Application of Tendon Stem/Progenitor Cells and Platelet-Rich Plasma to Treat Tendon Injuries

Platelet-rich plasma in the pathologic processes of tendinopathy: a review of basic science studies

Tendinopathy is a medical condition that includes a spectrum of inflammatory and degenerative tendon changes caused by traumatic or overuse injuries. The pathological mechanism of tendinopathy has not been well defined, and no ideal treatment is currently available. Platelet-rich plasma (PRP) is an autologous whole blood derivative containing a variety of cytokines and other protein components. Various basic studies have found that PRP has the therapeutic potential to promote cell proliferation and differentiation, regulate angiogenesis, increase extracellular matrix synthesis, and modulate inflammation in degenerative tendons. Therefore, PRP has been widely used as a promising therapeutic agent for tendinopathy. However, controversies exist over the optimal treatment regimen and efficacy of PRP for tendinopathy. This review focuses on the specific molecular and cellular mechanisms by which PRP manipulates tendon healing to better understand how PRP affects tendinopathy and explore the reason for the differences in clinical trial outcomes. This article has also pointed out the future direction of basic research and clinical application of PRP in the treatment of tendinopathy, which will play a guiding role in the design of PRP treatment protocols for tendinopathy.

Global research trends on platelet-rich plasma for tendon and ligament injuries from the past two decades: A bibliometric and visualized study

Background

In sports medicine, tendon and ligament injuries are the most prevalent conditions, and with the booming of sports competition, the incidence of sports injuries is gradually increasing, investigating more potent therapeutic options is therefore becoming increasingly crucial. Platelet-rich plasma therapy has gained popularity as an effective and secure treatment in recent years. Currently, a faceted systematic and clear visual analysis is lacking in this research area.

Methods

The literature related to using platelet-rich plasma to treat ligament and tendon injuries from 2003 to 2022 in the core dataset of the Web of Science database was collected and analyzed visually using Citespace 6.1 software. Research hotspots and development trends were analyzed in terms of high-impact countries or regions, authors, research institutions, keywords, and cited literature.

Results

The literature comprised a total of 1,827 articles. The annual publication volume of relevant literature has demonstrated a significant development tendency as the field of platelet-rich plasma research for tendon and ligament injuries has heated up in recent years. With 678 papers, the United States came in top place, followed by China with 187 papers. Hosp Special Surg ranked first with 56 papers. The hot research topics analyzed by keywords were tennis elbow, anterior cruciate ligament, rotator cuff repair, achilles tendon, mesenchymal stem cells, guided tissue regeneration, network meta analysis, chronic patellar tendinopathy, and follow up.

Conclusion

Analysis of the research literature over the past 20 years shows that the United States and China will continue to dominate in terms of volume of publications based on annual volume and trends, with some collaboration among high-impact authors and further collaboration still needed in different countries and institutions. Platelet-rich plasma is widely used in the treatment of tendon ligament injuries. Its clinical efficacy is influenced by a number of factors, the main ones being the inconsistency in the preparation and composition of platelet-rich plasma and its related preparations, and the differences in efficacy due to different activation methods of platelet-rich plasma, as well as factors such as injection time, injection site, administration method, number of administrations, acidity and evaluation methods, In addition, the applicability to different injury diseases remains controversial. In recent years, the molecular biology of platelet-rich plasma for tendon ligament therapy has received increasing attention.

The Functions and Mechanisms of Basic Fibroblast Growth Factor in Tendon Repair

Tendon injury is a disorder of the musculoskeletal system caused by overuse or trauma, which is characterized by pain and limitations in joint function. Since tendon healing is slowly and various treatments are generally ineffective, it remains a clinically challenging problem. Recent evidences suggest that basic fibroblast growth factor (bFGF) not only plays an important role in tendon healing, but also shows a positive effect in laboratory experimentations. The purpose of this review is to summarize the effects of bFGF in the tendon healing. Firstly, during the inflammatory phase, bFGF stimulates the proliferation and differentiation of vascular endothelial cells to foster neovascularization. Furthermore, bFGF enhances the production of pro-inflammatory factors during the early phase of tendon healing, thereby accelerating the inflammatory response. Secondly, the cell proliferation phase is accompanied by the synthesis of a large number of extracellular matrix components. bFGF speeds up tendon healing by stimulating fibroblasts to secrete type III collagen. Lastly, the remodeling phase is characterized by the transition from type III collagen to type I collagen, which can be promoted by bFGF. However, excessive injection of bFGF can cause tendon adhesions as well as scar tissue formation. In future studies, we need to explore further applications of bFGF in the tendon healing process.

