Autologous tenocyte implantation, a novel treatment for partial-thickness rotator cuff tear and tendinopathy in an elite athlete

Impact of age and donor sites on bioactivities of tendon cells in autologous tenocyte implantation (OrthoATI™) for treatment of chronic tendinopathy

OBJECTIVES

Autologous tenocyte implantation (OrthoATI™) therapy has demonstrated efficacy in treating patients with tendinopathy at various anatomical sites. This study evaluates the effect of patient age, gender, and tendon biopsy site on morphology, growth, and gene expression of autologous tendon cells used to treat chronic tendinopathy.

METHODS

Patients undergoing OrthoATI™ for tendinopathies between 2020 and 2022 were initially treated by biopsies taken from patella tendon (PT) or palmaris longus tendon (PL). The biopsies were sent to a Good Manufacturing Practice (GMP) cell laboratory where tendon cells were isolated, cultured, and expanded for four to six weeks. Cell morphology was assessed using phase contrast microscopy. Droplet digital PCR (ddPCR) was utilized for gene expression analysis. Dichotomous results were compared between groups using x2 or Fisher's exact tests with no adjustment for multiple comparisons. The nonparametric Mann-Whitney U and Kruskal-Wallis tests were utilized for the sex and age (<35y, 35-44y, 45-54y, >55y) analyses, respectively. All analyses were performed using IBM SPSS v27, and a two-tailed P-value of <0.05 was considered statistically significant.

RESULTS

149 patients were included in the analysis. The PT was biopsied in 63 patients, and PL in 86 patients. There were no observer effects for age and gender between the PT and PL groups. There was no statistical significance between the PT and PL tendons for cell morphology, average cell population doubling time (PDT) (PT 83.9 vs PL 82.7 ​h, p ​= ​0.482), cellular yield (PT 16.2 vs PL 15.2 ​× ​106, p ​= ​0.099), and cell viability (PT 98.7 vs PL 99.0%, p ​= ​0.277). Additionally, ddPCR analyses showed no statistical significance found in tenogenic gene expression, including collagen type I (COL1, p ​= ​0.86), tenomodulin (TNMD, p ​= ​0.837) and scleraxis (SCX, p ​= ​0.331) between PT- and PL-derived tendon cells. An age stratification analysis found no effect on growth and gene expression. COL1 was found to be higher in males when compared to females (P ​< ​0.001), but otherwise no difference was seen in growth and gene expression in the gender analysis. No postbiopsy clinical complications were reported for either group.

CONCLUSION

This study has shown that the growth and bioactivities of tendon cells from tendon biopsies for OrthoATI™ are not affected by tendon donor site and age.

LEVEL OF EVIDENCE

IV.

Arthroscopic Autologous Coracoacromial Ligament Augment Technique for Particle Thickness of Rotator Cuff with at Least Two Years Follow-Up

OBJECTIVE

Patch technology has been the new technique in the treatment of partial thickness of the rotator cuff tear (PTRCTs) to address the limitation of traditional techniques. Compared with allogeneic patches and artificial materials, coracoacromial ligament is obviously closer to their own biology. The purpose of the study was to evaluate the functional and radiographic outcomes following arthroscopic autologous coracoacromial ligament augment technique for treatment of PTRCTs.

METHOD

This study included three female patients with PTRCTs who underwent arthroscopy operation in 2017 with an average age of 51 years (range from 50 to 52 years). The coracoacromial ligament implant was attached to the bursal side surface of the tendon. The clinical results were evaluated by American Shoulder and Elbow Surgeons (ASES) score, Simple Shoulder Test (SST), acromiohumeral distance (AHD) and muscle strength before and 12 months after operation. Magnetic resonance imaging (MRI) was performed 24 months after operation to assess the integrity of the anatomical structure of the original tear site.

