The Influence of Solvent Processing on Polyester Bioabsorbable Polymers

Manson, Joanne; Dixon, Dorian

doi:10.1177/0885328210376997

Cited by 12 publications

(11 citation statements)

References 17 publications

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“…Explanations for the loss in film extensibility upon hydration include i) thermodynamically-driven polymer chain rearrangement to minimize contact with the infiltrating water molecules [52], and/or ii) the loss of drug and replacement of residual solvent molecules that enable high degrees of chain network mobility relative to water. Others have reported the phenomena of residual solvents altering mechanical properties in various degradable polymers [54, 55]. Regardless of the cause, the increased film stiffness may be advantageous in decreasing hyperplasia at the vein-graft anastomosis.…”

Section: Discussionmentioning

confidence: 99%

A biodegradable perivascular wrap for controlled, local and directed drug delivery

Sanders

Hogrebe

Grainger

et al. 2012

Journal of Controlled Release

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Perivascular delivery of anti-proliferative agents is an attractive approach to inhibit hyperplasia that causes stenosis of synthetic hemodialysis grafts and other vascular grafts. Perivascular drug delivery systems typically release drugs to both the vascular wall and non-target extravascular tissue. The objective of this study was to develop a biodegradable, perivascular delivery system for localized, sustained and unidirectional drug release in the context of synthetic arteriovenous (AV) grafts used for chronic hemodialysis. To this end, a dense non-porous polymer barrier layer was laminated to either i) a drug-loaded non-porous polymer layer, or ii) a porous polymer layer. To provide tuneability, the porous layer could be loaded with drug during casting or later infused with a drug-loaded hydrogel. The polymer bilayer wraps were prepared by a solvent casting, thermal-phase inversion technique using either polylactide-co-glycolide (PLGA) or polycaprolactone (PCL). Sunitinib, a multi-target receptor tyrosine kinase inhibitor, was used as a model drug. In a modified transwell chamber system, the barrier function of the non-porous PLGA backing was superior to the non-porous PCL backing although both markedly inhibited drug diffusion. As assessed by in vitro release assays, drug release duration from the drug-loaded non-porous PCL construct was almost 4-fold greater than release from the porous PCL construct infused with drug-laden hydrogel (22 days vs. 5 days); release duration from the drug-loaded non-porous PLGA construct was prolonged approximately 3-fold over release from the porous PLGA construct infused with drug-laden hydrogel (9 days vs. 3 days). Complete in vitro degradation of the PLGA porous and non-porous constructs occurred by approximately 35 days whereas the PCL constructs remained intact even after most drug was released (49 days). The PLGA non-porous bilayer wrap containing 143±5.5 mg sunitinib in the inner layer was chosen for further pharmacokinetic assessment in vivo where the construct was placed around the external jugular vein in a porcine model. At one week, no drug was detected by HPLC/MS/MS in any examined extravascular tissue whereas high levels of drug were detected in the wrapped vein segment (1048 ng/g tissue). At four weeks, drug was detected in adjacent muscle (52 ng/g tissue) but 13-fold greater amounts were detected in the wrapped vein segment (1742 ng/g tissue). These results indicate that the barrier layer effectively impedes extravascular drug loss. Tensile testing showed that the initially flexible PLGA construct stiffened with hydration, a phenomenon also observed after in vivo placement. This characteristic may be useful to resist undue circumferential venous tensile stress produced in AV grafting. The PLGA wrap bilayer formulation is a promising perivascular drug delivery design for local treatment of hemodialysis AV graft hyperplasia and possibly other hyperplastic vascular disorders.

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Section: Discussionmentioning

confidence: 99%

A biodegradable perivascular wrap for controlled, local and directed drug delivery

Sanders

Hogrebe

Grainger

et al. 2012

Journal of Controlled Release

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“…The differing polarities of the solvents affected how the polymers form upon evaporation. The evaporation rate of the solvents could also have participated in the structural variation between the films produced by the two casting methods with acetone believed to have a much quicker evaporation rate than chloroform .…”

Section: Resultsmentioning

confidence: 99%

Self‐Assembled Infrapatellar Fat‐Pad Progenitor Cells on a Poly‐ε‐Caprolactone Film For Cartilage Regeneration

