Platelet-rich plasmas: growth factor content and roles in wound healing

Effects of intrauterine infusion of autologous platelet-rich plasma gel on endometrial thickness and outcomes of frozen-thawed embryo transfer in women with thin endometrium

PURPOSE

The purpose of this study is to determine whether intrauterine infusion of autologous platelet-rich plasma (PRP) gel increases endometrial thickness (EMT) and improves the outcomes of frozen-thawed embryo transfer (FET) in women with thin endometrium.

METHODS

This study included 111 women (aged 25-44 years) who had thin endometrium. All patients had at least one previous cycle canceled because of thin endometrium or previous embryo transfer cycles and an EMT < 7 mm. Forty-seven women underwent intrauterine infusion of autologous PRP gel on three occasions during endometrial preparation and the remaining women served as controls. The final EMT was measured by ultrasound before the start of the luteal phase, and FET-related outcome parameters were monitored.

RESULTS

Mean EMT was greater in women who received PRP gel than in those who did not (6.7 mm vs. 6.3 mm, respectively, p < 0.05). FET was attempted in all women. The 47 women who underwent infusion of PRP had a significantly higher pregnancy rate (18 pregnancies (38.3%), with 17 (36.2%) ongoing) compared with 64 control women (ten pregnancies (18.5%), nine (16.7%) ongoing). However, there was no significant reduction in the miscarriage rate.

CONCLUSION

Intrauterine infusion of autologous PRP gel during endometrial preparation for FET cycles can improve the EMT, clinical pregnancy rate, and ongoing pregnancy rate in women with thin endometrium.

Engineering of Bioresorbable Polymers for Tissue Engineering and Drug Delivery Applications

Herein, the recent advances in the development of resorbable polymeric-based biomaterials, their geometrical forms, resorption mechanisms, and their capabilities in various biomedical applications are critically reviewed. A comprehensive discussion of the engineering approaches for the fabrication of polymeric resorbable scaffolds for tissue engineering, drug delivery, surgical, cardiological, aesthetical, dental and cardiovascular applications, are also explained. Furthermore, to understand the internal structures of resorbable scaffolds, representative studies of their evaluation by medical imaging techniques, e.g., cardiac computer tomography, are succinctly highlighted. This approach provides crucial clinical insights which help to improve the materials' suitable and viable characteristics for them to meet the highly restrictive medical requirements. Finally, the aspects of the legal regulations and the associated challenges in translating research into desirable clinical and marketable materials of polymeric-based formulations, are presented.

Non-surgical pain management for hip joint disease in veterinary medicine

The most common orthopaedic developmental disease in dogs is hip dysplasia. This condition results in coxofemoral laxity due to incongruity and lack of stabilisation of the joint by the soft tissues. Currently, there is no therapeutic plan to correct hip dysplasia without surgical intervention at a very early age. The goal of the non-surgical treatment is to relieve pain and stiffness and to increase the muscle strength, usually through hydrotherapy and the beneficial physical properties of water. Recently, there has been growing interest in regenerative medicine, which involves the use of mesenchymal stem cells (MSCs) and their products to alleviate the characteristic clinical symptoms of osteoarthritis (OA). In vivo studies with canine MSCs have shown that an intra-articular injection of MSCs into cartilage lesions leads to the excellent regeneration of the hyaline cartilage. Regenerative medicine has undergone rapid development in recent years thanks to new therapies based on the application and combination of innovative biomaterials. One of the first known regenerative methods to be used in clinical practice was platelet-rich plasma (PRP). This review summarises the use and potential of MSCs and PRP, including their in vitro properties, their therapeutic effects in the treatment of cartilage lesions in preclinical in vivo studies, their clinical efficacy in the treatment of naturally occurring OA in dogs, and the current limitations of the studies.

The impact of submucosal PRP injection on wound healing after endoscopic sinus surgery: a randomized clinical trial

PURPOSE

Chronic rhinosinusitis (CRS) is a prevalent chronic disease observed on a global scale. The utilization of endoscopic sinus surgery (ESS) has gained significant recognition as an effective intervention for individuals with CRS and nasal polyps who have not responded to conventional treatments. The need (or not) for revision surgery frequently relies on the promotion of optimal wound healing. The impact of platelet-rich plasma (PRP) on tissue healing has been extensively examined in various surgical fields.

METHODS

The present prospective study involved 30 patients suffering with nasal polyposis who underwent endoscopic sinus surgery. 15 patients were assigned to the PRP group, and 15 patients to the control group. The clinical follow-up of the patients took place at specific intervals, at weeks 1, 2, 3, 4, 8, and 12 after the surgical procedure. The evaluator identified the existence of adhesions, crusting, bleeding, granulation and infection using a visual analogue scale score. The patients also completed the SNOT 22 questionnaire prior to surgery and at each postoperative visit.

RESULTS

The present study observed a lower incidence of adhesion, infection, hemorrhage and granulation in the PRP group. Furthermore, a statistically significant difference was detected between the groups.

CONCLUSION

Based on the findings of the present investigation, it seems that platelet-rich plasma (PRP) is beneficial on wound healing during the early stages following the surgical procedure. The technique is characterized by its limited invasiveness, which contributes to its low risk profile and the achievement of clinically good outcomes.

Cellulase-assisted platelet-rich plasma release from nanofibrillated cellulose hydrogel enhances wound healing

Platelet-rich plasma (PRP) is a source of growth factors, which are implicated in active tissue regeneration. However, after transplantation the efficacy of these bioactive compounds is often diminished due to rapid degradation and untargeted localization. For this reason, we evaluated the potential of nanofibrillated cellulose (NFC) hydrogel as a PRP carrier. NFC hydrogel is an animal-free biomaterial that, when doped with cellulase, can assist the release of PRP in a wound site. In this study, we examined the effects of 0.5% (m/v) NFC hydrogel formulations, including PRP and cellulase, on the migration and proliferation of skin cells via an in vitro scratch wound model. The suitability of the 0.8% NFC hydrogel formulations for accelerated wound healing and PRP carrying was studied in vitro in diffusion studies and in vivo in a full-thickness excisional wound model in SKH1 mice. None of the NFC hydrogel formulations with or without PRP and cellulase disturbed the normal cell behavior in vitro, and cellulase was successfully used to degrade NFC. NFC hydrogel slowed fibroblast migration rate in vitro. In vivo, NFC hydrogel treatment showed significantly enhanced re-epithelialization compared to control and supported collagen deposition. In addition, angiogenesis was significantly induced via PRP release after degrading NFC hydrogel with cellulase without abnormal host reaction. This study demonstrates the potential of NFC hydrogel with cellulase as a carrier for PRP with controlled release in future skin tissue engineering applications.

Persistent pneumothorax treatment following congenital cardiac surgery by platelet-fibrin glue

Persistent pneumothorax is a life-threatening complication that can occur after congenital cardiac surgery. Traditional treatment such as chest tube drainage may not be effective in managing this condition. This study presents a new minimally invasive method for treating persistent pneumothorax using platelet-rich plasma-fibrin glue (PRP-FG). The method has been successful in treating postoperative chylothorax in previous studies, and its use has decreased morbidity, mortality, and hospital stay in chylothorax patients. Ten patients with persistent pneumothorax following cardiothoracic surgery (3 TAPVC, 2 d-TGA, 2 VSD + IAA,1 TRUNCUS + TAPVC, 1 VSD + COA, 1 GLENN), who did not respond to conservative management, underwent treatment with PRP-FG. Follow-up was done for a period of 1-4 years. The age and diagnoses of pneumothorax after surgery were 85.5 ± 36.0 days and 62.4 ± 34.3 h, respectively. Persistent pneumothorax of 8 patients (80%) was cured completely after PRP-FG injection. PRP-FG therapy was failed in two patients who died. All cured patients had a normal life without any complications during follow-up. After PRP-FG injection, 3 patients stopped bubbling at one-time injection, 3 patients stopped bubbling at two-time injection, and 2 patients stopped bubbling at three-time injection. Two patients died during treatment; in these cases, one-time injections were done which was not successful. Persistent pneumothorax after congenital-cardiac surgery can be treated successfully with PRP-FG. This bedside minimal-invasive procedure may significantly decrease the morbidity and mortality rate. Further research is needed to confirm the efficacy of this promising treatment through multicentre clinical trials.

Effect of platelet rich plasma injection on bone formation in the expanded mid-palatal suture in rabbits: a randomized controlled animal study

BACKGROUND

Mid-Palatal suture expansion needs long retention period due to delayed bone formation in the expanded suture. Platelet-rich plasma (PRP) is a concentrated source of growth factors which increase bone formation. The aim of this study was to evaluate the effect of PRP injection on bone formation in expanded mid palatal suture in rabbits.

