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Little D, Amadio PC, Awad HA, Cone SG, Dyment NA, Fisher MB, Huang AH, Koch DW, Kuntz AF, Madi R, McGilvray K, Schnabel LV, Shetye SS, Thomopoulos S, Zhao C, Soslowsky LJ. Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how). J Orthop Res 2023; 41:2133-2162. [PMID: 37573480 PMCID: PMC10561191 DOI: 10.1002/jor.25678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/21/2023] [Accepted: 08/02/2023] [Indexed: 08/14/2023]
Abstract
Several tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: "Why, Who, What, Where, When, and How" (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.
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Affiliation(s)
- Dianne Little
- Department of Basic Medical Sciences, The Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Peter C Amadio
- Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Hani A Awad
- Department of Orthopaedics, Department of Biomedical Engineering, The Center for Musculoskeletal Research, University of Rochester, Rochester, New York, USA
| | - Stephanie G Cone
- Department of Biomedical Engineering, University of Delaware, Newark, Delaware, USA
| | - Nathaniel A Dyment
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Matthew B Fisher
- Joint Department of Biomedical Engineering, College of Engineering, North Carolina State University-University of North Carolina at Chapel Hill, Raleigh, North Carolina, USA
| | - Alice H Huang
- Department of Orthopedic Surgery, Department of Biomedical Engineering, Columbia University, New York, New York, USA
| | - Drew W Koch
- Department of Clinical Sciences, College of Veterinary Medicine, and Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, USA
| | - Andrew F Kuntz
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rashad Madi
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kirk McGilvray
- Department of Mechanical Engineering, School of Biomedical Engineering, Colorado State University, Fort Collins, Colorado, USA
| | - Lauren V Schnabel
- Department of Clinical Sciences, College of Veterinary Medicine, and Comparative Medicine Institute, North Carolina State University, Raleigh, North Carolina, USA
| | - Snehal S Shetye
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stavros Thomopoulos
- Department of Orthopedic Surgery, Department of Biomedical Engineering, Columbia University, New York, New York, USA
| | - Chunfeng Zhao
- Department of Orthopaedic Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Louis J Soslowsky
- McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Disser NP, Piacentini AN, De Micheli AJ, Schonk MM, Yao VJH, Deng XH, Oliver DJ, Rodeo SA. Achilles Tendons Display Region-Specific Transcriptomic Signatures Associated With Distinct Mechanical Properties. Am J Sports Med 2022; 50:3866-3874. [PMID: 36305762 DOI: 10.1177/03635465221128589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Previous studies have examined the transcriptomes and mechanical properties of whole tendons in different regions of the body. However, less is known about these characteristics within a single tendon. PURPOSE To develop a regional transcriptomic atlas and evaluate the region-specific mechanical properties of Achilles tendons. STUDY DESIGN Descriptive laboratory study. METHODS Achilles tendons from 2-month-old male Sprague Dawley rats were used. Tendons were isolated and divided into proximal, middle, and distal thirds for RNA sequencing (n = 5). For mechanical testing, the Achilles muscle-tendon-calcaneus unit was mounted in a custom-designed materials testing system with the unit clamped over the musculotendinous junction (MTJ) and the calcaneus secured at 90° of dorsiflexion (n = 9). Tendons were stretched to 20 N at a constant speed of 0.0167 mm/s. Cross-sectional area, strain, stress, and Young modulus were determined in each tendon region. RESULTS An open-access, interactive transcriptional atlas was generated that revealed distinct gene expression signatures in each tendon region. The proximal and distal regions had the largest differences in gene expression, with 2596 genes significantly differentially regulated at least 1.5-fold (q < .01). The proximal tendon displayed increased expression of genes resembling a tendon phenotype and increased expression of nerve cell markers. The distal region displayed increases in genes involved in extracellular matrix synthesis and remodeling, immune cell regulation, and a phenotype similar to cartilage and bone. There was a 3.72-fold increase in Young modulus from the proximal to middle region (P < .01) and an additional 1.34-fold increase from the middle to distal region (P = .027). CONCLUSION Within a single tendon, there are region-specific transcriptomic signatures and mechanical properties, and there is likely a gradient in the biological and functional phenotype from the proximal origin at the MTJ to the distal insertion at the enthesis. CLINICAL RELEVANCE These findings improve our understanding of the underlying biological heterogeneity of tendon tissue and will help inform the future targeted use of regenerative medicine and tissue engineering strategies for patients with tendon disorders.
