[Comparative study of five techniques of preparation of platelet-rich plasma]

Narrowband ultraviolet B phototherapy combined with intralesional injection of either latanoprost or platelet-rich plasma for stable nonsegmental vitiligo

BACKGROUND

Narrowband ultraviolet B (NB-UVB) phototherapy is the cornerstone of vitiligo treatment. Its combination with other treatments usually yields a better response. Latanoprost, a prostaglandin F2α analog, and autologous platelet-rich plasma (PRP) have been reported to be effective for vitiligo.

AIM

To evaluate the efficacy of NB-UVB combined with intralesional latanoprost or PRP for stable nonsegmental vitiligo (NSV).

METHODS

Sixty patients with stable NSV were recruited and randomly allocated to two equal groups. NB-UVB phototherapy was administered twice a week for all patients. Additionally, group A received intralesional latanoprost injections once weekly, while group B received intralesional autologous PRP injections every 2 weeks.

RESULTS

At 24 weeks, excellent repigmentation response was observed in 26.7% and 13.3% of patients in the latanoprost/NB-UVB and PRP/NB-UVB groups, respectively, with no significant difference in degrees of repigmentation between the two groups. However, the Vitiligo Extent Score for a Target Area (VESTA) score was significantly higher in the latanoprost/NB-UVB group (p = .032). Moreover, lesions located on nonacral skin responded significantly better than those on acral skin. Only erythema was significantly higher in the PRP/NB-UVB group, while the recurrence of depigmentation was significantly higher in the latanoprost/NB-UVB group.

CONCLUSIONS

Both latanoprost and PRP have the potential to be effective add-on therapies to NB-UVB phototherapy for stable NSV, with latanoprost resulting in a greater repigmentation response and PRP producing a more stable response.

SAS-PRP Study: A Real-Life Satisfaction Assessment in Patients with Cartilage Lesions of the Knee Treated by Platelet-Rich Plasma

Platelet-rich plasma (PRP) is a rising therapy treating locomotor system lesions such as knee osteoarthritis. The objective of this study was to evaluate patients' satisfaction 6 to 12 months after a PRP injection for cartilage lesions of their knee under real-life conditions. Patients' satisfaction was assessed by a specific questionnaire named SATMED-Q©, which explores six different dimensions of a given treatment. In addition, pain and function were assessed thanks to VAS pain, WOMAC, and IKDC scores. Responders were identified through the OMERACT-OARSI criteria. We observed excellent satisfaction after a PRP injection with a SATMED-Q© score of 80.81% 6 to 12 months after the procedure. Even when there was no significant improvement in pain and function scores, 52% of the evaluated population fulfilled the OMERACT-OARSI criteria and were considered responders. According to the sub-group analysis, patients with less osteoarthritis damage (i.e., Kellgren-Lawrence grades 1-2) and older study subjects (i.e., >40 years old) with focal chondropathy had benefited most from their PRP injection. Thus, platelet-rich plasma seems to be a well-tolerated and efficient therapy for cartilage lesions of the knee.

Multiple platelet-rich plasma injections are superior to single PRP injections or saline in osteoarthritis of the knee: the 2-year results of a randomized, double-blind, placebo-controlled clinical trial

INTRODUCTION

The primary purposes of this study were to prove the efficacy of PRP injection therapy on knee pain and functions by comparing patients with mild to moderate OA with a placebo control group, and also to understand the effectiveness of multiple doses compared to a single dose. It was hypothesized that PRP would lead to more favorable results than the placebo at 1, 3, 6, 12 and 24 months after treatment.

MATERIALS AND METHODS

237 patients diagnosed with OA were randomly separated into 4 groups, who were administered the following: single dose of PRP (n: 62), single dose of sodium saline (NS) (n: 59), three doses of PRP (n: 63), and three doses of NS (n: 53). Clinical evaluations were made pre-treatment and at 1, 3, 6, 12 and 24 months post-treatment, using the Knee Injury and Osteoarthritis Result Score (KOOS), Kujala Patellofemoral Score, knee joint range of motion (ROM), measurements of knee circumference (KC), and mechanical axis angle (MAA) and a Visual Analog Scale (VAS) for the evaluation of pain.

RESULTS

The better score values in the groups were recorded at 3 and 6 months. Patients treated with PRP maintained better scores at 3, 6 and 12 months compared to the NS groups (p < 0.05). Multiple doses of PRP were seen to be more effective than single-dose PRP at 6 and 12 months (p < 0.05). At the end of 24 months, there was no significant score difference across all the groups. The most positive change in scores was found in stage 2 OA, and the most positive change in ROM was in stage 3 OA patients. In the PRP groups, KC decreased more at 1 and 6 months (p < 0.05). Compared to other age groups, patients aged 51-65 years scored better at 6 months (p < 0.05). A negative correlation was determined with MAA scores (r = - 0.508, p < 0.001).

CONCLUSION

In comparison to the placebo (NS), leukocyte-rich PRP treatment was determined to be effective in the treatment of OA. Multiple doses of PRP increase the treatment efficacy and duration. Of all the patients treated with PRP, the best results were obtained by patients aged 51-65 years, with lower MAA, and by K/L stage 2 OA patients.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

REGISTRATION

NCT04454164 (ClinicalTrials.gov identifier).

