Similar effects of recombinant human insulin-like growth factor-I and II on cellular activities in flexor tendons of young rabbits: experimental studies in vitro

High-intensity interval training enhances mRNA expression of IGF1Ea in rat Achilles tendon

High-intensity interval training (HIIT) reportedly enhances the functional properties of the musculoskeletal system. However, the effects of HIIT on tendons remain unclear. Sixteen male rats were randomly assigned to the control (Con) or HIIT group (n = 8 in each group). Rats in the HIIT group executed the HIIT program consisting of 2.5 min treadmill running and 4.5 min rests between the bouts, 5 days per week for 9 weeks. Running speed, number of sets, and inclination were incrementally increased during the training period. Histological analysis revealed no apparent morphological changes in the extracellular matrix structure or nuclei of tenocytes between the groups. Real-time reverse transcription polymerase chain reaction analysis revealed that Igf1Ea mRNA expression was enhanced in the HIIT group. Furthermore, Igfbp5 mRNA expression tended to be higher in the HIIT group. The 9-week HIIT program enhanced tenogenic Igf1Ea mRNA expression.

Current progress in growth factors and extracellular vesicles in tendon healing

Tendon injury healing is a complex process that involves the participation of a significant number of molecules and cells, including growth factors molecules in a key role. Numerous studies have demonstrated the function of growth factors in tendon healing, and the recent emergence of EV has also provided a new visual field for promoting tendon healing. This review examines the tendon structure, growth, and development, as well as the physiological process of its healing after injury. The review assesses the role of six substances in tendon healing: insulin-like growth factor-I (IGF-I), transforming growth factor β (TGFβ), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and EV. Different growth factors are active at various stages of healing and exhibit separate physiological activities. IGF-1 is expressed immediately after injury and stimulates the mitosis of various cells while suppressing the response to inflammation. VEGF, which is also active immediately after injury, accelerates local metabolism by promoting vascular network formation and positively impacts the activities of other growth factors. However, VEGF's protracted action could be harmful to tendon healing. PDGF, the earliest discovered cytokine to influence tendon healing, has a powerful cell chemotaxis and promotes cell proliferation, but it can equally accelerate the response to inflammation and relieve local adhesions. Also useful for relieving tendon adhesion is TGF- β, which is active almost during the entire phase of tendon healing. As a powerful active substance, in addition to its participation in the field of cardiovascular and cerebrovascular vessels, tumour and chronic wounds, TGF- β reportedly plays a role in promoting cell proliferation, activating growth factors, and inhibiting inflammatory response during tendon healing.

Comparative effects of radial and focused extracorporeal shock wave therapies in coccydynia

Objectives

This study was conducted to compare the effects of radial and focused extracorporeal shock wave therapy (ESWT) in patients with coccydynia.

Patients and methods

In this prospective randomized double-blind study conducted between March 2021 and October 2021, 60 patients with coccydynia (50 males, 10 females; mean age: 35.9±12.0 years, range 18 to 65 years) were randomized into three groups (n=20) according to different wave types of ESWT: focused, radial, and sham. The Visual Analog Scale (VAS) was used for pain assessment, and the Oswestry Disability Index (ODI) was used for functional assessment in all patients before the treatment (baseline), after the completion of four sessions of treatment (fourth week), one month after the end of the treatment (eighth week), and three months after the end of the treatment (16^th week).

Results

The mean body mass index of the participants was 26.2±3.0. Compared to baseline, the VAS scores at four weeks were reduced only in the radial ESWT group (p<0.05). Compared to baseline, the VAS and ODI scores at eight and 16 weeks were significantly reduced in both the focused and radial ESWT groups (p<0.05 for all). The radial ESWT group was significantly superior to the focused ESWT group in the comparisons between the groups at four weeks in the VAS values and at 16 weeks in the ODI scores (p<0.05 for all).

Conclusion

Radial and focused ESWT are both effective in treating coccydynia compared to sham ESWT. However, radial ESWT may be more effective in the treatment of coccydynia.

Biomechanically and biochemically functional scaffold for recruitment of endogenous stem cells to promote tendon regeneration

Tendon regeneration highly relies on biomechanical and biochemical cues in the repair microenvironment. Herein, we combined the decellularized bovine tendon sheet (DBTS) with extracellular matrix (ECM) from tendon-derived stem cells (TDSCs) to fabricate a biomechanically and biochemically functional scaffold (tECM-DBTS), to provide a functional and stem cell ECM-based microenvironment for tendon regeneration. Our prior study showed that DBTS was biomechanically suitable to tendon repair. In this study, the biological function of tECM-DBTS was examined in vitro, and the efficiency of the scaffold for Achilles tendon repair was evaluated using immunofluorescence staining, histological staining, stem cell tracking, biomechanical and functional analyses. It was found that tECM-DBTS increased the content of bioactive factors and had a better performance for the proliferation, migration and tenogenic differentiation of bone marrow-derived stem cells (BMSCs) than DBTS. Furthermore, our results demonstrated that tECM-DBTS promoted tendon regeneration and improved the biomechanical properties of regenerated Achilles tendons in rats by recruiting endogenous stem cells and participating in the functionalization of these stem cells. As a whole, the results of this study demonstrated that the tECM-DBTS can provide a bionic microenvironment for recruiting endogenous stem cells and facilitating in situ regeneration of tendons.

Physiological Parameters to Identify Suitable Blood Donor Cows for Preparation of Platelet Rich Plasma

Simple Summary

Platelet rich plasma is a biological product obtained from blood and used for regenerative treatments of different pathologies. It is characterized by a high concentration of platelets (at least 3 times the physiological level) containing many growth factors with anti-inflammatory, bactericidal and regenerative properties. In human medicine, PRP is used in an autologous way, it means that the blood donor is also the recipient. In veterinary medicine, PRP is used to treat different diseases or lesions and in bovine species to treat mastitis. In this context, the opportunity to have PRP ready to use, stored from donor cows of the same farm where it will be used, would be very useful in treating this pathology immediately when it occurs. For this purpose, the present research aimed to detect parameters useful to identify the most suitable cows to be used as blood donors to obtain the highest yield of PRP (milliliters of PRP obtained with respect to milliliters of initial blood). Our results showed that blood collection from the mammary vein within three months of parturition, from nonpregnant cows at 5 years of age, but not the blood collection season, were associated with a high yield of PRP.

Abstract

Platelet rich plasma (PRP) has been shown to be beneficial in the treatment of bovine mastitis, with an action comparable to that of antibiotics. Autologous treatment is feasible in experimental conditions but is difficult to apply in field conditions, particularly in acute mastitis. The ideal scenario would be to have heterologous PRP stored on every farm so that it is readily available when needed. In this paper, we analysed data collected during bovine mastitis treatment with heterologous PRP produced by casual donor cows on several farms. We tried to identify parameters which might be useful to identify the most suitable cows to be used as blood donors, to obtain the highest yield of PRP. Variables considered for each animal were the age, the parity, the date of the last parturition, the season of blood collection, the site of blood collection (jugular or mammary vein) and the reproductive status e.g., pregnant or not pregnant. There were statistically significant differences for all the variables considered from the 135 blood cows, except for the blood collection season. The highest yield of PRP was associated with nonpregnancy blood collection within three months of parturition, parity 3 or 4, and blood collection from the mammary vein.

The Effect of Insulin and Insulin-like Growth Factor 1 (IGF-1) on Cellular Proliferation and Migration of Human Subacromial Bursa Tissue

Purpose

To evaluate the effect of a one-time dose of insulin or insulin-like growth factor 1 (IGF-1) on cellular proliferation and migration of subacromial bursa tissue (SBT) over time.

Methods

SBT was harvested from over the rotator cuff tendon in 4 consecutive patients undergoing primary arthroscopic rotator cuff repair. SBT was cultured for 3 weeks in complete media until reaching confluence. The culture dishes were stored in a humidified, low oxygen tension (5% CO₂) incubator at 37°C. SBT of each patient underwent treatment with a one-time dose of insulin or IGF-1, whereas nontreated SBT served as a negative control. Cellular proliferation and migration were evaluated after 24, 48, 72, and 96 hours of incubation. SBT-derived cells migrated in the detection field were visualized using fluorescent microscopy.