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Affiliation(s)
- Nathaniel P Disser
- Hospital for Special Surgery, New York, New York, USA.,McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | | | - Andrea J De Micheli
- Hospital for Special Surgery, New York, New York, USA.,Department of Oncology of the Children's Research Center, University Children's Hospital Zürich, Zürich, Switzerland
| | | | - Vincent J H Yao
- Hospital for Special Surgery, New York, New York, USA.,Sophie Davis Biomedical Education Program at CUNY School of Medicine, New York, New York, USA
| | | | - David J Oliver
- Hospital for Special Surgery, New York, New York, USA.,The David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, New York, USA
| | - Scott A Rodeo
- Hospital for Special Surgery, New York, New York, USA
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Leahy T, Nuss C, Evans MK, Fung A, Shetye S, Soslowsky LJ. Achilles Tendon Ruptures in Middle-Aged Rats Heal Poorly Compared With Those in Young and Old Rats [Formula: see text]. Am J Sports Med 2022; 50:170-181. [PMID: 34851182 PMCID: PMC8819270 DOI: 10.1177/03635465211055476] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Achilles tendon ruptures are painful and debilitating injuries and are most common in middle-aged patients. There is a lack of understanding of the underlying causes for increased rupture rates in middle-aged patients and how healing outcomes after a rupture might be affected by patient age. Therefore, the objective of this study was to define age-specific Achilles tendon healing by assessing ankle functional outcomes and Achilles tendon mechanical and histological properties after a rupture using a rat model. HYPOTHESIS Rats representing the middle-aged patient population would demonstrate reduced healing capability after an Achilles tendon rupture, as demonstrated by a slower return to baseline ankle functional properties and inferior biomechanical and histological tendon properties. STUDY DESIGN Controlled laboratory study. METHODS Fischer 344 rats were categorized by age to represent young, middle-aged, and old patients, and Achilles tendon ruptures were induced in the right hindlimb. Animals were allowed to heal and were euthanized at 3 or 6 weeks after the injury. In vivo functional assays and ultrasound imaging were performed throughout the healing period, and ex vivo tendon mechanical and histological properties were assessed after euthanasia. RESULTS Rats representing middle-aged patients displayed reduced healing potential compared with the other age groups, as they demonstrated decreased recovery of in vivo functional and ultrasound assessment parameters and inferior mechanical and histological properties after an Achilles tendon rupture. CONCLUSION These findings may help explain the increased rupture rate observed clinically in middle-aged patients by suggesting that there may be altered tendon responses to daily trauma. CLINICAL RELEVANCE The results provide novel data on age-specific healing outcomes after an Achilles tendon rupture, which underscores the importance of considering a patient's age during treatment and expectations for outcomes.