Clinical Cohort Study in Canine Patients, to Determine the Average Platelet and White Blood Cell Number and Its Correlation with Patient's Age, Weight, Breed and Gender: 92 Cases (2019-2020)

Due to its easy preparation and that it is well tolerated, the use of autologous platelet-rich plasma (PRP) has become increasingly popular in regenerative medicine. However, there are still no clear guidelines on how it should be classified or whether the individual canine patient’s clinical status can influence its quality. Objective: This study aims to show if the weight, age, sex, neutered status or breed of canine patients have any correlation with the composition of PRP. Design: A blinded count of the platelets and white blood cells (WBC) was performed from 111 samples from 92 client owned dogs undergoing treatment for degenerative joint disease (DJD). The results were analysed using Pearson correlation test, ANOVA test or Student T-test. Results: There is a positive correlation between the number of platelets and WBC in canine patients of different breeds, but there was no significant difference on the platelet number and WBC number among the different breeds. The weight of the patient is also directly correlated to the platelet number (p = 0.003) but not WBC number. WBC number was negatively correlated to the weight of the patient. The sex and age of the patient did not affect platelets and WBC number, although WBC number is increased in non-neutered male population (p = 0.003). However, it would be interesting to investigate whether the growth factors released from the platelet granules are affected by patient variables in a canine population. Conclusions: Our results show that it is possible to obtain good quality autologous PRP, irrespective of age, sex, neutered status or weight of the patient, for PRP regenerative therapy.

The platelet-rich plasma lysate use in the treatment of persistent epithelial defects after keratoplasty

AIM:to evaluate the effectiveness of the platelet-rich plasma lysate (PRP lysate) use in the treatment of persistent epithelial defects (PED) after keratoplasty. MATERIALS AND METHODS:In the study, 60 patients with PED after keratoplasty were included. The 1st group (24 cases)included patients after keratoplasty with low risk of rejection, and the 2nd group 36 cases after keratoplasty with highrisk of rejection. Each group was divided into two subgroupscontrol subgroups 1a (cases 10) and 2a (cases 16), where patients received only standard postoperative therapy, and the main subgroups 1b (cases 14) and 2b (cases 20), in which PRP lysate was prescribed against the background of standard therapy, starting from the Day 15 post-op. As the criterion for effective treatment, complete persistent epithelialization after keratoplasty was considered. RESULTS:The effectiveness of the use of PRP lysate in the subgroup 1b was 85.7%, while complete epithelialization in the control subgroup 1a was recorded in 70%; in the subgroup 2b, complete epithelialization was observed in 55%, in the control subgroup 2ain 43.75%. CONCLUSION:The use of PRP lysate in the treatment of PED after corneal transplantation as an adjuvant therapy is effective and safe in both high and low risk keratoplasty. In the examined category of patients, treatment with blood derivatives increases the frequency and rate of complete epithelialization.

Autologous Platelet-Rich Plasma Efficacy in the Field of Regenerative Medicine: Product and Quality Control

Platelet-rich plasma (PRP) has emerged as a significant regenerative therapy used alone or combined mainly with stem cells, autologous fat grafts, hyaluronic acid, and biomaterials in a variety of medical fields, especially in hair regrowth, wound healing, and sports and rehabilitation medicine. However, the results obtained with this biologic therapy are heterogeneous and conflicting. The observed disparities in the effectiveness of PRP therapies may be due to a lack of standardization in blood processing and preparation. This article is aimed at reviewing the main biological parameters that need to be documented for a thorough reporting of quantitative and qualitative characteristics of the PRP injected, to allow a comparison between the quality of samples and the clinically obtained results and advance the efforts towards treatment standardization.

Combined platelet-rich plasma and cold water immersion treatment minimize the damage following a skeletal muscle stretch injury in rats

The skeletal muscle stretch injuries are commonly observed in sports. In order to stimulate tissue healing, the platelet-rich plasma (PRP) and cold water immersion (CWI) are widely used in clinical practice. This study investigated the effects of isolated or combined PRP and/or CWI on the oxidative damage determined by a stretch injury induced in gastrocnemius muscle of rats. PRP and CWI are applied immediately after the injury, and the biochemical analysis was performed after 1, 3, 5, or 7 days. The levels of o thiobarbituric acid reactive substances and oxidized dichlorofluorescein were significantly increased, both in skeletal muscle tissue and erythrocytes preparations, and the combined PRP and CWI minimized these parameters. Moreover, combined PRP and CWI were more effective than the isolated treatments to increase catalase activity, also the ratio of reduced/oxidized glutathione, and the non-protein thiols (-SH) group levels. In conclusion, we could infer that the combination of these regular treatments used in an isolated form shows a great potential for treatments of muscular injuries.

Technical and biological review of authorized medical devices for platelets-rich plasma preparation in the field of regenerative medicine

Platelet-rich plasma (PRP) has seen increased interest and utilization over the past decade, particularly in the field of musculoskeletal disease. This growth has been accompanied by the development of medical devices to realize PRP preparation which includes blood collection, centrifugation, and PRP isolation. The final PRP composition is directly influenced by this preparation step and absence of biological quality control led to a lack of comparability between PRP products that could explain the large variability in the clinical benefit of PRP reported in literature. To circumvent this issue, the scientific community developed different PRP classifications but none of them have been adopted. The goal of this review is to furnish both technical and biological characteristics from PRP commercial systems. On review of 1379 studies, 105 studies were selected according to inclusion criteria for technical analysis and led to the identification of 50 commercial systems that have been classified in three technical categories based on the blood harvesting technique (tubes, syringes or bags). Twelve studies were selected and sufficiently describe biological characteristics from only 14 commercial systems from the 50 identified in the technical analysis. Inclusion of duplicates characterization from a same PRP system lead to the final analysis of 36 PRP preparations that met the inclusion criteria of the biological analysis. All these PRP preparations have been classified among the seven existing classifications. Comparison from all biological parameters and classifications revealed a large heterogeneity among the available current PRP commercial systems. Index of biological sensitivity of classifications to distinguish PRP preparations were also variable. Although these findings should help clinicians in selecting a system that meets their specific needs, this also raises the question to standardize the parameters to biologically define PRP preparation among users and to systematically performed PRP qualification when used.

