Effect of platelet‐rich plasma on degeneration change of rotator cuff muscles: In vitro and in vivo evaluations

Atrophy with fatty degeneration is often seen in rotator cuff muscles with torn tendons. PRP has been reported to enhance tissue repair processes after tendon ruptures. However, the effect of PRP on atrophy and fatty degeneration of the muscle is not yet known. The aim of this study is to examine the effect of PRP on degeneration change of rotator cuff muscles in vitro and in vivo. A murine myogenic cell line and a rat rotator cuff tear model were used in this study and PRP was administrated into subacromial space which is widely used in clinical practice. In in vitro study, administration of PRP to C2C12 cells stimulated cell proliferation while inhibited both myogenic and adipogenic differentiation. In in vivo study, administration of PRP suppressed Oil Red‐O positive lipid droplet formation. The expression of adipogenic genes was also decreased by PRP administration. In conclusion, PRP promoted proliferation of myoblast cells, while inhibiting adipogenic differentiation of myoblast cells and suppressing fatty degeneration change in rat torn rotator cuff muscles. Further investigations are needed to determine the clinical applicability of the PRP. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1806–1815, 2017.

     

Assessment of pain‐related behavior and pro‐inflammatory cytokine levels in the rat rotator cuff tear model

The cause of pain following rotator cuff tear has not been fully elucidated. The purpose of this study was to evaluate behavior and inflammatory cytokines in a rat unstabilized rotator cuff defect (UCD) model. Forty‐five Sprague–Dawley rats were divided into three groups: sham; UCD; and stabilized rotator cuff defect (SCD). Gait analysis was examined using CatWalk. Tumor necrosis factor (TNF)‐α, interleukin(IL)‐1β, and IL‐6 were measured within the subacromial bursa and the glenohumeral joint synovium at 21 and 56 days after surgery using an enzyme‐linked immunosorbent assay (ELISA). Stride length, print area and contact intensity in the UCD group was significantly lower than in the sham group after surgery. Stride length, print area and contact intensity in the SCD group was significantly higher than in the UCD group. In contrast, TNF‐α, IL‐1β, and IL‐6 in the UCD group was significantly higher than in the sham group at days 21 and 56. However, TNF‐α, IL‐1β, and IL‐6 in the SCD group was significantly lower than in the UCD group at days 21 and 56. The present results suggest that SCD is effective not only in improving shoulder function but also in reducing inflammatory cytokines, which may serve as one source of pain due to rotator cuff tear. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:286–290, 2014.     

Influence of the ratio of particulate autogenous bone graft/platelet‐rich plasma on bone healing in critical‐size defects: A histologic and histometric study in rat calvaria

The purpose of this study was to analyze histomorphometrically the influence of the ratio of particulate autogenous bone (AB) graft/platelet‐rich plasma (PRP) on bone healing in surgically created critical‐size defects (CSD) in rat calvaria. Fifty rats were divided into five groups: Group C (control), Group AB, Group AB/PRP‐50, Group AB/PRP‐100, and Group AB/PRP‐150. A 5‐mm diameter critical‐size defect was created in the calvarium of each animal. In Group C, the defect was filled by blood clot only. In Group AB, the defect was filled with 0.01 mL of AB graft. In Groups AB/PRP‐50, AB/PRP‐100, and AB/PRP‐150, the defects were filled with 0.01 mL of AB graft combined with 50, 100, and 150 µL of PRP, respectively. All animals were euthanized at 30 days postoperative. Histomorphometry, using image analysis software, and histology analyses were performed. New Bone Area (NBA) and the remaining bone graft particles area (RPA) were calculated as a percentage of the total area of the original defect. Percentage data were transformed into arccosine for analysis. No defect completely regenerated with bone. Group AB/PRP‐50 (41.78 ± 13.48%) had a significantly greater NBA than Groups C (19.29 ± 5.11%), AB (27.43 ± 10.90%) or AB/PRP‐150 (19.17 ± 8.45%) (p < 0.05). No significant differences were observed between groups AB/PRP‐50 and AB/PRP‐100 or among groups AB, AB/PRP‐100, and AB/PRP‐150 with regard to NBA (p > 0.05). Group AB/PRP‐150 (31.59 ± 3.22%) had a significantly greater RPA than Groups AB (19.09 ± 5.21%), AB/PRP‐50 (17.33 ± 4.43%), and AB/PRP‐100 (19.72 ± 3.62%) (p < 0.001). No significant differences were observed among groups AB, AB/PRP‐50, and AB/PRP‐100 with regard to RPA (p > 0.05). The ratio AB graft/PRP influences bone healing in surgically created CSD in rat calvaria. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:468–473, 2010     

