Tissue regeneration and in loco administration of platelet derivatives: clinical outcome, heterogeneous products, and heterogeneity of the effector mechanisms

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.

The usefulness of platelet-rich plasma to manage skin wounds: A meta-analysis

A meta-analysis investigation to measure the usefulness of platelet-rich plasma (PRP) to manage skin wounds (SWs). A comprehensive literature inspection till February 2023 was applied and 1349 interrelated investigations were reviewed. The 22 chosen investigations enclosed animals' SWs were in the chosen investigations' starting point, 3348 of them were treated with PRP, and 2259 were control. Odds ratio (OR) in addition to 95% confidence intervals (CIs) were used to compute the value of the usefulness of PRP to manage SWs by the dichotomous and continuous approaches and a fixed or random model. PRP significantly higher percent of decreases in open wound area (OWA) (MD, 10.07; 95% CI, 6.55-13.59, P < 0.001), and lower healing time (HT) (MD, -6.31; 95% CI, -10.69 to -1.93, P = 0.005) compared to control in animals' SWs. PRP had a significantly higher percent of decreases in OWA and lower HT compared to control in animals' SWs. However, caused of the small sample sizes of several chosen investigations for this meta-analysis, care must be exercised when dealing with its values.

Ultrasound-guided versus palpation-guided platelet-rich plasma injection for the treatment of chronic lateral epicondylitis: A prospective, randomized study

OBJECTIVES

This study aims to compare the effectiveness of palpation-guided and ultrasound (US)-guided platelet-rich plasma (PRP) injections in patients with chronic lateral epicondylitis (LE).

PATIENTS AND METHODS

Between January 2021 and August 2021, a total of 60 patients (34 males, 26 females; mean age: 40.5±10.9 years; range, 22 to 64 years) diagnosed with chronic LE were included. The patients were randomly allocated to either the palpation-guided (n=30) or the US-guided injection group (n=30) before they received PRP injection. All patients were assessed using the Visual Analog Scale (VAS), Disabilities of the Arm, Shoulder and Hand (DASH) scale, and grip strength at baseline and at one, three, and six months after injection.

RESULTS

Baseline sociodemographic and clinical variables were statistically similar between two groups (p>0.05). The VAS and DASH scores improved significantly after the injection at each control, as well as grip strength in both groups (p<0.001). No statistically significant difference was found between the groups regarding VAS and DASH scores, and grip strength at one, three, and six months post-injection (p>0.05). No significant complication related to the injection was observed in any of the groups.

CONCLUSION

This study demonstrates that both palpation-guided and US-guided PRP injection protocols can improve clinical symptoms and functional parameters of patients with chronic LE.

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.

Magnetic resonance imaging and clinically controlled improvement of a combined autologous conditioned plasma combined with rh collagen type I injections in lateral epicondylitis

The purpose of the study was to investigate the effect of combined autologous conditioned plasma and recombinant human collagen type I injections on lateral epicondylitis. Outcome was measured in 5 patients before the single application of ACP+rhCollagen type I (Arthrex ACP® Tendo) and after 10.60±3.58wks by means of (i) the Visual Analogue Scale for pain, (ii) range of motion for wrist extension/flexion as well as supination/pronation, and (iii) MRI-scans. VAS-scores significantly decreased from 6.40±1.14 at baseline to 1.80±2.49 at follow- up, and the effect was very large (p=0.04, d^z=2.22). In addition, range of motion either improved or remained unrestricted, and MRI-scans showed healing of the extensor carpi radialis brevis tendon in most cases. A combined ACP+rhCollageninjection successfully reduces pain in lateral epicondylitis. Due to the small sample size, however, these promising preliminary results need further investigation in future research.

Autologous Platelet-Rich Plasma Enhances the Healing of Large Cutaneous Wounds in Dogs

Platelet-rich plasma (PRP) is known to play a crucial role in skin wound healing, in both Human and Veterinary Medicine. Remarkably, until now, no studies have reported PRP treatment in subacute full-thickness skin wounds of the dog. The aim of this study was to evaluate the effects of two consecutive applications of autologous PRP, with the second application after 15 days, in 6 dogs showing large subacute skin wounds. The percentage of contraction, re-epithelialization and healing in all treated patients indicated that no complications or side effects, associated with consecutive PRP treatments, occurred in any patient and all wounds achieved complete closure and re-epithelialization. Our results suggest a positive effect of repeated autologous topical PRP treatments in large cutaneous subacute wounds of different etiology. Therefore, this PRP treatment could represent a simple, cost-effective, and valid alternative to promote healing processes in subacute large wounds cases in dogs.

Platelet-rich plasma to treat experimentally-induced skin wounds in animals: A systematic review and meta-analysis

The objective of the study was to review current literature to determine whether the topical application of platelet-rich plasma (PRP) promotes healing in experimentally-induced full-thickness skin wounds in animals. The hypothesis was that the adjunct of PRP has a positive effect on wound healing. An electronic search was carried out on the following databases: Web of Science, Cochrane Library, PubMed, Research Gate, Cochrane Wounds Group, Veterinary Information Network. No publication date nor language restrictions were applied. Randomised and not randomised controlled clinical trials comparing PRP with placebo or with other treatments were included. The reduction of open wound area in PRP-treated (test) wounds compared to control wounds was the primary outcome. Secondary outcomes were healing time and number of healed cases in test group compared to control. The following effect sizes were calculated: the Hedges' g for continuous variables; the odds ratio for binary data. Eighteen controlled clinical trials were included in the qualitative and quantitative synthesis, with a total of 661 wounds. All studies were published in the period 2007-2016. Eight studies were carried out on rodent/lagomorph mammals and 10 on non-rodent/lagomorph mammals. In all included studies, control wounds underwent placebo or were left untreated. The PRP group showed a better healing performance than the control group in each outcome. The effect size was statistically significant considering the primary outcome and the overall aggregation of the three outcomes. The effect size, although in favour of the treatment with PRP, was not significant considering the healing time and the number of healings. The overall heterogeneity was mild or moderate. Five studies reported a high risk of selection bias. The publication bias was always mild or absent. The results support the hypothesis of the positive effects of the PRP when compared to control groups in the treatment of experimentally-induced full-thickness skin wounds in animals. PRP can therefore be considered an effective adjunctive therapy in stimulating second intention healing of acute wounds in healthy animals.

