The use of platelet-rich plasma to treat chronic tendinopathies: A technical analysis

Microfracture surgery combined with platelet-rich plasma injection in treating osteochondral lesions of talus: A system review and update meta analysis

BACKGROUND

To systematically evaluate the efficacy of arthroscopic microfracture surgery combined with platelet-rich plasma (PRP) injection in treating osteochondral lesions of talus (OLT).

METHOD

A computer-based search of the PubMed, EMbase, Cochrane Library was developed. The search time was dated in December 2022. Randomized controlled trials and prospective case control studies comparing the treatment of OLT with microfracture surgery combined with PRP injection and microfracture surgery alone were included. The quality of the literatures were evaluated. Meta analysis was completed using the data of postoperative pain and function scores of the ankle joint reported in the literature.

RESULTS

Five randomized controlled trials with a total of 198 patients were included. Compared with microfracture surgery alone, meta-analysis showed that the postoperative visual analogue scale (VAS) score for ankle pain was significantly lower (P < 0.001), and the American Orthopaedic Foot and Ankle Society score (AOFAS) was significantly better ( P < 0.001) in the group of microfracture surgery combined with PRP injection. The change of VAS and AOFAS was also significantly better in the group of microfracture surgery combined with PRP injection (P < 0.001).

CONCLUSION

Arthroscopic microfracture surgery combined with PRP injection in treating OLT can significantly reduce pain and improve ankle function. More long-term follow-up, high-quality studies are needed.

LEVEL OF EVIDENCE

II.

Autologous i-PRF promotes healing of radiation-induced skin injury

Skin, as an exposed tissue, often suffers damage after exposure to radiotherapy and accidental events, which may lead to the formation of chronic refractory wounds. However, effective treatment options are usually limited for severe radiation-induced skin injury (RSI). Platelet-rich plasma (PRP) has been identified to promote wound healing, but whether a new generation of blood-derived biomaterial, injectable platelet-rich fibrin (i-PRF), is effective in repairing RSI remains unclear. In this study, blood was drawn from humans and Sprague-Dawley rats to prepare PRP and i-PRF, and the regenerative functions of PRP and i-PRF were investigated by exposing the dorsal skin of SD rats to local radiation (45 Gy) and exposing HDF-α cells and human umbilical vein endothelial cells (HUVECs) cells to X-rays (10 Gy). The healing effect of i-PRF on RSI was analysed by tube formation assay, cell migration and apoptosis assays, ROS assay, wound healing assay, histological characterisation and immunostaining. The results showed that exposure to high doses of radiation reduced cell viability, increased ROS levels and induced cell apoptosis, thereby causing dorsal trauma of rats. However, both PRP and i-PRF could resisted RSI, and they were capable of reducing inflammation and promoting angiogenesis and vascular regeneration. i-PRF has a higher concentration of platelets and platelet-derived growth factors, which has a more convenient preparation method and better repair effect and possesses a good application prospect for the repair of RSI.

Effects of leukocyte-rich platelet-rich plasma and leukocyte-poor platelet-rich plasma on the healing of bone-tendon interface of rotator cuff in a mice model

Platelet-rich plasma (PRP) is widely used clinically to treat tendon injuries, and often contains leukocytes. However, the debate regarding the concentration of leukocytes in PRP is still ongoing. This study aimed to evaluate the therapeutic effects of leukocyte-rich platelet-rich plasma (LR-PRP) and leukocyte-poor platelet-rich plasma (LP-PRP) on the healing of the bone-tendon interface (BTI) of the rotator cuff. A total of 102 C57BL/6 mice were used. Thirty mice were used to prepare the PRP, while 72 underwent acute supraspinatus tendon injury repair. The animals were then randomly assigned to three groups: LR-PRP, LP-PRP and control groups. The mice were euthanized at 4 and 8 weeks postoperatively, and histological, immunological and biomechanical analyses were performed. The histological results showed that the fusion effect at the bone-tendon interface at 4 and 8 weeks after surgery was greater in the PRP groups and significantly increased at 4 weeks; however, at 8 weeks, the area of the fibrocartilage layer in the LP-PRP group increased significantly. M2 macrophages were observed at the repaired insertion for all the groups at 4 weeks. At 8 weeks, M2 macrophages withdrew back to the tendon in the control group, but some M2 macrophages were retained at the repaired site in the LR-PRP and LP-PRP groups. Enzyme-linked immunoassay results showed that the concentrations of IL-1β and TNF-α in the LR-PRP group were significantly higher than those in the other groups at 4 and 8 weeks, while the concentrations of IL-1β and TNF-α in the LP-PRP group were significantly lower than those in the control group. The biomechanical properties of the BTI were significantly improved in the PRP group. Significantly higher failure load and ultimate strength were seen in the LR-PRP and LP-PRP groups than in the control group at 4 and 8 weeks postoperatively. Thus, LR-RPR can effectively enhance the early stage of bone-tendon interface healing after rotator cuff repair, and LP-PRP could enhance the later stages of healing after rotator cuff injury.

