation of a cohort of patients who were treated by plaque incision and grafting with a polyglycolic acid polymer graft (Gore® Bio-A®) between 2018 and 2021 was conducted. Correction of penile curvature was the main outcome. Loss of penile sensitivity, de novo erectile dysfunction and any other adverse event were the secondary endpoints. 14 patients were included in this study (mean age 59.5 ± 7.2 years). The median follow-up time was 12 months (range 3-12). The curvature correction rate was 78.5%. Glans hypoesthesia was present in one of 14 patients (7.1%) and refractory erectile dysfunction was reported in 64.2%. None of the patients presented any major adverse event based on Clavien-Dindo classification. Curvature correction and changes in penile sensitivity rates were similar to those found in the literature. No major surgical complications, such as graft rejection, infection, and extrusion, occurred in this sample. Although a population with a higher prevalence of erectile dysfunction was included in this sample, higher rates of refractory erectile dysfunction were observed and these findings should be confirmed in further studies.

Tenogenesis of Decellularized Porcine Achilles Tendon Matrix Reseeded with Human Tenocytes in the Nude Mice Xenograft Model.

Cultivation of autologous human tenocytes in a cell-free xenogenic extracellular tendon matrix (xECM) could present an approach for tendon reconstruction. The aim of this study was to achieve tendon-like tissue formation by implanting decellularized porcine Achilles tendons recellularized with human hamstring tendon-derived tenocytes into nude mice. The structure of decellularized xECM was histologically monitored before being dynamically reseeded with human tenocytes. After 6–12 weeks in vivo, construct quality was monitored using macroscopical and histological scoring systems, vitality assay and quantitative DNA and glycosaminoglycan (GAG) assays. For comparison to tendon xECM, a synthetic polyglycolic acid (PGA) polymer was implanted in a similar manner. Despite decellularized xECM lost some GAGs and structure, it could be recellularized in vitro with human tenocytes, but the cell distribution remained inhomogeneous, with accumulations at the margins of the constructs. In vivo, the xECM constructs revealed in contrast to the PGA no altered size, no inflammation and encapsulation and a more homogeneous cell distribution. xECM reseeded with tenocytes showed superior histological quality than cell-free implanted constructs and contained surviving human cells. Their DNA content after six and 12 weeks in vivo resembled that of native tendon and xECM recellularized in vitro. Results suggest that reseeded decellularized xECM formed a tendon-like tissue in vivo.

Synthesis of poly(glycolic acids) via solution polycondensation and investigation of their thermal degradation behaviors

Polyglycolic acid (PGA) was successfully synthesized via solution and melt/solid polycondensations. PGA was synthesized by solution polymerization under vacuum by using diphenylsulfone as solvent and methanesulfonic acid as catalyst and the inherent viscosity of resultant PGA was 0.2 dl/g. The intrinsic viscosity was obtained up to 0.35 dl/g of the PGA synthesized by melt/solid polycondensation. Whereas, PGA synthesized by longer hours of SSP was insoluble in most of the known solvents, which might have higher molecular weight as well as crystallinity. Crystallographic structure of PGA was confirmed by XRD and the resulting PGA polymer was similar in thermal degradation to that of commercially available polyglycolide (Kuredux), synthesized by ring opening polymerization. Both PGAs were characterized for thermal decomposition kinetic studies using thermaogravimetric analysis (TGA), to investigate the effect of end-group and molecular weight on thermal degradation behavior. TGA was performed at 6 different heating rates from 5 to 50 °C/min and data was analyzed by three different approaches to obtain activation energy. Activation energy from Kissinger’s approach was 112 kJ/mol for lab synthesized PGA and 119 kJ/mol for Kuredux, whereas from Flynn and Wall’s method, it was observed as 115 kJ/mol and 121 kJ/mol for solution-polymerized PGA and Kuredux respectively and activation energies calculated from dynamic experiment method was also comparable of both PGAs. From dynamic experiment method linearity curve starts as low as 1 % decomposition and continues as high as 97 % with decomposition temperature ranges 219 to 380 °C for PGA and 230 to 406 °C for Kuredux. Consequently, Kissinger’s method, Flynn and Walls method and the dynamic experiment method reveal that the thermal decomposition behavior of polyglycolic acids and polyglycolide is similar, regardless of end groups and synthetic routes which is supposed to be random chain cession.

