Optimizing platelet-rich plasma gel formation by varying time and gravitational forces during centrifugation

Current Challenges in the Development of Platelet-Rich Plasma-Based Therapies

Nowadays, biological therapies are booming and more of these formulations are coming to the market. Platelet-rich plasma, or PRP, is one of the most widely used biological therapies due to its ease of obtention and autologous character. Most of the techniques to obtain PRP are focusing on new processes and methods of optimization. However, not enough consideration is being given to modify the molecular components of PRP to generate more effective formulations with the aim of improving PRP treatments. Therefore, this review covers different novel PRP-obtaining methods that attempt to modify the molecular composition of the plasma.

A model approach to show that monocytes can enter microporous β-TCP ceramics

β-TCP ceramics are versatile bone substitute materials and show many interactions with cells of the monocyte-macrophage-lineage. The possibility of monocytes entering microporous β-TCP ceramics has however not yet been researched. In this study, we used a model approach to investigate whether monocytes might enter β-TCP, providing a possible explanation for the origin of CD68-positive osteoclast-like giant cells found in earlier works.We used flow chambers to unidirectionally load BC, PRP, or PPP into slice models of either 2 mm or 6 mm β-TCP. Immunofluorescence for CD68 and live/dead staining was performed after the loading process.Our results show that monocytes were present in a relevant number of PRP and BC slices representing the inside of our 2 mm slice model and also present on the actual inside of our 6 mm model. For PPP, monocytes were not found beyond the surface in either model.Our results indicate the possibility of a new and so far neglected constituent in β-TCP degradation, perhaps causing the process of ceramic degradation also starting from inside the ceramics as opposed to the current understanding. We also demonstrated flow chambers as a possible new in vitro model for interactions between blood and β-TCP.

Ultrafast gelling bioadhesive based on blood plasma and gelatin for wound closure and healing

Tissue adhesives offer a plethora of advantages in achieving efficient wound closure over conventional sutures and staples. Such materials are of great value, especially in cases where suturing could potentially damage tissues or compromise blood flow or in cases of hard-to-reach areas. Besides providing wound closure, the tissue adhesives must also facilitate wound healing. Previously, plasma-based tissue adhesives and similar bioinspired strategies have been utilized to aid in wound healing. Still, their application is constrained by factors such as high cost, diminished biocompatibility, prolonged gelation times, inadequate swelling, quick resorption, as well as short-term and inconsistent efficacy. To address these limitations, we report the development of a highly biocompatible and ultrafast-gelling tissue adhesive hydrogels. Freeze-dried platelet-rich plasma, heat-denatured freeze-dried platelet-poor plasma, and gelatin were utilized as the base matrix. Gelation was initiated by adding tetrakis hydroxymethyl phosphonium chloride. The fabricated gels displayed rapid gelation (3-4 s), low swelling, increased proliferation, and migration against L929 cells and had porcine skin tissue adhesion strength similar to that of plasma-based commercial glue (Tisseel®).

Platelet-Rich Plasma (PRP) for Endometrial Treatment Efficacy and Safety in Assisted Reproductive Technology: A Comprehensive Review

Platelet-rich plasma (PRP) is among the new ground-breaking methods called for endometrial disorders detected in assisted reproductive technology (ART). This research work takes account of both a systematic literature review and an exploration of the molecular connections. The report aims to present the capabilities and benefits of the PRP in ART and the nonconformance and dangers involved in its use in ART. However, all these stages of ART need conducive endometrium, live micro embryo, and coordinated interaction between the blastocyst and the uterus. Despite all ART has achieved, implantation failure still exists as a problem having one quarter being attributed to the absence of the endometrial receptivity level. The review points to a corresponding increase in the role of autologous PRP in promoting cell proliferation, neo-angiogenesis, and anti-inflammatory effects to facilitate effective endometrial receptivity. The outcome of prior trials with the PRP approach proved to be positive for women with adenomyosis, thin endometrial lining, recurring implantation failure, chronic endometritis, and Asherman's syndrome. Challenges still exist in the proper placement of PRP for all women with infertility problems as well as how it works for individuals with blood disorders and infections. This study will look into the safest number of doses, the time of acting, and the possible future health hazards that both mother and child may face.

Effect of platelet-rich plasma in Achilles tendon allograft in rabbits

BACKGROUND

Achilles tendon is composed of dense connective tissue and is one of the largest tendons in the body. In veterinary medicine, acute ruptures are associated with impact injury or sharp trauma. Healing of the ruptured tendon is challenging because of poor blood and nerve supply as well as the residual cell population. Platelet-rich plasma (PRP) contains numerous bioactive agents and growth factors and has been utilized to promote healing in bone, soft tissue, and tendons.

OBJECTIVE

The purpose of this study was to evaluate the healing effect of PRP injected into the surrounding fascia of the Achilles tendon after allograft in rabbits.

METHODS

Donor rabbits (n = 8) were anesthetized and 16 lateral gastrocnemius tendons were fully transected bilaterally. Transected tendons were decellularized and stored at -80°C prior to allograft. The allograft was placed on the partially transected medial gastrocnemius tendon in the left hindlimb of 16 rabbits. The allograft PRP group (n = 8) had 0.3 mL of PRP administered in the tendon and the allograft control group (n = 8) did not receive any treatment. After 8 weeks, rabbits were euthanatized and allograft tendons were transected for macroscopic, biomechanical, and histological assessment.

RESULTS

The allograft PRP group exhibited superior macroscopic assessment scores, greater tensile strength, and a histologically enhanced healing process compared to those in the allograft control group.

CONCLUSIONS

Our results suggest administration of PRP on an allograft tendon has a positive effect on the healing process in a ruptured Achilles tendon.

Optimization of Platelet-Rich Plasma Preparation for Regenerative Medicine: Comparison of Different Anticoagulants and Resuspension Media

Platelet-rich plasma (PRP) has emerged as a promising therapy in regenerative medicine. However, the lack of standardization in PRP preparation protocols presents a challenge in achieving reproducible and accurate results. This study aimed to optimize the PRP preparation protocol by investigating the impact of two different anticoagulants, sodium citrate (SC) and ethylenediaminetetraacetic acid (EDTA), and resuspension media, plasma versus sodium chloride (NaCl). Platelet recovery rates were calculated and compared between groups, in addition to platelet activity and vascular endothelial growth factor (VEGF) released into plasma after PRP activation. The platelet recovery rate was higher with EDTA in comparison to SC (51.04% vs. 29.85%, p = 0.005). Platelet activity was also higher, with a higher expression of two platelet antibodies, platelet surface P-Selectin (CD62p) and PAC-1, in the EDTA group. The concentration of VEGF was higher with SC in comparison to EDTA (628.73 vs. 265.44 pg/mL, p = 0.013). Platelet recovery rates and VEGF levels were higher in PRP resuspended in plasma when compared to NaCl (61.60% vs. 48.61%, p = 0.011 and 363.32 vs. 159.83 pg/mL, p = 0.005, respectively). Our study reinforces the superiority of EDTA (as anticoagulant) and plasma (for resuspension) in obtaining a higher platelet recovery and preserving platelet functionality during PRP preparation.