Innovative Strategies in Tendon Tissue Engineering

The tendon is a highly aligned connective tissue that transmits force from muscle to bone. Each year, more than 32 million tendon injuries have been reported, in fact, tendinopathies represent at least 50% of all sports injuries, and their incidence rates have increased in recent decades due to the aging population. Current clinical grafts used in tendon treatment are subject to several restrictions and there is a significant demand for alternative engineered tissue. For this reason, innovative strategies need to be explored. Tendon replacement and regeneration are complex since scaffolds need to guarantee an adequate hierarchical structured morphology and mechanical properties to stand the load. Moreover, to guide cell proliferation and growth, scaffolds should provide a fibrous network that mimics the collagen arrangement of the extracellular matrix in the tendons. This review focuses on tendon repair and regeneration. Particular attention has been devoted to the innovative approaches in tissue engineering. Advanced manufacturing techniques, such as electrospinning, soft lithography, and three-dimensional (3D) printing, have been described. Furthermore, biological augmentation has been considered, as an emerging strategy with great therapeutic potential.

Comparison of midterm results of Platelet Rich Plasma (PRP) versus Steroid for plantar fasciitis: A randomized control trial of 118 patients

BACKGROUND

Plantar fasciitis, which is a common cause of heel pain, often results in significant morbidity. In cases who are not responsive to initial conservative treatment, invasive procedures, often in the form of local infiltration of steroid are required. These procedures are associated with significant complications. Local Platelet Rich Plasma (PRP) infiltration is an emerging addition to these treatments. However, whether it is more effective in reducing pain and improving function than other treatments (such as steroid injections or whole blood) remains controversial.

METHODS

Skeletally mature patients with plantar fasciitis who had failed conservative therapy were randomized using envelope method into 2 groups: PRP and Steroid group. The participants were assessed for pain using Visual Analog Scale on the day of presentation, and then after therapy at 2 weeks, 4 weeks, 3 months, and 6 months. They were additionally assessed on final follow-up using AOFAS hind-foot Score.

RESULTS

118 patients were randomized into 2 groups: 58 patients to the PRP group and 60 to the Steroid group. PRP was associated with greater improvement in VAS score and resulted in superior AOFAS score at 6 months as compared to steroid injection. The authors did not find any local or systemic complications in any of the groups. The result and difference were more pronounced as the time from injection increased and maximal benefit was observed at 6 months follow-up. None of the patients needed a repeat injection at 6 months.

CONCLUSION

Our study expands on the previous studies to provide a better evidence for superiority of PRP over local injection of steroid in plantar fasciitis, and the authors conclude that PRP provides better pain relief and function as compared to steroid injection.

LEVEL OF EVIDENCE

Level 1 Prospective Randomized Control Trial (RCT).

Tensile strength, growth factor content and proliferation activities for two platelet concentrates of platelet-rich fibrin and concentrated growth factor

Background/purpose

Platelet-rich fibrin (PRF) can be obtained by centrifuging fresh blood in the absence of anticoagulants. Varying the centrifugation speeds may produce tougher and richer concentrated growth factors (CGF). This study examines tensile strength, growth factor content, and the potential of CGF and PRF in promoting periodontal cell proliferation.

Materials and methods

Blood (40 mL/subject) was collected from 44 healthy subjects. PRF and CGF were prepared by centrifuging at 3000 rpm and switching speeds ranging within 3000 rpm, respectively. Fibrin strip was prepared and its tensile strength was measured. Transforming growth factor beta 1 (TGF-β1), platelet-derived growth factor BB (PDGF-BB), and epidermal growth factor (EGF) in the residual serum and fibrin clots were determined by enzyme-linked immunosorbent assay, and their effects on the proliferation of hFOB1.19 osteoblasts and human gingival fibroblasts were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay.

Results

Compared with PRF, tensile strength of CGF was significantly higher. Concentrations and amounts of PDGF-BB and EGF in CGF were significantly higher than those in PRF. Osteoblast number was significantly higher in the cultures with fetal bovine serum (FBS, 10%) and with PRF or CGF fibrin clots (5%, 10%, and 50%) compared to that without FBS. Moreover, osteoblast number in CGF, regardless of the preparation of 10% and 50%, was significantly greater than that in PRF. Similar findings were also observed for gingival fibroblasts among the various subjects.