Ultrasound-Guided Injection Therapy of Achilles Tendinopathy With Platelet-Rich Plasma or Saline: A Randomized, Blinded, Placebo-Controlled Trial

BACKGROUND

Achilles tendinopathy (AT) is a common and difficult to treat musculoskeletal disorder.

PURPOSE

To examine whether 1 injection of platelet-rich plasma (PRP) would improve outcomes more effectively than placebo (saline) after 3 months in patients with AT.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 24 patients with chronic AT (median disease duration, 33 months) were randomized (1:1) to receive either a blinded injection of PRP (n = 12) or saline (n = 12). The primary endpoint was improvement in Victorian Institute of Sports Assessment-Achilles (VISA-A) score at 3 months. Secondary outcomes were pain at rest, pain while walking, pain when tendon was squeezed, ultrasonographic changes in tendon thickness, and color Doppler activity. Patients were informed that they could drop out after 3 months if they were dissatisfied with the treatment.

RESULTS

After 3 months, all 24 patients were reassessed (no dropouts). No difference between the PRP and the saline group could be observed with regard to the primary outcome (VISA-A score: mean difference [MD], -1.3; 95% CI, -17.8 to 15.2; P = .868). Secondary outcomes were pain at rest (MD, 1.6; 95% CI, -0.5 to 3.7; P = .137), pain while walking (MD, 0.8; 95% CI, -1.8 to 3.3; P = .544), pain when tendon was squeezed (MD, 0.3; 95% CI, -0.2 to 0.9; P = .208), color Doppler activity (MD, 0.3; 95% CI, -0.2 to 0.8; P = .260), and tendon thickness (MD, 0.8 mm; 95% CI, 0.1 to 1.6 mm; P = .030). After the 3-month follow-up, a large dropout was observed: 75% of patients in the PRP group and 33% in the saline group.

CONCLUSION

PRP injection did not result in an improved VISA-A score over a 3-month period in patients with chronic AT compared with placebo. The only secondary outcome demonstrating a statistically significant difference between the groups was change in tendon thickness; this difference indicates that a PRP injection could increase tendon thickness compared with saline injection. The conclusions are limited to the 3 months after treatment owing to the large dropout rate.

Investigating the effect of intra-articular PRP injection on pain and function improvement in patients with distal radius fracture

INTRODUCTION

Distal radius fractures are common injuries that cause pain and disability. There is a clear need for biomedical engineering research to develop novel strategies to improve functional results following intra-articular distal radius fractures. However, no pharmacotherapeutic agent has been investigated to resolve this problem. The aim of this study was to evaluate whether the platelet-rich plasma (PRP) can be considered a novel additional therapy to improve the outcomes of this injury.

HYPOTHESIS

Pain reduction and functional improvement can be noticed after PRP use in distal radius fracture.

MATERIALS AND METHODS

A randomized trial study was designed with 30 patients who had intra-articular distal radius fractures (Frykman type 3, 4, 7, 8). Closed reduction and percutaneous pinning under guide of fluoroscopy were done for them. Fifteen cases received intra-articular autologus PRP. Patients were followed for 3 and 6 months and "patient-rated wrist evaluation" (PRWE) questionnaire was completed and range of motion of the wrist was measured.

RESULTS

The mean of pain score and the score of specific and usual activities at 3 months follow-up in the case group and in the control group were (8.33 versus 19.67), (10.66 versus 26.8), and (6.2 versus 13.4), respectively. The mean of pain score and score of specific and usual activities at 6 months follow-up in the case group and in the control group were (3.6 versus 12), (3 versus 15.7), and (1.2 versus 6.8), respectively. The case group was significantly different from the control group. The mean of loss of flexion and extension of the wrist at 3 months follow-up in the case group was significantly different from the control group as well.

CONCLUSION

PRP may have significant effect on reduction of pain and amount of difficulty in functions, including specific and usual activities after intra-articular distal radius fractures.

LEVEL OF EVIDENCE

Level III, Therapeutic trial.

Human platelet releasates combined with polyglycolic acid scaffold promote chondrocyte differentiation and phenotypic maintenance

In the present study, we aimed to demonstrate the differentiating properties of platelet-rich plasma releasates (PRPr) on human chondrocytes seeded on a polygtlycolic acid (PGA) 3D scaffold. Gene expression and biochemical analysis were carried out to assess the improved quality of our PGA-based cartilage constructs supplemented with PRPr. We observed that the use of PRPr as cell cultures supplementation to PGA-chondrocyte constructs may promote chondrocyte differentiation, and thus may contribute to maintaining the chondrogenic phenotype longer than conventional supplementation by increasing high levels of important chondrogenic markers (e.g. sox9, aggrecan and type II collagen), without induction of type I collagen. Moreover, our constructs were analysed for the secretion and deposition of important ECM molecules (sGAG, type II collagen, etc.). Our results indicate that PRPr supplementation may synergize with PGA-based scaffolds to stimulate human articular chondrocyte differentiation, maturation and phenotypic maintenance.

Multicentre standardisation of a clinical grade procedure for the preparation of allogeneic platelet concentrates from umbilical cord blood

BACKGROUND

In addition to a largely prevalent use for bleeding prophylaxis, platelet concentrates from adult blood have also been used for many years to prepare platelet gels for the repair of topical skin ulcers. Platelet gel can be obtained by activation of fresh, cryopreserved, autologous or allogeneic platelet concentrates with calcium gluconate, thrombin and/or batroxobin. The high content of tissue regenerative factors in cord blood platelets and the widespread availability of allogeneic cord blood units generously donated for haematopoietic transplant but unsuitable for this use solely because of low haematopoietic stem cell content prompted us to develop a national programme to standardise the production of allogeneic cryopreserved cord blood platelet concentrates (CBPC) suitable for later preparation of clinical-grade cord blood platelet gel.

MATERIALS AND METHODS

Cord blood units collected at public banks with total nucleated cell counts <1.5×10(9), platelet count >150×10(9)/L and volume >50 mL, underwent soft centrifugation within 48 hours of collection. Platelet-rich plasma was centrifuged at high speed to obtain a CBPC with target platelet concentration of 800-1,200×10(9)/L, which was cryopreserved, without cryoprotectant, below -40 °C.