Alternative and complementary therapies in osteoarthritis and cartilage repair

Osteoarthritis (OA) is the most common joint condition and, with a burgeoning ageing population, is due to increase in prevalence. Beyond conventional medical and surgical interventions, there are an increasing number of ‘alternative’ therapies. These alternative therapies may have a limited evidence base and, for this reason, are often only afforded brief reference (or completely excluded) from current OA guidelines. Thus, the aim of this review was to synthesize the current evidence regarding autologous chondrocyte implantation (ACI), mesenchymal stem cell (MSC) therapy, platelet-rich plasma (PRP), vitamin D and other alternative therapies. The majority of studies were in knee OA or chondral defects. Matrix-assisted ACI has demonstrated exceedingly limited, symptomatic improvements in the treatment of cartilage defects of the knee and is not supported for the treatment of knee OA. There is some evidence to suggest symptomatic improvement with MSC injection in knee OA, with the suggestion of minimal structural improvement demonstrated on MRI and there are positive signals that PRP may also lead to symptomatic improvement, though variation in preparation makes inter-study comparison difficult. There is variability in findings with vitamin D supplementation in OA, and the only recommendation which can be made, at this time, is for replacement when vitamin D is deplete. Other alternative therapies reviewed have some evidence (though from small, poor-quality studies) to support improvement in symptoms and again there is often a wide variation in dosage and regimens. For all these therapeutic modalities, although controlled studies have been undertaken to evaluate effectiveness in OA, these have often been of small size, limited statistical power, uncertain blindness and using various methodologies. These deficiencies must leave the question as to whether they have been validated as effective therapies in OA (or chondral defects). The conclusions of this review are that all alternative interventions definitely require clinical trials with robust methodology, to assess their efficacy and safety in the treatment of OA beyond contextual and placebo effects.

Platelet-Rich Plasma and Stem Cells for Hair Growth: A Review of the Literature

The prevalence of hair loss, its psychological consequences, and historically subpar treatments present a unique challenge to the physician. The current Food and Drug Administration-approved treatments for hair loss are plagued by ineffectiveness, noncompliance, and adverse effects. Recent advances in our understanding of hair physiology have fueled the development of more efficacious, minimally invasive, and safer treatment options for hair restoration including plasma-rich protein and stem cell therapy. Platelet-rich plasma, the autologous preparation of concentrated platelets in plasma, when injected into the scalp of patients with both androgenetic alopecia (AGA) and alopecia areata (AA), has been shown to increase hair count and density. The clinical findings have been supported by histologic evaluation of the scalp skin. These findings have been recapitulated in numerous randomized controlled trials. Stem cell therapy, although newer in its application in hair restoration, has also been effective for treating both AGA and AA. The isolation techniques for stem cells are varied, but regardless have shown promising results in early prospective and retrospective studies.

Photoaging Skin Therapy with PRP and ADSC: A Comparative Study

BACKGROUND

Stem cells from adipose tissue (ADSCs) and platelet-rich plasma (PRP) are innovative modalities that arise due to their regenerative potential.

OBJECTIVE

The aim of this study was to characterize possible histological changes induced by PRP and ADSC therapies in photoaged skin.

METHODS

A prospective randomized study involving 20 healthy individuals, showing skin aging. They underwent two therapeutic protocols (protocol 1: PRP; protocol 2: ADSCs). Biopsies were obtained before and after treatment (4 months).

RESULTS

PRP protocol showed unwanted changes in the reticular dermis, mainly due to the deposition of a horizontal layer of collagen (fibrosis) and elastic fibers tightly linked. Structural analyses revealed infiltration of mononuclear cells and depot of fibrotic material in the reticular dermis. The ADSC protocol leads to neoelastogenesis with increase of tropoelastin and fibrillin. There was an improvement of solar elastosis inducing an increment of macrophage polarization and matrix proteinases. These last effects are probably related to the increase of elastinolysis and the remodeling of the dermis.

CONCLUSIONS

The PRP promoted an inflammatory process with an increase of reticular dermis thickness with a fibrotic aspect. On the other hand, ADSC therapy is a promising modality with an important antiaging effect on photoaged human skin.

Review of concentration yields in commercially available platelet-rich plasma (PRP) systems: a call for PRP standardization

Platelet-rich plasma (PRP) has become increasingly popular in pain medicine with hopes of becoming a safe, effective alternative to routine treatments. However, given its autologous nature, PRP injectate may differ depending on the specific manufacturer and protocol. Currently, there is no standardization of reporting protocol. This systematic review compiles and standardizes values on PRP preparation and final product composition of platelets, white cell count, and growth factors for ease of comparison. On review of 876 studies, 13 studies were selected according to our inclusion criteria. Data from 33 PRP systems and protocols were extracted and standardized. Overall, PRP final product concentrations as well as PRP preparation protocols varied widely between systems. However, platelet concentration was directly correlated with both volume of blood collected and device centrifugal force. In conclusion, there is a large heterogeneity between PRP separation systems that must be resolved for proper study of this promising treatment.

Autologous Conditioned Plasma for tendon healing following arthroscopic rotator cuff repair. Prospective comparative assessment with magnetic resonance arthrography at 6 months' follow-up

INTRODUCTION

Despite improvements in technique and materials for rotator cuff repair, mean re-tear rates remain close to 30%. The aim of the present study was to assess injection of Autologous Conditioned Plasma (ACP™, Arthrex) for tendon healing after arthroscopic repair. The study hypothesis was that ACP™ improves the tendon-healing rate.