Results

Cellular proliferation at 24, 48, 72, and 96 hours was 1.40 ± 0.27, 1.00 ± 0.20, 1.47 ± 0.31, and 1.68 ± 0.28 for IGF-1; 1.44 ± 0.24, 1.15 ± 0.27, 1.60 ± 0.36, and 1.61 ± 0.32 for insulin; and 1.51 ± 0.35, 1.29 ± 0.33, 1.53 ± 0.35, and 1.57 ± 0.38 for nontreated SBT. Untreated SBT demonstrated a significantly greater proliferation when compared with IGF-1 and insulin within the first 48 hours, although this effect was found to subside by 96 hours. Cellular migration at 24, 48, 72, and 96 hours was 575.7 ± 45.0, 641.6 ± 77.7, 728.3 ± 122.9, and 752.3 ± 114.5 for IGF-1; 528.4 ± 31.3, 592.5 ± 69.8, 664.2 ± 115.2, and 695.6 ± 148.2 for insulin; and 524.4 ± 41.9, 564.4 ± 49.8, 653.2 ± 81.5, and 685.7 ± 115.5 for nontreated SBT. Insulin showed no difference in migration at each timepoint compared to nontreated SBT (P > .05, respectively).

Conclusions

Insulin and IGF-1 initially inhibit cellular proliferation of human SBT, although this effect was found to subside by 96 hours. Further, neither insulin nor IGF-1 changed the slope of cellular migration over time. However, each treatment group demonstrated a significant increase in cellular proliferation and migration.

Clinical Relevance

In the setting of biologic augmentation of rotator cuff repair, the compatibility and synergistic effect of insulin on human SBT is highly limited.

Effectiveness of Amniotic Fluid Injection in the Treatment of Trigger Finger: A Pilot Study

Purpose

To assess the efficacy and safety of amniotic fluid therapy injections in patients with mild to moderate trigger finger.

Methods

All participants received 1 mL of amniotic fluid injected into the tendon sheath of the affected tendon. Pretreatment and posttreatment data were collected for triggering frequency, Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores, and numerical pain rating scale scores.

Results

Of 111 digits from 96 patients, 51% experienced clinically notable improvement and did not receive an alternative treatment. Average length of follow-up was 11 months. From baseline to end of follow-up, average pain score (0–10) decreased from 5.19 to 1.19 (P < .001), median triggering per day decreased from 5 to 0 (P < .001), and median DASH score (1–100) decreased from 20 to 6.03 (P < .001). There was a 50% success rate in patients with diabetes and a 52.6% success rate in digits diagnosed with concomitant Dupuytren contracture in the same hand.

Conclusions

Amniotic fluid therapy injections may offer a biologic alternative for conservative treatment of trigger finger, particularly for patients with diabetes. Decreased pain, decreased triggering, and improved DASH scores offer preliminary evidence supporting the use of amniotic injections for stenosing tenosynovitis.

Type of study/level of evidence

Therapeutic IV.

Tendon and Ligament Healing and Current Approaches to Tendon and Ligament Regeneration

Ligament and tendon injuries are common problems in orthopedics. There is a need for treatments that can expedite nonoperative healing or improve the efficacy of surgical repair or reconstruction of ligaments and tendons. Successful biologically-based attempts at repair and reconstruction would require a thorough understanding of normal tendon and ligament healing. The inflammatory, proliferative, and remodeling phases, and the cells involved in tendon and ligament healing will be reviewed. Then, current research efforts focusing on biologically-based treatments of ligament and tendon injuries will be summarized, with a focus on stem cells endogenous to tendons and ligaments. Statement of clinical significance: This paper details mechanisms of ligament and tendon healing, as well as attempts to apply stem cells to ligament and tendon healing. Understanding of these topics could lead to more efficacious therapies to treat ligament and tendon injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:7-12, 2020.

The Efficacy of Extracorporeal Shock Wave Therapy for Chronic Coccydynia

OBJECTIVE

Coccydynia is a disorder that decreases quality of life with significant functional failure. Extra-corporeal shock wave therapy (ESWT) is used to treat several painful musculoskeletal disorders.

SUBJECTS AND METHODS

The medical records of 34 patients (29 females, 5 males) who had been treated with ESWT between 2017 and 2018 for chronic coccydynia were evaluated. Visual analog scale (VAS) scores were noted at the initial consultation, at each session, and during the initial and follow-up (at 6 months) examinations after the treatment. The 36-item short form (SF-36) quality of life scale survey was conducted at the beginning and end of the treatment. MRI was performed before the start of the procedure and 1 month after the end of the treatment.

RESULTS

The mean VAS score was 9.6 (9-10) before the treatment and 3.4 (0-2) after the treatment (p < 0.05). The VAS score decreased to ≤3 in 79.4% of patients. Bone marrow edema regressed in 6% of patients. Significant improvement was observed in all of the SF-36 parameters, except for two.

CONCLUSION

In our patient group, ESWT provided effective pain control. In order to evaluate the efficacy of ESWT more accurately and sensitively, prospective randomized studies with longer follow-up periods, in which ESWT is compared with different energy doses and different treatment methods, are needed.

Comparative Effectiveness of Different Nonsurgical Treatments for Patellar Tendinopathy: A Systematic Review and Network Meta-analysis

PURPOSE

To investigate the functional improvement and pain reduction of different nonsurgical treatments for patellar tendinopathy (PT), a systematic review with network meta-analysis was performed.

METHODS

Studies were comprehensively searched for without language restrictions in the CENTRAL, MEDLINE, EMBASE, Web of Science, Physiotherapy Evidence Database, and SPORTDiscus databases from inception to May 2018. Randomized controlled trials about nonsurgical treatments for PT were included. The outcome measurements were the Victorian Institute of Sports Assessment (VISA) scale and pain scores (such as the visual analog scale or Numerical Rating Scale). Study quality was evaluated using the Physiotherapy Evidence Database score. Direct comparisons were performed using pairwise meta-analysis, whereas network meta-analysis was performed using a frequentist method in a multivariate random-effects model.

RESULTS

Eleven studies with 430 affected patellar tendons were included in the systematic review. The summary mean difference of improvement in the VISA scale versus the control group for corticosteroid injection was -23.00 (95% confidence interval [CI] -36.73 to -9.27), for leukocyte-rich platelet-rich plasma (LR-PRP) was 13.22 (95% CI 2.37-24.07), for focused extracorporeal shockwave therapy (ESWT) was -1.28 (95% CI -6.25 to 3.68), for radial ESWT was -6.68 (95% CI -20.20 to 6.84), for ultrasound was -0.70 (95% CI -11.23 to 9.83), for autologous blood injection was -0.60 (95% CI -9.30 to 8.10), for dry needling was 17.51 (95% CI -2.57 to 37.60), for topical glyceryl trinitrate was -0.90 (95% CI -13.07 to 11.27), and for skin-derived tendon-like cells was 10.40 (95% CI -1.59 to 22.39). LR-PRP (Surface Under the Cumulative Ranking curve [SUCRA] = 87.5%) or dry needling (SUCRA = 90.5%) was most likely to be ranked the best in terms of improvement on the VISA scale. Compared with the control group, the summary mean difference of the change in pain score for corticosteroid injection was 0.80 (95% CI -3.48 to 5.08), for LR-PRP was -1.87 (95% CI -3.28 to -0.46), for focused ESWT was 0.13 (95% CI -0.68 to 0.93), for radial ESWT was 0.03 (95% CI -1.92 to 1.98), for ultrasound was -0.20 (95% CI -1.49 to 1.09), for autologous blood injection was 0.60 (95% CI -0.73 to 1.93), for dry needling was -0.37 (95% CI -2.71 to 1.97), and for topical glyceryl trinitrate was -0.50 (95% CI -2.55 to 1.55). The treatment most likely to be ranked the best in terms of change in pain score was LR-PRP (SUCRA = 94.9%).