RESULTS

During 14 months, 13 banks produced 1,080 CBPC with mean (± standard deviation) volume of 11.4±4.4 mL and platelet concentration of 1,003±229×10(9)/L. Total platelet count per CBPC was 11.3±4.9×10(9). Platelet recovery from cord blood was 47.7±17.8%. About one-third of cord blood units donated for haematopoietic transplant could meet the requirements for preparation of CBPC. The cost of preparation was € 160.92/CBPC. About 2 hours were needed for one technician to prepare four CBPC.

DISCUSSION

This study yielded valuable scientific and operational information regarding the development of clinical trials using allogeneic CBPC.

Effect of microfracture and autologous-conditioned plasma application in the focal full-thickness chondral defect of the knee: an experimental study on rabbits

Purpose

The aim of the present study was to evaluate the effect of microfracture and intraarticular autologous conditioned plasma (ACP) injection on cartilage regeneration in a focal full-thickness chondral defect model created in the knee joint.

Methods

Full-thickness chondral defects of 3 × 6 mm² were surgically created in right medial femoral condyles (MFC) of New Zealand rabbits, and the rabbits were then divided into three groups according to treatment: Group 1 received only microfracture (mfx), Group 2 received mfx plus intraarticular ACP, and Group 3 received mfx; the defect was covered by the periosteum, and then, ACP was applied subperiosteally and intraarticularly. Twelve weeks after injection, the animals were sacrificed and the femoral condyles were evaluated macroscopically and histologically by hematoxylin-eosin staining. Then, histological sections were scored using the International Cartilage Repair Society (ICRS) visual histological scale.

Results

Findings showed that in both mfx/ACP-treated groups, the defects were filled regularly and smoothly, the defects had a greater fill and good integration into the surrounding host tissue, and the repair matrix had more hyaline-like character. On the other hand, defects were filled with an irregular, fibrous cartilage in the mfx-treated group. Histological scores in Group 2 and Group 3 were better compared to Group 1.

Conclusion

In the present study, we were able to demonstrate a beneficial effect of intraarticular administration of ACP as a coadjuvant of microfractures in order to regenerate hyaline-like cartilage in full-thickness chondral lesions in a rabbit model.

Platelet-rich plasma injections for the treatment of refractory Achilles tendinopathy: results at 4 years

BACKGROUND

Chronic Achilles tendinopathy is responsible for a severe reduction in physical performance and persistent pain. There is currently a number of therapeutic options and the local administration of growth factors is an emerging treatment strategy. In particular, platelet-rich plasma (PRP) is a widely used way to provide a local regenerative stimulus for tendon healing. The aim of this study was to document the mid-term results obtained after treating recalcitrant Achilles tendinopathy with injections of high concentrate, leucocyte-rich PRP.

MATERIALS AND METHODS

Twenty-seven patients (mean age: 44.6 years; 22 men and 5 women) affected by chronic mid-portion Achilles tendinopathy (7 bilateral, for a total of 34 tendons), refractory to previous treatments, were enrolled. Patients were treated with three ultrasound-guided intra-tendinous injections of PRP at 2-week intervals. Patients were prospectively evaluated at baseline, and then at 2, 6, and up to a mean of 54.1 months of follow-up (minimum 30 months), using the following tools: Blanzina, VISA-A, EQ-VAS for general health, and Tegner scores.

RESULTS

The VISA-A score showed a significant improvement: the baseline score of 49.9±18.1 increased to 62.9±19.8 at 2 months (p=0.002), with a further improvement at 6 months (84.3±17.1, p<0.0005), and stable results at 4.5 years (90.0±13.9). The EQ-VAS score also showed a similar positive trend. An evaluation of the activity level confirmed these findings, showing a significant improvement in the Tegner score over time (p=0.017 for the final evaluation). The longer duration of symptoms before treatment was associated with a slower return to sport (p=0.041).

DISCUSSION

PRP injections produced good overall results for the treatment of chronic recalcitrant Achilles tendinopathy with a stable outcome up to a medium-term follow-up. Longer symptom duration was related with a more difficult return to sporting activity.

Are multiple platelet-rich plasma injections useful for treatment of chronic patellar tendinopathy in athletes? a prospective study

BACKGROUND

Chronic patellar tendinopathy (PT) is one of the most common overuse knee disorders. Platelet-rich plasma (PRP) appears to be a reliable nonoperative therapy for chronic PT.

PURPOSE

To evaluate clinical and radiological outcomes of 3 consecutive ultrasound (US)-guided PRP injections for the treatment of chronic PT in athletes.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 28 athletes (17 professional, 11 semiprofessional) with chronic PT refractory to nonoperative management were prospectively included for US-guided pure PRP injections into the site of the tendinopathy. The same treating physician at a single institution performed 3 consecutive injections 1 week apart, with the same PRP preparation used. All patients underwent clinical evaluation, including the Victorian Institute of Sport Assessment-Patella (VISA-P) score, visual analog scales (VAS) for pain, and Lysholm knee scale before surgery and after return to practice sports. Tendon healing was assessed with MRI at 1 and 3 months after the procedure.

RESULTS

The VISA-P, VAS, and Lysholm scores all significantly improved at the 2-year follow-up. The average preprocedure VISA-P, VAS, and Lysholm scores improved from 39 to 94 (P < .001), 7 to 0.8 (P < .0001), and 60 to 96 (P < .001), respectively, at the 2-year follow-up. Twenty-one of the 28 athletes returned to their presymptom sporting level at 3 months (range, 2-6 months) after the procedure. Follow-up MRI assessment showed improved structural integrity of the tendon at 3 months after the procedure and complete return to normal structural integrity of the tendon in 16 patients (57%). Seven patients did not recover their presymptom sporting level (among them, 6 were considered treatment failures): 3 patients returned to sport at a lesser level, 1 patient changed his sport activity (for other reasons), and 3 needed surgical intervention.

CONCLUSION

In this study, application of 3 consecutive US-guided PRP injections significantly improved symptoms and function in athletes with chronic PT and allowed fast recovery to their presymptom sporting level. The PRP treatment permitted a return to a normal architecture of the tendon as assessed by MRI.

Autologous platelet gel to treat chronic decubital ulcers: a randomized, blind controlled clinical trial in dogs

OBJECTIVE

To determine the efficacy of topical application of the autologous platelet gel (PG) in canine chronic protracted decubital ulcers.

STUDY DESIGN

Prospective, randomized, blind controlled clinical trial.