Conclusion

Varying centrifugation speeds can modify the tensile strength and biological activities of platelet fibrin clots.

Pulsed Radiofrequency Neuromodulation Contributes to Activation of Platelet-Rich Plasma in In Vitro Conditions

OBJECTIVES

Recent years have brought new developments in interventional chronic pain management, namely regenerative orthopedics utilizing platelet-rich plasma (PRP) as well as further evolution of pulsed radiofrequency neuromodulation (PRF). Both methods have been used separately. Here, we investigated whether PRF may potentiate the activation of platelets in PRP samples when both these techniques are combined together in in vitro conditions.

MATERIALS AND METHODS

Studies were performed on concentrated PRP samples (PRPs) obtained from acid citrate dextrose-treated blood taken from 11 healthy volunteers. PRPs were divided into four groups: 1) nonactivated PRP; 2) thrombin-activated PRP as a positive control for maximal platelets activation; 3) PRF-treated PRP exposed for 20 min to PRF energy generated by neurotherm radio frequency generator at 500 kHz, with a voltage of 40 V and maximal temperature of 42°C; and 4) a combination of groups 2 and 3.

RESULTS

PRF-induced platelet activation measured by platelet factor 4 (PF4) and ATP release from PRPs was significantly higher compared to nonactivated PRPs, and similar to PF4 and ATP release from thrombin-activated PRPs. Thrombin activation did not potentiate PF4 release in PRF samples and even reduced ATP level. Additionally, PRF neither induced any platelet membrane damage measured by lactic dehydrogenase release from PRP nor modified any platelets viability or metabolism measured by MTT.

CONCLUSIONS

We confirmed that PRF may activate PRP without additional platelet activators. So, a combination of both methods PRF and PRP application may provide a more effective opportunity for tissue regeneration in dentistry, surgery, dermatology, or in orthopedics.

LncRNA TUG1 promoted osteogenic differentiation through promoting bFGF ubiquitination

LncRNA TUG1 has the potential to promote the osteogenic differentiation of several cells, but the role of lncRNA TUG1 in osteogenic differentiation of tendon stem/progenitor cells (TSPCs) is still unknown. This study aims to determine the role of lncRNA TUG1 in osteogenic differentiation of TSPCs. bFGF, RUNX2, and Osterix protein expressions were detected by western blot. LncRNA TUG1 and bFGF expression was detected by qRT-PCR. RNA immunoprecipitation (RIP) assay was used to confirm the interaction between TUG1 and bFGF2. Ubiquitination assay was used to determine the ubiquitination of bFGF protein. During osteogenic differentiation, the protein expression of bFGF was significantly downregulated in TSPCs, and the expression of TUG1 was significantly elevated in TSPCs. Interfering TUG1 or overexpressing bFGF suppressed osteogenic differentiation of TSPCs. In addition, lncRNA TUG1 interacted with bFGF, and lncRNA TUG1 promoted the ubiquitination of bFGF protein. We also determined that lncRNA TUG1 downregulated bFGF protein expression through promoting the ubiquitination of bFGF. LncRNA TUG1 promoted the osteogenic differentiation of TSPCs through promoting bFGF ubiquitination.

Biologics and stem cell-based therapies for rotator cuff repair

The rotator cuff is composed of several distinct muscles and tendons that function in concert to coordinate shoulder motion. Injuries to these tendons frequently result in permanent dysfunction and persistent pain. Despite considerable advances in operation techniques, surgical repair alone still does not fully restore rotator cuff function. This review focuses on recent research in the use of biologics and stem cell-based therapies to augment repair, highlighting promising avenues for future work and remaining challenges. While a number of animal models are used for rotator cuff studies, the anatomy of the rotator cuff varies dramatically between species. Since the rodent rotator cuff shares the most anatomical features with the human, this review will focus primarily on rodent models to enable consistent interpretation of outcome measures.