RESULT

The average ASES score improved significantly from 57.3 preoperatively to 95.0 at 1-year follow-up. The strength improved significantly from grade 3 preoperatively to grade 5 at 1 year. Two of three patients underwent the MRI at 2-year follow-up. Radiographic released the complete healing of rotator cuff tear. No implant-related serious adverse events were reported.

CONCLUSION

The new technique of using autogenous coracoacromial ligament patch augment provides good clinical results on patients with PTRCTs.

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.

Rotator Cuff Tendon Healing Using Human Dermal Fibroblasts: Histological and Biomechanical Analyses in a Rabbit Model of Chronic Rotator Cuff Tears

BACKGROUND

Tenocytes derived from tendons have been reported to be effective in the treatment of rotator cuff tears through the expression of extracellular matrix proteins. Human dermal fibroblasts, known to express collagen types I and III as tenocytes do, may likely be substitutes for tenocytes to enhance healing rotator cuff tears.

PURPOSE

To demonstrate the capability of human dermal fibroblasts to enhance healing of rotator cuff tears.

STUDY DESIGN

Controlled laboratory study.

METHODS

The cellular properties and expression profiles of growth factors were compared between human dermal fibroblasts and tenocytes. In both cell types, a series of extracellular matrix proteins were analyzed along with matrix metalloproteinases and tissue inhibitors of metalloproteinases involved in the collagenolytic system. A total of 35 rabbits were divided into 5 groups: normal (n = 2), saline control (n = 9), fibrin control (n = 9), low dose of human fibroblasts (HF-LD; n = 9), and high dose of human fibroblasts (HF-HD; n = 6). Cells were injected into the sutured lesions at 6 weeks after creation of bilateral rotator cuff tears, followed by histological and biomechanical analyses at 12 weeks.

RESULTS

Human dermal fibroblasts exhibited a protein expression pattern similar to that of tenocytes. More specifically, the expression levels of collagen types I and III were comparable between fibroblasts and tenocytes. The histological analysis of 30 surviving rabbits showed that collagen fibers were more continuous and better oriented with a more mature interface between the tendon and bone in the sutured lesions in the HF-LD and HF-HD groups. Most importantly, biomechanical strength, measured using the load to failure at the injection site, was 58.8 ± 8.9 N/kg in the HF-HD group, increasing by approximately 2-fold (P = .0003) over the saline control group.

CONCLUSION

Human dermal fibroblasts, showing cellular properties comparable with tenocytes, effectively enhanced healing of chronic rotator cuff tears in rabbits.

CLINICAL RELEVANCE

Human dermal fibroblasts can be used in place of tenocytes to enhance healing of rotator cuff tears.

Cell-based therapies for the treatment of sports injuries of the upper limb

Introduction: The use of cell-based therapies in the management of sports injuries of the upper limb is increasingly popular despite the limited scientific evidence available for their use. We aim to evaluate the evidence for the use of cell-based therapies in these injuries and recommend areas for further research.Areas covered: In accordance with a published protocol (PROSPERO; Registration No. CRD42020193258), a comprehensive search of the literature was performed using the MEDLINE and EMBASE databases from inception to June 2020. All human studies reporting on the clinical, histological, or radiological outcomes following the use of cell-based therapies in the management of epicondylitis or rotator cuff pathology were included in this study. This resulted in 22 studies being included in this review, all of which underwent risk of bias assessments.Expert opinion: The evidence for the use of cell-based therapies in upper limb sports injuries is limited and generally of low quality. Given the heterogeneity in the cell types used, their harvesting methods and cell amounts, future research should be targeted at developing standardization of the reporting of these studies and more direct comparative studies looking at the efficacy of the different cell types.

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.

Rotator Cuff Repair With Autologous Tenocytes and Biodegradable Collagen Scaffold: A Histological and Biomechanical Study in Sheep

BACKGROUND

Large rotator cuff tears still represent a challenging problem in orthopaedics. The use of tenocytes on biomaterials/scaffolds for the repair of large rotator cuff defects might be a promising approach in the field of tendon regeneration.