2015

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Cartilage defects resulting from osteoarthritis (OA) or physical injury can severely reduce the quality of life for sufferers. Current treatment options are costly and not always effective in producing stable hyaline cartilage. Here we investigated a new treatment option that could potentially repair and regenerate damaged cartilage tissue. This novel approach involves the application of infrapatellar fat-pad derived chondroprogenitor cells onto a mechanically stable biodegradable polymer film that can be easily implanted into a defect site. Poly-ε-caprolactone (PCL) films were fabricated via solvent casting in either acetone or chloroform. The hydrophobicity, mechanical properties, and surface morphology of the films were examined. Progenitor cells from infrapatellar fat-pad were isolated, expanded, and then seeded onto the films. The cells were allowed to self-assemble on films, and these were then cultured in a chemically defined chondrogenic media for 28 days. The self-assembled tissue was characterized via histological staining, gene expression analysis, immunohistochemistry, and biochemical analysis. Chondrogenic differentiation was induced to generate a cartilaginous matrix upon the films. Despite differences between in the appearance, surface morphology, and mechanical properties of the films cast in chloroform or acetone, both methods produced tissues rich in sulfated glycosaminoglycan and collagen, although the extracellular matrix produced on chloroform-cast films appeared to contain more collagen type II and less collagen type I than acetone-cast films. These self-assembled constructs have the potential to be implanted into defect sites as a potential treatment for cartilage defect regeneration.

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“…It is becoming increasingly evident that the ideal scaffold for dental pulp tissue engineering will be injectable, not casted. This is because of the narrow spaces within the root canal and the complexity of its anatomy, particularly in the apical region so hydrogels can penetrate throughout the root canal system (14) .…”

Section: Discussionmentioning

confidence: 99%

“…Thereafter, the harvested adipose tissue was placed in a minimum essential medium (MEM) transporting media and shipped to the stem cells laboratory for processing in the same way of pulp tissue. Enzymatic digestion of tissue was done as described by Gronthos et al (14) where 3 mg/ml collagenase type I were used as digesting solution. The harvested tissues were then incubated at 37°C in a humidified atmosphere containing 5% CO 2 for the time necessary to allow cells to slip down from the explants.…”

Section: Methodsmentioning

confidence: 99%

Regenerative Potential of Simvastatin on Dental Pulp and adipose-derived stem in immature dog’s teeth: A histologic and radiographic study

2020

Al-Azhar Journal of Dental Science

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Objective: This study was directed to evaluate the regenerative potential of simvastatin (SIM) on dental pulp stem cells (DPCSs) and Adipose-derived stem cells (ASCs) in non-vital immature dogs' teeth both histologically and radiographically. Methods: The present study was carried out on 6 adult healthy male mongrel dogs aged from 4 to 6 months and their weight ranged from 12 to 17 kg. Three premolars (two rooted) in each quadrant were included in this study summing up the total number of teeth to 72. Endodontic access cavities were prepared in all experimental teeth in the buccal surface and the vital pulps of teeth were exposed till confirmation of radiolucency. Then triple antibiotic paste was used for disinfection of root canals for 3 weeks. After disinfection period, the teeth were divided into two groups: group 1; treated with dental pulp stem cells and simvastatin; while group 2was treated with adipose-derived stem cells and simvastatin. Both groups were evaluated histologically and radiographically after 1 week, 1 month and 3 months. Results: Better radiographic and histologic findings were found in the group treated with dental pulp stem cells with simvastatin than groups treated with adipose-derived stem cells and simvastatin after all evaluation periods. Conclusions: Under the condition of this study, simvastatin aids in regeneration of infected immature dog's teeth with the ability of producing functional dentin-pulp complex and inclusion of dental pulp stem cells seemed to improve the outcomes of attempted regeneration.

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The Influence of Solvent Processing on Polyester Bioabsorbable Polymers

Cited by 12 publications

References 17 publications

A biodegradable perivascular wrap for controlled, local and directed drug delivery

A biodegradable perivascular wrap for controlled, local and directed drug delivery

Self‐Assembled Infrapatellar Fat‐Pad Progenitor Cells on a Poly‐ε‐Caprolactone Film For Cartilage Regeneration

Regenerative Potential of Simvastatin on Dental Pulp and adipose-derived stem in immature dog’s teeth: A histologic and radiographic study

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