METHODS

In this prospective randomized controlled animal study, Twenty male rabbits (8-weeks-old) were subjected to mid-palatal expansion for 5 days. Animals were afterwards randomly divided into control group A & study group B. PRP was prepared and injected in the mid-palatal suture in animals belonging to group B only. After 6 weeks of retention, all animals were euthanized, and premaxillae were prepared for histological, histomorphometric and immunohistochemical analysis. Student t-test and paired t-test were used to compare the means of the two groups and within the same group respectively. Significance level set at p ≤ 0.05.

RESULTS

Histomorphometric analysis revealed a significant increase (p < 0.001) in the mean percentage of new bone in the study group (14.4%) compared to the control (1.4%). Suture width in study group was significantly wider than the control group (278.8 ± 9μms and 120.4 ± 3.4μms, p < 0.001). There was a significant increase in vascular density in study group than control group (309 ± 65.34 and 243.86 ± 48.1, p = 0.021). Osteopontin immuno-expression revealed a significant increase in optical density in study group than control group (0.21 ± 0.02 & 0.12 ± 0.01, p < 0.001).

CONCLUSIONS

In rabbit model, PRP injection can accelerate new bone formation in the expanded mid-palatal suture when compared to the control. This could hopefully result in a more stable midpalatal expansion and a reduced retention period.

The Role of Platelet-Rich Plasma Therapy in Joint Arthroplasty A Mini-Review

Orthobiologics are playing an increasingly large role in the clinical setting across multiple fields of surgery. Particularly, in the field of orthopedic surgery, the employment of platelet-rich plasma (PRP) therapy in total joint arthroscopy (TJA) has become popular for its prompted benefits of controlling pain, blood loss, and increased wound healing. PRP was originally used for thrombolytic conditions, however, the aforementioned potential benefits have led to its increased use across various fields of medicine including dermatology, neurosurgery, orthopedics, and sports medicine. Currently, there is a persisting gap in the literature surrounding the mechanism of action of PRP, as well as its true role in increasing positive patient outcomes in the context of TJA. Thus, this review aims to briefly highlight the physiological mechanisms underlining PRP therapy, evaluate recent preclinical and clinical data about its effects on TJA patient outcomes, and to describe its concomitant use in novel orthopedic-applications.

Effects of Conditioned Medium of Adipose-Derived Stem Cells Exposed to Platelet-Rich Plasma on the Expression of Endothelial Nitric Oxide Synthase and Angiogenesis by Endothelial Cells

ABSTRACT

Platelet-rich plasma (PRP) and adipose-derived stem cells (ADSCs) are known to secrete angiogenic factors that contribute to the treatment of intractable ulcers. The combination of PRP and ADSCs may enhance their angiogenic effects. However, it remains unclear whether treatment of ADSCs with PRP influences angiogenesis. We studied whether the conditioned medium from PRP-treated ADSCs under hypoxic conditions exerts angiogenic effects. Although PRP stimulated the proliferation of ADSCs obtained from rats, it decreased the mRNA levels of vascular endothelial growth factor, hepatocyte growth factor, and TGF-β1, but not of basic fibroblast growth factor, under hypoxia. The conditioned medium of PRP-treated ADSCs inhibited endothelial nitric oxide synthase phosphorylation, decreased NO production, and suppressed tube formation in human umbilical vein endothelial cells. Transplantation of ADSCs alone increased both blood flow and capillary density of the ischemic limb; however, its combination with PRP did not further improve blood flow or capillary density. This suggests that both conditioned medium of ADSCs treated with PRP and combination of PRP with ADSCs transplantation may attenuate the phosphorylation of endothelial nitric oxide synthase and angiogenesis.

Improved intervertebral bone union in ALIF rat model with porous hydroxyapatite/collagen combined with platelet-rich plasma

BACKGROUND CONTEXT

Platelet-rich plasma (PRP) can accelerate bone union in spinal fusion surgery with an autogenous bone graft. However, it is unclear whether bone union can be obtained by using artificial bone and PRP together in spinal interbody fusion surgery.

PURPOSE

This study aimed to determine whether interbody fusion can be achieved by transplanting porous hydroxyapatite/collagen(HAp/Col) which is an artificial bone material frequently used in spinal fusion surgery, together with PRP in the intervertebral disc space in rats.

STUDY DESIGN AND SETTING

A controlled laboratory study.

METHODS

A total of fourty 10-week old Sprague-Dawley rats were used in this study and assigned to three groups as follow: disc curettage only (control group, n=10), disc curettage + HAp/Col transplant (H group, n=10), and disc curettage + HAp/Col + PRP transplant (H+P group, n=10). The other 10 rats were sacrificed as blood donors for acquisition of PRP. Microcomputed tomography (μCT) examinations were performed to evaluate bone union, bone volume (BV), and bone mineral density (BMD) at 4, 8, and 12 weeks following surgery. Twelve weeks postoperatively, each group of three of L4-L5 spines was harvested to perform histological examination (hematoxylin & eosin stain) and the others were subjected to biomechanical testing (compression properties).

RESULTS

The platelet count in PRP was approximately 4.1 times greater than that in whole blood (260.6±26.2 × 10⁴ mg/dL and 64.3±2.9 × 10⁴ mg/dL in PRP and whole blood, respectively). All the L4-L5 lumbar discs were fused in the H+P group, whereas only one case was fused in the H group and none in the control group at 12 weeks after surgery. BV was significantly higher in the H+P group than in the H group or control groups (both p<.01), although BMD was not significantly different among the three groups. Upon histological analysis, mature bone formation was observed at the transplanted space in all cases in the H+P group, whereas fibrous tissue was observed at the location in the H and control groups. Regarding biomechanical properties, the ultimate load to failure was significantly higher in the H+P group than in the H group or control group (p=.021 and .013, respectively), although stiffness was not significantly different between the three groups.

CONCLUSION

The combination of porous HAp/Col and PRP at an appropriate concentration can promote bone union in the intervertebral disc space without using an autologous bone graft in the rat model. Bone tissue formation was histologically confirmed, and it was mechanically strong.

CLINICAL SIGNIFICANCE

This preclinical study showed that porous HAp/Col, when combined with PRP at an appropriate concentration, can induce bone union without autologous bone grafts. The results may eliminate the need for autologous bone collection for spinal fusion surgery in the future.

Advances in the Clinical Application of Platelet-Rich Plasma in the Foot and Ankle: A Review

Autologous and recombinant biologic substances have been generated as a result of the research into the cellular features of the healing process. Orthobiologics are increasingly being used in sports medicine and musculoskeletal surgery. Nevertheless, clinical data are limited; consequently, further studies are required, particularly in foot and ankle pathologies. This review aims to provide evidence of the most recent literature results and ignite the interest of orthopedic specialists eager for an update about the most current discussion on platelet-rich plasma (PRP) clinical applications in the foot and ankle fields. Previous studies have shown that platelet-rich plasma can be beneficial in treating various conditions, such as chronic foot ulcers, osteoarthritis, Achilles tendinopathy, etc. Despite the positive effects of PRP on various musculoskeletal conditions, more prospective studies are needed to confirm its effectiveness at treating ankle and foot pathologies. In addition to clinical trials, other factors, such as the quality of the research and the procedures involved, must be considered before they can be used in patients. More long-term evaluations are needed to support or oppose its application in treating foot and ankle disorders. We present the most extensive review of PRP's clinical applications in the foot and ankle field.

Single intraovarian dose of stem cell- and platelet-secreted factors mitigates age-related ovarian infertility in a murine model

BACKGROUND

Systemic administration of soluble factors from bone marrow-derived stem cells combined with activated platelet-rich plasma (SC-PRP) restored ovarian function, mediated through paracrine signaling, in murine models of chemotherapy-induced ovarian damage and human tissue from poor responder patients. However, the effects against age-related infertility and the efficacy of local administration have not been evaluated yet.

OBJECTIVE

This study aimed to assess whether a single intraovarian dose of stem cells combined with activated platelet-rich plasma can recover ovarian function, oocyte quality, and developmental competence in older mice.

STUDY DESIGN

The effects of stem cells combined with activated platelet-rich plasma against age-related infertility were assessed following controlled ovarian stimulation in an aging murine model reproducing 3 physiological stages of women's reproductive life, namely young, advanced maternal age, and menopausal (n=12 animals per group). Female mice were randomized to receive a single intraovarian injection (10 μL/ovary) of either saline, activated platelet-rich plasma, or stem cells combined with activated platelet-rich plasma. Seven days later, the mice were stimulated, naturally mated, and sacrificed to harvest their ovaries for histologic assessment and molecular analysis and their oviducts to evaluate oocyte maturation and to assess early embryo development.