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Affiliation(s)
- Thomas Leahy
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Courtney Nuss
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
| | - Mary Kate Evans
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Ashley Fung
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Snehal Shetye
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
| | - Louis J. Soslowsky
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, PA, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, USA
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Mienaltowski MJ, Gonzales NL, Beall JM, Pechanec MY. Basic Structure, Physiology, and Biochemistry of Connective Tissues and Extracellular Matrix Collagens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1348:5-43. [PMID: 34807414 DOI: 10.1007/978-3-030-80614-9_2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The physiology of connective tissues like tendons and ligaments is highly dependent upon the collagens and other such extracellular matrix molecules hierarchically organized within the tissues. By dry weight, connective tissues are mostly composed of fibrillar collagens. However, several other forms of collagens play essential roles in the regulation of fibrillar collagen organization and assembly, in the establishment of basement membrane networks that provide support for vasculature for connective tissues, and in the formation of extensive filamentous networks that allow for cell-extracellular matrix interactions as well as maintain connective tissue integrity. The structures and functions of these collagens are discussed in this chapter. Furthermore, collagen synthesis is a multi-step process that includes gene transcription, translation, post-translational modifications within the cell, triple helix formation, extracellular secretion, extracellular modifications, and then fibril assembly, fibril modifications, and fiber formation. Each step of collagen synthesis and fibril assembly is highly dependent upon the biochemical structure of the collagen molecules created and how they are modified in the cases of development and maturation. Likewise, when the biochemical structures of collagens or are compromised or these molecules are deficient in the tissues - in developmental diseases, degenerative conditions, or injuries - then the ultimate form and function of the connective tissues are impaired. In this chapter, we also review how biochemistry plays a role in each of the processes involved in collagen synthesis and assembly, and we describe differences seen by anatomical location and region within tendons. Moreover, we discuss how the structures of the molecules, fibrils, and fibers contribute to connective tissue physiology in health, and in pathology with injury and repair.
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Affiliation(s)
| | - Nicole L Gonzales
- Department of Animal Science, University of California Davis, Davis, CA, USA
| | - Jessica M Beall
- Department of Animal Science, University of California Davis, Davis, CA, USA
| | - Monica Y Pechanec
- Department of Animal Science, University of California Davis, Davis, CA, USA
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Counihan M, Leahy T, Nuss C, Newton J, Mohanty S, Soslowsky LJ, Farber D. Limited Scar Resection for Chronic Achilles Tendon Repair: Use of a Rat Model. Am J Sports Med 2021; 49:2707-2715. [PMID: 34197235 PMCID: PMC8653705 DOI: 10.1177/03635465211023096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Achilles tendon rupture diagnosis is frequently missed, leading to the development of a chronic rupture that requires surgical intervention to remove scar tissue and return the elongated Achilles tendon to appropriate functional length. The limited scar resection (LSR) intervention strategy may provide an advantage over other techniques, as it is less invasive and nondestructive to other tissues, although there is little evidence comparing outcomes between intervention strategies. HYPOTHESIS The LSR technique would be a viable treatment option for chronic Achilles tendon ruptures and would perform comparably with a more clinically accepted procedure, the gastrocnemius fascial turndown (GFT), in postintervention functional outcome measures and tendon mechanical and histological properties. STUDY DESIGN Controlled laboratory study. METHODS Chronic Achilles tendon ruptures were induced in the right hindlimb of Sprague-Dawley rats by Achilles tendon transection without repair, immobilization in dorsiflexion, and 5 weeks of cage activity. Animals were randomly divided between the intervention strategy groups (LSR and GFT), received 1 week of immobilization in plantarflexion, and were sacrificed at 3 or 6 weeks postintervention. In vivo functional outcome measures (gait kinetics, passive joint function, tendon vascular perfusion) were quantified during healing, and tendon mechanical and histological properties were assessed postsacrifice. RESULTS When compared with the GFT, the LSR technique elicited a faster return to baseline in gait kinetics, although there were few differences between groups or with healing time in other functional outcome measures (passive joint function and vascular perfusion). Quasi-static mechanical properties were improved with healing in both surgical intervention groups, although only the LSR group showed an improvement in fatigue properties between 3 and 6 weeks postintervention. Histological properties were similar between intervention strategies, except for decreased cellularity in the LSR group at 6 weeks postintervention. CONCLUSION The LSR technique is a viable surgical intervention strategy for a chronic Achilles tendon rupture in a rodent model, and it performs similarly, if not better, when directly compared with a more clinically accepted surgery, the GFT. CLINICAL RELEVANCE This study supports the increased clinical use of the LSR technique for treating chronic Achilles tendon rupture cases.
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Affiliation(s)
- Matthew Counihan
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Thomas Leahy
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Courtney Nuss
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph Newton
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sarthak Mohanty
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Louis J. Soslowsky
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniel Farber
- McKay Orthopaedic Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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