MATERIAL AND METHOD

A non-randomized comparative prospective study included all patients aged over 18 years operated on in 2010 for arthroscopic repair of full-thickness rotator cuff tear with≤2 fatty degeneration on the Goutallier classification, whatever the severity of retraction, on virgin non-osteoarthritic shoulder without contraindications for magnetic resonance (MR) arthrography. The surgical protocol was standardized. The first half of the patient sample received end-of-procedure ACP™ injection to the repaired tendon, tuberosity freshening surface and subacromial space, and the second (control) half received no supplementary treatment. The main endpoint was tendon healing on MR arthrography at 6 months according to Sugaya. Secondary endpoints comprised shoulder pain at rest on a numerical scale (0=no pain to 10=worst imaginable pain) and Constant functional score.

RESULTS

Two of the 58 patients refused MR arthrography and 7 were lost to follow-up. Forty-nine patients (26 ACP™, 23 controls) were analyzed: 20 male, 29 female; mean age, 61±7.3 years. There were no significant intergroup differences in healing rate at 6 months (ACP™ 73.1% vs. 78.3% controls; p=0.75), shoulder pain (2±1.8 vs. 2.6±1.7, respectively; p=0.24), or Constant score (77±13.5/100 vs. 72.4±12.3, respectively; p=0.18).

CONCLUSION

Associating ACP™ did not improve healing after arthroscopic rotator cuff repair. Sample size, however, had been calculated for a large expected difference, leading to lack of power.

LEVEL OF EVIDENCE

III; case-control study.

Concentrations of Blood Components in Commercial Platelet-Rich Plasma Separation Systems: A Review of the Literature

BACKGROUND

Platelet-rich plasma (PRP) has proven to be a very safe therapeutic option in the treatment of tendon, muscle, bone, and cartilage injuries. Currently, several commercial separation systems are available for the preparation of PRP. The concentrations of blood components in PRP among these separation systems vary substantially.

PURPOSE

To systematically review and evaluate the differences between the concentrations of blood components in PRP produced by various PRP separation systems.

STUDY DESIGN

Systematic review.

METHODS

MEDLINE/PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE were searched for studies that compared the concentrations of blood components and growth factors in PRP between various separation systems and studies that reported on the concentrations of blood components and growth factors of single separation systems. The primary outcomes were platelet count, leukocyte count, and concentration of growth factors (eg, platelet-derived growth factor-AB [PDGF-AB], transforming growth factor-β1 [TGF-β1], and vascular endothelial growth factor [VEGF]). Furthermore, the preparation protocols and prices of the systems were compared.

RESULTS

There were 1079 studies found, of which 19 studies were selected for inclusion in this review. The concentrations of platelets and leukocytes in PRP differed largely between, and to a lesser extent within, the studied PRP separation systems. Additionally, large differences both between and within the studied PRP separation systems were found for all the growth factors. Furthermore, preparation protocols and prices varied widely between systems.

CONCLUSION

There is a large heterogeneity between PRP separation systems regarding concentrations of platelets, leukocytes, and growth factors in PRP. The choice for the most appropriate type of PRP should be based on the specific clinical field of application. As the ideal concentrations of blood components and growth factors for the specific fields of application are yet to be determined for most of the fields, future research should focus on which type of PRP is most suitable for the specific field.

Effects of Allogeneic Platelet-Rich Plasma (PRP) on the Healing Process of Sectioned Achilles Tendons of Rats: A Methodological Description

This article describes the experimental procedures used to observe if PRP can positively affect tendon healing. There are 4 main steps to follow: induce a lesion in the Achilles tendon; prepare PRP and inject it (or the saline solution); remove the tendon; and perform biomechanical, molecular, and histological evaluations. At each step, all the procedures and methods are described in detail, so they can be reproduced easily. Achilles tendons have been surgically sectioned (removal of a 5-mm long section). Afterwards, PRP or saline solution was injected to study whether PRP has a positive effect on the healing of the tendon. Three groups of 40 animals (a total of 120 rats were used in this study) were subdivided into 2 subgroups: PRP injection group and a saline injection control group. Rats were sacrificed at increasing time points (Group A: 5 days; Group B: 15 days; Group C: 30 days) and tendons were removed. 90 tendons underwent biomechanical testing before performing transcriptomic analysis and the 30 remaining tendons were submitted to histological analysis.

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

Platelet-rich plasma (PRP) is blood plasma with a high concentration of autologous platelets which constitute an immense reservoir of growth factors. The clinical use of PRP is widespread in various medical applications. Although highly popular with athletes, the use of PRP for the treatment of tendinopathies remains scientifically controversial, particularly due to the diversity of products that go by the name of "PRP." To optimize its use, it is important to look at the various stages of obtaining PRP. In this literature review, we take a closer look at eight parameters which may influence the quality of PRP: 1) anticoagulants used to preserve the best platelet function, 2) the speed of centrifugation used to extract the platelets, 3) the platelet concentrations obtained, 4) the impact of the concentration of red and while blood cells on PRP actions, 5) platelet activators encouraging platelet degranulation and, hence, the release of growth factors, and 6) the use or nonuse of local anesthetics when carrying out infiltration. In addition to these parameters, it may be interesting to analyze other variables such as 7) the use of ultrasound guidance during the injection with a view to determining the influence they have on potential recovery.

Eccentric Training for Tendon Healing After Acute Lesion: A Rat Model

BACKGROUND

The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore, eccentric exercise seems to improve the mechanical quality of the tendon.

HYPOTHESIS

A combination of PRP injection and eccentric training might be more effective than either treatment alone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Adult male rats were anesthetized, an incision was performed in the middle of their left patellar tendon and an injection of physiological fluid (PF) or homologous PRP was randomly made at the lesion level. The rats were then divided into 2 groups: the eccentric group, undergoing eccentric training 3 times a week, and the untrained group, without any training. Thus, 4 groups were compared. After 5 weeks, the tendons were removed and their ultimate tensile strength and energy were measured. Tendons were frozen for proteomic analyses when all biomechanical tests were completed. Statistical analysis was performed with linear mixed effect models.

