Autologous Tenocyte Injection for the Treatment of Chronic Recalcitrant Gluteal Tendinopathy: A Prospective Pilot Study

Xenogeneic versus allogeneic serum and macromolecular crowding in human tenocyte cultures

Allogeneic serum and tissue-specific extracellular matrix have been shown to maintain permanently differentiated cell phenotype in culture. This is of particular importance for human tenocytes, a cell population that readily loses its function during ex vivo culture. With these in mind, herein we extracted human tenocytes using either foetal bovine serum or human serum, cultured them in the absence and presence of carrageenan and Ficoll®, the most widely used macromolecular crowding agents (to induce tissue-specific extracellular matrix deposition), and assessed cellular function, via metabolic activity, viability, proliferation and immunofluorescence for collagen related molecules, non-collagenous molecules and transmembrane molecules. At day 7, longest time point assessed, neither carrageenan nor Ficoll® significantly affected metabolic activity, viability and proliferation in either serum and human serum significantly increased metabolic activity and proliferation. At day 7, in the absence of macromolecular crowding, cells in human serum deposited significantly lower collagen type VI, biglycan, versican and tenomodulin than cells in foetal bovine serum. Interestingly, at day 7, in comparison to the no macromolecular crowding group, carrageenan in foetal bovine serum induced the highest effect, as judged by the highest number of significantly increased molecules (collagen type I, collagen type IV, collagen type V, collagen type VI, transforming growth factor β1, matrix metalloproteinase 14, lumican, versican, scleraxis and integrin α2β1). These data, although contradict previous observations where human serum outperformed foetal bovine serum, at the same time, support the use of foetal bovine serum in the development of cell-based medicines.

Macromolecular crowding in human tenocyte and skin fibroblast cultures: A comparative analysis

Although human tenocytes and dermal fibroblasts have shown promise in tendon engineering, no tissue engineered medicine has been developed due to the prolonged ex vivo time required to develop an implantable device. Considering that macromolecular crowding has the potential to substantially accelerate the development of functional tissue facsimiles, herein we compared human tenocyte and dermal fibroblast behaviour under standard and macromolecular crowding conditions to inform future studies in tendon engineering. Basic cell function analysis made apparent the innocuousness of macromolecular crowding for both cell types. Gene expression analysis of the without macromolecular crowding groups revealed expression of tendon related molecules in human dermal fibroblasts and tenocytes. Protein electrophoresis and immunocytochemistry analyses showed significantly increased and similar deposition of collagen fibres by macromolecular crowding in the two cell types. Proteomics analysis demonstrated great similarities between human tenocyte and dermal fibroblast cultures, as well as the induction of haemostatic, anti-microbial and tissue-protective proteins by macromolecular crowding in both cell populations. Collectively, these data rationalise the use of either human dermal fibroblasts or tenocytes in combination with macromolecular crowding in tendon engineering.

Is there structural change on MRI in gluteal tendinopathy after treatment? Single outcome measure extension of an RCT

BACKGROUND

The etiology of tendinopathy remains controversial and it is unknown whether degenerative structural changes in tendinopathies are reversible.

HYPOTHESIS

There will be no structural change on magnetic resonance imaging (MRI) taken > 2-years after treatment for gluteal tendinopathy.

STUDY DESIGN

Extension of a single site, double-blind, prospective randomized-controlled trial to analyze the additional outcome measure; MRI changes.

METHODS

University of Melbourne ethics approval number: 1852900, trial registration: ACTRN12613000677707. Participants with gluteal tendinopathy who had previously received a leukocyte-rich platelet-rich plasma injection (LR-PRP) or a corticosteroid injection (CSI) had a post treatment MRI between at least 2-years and up to 7 years following trial completion. A blinded, senior musculoskeletal radiologist graded all de-identified MRI scans using the Melbourne Hip Score (MHIP). The primary outcome measure was the change in overall pre- and post-treatment score.