ANIMALS

Dogs (n = 18) with bilateral chronic wounds caused by protracted decubitus ulcers.

METHODS

For each dog, wound side was randomized to receive either platelet gel (group PG) every 5 days for 5 dressing changes, or paraffin gauzes dressings (group C), as negative control. Wound healing and wound surfaces were compared at admission and then evaluated every 5th day, until day 25. Outcome variables were: open wound area, reduction of open wound surface compared to admission and to each preceding dressing change, time to complete epithelialization.

RESULTS

Significant differences in healing process were observed at day 5 and continued throughout the entire study period (P < .00001). At 25 days, mean percent reduction in wound area was 93.5% in group PG and 13.2% in group C (P < .00001).

CONCLUSIONS

Appropriately prepared autologous PG, an inexpensive, readily available blood derivative, applied topically results in more rapid healing of chronic non-healing decubital ulcers in dogs than those treated by use of paraffin-impregnated gauzes.

The effect of platelet-rich plasma on osteochondral defects treated with mosaicplasty

PURPOSE

This study investigated the efficacy of platelet-rich plasma (PRP) on articular surfaces on which the mosaicplasty technique was performed. Our hypothesis was that PRP can accelerate the osseointegration process and enhance the quality of articular integrity after the mosaicplasty procedure.

METHODS

Standard defects were created in the femoral groove of both patellofemoral joints of 12 New Zealand rabbits. PRP solution was placed inside the defect before fixation of the osteochondral autografts and injected inside the involved joint after capsular closure of the tested knees. The contralateral knees served as the control sides. The animals were euthanized three or six weeks after mosaicplasty, and both limbs were assessed according to Pineda's histological grading scale. Significance level was set at p ≤ 0.05 a priori, and the Mann-Whitney U test was used for statistical analysis.

RESULTS

Histologic findings at the interface between the transferred autograft and the original cartilage revealed better integration of the adjacent surfaces in the mosaicplasty with PRP group three weeks after the procedure; the difference was significant (p < 0.05). However, no significant difference in the transition zone was observed between the groups six weeks after the experiment (p = 0.59).

CONCLUSIONS

Our animal model showed that adjunctive use of PRP produced a better healing response and resulted in superior histological scores after three weeks compared with the mosaicplasty-only procedure. Interpretation of our results is important in terms of rapid return to previous activity levels. Thus, application of PRP can represent a valid therapeutic option for improving the efficacy of mosaicplasty by stimulating the local healing response.

Effect of platelet lysate on human cells involved in different phases of wound healing

Background

Platelets are rich in mediators able to positively affect cell activity in wound healing. Aim of this study was to characterize the effect of different concentrations of human pooled allogeneic platelet lysate on human cells involved in the different phases of wound healing (inflammatory phase, angiogenesis, extracellular matrix secretion and epithelialization).

Methodology/Principal Findings

Platelet lysate effect was studied on endothelial cells, monocytes, fibroblasts and keratinocytes, in terms of viability and proliferation, migration, angiogenesis, tissue repair pathway activation (ERK1/2) and inflammatory response evaluation (NFκB). Results were compared both with basal medium and with a positive control containing serum and growth factors. Platelet lysate induced viability and proliferation at the highest concentrations tested (10% and 20% v/v). Whereas both platelet lysate concentrations increased cell migration, only 20% platelet lysate was able to significantly promote angiogenic activity (p<0.05 vs. control), comparably to the positive control. Both platelet lysate concentrations activated important inflammatory pathways such as ERK1/2 and NFκB with the same early kinetics, whereas the effect was different for later time-points.

Conclusion/Significance

These data suggest the possibility of using allogeneic platelet lysate as both an alternative to growth factors commonly used for cell culture and as a tool for clinical regenerative application for wound healing.

Efficacy of ultrasound-guided intra-articular injections of platelet-rich plasma versus hyaluronic acid for hip osteoarthritis

Intra-articular injections of platelet-rich plasma (PRP) and hyaluronic acid (HA) represent efficacious medical treatments for osteoarthritis (OA), although no comparative study on long-term efficacy in hip OA exists. The goals of the current study were to compare the clinical efficacy of PRP vs HA at 12 months of follow-up in patients with hip OA and evaluate the influence of the type of infiltration and patient age, sex, body mass index, and degree of OA on temporal clinical evolution. One hundred patients with chronic unilateral symptomatic hip OA were consecutively enrolled and randomly assigned to 1 of 2 groups: group A received PRP and group B received HA administered via intra-articular ultrasound-guided injections. Patients were evaluated at baseline and after 1, 3, 6, and 12 months using the Harris Hip Score (HHS) and visual analog scale (VAS). An overall improvement was detected in both groups between 1- and 3-month follow-up. Despite a slightly progressive worsening between 6- and 12-month follow-up, the final clinical scores remained higher compared with baseline (P<.0005), with no significant differences between PRP and HA. Regarding clinical temporal evolution, multivariate analysis showed that HHS was not influenced by the type of infiltration, patient age, sex, body mass index, or degree of OA, whereas a significant association was detected between OA grade IV and VAS evolution (P<.0005). Intra-articular injections of PRP are efficacious in terms of functional improvement and pain reduction but are not superior to HA in patients with symptomatic hip OA at 12-month follow-up.

Functional and differential proteomic analyses to identify platelet derived factors affecting ex vivo expansion of mesenchymal stromal cells

Background

Multilineage differentiation, immunomodulation and secretion of trophic factors render mesenchymal stromal cells (MSC) highly attractive for clinical application. Human platelet derivatives such as pooled human platelet lysate (pHPL) and thrombin-activated platelet releasate in plasma (tPRP) have been introduced as alternatives to fetal bovine serum (FBS) to achieve GMP-compliance. However, whereas both pHPL and tPRP support similar proliferation kinetics of lipoaspirate-derived MSC (LA-MSC), only pHPL significantly accelerates bone marrow-derived MSC (BM-MSC) expansion. To identify functionally bioactive factors affecting ex vivo MSC expansion, a differential proteomic approach was performed and identified candidate proteins were evaluated within a bioassay.

Results

Two dimensional difference gel electrophoresis (2D-DIGE), MALDI-TOF analyses and complementary Western blotting revealed 20 differential protein species. 14 candidate proteins occured at higher concentrations in pHPL compared to tPRP and 6 at higher concentrations in tPRP. The candidate proteins fibrinogen and apolipoprotein A1 differentially affected LA- and BM-MSC proliferation.