RESULTS

No significant difference was found between the treatments using PF injection or PRP injection alone. However, the value of the ultimate tensile force at rupture was increased by 4.5 N (108% of control, P = .006) when eccentric training was performed. An intragroup analysis revealed that eccentric training significantly improved the ultimate force values for the PRP group. Proteomic analysis revealed that eccentric training led to an increase in abundance of several cytoskeletal proteins in the PF group, while a decrease in abundance of enzymes of the glycolytic pathway occurred in the PRP-treated groups, indicating that this treatment might redirect the exercise-driven metabolic plasticity of the tendon.

CONCLUSION

Eccentric training altered the metabolic plasticity of tendon and led to an improvement of injured tendon resistance regardless of the treatment injected (PF or PRP).

CLINICAL RELEVANCE

This study demonstrates the necessity of eccentric rehabilitation and training in cases of tendon lesion regardless of the treatment carried out.

Optimisation of platelet concentrates therapy: Composition, localisation, and duration of action

Platelet concentrates (PC) generally refers to a group of products that are prepared from autologous blood intended to enhance healing activities. PC therapy is now very popular in treating musculoskeletal injuries; however, inconsistent clinical results urge the need to understand the working mechanism of PC. It is generally believed that the platelet-derived bioactive factors are the active constituents, and their bioavailability in the vicinity of the lesion sites determines the treatment efficacies. Therefore, the composition, localisation, and duration of the action of PC would be key determinants. In this review, we discuss how different preparations and delivery methods of PC would affect the treatment outcomes with respect to clinical evidence about PC therapy for osteoarthritis, tendinopathies, rotator cuff tears, anterior cruciate ligament injuries, and bone fractures. This review can be used as a quick guide for the use of PC therapy and provide insights for the further optimisation of the therapy in the near future.

Platelet-rich plasma reduces the oxidative damage determined by a skeletal muscle contusion in rats

Platelet-rich plasma (PRP) has received increasing attention and is widely used in clinical practice in order to stimulate human tissue healing. Contusions are very common injuries observed in sports and affect the function of the musculoskeletal system. This study investigated the effects of PRP on the oxidative damage determined by a contusion induced in gastrocnemius muscle of rats. PRP was injected intramuscularly immediately after injury and every 48 h, and the biochemical analysis was performed 1, 3, 5, or 7 days after the contusion onset in order to evaluate the changes characteristics of the healing process. The contusion increased the levels of oxidative stress markers such as thiobarbituric acid reactive substances and oxidized dichlorofluorescein both in skeletal muscle tissue and erythrocytes preparations, and PRP treatment significantly reduced these oxidative damage markers. Furthermore, the contusion decreased the cellular viability in the site of the lesion and PRP was effective in diminishing this effect. Moreover, PRP increased the levels of enzymatic antioxidants superoxide dismutase and catalase activities in the injured muscle, and also the non-protein thiols (-SH) group levels in erythrocytes. In conclusion PRP, in the form that was used in this study, was able to modulate the oxidative damage determined by a classical skeletal muscle injury possibly by reducing the impairment of myocytes mitochondrial function and improving their endogenous antioxidant defense systems.

Cytokine, chemokine, and growth factor profile of platelet-rich plasma

During wound healing, biologically active molecules are released from platelets. The rationale of using platelet-rich plasma (PRP) relies on the concentration of bioactive molecules and subsequent delivery to healing sites. These bioactive molecules have been seldom simultaneously quantified within the same PRP preparation. In the present study, the flexible Bio-Plex system was employed to assess the concentration of a large range of cytokines, chemokines, and growth factors in 16 healthy volunteers so as to determine whether significant baseline differences may be found. Besides IL-1b, IL-1ra, IL-4, IL-6, IL-8, IL-12, IL-13, IL-17, INF-γ, TNF-α, MCP-1, MIP-1a, RANTES, bFGF, PDGF, and VEGF that were already quantified elsewhere, the authors reported also on the presence of IL-2, IL-5, IL-7, IL-9, IL-10, IL-15 G-CSF, GM-CSF, Eotaxin, CXCL10 chemokine (IP-10), and MIP 1b. Among the most interesting results, it is convenient to mention the high concentrations of the HIV-suppressive and inflammatory cytokine RANTES and a statistically significant difference between males and females in the content of PDGF-BB. These data are consistent with previous reports pointing out that gender, diet, and test system affect the results of platelet function in healthy subjects, but seem contradictory when compared to other quantification assays in serum and plasma. The inconsistencies affecting the experimental results found in literature, along with the variability found in the content of bioactive molecules, urge further research, hopefully in form of randomized controlled clinical trials, in order to find definitive evidence of the efficacy of PRP treatment in various pathologic and regenerative conditions.

Expanded Stem Cells, Stromal-Vascular Fraction, and Platelet-Rich Plasma Enriched Fat: Comparing Results of Different Facial Rejuvenation Approaches in a Clinical Trial

BACKGROUND

In a previous study, the authors demonstrated that treatment with expanded adipose-derived stem cells or stromal vascular fraction (SVF)-enriched fat modify the pattern of the dermis in human beings, representing a skin rejuvenation effect. Considering that expanded stem cells require a cell factor, the authors wanted to assess similar results by replacing them with platelet-rich plasma (PRP), which is easier to obtain and for which an empirical regenerative effect has been already described.

OBJECTIVES

To determine if PRP injection could replace the cutaneous regenerative effect of adipose-derived stem cells.

METHODS

This study was performed in 13 patients who were candidates for facelift. The patients underwent sampling of fat by liposuction from the abdomen and submitted to one of three protocols: injection of SVF-enriched fat or expanded adipose-derived stem cells or fat plus PRP in the preauricular areas. Fragments of skin were removed before and 3 months after treatment and analyzed by optical and electron microscopy.