RESULTS

Participants (n = 20) underwent MRI at mean time of 4.15 (SD 1.11; range 2-7) years after their initial treatment. There was no change in the overall mean MHIP score for the CSI group (Pre 4.3 (SD 2.3) Post 4.3 (SD 1.1), p = 1.00). Although there was an improvement in the LR-PRP group mean MHIP score (Pre 5.3 (SD 3.0) Post 4.77 (SD 2.5), p = 0.56) it was not statistically significant. However, in the LR-PRP intervention group, five out of nine of participants' MHIP score improved, with four of these improving by 2-4 points.

CONCLUSION

The hypothesis that there would be no improvement in MHIP scores following treatment of gluteal tendinopathy was supported. Findings of improvement in the LR-PRP group at 4 years would support further studies powered to look for structural improvement. These findings suggest that structural change following treatment for tendinopathy may be possible supporting the inclusion of MRI as a core outcome for future studies.

CLINICAL RELEVANCE

The study suggests that degenerative structural changes in tendons may be reversible.

Gluteal Tendinopathy: Critical Analysis Review of Current Nonoperative Treatments

» Gluteal tendinopathy/greater trochanteric pain syndrome (GTPS) is the most prevalent of all lower limb tendinopathies, affecting 1 in 4 women older than 50 years and commonly individuals within their fifth and sixth decades of life regardless of activity level.» The condition is believed to originate from age-related degenerative changes about the hip abductor tendon insertions and the surrounding bursae, and is exacerbated by congenital and acquired abnormal hip biomechanics.» Treatment of gluteal tendinopathy/GTPS often begins with noninvasive nonoperative modalities such as activity modifications, nonsteroidal anti-inflammatory drugs, and physical therapy. For recalcitrant symptoms, additional nonoperative therapies have been used; however, there remains a lack of comparative efficacy between these adjunct treatments.» In this article, we examine the available literature regarding the nonoperative management of gluteal tendinopathy/GTPS and provide insight into the effectiveness of current treatment modalities.

Bio-Enhanced Neoligaments Graft Bearing FE002 Primary Progenitor Tenocytes: Allogeneic Tissue Engineering & Surgical Proofs-of-Concept for Hand Ligament Regenerative Medicine

Hand tendon/ligament structural ruptures (tears, lacerations) often require surgical reconstruction and grafting, for the restauration of finger mechanical functions. Clinical-grade human primary progenitor tenocytes (FE002 cryopreserved progenitor cell source) have been previously proposed for diversified therapeutic uses within allogeneic tissue engineering and regenerative medicine applications. The aim of this study was to establish bioengineering and surgical proofs-of-concept for an artificial graft (Neoligaments Infinity-Lock 3 device) bearing cultured and viable FE002 primary progenitor tenocytes. Technical optimization and in vitro validation work showed that the combined preparations could be rapidly obtained (dynamic cell seeding of 10⁵ cells/cm of scaffold, 7 days of co-culture). The studied standardized transplants presented homogeneous cellular colonization in vitro (cellular alignment/coating along the scaffold fibers) and other critical functional attributes (tendon extracellular matrix component such as collagen I and aggrecan synthesis/deposition along the scaffold fibers). Notably, major safety- and functionality-related parameters/attributes of the FE002 cells/finished combination products were compiled and set forth (telomerase activity, adhesion and biological coating potentials). A two-part human cadaveric study enabled to establish clinical protocols for hand ligament cell-assisted surgery (ligamento-suspension plasty after trapeziectomy, thumb metacarpo-phalangeal ulnar collateral ligamentoplasty). Importantly, the aggregated experimental results clearly confirmed that functional and clinically usable allogeneic cell-scaffold combination products could be rapidly and robustly prepared for bio-enhanced hand ligament reconstruction. Major advantages of the considered bioengineered graft were discussed in light of existing clinical protocols based on autologous tenocyte transplantation. Overall, this study established proofs-of-concept for the translational development of a functional tissue engineering protocol in allogeneic musculoskeletal regenerative medicine, in view of a pilot clinical trial.