Optimizing Platelet-Rich Plasma: Spin Time and Sample Source

The buff-colored layer separating the plasma from red blood cells (RBCs) in centrifuged blood was named the "buffy coat" in the late 19th century. The division of platelets (PLTs) and leukocytes (WBCs) between the buffy coat, plasma, and RBC layers in centrifuged blood has not been described before. In this study, we centrifuged 8.5 mL anticoagulated blood samples at 1000× g for 1, 2, 3, 5, 10, and 20 min. We then divided each sample into ten layers and analyzed each layer for cellular composition and mean platelet volume (MPV). Our results show that even after 20 min of centrifugation, about 15% of platelets remain in the plasma layers and 65% in the RBC layers. We found that the platelet count achieved from aspiration of 1 mL volume was optimal, with aspiration beginning 1/2 mL below the buffy coat and extending 1/2 mL above the buffy coat rather than beginning at the buffy coat itself and aspirating only plasma. Using this method of aspiration, we found that the total platelet count means reached a maximum in the 1 mL around the buffy coat after only 5 min of centrifugation.

Intraovarian Platelet-Rich Plasma Injections: Safety and Thoughts on Efficacy Based on a Single Centre Experience With 469 Women

BACKGROUND

Ovarian rejuvenation is an innovative procedure intended to restore ovarian fertility and development during the climacteric and has been used to enhance fertility in women with premature ovarian insufficiency (POI). This retrospective study was conducted to determine the effects of an intraovarian platelet-rich plasma (PRP) injection on ovarian stimulation outcomes in women referred to an in vitro fertilisation centre. Methods-Population: This was a retrospective observational study, and the inclusion criteria included women of reproductive age with at least one ovary with a history of infertility, hormonal abnormalities, an absence of a menstrual cycle, and premature ovarian failure. During the patient's first consultation, a detailed reproductive history was recorded, a pelvic scan for ovarian size was conducted, and hormonal analysis for follicle-stimulating hormone (FSH), anti-Müllerian hormone (AMH), estradiol (E2), and luteinizing hormone (LH) was conducted.

RESULTS

In the study, 469 women with a history of infertility, hormonal abnormalities, an absence of a menstrual cycle, and premature ovarian failure had hormonal levels recorded up to four months after treatment, and these were included in the study. The volume of peripheral blood required to prepare 6-8 mL of PRP for administration was 40-60 mL. The initial concentration of platelets in the peripheral blood sample was about 25000/µL, whereas the prepared PRP had a concentration of 900.000/µL. A volume of approximately 2-4 mL per ovary, depending on the ovarian volume, was used for the intraovarian injection. PRP intervention had significant effects on FSH concentration at the α = 0.05 level. Statistically significant increases in normal values of FSH and E2were observed for months three and four after the PRP intervention for all age groups.

CONCLUSIONS

The results of our observational study revealed that a PRP intraovarian injection is associated with improved ovarian tissue and function. Future randomised clinical trials are needed to shed light on the use of PRP in ovarian rejuvenation before offering it routinely in clinical practice.

Interest of platelet rich plasma in Achilles tendon rupture management: a systematic review

OBJECTIVES

Acute Achilles tendon rupture (ATR) is a disabling sport-related injury. Its management involves conservative treatment with early weight-bearing or surgical treatment. Platelet-rich plasma (PRP) has raised interest as an adjuvant for treatment, given its properties on tendon repair and its anti-inflammatory effect. We aimed to assess clinical impact of PRP use in surgical or non-surgical treatment of acute ATR: range of motion, muscle strength, function, return to sport and adverse events.

METHOD

A systematic literature research was performed using PubMed, ScienceDirect, and Google Scholar databases to collect studies reporting clinical outcomes after acute ATR treated with PRP.

RESULTS

Eight studies were eligible and included 543 acute ATR. Four were randomized comparative studies. A total of 128 patients were treated surgically and 415 were treated conservatively, 271 received PRP injection. Five studies described the type of PRP used, which was variable. Only one study including 12 patients found significant outcomes in favor of the PRP group, with a 4-week earlier recovery of a normal range of motion and a 7-week earlier return to running. No difference in clinical or morphological evaluations, strength measurement, and functional outcomes was found in other studies both at short and long-term. PRP did not seem to modify the frequency of adverse events.

CONCLUSIONS

Data are not clearly in favor of a significant effect of the PRP use for treatment of ATR. There might be a slight effect on evolution during the first months. Its interest should be assessed in future studies with strong methodology.

Modifying Orthobiological PRP Therapies Are Imperative for the Advancement of Treatment Outcomes in Musculoskeletal Pathologies

Autologous biological cellular preparations have materialized as a growing area of medical advancement in interventional (orthopedic) practices and surgical interventions to provide an optimal tissue healing environment, particularly in tissues where standard healing is disrupted and repair and ultimately restoration of function is at risk. These cellular therapies are often referred to as orthobiologics and are derived from patient's own tissues to prepare point of care platelet-rich plasma (PRP), bone marrow concentrate (BMC), and adipose tissue concentrate (ATC). Orthobiological preparations are biological materials comprised of a wide variety of cell populations, cytokines, growth factors, molecules, and signaling cells. They can modulate and influence many other resident cells after they have been administered in specific diseased microenvironments. Jointly, the various orthobiological cell preparations are proficient to counteract persistent inflammation, respond to catabolic reactions, and reinstate tissue homeostasis. Ultimately, precisely delivered orthobiologics with a proper dose and bioformulation will contribute to tissue repair. Progress has been made in understanding orthobiological technologies where the safety and relatively easy manipulation of orthobiological treatment tools has been demonstrated in clinical applications. Although more positive than negative patient outcome results have been registered in the literature, definitive and accepted standards to prepare specific cellular orthobiologics are still lacking. To promote significant and consistent clinical outcomes, we will present a review of methods for implementing dosing strategies, using bioformulations tailored to the pathoanatomic process of the tissue, and adopting variable preparation and injection volume policies. By optimizing the dose and specificity of orthobiologics, local cellular synergistic behavior will increase, potentially leading to better pain killing effects, effective immunomodulation, control of inflammation, and (neo) angiogenesis, ultimately contributing to functionally restored body movement patterns.

Regenerative Medicine Treatments for Androgenetic Alopecia

Regenerative medicine and the role of stem cells are being studied for applications in nearly every field of medicine. The pluripotent nature of stem cells underlies their vast potential for treatment of androgenic alopecia. Several advances in recent years have heightened interest in this field, chief among them are the evolution of simpler techniques to isolate regenerative elements and stems cells. These techniques are easy, outpatient procedures with immediate injection, often single session with harvest, and minimal manipulation (usually physical). This paper seeks to critically review the existing data and determine the current evidence and their role in practice.

Reducing split-thickness skin grafting donor site agony; faster healing and decreased pain-role of platelet-rich plasma

INTRODUCTION

The split-thickness skin graft harvested donor site is associated with prolonged healing, discomfort, and pain. Platelet-rich plasma (PRP) contains platelet-derived growth factors and has been widely used in chronic wounds and skin graft donor sites. PRP application is known to accelerate wound epithelialization rates, and also reduce postoperative wound site pain.

MATERIALS AND METHODS

We assessed 20 patients admitted to our hospital service who underwent split-thickness skin grafting (STSGs) with proximal half of the donor site treated with PRP. The dressing was conducted on postoperative day 7, 14, and 21. The donor site healing was assessed with serial photographs and donor site pain measured by numerical rating scale.