HYPOTHESIS

Cultivated autologous tenocytes seeded on a collagen scaffold lead to enhanced histological and biomechanical results after rotator cuff repair in a sheep model as compared with unseeded scaffolds in an acute setting.

STUDY DESIGN

Controlled laboratory study.

METHODS

At the tendon-bone junction of the infraspinatus tendon of the right foreleg of 24 sheep, a 3.5 × 1.5-cm tendon defect was created. Sheep were randomly allocated to group 1, a defect; group 2, where an unseeded collagen scaffold was implanted; or group 3, which received the implantation of a collagen scaffold seeded with autologous tenocytes. Twelve weeks postoperatively, tendon regeneration was examined histologically and biomechanically.

RESULTS

The histology of the neotendons of group 3 showed better fiber patterns, a higher production of proteoglycans, and an increased genesis of collagen III in contrast to groups 1 and 2. Immunostaining revealed less tissue dedifferentiation, a more structured cartilage layer, and homogeneous cartilage-bone transition in group 3 in comparison with groups 1 and 2. Biomechanically, the tensile strength of the reconstructed tendons in group 3 (mean load to failure, 2516 N; SD, 407.5 N) was approximately 84% that of the native tendons (mean load to failure, 2995 N; SD, 223.1 N) without statistical significance. A significant difference (P = .0095) was registered between group 1 (66.9% with a mean load to failure of 2004 N; SD, 273.8 N) and the native tendons, as well as between group 2 (69.7% with a mean load to failure of 2088 N; SD, 675.4 N) and the native tendons for mean ultimate tensile strength. In breaking stress, a significant difference (P = .0095) was seen between group 1 (mean breaking stress, 1335 N/mm²; SD, 182.7 N/mm²) and the native tendons, as well as between group 2 (breaking stress, 1392 N/mm²; SD, 450.2 N/mm²) and the native tendons (mean breaking stress, 1996 N/mm²; SD, 148.7 N/mm²). Again, there was no significant difference between group 3 (mean breaking stress, 1677 N/mm²; SD, 271.7 N/mm²) and the native tendons.

CONCLUSION

Autologous tenocytes seeded on collagen scaffolds yield enhanced biomechanical results after tendon-bone reconstruction as compared with unseeded scaffolds in an acute setting. Biomechanical results and histological outcomes were promising, showing that the use of autologous tenocytes with specific carrier matrices could be a novel approach for repairing rotator cuff tears.

CLINICAL RELEVANCE

This study supports the use of tenocytes and scaffolds for improving the quality of tendon-bone regeneration.

Spectrum of Tendon Pathologies: Triggers, Trails and End-State

The biggest compartment of the musculoskeletal system is the tendons and ligaments. In particular, tendons are dense tissues connecting muscle to bone that are critical for the integrity, function and locomotion of this system. Due to the increasing age of our society and the overall rise in engagement in extreme and overuse sports, there is a growing prevalence of tendinopathies. Despite the recent advances in tendon research and due to difficult early diagnosis, a multitude of risk factors and vague understanding of the underlying biological mechanisms involved in the progression of tendon injuries, the toolbox of treatment strategies remains limited and non-satisfactory. This review is designed to summarize the current knowledge of triggers, trails and end state of tendinopathies.

Efficacy of bone marrow stimulation in arthroscopic repair of full thickness rotator cuff tears: a meta-analysis

Background

To conduct a meta-analysis to compare the curative effect of treating the full thickness tear of the rotator cuff using the arthroscopic bone marrow stimulation (BMS) technology and provide the evidence for its extensive clinical application.

Methods

A systematic literature search was conducted to evaluate the studies on comparison of the curative effect of routine surgery with or without BMS on rotator cuff tear in the major medical databases. The literature was screened according to the inclusion and exclusion standards, and the quality assessment was conducted, then Review Manager 5.3 software was used for meta-analysis.