Hydrolytic Degradation and Morphological Characterization of Electrospun Poly(glycolic acid) [PGA] Thin Films of Different Molecular Weights Containing TiO2 Nanoparticles

Thin films of polyglycolic acid (PGA), a biodegradable and biocompatible polymer, were prepared by electrospinning and were studied according to their molecular weights. TiO2 nanoparticles were also used as additives at concentrations of 2–8 wt%. The films were morphologically characterized and exhibited a homogeneous distribution of TiO2 with only slight differences depending on the molecular weight. In particular, fibers with low-molecular-weight PGA were thinner and had an average diameter of 77 nm. Furthermore, they showed a higher resolution of the TiO2 crystal planes regardless of the crystal habit involved. During the melting of the PGA fibers, one single and prominent melting endotherm was observed, which was independent of molecular weight, TiO2 content, and crystal phase involved. This was in contrast to quiescent PGA crystallization and melting, during which the typical double melting behavior was present. After thermal measurements, TiO2 did not show characteristics of a nucleating agent for the PGA fibers. However, it acted as a degradation retardant for low-molecular-weight PGA. Because of its hygroscopicity, anatase, a material with the ability to absorb water, was a more efficient hydrolytic degrader than rutile.

Tissue Engineered Airways: A Prospects Article.

An ideal tracheal scaffold must withstand luminal collapse yet be flexible, have a sufficient degree of porosity to permit vascular and cellular ingrowth, but also be airtight and must facilitate growth of functional airway epithelium to avoid infection and aid in mucocilliary clearance. Finally, the scaffold must also be biocompatible to avoid implant rejection. Over the last 40 years, efforts to design and manufacture the airway have been undertaken worldwide but success has been limited and far apart. As a result, tracheal resection with primary repair remains the Gold Standard of care for patients presenting with airway disorders and malignancies. However, the maximum resectable length of the trachea is restricted to 30% of the total length in children or 50% in adults. Attempts to provide autologous grafts for human application have also been disappointing for a host of different reasons, including lack of implant integration, insufficient donor organs, and poor mechanical strength resulting in an unmet clinical need. The two main approaches researchers have taken to address this issue have been the development of synthetic scaffolds and the use of decellularized organs. To date, a number of different decellularization techniques and a variety of materials, including polyglycolic acid (PGA) and nanocomposite polymers have been explored. The findings thus far have shown great promise, however, there remain a significant number of caveats accompanying each approach. That being said, the possibilities presented by these two approaches could be combined to produce a highly successful, clinically viable hybrid scaffold. This article aims to highlight advances in airway tissue engineering and provide an overview of areas to explore and utilize in accomplishing the aim of developing an ideal tracheal prosthesis. J. Cell. Biochem. 117: 1497-1505, 2016. © 2016 Wiley Periodicals, Inc.

Electrospun biodegradable nanofibers scaffolds for bone tissue engineering

ABSTRACTMany polymeric materials have been developed and introduced for bone regeneration. Especially, their nanofibrous forms are mostly applied for artificial extracellular matrices. Polymeric materials in their nanofibrous form show some potent properties such as high surface‐to‐volume ratio, tunable porosity, and ease of surface functionalization. Benefiting from the properties of their main polymer and additives, they can provide new opportunities for cell seeding, proliferation, and new 3D‐tissue formation. This article focuses on most cited polymeric nanofibrous scaffolds fabricated by electrospinning and recent achievements. They were divided into two main categories: natural (collagen, silk, keratin, gelatin, chitosan, and alginate) and synthetic (e.g., polycaprolactone, polylactic acid, and polyglycolic acid) polymers. The role of several additives like hydroxyapatite, bone morphogenetic proteins (BMPs), tricalcium phosphate, and collagen type I in improving the adhesion, differentiation, and tissue formation of stem cells were discussed. Finally, the osteogenic capacity and ability of nanofibrous scaffolds to support the growth of clinically relevant bone tissue were briefly studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 42883.