Tendinopathies and Allied Disorders of the Hip

There are many soft tissue structures around the hip joint that may serve as a source of pain in both the native and prosthetic hip. In this review, the role of the gluteal, piriformis, iliopsoas, and rectus femoris musculotendinous units in the etiology of pathology around the hip joint will be discussed. Management options ranging from tailored physical therapy regimens to local steroid infiltration along with more invasive open and arthroscopic surgical techniques will be reviewed for each pathological entity. While not all conditions are well understood, advancements have been made in the management of each of these often challenging cases in both the native and prosthetic hip settings. This review explores these advancing treatment methods which will supplement the practice of any hip surgeon who is presented with problematic tendinopathy around both the native and prosthetic hip joint.

Challenges and perspectives of tendon-derived cell therapy for tendinopathy: from bench to bedside

Tendon is composed of dense fibrous connective tissues, connecting muscle at the myotendinous junction (MTJ) to bone at the enthesis and allowing mechanical force to transmit from muscle to bone. Tendon diseases occur at different zones of the tendon, including enthesis, MTJ and midsubstance of the tendon, due to a variety of environmental and genetic factors which consequently result in different frequencies and recovery rates. Self-healing properties of tendons are limited, and cell therapeutic approaches in which injured tendon tissues are renewed by cell replenishment are highly sought after. Homologous use of individual’s tendon-derived cells, predominantly differentiated tenocytes and tendon-derived stem cells, is emerging as a treatment for tendinopathy through achieving minimal cell manipulation for clinical use. This is the first review summarizing the progress of tendon-derived cell therapy in clinical use and its challenges due to the structural complexity of tendons, heterogeneous composition of extracellular cell matrix and cells and unsuitable cell sources. Further to that, novel future perspectives to improve therapeutic effect in tendon-derived cell therapy based on current basic knowledge are discussed.

Treatment of Gluteal Tendinopathy: A Systematic Review and Stage-Adjusted Treatment Recommendation

Background:

Gluteal tendinopathy is the most common lower limb tendinopathy. It presents with varying severity but may cause debilitating lateral hip pain.

Purpose:

To review the therapeutic options for different stages of gluteal tendinopathy, to highlight gaps within the existing evidence, and to provide guidelines for a stage-adjusted therapy for gluteal tendinopathy.

Study Design:

Systematic review; Level of evidence, 4.

Methods:

We screened Scopus, Embase, Web of Science, PubMed, PubMed Central, Ovid MEDLINE, CINAHL, UpToDate, and Google Scholar databases and databases for grey literature. Patient selection, diagnostic criteria, type and effect of a therapeutic intervention, details regarding aftercare, outcome assessments, complications of the treatment, follow-up, and conclusion of the authors were recorded. An assessment of study methodological quality (type of study, level of evidence) was also performed. Statistical analysis was descriptive. Data from multiple studies were combined if they were obtained from a single patient population. Weighted mean and range calculations were performed.

Results:

A total of 27 studies (6 randomized controlled trials) with 1103 patients (1106 hips) were included. The mean age was 53.7 years (range, 17-88 years), and the mean body mass index was 28.3. The ratio of female to male patients was 7:1. Radiological confirmation of the diagnosis was most commonly obtained using magnetic resonance imaging. Reported treatment methods were physical therapy/exercise; injections (corticosteroids, platelet-rich plasma, autologous tenocytes) with or without needle tenotomy/tendon fenestration; shockwave therapy; therapeutic ultrasound; and surgical procedures such as bursectomy, iliotibial band release, and endoscopic or open tendon repair (with or without tendon augmentation).