CONCLUSIONS

The network meta-analysis demonstrated that LR-PRP has the greatest functional improvement and pain reduction for PT compared with other treatment options. However, the treatment effect estimates can be biased by the possible intransitivity and should not be overestimated.

LEVEL OF EVIDENCE

Level I, meta-analysis of Level I studies.

Evaluation of Blood Clot, Platelet-rich Plasma, Platelet-rich Fibrin, and Platelet Pellet as Scaffolds in Regenerative Endodontic Treatment: A Prospective Randomized Trial

INTRODUCTION

Regenerative endodontic procedures (REPs) using autologous platelet concentrates as scaffolds can improve the biologic outcome of treatment. This prospective, randomized trial compared the clinical and radiographic performance of REPs using platelet-rich plasma (PRP), platelet-rich fibrin (PRF), a platelet pellet (PP), and an induced blot clot (BC).

METHODS

Sixty-seven healthy children (aged 8-11 years) with 88 immature necrotic incisors were included. After the root canal disinfection step, the teeth were randomly assigned into 1 of the following groups (n = 22/group) according to the scaffold used: PRP, PRF, PP, and BC. In the PRP, PRF, and PP groups, the platelet concentrates were introduced into the root canal without prior induction of apical bleeding. Treatment outcomes were assessed using a combined clinical and radiographic scoring system, whereas the changes in root dimensions were compared using linear measurements of root length and width with ImageJ (National Institutes of Health, Bethesda, MD) and Turboreg (Biomedical Imaging Group, Swiss Federal Institute of Technology, Lausanne, Switzerland) and planar measurements using the radiographic root area (RRA) and radiographic canal area (RCA) techniques. One-way analysis of variance, the Duncan multiple range test, the Kruskal-Wallis test, the Mann-Whitney U test, and chi-square dependency tests were used for statistical analysis of data (all P = .05).

RESULTS

Except for 2 teeth in the PRF and BC groups, all teeth showed similar and high success scores (periapical healing, radiographic root development, and positive response to sensitivity tests) after an average follow-up time of 28.25 ± 1.2 months. Of all teeth, 73.9% showed complete apical closure with similar closure rates among groups (P > .05) and a greater tendency for conical-shaped apical closure than a blunt apex. Although linear measurements indicated a similar increase in root length and width among all groups (P > .05), the RRA of the BC group was significantly greater than those of the PRF and PP groups, and the RCA of the BC group was significantly greater than PRP, PRF, and PP (all P < .05) when the follow-up time was not used as a factor. Eighty-six percent of the teeth showed a positive response to sensitivity tests with similar initial response times (P > .05).

CONCLUSIONS

PRP, PRF, and PP can yield similar clinical and radiographic outcomes to BC without the need for prior apical bleeding and with significantly less tendency for root canal obliteration. RRA and RCA may reveal minor differences that cannot be determined by linear measurements.

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.

Activation of AKT-mTOR Signaling Directs Tenogenesis of Mesenchymal Stem Cells

Tendon repair is a clinical challenge because of the limited understanding on tenogenesis. The synthesis of type I collagen (Collagen I) and other extracellular matrix are essential for tendon differentiation and homeostasis. Current studies on tenogenesis focused mostly on the tenogenic transcriptional factors while the signaling controlling tenogenesis on translational level remains largely unknown. Here, we showed that mechanistic target of rapamycin (mTOR) signaling was activated by protenogenic growth factor, transforming growth factors beta1, and insulin-like growth factor-I. The expression of mTOR was upregulated during tenogenesis of mesenchymal stem cells (MSCs). Moreover, mTOR was downregulated in human tendinopathy tissues and was inactivated upon statin treatment. Both inhibition and depletion of AKT or mTOR significantly reduced type I collagen production and impaired tenogenesis of MSCs. Tendon specific-ablation of mTOR resulted in tendon defect and reduction of Collagen I. However, there is no evident downregulation of tendon associated collagens at the transcription level. Our study demonstrated that AKT-mTOR axis is a key mediator of tendon differentiation and provided a novel therapeutic target for tendinopathy and tendon injuries. Stem Cells 2018;36:527-539.

Next Generation Tissue Engineering of Orthopedic Soft Tissue-to-Bone Interfaces

Soft tissue-to-bone interfaces are complex structures that consist of gradients of extracellular matrix materials, cell phenotypes, and biochemical signals. These interfaces, called entheses for ligaments, tendons, and the meniscus, are crucial to joint function, transferring mechanical loads and stabilizing orthopedic joints. When injuries occur to connected soft tissue, the enthesis must be re-established to restore function, but due to structural complexity, repair has proven challenging. Tissue engineering offers a promising solution for regenerating these tissues. This prospective review discusses methodologies for tissue engineering the enthesis, outlined in three key design inputs: materials processing methods, cellular contributions, and biochemical factors.

Therapeutics for tendon regeneration: a multidisciplinary review of tendon research for improved healing

Tendon injuries, known as tendinopathies, are common musculoskeletal injuries that affect a wide range of the population. Canonical tendon healing is characterized by fibrosis, scar formation, and the loss of tissue mechanical and structural properties. Understanding the regenerative tendon environment is an area of increasing interest in the field of musculoskeletal research. Previous studies have focused on utilizing individual elements from the fields of biomechanics, developmental biology, cell and growth factor therapy, and tissue engineering in an attempt to develop regenerative tendon therapeutics. Still, the specific mechanism for regenerative healing remains unknown. In this review, we highlight some of the current approaches of tendon therapeutics and elucidate the differences along the tendon midsubstance and enthesis, exhibiting the necessity of location-specific tendon therapeutics. Furthermore, we emphasize the necessity of further interdisciplinary research in order to reach the desired goal of fully understanding the mechanisms underlying regenerative healing.

Extracorporeal shockwave therapy (ESWT) for refractory Achilles tendinopathy: A prospective audit with 2-year follow up

BACKGROUND

Achilles tendinopathy (AT) represents a triad of tendon pain, swelling and impaired performance. Extracorporeal shockwave therapy (ESWT) has been endorsed by the National Institute for Health and Care Excellence (NICE) for refractory AT. This audit investigates the long-term outcomes of patients treated with ESWT for refractory AT.

METHODS

Forty-six patients treated with ESWT for AT between October 2010 and August 2011 completed visual analogue, satisfaction scores and functional assessment questionnaires over two years. Patients were subdivided into two groups depending on whether their AT was insertional (IAT) or non-insertional (NAT).

RESULTS

Forty-six patients (mean age 58 years) completed all treatments and full 2 year follow up. There was significant improvement in pain at rest, on activity and of function within both NAT and IAT groups over the two-year period. Satisfaction scores were significant in the NAT group but not in the IAT group.

CONCLUSIONS

ESWT appears to be of benefit in the long term improvement of pain at rest, on activity and functional outcome in patients with refractory AT. However, subjective patient opinion may not match the perceived clinical outcome observed in this audit in all patients and individuals should be counselled regarding this prior to treatment.

The Effects of Extracorporeal Shock Wave Therapy in Patients with Coccydynia: A Randomized Controlled Trial

Coccydynia is pain in the coccygeal region, and usually treated conservatively. Extracorporeal shock wave therapy (ESWT) was incorporated as non-invasive treatment of many musculoskeletal conditions. However, the effects of ESWT on coccydynia are less discussed. The purpose of this study is to evaluate the effects of ESWT on the outcomes of coccydynia. Patients were allocated to ESWT (n = 20) or physical modality (SIT) group (n = 21) randomly, and received total treatment duration of 4 weeks. The visual analog scale (VAS), Oswestry disability index (ODI), and self-reported satisfaction score were used to assess treatment effects. The VAS and ODI scores were significantly decreased after treatment in both groups, and the decrease in the VAS score was significantly greater in the ESWT group. The mean proportional changes in the ODI scores were greater in the ESWT group than in the SIT group, but the between-group difference was not statistically significant. The patients in the ESWT group had significantly higher subjective satisfaction scores than SIT group. We concluded that ESWT is more effective and satisfactory in reducing discomfort and disability caused by coccydynia than the use of physical modalities. Thus, ESWT is recommended as an alternative treatment option for patients with coccydynia.