Development and evaluation of a new biodegradable vena cava filter in a canine model

Preliminary testing of a new biodegradable inferior vena cava filter in a canine model. The biodegradable filter consisted of two parts, a filter cone and a stent. The filter cone was constructed of six polyglycolic acid polymer strands anchored to a handmade absorbable stent. Central inferior vena cava fixation was accomplished by the absorbable stent, which was made of polycaprolactone. Device insertion was performed through a 9F sheath under ultrasound guidance on 10 adult beagles. The filters were operatively retrieved at 6 weeks after implantation. The inferior venae cavae were subsequently analyzed grossly and using light microscopy. None of the 10 beagles had abnormal vital signs. All of the 10 filters migrated cephalad approximately <2cm and remained below the renal vein ostia. One specimen had evidence of incorporated residual strands within the caval wall on gross examination. The caval wall became thickened at the level of filter placement without significant lumen narrowing. There was no evidence of pulmonary embolism caused by degradation products of the absorbable strands. Biodegradable inferior vena cava filters are feasible and potentially could be used in specific patients who are at temporary high risk of venous thromboembolism.

The effect of mechanical extension stimulation combined with epithelial cell sorting on outcomes of implanted tissue-engineered muscular urethras

Urethral defects are common and frequent disorders and are difficult to treat. Simple natural or synthetic materials do not provide a satisfactory curative solution for long urethral defects, and urethroplasty with large areas of autologous tissues is limited and might interfere with wound healing. In this study, adipose-derived stem cells were used. These cells can be derived from a wide range of sources, have extensive expansion capability, and were combined with oral mucosal epithelial cells to solve the problem of finding seeding cell sources for producing the tissue-engineered urethras. We also used the synthetic biodegradable polymer poly-glycolic acid (PGA) as a scaffold material to overcome issues such as potential pathogen infections derived from natural materials (such as de-vascular stents or animal-derived collagen) and differing diameters. Furthermore, we used a bioreactor to construct a tissue-engineered epithelial–muscular lumen with a double-layer structure (the epithelial lining and the muscle layer). Through these steps, we used an epithelial–muscular lumen built in vitro to repair defects in a canine urethral defect model (1 cm). Canine urethral reconstruction was successfully achieved based on image analysis and histological techniques at different time points. This study provides a basis for the clinical application of tissue engineering of an epithelial–muscular lumen.

Evaluation of six synthetic surgical meshes implanted subcutaneously in a rat model

The long-term efficacy and mechanical integrity of implanted materials is largely determined by early host response. Therefore, implanting materials with well-characterized tissue responses provides the greatest chance of 'one-hit' surgical successes, without repeated interventions to replace, repair or remove non-compliant biomaterials. Six synthetic meshes were implanted subcutaneously in a rat model to deduce and quantify modulations in host response, based on material fabrication variables. The materials consisted of knitting variations of polypropylene (PP), polyethyleneterephthalate (PET) and polyglycolic acid (PGA) yarns and were implanted for 2, 5, 7, 14 and 28 days before fixation and both semi- and fully quantitative histopathology. In a subcutaneous niche, material weight did not influence foreign body response. PET stimulated earlier inflammation than PP and PGA, which normalized over 28 days. Multifilament meshes recruited foreign body giant cells, which were largely absent from monofilaments. Using CD68, PGA was demonstrated to be the greatest leukocyte-activating polymer at a number of the time points analysed. This research therefore highlights that underlying polymer composition may be more over-arching in deciding the inflammatory properties of surgical meshes, based on increased macrophagic responses to PGA vs alternative base polymers of comparable weights and porosities. Copyright © 2013 John Wiley & Sons, Ltd.

