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Tracheal stenosis is commonly caused by injury, resulting in inflammation and fibrosis. Inhibiting inflammation and promoting epithelization can reduce recurrence after initial successful treatment of tracheal stenosis. Steroids play an important role in tracheal stenosis management. This study in vitro evaluated effectiveness of a polydopaminated polycaprolactone stent coated with dexamethasone‐eluting poly(lactic‐co‐glycolic) acid microparticles (μPLGA) for tracheal stenosis management. Polydopamination was characterized by Raman spectroscopy and promoted epithelialization while dexamethasone delivery reduced macrophage activity, assessed by individual cell area measurements and immunofluorescent staining for inducible nitric oxide synthase (iNOS). Dexamethasone release was quantified by high‐performance liquid chromatography over 30 days. Activation‐related increase in cell area and iNOS production by RAW 264.7 were both reduced significantly (p <.05) through dexamethasone release. Epithelial cell spreading was higher on polydopaminated polycaprolactone (PCL) than PCL‐alone (p <.05). Force required for stent migration was measured by pullout tests of PCL‐μPLGA stents from cadaveric rabbit and porcine tracheas (0.425 ± 0.068 N and 1.082 ± 0.064 N, respectively) were above forces estimated to occur during forced respiration. Biomechanical support provided by stents to prevent airway collapse was assessed by comparing compressive circumferential stiffness, and stiffness of the stent was about 1/10th of the rabbit trachea (0.156 ± 0.023 N/mm vs. 1.420 ± 0.194 N/mm, respectively). A dexamethasone‐loaded PCL‐μPLGA stent platform can deliver dexamethasone and exhibits sufficient mechanical properties to anchor within the trachea and polydopamination of PCL is conducive to epithelial layer formation. Therefore, a polydopaminated PCL‐μPLGA stent is a promising candidate for in vivo evaluation for treatment of tracheal restenosis. [ABSTRACT FROM AUTHOR]

Introduction: The sheep was evaluated as a potential model for preclinical evaluation of urethral slings in vivo based on: (1) anatomical measurements of the sheep vagina and (2) histological tissue integration and host response to polypropylene (PP) slings. Methods: Eight female, multiparous sheep were utilized. Three of 8 animals underwent surgery mimicking human tension-free vaginal tape protocols for midurethral slings and were euthanized at 6 months. The following measurements were obtained: vaginal length, maximum vaginal width with retraction, symphysis pubis length, and distance from the pubic bone to incision. Explanted sling samples from sheep and human were stained with hematoxylin and eosin for host reaction assessment. Results: Geometric measurements were similar between humans and sheep. Sheep vaginal anatomy allowed sling placement similar to procedures in human surgeries, and all sheep recovered without problems. Comparative histology between the sheep and human indicated similar host reaction and collagen deposition around implants, confirming suitability of the sheep model for biomaterial response assessment. Conclusion: Sheep vaginal length is comparable to humans. Tissue integration and host response to PP slings showed chronic inflammation with rich collagen deposition around the material in both sheep and human specimens, highlighting the sheep as a potential animal model for preclinical testing of midurethral slings. [ABSTRACT FROM AUTHOR]

Cortical bone allograft sterilized with a standard γ‐radiation dose of 25–35kGy has demonstrated reduced static and cyclic fracture resistance compared with unirradiated bone. To mitigate radiation damage, we recently observed a dose‐dependent response of high‐cycle fatigue behavior of human cortical bone from 0 to 25 kGy, with lower doses exhibiting logarithmically longer fatigue lives. The objectives of this study were as follows: (1) to determine whether fracture toughness, work‐to‐fracture, and fatigue crack propagation resistance of human cortical bone are also radiation dose‐dependent, and (2) to determine the associations of radiation dose and a Raman biomarker for collagen disorder with fracture properties. Compact tension specimens were machined from two donor femoral pairs and allocated to four treatment groups: 0 (unirradiated control), 10, 17.5, and 25 kGy. Fracture toughness specimens were monotonically loaded to failure and the critical stress intensity factor (KC) was determined. Work‐to‐fracture was calculated from the load versus displacement integral up to fracture. Fatigue crack propagation specimens were cyclically loaded under constant room‐temperature irrigation and fatigue crack growth rate (da/dN) and cyclic stress intensity (∆K) were calculated. Fracture toughness, work‐to‐fracture, and fatigue crack propagation resistance decreased 18%, 33%, and 15‐fold from 0 to 25 kGy, respectively (p < 0.05). Radiation dose was more predictive of fracture properties than collagen disorder. These findings support that quasi‐static and fatigue fracture properties of cortical bone are radiation dose‐dependent within this dose range. The structural alterations arising from irradiation that cause these losses in fracture resistance remain to be elucidated. [ABSTRACT FROM AUTHOR]