In a second set of experiments, reference cytokines known to foster proliferation in FBS were tested for their effects in the human supplements. Interestingly although these cytokines promoted proliferation in FBS, they failed to do so when added to the humanized system.

Conclusions

The differential proteomic approach identified novel platelet derived factors differentially acting on human MSC proliferation. Complementary testing of reference cytokines revealed a lack of stimulation in the human supplements compared to FBS. The data describe a new coherent approach to combine proteomic technologies with functional testing to develop novel, humanized, GMP-compliant conditions for MSC expansion.

Bone marrow aspiration concentrate and platelet rich plasma for osteochondral repair in a porcine osteochondral defect model

BACKGROUND

Bone marrow aspiration concentrate (BMAC) may possess a high potency for cartilage and osseous defect healing because it contains stem cells and multiple growth factors. Alternatively, platelet rich plasma (PRP), which contains a cocktail of multiple growth factors released from enriched activated thrombocytes may potentially stimulate the mesenchymal stem cells (MSCs) in bone marrow to proliferate and differentiate.

METHODS

A critical size osteochondral defect (10×6 mm) in both medial femoral condyles was created in 14 Goettinger mini-pigs. All animals were randomized into the following four groups: biphasic scaffold alone (TRUFIT BGS, Smith & Nephew, USA), scaffold with PRP, scaffold with BMAC and scaffold in combination with BMAC and PRP. After 26 weeks all animals were euthanized and histological slides were cut, stained and evaluated using a histological score and immunohistochemistry.

RESULTS

The thrombocyte number was significantly increased (p = 0.049) in PRP compared to whole blood. In addition the concentration of the measured growth factors in PRP such as BMP-2, BMP-7, VEGF, TGF-β1 and PDGF were significantly increased when compared to whole blood (p<0.05). In the defects of the therapy groups areas of chondrogenic tissue were present, which stained blue with toluidine blue and positively for collagen type II. Adding BMAC or PRP in a biphasic scaffold led to a significant improvement of the histological score compared to the control group, but the combination of BMAC and PRP did not further enhance the histological score.

CONCLUSIONS

The clinical application of BMAC or PRP in osteochondral defect healing is attractive because of their autologous origin and cost-effectiveness. Adding either PRP or BMAC to a biphasic scaffold led to a significantly better healing of osteochondral defects compared with the control group. However, the combination of both therapies did not further enhance healing.

Platelet-rich plasma for the treatment of patellar tendinopathy: clinical and imaging findings at medium-term follow-up

PURPOSE

The purpose of this study was to evaluate the efficacy of multiple platelet-rich plasma (PRP) injections on the healing of chronic refractory patellar tendinopathy, and report the quality and duration of the clinical improvement up to a medium-term follow-up.

METHODS

Forty-three patients (mean age, 30.6 years; mean BMI, 24.7; 42 men, one woman) affected by chronic patellar proximal tendinopathy were enrolled in this trial. Eleven patients were affected by bilateral tendinopathy. They underwent three ultrasound guided intra-tendinous injections of five millilitres PRP, two weeks apart from each other. Patients were prospectively evaluated initially, then after two, six, and up to mean 48.6 ± 8.1 months of follow-up (minimum evaluation at 36 months). The following evaluation tools were used: Blanzina, VISA-P, EQ-VAS for general health, and Tegner scores. Patients' overall satisfaction and time to return to sport were also reported.

RESULTS

Good and stable results were documented over time, with the VISA-P score increasing from 44.1 ± 15.6 at baseline to 61.4 ± 22.2 at two months, 76.6 ± 25.4 at six months, and 84.3 ± 21.6 at four years' follow-up. The same trend was confirmed by the other scores used, and 80 % of the patients were satisfied and returned to previous sports activities. Significantly poorer results were obtained in patients with a longer history of symptoms, and poor results were also observed in bilateral lesions. No correlation between ultrasonographic and clinical findings could be found.

CONCLUSIONS

Multiple injections of PRP provided a good clinical outcome for the treatment of chronic recalcitrant patellar tendinopathy with stable results up to medium-term follow-up. Patients affected by bilateral pathology and presenting a long history of pain obtained significantly poorer results.

Synovial membrane-derived mesenchymal stem cells supported by platelet-rich plasma can repair osteochondral defects in a rabbit model

PURPOSE

The aim of this study was to determine the in vivo effectiveness of synovial membrane-derived mesenchymal stem cell (SDSC)-encapsulated injectable platelet-rich plasma (PRP) gel in the repair of damaged articular cartilage in the rabbit.

METHODS

An osteochondral defect was created in the trochlear groove of the rabbit femur, and the defects were divided into 3 treatment groups: untreated control group, PRP group, and PRP-SDSC group. After 4, 12, and 24 weeks, the tissue specimens were assessed by macroscopic examination and histologic evaluation and stained immunohistochemically for type II collagen and proliferating cell nuclear antigen. In addition, total glycosaminoglycan content was determined at 24 weeks.

RESULTS

Rabbit PRP contained a high concentration of platelets and high concentration of growth factors compared with those in whole blood. Twenty-four weeks after transplantation, there was fibrous tissue in the control group. In both the PRP group and the PRP-SDSC group, the defects were repaired with hyaline cartilage and exhibited significantly higher safranin O staining, type II collagen immunostaining, glycosaminoglycan content, cumulative histologic scores, and number of proliferating cell nuclear antigen-positive cells. However, incomplete bone regeneration and irregular cartilage surface integration were observed in the PRP group.

CONCLUSIONS

Our results indicate that SDSC-embedded PRP gel could successfully resurface the defect with cartilage and restore the subchondral bone in the rabbit model.

CLINICAL RELEVANCE

This study indicates that in an animal model, the application of PRP and SDSC in combination for the treatment of local cartilage defects appears promising; however, PRP-SDSC products might be more or less appropriate to treat different types of tissues and pathologies. The clinical efficacy of PRP remains under debate. Therefore further research is needed at both the basic science and clinical levels.

Treatment of lateral epicondylitis with platelet-rich plasma, glucocorticoid, or saline: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Lateral epicondylitis (LE) is a common musculoskeletal disorder for which an effective treatment strategy remains unknown.