RESULTS

Complete healing of wounds (epithelialization) was present in 12 (60%) patients dressed with PRP. Pain on opening dressing was an average of 3.5 in PRP dressed wounds and 6.35 in control wounds. Patients dressed without PRP, none of them had complete epithelialization. All patients had partial healing and were less than the donor site dressed with PRP. Based on these results, skin graft donor site with PRP showed accelerated healing and reduced pain and discomfort compared to control without PRP.

CONCLUSION

PRP is a beneficial adjunct for reducing donor site pain and increased healing of donor site following STSG harvest.

Platelet-rich plasma in hair loss-Mechanism, preparation, and classification

Platelet-rich plasma is the autologous plasma containing platelet concentration more than the baseline separated after centrifugation. It has become a very popular option for the treatment of hair loss in the past few decades. Used alone or in combination with other treatment options it has found a place as a hair restoration procedure throughout the world. However, evidence supporting its credibility is quite ambiguous with contradictory reports available in the literature. In this article, we try to analyze the available data regarding its mechanism of action, preparation protocols, and classification, with regard to hair loss.

Evaluation of the Effects of Platelet-Rich Plasma on Follicular and Endometrial Growth: A Literature Review

Platelet-rich plasma (PRP) has been used in several areas of medicine due to its ability to promote tissue regeneration by growth factors and cytokines. This review addresses the use of PRP to rejuvenate ovarian follicles and increase the thickness of the endometrium to receive an embryo. PRP is obtained from the patient's own blood (autologous blood) - a fact that determines a lower chance of rejection reactions. Alpha granules of platelets provide and release supra physiological amounts of growth factors and cytokines, which provide a regenerative stimulus in tissues with low healing potential. In the ovary, PRP and its growth factors stimulate vascularization and recruitment of available primordial follicles that could no longer be otherwise stimulated. The rejuvenation of the ovary by PRP infusion aims to obtain new oocytes in ovaries with low numbers of follicles or low follicular reserve markers. In the preparation of the endometrium, PRP is used for its several growth factors that allow tissue proliferation and endometrial thickening, especially in cases of endometria that are difficult to prepare or that fail to reach an adequate minimum thickness (>7mm). To date, there are few studies of greater expression in the literature that support the use of PRP with the two purposes described above. Thus, although promising, the technique must still be validated by larger clinical trials.

The Role of Autologous PRP on Deep Partial-Thickness Burn Wound Healing in Bama Pigs

In this study, we aimed to evaluate the therapeutic effects of autologous platelet-rich plasma (PRP) on deep partial-thickness burns in Bama pigs. Deep partial-thickness burn wounds were created on the back of Bama pigs. The reepithelialization time was compared between the PRP and control groups. The mean score of Ki67 (+) cells and α-SMA (+) vessels, the mean thickness of epidermis and dermis of the healing wounds were determined via H&E staining and immunohistochemical assay. The levels of the growth factors epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) were examined by ELISA. Our data showed that the time to wound reepithelialization was shorter in the PRP group compared with the control group. The thickness of the epidermis was larger in the PRP group compared with the control group. On the 7th and 14th days after the treatment, the mean score of Ki67 (+) cells and α-SMA (+) vessels were higher in the PRP group compared with the control group. The PRP group showed higher levels of growth factors (EGF, bFGF, and VEGF) compared with the control group by ELISA. The results indicated that PRP could improve wound healing process of deep partial-thickness burns in Bama pigs. The PRP increased the thickness of epidermis of the healed wounds, cell proliferation, and angiogenesis. We demonstrated that applying PRP had a greater potential for the treatment of deep partial-thickness burns.

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].

A cross-sectional analysis of the effects of various centrifugation speeds and inclusion of the buffy coat in platelet-rich plasma preparation

INTRODUCTION

Platelet-rich plasma is an autologous blood preparation which is used in various medical specialties because of its regenerative properties. There is a wide variation in platelet-rich plasma preparation protocols and attaining the ideal platelet yield (>1 million platelets/μL) in a clinic setting can be challenging. We aimed at analyzing the centrifuge spin rates at which to attain an ideal platelet-rich plasma yield and also to study the effect of inclusion of the buffy coat after the first spin on the final platelet concentration in platelet-rich plasma.

METHODS

Seventy-five whole blood samples were obtained and divided into two groups - (1) leukocyte-rich platelet-rich plasma group and (2) leukocyte-poor platelet-rich plasma group. Samples in both groups were centrifuged using the dual spin method, at one of three centrifugation speed combinations (initial "soft" spin and second "hard" spin speeds, respectively): (1) 100 g/400 g, (2) 350 g/1350 g and (3) 900 g/1800 g. Platelet, red blood cell (RBC) and white blood cell (WBC) counts in both groups were compared.

RESULTS

The 100 g/400 g spin gave a high platelet yield (increase of 395.4 ± 111.1%) in the leukocyte-poor-platelet-rich plasma group, while in the leukocyte-rich platelet-rich plasma group both 100 g/400 g and 350 g/1350 g spins resulted in significantly higher yields with an increase of 691.5 ± 316.3% and 738.6 ± 193.3%, respectively.

LIMITATIONS

The study was limited by a smaller sample size in the pure platelet-rich plasma (leukocyte-poor platelet-rich plasma) group.

CONCLUSION

Ideal platelet yields can be achieved with both the 100 g/400 g as well as the 350 g/1350 g spins using the buffy coat inclusion method while the 100 g/400 g spin for "pure" platelet-rich plasma accomplishes a near-ideal platelet count with significantly reduced contamination with other cells.

Efficacy of Intraoperative Platelet-Rich Plasma Augmentation and Postoperative Platelet-Rich Plasma Booster Injection for Rotator Cuff Healing: A Randomized Controlled Clinical Trial

Background:

Platelet-rich plasma (PRP) has been applied as an adjuvant treatment for arthroscopic rotator cuff repair (ARCR) to enhance rotator cuff healing. However, it remains debatable whether PRP enhances tendon-to-bone healing.

Purpose:

To assess the efficacy of intraoperative augmentation and postoperative injection of PRP that was prepared using the double-spin method and calcium activation without thrombin in patients with ARCR.

Study Design:

Randomized controlled trial; Level of evidence, 1; and cohort study; Level of evidence, 3.

Methods:

A total of 58 patients underwent ARCR using intraoperative PRP augmentation. Half of the patients were randomly assigned to receive an additional ultrasound-guided PRP injection at the repair site at 2 weeks postoperatively (PRP-booster group); the other half did not receive the booster injection (PRP-only group). A control group that did not receive any PRP treatment was retrospectively matched using propensity score matching. Structural integrity was assessed using magnetic resonance imaging at 1 year postoperatively, and healing rates were compared between patients with tear sizes ≤2 cm versus >2 cm. Functional outcomes were assessed using the visual analog scale (VAS) for pain; VAS for satisfaction; shoulder range of motion; and Constant, American Shoulder and Elbow Surgeons, and Simple Shoulder Test scores at minimum 2-year follow-up.

Results:

In patients with tears >2 cm, the rate of healing failure at 1-year follow-up was significantly less in the overall PRP group than in the control group (12.9% vs 35.7%, respectively; P = .040), however, the PRP-booster group did not present a better healing rate than did the PRP-only group. The overall PRP group had lower VAS for pain scores compared with the control group (0.5 ± 1.1 vs 1.3 ± 1.8, respectively; P = .016) and higher VAS for satisfaction scores (9.2 ± 1.2 vs 8.6 ± 1.7; P = .023) at the final follow-up, whereas no statistical difference was found between the PRP-only and PRP-booster groups in functional outcomes.