Biologics for tendon repair

Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management.

A comparative evaluation of the blood clot, platelet-rich plasma, and platelet-rich fibrin in regeneration of necrotic immature permanent teeth: A clinical study

INTRODUCTION

This study was designed as a clinical trial to evaluate and compare the regenerative potential of platelet-rich fibrin (PRF), platelet-rich plasma (PRP), and blood clot in immature necrotic permanent teeth with or without associated apical periodontitis.

METHODS

Access preparation was done under rubber dam isolation. Copious irrigation was done with 2.5% NaOCl and triple antibiotic paste was placed as an intracanal medicament. After 4 weeks, the cases were divided into four groups with five patients in each group. The study design had three test arms and one control arm. Group I in which mineral trioxide aggregate apexification was carried out and it was kept as control group to evaluate the regenerative potential of blood clot and platelet concentrates, Group II in which blood clot was used as scaffold in the canal, Group III in PRF was used as scaffold, and Group IV in which PRP carried on collagen was used as a scaffold.

RESULTS

The clinical and radiographic evaluation after 6 and 18 months was done by two independent observers who were blinded from the groups. The scoring was done as: None score was denoted by, Fair by 1, Good by 2, and Excellent by 3. The data were then analyzed statistically by Fisher's exact test using Statistics and Data 11.1(PRP Using harvest Smart PReP2) which showed statistically significant values in Group III as compared to other Groups.

CONCLUSION

PRF has huge potential to accelerate the growth characteristics in immature necrotic permanent teeth as compared to PRP and blood clot.

Treatment of tendinopathies with platelet-rich plasma

Pain and dysfunction related to tendinopathy are often refractory to traditional treatments and offer a unique challenge to physicians, because no gold standard treatment exists. Injectable biologics may represent a new modality in conjunction with a multifaceted treatment approach. Platelet-rich plasma (PRP) injections are not associated with the systemic or tendon degradation risks of corticosteroids or the inherent risks of surgery. Studies are promising but have not been replicated with high-powered evidence at the clinical level. Further evidence to expand understanding of the role of PRP in the treatment of tendinopathy is needed.

Intramammary administration of platelet concentrate as an unconventional therapy in bovine mastitis: first clinical application

Bovine udder infections induce a variety of changes in gene expression of different growth factors that may suggest their possible role in glandular tissue protection or repair processes. Growth factors and also chemokines and cytokines may act synergistically to increase the infiltration of neutrophils and macrophages to promote angiogenesis, fibroplasia, matrix deposition, and, ultimately, re-epithelialization. Considering the vast applications, typically in human medicine, of platelet concentrate (PC) and its ease of preparation, the aim of our study was to evaluate an alternative therapy to stimulate the regeneration of glandular tissue, administering a concentration in excess of the growth factors contained in the PC. In each one of the 3 farms examined in the trial, PC was prepared from donor cows in good health, free from infections, and with no records of medications administered during the previous 2 mo. The platelet produced in one farm was used only for treating the cows of the same farm in a heterologous way. A total of 229 mastitic quarters were divided in 3 groups: antibiotic group (treated with intramammary antibiotic), antibiotic and PC group (treated intramammarily with antibiotics in association with PC), and PC group (treated with intramammary PC alone). The diagnosis of mastitis was based on somatic cell count and bacteriological evaluation of the milk from the affected quarter. Platelet concentrate, alone or in association with antibiotic, was used for 3 consecutive days as an unconventional therapy in bovine acute and chronic mastitis. Our data show that the associated action of antibiotic and PC performed significantly better than the antibiotic alone, either for the recovery of the affected mammary quarters or for somatic cell count reduction. In the same way, the association antibiotic plus PC showed significantly fewer relapses compared with the antibiotic alone, either for acute or chronic mastitis. The treatment with only PC did not show statistically significant differences compared with both antibiotic alone or associated treatment for acute mastitis, and it was better than the use of only antibiotic for chronic mastitis. Our results show that PC alone may be useful for a quick resolution of the inflammatory response, playing a role in limiting the tissue damage to the mammary gland parenchyma and reducing the recurrence rates.

Tendon and ligament regeneration and repair: clinical relevance and developmental paradigm

As dense connective tissues connecting bone to muscle and bone to bone, respectively, tendon and ligament (T/L) arise from the somitic mesoderm, originating in a recently discovered somitic compartment, the syndetome. Inductive signals from the adjacent sclerotome and myotome upregulate expression of Scleraxis, a key transcription factor for tenogenic and ligamentogenic differentiation. Understanding T/L development is critical to establishing a knowledge base for improving the healing and repair of T/L injuries, a high-burden disease due to the intrinsically poor natural healing response. Current treatment of the three most common tendon injuries-tearing of the rotator cuff of the shoulder, flexor tendon of the hand, and Achilles tendon-include mostly surgical repair and/or conservative approaches, including biophysical modalities such as rehabilitation and cryotherapy. Unfortunately, the fibrovascular scar formed during healing possesses inferior mechanical and biochemical properties, resulting in compromised tissue functionality. Regenerative approaches have sought to augment the injured tissue with cells, scaffolds, bioactive agents, and mechanical stimulation to improve the natural healing response. The key challenges in restoring full T/L function following injury include optimal combination of these biological agents as well as their delivery to the injury site. A greater understanding of the molecular mechanisms involved in T/L development and natural healing, coupled with the capability of producing complex biomaterials to deliver multiple biofactors with high spatiotemporal resolution and specificity, should lead to regenerative procedures that more closely recapitulate T/L morphogenesis, thereby offering future patients the prospect of T/L regeneration, as opposed to simple tissue repair.

The growth factors involved in flexor tendon repair and adhesion formation

Flexor tendon injuries remain a significant clinical problem, owing to the formation of adhesions or tendon rupture. A number of strategies have been tried to improve outcomes, but as yet none are routinely used in clinical practice. Understanding the role that growth factors play in tendon repair should enable a more targeted approach to be developed to improve the results of flexor tendon repair. This review describes the main growth factors in tendon wound healing, and the role they play in both repair and adhesion formation.

Bilateral quadriceps rupture: results with and without platelet-rich plasma

This article presents a 46-year-old man with bilateral atraumatic quadriceps rupture that occurred while he was descending stairs. The patient underwent surgery the day after the accident. In the left knee, quadriceps reinsertion was performed using a conventional technique. In the right knee, platelet-rich plasma (PRP), both in its liquid and semisolid patterns, was added intraoperatively. Ultrasonography and magnetic resonance imaging evaluations were performed 1, 6, and 24 months postoperatively. At 6 and 24 months postoperatively, clinical and functional evaluations also were performed. Clinical examination showed no differences between the knees, and functional scores were the same for both knees. Ultrasonographic evaluation showed bilateral persistent tendon thickening and gross echotexture abnormalities, with no side-to-side differences. Magnetic resonance imaging showed signals of vascularized granulation tissue in both knees, which was more evident in the right (PRP) knee at 1 month postoperatively, along with a better signal of scar tissue in the right knee at 6 and 24 months postoperatively. The use of PRP yielded no better clinical or functional results than the lack of its use. However, a more intense and significant reparative healing process occurred where the PRP was used, thus suggesting a more rapid completion of the healing process, although this effect seems to remain only a radiographic finding with no clinical correlation.