PURPOSE

To examine whether a single injection of platelet-rich plasma (PRP) is more effective than placebo (saline) or glucocorticoid in reducing pain in adults with LE after 3 months.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

A total of 60 patients with chronic LE were randomized (1:1:1) to receive either a blinded injection of PRP, saline, or glucocorticoid. The primary end point was a change in pain using the Patient-Rated Tennis Elbow Evaluation (PRTEE) questionnaire at 3 months. Secondary outcomes were ultrasonographic changes in tendon thickness and color Doppler activity.

RESULTS

Pain reduction at 3 months (primary end point) was observed in all 3 groups, with no statistically significant difference between the groups; mean differences were the following: glucocorticoid versus saline: -3.8 (95% CI, -9.9 to 2.4); PRP versus saline: -2.7 (95% CI, -8.8 to 3.5); and glucocorticoid versus PRP: -1.1 (95% CI, -7.2 to 5.0). At 1 month, however, glucocorticoid reduced pain more effectively than did both saline and PRP; mean differences were the following: glucocorticoid versus saline: -8.1 (95% CI, -14.3 to -1.9); and glucocorticoid versus PRP: -9.3 (95% CI, -15.4 to -3.2). Among the secondary outcomes, at 3 months, glucocorticoid was more effective than PRP and saline in reducing color Doppler activity and tendon thickness. For color Doppler activity, mean differences were the following: glucocorticoid versus PRP: -2.6 (95% CI, -3.1 to -2.2); and glucocorticoid versus saline: -2.0 (95% CI, -2.5 to -1.6). For tendon thickness, mean differences were the following: glucocorticoid versus PRP: -0.5 (95% CI, -0.8 to -0.2); and glucocorticoid versus saline: -0.8 (95% CI, -1.2 to -0.5).

CONCLUSION

Neither injection of PRP nor glucocorticoid was superior to saline with regard to pain reduction in LE at the primary end point at 3 months. However, injection of glucocorticoid had a short-term pain-reducing effect at 1 month in contrast to the other therapies. Injection of glucocorticoid in LE reduces both color Doppler activity and tendon thickness compared with PRP and saline.

Platelet-rich plasma treatment in symptomatic patients with knee osteoarthritis: preliminary results in a group of active patients

Background:

With increasing frequency, platelet-rich plasma (PRP) preparations have been used to treat cartilage lesions to regenerate tissue homeostasis and retard the progression of knee osteoarthritis (OA).

Purpose:

To determine the effectiveness of intra-articular PRP injections in active patients with knee OA and to evaluate clinical outcomes in patients with and without previous surgical treatment for cartilage lesions.

Study Design:

Case series.

Materials and Methods:

Fifty patients with knee OA were followed for a minimum of 12 months. All were treated with 2 intra-articular injections of autologous PRP. Twenty-five patients had undergone a previous operative intervention for cartilage lesions, whereas 25 had not. Operated patients had undergone either cartilage shaving or microfracture. Multiple evaluative scores were collected at pretreatment and at 6 and 12 months posttreatment. The required sample of patients was determined beforehand by using statistical power analysis; International Knee Documentation Committee (subjective) score was defined as the primary parameter. A P value of less than 0.05 was considered statistically significant. General linear model–repeated measure test evaluated within-time improvement for each variable for all patients. Post hoc test with Bonferroni adjustment for multiple comparisons was performed to investigate the significance in improvement within time evaluations for each variable for the total sample. The differences in improvement between operated and nonoperated patients were also investigated, as were those between sexes.

Results:

All patients showed significant improvement in all scores at 6 and 12 months (P < 0.01) and returned to previous activities. No significant difference in improvement was found between the evaluated subgroups (P < 0.01).

Conclusions:

The PRP treatment showed positive effects in patients with knee OA. Operated and nonoperated patients showed significant improvement by means of diminishing pain and improved symptoms and quality of life.

Clinical Relevance:

There are only a few studies of PRP treatment for cartilage on osteoarthritic knees. Different PRP products might be more or less appropriate to treat different types of tissues and pathologies. The clinical efficacy of PRP remains under debate, and a standardized protocol has not yet been established.

A prospective series of patients with chronic Achilles tendinopathy treated with autologous-conditioned plasma injections combined with exercise and therapeutic ultrasonography

Chronic Achilles tendinopathy is a difficult problem to manage, because it can result in significant patient morbidity. We conducted a prospective case series involving 26 patients (2 bilateral cases) with painful and ultrasound-confirmed Achilles tendinopathy for a minimum duration of 6 months. Our objective was to assess whether this condition can be effectively treated with a treatment protocol combining an intratendinous autologous-conditioned plasma injection followed by a standardized rehabilitation protocol. The rehabilitation protocol consisted of full weightbearing in a pneumatic cast boot for 6 weeks, therapeutic ultrasound treatment, and an eccentric exercise program. Our results showed statistically significant improvements in terms of pain (p < .0001), other symptoms (p = .0003), activities of daily living (p = .0002), sports activities (p = .0001), and quality of life (p = .0002). We believe that the use of autologous-conditioned plasma can provide a potential treatment solution for chronic Achilles tendinopathy.

"Reasonable compromise" to define the quality standards of platelet concentrate for non-transfusion use (CPunT)

Platelets concentrate for non-transfusion use (CPunT) is a blood component specific for regenerative medicine. This blood component has found regenerative applications in many clinical fields (orthopedic, plastic surgery, maxillofacial surgery) since platelets contain growth factors, cytokines and bioactive molecules. Plasticity and ease of preparation of this blood component has often led the user to prepare it without using standardized procedures and references to quality product standards, but to evaluate the effectiveness of treatments and to standardize clinical protocols, is essential. The complexity of establish functional and non-functional parameters to define CPunT properties is linked to three fundamental steps: variability and bioavailability of biomolecules content in platelets, variability in product preparation. Then it is very difficult to understand which are the real parameters to evaluate, but it seems a "reasonable compromise" to establish content of platelets×ml (1×10(9)ml) as reference realistic parameter for CPunT qualification.

Repeated platelet concentrate injections enhance reparative response of microfractures in the treatment of chondral defects of the knee: an experimental study in an animal model

PURPOSE

To assess the histology and biomechanics of repair cartilage after microfractures with and without repeated local injections of platelet concentrate for the treatment of full-thickness focal chondral defects of the knee.