RESULTS

The use of fat plus PRP led to the presence of more pronounced inflammatory infiltrates and a greater vascular reactivity, increasing in vascular permeability and a certain reactivity of the nervous component. The addition of PRP did not improve the regenerative effect.

CONCLUSION

The use of PRP did not have significant advantages in skin rejuvenation over the use of expanded adipose-derived stem cells or SVF-enriched fat. The effect of increased vascular reactivity may be useful in pathological situations in which an intense angiogenesis is desirable, such as tissular ischemia.

DEPA classification: a proposal for standardising PRP use and a retrospective application of available devices

Background/aim

Significant biological differences in platelet-rich plasma (PRP) preparations have been highlighted and could explain the large variability in the clinical benefit of PRP reported in the literature. The scientific community now recommends the use of classification for PRP injection; however, these classifications are focused on platelet and leucocyte concentrations. This presents the disadvantages of (1) not taking into account the final volume of the preparation; (2) omitting the presence of red blood cells in PRP and (3) not assessing the efficiency of production.

Methods

On the basis of standards classically used in the Cell Therapy field, we propose the DEPA (Dose of injected platelets, Efficiency of production, Purity of the PRP, Activation of the PRP) classification to extend the characterisation of the injected PRP preparation. We retrospectively applied this classification on 20 PRP preparations for which biological characteristics were available in the literature.

Results

Dose of injected platelets varies from 0.21 to 5.43 billion, corresponding to a 25-fold increase. Only a Magellan device was able to obtain an A score for this parameter. Assessments of the efficiency of production reveal that no device is able to recover more than 90% of platelets from the blood. Purity of the preparation reveals that a majority of the preparations are contaminated by red blood cells as only three devices reach an A score for this parameter, corresponding to a percentage of platelets compared with red blood cells and leucocytes over 90%.

Conclusions

These findings should provide significant help to clinicians in selecting a system that meets their specific needs for a given indication.

Hyaluronic acid and tendon lesions

INTRODUCTION

recently, the viscoelastic properties of hyaluronic acid (HA) on liquid connective tissue have been proposed for the treatment of tendinopathies. Some fundamental studies show encouraging results on hyaluronic acid's ability to promote tendon gliding and reduce adhesion as well as to improve tendon architectural organisation. Some observations also support its use in a clinical setting to improve pain and function. This literature review analyses studies relating to the use of hyaluronic acid in the treatment of tendinopathies.

METHODS

this review was constructed using the Medline database via Pubmed, Scopus and Google Scholar. The key words hyaluronic acid, tendon and tendinopathy were used for the research.

RESULTS

in total, 28 articles (in English and French) on the application of hyaluronic acid to tendons were selected for their relevance and scientific quality, including 13 for the in vitro part, 7 for the in vivo animal part and 8 for the human section.

CONCLUSIONS

preclinical studies demonstrate encouraging results: HA permits tendon gliding, reduces adhesions, creates better tendon architectural organisation and limits inflammation. These laboratory observations appear to be supported by limited but encouraging short-term clinical results on pain and function. However, controlled randomised studies are still needed.

Platelet growth factors from allogeneic platelet-rich plasma for clinical improvement in split-thickness skin graft

Background and objectives:

Platelets are a source of numerous growth factors which facilitate repair and healing. Thus platelet rich plasma has been increasingly used as a treatment modality in the field of reconstructive surgeries for wound healing. This preliminary study was carried out to explore whether platelet growth factors from platelet rich plasma could be used for enhancement of split thickness skin graft survival.

Materials and Methods:

Twenty patients (13 males and 7 females) requiring split thickness skin graft for various clinical reasons were enrolled in the study. Platelet rich plasma was collected by apheresis and frozen at −80° C. It was thawed at room temperature immediately before its intended application. PRP was applied only on one half of the wound, while another half served as control. Patient was followed for 6 weeks. The effect was assessed at first dressing in terms of graft uptake and subsequently as time taken for complete healing.

Results:

There was 100% uptake of the graft in the area where platelet rich plasma was applied. In the control area, there was complete graft loss in 4 cases, partial loss in 7 cases and complete uptake in 9 cases.

Conclusion:

This study demonstrated promising results on application of PRP to split thickness skin grafts. Further randomized studies with greater sample size may be undertaken to establish platelet rich plasma as a validated treatment modality.

The growing evidence for the use of platelet-rich plasma on diabetic chronic wounds: A review and a proposal for a new standard care

Nonhealing chronic wounds and exposed tendons, bones and joints are very challenging to cure specially for diabetic patients. Plastic surgeons have a new weapon to enhance wound healing with the use of autologous growth factors. Recently, the process of fabrication of platelet-rich plasma (PRP) has been simplified. The goal of this literature review is to summarize the evidenced-based body of knowledge regarding the treatment of diabetic chronic wounds by PRP. A PubMed and Cochrane search (1978-2015) was performed and all studies assessing the clinical effect of PRP on the healing of diabetic chronic wounds were included. The screening retrieved 7,555 articles and 12 studies were included. On six randomized studies included, five found significant benefits for the use of PRP on diabetic chronic foot ulcers and the sixth randomized study did not publish a statistical analysis but found favorable outcomes. The two other controlled studies included found significant benefits regarding the healing rate and the four uncontrolled studies included showed high rates of healing with the adjunction of PRP. Regarding the method of use, PRP was applied on the wound as a gel twice a week (41.7% of studies) or once a week (33.3% of studies). In conclusion, 87.5% of controlled studies found a significant benefit for the adjunction of PRP to treat chronic diabetic wounds. As PRP may be beneficial, we suggest using PRP on diabetic ulcers which remain unhealed after standard treatment.