Pathophysiological evaluation of cerecyte coil embolization for experimental broad neck aneurysms.

Cerecyte second-generation coils feature inner surfaces coated with an absorbable polyglycolic acid (PGA) polymer. Their use is expected to accelerate aneurysm organization, but time course data are limited. The present experimental study was therefore conducted to clarify the processes by pathological examination. Methods. Two types of experimental aneurysms were initially generated in adult mongrel dogs, one bifurcation and another of lateral wall type. Long-term persistence of each was defined by follow-up angiography for more than 1 year. Embolization of the aneurysms was then performed using only cerecyte coils, and follow-up angiography was conducted after 2 and 4 weeks followed by pathological examination. Results. Organization of both types of broad neck aneurysm was apparent 4 weeks after embolization, which is earlier as compared with already reported data for bare coils.

Resorbable Inferior Vena Cava Filters: Trial in an In-vivo Porcine Model

Purpose To determine the feasibility, effects, and complications of a resorbable inferior vena cava (IVC) filter in a porcine model. Materials and Methods Ten handmade, dual-filtration level, resorbable IVC filters were produced and gas sterilized. A dual-filtration cone was constructed using polyglycolic acid polymer strands oriented in a staggered cone formation with the apex of the cone in a cephalad orientation in relation to the IVC. IVC fixation was accomplished using a nitinol Z-stent, which was not resorbable. Operative insertion employing a paramedian incision, infrarenal vena caval dissection, venotomy, and device insertion using an 8-F rigid sheath was performed on 10 Yorkshire-type pigs (> 50 lb). Percutaneous delivery was not performed because of cost constraints. The IVC filters were operatively removed en bloc 6 weeks after implantation, and the pigs were euthanized. The IVC specimens were subsequently analyzed grossly and using light microscopy. Results In 9 (90%) of the 10 retrieved devices, the filtration cones were completely dissolved. One device (10%) had a retained strand of filtration cone material completely incorporated into the caval wall, excluded from luminal flow. Significant inflammatory response was appreciated from the specimen histology, and significant collagen deposition was observed, especially on trichrome staining. The intima and media of 9 of 10 specimens were two to three times normal thickness. Significant reactive change was also appreciated in the pericaval lymph nodes that were taken in the specimen. One pig (10%) developed a postoperative wound infection requiring treatment. Conclusions Resorbable IVC filters are feasible and could be used for specific patient populations. This study outlines the need for further research of bioabsorbable polymers, absorption mechanics in the vascular system, absorption times, efficacy models, and practical application.

Autogenous bone graft combined with polylactic polyglycolic acid polymer for treatment of dehiscence around immediate dental implants

The use of composite bone grafts in dehiscence defects around immediate dental implants are aimed at improving the outcome of the regenerative process. The present study was designed to evaluate the efficacy of combinations of autogenous bone graft with a synthetic copolymer polylactic and polyglycolic acid (Fisiograft) on bone healing of buccal dehiscence defects around immediate dental implants. Sixteen adult male patients who each received an immediate implant for a single tooth replacement at a maxillary anterior or premolar site were included in this study. Patients were divided into 2 groups. One group received immediate dental implants augmented with autogenous bone graft combined with Fisiograft. The other group received immediate dental implants augmented with autogenous bone graft alone. The results revealed that both treatment modalities led to significant improvements for the primary outcome regarding bone fill as well as a significant reduction of probing pocket depth and gain of attachment level. Moreover, there were slightly statistically significant differences between the groups. In conclusion, the combination of autogenous bone graft and Fisiograft showed a slight superiority to autogenous bone graft alone, suggesting that it could be an optimum bone substitute for treatment of dehiscence around immediate dental implant.