Results

Eight articles were eligible for inclusion. There were no statistically significant differences between BMS and control groups for overall outcome scores (P > 0.05). Except the Constant score of BMS group was significantly higher than that of the control group at the third follow-up month (P = 0.007). However, the postoperative re-tear rate of the BMS group was significantly lower than that of the control group (P < 0.001). Furthermore, we made a subgroup analysis and found that the postoperative Constant and UCLA score had no significant differences among all groups (P > 0.05), and the re-tear rates of the BMS groups were lower than those of the control groups (P = 0.001, P = 0.0002).

Conclusions

BMS technology has no significant influence on the postoperative clinical result of patients. However, it can obviously promote the tendon-to-bone healing of the rotator cuff and decrease the re-tear rate, which provides evidence for the clinical treatment.

Current concepts on tenogenic differentiation and clinical applications

Tendon is a tissue that transmits force from muscle to bone. Chronic or acute tendon injuries are very common, and are always accompanied by pain and a limited range of motion in patients. In clinical settings, management of tendon injuries still remains a big challenge. Cell therapies, such as the application of stem cells for tenogenic differentiation, were suggested to be an ideal strategy for clinical translation. However, there is still a lack of specific methods for tenogenic differentiation due to the limited understanding of tendon biology currently. This review focuses on the summary of current published strategies for tenogenic differentiation, such as the application of growth factors, mechanical stimulation, biomaterials, coculture, or induced pluripotent stem cells. Current clinical applications of stem cells for treatment of tendon injuries and their limitations have also been discussed in this review.

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

BACKGROUND

Gluteal tendinopathy is a common cause of lateral hip pain, and existing conservative treatment modalities demonstrate high symptom recurrence rates. Autologous tenocyte injection (ATI) is a promising cell therapy that may be useful for the treatment of gluteal tendinopathy.

PURPOSE

To investigate the safety and effectiveness of ATI, specifically in patients with chronic recalcitrant gluteal tendinopathy.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twelve female patients with a clinical and radiological diagnosis of gluteal tendinopathy were recruited. Patients demonstrated a mean duration of symptoms of 33 months (range, 6-144 months), had undergone a mean 3.2 prior corticosteroid injections (range, 2-5), and had failed to respond to existing conservative treatments including physiotherapy and injections. In an initial procedure, tendon cells were harvested from a needle biopsy of the patella tendon and propagated in a certified Good Manufacturing Practice (GMP) laboratory. In a secondary procedure, a single injection of 2 mL autologous tenocytes (2-5 × 106 cells/mL) suspended in patient serum was injected into the site of the pathological gluteal tendons under ultrasound guidance. Patients were assessed pre- and postinjection (3, 6, 12, and 24 months) using the Oxford Hip Score (OHS), a visual analog pain scale (VAS), the Short Form-36 (SF-36), and a satisfaction scale. Magnetic resonance imaging (MRI) was undertaken at 8.7 months (range, 6-12 months) postinjection.

RESULTS

Molecular characterization of autologous tendon cells showed a profile of growth factor production in all cases, including platelet-derived growth factor α, fibroblast growth factor β, and transforming growth factor β. The OHS (mean, 24.0 preinjection to 38.9 at 12 months [14.9-point improvement]; 95% CI, 10.6-19.2; P < .001), VAS (mean, 7.2 preinjection to 3.1 at 12 months [4.1-point improvement]; 95% CI, 2.6-5.6; P < .001), and SF-36 (mean, 28.1 preinjection to 43.3 at 12 months [15.2-point improvement]; 95% CI, 9.8-20.5; P < .001) significantly improved to 12 months postinjection, sustained to 24 months. Eight patients were satisfied with their outcomes. Significant MRI-based improvement could not be demonstrated in the majority of cases.

CONCLUSION

ATI for gluteal tendinopathy is safe, with improved and sustained clinical outcomes to 24 months.