Conclusion:

Intraoperative PRP augmentation during ARCR demonstrated superior anatomic healing results in patients with rotator cuff tears >2 cm as well as reduced pain and increased subjective satisfaction. PRP booster injection provided no additional benefit to tendon integrity or functional recovery.

Combined use of calcium phosphate cement, mesenchymal stem cells and platelet-rich plasma for bone regeneration in critical-size defect of the femoral condyle in mini-pigs

Aim: To investigate the outcome of autologous bone marrow mesenchymal stem cells (BMMSCs) and platelet-rich plasma in combination with calcium phosphate cement (CPC) scaffold to reconstruct femoral critical bone defects in mini-pigs. Materials & methods: Scanning electron microscopy, micro-computed tomography evaluation and quantitative histological assessment were used. Results & conclusion: BMMSCs were attached to the CPC scaffold after 7 days of culture and decreased the residual CPC material in each group at 12 weeks compared with 6 weeks. The newly formed bone area was higher in the CPC+SC+P group than in the CPC group at each time point (all p < 0.05). The strategy of CPC combined with BMMSCs and platelet-rich plasma might be an effective method to repair bone defects.

An update on platelet-rich plasma (PRP) therapy in endometrium and ovary related infertilities: clinical and molecular aspects

Administration of platelet-rich plasma (PRP) is one of the well-recommended strategies for the treatment of endometrium- and ovary-associated infertility. Due to the autologous source of PRP, minimal risks for disease transmission and immunogenic and allergic responses are expected in this method. Despite the extensive use of PRP in medicine, its precise mechanism of action in endometrial and ovarian tissues is still unknown. Nevertheless, the induction of cell proliferation, chemotaxis, regeneration, extracellular matrix synthesis, remodeling, angiogenesis, and epithelialization are the main pathways for PRP to affect female reproductive organs. Given the promising results of previous studies, it is necessary to standardize PRP preparation protocols for different therapeutic purposes and also clearly determine appropriate inclusion and exclusion criteria for recruiting patients. In the current review, we presented a summary of studies on PRP therapy for endometrium- and ovary-associated infertility with a focus on the possible mechanisms by which PRP enhances endometrial receptivity and regenerates ovarian function.Abbreviations: PRP: platelet-rich plasma; ART: assisted reproductive technology; POF: premature ovarian failure; TGF: transforming growth factors; PDGF: platelet-derived growth factors; IGF-I: insulin-like growth factor-1; HGF: hepatocyte growth factor; EGF: epidermal growth factor; FGF: fibroblast growth factor; VEGF: vascular endothelial growth factor; ADP: adenosine diphosphate, ATP: adenosine triphosphate; PDGF: platelet-derived growth factor; COX2: cyclooxygenase-2; TP53: tumor protein 53; ER-α: estrogen receptors alpha; ER-β: estrogen receptors beta; PR: progesterone receptor; RIF: recurrent implantation failure; G-CSF: granulocyte colony-stimulating factor; iNOS: inducible nitric oxide synthase; NF-kβ: nuclear factor kappa beta; MMPs: matrix metalloproteinases; Col1a1: collagen type I alpha 1; IL: interleukin; FSH: follicle-stimulating hormone; AMH: anti-Mullerian hormone; GDF-9: growth differentiation factor 9.

Preparation of platelet-rich plasma: National IADVL PRP taskforce recommendations

The goal of these recommendations is to provide a framework to practitioners for implementing useful, evidence-based recommendations for the preparation of platelet-rich plasma (PRP) in various dermatological indications. The Indian Association of Dermatologists, Venereologists and Leprologists (IADVL) assigned the task of preparing these recommendations to its task force on PRP. A comprehensive literature search was done in the English language on the preparation of PRP across multiple databases. The grade of evidence and strength of recommendation was evaluated on the GRADE framework (Grading of Recommendation, Assessment, Development and Evaluation). A draft of clinical recommendations was developed on the best available evidence which was also scrutinized and critically evaluated by the IADVL Academy of Dermatology. Based on the inputs received, this final consensus statement was prepared. A total of 45 articles (meta-analyses, prospective and retrospective studies, reviews [including chapters in books], and case series) were critically evaluated and the evidence thus gathered was used in the preparation of these recommendations. This expert group recommends the use of double-spin manual method for the preparation of PRP. The recommended parameters for centrifuge are 100–300 g for 5–10 min for the first spin and 400–700 g for 10–17 min for the second spin. The recommended platelet concentration in PRP for the treatment of various dermatological conditions is 1–1.5 million platelets/μL. The activation of PRP is not required when it is injected into soft tissues.

[Optimized preparation method of leukocytes-rich platelet-rich plasma by varying conditions during centrifugation]

OBJECTIVE

To identify a more popularized preparation protocol of leukocytes-rich platelet-rich plasma (L-PRP) for higher tolerance rate.

METHODS

The peripheral blood samples of 76 volunteers (45.0 mL/case) were mixed with 5 mL sodium citrate injection for blood transfusion, and L-PRP was prepared by twice centrifugations. All blood samples were divided into three groups according to the parameters of twice centrifugation: experimental group A (12 cases, 400× g, 10 minutes for the first time and 1 100× g, 10 minutes for the second time), experimental group B (27 cases, 800× g, 10 minutes for the first time and 1 100× g, 10 minutes for the second time), and control group (37 cases, 1 360× g, 10 minutes for the first time and 1 360× g, 10 minutes for the second time). The platelet recovery rate and platelet and leukocyte enrichment coefficient of L-PRP in each group were calculated and compared.

RESULTS

After removal of abnormal blood samples (platelet recovery rate was more than 100% or white thrombus), the remaining 55 cases were included in the statistical analysis, including 10 cases in experimental group A, 21 cases in experimental group B, and 24 cases in control group. The platelet enrichment coefficient and platelet recovery rate of experimental group B were significantly higher than those of experimental group A and control group ( P<0.05); there was no significant difference between experimental group A and control group ( P>0.05). There was no significant difference in leukocyte enrichment coefficient between experimental groups A, B, and control group ( P>0.05).

CONCLUSION

The preparation quality of PRP is affected by various factors, including centrifugal force, centrifugal time, temperature, and operation process, etc. Twice centrifugation (800× g, 10 minutes for the first time and 1 100× g, 10 minutes for the second time) is an ideal and feasible centrifugation scheme, which can obtain satisfactory platelet recovery rate and enrichment coefficient with thicker buffy coat, which can reduce the fine operation requirements for operators, improve the fault tolerance rate and generalization.

Optimization of a rapid one-step platelet-rich plasma preparation method using syringe centrifugation with and without carprofen

Background

Carprofen and platelet-rich plasma (PRP) are widely used in small animal clinical practice. Separation layers have been used during blood centrifugation to increase platelet yield. The objectives of this study were to (1) identify the optimal centrifugation force for the one-step PRP preparation, (2) determine whether there is an advantage to using carprofen in one-step PRP preparation, and (3) compare platelet morphology from one-step PRP preparation with and without carprofen. We hypothesized that injectable carprofen (emulsion formula) could be used successfully as the separation layer in PRP preparation.