Effect of tamoxifen on fatty degeneration and atrophy of rotator cuff muscles in chronic rotator cuff tear: An animal model study

Fatty degeneration of the rotator cuff muscles is an irreversible change resulting from chronic rotator cuff tear and is associated with poor clinical outcomes following rotator cuff repair. We evaluated the effect of Tamoxifen, a competitive estrogen receptor inhibitor, on fatty degeneration using a mouse model for chronic rotator cuff tear. Sixteen adult mice were divided into two diet groups (Tamoxifen vs. Regular) and subjected to surgical creation of a large rotator cuff tear and suprascapular nerve transection in their left shoulder with the right shoulder serving as a control. The rotator cuff muscles were harvested at 16 weeks and subjected to histology and RT‐PCR for adipogenic and myogenic markers. Histology showed substantially decreased atrophy and endomysial inflammation in Tamoxifen group, but no significant differences in the amount of intramuscular adipocytes and lipid droplets compared to the Regular group. With RT‐PCR, the operated shoulders showed significant upregulation of myogenin and PPAR‐γ, and downregulation of myostatin compared to the nonsurgical shoulder. No significant differences of gene expression were found between the two diet groups. Our study demonstrated that tamoxifen diet leads to decreased muscle atrophy and inflammatory changes following chronic rotator cuff tear, but has no apparent effect on adipogenesis. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1846–1853, 2015.     

Effect of highly purified capsaicin on articular cartilage and rotator cuff tendon healing: An in vivo rabbit study

Highly purified capsaicin has emerged as a promising injectable compound capable of providing sustained pain relief following a single localized treatment during orthopedic surgical procedures. To further assess its reliability for clinical use, the potential effect of highly purified capsaicin on articular cartilage metabolism as well as tendon structure and function warrants clarification. In the current study, rabbits received unilateral supraspinatus transection and repair with a single 1 ml injection of capsaicin (R + C), PEG‐only placebo (R + P), or saline (R + S) into the glenohumeral joint (GHJ). An additional group received 1 ml capsaicin onto an intact rotator cuff (I + C). At 18 weeks post‐op, cartilage proteoglycan (PG) synthesis and content as well as cell viability were similar (p > 0.05) across treatment groups. Biomechanical testing revealed no differences (p > 0.05) among tendon repair treatment groups. Similarly, histologic features of both cartilage and repaired tendons showed minimal differences across groups. Hence, in this rabbit model, a single injection of highly purified capsaicin into the GHJ does not induce a deleterious response with regard to cartilage matrix metabolism and cell viability, or rotator cuff healing. These data provide further evidence supporting the use of injectable, highly purified capsaicin as a safe alternative for management of postoperative pain following GHJ surgery. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1854–1860, 2015.     

Platelet-rich plasma versus corticosteroid injections in the management of patients with rotator cuff disease: A systematic review and meta-analysis

Platelet-rich plasma (PRP) is an alternative to corticosteroid (CS) injections in managing rotator cuff disease. This meta-analysis investigated differences between PRP and CS for function and pain scores in significance and minimal clinical important difference (MCID). A literature search of Ovid Cochrane Library, Medline, Embase, Epub, and Scopus was conducted from inception to October 28, 2021. Eligible studies reported patients older than 18 years with a diagnosis of rotator cuff disease. This review was registered in PROSPERO (ID: CRD42021278740). Twelve studies met eligibility criteria (n = 639) of patients receiving either PRP or CS. At short-term follow-up, a difference favored CS compared to PRP in baseline change for disability of arm, shoulder, and hand (DASH) score (MD = −5.08, 95% CI: −8.00, −2.15; p = 0.0007; I² = 0%) and simple shoulder test (SST) (MD = 1.25, 95% CI: 0.33, 2.18; p = 0.008; I² = 0%). At intermediate follow-up, a difference favored PRP to CS baseline change of the DASH score (MD = 3.41, 95% CI: 0.67, 6.15; p = 0.01; I² = 0%). At medium-term, a difference favored PRP to CS baseline change of the American Shoulder and Elbow Surgeons Shoulder (ASES) score (MD = −4.42, 95% CI: −8.16, −0.67; p = 0.02; I² = 0%). Both treatments achieved individual MCID for each score. Despite favoring CS at short-term follow-up and PRP at intermediate- and medium-term follow-up, functional and pain scores did not demonstrate any clinical difference between the two treatment modalities in management of rotator cuff disease at all follow-up periods.     