Platelet-rich fibrin-mediated revitalization of immature necrotic tooth

Contemporary studies have shown that the regeneration of tissues and root elongation is possible in necrotic immature permanent teeth. The purpose of this case report is to add a new vista in regenerative endodontic therapy by using platelet rich fibrin for revitalization of immature non vital tooth. An 11year old boy with the history of trauma was diagnosed with the pulpal necrosis and symptomatic apical periodontitis in tooth #21. Intra oral periapical radiograph showed open apex and associated immature supernumerary tooth with respect to tooth #21. Access preparation and minimal instrumentation was done to remove necrotic debris under copious irrigation with 2.5% sodium hypochlorite. Triple antibiotic paste was packed in the canal for four weeks. During second visit, 5 mL of whole blood was drawn from the medial cubital vein of the patient and blood was then subjected to centrifugation at 2400 rpm for 12 minutes for the preparation of Platelet rich fibrin (PRF) utilizing Choukroun's method. Triple antibiotic paste was removed and canal was dried. PRF clot was pushed to the apical region of tooth #21 using hand pluggers. Three milimetres of Mineral trioxide (MTA) was placed in cervical part of the root canal and permanent restoration was done three days later. Clinical examination at 6 and 12 months revealed no sensitivity to percussion and palpation in tooth #21and it responded positively to both electric pulp and cold tests. Radiographic examination showed resolution of periapical rarefaction, further root development and apical closure of the tooth #21 and its associated supernumerary tooth. On the basis of successful outcome of the present case it can be stated that PRF clot may serve as a scaffold for regeneration of necrotic immature teeth.

The magnitude and character of resistance-training-induced increase in tendon stiffness at old age is gender specific

Human tendon mechanical properties are modified with loading. Moreover, there are indications that the training response in the tendon is gender specific. The aim of the current study was to examine whether in vivo patella tendon stiffness (K) differentially alters with training in older males compared with females. We also aimed to identify which endocrine pathway underlies the responses. Maximal knee extensor forces were also monitored to determine the training effect on muscle function. Fourteen healthy, habitually active older persons (seven males aged 74.0 ± 1.2 years (mean±SEM) and seven females aged 76.7 ± 1.2 years) were tested at baseline and after 12 weeks of weekly, progressive resistance training. With training, percentage increase in quadriceps maximum voluntary isometric force (MVC) was similar in males (2,469.6 ± 168.0 to 3,097.3 ± 261.9 N; +25.3 ± 6.1% (p < 0.01)) and females (1,728.8 ± 136.3 to 2,166.5 ± 135.8 N; +30.4 ± 15.1% (p < 0.05)), respectively. K increased more in males (338.0 ± 26.6 to 616.9 ± 58.7 N/mm; 79.8 ± 4.2% (p < 0.001)) compared to females (338.9 ± 31.0 to 373.2 ± 25.8 N/mm; +13.0 ± 3.7% (p < 0.001)). Interestingly, a pattern was found whereby below ~40% MVC, the females showed their greatest degree of K changes, whereas the males showed their greatest degree of K change above this relative force level. This gender contrast was also true at a standardised force level (1,200 N), with 5.8 ± 0.4% vs. 82.5 ± 1.8% increments in the females (i.e. value change from 380.3 ± 14.1 to 402.4 ± 13.3 N/mm) and the males (i.e. value change from 317.8 ± 13.8 to 580.2 ± 30.9 N/mm), respectively (p < 0.001). While circulating levels of both IGF-I and IL-6 did not alter with training, IGFBP-3 showed a significant training effect (19.1 ± 4.8%, p < 0.001) and only in the male sub-group (p = 0.038). We show here that with training, in vivo older females' tendon is less dramatically modulated than that of males'. We also show that the relative forces, at which the greatest adaptations are exhibited, differ by gender, with a suggestion of endocrine adaptations in males only. We thus propose that both training and rehabilitation regimens should consider gender-specific tendon responsiveness, at least in older persons.

Bone marrow-derived mesenchymal stem cells obtained during arthroscopic rotator cuff repair surgery show potential for tendon cell differentiation after treatment with insulin

PURPOSE

The purpose of this study was to determine whether a one-time physiologic dose of insulin when compared with the growth factors insulin-like growth factor 1, β-fibroblastic growth factor, and growth differentiation factor 5 is capable of differentiating bone marrow-derived mesenchymal stem cells (MSCs) into tendon.

METHODS

Eleven patients undergoing arthroscopic rotator cuff repair consented to undergo aspiration of bone marrow. A dose-response curve was calculated to determine the optimal dose of insulin needed to differentiate MSCs into tendon. After purification of bone marrow in the operating room, MSCs were exposed to either insulin or tendon-inducing growth factors or were left untreated to serve as a control. The potential for MSCs in each of these groups to differentiate into tendon was evaluated with a multistep process that included determination of the genetic upregulation for tendon-specific proteins, confirmation that the levels of these proteins were actually increased, staining of the MSCs with antibodies for these proteins to ensure that they were expressed on the cell surface, and finally, evaluation of cell morphology to verify the MSCs' tendon-like appearance.

RESULTS

MSCs treated with insulin showed increased gene expression of tendon-specific markers (P < .05), increased content of tendon-specific proteins (P < .05), and increased receptors on the cell surface (P < .05) compared with control cells. Histologic analysis showed a tendon-like appearance compared with the control cells.

CONCLUSIONS

Bone marrow-derived MSCs treated with a single physiologic dose of insulin differentiated into cells with characteristics consistent with tendon.

CLINICAL RELEVANCE

The potential for MSCs to differentiate into tendon after a 1-time dose of insulin may assist in developing practical biologic options for augmentation of rotator cuff repairs.

Increased cellular proliferation in rat skeletal muscle and tendon in response to exercise: use of FLT and PET/CT

PURPOSE

The purpose of this study is to investigate exercise-induced cellular proliferation in rat skeletal muscle/tendon with the use of 3'-[F-18]fluoro-3'deoxythymidine (FLT) and to quantitatively study concomitant changes in the proliferation-associated factor, Ki67.

PROCEDURES

Wistar rats (n = 13) performed 3 days of treadmill running. Cellular proliferation was investigated 3 days before and 48 h after the running exercise with the use of FLT and positron emission tomography/computed tomography (PET/CT). Results were compared to a sedentary control group (n = 10). Image-derived standardized uptake values were calculated for Achilles tendons and calf muscles and compared to gene expression and immunohistochemical evaluations of Ki67.

RESULTS

Treadmill running induced increased uptake of FLT uptake in calf muscles (30%; p < 0.001) and in Achilles tendon (21%, p < 0.001). The image-derived results were supported by a correlation in calf muscle to Ki67 (protein and mRNA level), while this coherence was not found in tendon.

CONCLUSION

FLT-PET seems to be a promising tool for imaging of exercise-induced cellular proliferation in musculo-tendinous tissue.

Tissue engineered biological augmentation for tendon healing: a systematic review

INTRODUCTION

Tendon injuries give rise to significant morbidity. In the last few decades, several techniques have been increasingly used to optimize tendon healing.

SOURCES OF DATA

We performed a comprehensive search of PubMed, Medline, Cochrane, CINAHL and Embase databases using various combinations of the commercial names of each scaffold and the keywords 'tendon', 'rotator cuff', 'supraspinatus tendon', 'Achilles tendon', 'growth factors', 'cytokines', 'gene therapy', 'tissue engineering', 'mesenchymal' and 'stem cells' over the years 1966-2009. All articles relevant to the subject were retrieved, and their bibliographies were hand searched for further references in the context to tissue-engineered biological augmentation for tendon healing.

AREAS OF AGREEMENT

Several new techniques are available for tissue-engineered biological augmentation for tendon healing, growth factors, gene therapy and mesenchimal stem cells.

AREAS OF CONTROVERSY

Data are lacking to allow definitive conclusions on the use of these techniques for routine management of tendon ailments.

GROWING POINTS

The emerging field of tissue engineering holds the promise to use new techniques for tendon augmentation and repair. Preliminary studies support the idea that these techniques can provide an alternative for tendon augmentation with great therapeutic potential.

AREAS TIMELY FOR DEVELOPING RESEARCH

The optimization strategies discussed in this article are currently at an early stage of development. Although these emerging technologies may develop into substantial clinical treatment options, their full impact needs to be critically evaluated in a scientific fashion.