Results

Samples from 14 healthy dogs were used to determine the optimal centrifugation force using one-step PRP preparation in a disposable syringe without carprofen, with forces set at 300, 500, 700, 900, 1100, 1300, and 1500 xg for 5 min. Optimum centrifugation force, plasma volume, and platelet concentrations of one-step PRP preparation were found and recovered at 900 xg, 1.9 ± 0.28 ml, and 260.50 ± 58.39 X 10³ cell/μl, respectively. Samples from 12 healthy dogs were used to determine the optimal force (with forces set at 300, 500, 700, and 900 xg) for 5 min using one-step PRP preparation with carprofen. Optimum centrifugation force, plasma volume, and platelet concentrations for one-step PRP preparation with carprofen were found and recovered at 500 xg, 0.62 ± 0.16 ml and 948.50 ± 261.40 X 10³ cell/μl, respectively. One-step PRP preparation with carprofen increased the platelet yield from baseline by 1.76 and 4.95 fold, respectively. Samples from 3 healthy dogs were used to observe platelet morphologies after centrifugation by scanning electron microscopy. Images of platelets on glass slides from both preparation methods revealed pseudopods emerging from the margins of the discoid platelets.

Conclusions

One-step PRP centrifugation both with and without carprofen increased the platelet yield, but using carprofen (emulsion formula) as a separation layer resulted in a higher platelet yield. The clinical usefulness of PRP products from these methods should be further investigated.

Platelet-rich plasma and regenerative dentistry

Regenerative dentistry is an emerging field of medicine involving stem cell technology, tissue engineering and dental science. It exploits biological mechanisms to regenerate damaged oral tissues and restore their functions. Platelet‐rich plasma (PRP) is a biological product that is defined as the portion of plasma fraction of autologous blood with a platelet concentration above that of the original whole blood. A super‐mixture of key cytokines and growth factors is present in platelet granules. Thus, the application of PRP has gained unprecedented attention in regenerative medicine. The rationale underlies the utilization of PRP is that it acts as a biomaterial to deliver critical growth factors and cytokines from platelet granules to the targeted area, thus promoting regeneration in a variety of tissues. Based on enhanced understanding of cell signalling and growth factor biology, researchers have begun to use PRP treatment as a novel method to regenerate damaged tissues, including liver, bone, cartilage, tendon and dental pulp. To enable better understanding of the regenerative effects of PRP in dentistry, this review describes different methods of preparation and application of this biological product, and provides detailed explanations of the controversies and future prospects related to the use of PRP in dental regenerative medicine.

A topical cell therapy approach for diabetic chronic ulcers: Effects of mesenchymal stromal cells associated with platelet-rich plasma

BACKGROUND

Diabetic cutaneous ulcers are subjected to several physiological and biochemical defects, which contribute to wound chronicity and therapeutic failure. Platelet-rich plasma (PRP) has been used for stimulating tissue regeneration, and mesenchymal stromal cells (MSCs) have demonstrated therapeutic properties in all phases of skin regeneration in cell therapy studies.

AIMS

The objective of this study was to evaluate the therapeutic effects related to the use of a biomembrane composed of autologous MSCs and PRP on chronic wounds of diabetic patients (pre-post pilot study).

PATIENTS/METHODS

Six diabetic patients with chronic wounds for more than 6 months were subjected to adipose tissue collection for isolation of MSCs, blood collection for PRP preparation, and topical administration of a biomembrane of MSCs and PRP on each chronic wound. The statistical difference regarding the evolution of ulcers was calculated by means of paired t test.

RESULTS

There was granulation tissue formation starting from 7 days after topical application. Total re-epithelialization occurred in 5 of the 9 lesions treated, and the mean wound healing rate (WHR) was 74.55% (±32.55%) after 90 days. No cicatricial hypertrophy or retraction was observed.

CONCLUSION

Mesenchymal stromal cells topical therapy associated with PRP is well-tolerated and able to provide a reduction in ulcer area of diabetic chronic wounds.

Synergistic Effects of Human Platelet-Rich Plasma Combined with Adipose-Derived Stem Cells on Healing in a Mouse Pressure Injury Model

Pressure injury (PI) affects quality of life and results in economic and social burdens. Local transplantation of human adipose-derived stem cells (ASCs) is considered an effective treatment. However, ASC suspension alone is vulnerable to the immune system and results in a shortened cell survival. There is increasing evidence of a synergistic effect of platelet-rich plasma (PRP) combined with ASCs on wound healing. This study investigated the effectiveness, synergy, and mechanism of wound healing following local injection of PRP combined with ASCs in a rodent PI model. PRP or ASCs alone were the control intervention. Wound healing, inflammatory infiltration, collagen deposition, angiogenesis, neurogenesis, and cell homing were investigated. PI healing was promoted by the synergistic effects of PRP combined with ASCs. The combination was more effective than ASCs alone for modulating inflammation, increasing collagen deposition, angiogenesis, neurogenesis, and the persistence of the injected ASCs. These data provide a theoretical foundation for the clinical administration of ASCs combined with PRP in PI healing and skin regeneration.

The anti-inflammatory effect of the platelet-rich plasma in the periodontal pocket

Objective

Chronic periodontitis (CP) is a common inflammatory disease that causes destruction to the supporting tissues of the teeth. Many treatment modalities tried to stop the disease progression. Platelet-rich plasma (PRP) is one of the regenerative methods that used in adjunct to conventional periodontal treatment. The aim of this study was to evaluate the anti-inflammatory effect of PRP by monitoring the lymphocyte count before and after its application to the periodontal pocket.

Materials and Methods

Twenty patients, with CP and a pocket depth equal to or deeper than 4 mm, subjected to scaling, root planing, and PRP injection into the pocket. The lymphocyte count measured before and after 1 month from PRP application. Clinical periodontal parameters were taken during two visits (1 month apart), with customized stent fabrication.

Results

All clinical periodontal parameters showed a reduction in their value following 1 month of PRP application. There was a noticeable reduction in lymphocyte count from (mean 2.47 ± 0.91) to (mean 1.94 ± 0.77).

Conclusion

In addition to its traditional uses, PRP has a great role in the periodontal treatment by its anti-inflammatory effect.

Effect of platelet-rich plasma on peri-implant trabecular bone volume and architecture: A preclinical micro-CT study in beagle dogs

OBJECTIVES

To evaluate the peri-implant trabecular bone volume and architecture changes with 6-month follow-up after local application of platelet-rich plasma (PRP) and platelet-poor plasma (PPP) using high-resolution micro-CT.

MATERIAL AND METHODS

Seventy-two dental implants were placed into healed mandibular sites of 9 beagle dogs. Implants were randomly divided into 4 groups following a split-mouth design: control I; control II; PPP; and PRP. Primary and secondary stabilities were assessed using resonance frequency analyses. At 1, 3, and 6 months after implant loading, trabecular structural parameters were evaluated at 0.5, 1, and 1.5 mm away from implants using micro-CT (voxel = 20 μm).

RESULTS

Primary and secondary stabilities were equivalent in all conditions. PPP and PRP groups showed higher bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) but lower trabecular separation (Tb.Sp) and total porosity percentage (Po (tot)) at all 3 time points. A significant decrease in BV/TV and Tb.Th was found for the control groups after 3 months of healing, while this was not observed in both the PPP and PRP groups. However, no distinct difference was found between the PRP and PPP groups over time. Moreover, as the investigated distance from the implant surface increased, BV/TV and Po (tot) within the same group and time point stayed the same, yet Tb.Th and Tb.Sp continued to increase.

CONCLUSIONS

Platelet-rich plasma and PPP with conventional implant placement lead to similar primary and secondary implant stability, but improved peri-implant bone volume and structural integration. The present research does not seem to suggest a different bone remodeling pattern when using PRP or PPP.

