Local estradiol deposition in a rat rotator cuff repair model: proof of concept

Background: Local delivery of hormones could potentially provide local benefits to bone and enthesis while avoiding systemic side effects. The objective of this study was to demonstrate proof of concept for local deposition of estradiol in a rat rotator cuff repair model. Methods: First, in vitro el...

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Main Authors: Peter N. Chalmers, MD, Michael J. Jurynec, PhD, Austin M. Hickey, MS, T. Wade Fallin, MS, Antonio C. Zelada, BS, Matthew Honeggar, BS, James M. Hotaling, MD, Benjamin Emery, MPhil, Robert Tashjian, MD
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:JSES International
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666638325000866
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author Peter N. Chalmers, MD
Michael J. Jurynec, PhD
Austin M. Hickey, MS
T. Wade Fallin, MS
Antonio C. Zelada, BS
Matthew Honeggar, BS
James M. Hotaling, MD
Benjamin Emery, MPhil
Robert Tashjian, MD
author_facet Peter N. Chalmers, MD
Michael J. Jurynec, PhD
Austin M. Hickey, MS
T. Wade Fallin, MS
Antonio C. Zelada, BS
Matthew Honeggar, BS
James M. Hotaling, MD
Benjamin Emery, MPhil
Robert Tashjian, MD
author_sort Peter N. Chalmers, MD
collection DOAJ
description Background: Local delivery of hormones could potentially provide local benefits to bone and enthesis while avoiding systemic side effects. The objective of this study was to demonstrate proof of concept for local deposition of estradiol in a rat rotator cuff repair model. Methods: First, in vitro elution studies using an injection-molded polycaprolactone (PCL) implant were performed. Second, PCL rods laden with 5% estradiol were implanted within the greater tuberosity of 14 ovariectomized wild-type Sprague-Dawley rats with a concomitant rotator cuff repair. Rods without hormone were implanted in 4 ovariectomized rats and 4 intact rats as controls. We analyzed (1) postimplantation serum estradiol levels via enzyme-linked immunoassay, (2) tissue hormone levels via liquid chromatography-mass spectrometry, and (3) bone mineral density (BMD) of the postimplantation humerus via micro-computed tomography. Results: In vitro elution studies demonstrated 2 weeks of controlled estradiol release at an average daily dose of 10.9 μg/day, with continued release of at least 35 days. Serum estradiol levels significantly increased from 5 ± 1 preoperatively, to 972 ± 251, to 831 ± 477 pg/mL at 6 days postoperatively (P < .001). Tissue estradiol levels were significantly higher within the rotator cuff tendon adjacent to the implant (45.9 ± 80.3 pg/mg) than in control tendon tissues (1.4 ± 1.3 pg/mg; P = .002). Micro-computed tomography demonstrated significantly higher BMD adjacent to estradiol-laden implants than control implants at 6 days postoperatively (1462 ± 57 vs. 1291 ± 69 hydroxyapatite/cc; P < .001). Conclusion: This study demonstrates that a PCL implant is capable of sustained release of estradiol over 6 weeks and concentrates estradiol locally. Local deposition of estradiol increases local BMD rapidly.
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spelling doaj-art-e5008ab9b1364f31ac2c16b88123798f2025-08-20T02:36:50ZengElsevierJSES International2666-63832025-07-01941164117110.1016/j.jseint.2025.03.004Local estradiol deposition in a rat rotator cuff repair model: proof of conceptPeter N. Chalmers, MD0Michael J. Jurynec, PhD1Austin M. Hickey, MS2T. Wade Fallin, MS3Antonio C. Zelada, BS4Matthew Honeggar, BS5James M. Hotaling, MD6Benjamin Emery, MPhil7Robert Tashjian, MD8Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA; Corresponding author: Peter N. Chalmers, MD, Department of Orthopaedic Surgery, University of Utah, 590 Wakara Way, Salt Lake City, UT 84108, USA.Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USA; Department of Human Genetics, University of Utah, Salt Lake City, UT, USADepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USADepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USADepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USADepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USADivision of Urology, Department of Surgery, University of Utah, Salt Lake City, UT, USADivision of Urology, Department of Surgery, University of Utah, Salt Lake City, UT, USADepartment of Orthopaedic Surgery, University of Utah, Salt Lake City, UT, USABackground: Local delivery of hormones could potentially provide local benefits to bone and enthesis while avoiding systemic side effects. The objective of this study was to demonstrate proof of concept for local deposition of estradiol in a rat rotator cuff repair model. Methods: First, in vitro elution studies using an injection-molded polycaprolactone (PCL) implant were performed. Second, PCL rods laden with 5% estradiol were implanted within the greater tuberosity of 14 ovariectomized wild-type Sprague-Dawley rats with a concomitant rotator cuff repair. Rods without hormone were implanted in 4 ovariectomized rats and 4 intact rats as controls. We analyzed (1) postimplantation serum estradiol levels via enzyme-linked immunoassay, (2) tissue hormone levels via liquid chromatography-mass spectrometry, and (3) bone mineral density (BMD) of the postimplantation humerus via micro-computed tomography. Results: In vitro elution studies demonstrated 2 weeks of controlled estradiol release at an average daily dose of 10.9 μg/day, with continued release of at least 35 days. Serum estradiol levels significantly increased from 5 ± 1 preoperatively, to 972 ± 251, to 831 ± 477 pg/mL at 6 days postoperatively (P < .001). Tissue estradiol levels were significantly higher within the rotator cuff tendon adjacent to the implant (45.9 ± 80.3 pg/mg) than in control tendon tissues (1.4 ± 1.3 pg/mg; P = .002). Micro-computed tomography demonstrated significantly higher BMD adjacent to estradiol-laden implants than control implants at 6 days postoperatively (1462 ± 57 vs. 1291 ± 69 hydroxyapatite/cc; P < .001). Conclusion: This study demonstrates that a PCL implant is capable of sustained release of estradiol over 6 weeks and concentrates estradiol locally. Local deposition of estradiol increases local BMD rapidly.http://www.sciencedirect.com/science/article/pii/S2666638325000866Basic Science StudyIn-Vivo Animal Model
spellingShingle Peter N. Chalmers, MD
Michael J. Jurynec, PhD
Austin M. Hickey, MS
T. Wade Fallin, MS
Antonio C. Zelada, BS
Matthew Honeggar, BS
James M. Hotaling, MD
Benjamin Emery, MPhil
Robert Tashjian, MD
Local estradiol deposition in a rat rotator cuff repair model: proof of concept
JSES International
Basic Science Study
In-Vivo Animal Model
title Local estradiol deposition in a rat rotator cuff repair model: proof of concept
title_full Local estradiol deposition in a rat rotator cuff repair model: proof of concept
title_fullStr Local estradiol deposition in a rat rotator cuff repair model: proof of concept
title_full_unstemmed Local estradiol deposition in a rat rotator cuff repair model: proof of concept
title_short Local estradiol deposition in a rat rotator cuff repair model: proof of concept
title_sort local estradiol deposition in a rat rotator cuff repair model proof of concept
topic Basic Science Study
In-Vivo Animal Model
url http://www.sciencedirect.com/science/article/pii/S2666638325000866
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