GH and IGF1 levels are positively associated with musculotendinous collagen expression: experiments in acromegalic and GH deficiency patients

OBJECTIVE

Disproportionate growth of musculoskeletal tissue is a major cause of morbidity in both acromegalic (ACRO) and GH-deficient (GHD) patients. GH/IGF1 is likely to play an important role in the regulation of tendon and muscle collagen. We hypothesized that the local production of collagen is associated with the level of GH/IGF1.

DESIGN AND METHODS

As primary outcomes, collagen mRNA expression and collagen protein fractional synthesis rate (FSR) were determined locally in skeletal muscle and tendon in nine ACRO and nine GHD patients. Moreover, muscle myofibrillar protein synthesis and tendon collagen morphology were determined.

RESULTS AND CONCLUSIONS

Muscle collagen I and III mRNA expression was higher in ACRO patients versus GHD patients (P<0.05), whereas collagen protein FSR did not differ significantly between ACRO and GHD patients in muscle (P=0.21) and tendon (P=0.15). IGF1Ea and IGF1Ec mRNA expression in muscle was higher in ACRO patients versus GHD patients (P<0.01). Muscle IGF1Ea mRNA expression correlated positively with collagen I mRNA expression (P<0.01). Tendon collagen fibrillar area tended to be higher in GHD patients relative to ACRO patients (P=0.07). Thus, we observed a higher expression for collagen and IGF1 mRNA in local musculotendinous tissue in ACRO patients relative to GHD patients. Moreover, there was a tendency towards a higher collagen protein FSR and a smaller collagen fibril diameter in ACRO patients relative to GHD patients. The results indicate a collagen-stimulating role of local IGF1 in human connective tissue and add to the understanding of musculoskeletal pathology in patients with either high or low GH/IGF1 axis activity.

Autologous Growth Factors: A Biological Treatment in Sports Medicine

Autologous growth factors have been used in maxillofacial and plastic surgery since the 1990s. The use of preparations rich in growth factors has seen an increase in sports medicine is due to its potential to enhance muscle, tendon, ligament and cartilage healing, and thereby accelerating an athlete's functional return to play. The efficacy of these autologous preparations rich in growth factors has seen varying healing effects for ligament, tendon, muscle, and cartilage injuries. Current clinical evidence is in its infancy with mainly animal and retrospective human studies, but the use of preparations rich in growth factors has increased, given its favourable safety profile and efficient preparation and delivery systems. It is important for physicians to keep abreast with the latest available preparation devices and current clinical evidence looking into the effects of autologous growth factors on tendon, ligament, muscle and cartilage healing.

Growth factor-rich plasma increases tendon cell proliferation and matrix synthesis on a synthetic scaffold: an in vitro study

Numerous scaffolds have been proposed for use in connective tissue engineering. Although these scaffolds direct cell migration and attachment, many are biologically inert and thus lack the physiological stimulus to attract cells and induce mitogenesis and matrix synthesis. In the current study, a bioactive scaffold was created by combining a synthetic scaffold with growth factor-rich plasma (GFRP), an autologous concentration of growth factors derived from a platelet-rich plasma preparation. In vitro tendon cell proliferation and matrix synthesis on autologous GFRP-enriched scaffolds, autologous serum-enriched scaffolds, and scaffolds alone were compared. The GFRP preparation was found to have a 4.7-fold greater concentration of a sentinel growth factor (transforming growth factor-beta1) compared with serum. When combined with media containing calcium, the GFRP produced a thin fibrin matrix over and within the GFRP-enriched scaffolds. Cell proliferation assays demonstrated that GFRP-enriched scaffolds significantly enhanced cell proliferation over autologous serum and control groups at both 48 and 72 h. Analysis of the scaffolds at 14, 21, and 28 days revealed that GFRP-enriched scaffolds significantly increased the deposition of a collagen-rich extracellular matrix when compared with the other groups. These results indicate that GFRP can be used to enhance in vitro cellular population and matrix deposition of tissue-engineered scaffolds.

The pathogenesis of tendinopathy: balancing the response to loading

Tendons are designed to withstand considerable loads. Mechanical loading of tendon tissue results in upregulation of collagen expression and increased synthesis of collagen protein, the extent of which is probably regulated by the strain experienced by the resident fibroblasts (tenocytes). This increase in collagen formation peaks around 24 h after exercise and remains elevated for about 3 days. The degradation of collagen proteins also rises after exercise, but seems to peak earlier than the synthesis. Despite the ability of tendons to adapt to loading, repetitive use often results in injuries, such as tendinopathy, which is characterized by pain during activity, localized tenderness upon palpation, swelling and impaired performance. Tendon histological changes include reduced numbers and rounding of fibroblasts, increased content of proteoglycans, glycosaminoglycans and water, hypervascularization and disorganized collagen fibrils. At the molecular level, the levels of messenger RNA for type I and III collagens, proteoglycans, angiogenic factors, stress and regenerative proteins and proteolytic enzymes are increased. Tendon microrupture and material fatigue have been suggested as possible injury mechanisms, thus implying that one or more 'weak links' are present in the structure. Understanding how tendon tissue adapts to mechanical loading will help to unravel the pathogenesis of tendinopathy.

Asynchronous muscle and tendon adaptation after surgical tensioning procedures

BACKGROUND

Donor muscles are often highly stretched in tendon transfer surgery. Despite literature reports that showed adaptation of the serial sarcomere number to moderate stretch, little is known regarding adaptation to stretch outside of the physiological range (commonly seen in clinical tendon transfer). This study was performed to evaluate muscle-tendon-unit adaptation to tendon transfer surgery in an animal model.

METHODS

Thirty-seven male New Zealand White rabbits were used for muscle analysis, and twenty-five of those rabbits were also used for biological analysis of the tendons after the experiment. The extensor digitorum muscle of the second toe was transferred at a specific sarcomere length of 3.7 microm, chosen to be near the end of the descending limb of the rabbit sarcomere length-tension curve. Animals were killed at five time points, at which complete muscle architectural analysis as well as measurements of tendon dimension, tendon water content, and tendon cytokine transcript levels were performed.

RESULTS

As expected, a rapid increase in the serial sarcomere number (mean and standard error of the mean, 4658 +/- 154 in the transferred muscle compared with 3609 +/- 80 in the control muscle) was found one week after the surgery. From this time point until eight weeks, this increased serial sarcomere number paradoxically decreased, while the sarcomere length remained constant. Eventually, at eight weeks, it reached the same value (3749 +/- 83) as that in the control muscle (3767 +/- 61). Tendon adaptation was delayed relative to muscle adaptation, but it was no less dramatic. Tendon length increased by 1.43 +/- 0.74 mm over the eight-week time period, corresponding to a strain of 15.55% +/- 4.08%.

CONCLUSIONS

To our knowledge, this is the first report of biphasic adaptation of the serial sarcomere number followed by tendon adaptation, and it indicates that muscle adapts more quickly than tendon does. Taken together, these results illustrate a complex and unique interaction between muscles and tendons that occurs during adaptation to stretching during tendon transfer.

From mechanical loading to collagen synthesis, structural changes and function in human tendon

The adaptive response of connective tissue to loading requires increased synthesis and turnover of matrix proteins, with special emphasis on collagen. Collagen formation and degradation in the tendon increases with both acute and chronic loading, and data suggest that a gender difference exists, in that females respond less than males with regard to an increase in collagen formation after exercise. It is suggested that estrogen may contribute toward a diminished collagen synthesis response in females. Conversely, the stimulation of collagen synthesis by other growth factors can be shown in both animal and human models where insulin-like growth factor 1 (IGF-I) and transforming growth factor-beta-1 (TGF-beta-1) expression increases to accompany or precede an increase in procollagen expression and collagen synthesis. In humans, it can be demonstrated that an increase in the interstitial concentration of TGF-beta, PGE2, IGF-I plus its binding proteins and interleukin-6 takes place after exercise. The increase in IGF-I expression in tendon includes the isoform that has so far been thought only to exist in skeletal muscle (mechano growth factor). The increase in IGF-I and procollagen expression showed a similar response whether the tendon was stimulated by concentric, isometric or eccentric muscle contraction, suggesting that strain rather that stress/torque determines the collagen-synthesis stimulating response seen with exercise. The adaptation time to chronic loading is longer in tendon tissue compared with contractile elements of skeletal muscle or the heart, and only with very prolonged loading are significant changes in gross dimensions of the tendon observed, suggesting that habitual loading is associated with a robust change in the size and mechanical properties of human tendons. An intimate interplay between mechanical signalling and biochemical changes in the matrix is needed in tendon, such that chemical changes can be converted into adaptations in the morphology, structure and material properties.