From Platelet-Rich Plasma to Advanced Platelet-Rich Fibrin: Biological Achievements and Clinical Advances in Modern Surgery

In the past 20 years, the platelet concentrates have evolved from first-generation products, i.e., platelet-rich plasma (PRP) and plasma rich in growth factors to the second-generation products such as leukocyte-platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF). These autologous products with a higher leukocyte inclusion and flexible fibrin mesh act as a scaffold to increase cellular migration in the angiogenic, osteogenic, and antimicrobial potential of these biomaterials in tissue regeneration. In the second-generation platelet concentrates, the protocols are easier, cheaper, and faster with an entire physiological fibrin matrix, resulting in a tridimensional mesh, not as rigid as one of the first generations. This allows the slow release of molecules over a longer period of time and triggers the healing and regenerative process at the site of injury. The potential of A-PRF to mimic the physiology and immunology of wound healing is also due to the high concentration of growth factors released as follows: vascular endothelial growth factor, platelet-derived growth factor, transforming growth factor-β, and anti-inflammatory cytokines that stimulate tissue cicatrization, vessels formation, and bone cell proliferation and differentiation. Furthermore, the number of neutrophils and monocytes/macrophages is higher releasing important chemotactic molecules such as chemokine ligand-5 and eotaxin. Thus, L-PRF and A-PRF have been used, especially in implantology, periodontology, and maxillofacial surgery. Future clinical applications include tissue regeneration/grafts, ulcers/skin necrosis in the diabetic patient and others, plastic surgery, and even musculoskeletal lesions.

Platelet-rich plasma affects the proliferation of canine bone marrow-derived mesenchymal stromal cells in vitro

BACKGROUND

Reported efficacy of platelet-rich plasma (PRP) in regenerative medicine is contradictory. We validated the effects of PRP on proliferation of canine bone marrow-derived multipotent mesenchymal stromal cells (K9BMMSCs) in vitro. PRP was extracted from blood of six dogs with osteoarthritis. K9BMMSCs were established from bone marrow and characterized for CD90 and CD19 expression by immunocytochemistry. Effects of PRP concentrations on viability of matching autologous K9BMMSCs were validated using MTS assay.

RESULTS

Positive CD90 and negative CD19 expression confirmed MSC origin. PRP at 40% volume/volume concentration increased, while PRP at 80 and 100% v/v concentrations suppressed viability of tested K9BMMSCs.

CONCLUSION

PRP concentration plays an important role in K9BMMSCs viability, which could affect tissue repairs in vivo.

Incorporation of Fibrin Matrix into Electrospun Membranes for Periodontal Wound Healing

Guided tissue regeneration (GTR) aims to regenerate the lost attachment apparatus caused by periodontal disease through the use of a membrane. The goal of this study is to create and characterize a novel hybrid membrane that contains biologically active fibrin matrix within a synthetic polycaprolactone (PCL) electrospun membrane. Three-dimensional fibrin matrices and fibrin-incorporated electrospun membrane were created from fresh frozen plasma by centrifugation in glass vials under three different conditions: 400 g for 12 min, 1450 g for 15 min and 3000 g for 60 min. Half the membranes were crosslinked with 1% genipin. Degradation against trypsin indicated biologic stability while uniaxial tensile testing characterized mechanical properties. Continuous data was analyzed by ANOVA to detect differences between groups (p = 0.05). Fibrin-incorporated electrospun membranes showed statistically significant increase in mechanical properties (elastic modulus, strain at break and energy to break) compared to fibrin matrices. While crosslinking had marginal effects on mechanical properties, it did significantly increase biologic stability against trypsin (p < 0.0001). Lastly, membranes generated at 400 g and 1450 g were superior in mechanical properties and biologic stability compared to those generated at 3000 g. Fibrin-incorporated, crosslinked electrospun PCL membranes generated at lower centrifugation forces offers a novel strategy to generate a potentially superior membrane for GTR procedures.

Application of standardized platelet-rich plasma in elderly patients with complex wounds

In recent years, autologous platelet-rich plasma (PRP) derivatives have been used widely in the regeneration and repair of tissue, but a standard definition and preparation method for PRP are lacking. We developed a standardized method using platelet indices as quality-control indicators for PRP preparation. Twenty-one elderly patients (9 males, 12 females) with complex wounds were treated with standardized platelet-rich plasma (S-PRP). The platelet count in PRP after the second centrifugation was 1,069-1,436 × 10⁹ /L. We adjusted the platelet concentration in PRP after a second centrifugation to 1,000 × 10⁹ /L according to a formula using platelet-poor plasma (PPP). The standardized preparation method that we developed gave S-PRP with a relatively uniform platelet concentration. The wounds of 21 patients showed accelerated healing after S-PRP treatment, and there were no obvious side effects during treatment. These data suggest that our preparation method of S-PRP, using platelet indices as quality-control indicators with platelet count of 1,000 × 10⁹ /L could be used for the treatment of complex wounds in the elderly. The preparation method of S-PRP proposed in the present study may be a simple and effective method of PRP quality control.

Problems and Solutions for Platelet-Rich Plasma in Facial Rejuvenation: A Systematic Review

BACKGROUND

In recent years, platelet-rich plasma (PRP) has been widely applied in orthopedics, maxillofacial surgery, burns, and plastic surgery, especially in facial rejuvenation. Research is ongoing into new indications and mechanisms of PRP to promote its wider, safer, and more effective use in the clinic. This article reviews the possible mechanisms of PRP in facial rejuvenation and related research. It is expected that the application of PRP in this field will increase.

METHODS

The use of PRP in facial rejuvenation was screened using inclusion and exclusion criteria. The relevant articles were searched through Pubmed digest database, SCI full-text database, ScienceDirect full-text database, and the CNKI full-text database. The different effects and limitations of PRP were extracted.

RESULTS

A total of 108 articles were obtained, including 18 articles researching PRP in cells, 10 articles on animal research using PRP, 16 articles on the clinical study of PRP, 24 articles involving signs of skin aging, and four articles on the limitations of PRP. The remaining articles were related to the preparation of PRP, the introduction of PRP, and other aspects.

CONCLUSION

Based on in vitro and in vivo research, PRP may play a role in promoting tissue regeneration, oxidative stress and revascularization, which form the theoretical basis for the use of PRP in the clinical treatment of facial rejuvenation.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Turn down - turn up: a simple and low-cost protocol for preparing platelet-rich plasma

OBJECTIVE

To describe and analyze a new protocol for the extraction of platelet-rich plasma (PRP) for use in clinical practice and compare this technique with methods that have been previously described in the medical literature.

METHODS

We extracted PRP from 20 volunteers using four different protocols (single spin at 1600 ×g, single spin at 600 ×g, double spin at 300 and 700 ×g, and double spin at 600 and 900 ×g). In another group of 12 individuals, we extracted PRP with our new technique (named 'turn down-turn up') consisting of a double spin (200 ×g and 1600 ×g) closed system using standard laboratory equipment (including an ordinary benchtop centrifuge), where the blood remained in the same tube during all processes, reducing the risk of contamination. Platelet counts adjusted to baseline values were compared using analysis of covariance (ANCOVA).