RESULTS

A single intraovarian injection of stem cells combined with activated platelet-rich plasma promoted follicle activation and development in young, advanced maternal age, and old mice. Furthermore, stem cells combined with activated platelet-rich plasma rescued fertility in older mice by enhancing the quantity and quality of ovulated mature oocytes and supporting early embryo development to the blastocyst stage in all the evaluated ages. These fertility outcomes were positively associated with mitochondrial quality, treatment-increased mitochondrial DNA copy numbers, and reduced oxidative damage and apoptosis. Finally, the effects observed by histologic analysis were supported at the proteomic level. Functional proteomic analyses revealed molecular mechanisms involved in oocyte maturation and quality, mitochondrial function, and recovery of the ovarian stroma.

CONCLUSION

Bone marrow-derived stem cells combined with activated platelet-rich plasma is a promising treatment with the potential to improve the reproductive outcomes of women with age-related infertility, exceeding the restorative effects of platelet-rich plasma alone. Although further research in human ovarian samples is still required, the autologous nature of stem cell factors collected by noninvasive mobilization, their combination with platelet-rich plasma, and the local administration route suggest that stem cells combined with activated platelet-rich plasma treatment could be a potentially effective and safe application for future clinical practice.

The role of Platelet-Rich Plasma (PRP) intraarticular injections in restoring articular cartilage of osteoarthritic knees. A systematic review and meta-analysis

Objective

To assess the effect of PRP on knee articular cartilage content (thickness/volume) and examine the correlation between cartilage changes and clinical outcomes in patients with knee OA.

Method

A systematic literature search was performed using the Cochrane methodology in four online databases. Studies were included if they reported on cartilage content with cross-sectional imaging pre- and post-injection. A random-effects model meta-analysis was performed. Correlation with clinical outcomes was evaluated.

Results

14 studies (n ​= ​1099 patients) from 1452 records met the inclusion criteria: seven RCTs (n ​= ​688), one prospective (n ​= ​50), one retrospective (n ​= ​68), and four case-series (n ​= ​224). The PRP preparation process and treatment protocol varied widely (follow-up 6-12 months). In meta-analysis, PRP treatment was not associated with a significant increase in cartilage thickness (4 studies, n ​= ​187, standardized mean difference: Hedges g: 0.079; 95%CI: 0.358 - 0.516; p ​= ​0.723). Meta-analysis of 3 RCTs (n ​= ​112) showed no significant difference in the change of overall knee cartilage content with PRP injections compared with no PRP (Hedges' g: 0.217; 95%CI: 0.177 - 0.611; P ​= ​0.281).

Conclusion

The current literature does not support the PRP as chondrogenic in treatment of knee OA. However, there is substantial heterogeneity in the evaluated studies which limits the robustness of any conclusion. An adequately powered RCT, with a standardized PRP regime and standardized high-resolution MRI is needed to definitely define any effect of PRP on knee cartilage content and its relation to clinical outcomes. Until such high-quality evidence becomes available, we recommend that PRP is not administered with the intention of promoting chondrogenesis.

Comparative evaluation of demineralized freeze-dried bone allograft with and without concentrated growth factor membrane in the treatment of periodontal intrabony defects: a randomized controlled clinical trial

BACKGROUND

The current study's aim was to evaluate and compare demineralized freeze-dried bone allograft (DFDBA) with and without concentrated growth factor (CGF) membrane in the treatment of periodontal intrabony defects on both a clinical and radiographic level.

METHODS

30 stage III grade B periodontitis patients with bilateral intrabony defects were involved in the split mouth randomized controlled trial, and they received either DFDBA alone (control group) or DFDBA plus CGF membrane treatment (test group). At baseline and 6 and 12 months, the gingival index (GI), plaque index (PI), probing pocket depth (PPD), clinical attachment level (CAL), and gingival recession (GR) were assessed, whereas cone beam computed tomography was used to assess the bone defect height (BDH), vertical bone loss (VBL), bone defect depth (BDD), mesio-distal bone defect width (MDBDW), bucco-lingual bone defect width (BLBDW), and bone defect volume (CBCT) at baseline and 12 months.

RESULTS

The radiographic measures BDH, BDD, MDBDW, BLBDW, and BDV in the test group likewise showed a higher reduction in PPD and gain in CAL than the control group. The results of the intergroup comparison showed that the test group had statistically significant differences in BDH, BDD, and MDBDW.

CONCLUSION

The data show that the test group achieved better results, with greater reductions in PPD, gains in CAL, and decreases in BDH, BDD, MDBDW, BLBDW, and BDV.

CLINICAL RELEVANCE

The use of concentrated growth factor in conjunction with demineralized freeze-dried bone allograft may be suggested for the treatment of periodontal intrabony defects.

Albumin as a Biomaterial and Therapeutic Agent in Regenerative Medicine

Albumin is a constitutional plasma protein, with well-known biological functions, e.g., a nutrient for stem cells in culture. However, albumin is underutilized as a biomaterial in regenerative medicine. This review summarizes the advanced therapeutic uses of albumin, focusing on novel compositions that take advantage of the excellent regenerative potential of this protein. Albumin coating can be used for enhancing the biocompatibility of various types of implants, such as bone grafts or sutures. Albumin is mainly known as an anti-attachment protein; however, using it on implantable surfaces is just the opposite: it enhances stem cell adhesion and proliferation. The anticoagulant, antimicrobial and anti-inflammatory properties of albumin allow fine-tuning of the biological reaction to implantable tissue-engineering constructs. Another potential use is combining albumin with natural or synthetic materials that results in novel composites suitable for cardiac, neural, hard and soft tissue engineering. Recent advances in materials have made it possible to electrospin the globular albumin protein, opening up new possibilities for albumin-based scaffolds for cell therapy. Several described technologies have already entered the clinical phase, making good use of the excellent biological, but also regulatory, manufacturing and clinical features of serum albumin.

A comparative profile of total protein and six angiogenically-active growth factors in three platelet products

OBJECTIVES

Platelet-derived products have been shown as promising novel therapeutic agents for chronic wounds. However, their clinical use requires a greater degree of method standardisation, part of which involved more extensive cataloguing of their biochemical composition. This study aimed to quantify and compare total protein and 6 angiogenically-active growth factors in three distinct platelet products.

METHODS

Platelet Lysate (PL, n=5), Calcium-activated Platelet Rich Plasma (Ca-PRP, n=5) and Platelet-Rich Fibrin (PRF, n=5) were prepared from pooled platelet apheresis products (n=10). Ca-PRP and PRF were prepared from the same units (n=5) by activation with 20 mmolL^-1 calcium chloride. PL was prepared from the remaining (n=5) units using an established lysate. Total protein was quantified with the Bradford Assay. Sandwich enzyme-linked immunosorbent assay was used to quantify six growth factors: epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), stromal cell derived growth factor-1α (SDF-1α), endostatin, and transforming growth factor-β1 (TGF-β1).

RESULTS

Protein retrieval differed significantly (p<0.05) between the three products: PL (11.35±0.80 mg/mL) < Ca-PRP (20.44±8.17 mg/mL) < PRF (40.67±3.13 mg/mL). Growth factor yield was considerable in all three products and differed significantly for: VEGF (PL<PRF); EGF (Ca-PRP<PRF); HFG (PL<Ca-PRP); Endostatin (PL<Ca-PRP, PRF<Ca-PRP, PL<PRF) and TGF-β1 (Ca-PRP<PL, Ca-PRP<PRF).

CONCLUSIONS

Platelet apheresis products contain a substantial quantity of the investigated pro- and anti-angiogenic growth factors. Their release varies depending on the manufacturing protocol used. Clinically, alternate products could thus be combined to provide a therapeutically optimal mix of growth factors.

A systematic review on the efficacy of different types of platelet-rich plasma in the management of lateral epicondylitis

BACKGROUND

Platelet-rich plasma (PRP) is reported as an effective treatment for lateral epicondylitis (LE). Theoretically, different types of PRP have different therapeutic effects. However, there is controversy on the effects of different types of PRP in the treatment of LE. The purpose of this study was to systematically compare pain relief, functional improvement, and the success rate of treatment using 2 different types of PRP by reviewing and summarizing the data available in the current literature on LE after PRP injection.