Conclusion:

There was good evidence for using platelet-rich plasma in grades 1 and 2 tendinopathy. Shockwave therapy, exercise, and corticosteroids showed good outcomes, but the effect of corticosteroids was short term. Bursectomy with or without iliotibial band release was a valuable treatment option in grades 1 and 2 tendinopathy. Insufficient evidence was available to provide guidelines for the treatment of partial-thickness tears. There was low-level evidence to support surgical repair for grades 3 (partial-thickness tears) and 4 (full-thickness tears) tendinopathy. Fatty degeneration, atrophy, and retraction can impair surgical repair, while their effect on patient outcomes remains controversial.

Reliability of a Novel Scoring System for MRI Assessment of Severity in Gluteal Tendinopathy: The Melbourne Hip MRI Score

Background

Gluteal tendinopathy is commonly reported in the literature, but there is a need for a validated magnetic resonance imaging (MRI)-based scoring system to grade the severity of the tendinopathy.

Purpose

To use intra- and interobserver reliability to validate a new scoring system, the Melbourne Hip MRI (MHIP) score, for assessing the severity of gluteal tendinopathy.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

The MHIP score assesses gluteal tendinopathy according to each 1 of 5 categories: (1) extent of tendon pathology (maximum 5 points); (2) muscle atrophy (maximum 4 points); (3) trochanteric bursitis (maximum 4 points); (4) cortical irregularity (maximum 3 points); and (5) bone marrow edema (maximum 1 point), with an overall range of 0 to 17 (most severe). A total of 41 deidentified MRI scans from 40 patients diagnosed with gluteal tendinopathy (mean baseline age, 57.44 ± 25.26 years; 4 male, 36 female) were read and graded according to MHIP criteria by 2 experienced musculoskeletal radiologists. The radiologists were blinded to previous reports, and the scans were read twice within a 2-month period. Statistical analysis using the intraclass correlation coefficient (ICC) was used to determine intra- and interobserver reliability and mean/range for the MHIP scores.

Results

Of a total of 123 readings, the mean MHIP score (±SD) was 3.93 ± 2.24 (range, 0-17 points). The MHIP score demonstrated excellent reliability for determining the severity of gluteal tendinopathy on MRI. The ICC for intra- and interobserver reliability was 0.81 (95% CI, 0.67-0.89) and 0.78 (95% CI, 0.62-0.87), respectively.

Conclusion

The MHIP score had excellent intra- and interobserver reliability in scoring gluteal tendinopathy. This score allows gluteal tendon pathology to be graded prior to treatment and to be used for standardized comparisons between results in future research undertaking radiological review of gluteal tendinopathy.

Identification and Distinction of Tenocytes and Tendon-Derived Stem Cells

Restoring the normal structure and function of injured tendons is one of the biggest challenges in orthopedics and sports medicine department. The discovery of tendon-derived stem cells (TDSCs) provides a novel perspective to treat tendon injuries, which is expected to be an ideal seed cell to promote tendon repair and regeneration. Because of the lack of specific markers, the identification of tenocytes and TDSCs has not been conclusive in the in vitro study of tendons. In addition, the morphology of tendon derived cells is similar, and the comparison and identification of tenocytes and TDSCs are insufficient, which causes some obstacles to the in vitro study of tendon. In this review, the characteristics of tenocytes and TDSCs are summarized and compared based on some existing research results (mainly in terms of biomarkers), and a potential marker selection for identification is suggested. It is of profound significance to further explore the mechanism of biomarkers in vivo and to find more specific markers.

Supporting Cell-Based Tendon Therapy: Effect of PDGF-BB and Ascorbic Acid on Rabbit Achilles Tenocytes in Vitro