O.601 Ultrasound examination in thyrolingual duct cysts diagnostic

The historical development of polyglycolic acid (PGA) and polylactic acid (PLA) polymers and copolymers for use in surgery is set down. Details of the synthesis of PGA and PLA polymers from their cyclic diesters are described, as well as a series of glycolide/lactide copolymers. The reactions were followed by time sampling techniques. The resulting samples were characterized by gel permeation chromatography (g.p.c.), differential scanning calorimetry (d.s.c.), thermogravimetric analysis (t.g.a.) and 220 MHz proton nuclear magnetic resonance spectroscopy (n.m.r.). Details of these analytical technicques are given. The respective reactivity ratios of glycolide and lactide are elucidated. The effect of 60Co γ radiation on the molecular properties of PGA is also shown.

O.603 A new method of resorbable osteosynthesis in craniosynostos

The historical development of polyglycolic acid (PGA) and polylactic acid (PLA) polymers and copolymers for use in surgery is set down. Details of the synthesis of PGA and PLA polymers from their cyclic diesters are described, as well as a series of glycolide/lactide copolymers. The reactions were followed by time sampling techniques. The resulting samples were characterized by gel permeation chromatography (g.p.c.), differential scanning calorimetry (d.s.c.), thermogravimetric analysis (t.g.a.) and 220 MHz proton nuclear magnetic resonance spectroscopy (n.m.r.). Details of these analytical technicques are given. The respective reactivity ratios of glycolide and lactide are elucidated. The effect of 60Co γ radiation on the molecular properties of PGA is also shown.

Local and Systemic Effects of a Tissue Engineered Neobladder in a Canine Cystoplasty Model

Tissue engineered bladders are emerging as a potential treatment option in urological surgery. Although successful neobladders can be engineered with autologous cells on a biodegradable polymer scaffold, studies of the local and systemic effects on host tissue have not been extensively pursued. We examined such effects at predetermined time points after implantation of tissue engineered neobladders in a canine cystoplasty model. Eight dogs underwent trigone sparing cystectomies. Six dogs (experimental group) received bladder augmentation with tissue engineered constructs produced from autologous urothelial and smooth muscle cells on a prefabricated polyglycolic acid polymer scaffold. Two beagles (control group) received bladder augmentation with the polyglycolic acid scaffold alone. Serial urodynamic studies, cystograms, peripheral blood smears, urinalysis, serum chemistry, complete blood count and electrolytes were done at predetermined time points postoperatively. The bladder, and local and distant organs were retrieved 6 months after surgery for analysis. Capacity and compliance of the engineered bladders reached normal levels by 6 months. Engineered bladders showed tissue composition similar to that of normal bladders. Infiltration of inflammatory cells was minimal and subsided with time. An increase in the total systemic leukocyte count and in bacteriuria was evident initially at 1 week but they returned to normal levels by 1 month postoperatively. Other systemic parameters remained within normal levels at all time points. There was no evidence of abnormal findings in local or distant organs. Implantation of polymer molds seeded with autologous bladder cells did not show significant local or systemic toxicity in a canine model. This study suggests that such engineered neobladders are safe and effective for reconstructive surgery.