METHODS

The PubMed, MEDLINE, Embase, Cochrane Library, and Web of Science databases were reviewed. A computerized literature search was performed for related studies published from database inception to August 2021 using the following terms: lateral epicondylitis, tennis elbow, tendinopathy, lateral elbow pain, PRP, and platelet-rich plasma. The PRP patients included in our study were divided into those receiving leukocyte-poor PRP (LP-PRP) and those receiving leukocyte-rich PRP (LR-PRP) according to the different preparation methods. Outcomes of interest included patient characteristics, types and preparations of PRP, clinical outcomes, success rates, and the safety of treatment at short- and long-term follow-up.

RESULTS

A total of 33 studies were evaluated in our analysis, including 2420 LE patients. LP-PRP was used in 19 of these studies, LR-PRP was used in 13, and both LP-PRP and LR-PRP were used in 1. Patients in both PRP groups showed significantly improved clinical outcomes after treatment compared with before treatment. The mean visual analog scale scores ranged from 6.1 to 8.0 before treatment, ranged from 1.5 to 4.0 at short-term follow-up, and ranged from 0.6 to 3.3 at long-term follow-up in the LR-PRP group. The mean visual analog scale scores ranged from 4.2 to 8.4 before treatment, 1.6 to 5.9 at short-term follow-up, and 0.7 to 2.7 at long-term follow-up in the LP-PRP group. The Disabilities of the Arm, Shoulder and Hand scores in the LR-PRP and LP-PRP groups ranged from 47.0 to 54.3 and 30.0 to 67.7, respectively, before treatment and ranged from 20.0 to 22.0 and 5.5 to 19.0, respectively, at long-term follow-up. The success rates in the LR-PRP and LP-PRP groups ranged from 70% to 100% and 36% to 100%, respectively. The complication rate was lower in the LP-PRP group (3.9%) than in the LR-PRP group (6.4%, P = .029), with the main complication being temporary pain after PRP treatment.

CONCLUSION

PRP treatment demonstrated significant improvements in terms of pain relief and functional improvement in LE patients regardless of the type of PRP. There were no significant differences in pain relief and functional improvement between LR-PRP and LP-PRP. The main complication was temporary pain after PRP injection, and the complication rate in the LP-PRP group was lower than that in the LR-PRP group.

Adipose tissue as a source of growth factors to promote wound healing: a human study of skin graft donor sites

Objective:

In the microenvironment of wound sites, naturally occurring growth factors are crucial for cell migration, opsonisation, chemotaxis, differentiation and angiogenesis. Exogenous growth factors, such as platelet-rich plasma (PRP) and adipose tissue, also improve healing.

Method:

In the present within-subject study, we described the effects of PRP and adipose tissue extract (ATE) on skin graft donor site wound healing in patients requiring split-thickness skin grafts. Each patient, having at least two donor sites, received both control (no growth factor) and experimental (PRP or ATE) treatments. Wounds were evaluated on days 5, 7, 10, 15, 30 and 60. Digital photography and spectral images were used to analyse haemoglobin and melanin content, and re-epithelialisation area. Pain was assessed by visual analogue scale. Scar characteristics were scored on days 30 and 60. Biomaterial samples were analysed for growth factor and protein content.

Results:

The study included 24 patients (18 male and six female; mean age: 59.1 years). PRP was topically applied to wounds in 11 patients (13 donor sites) and ATE in 13 patients (15 sites). ATE-treated donor sites exhibited significantly accelerated wound re-epithelialisation on days 5 and 7 compared with control sites (p=0.003 and 0.04, respectively). PRP accelerated healing on day 7 compared with control sites (p=0.001). Additionally, the application of ATE improved scar quality on days 30 and 60 (p=0.0005 and 0.02, respectively). Pain scores did not differ significantly between treatments.

Conclusion:

In this study, both growth factor sources stimulated wound healing. ATE is an alternative source of growth factors that promote early wound healing and improve scar quality.

Use of platelet-rich plasma in irradiated patients to treat and prevent complications of head and neck surgery

Nowadays, many patients facing head and neck oncological surgery have a history of tissue irradiation. This represents an important risk factor for postsurgical complications, including dehiscences and fistulas. Platelet-rich plasma (PRP) obtained from the patient's blood represents an easy, fast and inexpensive method for the prevention and treatment of such complications. We present three cases of previously irradiated patients in which PRP was successfully used to prevent and treat postsurgical complications.

Dual-Function Semaphorin 4D Released by Platelets: Suppression of Osteoblastogenesis and Promotion of Osteoclastogenesis

Effects of the antiosteoblastogenesis factor Semaphorin 4D (Sema4D), expressed by thrombin-activated platelets (TPs), on osteoblastogenesis, as well as osteoclastogenesis, were investigated in vitro. Intact platelets released both Sema4D and IGF-1. However, in response to stimulation with thrombin, platelets upregulated the release of Sema4D, but not IGF-1. Anti-Sema4D-neutralizing monoclonal antibody (mAb) upregulated TP-mediated osteoblastogenesis in MC3T3-E1 osteoblast precursors. MC3T3-E1 cells exposed to TPs induced phosphorylation of Akt and ERK further upregulated by the addition of anti-sema4D-mAb, suggesting the suppressive effects of TP-expressing Sema4D on osteoblastogenesis. On the other hand, TPs promoted RANKL-mediated osteoclastogenesis in the primary culture of bone-marrow-derived mononuclear cells (BMMCs). Among the known three receptors of Sema4D, including Plexin B1, Plexin B2 and CD72, little Plexin B2 was detected, and no Plexin B1 was detected, but a high level of CD72 mRNA was detected in RANKL-stimulated BMMCs by qPCR. Both anti-Sema4D-mAb and anti-CD72-mAb suppressed RANKL-induced osteoclast formation and bone resorptive activity, suggesting that Sema4D released by TPs promotes osteoclastogenesis via ligation to a CD72 receptor. This study demonstrated that Sema4D released by TPs suppresses osteogenic activity and promotes osteoclastogenesis, suggesting the novel property of platelets in bone-remodeling processes.

Effect of Microgravity on Endothelial Cell Function, Angiogenesis, and Vessel Remodeling During Wound Healing

Wound healing is a complex phenomenon that involves different cell types with various functions, i.e., keratinocytes, fibroblasts, and endothelial cells, all influenced by the action of soluble mediators and rearrangement of the extracellular matrix (ECM). Physiological angiogenesis occurs in the granulation tissue during wound healing to allow oxygen and nutrient supply and waste product removal. Angiogenesis output comes from a balance between pro- and antiangiogenic factors, which is finely regulated in a spatial and time-dependent manner, in order to avoid insufficient or excessive nonreparative neovascularization. The understanding of the factors and mechanisms that control angiogenesis and their change following unloading conditions (in a real or simulated space environment) will allow to optimize the tissue response in case of traumatic injury or medical intervention. The potential countermeasures under development to optimize the reparative angiogenesis that contributes to tissue healing on Earth will be discussed in relation to their exploitability in space.

The Combined Use of Platelet-Rich Plasma and Adipose-Derived Mesenchymal Stem Cells Promotes Healing. A Review of Experimental Models and Future Perspectives

Wound healing and tissue regeneration are a field of clinical medicine presenting high research interest, since various local and systematic factors can inhibit these processes and lead to an inferior result. New methods of healing enhancement constantly arise, which, however, require experimental validation before their establishment in everyday practice. Platelet-rich plasma (PRP) is a well-known autologous factor that promotes tissue healing in various surgical defects. PRP derives from the centrifugation of peripheral blood and has a high concentration of growth factors that promote healing. Recently, the use of adipose-derived mesenchymal stem cells (ADMSCs) has been thoroughly investigated as a form of wound healing enhancement. ADMSCs are autologous stem cells deriving from fat tissue, with a capability of differentiation in specific cells, depending on the micro-environment that they are exposed to. The aim of the present comprehensive review is to record the experimental studies that have been published and investigate the synergistic use of PRP and ADMSC in animal models. The technical aspects of experimentations, as well as the major results of each study, are discussed. In addition, the limited clinical studies including humans are also reported. Future perspectives are discussed, along with the limitations of current studies on the long-term follow up needed on efficacy and safety.

PRP and PRF-Subgroups and Divisions When Used in Dentistry

Blood derivates, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), are autogenous sources of many growth factors that are involved in the healing and regeneration of tissues, and for this reason, are used in dentistry treatments. This fact also contributes to the growing interest in these biomaterials in regenerative personalized medicine. The multitude of platelet-rich forms creates many possibilities for their use. This semi-systematic review describes and compares the methods of obtaining properties and potential uses of these materials in personalized treatments.