Characteristics of tendon derived stem cells according to different factors to induce the tendinopathy

Tendon derived stem cells (TDSCs) have been used as a therapeutic agent and as a healing marker. However, there has been no study about the characteristics of TDSCs extracted from tendinopathic tendon tissues. The aim of this study was to find the different characteristics of TDSCs according to the factors to induce the tendinopathy. Five- and fifteen-week old Sprague Dawley rats were used for this study and chemically-induced and injury-induced tendinopathy models were made depending on the age of the animal for different types of tendinopathy. TDSCs from chemically-induced tendinopathy showed markedly low proliferation compared to those from age-matched normal control and injury-induced tendinopathy. In addition, TDSCs from chemically-induced tendinopathy progressed to osteogenesis under an osteogenic differentiation environment more than those from other groups. In contrast, TDSCs from injury-induced tendinopathy showed markedly high proliferation and high expression of type III collagen and α-SMA compared to other groups. Adipogenic potentials in TDSCs from injury-induced tendinopathy were also higher. These different characteristics might be helpful in the development new therapeutic agents for tendon regeneration according to different factors to induce the tendinopathy.

Effects of bone marrow aspirate concentrate and platelet-rich plasma on patients with partial tear of the rotator cuff tendon

Background

We compared the clinical course of rotator cuff tears between rotator cuff exercise and bone marrow aspirate concentration (BMAC)-platelet rich plasma (PRP) injection to identify the therapeutic effects of BMAC-PRP on partial tear of the rotator cuff tendon.

Methods

Twenty-four patients with partial tear of the rotator cuff tendon participated in this study. Twelve patients underwent extraction of BMACs and PRP and received the injection of BMAC-PRP at the tear site under ultrasound guidance. Twelve patients in the control group were asked to perform the rotator cuff exercise for 3 months. Visual analog scale (VAS) and manual muscle test (MMT) scores of the supraspinatus muscle were measured, and the American Shoulder and Elbow Surgeons (ASES) score was recorded before, 3 weeks, and 3 months after injection. Tear size was measured by the greatest longitudinal tear length.

Results

The change in the VAS differed between groups at 3 months (P = 0.039) but not at 3 weeks (P = 0.147). The ASES scores in the BMAC-PRP group changed from 39.4 ± 13.0 to 54.5 ± 11.5 at 3 weeks and 74.1 ± 8.5 at 3 months while those in the control group changed from 45.9 ± 12.4 to 56.3 ± 12.3 at 3 weeks (P = 0.712) and 62.2 ± 12.2 at 3 months (P = 0.011). The tear size decreased at 3 weeks or 3 months after the BMAC-PRP injection but was not significantly different from that in the control group.

Conclusions

BMAC-PRP improved pain and shoulder function in patients with partial tear of the rotator cuff tendon.

Trial registration

The patients were registered in the institutional board registry of Samsung Medical Center (registry number 2014-07-173).

Electronic supplementary material

The online version of this article (10.1186/s13018-017-0693-x) contains supplementary material, which is available to authorized users.

Platelet-rich plasma as a treatment for plantar fasciitis: A meta-analysis of randomized controlled trials

BACKGROUND

Recently, platelet-rich plasma (PRP) has been used as an alternative therapy for plantar fasciitis (PF) to reduce heel pain and improve functional restoration. We evaluated the current evidence concerning the efficacy and safety of PRP as a treatment for PF compared with the efficacy and safety of steroid treatments.

METHODS

Databases (PubMed, EMBASE, and The Cochrane Library) were searched from their establishment to January 30, 2017, for randomized controlled trials (RCTs) comparing PRP with steroid injections as treatments for PF. The Cochrane risk of bias (ROB) tool was used to assess the methodological quality. Outcome measurements were the visual analogue scale (VAS), Foot and Ankle Disability Index (FADI), American Orthopedic Foot and Ankle Society (AOFAS) scale, and the Roles and Maudsley score (RMS). The statistical analysis was performed with RevMan 5.3.5 software.

RESULTS

Nine RCTs (n = 430) were included in this meta-analysis. Significant differences in the VAS were not observed between the 2 groups after 4 [weighted mean difference (WMD) = 0.56, 95% confidence interval (95% CI): -1.10 to 2.23, P = .51, I = 89%] or 12 weeks of treatment (WMD = -0.49, 95% CI: -1.42 to 0.44, P = .30, I = 89%). However, PRP exhibited better efficacy than the steroid treatment after 24 weeks (WMD = -0.95, 95% CI: -1.80 to -0.11, P = .03, I = 85%). Moreover, no significant differences in the FADI, AOFAS, and RMS were observed between the 2 therapies (P > .05).