Update on Efficacy of Conservative Treatments for Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common upper extremity compression neuropathy. Non-operative interventions are usually the first-line treatments, and surgery is reserved for those that do not achieve a satisfactory symptom state by non-operative means. This narrative review summarizes the current evidence regarding the efficacy of orthoses, corticosteroid injections, platelet-rich plasma injections, Kinesio taping, neurodynamic techniques, gabapentin, therapeutic ultrasound, and extracorporeal shockwave therapy in people with CTS. While many trials suggest small short-term benefits, rigorous evidence of long-term patient-important benefits is limited. To improve the utility of healthcare resources, research in this area should focus on establishing efficacy of each treatment instead of comparing various treatments with uncertain benefits.

Enrichment of plasma in platelets and extracellular vesicles by the counterflow to erythrocyte settling

In order to prepare optimal platelet and extracellular vesicle (EV)-rich plasma for the treatment of chronic temporal bone inflammation, we studied effects of centrifugation parameters on redistribution of blood constituents in blood samples of 23 patients and 20 volunteers with no record of disease. Concentrations of blood cells and EVs were measured by flow cytometry. Sample content was inspected by scanning electron microscopy. A mathematical model was constructed to interpret the experimental results. The observed enrichment of plasma in platelets and EVs after a single spin of blood depended on the erythrocyte sedimentation rate, thereby indicating the presence of a flow of plasma that carried platelets and EVs in the direction opposite to settling of erythrocytes. Prolonged handling time correlated with the decrease of concentration of platelets and larger EVs in platelet and EV-rich plasma (PVRP), R = -0.538, p = 0.003, indicating cell fragmentation during the processing of samples. In further centrifugation of the obtained plasma, platelet and EV enrichment depended on the average distance of the sample from the centrifuge rotor axis. Based on the agreement of the model predictions with observations, we propose the centrifugation protocol optimal for platelet and EV enrichment and recovery in an individual sample, adjusted to the dimensions of the centrifuge rotor, volume of blood and erythrocyte sedimentation rate.[Figure: see text].

Evidence for the use of PRP in chronic midsubstance Achilles tendinopathy: A systematic review with meta-analysis

BACKGROUND

Platelet-rich plasma (PRP) injections have been proposed as an additional therapy in the treatment of chronic midsubstance Achilles tendinopathy (AT). The use of PRP injections as pharmacological treatment added to a conservative approach has gained growing interest, but the efficacy remains highly debated. The varying methodological quality of the available studies may contribute to these contradictory results. The aim of this systematic review with meta-analysis was to establish the existing evidence of PRP injections for chronic midsubstance AT on the functional outcome, with a risk of bias assessment of each included study.

METHODS

According to the PRISMA guidelines systematic searches were performed in Embase, the Cochrane library and Pubmed on June 12, 2020 for relevant literature. Only clinical trials comparing PRP injections with placebo, additional to an eccentric training program, in midsubstance AT were included. The primary outcome was Victorian Institute of Sport Assessment - Achilles (VISA-A) score at 3, 6 and 12 months post-injection. Risk of bias was assessed using the Cochrane risk-of-bias tool for randomized trials (Rob 2). As secondary outcome we assessed reported changes in tendon structure after PRP injections.

RESULTS

A total of 367 studies were identified with the initial database search. Finally, four randomized controlled trials (RCTs) met inclusion criteria for systematic review and meta-analysis with data of 170 patients available for pooling. Results showed no difference in clinical outcome between the PRP and placebo group at different points in time using the VISA-A score as outcome parameter (3 months 0.23 (CI -0.45, 0.91); 6 months 0.83 (CI -0.26, 1.92); 12 months 0.83 (CI -0.77, 2.44)). The bias analysis showed a low or intermediate risk of bias profile for all studies which supports the good methodological quality of each included article. Finally, it is unclear whether PRP injections cause an improvement in tendon structure. However, no direct relationship between tendon structure and clinical presentation of AT could be found.

CONCLUSION

PRP has no clear additional value in management of chronic midsubstance Achilles tendinopathy and therefore should not be used as a first-line treatment option.