Tendinopathies and platelet-rich plasma (PRP): from pre-clinical experiments to therapeutic use

OBJECTIVES

The restorative properties of platelets, through the local release of growth factors, are used in various medical areas. This article reviews fundamental and clinical research relating to platelet-rich plasma applied to tendinous lesions.

MATERIALS AND METHOD

Articles in French and English, published between 1 January 2012 and 31 December 2014. dealing with PRP and tendons were searched for using the Medline and Scopus data bases.

RESULTS

Forty-seven articles were identified which addressed pre-clinical and clinical studies: 27 relating to in vitro and in vivo animal studies and 20 relating to human studies. Of these, five addressed lateral epicondylitis, two addressed rotator cuff tendinopathies, ten dealt with patellar tendinopathies and three looked at Achilles tendinopathies.

CONCLUSIONS

The majority of pre-clinical studies show that PRP stimulates the tendon's healing process. However, clinical series remain more controversial and level 1, controlled, randomised studies are still needed.

New and emerging strategies in platelet-rich plasma application in musculoskeletal regenerative procedures: general overview on still open questions and outlook

Despite its pervasive use, the clinical efficacy of platelet-rich plasma (PRP) therapy and the different mechanisms of action have yet to be established. This overview of the literature is focused on the role of PRP in bone, tendon, cartilage, and ligament tissue regeneration considering basic science literature deriving from in vitro and in vivo studies. Although this work provides evidence that numerous preclinical studies published within the last 10 years showed promising results concerning the application of PRP, many key questions remain unanswered and controversial results have arisen. Additional preclinical studies are needed to define the dosing, timing, and frequency of PRP injections, different techniques for delivery and location of delivery, optimal physiologic conditions for injections, and the concomitant use of recombinant proteins, cytokines, additional growth factors, biological scaffolds, and stems cells to develop optimal treatment protocols that can effectively treat various musculoskeletal conditions.

Platelet-rich plasma in orthopedic therapy: a comparative systematic review of clinical and experimental data in equine and human musculoskeletal lesions

BACKGROUND

This systematic review aimed to present and critically appraise the available information on the efficacy of platelet rich plasma (PRP) in equine and human orthopedic therapeutics and to verify the influence of study design and methodology on the assumption of PRP's efficacy. We searched Medline, PubMed, Embase, Bireme and Google Scholar without restrictions until July 2013. Randomized trials, human cohort clinical studies or case series with a control group on the use of PRP in tendons, ligaments or articular lesions were included. Equine clinical studies on the same topics were included independently of their design. Experimental studies relevant to the clarification of PRP's effects and mechanisms of action in tissues of interest, conducted in any animal species, were selected.

RESULTS

This review included 123 studies. PRP's beneficial effects were observed in 46.7% of the clinical studies, while the absence of positive effects was observed in 43.3%. Among experimental studies, 73% yielded positive results, and 7.9% yielded negative results. The most frequent flaws in the clinical trials' designs were the lack of a true placebo group, poor product characterization, insufficient blinding, small sampling, short follow-up periods, and adoption of poor outcome measures. The methods employed for PRP preparation and administration and the selected outcome measures varied greatly. Poor study design was a common feature of equine clinical trials. From studies in which PRP had beneficial effects, 67.8% had an overall high risk of bias. From the studies in which PRP failed to exhibit beneficial effects, 67.8% had an overall low risk of bias.

CONCLUSIONS

Most experimental studies revealed positive effects of PRP. Although the majority of equine clinical studies yielded positive results, the human clinical trials' results failed to corroborate these findings. In both species, beneficial results were more frequently observed in studies with a high risk of bias. The use of PRP in musculoskeletal lesions, although safe and promising, has still not shown strong evidence in clinical scenarios.

Tendon injury: from biology to tendon repair

Tendon is a crucial component of the musculoskeletal system. Tendons connect muscle to bone and transmit forces to produce motion. Chronic and acute tendon injuries are very common and result in considerable pain and disability. The management of tendon injuries remains a challenge for clinicians. Effective treatments for tendon injuries are lacking because the understanding of tendon biology lags behind that of the other components of the musculoskeletal system. Animal and cellular models have been developed to study tendon-cell differentiation and tendon repair following injury. These studies have highlighted specific growth factors and transcription factors involved in tenogenesis during developmental and repair processes. Mechanical factors also seem to be essential for tendon development, homeostasis and repair. Mechanical signals are transduced via molecular signalling pathways that trigger adaptive responses in the tendon. Understanding the links between the mechanical and biological parameters involved in tendon development, homeostasis and repair is prerequisite for the identification of effective treatments for chronic and acute tendon injuries.

Effectiveness of xenogenous-based bovine-derived platelet gel embedded within a three-dimensional collagen implant on the healing and regeneration of the Achilles tendon defect in rabbits

BACKGROUND AND OBJECTIVE

Tissue engineering is an option in reconstructing large tendon defects and managing their healing and regeneration. We designed and produced a novel xenogeneic-based bovine platelet, embedded it within a tissue-engineered collagen implant (CI) and applied it in an experimentally induced large tendon defect model in rabbits to test whether bovine platelets could stimulate tendon healing and regeneration in vivo.

METHODS

One hundred twenty rabbits were randomly divided into two experimental and pilot groups. In all the animals, the left Achilles tendon was surgically excised and the tendon edges were aligned by Kessler suture. Each group was then divided into three groups of control (no implant), treated with CI and treated with collagen-platelet implant. The pilot groups were euthanized at 10, 15, 30 and 40 days post-injury (DPI), and their gross and histologic characteristics were evaluated to study host-graft interaction mechanism. To study the tendon healing and its outcome, the experimental animals were tested during the experiment using hematologic, ultrasonographic and various methods of clinical examinations and then euthanized at 60 DPI and their tendons were evaluated by gross pathologic, histopathologic, scanning electron microscopic, biophysical and biochemical methods.