Pro- and Anti-Angiogenic Factors: Their Relevance in Diabetic Foot Syndrome-A Review

Peripheral arterial disease can involve tissue loss in up to 50% of patients with diabetic foot syndrome (DFS). Consequently, revascularization of narrowed or occluded arteries is one of the most common forms of comprehensive treatment. However, technically successful angioplasty does not always result in the healing of ulcers. The pathomechanism of this phenomenon is still not fully understood, but inadequate angiogenesis in tissue repair may play an essential role. Changes in pro- and anti-angiogenic factors among patients with DFS are not always clear and conclusive. In particular, some studies underline the role of decreased concentration of pro-angiogenic factors and higher levels of anti-angiogenic mediators. Nevertheless, there are still controversial issues, including the paradox of impaired wound healing despite high concentrations of some pro-angiogenic factors, dynamics of their expression during the healing process, and their mutual relationships. Exploring this process among diabetic patients may provide new insight into well-known methods of treatment and show their real benefits and chances for improving outcomes.

Improved Posterolateral Lumbar Spinal Fusion Using a Biomimetic, Nanocomposite Scaffold Augmented by Autologous Platelet-Rich Plasma

Remodeling of the human bony skeleton is constantly occurring with up to 10% annual bone volume turnover from osteoclastic and osteoblastic activity. A shift toward resorption can result in osteoporosis and pathologic fractures, while a shift toward deposition is required after traumatic, or surgical injury. Spinal fusion represents one such state, requiring a substantial regenerative response to immobilize adjacent vertebrae through bony union. Autologous bone grafts were used extensively prior to the advent of advanced therapeutics incorporating exogenous growth factors and biomaterials. Besides cost constraints, these applications have demonstrated patient safety concerns. This study evaluated the regenerative ability of a nanostructured, magnesium-doped, hydroxyapatite/type I collagen scaffold (MHA/Coll) augmented by autologous platelet-rich plasma (PRP) in an orthotopic model of posterolateral lumbar spinal fusion. After bilateral decortication, rabbits received either the scaffold alone (Group 1) or scaffold with PRP (Group 2) to the anatomic right side. Bone regeneration and fusion success compared to internal control were assessed by DynaCT with 3-D reconstruction at 2, 4, and 6 weeks postoperatively followed by comparative osteogenic gene expression and representative histopathology. Both groups formed significantly more new bone volume than control, and Group 2 subjects produced significantly more trabecular and cortical bone than Group 1 subjects. Successful fusion was seen in one Group 1 animal (12.5%) and 6/8 Group 2 animals (75%). This enhanced effect by autologous PRP treatment appears to occur via astounding upregulation of key osteogenic genes. Both groups demonstrated significant gene upregulation compared to vertebral bone controls for all genes. Group 1 averaged 2.21-fold upregulation of RUNX2 gene, 3.20-fold upregulation of SPARC gene, and 3.67-fold upregulation of SPP1 gene. Depending on anatomical subgroup (cranial, mid, caudal scaffold portions), Group 2 had significantly higher average expression of all genes than both control and Group 1–RUNX2 (8.23–19.74 fold), SPARC (18.67–55.44 fold), and SPP1 (46.09–90.65 fold). Our data collectively demonstrate the osteoinductive nature of a nanostructured MHA/Coll scaffold, a beneficial effect of augmentation with autologous PRP, and an ability to achieve clinical fusion when applied together in an orthotopic model. This has implications both for future study and biomedical innovation of bone-forming therapeutics.

Strategies for managing asherman's syndrome and endometrial atrophy: Since the classical experimental models to the new bioengineering approach

Endometrial function is essential for embryo implantation and pregnancy, but managing endometrial thickness that is too thin to support pregnancy or an endometrium of compromised functionality due to intrauterine adhesions is an ongoing challenge in reproductive medicine. Here, we review current and emerging therapeutic and experimental options for endometrial regeneration with a focus on animal models used to study solutions for Asherman's syndrome and endometrial atrophy, which both involve a damaged endometrium. A review of existing literature was performed that confirmed the lack of consensus on endometrial therapeutic options, though promising new alternatives have emerged in recent years (platelet-rich plasma, exosomes derived from stem cells, bioengineering-based techniques, endometrial organoids, among others). In the future, basic research using established experimental models of endometrial pathologies (combined with new high-tech solutions) and human clinical trials with large population sizes are needed to evaluate these emerging and new endometrial therapies.

Cord blood and amniotic membrane extract eye drop preparations display immune-suppressive and regenerative properties

Diseases and injuries that compromise the ocular surface cause considerable patient distress and have long term consequences for their quality of life. Treatment modalities that can address the delicate balance of tissue regeneration, inflammation and maintenance of corneal transparency are therefore needed. We have recently formulated two novel eye drops from placental tissues: cord blood platelet lysate (CBED) and amniotic membrane extract eye drops (AMED), which can be used to treat severe ocular disorders. Here we characterise these two preparations by measuring: (a) growth factors (GF) and cytokines composition, (b) promotion of human corneal epithelial cell (HCEC) growth and (c) effects on immune cells in a lymphocyte culture assay. Finally, their bioavailability was assayed in an ex vivo porcine corneal model. We show that both preparations contain GF and cytokines that were able to promote the in vitro growth of HCEC and support repair in an in vitro scratch test. When assessed in a lymphocyte culture, both favoured immune suppression reducing the cellular expression of NKG2D and CD107a as well as the production of interferon gamma (IFN-γ) in natural killer, NKT and T cells. Regarding bioavailability, CBED active molecules were found mainly in the pre-corneal fraction with some penetration into the corneal fraction, in an ex vivo model. In summary, both placental-derived allogeneic preparations, CBED and AMED, display regenerative and immunomodulatory capabilities. These results will help define mechanisms of action and the best indications and doses of each product for use in a particular patient and support the development of off-the-shelf therapies for ocular surface pathologies in which wound healing defects and inflammatory events are contributing factors.

Stem cell-secreted factor therapy regenerates the ovarian niche and rescues follicles

BACKGROUND

Ovarian senescence is a normal age-associated phenomenon, but increasingly younger women are affected by diminished ovarian reserves or premature ovarian insufficiency. There is an urgent need for developing therapies to improve ovarian function in these patients. In this context, previous studies suggest that stem cell-secreted factors could have regenerative properties in the ovaries.

OBJECTIVE

This study aimed to test the ability of various human plasma sources, enriched in stem cell-secreted factors, and the mechanisms behind their regenerative properties, to repair ovarian damage and to promote follicular development.

STUDY DESIGN

In the first phase, the effects of human plasma enriched in bone marrow stem cell soluble factors by granulocyte colony-stimulating factor mobilization, umbilical cord blood plasma, and their activated forms on ovarian niche, follicle development, and breeding performance were assessed in mouse models of chemotherapy-induced ovarian damage (n=7 per group). In addition, the proteomic profile of each plasma was analyzed to find putative proteins and mechanism involved in their regenerative properties in ovarian tissue. In the second phase, the most effective plasma treatment was validated in human ovarian cortex xenografted in immunodeficient mice (n=4 per group).

RESULTS

Infusion of human plasma enriched bone marrow stem cell soluble factors by granulocyte colony-stimulating factor mobilization or of umbilical cord blood plasma-induced varying degrees of microvessel formation and cell proliferation and reduced apoptosis in ovarian tissue to rescue follicular development and fertility in mouse models of ovarian damage. Plasma activation enhanced these effects. Activated granulocyte colony-stimulating factor plasma was the most potent inducing ovarian rescue in both mice and human ovaries, and proteomic analysis indicated that its effects may be mediated by soluble factors related to cell cycle and apoptosis, gene expression, signal transduction, cell communication, response to stress, and DNA repair of double-strand breaks, the most common form of age-induced damage in oocytes.

CONCLUSION

Our findings suggested that stem cell-secreted factors present in both granulocyte colony-stimulating factor-mobilized and umbilical cord blood plasma could be an effective treatment for increasing the reproductive outcomes in women with impaired ovarian function owing to several causes. The activated granulocyte colony-stimulating factor plasma, which is already enriched in both stem cell-secreted factors and platelet-enclosed growth factors, seems to be the most promising treatment because of its most potent restorative effects on the ovary together with the autologous source.