Platelet-rich plasma protects human melanocytes from oxidative stress and ameliorates melanogenesis induced by UVB irradiation

To investigate the role of platelet-rich plasma (PRP) from different sources in alleviating oxidative stress and ameliorating melanogenesis in UVB-irradiated PIG1 cells, PIG1 cells were irradiated with 80 mJ/cm2 UVB prior to 1% PRP application and the following experiments were taken: the viability of UVB-irradiated PIG1 cells, cellular malondialdehyde (MDA) and reactive oxygen species (ROS) content, and activities of antioxidant enzymes. Western blotting was utilized to detect the expression level of proteins associated with melanin synthesis, apoptosis, and DNA lesions. We found that PRP intervention promoted cell proliferation, reduced MDA and ROS content, increased the activities of series of antioxidant enzymes, and alleviated DNA damages in UVB-damaged PIG1 cells. It is important to note that PRP treatment inhibited UVB-induced melanogenesis via the PI3K/Akt/GSK3β signal pathway. Therefore, we suppose PRP treatment exerts a protective role through their antioxidation effect on UVB-damaged PIG1 cells and hinders melanogenesis induced by UVB irradiation.

Platelet-Rich Plasma Applications for Achilles Tendon Repair: A Bridge between Biology and Surgery

Achilles tendon ruptures are very common tendon ruptures and their incidence is increasing in modern society, resulting in work incapacity and months off sport, which generate a need for accelerated and successful therapeutic repair strategy. Platelet-rich plasma (PRP) is emerging as adjuvant human blood-derived constructs to assist Achilles tendon rupture treatment. However, myriad PRP preparation methods in conjunction with poor standardization in the modalities of their applications impinge on the consistent effectiveness of clinical and structural outcomes regarding their therapeutic efficacy. The purpose of this review is to provide some light on the application of PRP for Achilles tendon ruptures. PRP has many characteristics that make it an attractive treatment. Elements such as the inclusion of leukocytes and erythrocytes within PRP, the absence of activation and activation ex vivo or in vivo, the modality of application, and the adjustment of PRP pH can influence the biology of the applied product and result in misleading therapeutic conclusions. The weakest points in demonstrating their consistent effectiveness are primarily the result of myriad PRP preparation methods and the poor standardization of modalities for their application. Selecting the right biological scaffold and applying it correctly to restitutio ad integrum of ruptured Achilles tendons remains a daunting and complex task.

The Anti-photoaging Effects of Pre- and Post-treatment of Platelet-rich Plasma on UVB-damaged HaCaT Keratinocytes

Platelet-rich plasma (PRP) has seen wide clinical use owing to its regenerative and repair abilities.

OBJECTIVE

To investigate the anti-photoaging effects of pre- and post-treatment of PRP on UVB-damaged HaCaT cells.

METHODS

HaCaT cells were irradiated with 80 mJ/cm² UVB, before or after PRP treatment (1000 × 10⁷ /L), and following measurements were taken: survival rate of UVB-irradiated HaCaT cells, malondialdehyde (MDA) content and activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT). Western blot was used to determine the effect of different PRP intervention on the expression of PI3K, AKT, ERK, MMP-1, MMP-9, TIMP-1 and γ-H2AX in the UVB-irradiated HaCaT cells.

RESULTS

pre- and post-PRP treatment reduced MDA content and increased the activities of GSH-Px, SOD and CAT in photoaged HaCaT cells. These changes resulted in reduced cytotoxic effects. Besides, different PRP intervention promoted cell proliferation via PI3K/AKT pathway. Furthermore, PRP application suppressed the expression of γ-H2AX. Also, PRP intervention alleviated photoaging effects by upregulating the expression level of tissue inhibitor of metalloproteinases-1 (TIMP-1) while downregulating matrix metalloproteinase (MMP) expression level in photoaged HaCaT cells.

CONCLUSION

pre- and post-PRP treatment play anti-photoaging role through strengthening cellular oxidative defense capacity, mitigating MMP expression, alleviating DNA damages and promoting proliferation of UVB-irradiated HaCaT cells.

Tennis elbow, study protocol for a randomized clinical trial: needling with and without platelet-rich plasma after failure of up-to-date rehabilitation

Background

The conservative management of lateral epicondylitis is known to be a difficult-to-treat annoying condition. A treatment with platelet-rich plasma (PRP) is often performed, but its efficacy remains controversial.