Distant migration of a bioabsorbable implant in the shoulder

Metal implants about the shoulder have been recognized to be associated with serious complications since the publication of Zuckerman and Matsen. 14 Zuckerman J.D. Matsen F.A. Complications about the glenohumeral joint related to the use of screws and staples. J Bone Joint Surg. 1984; 66A: 175 Google Scholar Rockwood et al 10 Neer C.S. Rockwood Jr, C.A. Fractures and dislocations of the shoulder. in: Rockwood Jr, C.A. Green D.P. Fractures in adults. Lippencott, Philadelphia1984: 908-909 Google Scholar reported several cases of metal implant migrating at a distance from the shoulder, some with catastrophic and even fatal consequence. 13 Wirth M.A. Rockwood C.A. Migrations of a broken cerclage wire from the shoulder girdle into the heart: a case report. J Shoulder Elbow Surg. 2000; 9: 543 Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar Bioabsorbable implants were devised in part to mitigate these complications. These implants also offered the option of easier postoperative MRI imaging, and were purported to make revision surgery, should it be required, easier. Initial α polyester formulations using polyglycolic acid polymers resorbed fairly quickly. This created problems when longer fixation times were required. The relatively rapid hydrolysis of these implants also created a significant load of bioabsorption debris, resulting in reports of significant synovitis, local reaction, and even giant cell-like responses. 2 Berg E.E. Oglesby J.W. Loosening of a biodegradable shoulder staple. J Shoulder Elbow Surg. 1996; 5: 76-78 Abstract Full Text PDF PubMed Scopus (15) Google Scholar , 3 Burkart A. Imhoff A.B. Roscher E. Foreign-body reaction to the bioabsorbable Suretac device. Arthroscopy. 2000; 16: 91-95 Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar , 4 Cheng J.C. Wolf E.M. Chapman J.E. Johnston J.O. Pigmented villonodular synovitis of the shoulder after anterior capsulolabral reconstruction. Arthroscopy. 1997; 13: 257-261 Abstract Full Text PDF PubMed Scopus (15) Google Scholar , 6 Edwards D.J. Hoy G. Saies A.D. Adverse reaction to an absorbable shoulder fixation device. J Shoulder Elbow Surg. 1994; 3: 230-233 Abstract Full Text PDF PubMed Scopus (116) Google Scholar Implants with longer absorption times, involving different combinations of α polyesters were substituted. These implants have longer mechanical integrity, but the extended lifespan of these implants increases the risk of damage to the soft tissues if they become loose or break. Freehill et al 8 Freehill M.Q. Harms D.J. Huber S.M. Atlihan D. Buss D.D. Poly-L-lactic acid tack synovitis after arthroscopic stabilization of the shoulder. Am J Sports Med. 2003; 31: 643-647 PubMed Google Scholar reported a 20% incidence of chondral injuries with the use of bioabsorbable tacks in the shoulder, and other authors 12 Warner J.J.P. Miller M.D. Marks P. Fu F.H. Arthroscopic Bankart repair with the Suretac device Part I. Clinical observations. Arthroscopy. 1995; 11: 2-13 Abstract Full Text PDF PubMed Scopus (89) Google Scholar note a 10% incidence of tack synovitis. The time to complete hydrolysis of these implant in vivo is unknown; adverse reactions to these materials have occurred as late as 143 weeks after implantation. 5 Ciccone II, W.J. Motz C. Bentley C. Tasto J.P. Bioabsorbable implants in orthopaedics: new developments and clinical applications. J Am Acad Orthop Surg. 2001; 9: 280-288 Crossref PubMed Scopus (137) Google Scholar Anecdotal reports of bioabsorbable interference screws in the knee 13 Wirth M.A. Rockwood C.A. Migrations of a broken cerclage wire from the shoulder girdle into the heart: a case report. J Shoulder Elbow Surg. 2000; 9: 543 Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar suggest a considerably longer duration of time prior to hydrolysis, further increasing the risk of complication related to loose or migrated implants. Many of these reports suggest that the risk of local injury with loose bioabsorbable implants approaches the risk of loose metal implants. This is of special concern, as these implants are invisible on plain radiographs and require magnetic resonance imaging (MRI) scanning to image the implant postoperatively. Extra-articular migration outside the shoulder of a bioabsorbable implant, however, has not been reported. We report a case of migration of a bioabsorbable shoulder implant outside the shoulder girdle requiring late open removal.