In vitro effects of glutamate and N‐methyl‐d‐aspartate receptor (NMDAR) antagonism on human tendon derived cells

It is known that extracellular glutamate concentrations are increased in tendinopathy but the effects of glutamate upon human tendon derived cells are unknown. The primary purpose was to investigate the effect of glutamate exposure on human tendon‐derived cells in terms of viability, protein, and gene expression. The second purpose was to assess whether NMDAR antagonism would affect the response of tendon‐derived cells to glutamate exposure. Human tendon‐derived cells were obtained from supraspinatus tendon tissue obtained during rotator cuff repair (tendon tear derived cells) and from healthy hamstring tendon tissue (control cells). The in vitro impact of glutamate exposure and NMDAR antagonism (MK‐801) was measured using the Alamar blue cell viability assay, immunocytochemistry, and quantitative real‐time PCR. Glutamate reduced cell viability at 24 h in tendon tear derived cells but not in control cells at concentrations of 7.5 mM and above. Cell viability was significantly reduced after 72 h of 1.875 mM glutamate in both cell groups; this deleterious effect was attenuated by NMDAR antagonism with 10 µM MK‐801. Both 24 and 72 h of 1.875 mM glutamate exposure reduced Type 1 alpha 1 collagen (COL1A1) and Type 3 alpha 1 collagen (COL3A1) gene expression, but increased Aggrecan gene expression. We propose that these effects of glutamate on tendon derived cells including reduced cell viability and altered matrix gene expression contribute to the pathogenesis of tendinopathy. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1515–1522, 2015.     

Platelet‐rich plasma protects rotator cuff‐derived cells from the deleterious effects of triamcinolone acetonide

Triamcinolone acetonide (TA) injections are widely used to treat enthesopathy, but they may induce adverse effects such as tendon impairment and rupture. Platelet‐rich plasma (PRP) is a blood fraction containing high platelet concentrations and various growth factors that play a role in tissue repair processes. The purpose of this study is to investigate whether TA has deleterious effects on human rotator cuff‐derived cells, and if PRP can protect these cells from the effects of TA. Human rotator cuff‐derived cells were cultured with and without TA and PRP, and the culture without any additive served as the control. Cell morphology was assessed at days 7 and 21. Cell viability was evaluated at days 1, 7, 14, and 21 by a water‐soluble tetrazolium salt assay. Induction of apoptosis was measured by immunofluorescence staining and flow cytometry at day 7. Induction of cleaved caspase‐3 was measured by immunofluorescence staining at day 7. The cells cultured with TA had a flattened and polygonal shape at day 7. The cells cultured with both TA and PRP were similar in appearance to control cells. Exposure to TA also significantly decreased cell viability, but cell viability did not decrease when PRP was added along with TA. The number of apoptotic cells increased with TA exposure, while addition of PRP prevented cell apoptosis. In conclusion, the deleterious effect of TA was prevented by PRP, which can be used as a protective agent for patients receiving local TA injections. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 976–982, 2013     

The effects of chronic unloading and gap formation on tendon‐to‐bone healing in a rat model of massive rotator cuff tears

The objective of this study was to understand the effect of pre‐repair rotator cuff chronicity on post‐repair healing outcomes using a chronic and acute multi‐tendon rat rotator cuff injury model. Full‐thickness dual tendon injuries (supra‐ and infraspinatus) were created unilaterally in adult male Sprague Dawley rats, and left chronically detached for 8 or 16 weeks. After chronic detachment, tears were repaired and acute dual tendon injuries were created and immediately repaired on contralateral shoulders. Tissue level outcomes for bone, tendon, and muscle were assessed 4 or 8 weeks after repair using histology, microcomputed tomography, biomechanical testing, and biochemical assays. Substantial gap formation was seen in 35% of acute repairs and 44% of chronic repairs. Gap formation negatively correlated with mechanical and structural outcomes for both healing time points regardless of injury duration. Bone and histomorphometry, as well as biomechanics, were similar between acute and chronic injury and repair regardless of chronicity and duration of healing. This study was the first to implement a multi‐tendon rotator cuff injury with surgical repair following both chronic and acute injuries. Massive tear in a rodent model resulted in gap formation regardless of injury duration which had detrimental effects on repair outcomes. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:439–447, 2014.     