Methods

This study is a single-center, randomized double-blind controlled trial, preceded by a case series. All the 232 planned patients of the case series will undergo an up-to-date comprehensive rehabilitation program, including focused extracorporeal shock waves therapy. This rehabilitation program is expected to have a maximum success rate 75%. It is therefore aimed to allocate a minimum of 58 patients with rehabilitation failure into the 1:1 randomized trial. Stratification is planned on age and lesion pattern. The masking will be quadruple (Participant, Care Provider, Investigator & Outcome Assessor). The patients will undergo an ultrasound (US)-guided needling combined with either PRP (intervention group) or saline (control group). The primary endpoint will be the pain improvement from baseline (month 0) at 3 months on a 0–10 visual analog scale (VAS) during a maximal strength isometric contraction of the extensor carpialis brevis muscle. The main secondary endpoints will include the rehabilitation success rate and improvements from baseline at 3, 6, and 12 months of the following outcomes: (i) Single Assessment Numeric Evaluation (SANE) score, (ii) Patient-Rated Tennis Elbow Evaluation (PRTEE) score, (iii) maximal grip strength on Jamar test, and (iv) the ultrasonographic evaluation of the US of the epicondylar tendons.

Discussion

The study results will provide insight into the effect of PRP as adjuvant therapy to tendon fenestration, and may contribute to identify the best preceding and concomitant rehabilitation protocol.

Trial registration

ClinicalTrials.gov NCT03987256. Registered on 20 August 2019.

A possible injectable tissue engineered nucleus pulposus constructed with platelet-rich plasma and ADSCs in vitro

BACKGROUND

Injectable tissue engineered nucleus pulposus is a new idea for minimally invasive repair of degenerative intervertebral disc. The platelet-rich plasma (PRP) and adipose-derived stromal cells (ADSCs) could be harvested from autologous tissue easily. PRP contains numerous autologous growth factors and has reticulate fibrous structure which may have the potential to make ADSCs differentiate into nucleus pulposus-like cells. The goal of this study was to explore the feasibility of constructing a possible injectable tissue engineered nucleus pulposus with PRP gel scaffold and ADSCs.

METHODS

After identification with flow cytometry, the rabbit ADSCs were seeded into PRP gel and cultured in vitro. At the 2nd, 4th, and 8th week, the PRP gel/ADSCs complex was observed by macroscopy, histological staining, BrdU immunofluorescence, and scanning electron microscopy. The glycosaminoglycans (GAG) in the PRP gel/ADSCs complex were measured by safranin O staining with spectrophotometry. In PRP gel/ADSCs complex, gene expression of HIF-1α, aggrecan, type II collagen were tested by RT-PCR. The injectability of this complex was evaluated.

RESULTS

Macroscopically, the complex was solidified into gel with smooth surface and good elasticity. The safranin O dye was almost no positive staining at 2nd week; however, the positive staining of extracellular matrix was enhanced obviously at 4th and 8th week. The HE staining and SEM demonstrated that the cells were well-distributed in the reticulate scaffold. BrdU immunofluorescence showed that ADSCs can survive and proliferate in PRP gel at each time points. The level of GAG at 4th week was higher than those at 2nd week (P < 0.05), and significant difference was also noted between 4th and 8th week (P < 0.05). HIF-1α, aggrecan, type II collagen gene expression at 4th week were much more than those at 2nd week (P < 0.05), and significant differences were also noted between 4th and 8th week (P < 0.05). The flow rate of complex was 0.287 mL/min when passed through the 19-gauge needle with the 100 mmHg injection pressure.

CONCLUSIONS

Our preliminary findings suggest that the PRP gel make it possible for rabbit ADSCs differentiated into nucleus pulposus-like cells after coculture in vitro. According to the results, it is a better feasible method for construction of autologous injectable tissue engineered nucleus pulposus.

The conservative treatment of longstanding adductor-related groin pain syndrome: a critical and systematic review

Longstanding (chronic) adductor-related groin pain syndrome is a widely common problem for athletes in many sports activities which often drastically reduces player activity and performance. The first choice in therapeutic treatment is conservative therapy. The objective of this study is to provide a systematic review regarding conservative treatment for longstanding adductor-related groin pain syndrome present in literature today. Furthermore, this study aims to give a critical vision of the current state of the art of the considered topic. After screening 234 articles, 19 studies following the inclusion criteria were included and summarized in this current systematic review and seven different types of therapeutic interventions were described. Compression clothing therapy, manual therapy together with strengthening exercise and prolotherapy were the therapeutic interventions which showed both the greatest level of strength of evidence (Moderate) and grade of recommendation (D). The remaining four types of therapeutic interventions i.e.: corticoid injection, platelet rich plasma therapy, intra-tissue percutaneous electrolysis and pulse-dose radiofrequency, showed both lower levels of strength of evidence (Conflicting) and grade of recommendation (C). In conclusion the literature available on the conservative treatment for longstanding adductor-related groin pain syndrome is limited and characterized by a low level of evidence. Therefore, our recommendation is to refer only to the few studies with higher level of evidence and at the same time to encourage further research in this area. The intervention showing the greater level of strength of evidence, and the greater grade of recommendation are compression clothing therapy, manual therapy and strengthening exercise, and prolotherapy. Other therapeutic interventions such as intra-tissue percutaneous electrolysis and pulse-dose radiofrequency seem promising but require further studies to confirm their efficacy.