METHODS

A full-thickness chondral lesion on the medial femoral condyle was created in 30 sheep and treated with microfractures. Animals were divided into 2 groups, according to postoperative treatment: in group 1 we performed 5 weekly injections of autologous conditioned plasma, whereas group 2 did not undergo further treatments. Animals were killed at 3, 6, and 12 months after treatment. Macroscopic, histologic, and biomechanical evaluations were performed. Differences between groups at each time interval and differences over time within groups were analyzed for each outcome. Significance was set at P < .05.

RESULTS

Group 1 showed significantly better macroscopic, histologic, and biomechanical results than group 2 at each time interval. Analysis of time effect within groups showed that in group 1, quality of repair tissue significantly improved from 3 to 6 months after treatment and remained stable over time for all the outcomes; in group 2 a significant histologic and mechanical deterioration was observed between 6 and 12 months' follow-up.

CONCLUSIONS

Five repeated local injections of autologous conditioned plasma after microfractures in the treatment of full-thickness cartilage injuries promoted a better and more durable reparative response than isolated microfractures, although they did not produce hyaline cartilage.

CLINICAL RELEVANCE

Periodical intra-articular injections of platelet concentrate after microfractures may improve cartilage repair and prevent further degenerative changes.

Platelet gel in oral and maxillofacial surgery: a single-centre experience

BACKGROUND

Platelet gel is a blood product intended for non-transfusion, therapeutic purposes; it is produced by combining platelet concentrate with cryoprecipitate. Platelet gel stimulates tissue growth and is a key player in tissue regeneration. As an allogeneic product, platelet gel is obtained from the blood of a common type O blood donor, with a platelet count >200×10(3)/μL. Most of the beneficial effects of this product are due to the numerous growth factors (PDGF, TGF-β, IGF-1 and IGF-2, EGF, VEGF and FGF) contained in the alpha-granules of platelets. The aim of this study was to confirm that platelet gel is a valuable aid for the surgical repair of alveolar bone loss.

MATERIALS AND METHODS

Our study was carried out on 87 patients with inflammatory or dysembryoplastic osteolytic lesions >2 cm in diameter in jaw bones. For most patients the platelet gel was collected into a 450 mL bag and kept frozen at -40 °C until, whereas for a small group of patients the gel was prepared and activated in the sterile field of the operating theatre.

RESULTS

All of our patients reported a decrease in painful symptoms immediately after surgery. Follow-up showed considerable acceleration of the healing processes in soft tissues and faster bone regeneration.

CONCLUSION

Multicentre studies are needed in order to standardise the methods for producing platelet gel and the clinical use of this product. Furthermore, for research purposes in vitro studies are needed to increase knowledge on the functional network and platelet growth factors and also to investigate the biochemical and molecular mechanisms involved.

Platelet-rich plasma intra-articular injection versus hyaluronic acid viscosupplementation as treatments for cartilage pathology: from early degeneration to osteoarthritis

PURPOSE

The aim of our study is to compare the efficacy of platelet-rich plasma (PRP) and viscosupplementation (hyaluronic acid [HA]) intra-articular injections for the treatment of knee cartilage degenerative lesions and osteoarthritis (OA).

METHODS

The study involved 150 patients affected by cartilage degenerative lesions and early and severe OA. Fifty symptomatic patients were treated with 3 autologous PRP intra-articular injections and were evaluated prospectively at enrollment and at 2- and 6-month follow-up. The results obtained were compared with 2 homogeneous groups of patients treated with HA injections. One group was treated with injections of high-molecular weight HA; the other group was treated with low-molecular weight (LW) HA. International Knee Documentation Committee and EQ VAS scores were used for clinical evaluation; adverse events and patient satisfaction were also recorded.

RESULTS

At 2 months' follow-up, the PRP and LW HA groups showed a similar improvement, with higher results compared with the high-molecular weight HA group (P < .005). At 6 months' follow-up, better results were observed in the PRP group (P < .005). PRP and LW HA treatments offered similar results in patients aged over 50 years and in the treatment of advanced OA. PRP showed a better performance compared with HA in younger patients affected by cartilage lesions or early OA.

CONCLUSIONS

Autologous PRP injections showed more and longer efficacy than HA injections in reducing pain and symptoms and recovering articular function. Better results were achieved in younger and more active patients with a low degree of cartilage degeneration, whereas a worse outcome was obtained in more degenerated joints and in older patients, in whom results similar to those of viscosupplementation have been observed.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Regenerative medicine for the treatment of musculoskeletal overuse injuries in competition horses

PURPOSE

Tissue repair in musculoskeletal injuries is often a slow and sometimes incomplete process. Regenerative medicine based on the use of growth factors (GFs) and cell therapy is aimed at improving the quality and speed of tendon and ligament healing. The aim of this study was to evaluate the potential for the administration of a combination of autologous platelet-rich plasma (PRP) and freshly isolated bone marrow mononucleated cells (BMMNCs) in 13 competition horses affected by overuse musculoskeletal injuries (suspensory ligament desmopathy and superficial flexor tendinopathy) and refractory to other therapies.

METHODS

After ultrasonographic localisation of the lesion, the autologous BMMNC suspension and PRP were injected directly into the core lesion. BMMNC and platelet count as well as growth factors in PRP were measured to determine factors influencing the clinical outcome.

RESULTS

Horses showed a marked improvement in their degree of lameness and 84.6% were able to return to competition. Among all the factors studied, the platelet concentration predicted the healing time: significantly faster recovery (p = 0.049) was observed in cases of PRP with more than 750 × 10(3)/μl platelets.

CONCLUSIONS

Competition horses are involved in highly demanding activities, thus being a similar model for the high mechanical overload typical of human athletes. The promising results obtained suggest that this combined biological approach may be useful even for the treatment of recalcitrant overuse musculoskeletal injuries in highly demanding patients if the appropriate dose of cells and GFs is applied.