Cell-based tendon therapies with tenocytes as a cell source need effective tenocyte in vitro expansion before application for tendinopathies and tendon injuries. Supplementation of tenocyte culture with biomolecules that can boost proliferation and matrix synthesis is one viable option for supporting cell expansion. In this in vitro study, the impacts of ascorbic acid or PDGF-BB supplementation on rabbit Achilles tenocyte culture were studied. Namely, cell proliferation, changes in gene expression of several ECM and tendon markers (collagen I, collagen III, fibronectin, aggrecan, biglycan, decorin, ki67, tenascin-C, tenomodulin, Mohawk, α-SMA, MMP-2, MMP-9, TIMP1, and TIMP2) and ECM deposition (collagen I and fibronectin) were assessed. Ascorbic acid and PDGF-BB enhanced tenocyte proliferation, while ascorbic acid significantly accelerated the deposition of collagen I. Both biomolecules led to different changes in the gene expression profile of the cultured tenocytes, where upregulation of collagen I, Mohawk, decorin, MMP-2, and TIMP-2 was observed with ascorbic acid, while these markers were downregulated by PDGF-BB supplementation. Vice versa, there was an upregulation of fibronectin, biglycan and tenascin-C by PDGF-BB supplementation, while ascorbic acid led to a downregulation of these markers. However, both biomolecules are promising candidates for improving and accelerating the in vitro expansion of tenocytes, which is vital for various tendon tissue engineering approaches or cell-based tendon therapy.

Stem Cell Therapy for Tendon Regeneration: Current Status and Future Directions

In adults the healing tendon generates fibrovascular scar tissue and recovers never histologically, mechanically, and functionally which leads to chronic and to degenerative diseases. In this review, the processes and mechanisms of tendon development and fetal regeneration in comparison to adult defect repair and degeneration are discussed in relation to regenerative therapeutic options. We focused on the application of stem cells, growth factors, transcription factors, and gene therapy in tendon injury therapies in order to intervene the scarring process and to induce functional regeneration of the lesioned tissue. Outlines for future therapeutic approaches for tendon injuries will be provided.

Gluteus medius tears of the hip: a comprehensive approach

Greater trochanteric pain syndrome (GTPS) is a common clinical condition that can affect a wide range of patients. Historically, the condition has been associated with trochanteric bursitis. More recently, however, a growing body of literature has demonstrated gluteus medius tendinopathy and tearing is present in many cases of GTPS. Pathology of the gluteus medius can result in significant hip pain, loss of motion, and decreased function. Affected patients characteristically have symptoms including lateral hip pain and a Trendelenburg gait, which may be refractory to conservative management such as non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy, and injections. In these cases, both open and arthroscopic repair techniques have been described, with recent literature demonstrating excellent patient-reported outcomes. We present a comprehensive review of gluteus medius tears including relevant anatomy, clinical evaluation, diagnosis, and treatment options.

Identification of topographical architectures supporting the phenotype of rat tenocytes

Tenocytes, the main cell type of the tendon, require mechanical stimuli for their proper function. When the tenocyte environment changes due to tissue damage or by transferring tenocytes from their native environment into cell culture, the signals from the tenocyte niche are lost, leading towards a decline of phenotypic markers. It is known that micro-topographies can influence cell fate by the physical cues they provide. To identify the optimal topography-induced biomechanical niche in vitro, we seeded tenocytes on the TopoChip, a micro-topographical screening platform, and measured expression of the tendon transcription factor Scleraxis. Through machine learning algorithms, we associated elevated Scleraxis levels with topological design parameters. Fabricating micro-topographies with optimal surface characteristics on larger surfaces allowed finding an improved expression of multiple tenogenic markers. However, long-term confluent culture conditions coincided with osteogenic marker expression and the loss of morphological characteristics. In contrast, passaging tenocytes which migrated from the tendon directly on the topography resulted in prolonged elongated morphology and elevated Scleraxis levels. This research provides new insights into how micro-topographies influence tenocyte cell fate, and supports the notion that micro-topographical design can be implemented in a new generation of tissue culture platforms for supporting the phenotype of tenocytes. STATEMENT OF SIGNIFICANCE: The challenge in controlling in vitro cell behavior lies in controlling the complex culture environment. Here, we present for the first time the use of micro-topographies as a biomechanical niche to support the phenotype of tenocytes. For this, we applied the TopoChip platform, a screening tool with 2176 unique micro-topographies for identifying feature characteristics associated with elevated Scleraxis expression, a tendon related marker. Large area fabrication of micro-topographies with favorable characteristics allowed us to find a beneficial influence on other tenogenic markers as well. Furthermore, passaging cells is more beneficial for Scleraxis marker expression and tenocyte morphology compared to confluent conditions. This study presents important insights for the understanding of tenocyte behavior in vitro, a necessary step towards tendon engineering.