CONCLUSION

Limited evidence supports the conclusion that PRP is superior to steroid treatments for long-term pain relief; however, significant differences were not observed between short and intermediate effects. Because of the small sample size and the limited number of high-quality RCTs, additional high-quality RCTs with larger sample sizes are required to validate this result.

Advances of stem cell based-therapeutic approaches for tendon repair

Tendon injuries are significant clinical problems. Current treatments often result in incomplete repair or healing, which may lead to reduced function and rupture. Stem cell-based therapy is a promising intervention for tendon repair. In this article, we attempt to provide a brief overview on the recent progress in the field, current understanding of the underlying mechanisms of the approach, and the potential of stem cell-based therapies beyond cell implantation. We conclude the review by sharing our viewpoints on the challenges, opportunities, and future directions of this approach. The translational potential of this article: This paper reviews recent progress on stem cell-based therapeutic approaches for tendon repair, which highlights its translational potential and challenges.

A systematic review and meta-analysis of platelet-rich plasma versus corticosteroid injections for plantar fasciopathy

PURPOSE

To determine whether platelet-rich plasma (PRP) injections are associated with improved pain and function scores when compared with corticosteroid injections for plantar fasciopathy.

METHODS

A systematic review of published literature was performed for studies comparing PRP injections and corticosteroid injections for plantar fasciopathy. Studies were assessed using the Cochrane Risk of Bias Tool and the Newcastle Ottawa Scale (NOS). The primary endpoint was pain and function score at three and six month follow-up. Sensitivity analysis was performed for high quality studies and randomised studies.

RESULTS

Ten studies totalling 517 patients were included. Seven studies were randomised. All studies included patients who had failed conservative measures and excluded patients with systemic illness and other causes of foot pain. Studies reported outcomes using the visual analogue score (VAS) and American Orthopaedic Foot and Ankle Score (AOFAS). At 3-month follow-up, PRP injections were associated with improved VAS scores (standard mean difference [SMD], -0.66; 95% CI, -1.3 to -0.02; p = 0.04) and AOFAS scores (SMD, 1.87; 95% CI, 0.16-3.58; p = 0.03). At 6-month follow-up, there was no difference in VAS score (SMD, -0.66; 95% CI, -1.65 to 0.3; p = 0.17) or AOFAS scores (SMD, 1.69; 95% CI, -1.06 to 4.45; p = 0.23). No studies reported adverse event rates or cost analysis. There was no difference in pain or function score at one, six- or 12-month follow-up. Sensitivity analyses of high-quality studies showed no differences between the PRP and steroid group at any of the follow-up points.

CONCLUSIONS

PRP injections are associated with improved pain and function scores at three month follow-up when compared with corticosteroid injections. Information regarding relative adverse event rates and cost implications is lacking. Further, large-scale, high-quality, randomised controlled trials with blinding of outcome assessment and longer follow-up are required.

Evaluation of subcutaneous infiltration of autologous platelet-rich plasma on skin-wound healing in dogs

Platelet-rich plasma (PRP) is known to be rich in growth factors and cytokines, which are crucial to the healing process. This study investigate the effect of subcutaneous (S/C) infiltration of autologous PRP at the wound boundaries on wound epithelization and contraction. Five adult male mongrel dogs were used. Bilateral acute full thickness skin wounds (3 cm diameter) were created on the thorax symmetrically. Right side wounds were subcutaneously infiltrated with activated PRP at day 0 and then every week for three consecutive weeks. The left wound was left as control. Wound contraction and epithelization were clinically evaluated. Expression of collagen type I (COLI) A2, (COLIA2),histopathology and immunohistochemical (IHC) staining of COLI α1 (COLIA1) were performed on skin biopsies at first, second and third weeks. The catalase activity, malondialdehyde (MDA) concentration and matrix metalloproteinase (MMP) 9 (MMP-9) activity were assessed in wound fluid samples. All data were analysed statistically. The epithelization percent significantly increased in the PRP-treated wound at week 3. Collagen was well organized in the PRP-treated wounds compared with control wounds at week 3. The COLIA2 expression and intensity of COLIA1 significantly increased in PRP-treated wounds. MDA concentration was significantly decreased in PRP-treated wound at week 3. The catalase activity exhibited no difference between PRP treated and untreated wounds. The activity of MMP-9 reached its peak at the second week and was significantly high in the PRP-treated group. S/C infiltration of autologous PRP at the wound margins enhances the wound epithelization and reduces the scar tissue formation.