Efficacy of a Semi Automated Commercial Closed System for Autologous Leukocyte- and Platelet-Rich Plasma (l-prp) Production in Dogs: A Preliminary Study

BACKGROUND

To characterize the cellular composition (platelets, erythrocytes, and leukocytes) and determine platelet-derived growth factor isoform BB (PDGF-BB) concentration in canine leukocyte- and platelet rich plasma (L-PRP) produced using a commercial semi-automated closed system.

METHODS

Twenty milliliters of citrated whole blood were obtained from 30 healthy un-sedated canine blood donors and processed using a semi-automated completely closed commercial system (CPUNT 20, Eltek group, Casale Monferrato, Alessandria, Italy) according to the manufacturer's instructions. Erythrocyte, leukocyte, and platelet counts were determined in both whole blood (WB) and resultant L-PRP. The PDGF-BB concentration was evaluated after bovine thrombin activation of 10 L-PRP samples.

RESULTS

This commercial system produced on average 2.3 ± 0.7 mL of L-PRP containing a high concentration of platelets (767,633 ± 291,001 μL, p < 0.001), with a 4.4 fold increase in platelet count, lower concentration of erythrocytes (528,600 ± 222,773 μL, p < 0.001) and similar concentration of leukocytes (8422 ± 6346 μL, p = 0.9918) compared with WB. L-PRP had an average of 3442 ± 2061 pg/mL of PDGF-BB after thrombin activation. Neutrophils, lymphocytes and monocytes average percent content in L-PRP was 14.8 ± 13.2, 71.7 ± 18.5 and 10.7 ± 6.4, respectively.

CONCLUSION

Sterile canine L-PRP prepared using this semi-automated closed system is easy to obtain, produces a significant increase in platelet count compared to WB and contains a detectable concentration of PDGF-BB after activation. Additional in vitro and in vivo studies are needed to assess inflammatory markers concentration and the therapeutic efficacy of this L-PRP in dogs.

The effects of aging, diabetes mellitus, and antiplatelet drugs on growth factors and anti-aging proteins in platelet-rich plasma

As the aged population continues to markedly increase worldwide, the incidences of diabetes mellitus (DM) and cardiovascular disease (CVD) are increasing. In this study, we investigated the effects of aging, DM, and antiplatelet drugs on growth factors and anti-aging proteins in platelet-rich plasma (PRP). The study participants were classified into the following four groups: Group A, healthy individuals aged ≤45 years; Group B, healthy individuals aged >45 years; Group C, DM patients aged >45 years; and Group D, CVD patients aged >45 years taking antiplatelet drugs. The concentrations of epidermal growth factor (EGF), fibroblast growth factor (FGF)-2, platelet-derived growth factor (PDGF)-AA, PDGF-AB/BB, vascular endothelial growth factor (VEGF)-A, tissue inhibitor of metalloproteinase 2 (TIMP2), insulin-like growth factor 1 (IGF-1), growth differentiation factor (GDF)11, and clusterin in PRP samples were determined to analyze the effects of aging, DM, and antiplatelet drugs. Overall, the concentrations of IGF-1, TIMP2, and clusterin did not vary significantly between the four groups. The concentrations of PDGF-AB/BB (P = 0.010), VEGF-A (P = 0.000), and GDF11 (P = 0.026) were significantly different between Group A and Group B. Further, the concentrations of EGF (P = 0.000) and GDF11 (P = 0.000) were significantly different between Groups B and C. The concentrations of EGF (P = 0.001), VEGF-A (P = 0.000), and GDF11 (P = 0.002) significantly differed between Groups A and C. The concentrations of FGF-2 (P = 0.048), PDGF-AA (P = 0.03), and GDF11 (P = 0.001) were significantly different between Groups B and D. The concentrations of PDGF-AB/BB (P = 0.032), VEGF-A (P = 0.010), and GDF11 (P = 0.02) significantly differed between Groups A and D. We found that PRP contains high concentrations of the growth factors, TIMP2 and GDF11. Aging, DM, and antiplatelet drugs can decrease the concentration of some growth factors and GDF11, which weakens the regenerative capacity and anti-aging effects of PRP and reduces the quality of PRP.