RESULTS

Using the four previously described protocols (mentioned above), we obtained concentrations of platelets that were 1.15-, 2.07-, 2.18-, and 3.19-fold greater than the baseline concentration, respectively. With the turn down-turn up technique, we obtained a platelet count that was 4.17-fold (95% confidence interval (CI): 3.09 to 5.25) greater than the baseline platelet count (p=0.063 compared with the double spin at 600 and 900 ×g method). The total cost of the disposable materials used in the extraction process was less than US$10.00 per individual.

CONCLUSION

In the present study, we described a simple and safe method for obtaining PRP using low-cost devices.

Current clinical applications of platelet-rich plasma in various gynecological disorders: An appraisal of theory and practice

The purpose of this paper is to review the current clinical uses of platelet-rich plasma (PRP) in the field of gynecology. All relevant articles published from January 2000 to December 2017 were reviewed and analyzed. The articles on PRP in the field of gynecology were mainly case series, pilot studies, or case reports. PRP is currently considered a new therapeutic modality for some disorders that are refractory to conventional drugs.

[Effect of human adipose-derived stem cells on pressure ulcer healing in mouse]

Objective

To investigate the effect of human adipose-derived stem cells (hADSCs) on pressure ulcers in mouse.

Methods

The subcutaneous adipose tissue from voluntary donation was harvested. Then the hADSCs were isolated and cultured by mechanical isolation combined with typeⅠcollagenase digestion. The 3rd generation cells were identified by osteogenic, adipogenic, chondrogenic differentiations and flow cytometry. The platelet rich plasma (PRP) from peripheral blood donated by healthy volunteers was prepared by centrifugation. The pressure ulcer model was established in 45 C57BL/6 mice by two magnets pressurized the back skin, and randomly divided into 3 groups ( n=15). The wounds were injected with 100 μL of hADSCs (1×10 ⁶ cells) transfected with a green fluorescent protein (GFP)-carrying virus, 100 μL human PRP, and 100 μL PBS in hADSCs group, PRP group, and control group, respectively. The wound healing was observed after injection. The wound healing rate was calculated on the 5th, 9th, and 13th days. On the 5th, 11th, and 21st day, the specimens were stained with HE staing, Masson staining, and CD31 and S100 immunohistochemical staining to observe the vascular and nerve regeneration of the wound. In hADSCs group, fluorescence tracer method was used to observe the colonization and survival of the cells on the 11th day.

Results

The cultured cells were identified as hADSCs by induced differentiation and flow cytometry. The platelet counting was significantly higher in PRP group than in normal peripheral blood group ( t=5.781, P=0.029). General observation showed that the wound healing in hADSCs group was superior to those in PRP group and control group after injection. On the 5th, 9th, and 13th days, the wound healing rate in hADSCs group was significantly higher than those in PRP group and control group ( P<0.05). Histological observation showed that compared with PRP group and control group, inflammatory cell infiltration and inflammatory reaction were significantly reduced in hADSCs group, collagen deposition was significantly increased, and skin appendage regeneration was seen on the 21st day; at each time point, the expression of collagen was significantly higher in hADSCs group than in PRP group and control group ( P<0.05). Immunohistochemical staining showed that the number of neovascularization and the percentage of S100-positive cells in hADSCs group were significantly better than those in PRP group and control group on the 5th, 9th, and 13th days ( P<0.05). Fluorescent tracer method showed that the hADSCs could colonize the wound and survive during 11 days after injection.

Conclusion

Local transplantation of hADSCs can accelerate healing of pressure ulcer wounds in mice and improve healing quality by promoting revascularization and nerve regeneration.

Theoretical prediction and validation of cell recovery rates in preparing platelet-rich plasma through a centrifugation

In the present study, we propose a theoretical framework to predict the recovery rates of platelets and white blood cells in the process of centrifugal separation of whole blood contained in a tube for the preparation of platelet-rich plasma. Compared to previous efforts to optimize or standardize the protocols of centrifugation, we try to further the physical background (i.e., based on the multiphase flow phenomena) of analysis to develop a universal approach that can be applied to widely different conditions. That is, one-dimensional quasi-linear partial differential equation to describe the centrifugal sedimentation of dispersed phase (red and white blood cells) in continuous phase (plasma) is derived based on the kinematic-wave theory. With the information of whole blood volume and tube geometry considered, it is possible to determine the positions of interfaces between supernatant/suspension and suspension/sediment, i.e., the particle concentration gradient in a tube, for a wide range of centrifugation parameters (time and acceleration). While establishing a theory to predict the recovery rates of the platelet and white blood cell from the pre-determined interface positions, we also propose a new correlation model between the recovery rates of plasma and platelets, which is found to be a function of the whole blood volume, centrifugal time and acceleration, and tube geometry. The present predictions for optimal condition show good agreements with available human clinical data, obtained from different conditions, indicating the universal applicability of our method. Furthermore, the dependence of recovery rates on centrifugal conditions reveals that there exist a different critical acceleration and time for the maximum recovery rate of platelets and white blood cells, respectively. The other parameters such as hematocrit, whole blood volume and tube geometry are also found to strongly affect the maximum recovery rates of blood cells, and finally, as a strategy for increasing the efficiency, we suggest to dilute the whole blood, increase the whole blood volume with a tube geometry fixed.

Current Evidence for Clinical Efficacy of Platelet Rich Plasma in Aesthetic Surgery: A Systematic Review

Background

Platelet rich plasma (PRP) has attracted attention in a number of surgical fields due to a wide variety of potential clinical benefits. Yet PRP has not gained wide popularity in aesthetic surgery as a result of uncertainty surrounding objective clinical evidence.

Objectives

We aim to describe the current applications, define preparation and activation, explore effectiveness, and propose a classification system to facilitate comparisons across studies.

Methods

A comprehensive review of the literature regarding the use of platelet rich plasma in aesthetic surgery was performed. Data gathered included: PRP application, study type, subject number, centrifugation, anticoagulation, activation, PRP composition, and outcomes.

Results

Thirty-eight reports were identified. Applications included injection into aging skin (29%), scalp alopecia (26%), lipofilling (21%), fractional laser (13%), and facial surgery (11%). The majority of studies (53%) were case series without controls. Leucocytes were sparsely defined (32%). The concentration of injected and/or baseline platelets was rarely clarified (18%). The mechanism of activation was described in 27 studies (71%), while anticoagulation was uncommonly elucidated (47%). While most studies (95%) claim effectiveness, objective measures were only utilized in 17 studies (47%).

Conclusions

Current studies produce context-dependent results with a lack of consistent reporting of PRP preparation, composition, and activation in aesthetic applications, making meaningful meta-analysis unrealistic. Thus the method of PRP preparation warrants increased attention. We recommend a set of descriptors, FIT PAAW (described below), to produce scientifically grounded conclusions, facilitating a clearer understanding of the situations in which PRP is effective.

Level of Evidence

4

Concise Review: The Use of Adipose-Derived Stromal Vascular Fraction Cells and Platelet Rich Plasma in Regenerative Plastic Surgery

Tissue engineering has emerged at the intersection of numerous disciplines to meet a global clinical need for technologies to promote the regeneration of tissues. Recently, many authors have focused their attention on mesenchymal stem/stromal cells (MSCs) for their capacity to differentiate into many cell lineages. The most widely studied cell types are bone marrow mesenchymal stem cells and adipose-derived stem cells (ASCs), which display similar results. Biomaterials, cells, and growth factors are needed to design a regenerative plastic surgery approach in the treatment of organ and tissue defects, but not all tissues are created equal. The aim of this article is to describe the advances in tissue engineering through the use of ASCs, platelet rich plasma, and biomaterials to enable regeneration of damaged complex tissue. Stem Cells 2017;35:117-134.