Lateral Elbow Tendinopathy: Development of a Pathophysiology-Based Treatment Algorithm

Lateral elbow tendinopathy, commonly known as tennis elbow, is a condition that can cause significant functional impairment in working-age patients. The term tendinopathy is used to describe chronic overuse tendon disorders encompassing a group of pathologies, a spectrum of disease. This review details the pathophysiology of tendinopathy and tendon healing as an introduction for a system grading the severity of tendinopathy, with each of the 4 grades displaying distinct histopathological features. Currently, there are a large number of nonoperative treatments available for lateral elbow tendinopathy, with little guidance as to when and how to use them. In fact, an appraisal of the clinical trials, systematic reviews, and meta-analyses studying these treatment modalities reveals that no single treatment reliably achieves outstanding results. This may be due in part to the majority of clinical studies to date including all patients with chronic tendinopathy rather than attempting to categorize patients according to the severity of disease. We relate the pathophysiology of the different grades of tendinopathy to the basic science principles that underpin the mechanisms of action of the nonoperative treatments available to propose a treatment algorithm guiding the management of lateral elbow tendinopathy depending on severity. We believe that this system will be useful both in clinical practice and for the future investigation of the efficacy of treatments.

[Clinical management of rotator cuff tears. Current concepts in cell-based therapy strategies]

Due to the increasing demand for functionality in an aging yet physically active society, the treatment of rotator cuff tears is of ever-growing importance. Despite intensive research efforts, the treatment of degenerative rotator cuff tears, in particular their long-term outcome, is still a challenge. While in recent years the focus was on biomechanics and the technical aspects of rotator cuff reconstruction, attention has now turned to the biological considerations of tendon regeneration. This article highlights the current state of biological rotator cuff augmentation in a clinical setting and provides an insight into and an outlook on the experimental procedures.

Partial Thickness Rotator Cuff Tears: Current Concepts

Partial thickness rotator cuff tears are a common cause of pain in the adult shoulder. Despite their high prevalence, the diagnosis and treatment of partial thickness rotator cuff tears remains controversial. While recent studies have helped to elucidate the anatomy and natural history of disease progression, the optimal treatment, both nonoperative and operative, is unclear. Although the advent of arthroscopy has improved the accuracy of the diagnosis of partial thickness rotator cuff tears, the number of surgical techniques used to repair these tears has also increased. While multiple repair techniques have been described, there is currently no significant clinical evidence supporting more complex surgical techniques over standard rotator cuff repair. Further research is required to determine the clinical indications for surgical and nonsurgical management, when formal rotator cuff repair is specifically indicated and when biologic adjunctive therapy may be utilized.

Reliability of a 3 T MRI protocol for objective grading of supraspinatus tendonosis and partial thickness tears

BACKGROUND

Partial thickness supraspinatus tears and tendonosis can be managed either nonoperatively or by various arthroscopic techniques. New biologic treatment approaches are currently being investigated. MRI is commonly used for objective imaging outcome evaluation but there is a lack of reliability studies. We propose a novel MRI classification of partial supraspinatus tears and tendonosis and evaluate its inter-observer and intra-observer reliability.

METHODS

Digital MRI scans (3 Tesla) of 65 patients investigated for assessment of supraspinatus pathology or subacromial impingement were evaluated by three independent and experienced musculoskeletal (MSK) radiologists. Tendonosis (absent, focal, generalized), partial thickness (PT) tears (absent, 0%-25% PT, 25%-50% PT, 50%-100% PT, and full thickness tears), and anteroposterior extent of tears (less than 5 mm, 5-10 mm, greater than 10 mm) were scored by each radiologist on two separate occasions (t1, t2), 2 months apart. The inter-observer and intra-observer agreement and weighted kappa values for each parameter were calculated.