Mesenchymal stem cells and insulin-like growth factor-I gene-enhanced mesenchymal stem cells improve structural aspects of healing in equine flexor digitorum superficialis tendons

Tendinitis remains a catastrophic injury among athletes. Mesenchymal stem cells (MSCs) have recently been investigated for use in the treatment of tendinitis. Previous work has demonstrated the value of insulin-like growth factor-I (IGF-I) to stimulate cellular proliferation and tendon fiber deposition in the core lesion of tendinitis. This study examined the effects of MSCs, as well as IGF-I gene-enhanced MSCs (AdIGF-MSCs) on tendon healing in vivo. Collagenase-induced bilateral tendinitis lesions were created in equine flexor digitorum superficialis tendons (SDFT). Tendons were treated with 10 x 10(6) MSCs or 10 x 10(6) AdIGF-MSCs. Control limbs were injected with 1 mL of phosphate-buffered saline (PBS). Ultrasound examinations were performed at t = 0, 2, 4, 6, and 8 weeks. Horses were euthanized at 8 weeks and SDFTs were mechanically tested to failure and evaluated for biochemical composition and histologic characteristics. Expression of collagen types I and III, IGF-I, cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-3 (MMP-3), matrix metalloproteinase-13 (MMP-13), and aggrecanase-1 (ADAMTS-4) were similar in MSC and control tendons. Both MSC and AdIGF-MSC injection resulted in significantly improved tendon histological scores. These findings indicate a benefit to the use of MSCs and AdIGF-MSCs for the treatment of tendinitis.

In vivo local administration of osteogenic protein-1 increases structural properties of the overstretched anterior cruciate ligament with partial midsubstance laceration

We report the effects of local administration of osteogenic protein-1 on the biomechanical properties of the overstretched anterior cruciate ligament in an animal model. An injury in the anterior cruciate ligament was created in 45 rabbits. They were divided into three equal groups. In group 1, no treatment was applied, in group II, phosphate-buffered saline was applied around the injured ligament, and in group III, 12.5 μg of osteogenic protein-1 mixed with phosphate-buffered saline was applied around the injured ligament. A control group of 15 rabbits was assembled from randomly-selected injured knees from among the first three groups. Each rabbit was killed at 12 weeks.

The maximum load and stiffness of the anterior cruciate ligament was found to be significantly greater in group III than either group 1 (p = 0.002, p = 0.014) or group II (p = 0.032, p = 0.025). The tensile strength and the tangent modulus of fascicles from the ligament were also significantly greater in group III than either group I (p = 0.002, p = 0.0174) or II (p = 0.005, p = 0.022).

The application of osteogenic protein-1 enhanced the healing in the injured anterior cruciate ligament, but compared with the control group the treated ligament remained lengthened. The administration of osteogenic protein-1 may have a therapeutic role in treating the overstretched anterior cruciate ligament.

Adeno-associated virus-2-mediated bFGF gene transfer to digital flexor tendons significantly increases healing strength. an in vivo study

BACKGROUND

Treatment of the disrupted intrasynovial flexor tendon is troublesome and can be complicated by the rupture of weak repairs and the formation of adhesions. The central issue underlying the unsatisfactory outcomes is the lack of sufficient healing capacity, which prohibits aggressive postoperative tendon motion. Transfer of genes that are critical to healing by means of an efficient vector system offers a promising way of strengthening the repair. The purpose of the present study was to transfer the basic fibroblast growth factor gene through the adeno-associated viral-2 vector to injured digital flexor tendons and to investigate its effects on the healing strength of the tendon and on adhesion formation in a clinically relevant injury model.

METHODS

One hundred and twenty-eight long toes from sixty-four white leghorn chickens were used. The flexor digitorum profundus tendons were cut completely in the digital sheath area and were repaired with the modified Kessler method. In Group 1, a total of 2 x 10(9) particles of adeno-associated viral vector harboring the basic fibroblast growth factor gene were injected into both ends of the cut tendon. In Group 2, the same amount of adeno-associated viral vector carrying the luciferase gene was injected. In Group 3 (the non-injection control group), the tendons were sutured without any injection. At the end of two, four, eight, and twelve weeks, the toes were harvested and the tendons were tested for determination of the load-to-failure strength. At the end of eight and twelve weeks, the energy required to flex the toes was tested. The morphology regarding healing status and adhesions around the tendon were evaluated at two, four, eight, and twelve weeks.

RESULTS

The ultimate strength of repaired tendons that had been treated with adeno-associated viral vector-basic fibroblast growth factor was significantly greater than that of tendons that had been treated with the sham vector or simple repair both during the early healing period (two weeks, p < 0.01; four weeks, p < 0.01) and a later period (eight weeks, p < 0.05). At four weeks, the strength of tendons that had been treated with adeno-associated viral vector-basic fibroblast growth factor (8.9 +/- 1.9 N) was significantly greater than that of tendons that had been treated with sham vector (6.1 +/- 1.0 N) (p < 0.01) or simple suture (5.7 +/- 1.1 N) (p < 0.001). Statistically, the grading of adhesions was the same among all three groups at four and eight weeks, but at twelve weeks it was significantly less severe for tendons that had been treated with adeno-associated viral vector-basic fibroblast growth factor than for those that had been treated with simple suture (p < 0.05). The energy that was required to flex the toes after treatment with adeno-associated viral vector-basic fibroblast growth factor was not increased at eight or twelve weeks compared with that in the controls.

CONCLUSIONS

The present study demonstrates that basic fibroblast growth factor gene transfer to digital flexor tendons by means of adeno-associated viral vector-2 significantly increases healing strength during the critical tendon healing period but does not increase adhesion formation.

Effect of osteogenic protein-1 on the matrix metabolism of bovine tendon cells

Tendon rupture is a common sports injury in adults. However, the mechanical properties of repair tissue are inferior to those of normal tissue. To accelerate tendon healing, an in vivo approach using growth factors has been applied and has shown evidence for the efficacy of biological stimulation of the repair process. Recombinant human osteogenic protein-1 (rhOP-1) has been shown to be effective in stimulating matrix production by various connective tissues. To test the effect of rhOP-1 on the matrix metabolism of tendon cells in vitro, bovine tendon cells were cultured in monolayer with various doses of rhOP-1 for 7 days. The addition of rhOP-1 to cell culture media resulted in significant increases in cell proliferation, DNA content, and the synthesis of proteoglycans (PGs) and collagen, compared to control cultures. The relative percentage of large PGs in the OP-1 culture was higher than that in the control culture. In conclusion, we show for the first time that rhOP-1 stimulates the proliferation of tendon cells and their ability to synthesize and accumulate PGs and collagen in their extracellular matrix. These biological properties may be used in the tissue-engineering of tendon tissues.

Systemic administration of IGF-I enhances healing in collagenous extracellular matrices: evaluation of loaded and unloaded ligaments

BACKGROUND

Insulin-like growth factor-I (IGF-I) plays a crucial role in wound healing and tissue repair. We tested the hypotheses that systemic administration of IGF-I, or growth hormone (GH), or both (GH+IGF-I) would improve healing in collagenous connective tissue, such as ligament. These hypotheses were examined in rats that were allowed unrestricted activity after injury and in animals that were subjected to hindlimb disuse. Male rats were assigned to three groups: ambulatory sham-control, ambulatory-healing, and hindlimb unloaded-healing. Ambulatory and hindlimb unloaded animals underwent surgical disruption of their knee medial collateral ligaments (MCLs), while sham surgeries were performed on control animals. Healing animals subcutaneously received systemic doses of either saline, GH, IGF-I, or GH+IGF-I. After 3 weeks, mechanical properties, cell and matrix morphology, and biochemical composition were examined in control and healing ligaments.