Effect of a Collagen-Based Compound on Morpho-Functional Properties of Cultured Human Tenocytes

Background: Greater Trochanter Pain Syndrome (GTPS) is the main reason for recalcitrant lateral hip pain. Gluteus medius and minimus tendinopathy plays a key role in this setting. An injectable medical compound containing collagen type I (MD-Tissue, Guna) has been produced with the aim to counteract the physiological and pathological degeneration of tendons. In this study we aimed at characterizing the effect of this medical compound on cultured human gluteal tenocytes, focusing on the collagen turnover pathways, in order to understand how this medical compound could influence tendon biology and healing. Methods: Tenocytes were obtained from gluteal tendon fragments collected in eight patients without any gluteal tendon pathology undergoing total hip replacement through an anterior approach. Cell proliferation and migration were investigated by growth curves and wound healing assay, respectively. The expression of genes and proteins involved in collagen turnover were analysed by real-time PCR, Slot blot and SDS-zymography. Results: Our data show that tenocytes cultured on MD-Tissue, compared to controls, have increased proliferation rate and migration potential. MD-Tissue induced collagen type I (COL-I) secretion and mRNA levels of tissue inhibitor of matrix metalloproteinases (MMP)-1 (TIMP-1). Meanwhile, lysyl hydroxylase 2b and matrix metalloproteinases (MMP)-1 and -2, involved, respectively, in collagen maturation and degradation, were not affected. Conclusions: Considered as a whole, our results suggest that MD-Tissue could induce in tenocytes an anabolic phenotype by stimulating tenocyte proliferation and migration and COL-I synthesis, maturation, and secretion, thus favouring tendon repair. In particular, based on its effect on gluteal tenocytes, MD-Tissue could be effective in the discouraging treatment of GTPS. From now a rigorous clinical investigation is desirable to understand the real clinical potentials of this compound.

Rescue plan for Achilles: Therapeutics steering the fate and functions of stem cells in tendon wound healing

Due to the increasing age of our society and a rise in engagement of young people in extreme and/or competitive sports, both tendinopathies and tendon ruptures present a clinical and financial challenge. Tendon has limited natural healing capacity and often responds poorly to treatments, hence it requires prolonged rehabilitation in most cases. Till today, none of the therapeutic options has provided successful long-term solutions, meaning that repaired tendons do not recover their complete strength and functionality. Our understanding of tendon biology and healing increases only slowly and the development of new treatment options is insufficient. In this review, following discussion on tendon structure, healing and the clinical relevance of tendon injury, we aim to elucidate the role of stem cells in tendon healing and discuss new possibilities to enhance stem cell treatment of injured tendon. To date, studies mainly apply stem cells, often in combination with scaffolds or growth factors, to surgically created tendon defects. Deeper understanding of how stem cells and vasculature in the healing tendon react to growth factors, common drugs used to treat injured tendons and promising cellular boosters could help to develop new and more efficient ways to manage tendon injuries.

Current advances in the treatment of medial and lateral epicondylitis

Despite advances elucidating the causes of lateral and medial epicondylitis, the standard of care remains conservative management with NSAIDs, physical therapy, bracing, and rest. Scar tissue formation provoked by conservative management creates a tendon lacking the biomechanical properties and mechanical strength of normal tendon. The following review analyzes novel therapies to regenerate tendon and regain function in patients with epicondylitis. These treatments include PRP injection, BMAC, collagen-producing cell injection, and stem cell treatments. While these treatments are in early stages of investigation, they may warrant further consideration based on prospects of pain alleviation, function enhancement, and improved healing.