The use of platelet-rich products for skin graft donor site healing: a systematic review and meta-analysis

Split thickness skin grafting is a common reconstructive technique which carries unavoidable donor site morbidity. The aim of this systematic review and meta-analysis is to present the evidence for the use of platelet rich plasma as an adjunct to donor site wound healing. A comprehensive literature search was performed, according to PRISMA guidelines from inception to August 2020, for studies regarding platelet rich plasma and skin graft donor site healing. Animal studies, case series of less than three cases and studies reporting histological outcomes only were excluded. The literature search identified 114 articles. After applying the exclusion criteria, four randomised control trials and two case-control studies remained, incorporating a total of 218 wounds in 139 patients. Four out of six studies reported total healing times for donor site wounds. Pooled analysis showed a significant reduction in healing time when donor wounds were treated with PRP versus controls [MD 5.95, 95% CI 5.04-6.85, p < 0.001]. Of the five studies which reported pain at dressing change, four showed significantly reduced pain scores for the platelet rich plasma treated wounds versus control. There were no significant complications recorded in the treated wounds. The current evidence basis for platelet rich plasma in donor site healing is limited by heterogeneous methodology and reporting outcomes and low powered studies. Nevertheless, the preponderance of data supports its use for accelerating wound healing and reducing pain at dressing change. These preliminary findings need to be substantiated with higher powered randomised controlled trials with standardised PRP manufacture and reporting structures.

Effect of platelet-rich plasma on fracture healing

Bone has the ability to completely regenerate under normal healing conditions. Although fractures generally heal uneventfully, healing problems such as delayed union or nonunion still occur in approximately 10% of patients. Optimal healing potential involves an interplay of biomechanical and biological factors. Orthopedic implants are commonly used for providing the necessary biomechanical support. In situations where the biological factors that are needed for fracture healing are deemed inadequate, additional biological enhancement is needed. With platelets being packed with granules that contain growth factors and other proteins that have osteoinductive capacity, local application of platelet concentrates, also called platelet-rich plasma (PRP) seems an attractive biological to enhance fracture healing. This review shows an overview of the use PRP and its effect in enhancing fracture healing. PRP is extracted from the patient's own blood, supporting that its use is considered safe. Although PRP showed effective in some studies, other studies showed controversial results. Conflicts in the literature may be explained by the absence of consensus about the preparation of PRP, differences in platelet counts, low number of patients, and absence of a standard application technique. More studies addressing these issues are needed in order to determine the true effect of PRP on fracture healing.

Foot and Ankle Injections in Athletes

CONTEXT

Injections are commonly used by health care practitioners to treat foot and ankle injuries in athletes despite ongoing questions regarding efficacy and safety.

EVIDENCE ACQUISITION

An extensive literature review was performed through MEDLINE, Google Scholar, and EBSCOhost from database inception to 2021. Keywords searched were injections, athletes, sports, foot and ankle, corticosteroids, platelet-rich plasma, and placental tissue. Search results included articles written in the English language and encompassed reviews, case series, empirical studies, and basic science articles.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Corticosteroids, platelet-rich plasma/autologous blood, anesthetic, and placental tissue injections are commonly used in the treatment of foot and ankle injuries. Primary indications for injections in athletes include plantar fasciitis, Achilles tendinosis, isolated syndesmotic injury, and ankle impingement with varying clinical results.

CONCLUSIONS

Despite promising results from limited case series and comparative studies, the data for safety and efficacy of injections for foot and ankle injuries in athletes remain inconclusive.

Platelet-rich plasma fibrin glue for treatment of chylothorax following cavopulmonary connections

OBJECTIVES

The postoperative persistence of chylothorax is a fatal complication of paediatric cardiac surgery. There is an urgent need for an effective treatment of chylothorax. This study reports the application of allogenic platelet-rich plasma fibrin glue (PRP-FG) as a conservative therapy before reoperation.

METHODS

Over a 9-year period, from 2010 to 2019, 27 patients with persistent chylothorax following a cavopulmonary connection, with a mean latency period of 11 days (range 10-15 days), were treated with PRP-FG. These patients were selected because they had not responded positively to initial conservative management plans. The patients were followed up for 9 years.

RESULTS

Twenty-five patients (92%) responded positively to treatment with PRP-FG; 2 patients did not respond to the treatment and died after reoperation. All of the successfully treated patients in follow-up continued to live a healthy life without further complications.

CONCLUSIONS

Recalcitrant chylothorax that persists after paediatric cardiac surgery responded positively to treatment with PRP-FG. This technique precluded the need for another operation and significantly decreased the morbidity and mortality rates.

Evidence-Based Clinical Efficacy of Leukocyte and Platelet-Rich Fibrin in Maxillary Sinus Floor Lift, Graft and Surgical Augmentation Procedures

Bone augmentation techniques have increasingly been indicated for re-creating adequate bone height and volume suitable for dental implant sites. This is particularly applicable in the severely atrophic posterior maxilla where sinus perforation (ruptured Schneiderian membrane) is a very common complication and sinus floor elevation or lift is frequently considered a standard procedure. The augmentation of the maxillary sinus can be performed with or without grafting biomaterials. Herein, numerous biomaterials and bone substitutes have been proposed, primarily to sustain the lifted space. In addition, cytokines and growth factors have been used to stimulate angiogenesis, enhance bone formation as well as improve healing and recovery period, either as the sole filling material or in combination with bone substitute materials. Within such, is the family of autologous blood extracts, so-called platelet concentrates, which are simply the "product" resulting from the simple centrifugation of collected whole blood samples of the patient, immediately pre-surgery. Platelet-Rich Fibrin (PRF), a sub-family of platelet concentrates, is a three-dimensional (3-D) autogenous biomaterial obtained, without including anti-coagulants, bovine thrombin, additives, or any gelifying agents during the centrifugation process. Today, it is safe to say that, in implant dentistry and oral and maxillofacial surgery, PRFs (particularly, the pure platelet-rich fibrin or P-PRF and leukocyte and platelet-rich fibrin or L-PRF sub-classes) are receiving the most attention, essentially due to their simplicity, rapidness, user-friendliness/malleability, and cost-effectiveness. Whether used as the sole "bioactive" filling/additive material or combined with bone substitutes, the revolutionary second-generation PRFs have been very often associated with promising clinical results. Hence, this review aims to provide a 10-years update on the clinical effectiveness of L-PRF when applied/used as the "sole" biomaterial in maxillary sinus augmentation procedures. An electronic search using specific keywords for L-PRF and maxillary sinus augmentation was conducted in three main databases (PubMed-MEDLINE database, Google Scholar and Cochrane library) for the period between January 2009-February 2020. The quest yielded a total of 468 articles. Based on the pre-established strict inclusion/exclusion criteria, only seven articles were deemed eligible and included in the analysis. Surprisingly, of the 5 studies which used de-proteinized bovine bone mineral (DBBM) in combination with L-PRF, 60% acclaimed no significant effects and only 40% declared positive effects. Of the two articles which had used allogenous bone graft, 50% declared no significant effects and 50% acclaimed positive effects. Only one study had used L-PRF as the sole grafting material and reported a positive effect. Likewise, positive effects were reported in one other study using L-PRF in combination with a collagen membrane. Due to the heterogeneity of the included studies, this review is limited by the inability to perform a proper systematic meta-analysis. Overall, most of the published studies reported impressive results of L-PRF application as a grafting material (sole or adjuvant) in maxillary sinus augmentation and dental implant restorative procedures. Yet, distinct technical processing for L-PRF preparation was noted. Hence, studies should be approached with caution. Here in, in sinus lift and treatment of Schneider membrane, the formation of mature bone remains inconclusive. More studies are eagerly awaited in order to prove the beneficial or detrimental effects of PRFs, in general and L-PRFs, in specific; especially in their tissue regenerative potential pertaining to the promotion of angiogenesis, enhancing of cell proliferation, stimulation of cell migration and autocrine/paracrine secretion of growth factors, as well as to reach a consensus or a conclusive and distinct determination of the effect of leukocytes (and their inclusion) on inflammation or edema and pain; a call for standardization in PRFs and L-PRFs composition reporting and regimenting the preparation protocols.

Brucella abortus-Stimulated Platelets Activate Brain Microvascular Endothelial Cells Increasing Cell Transmigration through the Erk1/2 Pathway

Central nervous system invasion by bacteria of the genus Brucella results in an inflammatory disorder called neurobrucellosis. A common feature associated with this pathology is blood-brain barrier (BBB) activation. However, the underlying mechanisms involved with such BBB activation remain unknown. The aim of this work was to investigate the role of Brucella abortus-stimulated platelets on human brain microvascular endothelial cell (HBMEC) activation. Platelets enhanced HBMEC activation in response to B. abortus infection. Furthermore, supernatants from B. abortus-stimulated platelets also activated brain endothelial cells, inducing increased secretion of IL-6, IL-8, CCL-2 as well as ICAM-1 and CD40 upregulation on HBMEC compared with supernatants from unstimulated platelets. Outer membrane protein 19, a B. abortus lipoprotein, recapitulated B. abortus-mediated activation of HBMECs by platelets. In addition, supernatants from B. abortus-activated platelets promoted transendothelial migration of neutrophils and monocytes. Finally, using a pharmacological inhibitor, we demonstrated that the Erk1/2 pathway is involved in the endothelial activation induced by B. abortus-stimulated platelets and also in transendothelial migration of neutrophils. These results describe a mechanism whereby B. abortus-stimulated platelets induce endothelial cell activation, promoting neutrophils and monocytes to traverse the BBB probably contributing to the inflammatory pathology of neurobrucellosis.