A study on the rate of degradation of the bioabsorbable polymer polyglycolic acid (PGA)

As part of a study to characterise bioabsorbable scaffolds for tissue engineering an investigation has been conducted into the rate of degradation of polyglycolic acid (PGA). This is one of the most commonly used bioabsorbable materials and has been used in sutures since the 60s and more recently in cell scaffolds, drug delivery devices and bone fixation pins. This study looks at the influence that surface-to-volume ratio i.e. thickness of material, has on degradation. By degrading various thicknesses of PGA in a buffer saline solution over 24 days and testing their properties at regular intervals, a knowledge of how surface-to-volume ratio affects degradation was developed. Properties such as weight loss, crystallinity, molecular weight and structural integrity were measured. Results showed that rate of mass loss was dependent on sample thickness but crystallinity, melting point and molecular weight were independent of thickness.

Bladder autoaugmentation using various biodegradable scaffolds seeded with autologous smooth muscle cells in a rabbit model

Background/Purpose The prolapsed mucosa after bladder autoaugmentation usually collapses, and the volume increment is limited. This study is aimed at evaluating the efficacy of autoaugmentation assisted with 2 different scaffolds, polyglycolic acid (PGA) mesh and small intestinal submucosa (SIS), seeded with autologous bladder smooth muscle cells in a rabbit model. Methods One month after an initial 70% partial cystectomy, various autoaugmentation surgeries were performed. These procedures included traditional autoaugmentation (n = 6) and traditional autoaugmentation covered with PGA or SIS without cell seeding (N) (PGA-N, n = 6; SIS-N, n = 6) or covered with scaffolds seeded with autologous bladder smooth muscle cells (C) (PGA-C, n = 6; SIS-C, n = 6). All were followed up by bladder volume measurement and retrieved on 1, 2, 3, and 6 months. Statistical analysis was by analysis of variance. Results A normal urothelial layer was maintained in all groups. Only PGA-C group showed a significant bladder capacity increment as compared with the other groups in all time-points ( P = .001, .000, .000, and .001 at first, second, third, and sixth months, respectively). The PGA-C group showed grossly normal bladder wall with scattered smooth muscle bundles. The other groups had marked graft shrinkage with only unorganized muscle fibers. Conclusion Cell-seeded PGA polymer facilitates smooth muscle regeneration, offers sufficient bladder wall backup, and achieves satisfactory volume increment after the autoaugmentation with time. The collagen matrix, although seeded with cells, did not offer adequate mechanical support after the surgery.

PH-compensation effect of bioactive inorganic fillers on the degradation of PLGA

It has been suggested that acidic degradation product of the poly (α-hydroxy acids) results in pH decrease in the vicinity of the scaffolds, which may be responsible for biocompatibility concerns rose recently about polylactide acid (PLA), polyglycolic acid (PGA) polymers and their copolymer poly (lactic acid-co glycolic acid) (PLGA). This in vitro study was performed to evaluate the pH-compensation ability of bioactive inorganic fillers (BIFs) such as wollastonite (W), bioglass 45S5 (BG 45S5) and hydroxyapatite (HA) on the acidic degradation products of PLGA. Three composite scaffolds of PLGA incorporated with BIFs were fabricated and immersed in phosphate buffered saline (PBS, pH 7.4) solution at 37 °C for 8 weeks to evaluate the pH changes of the PBS, the mass loss and water absorption of the scaffolds, and the molecular weight loss of the PLGA in the scaffolds. The results indicated that the pH of the PLGA group fell to a value of 4.3 in 8 weeks while the pH of the composite groups containing W and BG 45S5 was maintained between 7.7–7.3 and 8.15–7.1 throughout the soaking period, respectively. However, the pH of the composite group containing HA exhibited an almost linear decrease from 7.4 to 5.6 at an average rate of 0.05 per day. In addition, the incorporation of W and BG delayed the degradation of the PLGA in the composites while the incorporation of HA accelerated the degradation. Furthermore, the W and BG in the composite scaffolds accelerated weight loss of the scaffolds and increased their capacity to absorb water during the initial incubation period. All of these results suggested that incorporations of both W and BG 45S5 into PLGA strongly affected the degradation behavior of scaffolds and were effective in compensation of the pH decrease caused by the acidic degradation products of the PLGA.