Platelet-rich plasma (PRP) and adipose-derived mesenchymal stem cells: stimulatory effects on proliferation and migration of fibroblasts and keratinocytes in vitro

The clinical use of tissue engineering associated with cell therapy is considered a new alternative therapy for the repair of chronic lesions with potential application in different medical areas, mostly in orthopedic and dermatological diseases. Platelet-rich plasma (PRP) is a rich source of growth factors and cytokines important for wound healing. Adipose-derived mesenchymal stem cells (ADSCs) have shown potential to accelerate the resolution of ulcers, to stimulate cell proliferation, and to benefit the quality of skin repair. This study aims to determine the effect of PRP and conditioned medium (CM) from ADSC on fibroblast and keratinocyte proliferation in vitro. Migration and proliferation assays were performed to evaluate the growth of fibroblasts and keratinocytes in the presence of PRP, CM, and CM + PRP. Significant proliferative stimulation was observed after 48 h of culture (p < 0.05) on mean absorbance of fibroblasts cultured with 10 and 25 % PRP, 100 % CM, and 25 % PRP + 25 % CM, if compared with control. Keratinocyte proliferation was stimulated after 48 h in cultures with 25, 50, and 100 % CM, and growth was compared with controls. The migration assay detected a significant migratory stimulus in fibroblasts cultured with 10 % PRP + 10 % CM after 48 h. These in vitro results suggest that PRP and ADSC have therapeutic potential for healing and re-epithelialization of chronic wounds in vivo.

In vitro study of the role of thrombin in platelet rich plasma (PRP) preparation: utility for gel formation and impact in growth factors release

Introduction: The use of PRP has been studied for different fields, with promising results in regenerative medicine. Until now, there is no study in the literature evaluating thrombin levels in serum, used as autologous thrombin preparation. Therefore, in the present study we evaluated the role played by different thrombin concentrations in PRP and the impact in the release of growth factors. Also, different activators for PRP gel formation were evaluated. Methods: Thrombin levels were measured in different autologous preparations: serum, L-PRP (PRP rich in leukocytes) and T-PRP (thrombin produced through PRP added calcium gluconate). L-PRP was prepared according to the literature, with platelets and leukocytes being quantified. The effect of autologous thrombin associated or not with calcium in PRP gel was determined by measuring the time of gel formation. The relationship between thrombin concentration and release of growth factors was determined by growth factors (PDGF-AA, VEGF and EGF) multiplex analysis. Results: A similar concentration of thrombin was observed in serum, L-PRP and T-PRP (8.13 nM, 8.63 nM and 7.56 nM, respectively) with a high variation between individuals (CV%: 35.07, 43 and 58.42, respectively). T-PRP and serum with calcium chloride showed similar results in time to promote gel formation. The increase of thrombin concentrations (2.66, 8 and 24 nM) did not promote an increase in growth factor release. Conclusions: The technique of using serum as a thrombin source proved to be the most efficient and reproducible for promoting PRP gel formation, with some advantages when compared to other activation methods, as this technique is easier and quicker with no need of consuming part of PRP. Noteworthy, PRP activation using different thrombin concentrations did not promote a higher release of growth factors, appearing not to be necessary when PRP is used as a suspension.

Cytokine-release kinetics of platelet-rich plasma according to various activation protocols

Objectives

This study was conducted to evaluate the cytokine-release kinetics of platelet-rich plasma (PRP) according to different activation protocols.

Methods

Two manual preparation procedures (single-spin (SS) at 900 g for five minutes; double-spin (DS) at 900 g for five minutes and then 1500 g for 15 minutes) were performed for each of 14 healthy subjects. Both preparations were tested for platelet activation by one of three activation protocols: no activation, activation with calcium (Ca) only, or calcium with a low dose (50 IU per 1 ml PRP) of thrombin. Each preparation was divided into four aliquots and incubated for one hour, 24 hours, 72 hours, and seven days. The cytokine-release kinetics were evaluated by assessing PDGF, TGF, VEGF, FGF, IL-1, and MMP-9 concentrations with bead-based sandwich immunoassay.

Results

The concentration of cytokine released from PRP varied over time and was influenced by various activation protocols. Ca-only activation had a significant effect on the DS PRPs (where the VEGF, FGF, and IL-1 concentrations were sustained) while Ca/thrombin activation had effects on both SS and DS PRPs (where the PDGF and VEGF concentrations were sustained and the TGF and FGF concentrations were short). The IL-1 content showed a significant increase with Ca-only or Ca/thrombin activation while these activations did not increase the MMP-9 concentration.

Conclusion

The SS and DS methods differed in their effect on cytokine release, and this effect varied among the cytokines analysed. In addition, low dose of thrombin/calcium activation increased the overall cytokine release of the PRP preparations over seven days, relative to that with a calcium-only supplement or non-activation.

Cite this article: Professor J. H. Oh. Cytokine-release kinetics of platelet-rich plasma according to various activation protocols. Bone Joint Res 2016;5:37–45. DOI: 10.1302/2046-3758.52.2000540

Comparison of the Cellular Composition and Cytokine-Release Kinetics of Various Platelet-Rich Plasma Preparations

BACKGROUND

Variations in formulations used to prepare platelet-rich plasmas (PRPs) result in differences in the cellular composition and biomolecular characteristics.

PURPOSE

To evaluate the cellular composition and the cytokine-release kinetics of PRP according to differences in the preparation protocols.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five preparation procedures were performed for 14 healthy subjects, including 2 manual procedures (single-spin [SS] at 900 g for 5 minutes; double-spin [DS] at 900 g for 5 minutes and then 1500 g for 15 minutes) and 3 methods with commercial kits (Arthrex ACP, Biomet GPS, and Prodizen Prosys). After evaluation of cellular composition, each preparation was divided into 4 aliquots and incubated for 1 hour, 24 hours, 72 hours, and 7 days for the assessment of cytokine release over time. The cytokine-release kinetics were evaluated by assessing platelet-derived growth factor (PDGF), transforming growth factor (TGF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), interleukin-1 (IL-1), and matrix metalloproteinase-9 (MMP-9) concentrations of each aliquot with bead-based sandwich immunoassay.

RESULTS

The DS PRP had a higher concentration of platelets and leukocytes than did the SS PRP. Every PRP preparation exhibited an increase in PDGF, TGF, VEGF, and FGF release when compared with whole blood samples. The FGF and TGF release occurred quickly and decreased over time, while the PDGF and VEGF release was constant and sustained over 7 days. The PDGF and VEGF concentrations were higher in the DS PRP than in the SS PRP, whereas the TGF and FGF concentrations were higher in the SS PRP than in the DS PRP. Biomet GPS had the highest VEGF and MMP-9 concentrations but the lowest TGF concentration. Arthrex ACP had the highest FGF concentration but the lowest PDGF concentration. Prodizen Prosys had the highest IL-1 concentration and higher PDGF concentration than Arthrex ACP.

CONCLUSION

The DS method generally led to a higher concentration of platelet relative to the SS method. However, the cytokine content was not necessarily proportional to the cellular composition of the PRPs, as the greater content could be different between the SS or DS method depending on the type of cytokine.

CLINICAL RELEVANCE

Physicians should select proper PRP preparations after considering their biomolecular characteristics and patient indications.