Effects of platelet‐rich plasma on the healing of sternal wounds: A meta‐analysis

Sternal wound infection (SWI) is a devastating complication after cardiac surgery. Platelet‐rich plasma (PRP) may have a positive impact on sternal wound healing. A systematic review with meta‐analyses was performed to evaluate the clinical effectiveness of topical application of autologous PRP for preventing SWI and promoting sternal wound healing compared to placebo or standard treatment without PRP. Relevant studies published in English or Chinese were retrieved from the Cochrane Central Register of Controlled Trials (The Cochrane Library), PubMed, Ovid EMBASE, Web of Science, Springer Link, and the WHO International Clinical Trials Registry Platform (ICTRP) using the search terms “platelet‐rich plasma” and “sternal wound” or “thoracic incision.” References identified through the electronic search were screened, the data were extracted, and the methodological quality of the included studies was assessed. The meta‐analysis was performed for the following outcomes: incidence of SWI, incidence of deep sternal wound infection (DSWI), postoperative blood loss (PBL), and other risk factors. In the systematic review, totally 10 comparable studies were identified, involving 7879 patients. The meta‐analysis for the subgroup of retrospective cohort studies (RSCs) showed that the incidence of SWI and DSWI in patients treated with PRP was significantly lower than that in patients without PRP treatment. However, for the subgroup of randomized controlled trials (RCTs), there was no significant difference in the incidence of SWI or DSWI after intervention between the PRP and control groups. There was no significant difference in PBL in both RCTs and RSCs subgroups. Neither adverse reactions nor in‐situ recurrences were reported. According to the results, PRP could be considered as a candidate treatment to prevent SWI and DSWI. However, the quality of the evidence is too weak, and high‐quality RCTs are needed to assess its efficacy on preventing SWI and DSWI.     

The application of platelet‐rich plasma in the treatment of deep dermal burns: A randomized,double‐blind,intra‐patient controlled study

Platelet‐rich plasma (PRP) is a fraction of blood with a platelet concentration above baseline. When platelets get activated, growth factors involved in wound healing are released. The application of PRP has shown good results in wound care, however, up to date no substantial research has been performed on the effect of PRP in burn treatment. This randomized double blind intra‐patient controlled study investigates the effect of autologous PRP on wound healing in burns that require surgery with a meshed split skin graft (SSG). Fifty‐two patients with various areas of deep dermal to full thickness burns, receiving surgery with a SSG were included after informed consent. Comparable study areas A and B (intra‐patient) were appointed, randomized and either treated with a SSG and PRP or with a SSG alone. At day 5 to 7 postoperative, the epithelialization and graft take rate were assessed. Three, six, and twelve months postoperative, follow‐up measurements were performed in the form of POSAS‐questionnaires, DermoSpectroMeter, and Cutometer measurements. There was no statistically significant difference between the mean take rate nor the mean epithelialization rate at day 5–7 between the PRP‐treated and control areas. However, PRP‐treated wound areas showed more often better or equal epithelialization and take rates at day 5–7 than the standard treated areas. Minor effects were also seen in the reoperated and early operated subgroups. At 3, 6, and 12 months postoperative, POSAS scores from the patients and the observers, Dermaspectro‐, and Cutometer measurements did not depict a significant difference between the PRP and standard treated areas. Concluding, the addition of PRP in the treatment of burn wounds did not result in improved graft take and epithelialization, nor could we demonstrate better scar quality. There was, however, a considerable variation in our clinical population.     

Peripheral blood mononuclear cells enhance the anabolic effects of platelet‐rich plasma on anterior cruciate ligament fibroblasts

Use of platelet‐rich plasma (PRP) has shown promise in various orthopaedic applications, including treatment of anterior cruciate ligament (ACL) injuries. However, various components of blood, including peripheral blood mononuclear cells (PBMCs), are removed in the process of making PRP. It is yet unknown whether these PBMCs have a positive or negative effect on fibroblast behavior. To begin to define the effect of PBMCs on ACL fibroblasts, ACL fibroblasts were cultured on three‐dimensional collagen scaffolds for 14 days with and without PBMCs. ACL fibroblasts exposed to PBMCs showed increased type I and type III procollagen gene expression, collagen protein expression, and cell proliferation when the cells were cultured in the presence of platelets and plasma. However, addition of PBMCs to cells cultured without platelets had no effect. The increase in collagen gene and protein expression was accompanied by an increase in IL‐6 expression by the PBMCs with exposure to the platelets. Our results suggest that the interaction between platelets and PBMCs leads to an IL‐6 mediated increase in collagen expression by ACL fibroblasts. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:29–34, 2012