Autologous platelet-rich plasma in the treatment of refractory corneal ulcers: A case report

Purpose

To evaluate the efficacy of a low-cost preparation of platelet-rich plasma (PRP) eye drops in the treatment of persistent non-infectious corneal ulcer.

Observations

A 67-year-old female presented to our clinic with a wide corneal ulcer and severe paracentral corneal thinning refractory to medical therapy with antibiotics, lubricant and contact lens bandage. The patient received a novel preparation of PRP solution. After 15 days of therapy, we observed complete resolution of the corneal ulcer with regrowth of the epithelium and a reduction in corneal opacity.

Conclusion and importance

Although the low-cost PRP preparation gives a lower platelet concentration than standard procedures, our work shows this preparation to be effective in the treatment of refractory non-infectious corneal ulcer.

Cord Blood Platelet Rich Plasma Derivatives for Clinical Applications in Non-transfusion Medicine

Cord blood platelet rich plasma (CB-PRP) derivatives have been investigated as potential therapeutic agents for the treatment of diverse conditions including ocular surface disease and skin ulcers. We have developed processes for the formulation of several CB-PRP preparations, which have different composition and attributes. Here we describe the molecular characteristics of these preparations and we make recommendations as to their most appropriate clinical application based on functional and immunomodulatory profiles. We show that incubation of adult peripheral blood mononuclear cells (PBMCs) with all three preparations dramatically reduced the production of INFγ and the expression of NKG2D and CD107a in NK, NKT, and T cells thus diminishing their activation, we propose that the likely mechanism is the high levels of soluble NKG2D ligands present in plasma. Of the three preparations we investigated, CB platelet lysate (PL) and platelet releaseate (PR) have higher concentrations of trophic and pro-angiogenic factors, CB platelet poor plasma (PPP) has the lowest concentration of all analytes measured. Based on these finding we propose that CB-PR is the most suitable raw material for skin wound patches, while CB-PL and PPP can be used to prepare eye drops for severe ocular surface pathologies and inflammatory conditions such as corneal ulcers or severe dry eye disease, respectively.

Comparison of Platelet-Rich Plasma-Impregnated Suture Material with Low and High Platelet Concentration to Improve Colonic Anastomotic Wound Healing in Rats

Objective

This study was designed to investigate the impact of using suture material impregnated with platelet-rich plasma (PRP) in different platelet concentrations on colonic anastomotic wound healing in rats.

Methods

A total of 24 Sprague Dawley female rats were separated into 3 groups (n = 8 for each) including the control group (CON; standard vicryl suture repair), the low platelet concentrate PRP group (L-PRP; suture material impregnated with PRP containing average 2.7-fold (range, 2.0 to 3.1) higher amount of platelets vs. control), and the high platelet concentrate PRP group (H-PRP; suture material impregnated with PRP containing average 5.1-fold (range, 4.8 to 5.4) higher amount of platelets vs. control). Rats were sacrificed on the postoperative 7^th day for analysis of colonic anastomosis region including macroscopic observation, measurement of anastomotic bursting pressure (ABP), and the hydroxyproline levels and histopathological findings in colon tissue samples.

Results

Total injury scores were significantly lower in the L-PRP and H-PRP groups than those in the control group (median (range) 13.00 (7.00) and 11.50 (6.00) vs. 15.50 (4.00), p < 0.05 and p < 0.01, respectively). ABP values (180.00 (49.00) vs. 124.00 (62.00) and 121.00 (57.00) mmHg, p < 0.001 for each) and tissue hydroxyproline levels (0.56 (0.37) vs. 0.25 (0.17) and 0.39 (0.10) μg/mg tissue, p < 0.001 and p < 0.05, respectively) were significantly higher in the L-PRP group as compared with those in the control and H-PRP groups.

Conclusion

In conclusion, our findings revealed PRP application to colonic anastomosis sutures to promote the anastomotic healing process. The platelet concentration of PRP seems to have a significant impact on the outcome with superior efficacy of L-PRP over H-PRP in terms of bursting pressures and collagen concentration at the anastomotic site.

Cord blood-derived platelet concentrates as starting material for new therapeutic blood components prepared in a public cord blood bank: from product development to clinical application

BACKGROUND

There are many advantages to using cord blood (CB) as a source of therapeutic platelet and plasma derivatives for regenerative medicine. These include availability, universal use, young donor source, and virally safe biological material, rich in tissue regenerative factors.

MATERIALS AND METHODS

We aimed to validate a bioprocess design for the production of cord blood-derived platelet concentrates (CBPC) in a public Cord Blood Bank (CBB). CBPC was defined as a product of 10±5 mL, 1,000±200×10⁹/L total platelets, free of erythrocytes and leukocytes. A total of 300 CB units were centrifuged in two steps to enrich for platelets, in compliance with Good Manufacturing Practice. The samples were tested for the degree of platelet activation present, and the levels of growth factor were analysed to evaluate their potential function. CBPC were then activated after thawing with 10% calcium gluconate to generate platelet gels (CBPG) to treat patients with diabetic foot ulcers.

RESULTS

After processing, 84% of the products fulfilled the acceptance criteria. Final products contained 1,017±149×10⁶ platelets/mL in 10±3mL of plasma. Platelet recovery was 50±9%. The methods described here ensure depletion of white and red blood cells down to a residual concentration of 0.2±0.1×10⁶/mL and 0.03±0.02×10⁶/mL, respectively. Platelets showed low levels of activation during processing, but were significantly activated after thawing, as indicated by an increase in CD62p expression. The growth factors EGF, VEGF, bFGF, PDGF AB/BB and TGF-β1 were at concentrations of 1,706±123 pg/mL; 1,602±227 pg/mL; 314±26 pg/mL; 30±1.5 ng/mL; 24±2 ng/mL (mean±standard error of mean), respectively. For clinical evaluation, a total of 21 CBPG were applied in 3 patients, with no reported adverse events and improvement of ulcers in all of them.

DISCUSSION

We designed and validated a highly reproducible, closed system method to manufacture high quality CBPC suitable for clinical applications using CB units not suitable for transplantation in a public CBB.

Effects of submucosal PRP injection on wound healing in endonasal surgeries: an experimental study

PURPOSE

To investigate the effects of submucosal platelet-rich plasma (PRP) injection on nasal mucosal wound healing after endoscopic sinus surgery.

METHODS

24 New Zealand white rabbits were randomly divided into three groups. To mimic surgery, injury was created using 3-mm punch forceps on ventral turbinate mucosa for all groups. Submucosal PRP was injected to the damaged mucosa in the first group (PRP group, n = 8), where 0.9% saline solution to the second group (saline group, n = 8) and no injection to the third one (control group, n = 8). All the animals were sacrificed 14 days after surgery; histopathological examination and hydroxyproline measurements were performed on the mucosa of all groups.

RESULTS

Neutrophils, goblet cells, and collagen intensity were found significantly lower (p < 0.05) in PRP group than the control group. Also, the number of ciliary and goblet cells, and collagen intensity were found significantly lower (p < 0.05) in PRP group, than the saline group. In PRP group, hydroxyproline levels were found (p < 0.05) significantly lower than the saline and the control group, and no significant difference was found between the saline group and the control group (p > 0.05).

CONCLUSION

There are many studies in literature showing the positive effects of PRP on wound healing. The results of this study also demonstrated positive effects of PRP on the nasal mucosa. According to these results, PRP injection to the injured nasal mucosa showed anti-inflammatory, mucus-softening, and synechia-reducing effects. Therefore, submucosal PRP injection after endonasal surgeries can be considered an effective application for maintaining nasal physiology.

Proteomic Classification and Identification of Proteins Related to Tissue Healing of Platelet-Rich Plasma

Background

Platelet-rich plasma (PRP) is a plasma component of autologous blood containing a high concentration of platelets. PRP is used to promote healing of damaged tissues. However, there are not many studies on the composition and expression patterns of active proteins in PRP. The purpose of this study was to identify unknown factors that contribute to tissue healing by proteomic analysis of proteins in PRP.