RESULTS

The range of weighted intra-observer kappa (IAK) was 0.84-0.93 for evaluation of tendonosis; 0.84 (all raters) for depth of partial thickness, 0.74-0.84 for AP tear size, and 0.83-0.85 for the total score. The range of weighted inter-observer kappa (IEK) over two time points (t1, t2) was 0.55-0.74 for tendonosis, 0.69-0.84 for depth for partial thickness tears, 0.57-0.80 for AP tear size, and 0.63-0.80 for the total score.

CONCLUSION

A comprehensive MRI grading protocol is proposed and is reliable for the evaluation of supraspinatus tendonosis and partial thickness tears with good to excellent kappa values. This rotator cuff MRI protocol can be applied to evaluate morphological tendon outcomes after different treatment modalities.

Autologous tenocyte injection for the treatment of severe, chronic resistant lateral epicondylitis: a pilot study

BACKGROUND

Severe chronic lateral epicondylitis (LE) is associated with degenerative tendon changes, extracellular matrix breakdown, and tendon cell loss. On the basis of positive outcomes from preclinical studies, this study is the first clinical trial of autologous tenocyte injection (ATI) on severe tendinopathy associated with chronic LE.

HYPOTHESIS

Autologous tenocyte injection is a safe and effective procedure that enables a reduction in pain and improvement in function in resistant LE.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with severe refractory LE underwent clinical evaluation and magnetic resonance imaging (MRI) before intervention. A patellar tendon needle biopsy was performed under local anesthetic, and tendon cells were expanded by in vitro culture. Tenocytes used for the injection were characterized by flow cytometry and real-time polymerase chain reaction. Autologous tenocytes were injected into the site of tendinopathy identified at the origin of the extensor carpi radialis brevis tendon under ultrasound guidance on a single occasion. Patients underwent serial clinical evaluations and repeat MRI at 12 months after intervention.

RESULTS

A total of 20 consecutive patients were included in the study. Three patients withdrew consent after enrollment and before ATI. No adverse event was reported at either biopsy or injection sites. Furthermore, no infection or excessive fibroblastic reaction was found in any patient at the injection site. Clinical evaluation revealed an improvement in mean visual analog scale scores, for a maximum pain score from 5.94 at the initial assessment to 0.76 at 12 months (P < .001). Mean quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) and grip strength scores also significantly improved over the 12-month follow-up (QuickDASH score, 45.88 [baseline] to 3.84; grip strength, 20.17 kg [baseline] to 37.38 kg; P < .001). With use of a validated MRI scoring system, the grade of tendinopathy at the common extensor origin improved significantly by 12 months (P < .001). One patient elected to proceed to surgery 3 months after ATI following a reinjury at work.

CONCLUSION

In this study, patients with chronic LE who had previously undergone an unsuccessful full course of nonoperative treatment showed significantly improved clinical function and structural repair at the origin of the common extensor tendon after ATI. This novel treatment is encouraging for the treatment of tendinopathy and warrants further evaluation.

Tissue-engineered augmentation of a rotator cuff tendon using a reconstituted collagen scaffold: a histological evaluation in sheep

To determine if an absorbable collagen scaffold of high porosity would allow rapid tissue in-growth and permit the functional maturation and alignment of tendon-like tissue, scaffolds were sutured to the superficial surface of the infraspinatus tendons of adult sheep. Histology demonstrated complete ingrowth with fibrovascular tissue by 6 weeks and by 12 weeks the scaffold had induced the formation of a layer of dense, regularly-oriented collagenous tissue which significantly increased the thickness of the native tendon. This new tissue was well-integrated into the host tissues at both the bone interface and along the length of the tendon. At 26 weeks the scaffold was completely absorbed leaving a stable layer of mature tendon-like tissue over the surface of the host tendon which was still present at 52 weeks. The use of a reconstituted collagen scaffold consistently increased the thickness of a rotator cuff tendon by inducing the formation of a well-integrated and mature tendon-like tissue.