RESULTS

Bovine platelets embedded within a CI increased inflammation at short term while it increased the rate of implant absorption and matrix replacement compared with the controls and CI alone. Treatment also significantly increased diameter, density, amount, alignment and differentiation of the collagen fibrils and fibers and approximated the water uptake and delivery behavior of the healing tendons to normal contralaterals (p < 0.05). Treatment also improved echogenicity and homogenicity of the tendons and reduced peritendinous adhesion, muscle fibrosis and atrophy, and therefore, it improved the clinical scores and physical activity related to the injured limb when compared with the controls (p < 0.05).

CONCLUSION

The bovine platelet gel embedded within the tissue-engineered CI was effective in healing, modeling and remodeling of the Achilles tendon in rabbit. This strategy may be a valuable option in the clinical setting.

Exuberant inflammatory reaction as a side effect of platelet-rich plasma injection in treating one case of tendinopathy

Platelet-rich plasma (PRP) contains a large number of growth factors, which may enhance tendon healing processes. Local injection of PRP represents a relatively new treatment for tendinopathies. To date, no side effects have been reported after injection of PRP to treat tendinopathy. We report a case of exuberant inflammatory reaction after 1 injection of PRP to treat jumper's knee in a 35-year-old male type 1 diabetic patient. Injections of PRP should be proposed only after careful consideration in cases of patients with morbidity risks linked to insulin-dependent diabetes.

Characteristics of platelet gels combined with silk

Platelet gel, a fibrin network containing activated platelets, is widely used in regenerative medicine due the capacity of platelet-derived growth factors to accelerate and direct healing processes. However, limitations to this approach include poor mechanical properties, relatively rapid degradation, and the lack of control of release of growth factors at the site of injection. These issues compromise the ability of platelet gels for sustained function in regenerative medicine. In the present study, a combination of platelet gels with silk fibroin gel was studied to address the above limitations. Mixing sonicated silk gels with platelet gels extended the release of growth factors without inhibiting gel-forming ability. The released growth factors were biologically active and their delivery was modified further by manipulation of the charge of the silk protein. Moreover, the silk gel augmented both the rheological properties and compressive stiffness of the platelet gel, tuned by the silk concentration and/or silk/platelet gel ratio. Silk-platelet gel injections in nude rats supported enhanced cell infiltration and blood vessel formation representing a step towards new platelet gel formulations with enhanced therapeutic impact.

Platelet-rich plasma preparation for regenerative medicine: optimization and quantification of cytokines and growth factors

Introduction

Platelet-rich plasma (PRP) is nowadays widely applied in different clinical scenarios, such as orthopedics, ophthalmology and healing therapies, as a growth factor pool for improving tissue regeneration. Studies into its clinical efficiency are not conclusive and one of the main reasons for this is that different PRP preparations are used, eliciting different responses that cannot be compared. Platelet quantification and the growth factor content definition must be defined in order to understand molecular mechanisms behind PRP regenerative strength. Standardization of PRP preparations is thus urgently needed.

Methods

PRP was prepared by centrifugation varying the relative centrifugal force, temperature, and time. Having quantified platelet recovery and yield, the two-step procedure that rendered the highest output was chosen and further analyzed. Cytokine content was determined in different fractions obtained throughout the whole centrifugation procedure.

Results

Our method showed reproducibility when applied to different blood donors. We recovered 46.9 to 69.5% of total initial platelets and the procedure resulted in a 5.4-fold to 7.3-fold increase in platelet concentration (1.4 × 10⁶ to 1.9 × 10⁶ platelets/μl). Platelets were highly purified, because only <0.3% from the initial red blood cells and leukocytes was present in the final PRP preparation. We also quantified growth factors, cytokines and chemokines secreted by the concentrated platelets after activation with calcium and calcium/thrombin. High concentrations of platelet-derived growth factor, endothelial growth factor and transforming growth factor (TGF) were secreted, together with the anti-inflammatory and proinflammatory cytokines interleukin (IL)-4, IL-8, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-α. No cytokines were secreted before platelet activation. TGF-β3 and IFNγ were not detected in any studied fraction. Clots obtained after platelet coagulation retained a high concentration of several growth factors, including platelet-derived growth factor and TGF.

Conclusions

Our study resulted in a consistent PRP preparation method that yielded a cytokine and growth factor pool from different donors with high reproducibility. These findings support the use of PRP in therapies aiming for tissue regeneration, and its content characterization will allow us to understand and improve the clinical outcomes.

Effects of platelet-rich plasma (PRP) on the healing of Achilles tendons of rats

Platelet-rich plasma (PRP) contains growth factors involved in the tissular healing process. The aim of the study was to determine if an injection of PRP could improve the healing of sectioned Achilles tendons of rats. After surgery, rats received an injection of PRP (n = 60) or a physiological solution (n = 60) in situ. After 5, 15, and 30 days, 20 rats of both groups were euthanized and 15 collected tendons were submitted to a biomechanical test using cryo-jaws before performing transcriptomic analyses. Histological and biochemical analyses were performed on the five remaining tendons in each group. Tendons in the PRP group were more resistant to rupture at 15 and 30 days. The mechanical stress was significantly increased in tendons of the PRP group at day 30. Histological analysis showed a precocious deposition of fibrillar collagen at day 5 confirmed by a biochemical measurement. The expression of tenomodulin was significantly higher at day 5. The messenger RNA levels of type III collagen, matrix metalloproteinases 2, 3, and 9, were similar in the two groups at all time points, whereas type I collagen was significantly increased at day 30 in the PRP group. In conclusion, an injection of PRP in sectioned rat Achilles tendon influences the early phase of tendon healing and results in an ultimately stronger mechanical resistance.