RESULTS

Tissues from ambulatory animals receiving only saline had significantly greater strength than tissue from saline receiving hindlimb unloaded animals. Addition of IGF-I significantly improved maximum force and ultimate stress in tissues from both ambulatory and hindlimb unloaded animals with significant increases in matrix organization and type-I collagen expression. Addition of GH alone did not have a significant effect on either group, while addition of GH+IGF-I significantly improved force, stress, and modulus values in MCLs from hindlimb unloaded animals. Force, stress, and modulus values in tissues from hindlimb unloaded animals receiving IGF-I or GH+IGF-I exceeded (or were equivalent to) values in tissues from ambulatory animals receiving only saline with greatly improved structural organization and significantly increased type-I collagen expression. Furthermore, levels of IGF-receptor were significantly increased in tissues from hindlimb unloaded animals treated with IGF-I.

CONCLUSION

These results support two of our hypotheses that systemic administration of IGF-I or GH+IGF-I improve healing in collagenous tissue. Systemic administration of IGF-I improves healing in collagenous extracellular matrices from loaded and unloaded tissues. Growth hormone alone did not result in any significant improvement contrary to our hypothesis, while GH + IGF-I produced remarkable improvement in hindlimb unloaded animals.

Mechanical Conditioning of Cell-Seeded Small Intestine Submucosa: A Potential Tissue-Engineering Strategy for Tendon Repair

Our long-term objective is to enhance tendon repair by delivering cells on natural biologic scaffolds to the repair site. Clinical outcomes may be improved by first preconditioning these cell-seeded constructs in bioreactors to enhance their properties at implantation and to deliver cells expressing a desired phenotype. In this work, we have investigated the effect of in vitro mechanical conditioning on small-intestine submucosa (SIS) scaffolds seeded with primary tendon cells (tenocytes). SIS scaffolds (with and without cells) were conditioned under various loading regimes over a 2-week period. In vitro cyclic loading significantly increased the biomechanical properties (e.g., stiffness) of cell-seeded SIS constructs (129.1 +/- 10.2%) from time 0. The stiffness change of cyclically loaded constructs without cells was 33.9 +/- 13.8% and of statically loaded constructs with cells was 34.0 +/- 15.2% and without cells was 33.4 +/- 10.7%. In the cell-seeded groups, our data demonstrate a direct role (e.g., cell tensioning) for cells in construct stiffening. In addition, the initial stiffness of the cell-seeded, cyclically loaded constructs was found to be a strong predictor of the change in construct stiffness. Despite the mechanical integrity of these constructs being significantly less than native tendon, our data show that structural properties can be improved with in vitro mechanical conditioning. These data provide the basis for future studies investigating in vitro conditioning (mechanical, chemical) of cell-seeded ECM scaffolds and the use of such constructs for enhancing tendon repair in vivo.

Comparison of surgically repaired Achilles tendon tears using platelet-rich fibrin matrices

BACKGROUND

Platelet-rich fibrin matrices release a natural mixture of growth factors that play central roles in the complex processes of tendon healing.

HYPOTHESIS

Application of autologous platelet-rich matrices during Achilles tendon surgery may promote healing and functional recovery.

STUDY DESIGN

Case-control study and descriptive laboratory study; Level of evidence, 3.

METHODS

Twelve athletes underwent open suture repair after complete Achilles tendon tear. Open suture repair in conjunction with a preparation rich in growth factors (PRGF) was performed in 6 athletes and retrospectively compared with a matched group that followed conventional surgical procedure. The outcomes were evaluated on the basis of range of motion, functional recovery, and complications. Achilles tendons were examined by ultrasound at 50 +/- 11 months in retrospective controls and 32 +/- 10 months in the PRGF group. In the laboratory portion of the study, PRGF treatment was characterized by the number of platelets and concentration of insulin (IGF-I), transformed (TGF-beta1), platelet-derived (PDGF-AB), vascular endothelial (VEGF), hepatocyte (HGF), and epidermal (EGF) growth factors in patients affected by musculoskeletal traumatic injuries.

RESULTS

Athletes receiving PRGF recovered their range of motion earlier (7 +/- 2 weeks vs 11 +/- 3 weeks, P = .025), showed no wound complication, and took less time to take up gentle running (11 +/- 1 weeks vs 18 +/- 3 weeks, P = .042) and to resume training activities (14 +/- 0.8 weeks vs 21 +/- 3 weeks, P = .004). The cross-sectional area of the PRGF-treated tendons increased less (t = 3.44, P = .009). TGF-beta1 (74.99 +/- 32.84 ng/mL), PDGF-AB (35.62 +/- 14.57 ng/mL), VEGF (383.9 +/- 374.9 pg/mL), EGF (481.5 +/- 187.5 pg/mL), and HGF (593.87 +/- 155.76 pg/mL) significantly correlated with the number of platelets (677 +/- 217 platelets/microL, P < .05).

CONCLUSION

The operative management of tendons combined with the application of autologous PRGF may present new possibilities for enhanced healing and functional recovery. This needs to be evaluated in a randomized clinical trial.

Tendon Healing In Vitro: Adeno-Associated Virus-2 Effectively Transduces Intrasynovial Tenocytes with Persistent Expression of the Transgene, but Other Serotypes Do Not

BACKGROUND

Transfer of exogenous growth factor genes to injured tendons offers a promising method for strengthening tendon repairs. Adeno-associated virus vectors have advantages of being both nonpathogenic and nontoxic. The authors explored the efficiency of transduction of intrasynovial tenocytes with different serotypes of adeno-associated virus (AAV) and the persistency of its expression of a growth factor transgene.

METHODS

Tenocytes were obtained from cultures of rat intrasynovial tendons and distributed to 82 wells in eight culture plates and to 30 culture dishes. The tenocytes in the wells were treated with AAV1, AAV2, AAV3, AAV4, AAV5, AAV7, and AAV8 vectors containing the lacZ gene, and plasmid vectors (pCMVbeta-lacZ). The tenocytes were stained with in situ beta-galactosidase 5 days later. The basic fibroblast growth factor (bFGF) gene was cloned to the AAV2 vector to construct the AAV2-bFGF vector, which transduced tenocytes in culture dishes. Expression of the transgene was measured over 3 weeks and analyzed statistically.

RESULTS

AAV2 effectively delivered exogenous genes to proliferating intrasynovial tenocytes. In contrast, other tested adeno-associated viruses transduced tenocytes minimally or not at all. The efficiency of gene transfer by AAV2, indicated by the percentage of cells with positive beta-galactosidase staining, was significantly greater than that by a plasmid vector (p = 0.001). Expression of the bFGF gene in tenocytes transduced with the AAV2-bFGF was significantly higher than that in the control over the 3-week period (p < 0.01).

CONCLUSIONS

Gene transfer to tenocytes by AAV2 is more efficient than that by a plasmid vector. However, other adeno-associated virus serotypes cannot effectively transduce tenocytes. The bFGF gene can be delivered to intrasynovial tenocytes by the AAV2 vector effectively, and the gene transfer significantly increases expression of bFGF gene over 3 weeks.

Tendon injuries across the world: treatment

This article outlines current status of primary and secondary surgical treatment of flexor and extensor tendon injuries in the hand and rehabilitation regimens worldwide. Unsolved problems associated with tendon repairs in the hand are tendon adhesions, rupture of the repairs, finger stiffness, power of hand motion, and surgical skills. Future development may include improvement of tendon healing through biological approaches, repair techniques, and, in particular, establishment of adequate rehabilitation systems and training of surgeons in some regions of the world.