Impact of adipose-derived stem cells on aortic tensile strength in a model of abdominal aortic aneurysm

Introduction: Abdominal Aortic Aneurysm (AAA) is a highly morbid condition and is the 11th leading cause of death in the United States. Treatment options are limited to operative interventions, with minimal non-operative options. Prior literature has demonstrated a benefit to the use of mesenchymal stem cells (MSCs) in attenuating AAA formation. We demonstrate the utility of MSCs in treating AAA in swine, focusing on the mechanical and structural characteristics of aortic tissue after treatment. Methods: 16 Yorkshire pigs underwent retroperitoneal exposure of the infrarenal aorta, with subsequent induction of AAA with peri-adventitial elastase and collagenase. A 1 × 4 cm piece of Gelfoam, an absorbable gelatin-based hemostatic agent, was soaked in media or human MSCs and placed directly on the vessel for control and experimental animals. At postoperative day 21, animals were sacrificed and the infrarenal aorta at this location was harvested for analysis. Tensile strength was measured using a tensiometer, from which Young's modulus and maximum strain were calculated. Results: All animals survived the surgery and post-operative course. Young's elastic modulus for the aneurysm control group was 15.83 ± 1.61 compared to 22.13 ± 2.34 for the stem cell treated segment, p = 0.0316. There was no significant difference in the peak stress between groups. Conclusions: This is the first study to demonstrate the mechanical effects of stem cell therapy on a model of AAA in swine. Young's modulus, which characterizes the intrinsic capacity of a tissue to withstand stress, was greater in the animals treated with MSCs compared to control animals with aneurysms. This methodology can be utilized in future large animal models to develop cell and drug-based therapies for AAA

STRUCTURAL ANALYSIS AND COMPREHENSIVE SURGICAL OUTCOMES OF THE SUTURELESS INTRASCLERAL FIXATION OF SECONDARY INTRAOCULAR LENSES IN HUMAN EYES.

PURPOSE: To describe surgical outcomes and structural characteristics of intraocular lenses (IOLs) implanted with transconjunctival sutureless intrascleral (SIS) fixation in human eyes. DESIGN: Retrospective interventional surgical case series involving live and cadaveric human eyes. METHODS: In this study, we investigated the surgical outcomes and structural anatomy of secondary IOLs implanted with the SIS technique in human eyes. All cases involving SIS IOL fixation performed at a single academic center from January 1, 2012, through July 30, 2016, were reviewed to describe the surgical technique, common indications, clinical outcomes, and the rate of common operative complications. To investigate the structure of SIS-fixated IOLs in vivo, slit-lamp biomicroscopy, ultrasound biomicroscopy, and intraoperative endoscopy were analyzed to describe anatomical outcomes. The primary anatomical outcomes were the optic pupillary centration and location of haptic externalization. Results were correlated with cadaveric human eyes that underwent the SIS-IOL technique. Cadaveric eyes were imaged and analyzed using high-resolution photography for centration, stress measurements at the haptic-optic junction, and qualitative descriptors of IOL optic and haptic position. RESULTS: A total of 122 consecutive patients who underwent IOL placement using SIS technique were included in the study with mean follow-up of 1.52 years (range, 0.4-4.5 years). The majority (75%) of patients received a new 3-piece IOL for primary aphakia or after IOL exchange. The other patients (25%) had a dislocated 3-piece IOL that was rescued using the SIS technique. Preoperative mean Snellen visual acuity was 20/633 (logarithm of the minimum angle of resolution = 1.501). At the final visit, the mean best-corrected visual acuity was 20/83 (logarithm of the minimum angle of resolution = 0.6243) and final mean spherical equivalent was -0.57 diopters. The most common complications were vitreous hemorrhage (22% of eyes), which resolved spontaneously in most cases, and cystoid macular edema. The rates of IOL dislocation, IOL decentration, haptic erosion, IOL tilting, iris capture, and endophthalmitis were low. Intraoperative endoscopy and ultrasound biomicroscopy demonstrated a securely fixated IOL and well-centered optic without iris or ciliary body touch. Structural study of cadaveric eyes confirmed IOL optic and haptic anatomy observed during live human surgery. The ab interno haptic insertion was the anterior pars plana, away from the iris, ciliary processes and ora serrata. The degree of haptic externalization was correlated with the degree of strain on the haptic-optic junction. The angle of the haptic-optic junction in SIS-fixated IOLs (33.97°) was not significantly different compared with overlaid native nonfixated IOL (32.93°) but increased slightly with degree of haptic tip externalization (36.26 and 39.16 for 2 and 3 mm haptic externalizations, respectively). CONCLUSION: In this comprehensive study, we demonstrate the surgical outcomes achieved with SIS fixation of IOLs. Surgical and postoperative complications do occur, albeit at a low rate, and can effectively be managed with excellent anatomical and visual outcomes. The structural and anatomical data in this study may help guide SIS placement and optimize long-term surgical results