Methods

Three men in their 30s with no basal disease participated in this study. All identified proteins were classified for tissue healing-related functions on the basis of the gene ontology analysis of adhesion molecule with Ig-like domain 2 (AmiGO2). PRP was prepared by using the ACP kit and GPS III kit.

Results

We identified a total of 125 proteins related to wound healing, along with three proteins for angiogenesis involved in wound healing, two proteins for fibroblast migration, four proteins for collagen biosynthesis process, two proteins for glycosaminoglycan biosynthesis process, and 13 proteins for glycosaminoglycan binding. So, in addition to the growth factors that have been already known to be involved in tissue healing, 25 new proteins were identified.

Conclusions

We identified the unknown proteins associated with tissue healing in PRP. Our findings may serve as a foundation for the establishment of basic medical evidence for PRP applications.

Use of autologous platelet-rich plasma in healing skin graft donor sites

Objective:

To demonstrate that the use of platelet-rich plasma (PRP) enhances both the quality of healing and the time required for wound healing at a skin graft donor site.

Methods:

Patients who had dermo-epidermal skin grafts taken from the thigh area were included in a prospective, randomised clinical study. PRP was applied to one donor site and then covered with Vaseline-impregnated, open-weave gauze and gauze, while the contralateral donor site on the other thigh served as a control and was covered with the open-weave gauze and gauze without PRP.

Results:

A total of 24 patients took part in the study, of which three developed infections and were thus removed from the study. Use of PRP reduced the wound healing time of the dermo-epidermal graft donor sites by a mean 17.8% and median 18 days. On average, the treated donor sites healed in 14.9 days compared with 18.4 days for the control group. The median was 14 days compared with 18 days in the control group (p=0.026). In one patient, healing was slower on the side where PRP was applied. In 20 patients, healing of the donor site was accelerated where PRP was applied.

Conclusion:

The study demonstrated a beneficial effect of PRP, as healing time was shortened. Using PRP to heal wounds could be beneficial for patients for whom commonly available wound healing therapies have failed, as well as for high-risk patient groups for whom problematic wound healing may be expected.

Human periodontal ligament stem cells on calcium phosphate scaffold delivering platelet lysate to enhance bone regeneration

Human periodontal ligament stem cells (hPDLSCs) are promising for tissue engineering applications but have received relatively little attention. Human platelet lysate (HPL) contains a cocktail of growth factors. To date, there has been no report on hPDLSC seeding on scaffolds loaded with HPL. The objectives of this study were to develop a calcium phosphate cement (CPC)-chitosan scaffold loaded with HPL and investigate their effects on hPDLSC viability, osteogenic differentiation and bone mineral synthesis for the first time. hPDLSCs were harvested from extracted human teeth. Scaffolds were formed by mixing CPC powder with a chitosan solution containing HPL. Four groups were tested: CPC-chitosan + 0% HPL (control); CPC-chitosan + 2.66% HPL; CPC-chitosan + 5.31% HPL; CPC-chitosan + 10.63% HPL. Scanning electron microscopy, live/dead staining, CCK-8, qRT-PCR, alkaline phosphatase and bone minerals assay were applied for hPDLSCs on scaffolds. hPDLSCs attached well on CPC-chitosan scaffold. Adding 10.63% HPL into CPC increased cell proliferation and viability (p < 0.05). ALP gene expression of CPC-chitosan + 10.63% HPL was 7-fold that of 0% HPL at 14 days. Runx2, OSX and Coll1 of CPC-chitosan + 10.63% HPL was 2-3 folds those at 0% HPL (p < 0.05). ALP activity of CPC-chitosan + 10.63% HPL was 2-fold that at 0% HPL (p < 0.05). Bone minerals synthesized by hPDLSCs for CPC-chitosan + 10.63% HPL was 3-fold that at 0% HPL (p < 0.05). This study showed that CPC-chitosan scaffold was a promising carrier for HPL delivery, and HPL in CPC exerted excellent promoting effects on hPDLSCs for bone tissue engineering for the first time. The novel hPDLSC-CPC-chitosan-HPL construct has great potential for orthopedic, dental and maxillofacial regenerative applications.

Application of platelet-rich plasma and platelet lysate in the treatment of experimental lymphocutaneous sporotrichosi

Background and Purpose:

Sporotrichosis is a subcutaneous and chronic fungal infection that is caused by a dimorphic fungus, namely Sporothrix schenckii sensu lato. Lymphocutaneous sporotrichosis is the most clinical form, which accounts for nearly 80% of the cases of cutaneous sporotrichosis. Platelets contain several substances with antimicrobial properties. Regarding this, the present study was performed to investigate the effect of blood-based biomaterials, especially platelets in the treatment of lymphocutaneous sporotrichosis.

Materials and Methods:

This study was performed on 12 golden hamsters, divided into three groups of control, platelet-rich plasma, and platelet lysate. For the purpose of the study, Sporothrix conidia suspension was injected subcutaneously on the back of the animals. After the induction of subcutaneous lesions, the Gomori methenamine silver method was applied to verify lymphocutaneous sporotrichosis. Subsequently, plasma-rich platelet and platelet lysate were injected into the created lesions in the animals in 3-day intervals (due to the short lifetime of platelets). In the final sage, skin tissue samples were examined to check for the presence of yeast cells and their quantification.

Results:

The data were indicative of the presence of yeast cells with/without bud in the tissue of lymphocutaneous sporotrichosis lesions in the infected animals. Histological investigation revealed that each of the two biomaterials under study (i.e., plasma-rich platelet and platelet lysate) played a positive role in the removal of the yeast cells of sporotrichosis.

Conclusion:

The results of this study showed that both plasma-rich platelet and platelet lysate were able to effectively prevent from the progression of cutaneous sporotrichosis. Accordingly, much attention has been given to new therapies, including treatment with blood-derived biomaterials.

Effect of platelet-rich plasma concentrations on the proliferation of periodontal cells: An in vitro study

Objective:

The purpose of this study was to evaluate the effect of different concentrations of platelet-rich plasma (PRP) on the proliferation of undifferentiated periodontal ligament (PDL) fibroblasts.

Materials and Methods:

The undifferentiated PDL fibroblasts were obtained from two healthy human premolar teeth and cultured in Dulbecco's modified Eagle's medium. Cell wells were divided into five groups. Experimental groups received 0.1%, 5%, or 50% PRP; the positive and negative control groups were cultured in fetal bovine serum (FBS) 12% and in a medium without FBS 12%, respectively. The plates were incubated at 37°C for 1, 2, 3, 4, and 7 days. PDL cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay. Statistical analysis of the data was accomplished using repeated measure ANOVA and Tukey's test. P < 0.05 was considered statistically significant.

Results:

The 5% PRP had the greatest effect on undifferentiated fibroblast proliferation, which was significant on the 3^rd day. There was no significant difference between 0.1% PRP and positive control during the first 3 days. The group with 50% PRP presented significantly lower proliferation, compared to other experimental and control groups.

Conclusions:

It may be concluded that the growth-stimulating effect of PRP is dose dependent with the best results in low concentrations.

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.

The Clinical Use of Biologics in the Knee Lesions: Does the Patient Benefit?

PURPOSE OF REVIEW

Overview the outcomes of the latest use of platelet-rich plasma (PRP) for the treatment of knee lesions in the clinics and discuss the challenges and limitations.

RECENT FINDINGS

Recent clinical studies mainly indicate there may be benefit of PRP usage for the treatment of knee lesions. As an autologous source of bioactive components, PRP has been shown to be typically safe, free of major adverse outcomes. The use of PRP has been continuously increasing, and some well-designed, double-blinded, placebo-controlled clinical trials have been published. Clinical outcomes relating to PRP usage are multifactorial and depend on the severity of the lesion and patient characteristics. Although PRP is safe to use and it can be easily applied in the clinics, case-specific considerations are needed to determine whether PRP could be beneficial or not. If the use of PRP is favored, then, the configuration/optimization of the preparation and administration/delivery strategy with or without a concomitant treatment may further enhance the clinical outcomes and patients' experience.

Therapeutic strategies for enhancing angiogenesis in wound healing

The enhancement of wound healing has been a goal of medical practitioners for thousands of years. The development of chronic, non-healing wounds is a persistent medical problem that drives patient morbidity and increases healthcare costs. A key aspect of many non-healing wounds is the reduced presence of vessel growth through the process of angiogenesis. This review surveys the creation of new treatments for healing cutaneous wounds through therapeutic angiogenesis. In particular, we discuss the challenges and advancement that have been made in delivering biologic, pharmaceutical and cell-based therapies as enhancers of wound vascularity and healing.