Platelet-rich plasma (PRP) to treat sports injuries: evidence to support its use

Tissue repair in musculoskeletal lesions is often a slow and sometimes incomplete process. In sports patients or professional athletes, the impact of musculoskeletal lesions on life and work is great, and the fast recovery of full efficiency and return to competition is of primary importance. The clinical improvement offered by available treatments is not always sufficient for highly demanding patients to return to their previous level of activity. The search for a minimally invasive solution to improve the status of the chondral surface of the injured joint is therefore highly desirable, especially in these patients. Platelet-rich plasma (PRP) is a procedure that allows to obtain a natural concentration of autologous growth factors. The attractive possibility to use the patients' own growth factors to enhance reparative process in tissues with low healing potential, the promising preliminary clinical findings and the safety of these methods, explain the wide application of this biological approach. The aim of this review is to analyse the existing published studies to look for scientific evidence in preclinical studies or in the results obtained through PRP application in humans that supports the efficacy of PRP and its use for the treatment of tendinous, ligamentous, cartilaginous and muscular injuries. The analysis of the literature shows promising preclinical results but contradictory clinical findings for the treatment of sport injuries. High-quality studies are required to confirm these preliminary results and provide scientific evidence to support its use.

Efeito do Plasma Rico em Plaquetas na apoptose pós-traumática de condrócitos

OBJETIVO: Avaliar se a injeção intra-articular de Plasma rico em plaquetas (PRP) pode reduzir a apoptose pós-traumática de condrócitos. MÉTODOS: Foi desenvolvido um estudo experimental duplo-cego com quatro joelhos de coelhos adultos. Após a anestesia, os animais foram submetidos à contusão padronizada dos joelhos. Depois foi injetado 1ml de PRP humano nos dois joelhos esquerdos e 1ml de solução fisiológica (SF) nos dois joelhos direitos. Os dois coelhos foram mantidos no mesmo ambiente sob controle de temperatura, de atividades diárias e de alimentação. A eutanásia dos animais ocorreu dez dias após a intervenção e foram realizadas biópsias da cartilagem de cada joelho. As peças foram preparadas para análise em microscopia eletrônica (ME). RESULTADOS: Quatro preparados para ME foram obtidos, cada um correspondendo a um joelho. Os joelhos-PRP apresentaram as taxas de apoptose de 47,62% (50/105) e de 48,36% (59/122), respectivamente. Nos joelhos-SF as taxas de apoptose foram, respectivamente, 56,67% (17/30) e 70,40% (88/125). A diferença do índice de apoptose nos joelhos-PRP (48,02%) e nos joelhos-SF (67,74%) foi significante (p<0,001) e OR=0,439 (IC95%=0.287-0.673). CONCLUSÃO: A injeção intra-articular de PRP imediatamente ao trauma, reduz as taxas de apoptose (pós-traumática) de condrócitos de coelhos.

Platelet concentrate vs. saline in a rat patellar tendon healing model

PURPOSE

To evaluate single centrifuge platelet concentrate as additive for improved tendon healing. Platelet-rich plasma has been reported to improve tendon healing. Single centrifuge platelet concentration may increase platelet concentration enough to positively affect tendon healing. A single centrifuge process will lead to a blood product with increased platelet concentrations which, when added to a surgically created tendon injury, will improve tendon healing when compared with a saline control.

METHODS

Lewis rats had a surgical transection of the patellar tendon that was subsequently stabilized with a cerclage suture. Prior to skin closure, the tendon was saturated with either a concentrated platelet solution or saline. At 14 days, all animals were killed, and the extensor mechanism was isolated for testing. Biomechanical testing outputs included ultimate tensile load, stiffness, and energy absorbed.

RESULTS

Comparisons between the control group and the concentrated platelet group revealed no differences. A subgroup of the concentrated platelet group consisting of specimens in whom the concentration process was most successful showed significantly higher ultimate tensile load (P < 0.05) and energy absorbed to failure (P < 0.05) when compared to the control group.

CONCLUSION

When successful, single centrifuge platelet concentration yields a solution that improves tendon healing when compared with a saline control. Single-spin platelet concentration may yield a biologically active additive that may improve tendon healing, but more studies must be undertaken to ensure that adequate platelet concentration is possible.

Platelet lysate modulates MMP-2 and MMP-9 expression, matrix deposition and cell-to-matrix adhesion in keratinocytes and fibroblasts

Cell-matrix interactions are an essential element of wound healing, while platelet derivatives are used in clinical settings for the treatment of chronic wounds. We used a platelet lysate (PL), which had been previously shown to accelerate in vitro the wounding of HaCaT keratinocytes and fibroblasts (J Cell Mol Med, 13, 2009, 2030; Br J Dermatol, 159, 2008, 537), to study the modulation of MMP-2 and MMP-9 collagenase expression, collagen type I and III production and syndecan-4 expression and rearrangement in these cells. Zymography and Western blot analyses showed that exposure to 20% (v/v) PL for 24 h induced an apparently ERK1/2- and p38-dependent, NF-kappaB-independent, translational upregulation of MMP-9 in HaCaT, while HaCaT MMP-2 and fibroblast collagenases were almost unaffected. The use of in-cell ELISA showed that PL induced an increase in the collagen III production of fibroblasts. In-cell ELISA and immunofluorescence microscopy revealed an increase in the expression of syndecan-4 and its rearrangement to form focal adhesions in both cell types after PL exposure. Taken together, data indicate that PL promotes keratinocyte epithelialization and regulates fibroblast matrix deposition, thus providing a molecular basis for the ability of this platelet derivative to heal severe and problematic wounds without leading to heavy scarring and keloid formation.

The effect of platelet rich plasma combined with microfractures on the treatment of chondral defects: an experimental study in a sheep model

OBJECTIVE

To evaluate the effect of autologous platelet rich plasma (PRP) combined with microfractures on the treatment of chondral defects. The hypothesis of the study was that PRP can enhance cartilage repair after microfractures.

METHODS

A chronic full-thickness chondral lesion of the medial femoral condyle was performed in 15 sheep. Animals were divided into three groups, according to treatment: group 1: microfractures; group 2: microfractures+PRP and fibrin glue gel; group 3: microfractures+liquid-PRP injection. Animals were sacrificed at 6 months after treatment. Macroscopic appearance was evaluated according to International Cartilage Repair Society (ICRS) score; cartilage stiffness was analyzed with an electromechanical indenter (Artscan 200); histological appearance was scored according to a modified O'Driscoll score. Comparison between groups for each outcome was performed with Kruskal-Wallis test, and Tukey's test for pairwise comparisons.

RESULTS

Macroscopic ICRS score of group 2 was significantly better than those of the other groups, and score of group 1 was significantly lower than those of the other groups. Scores of group 1 and 3 were significantly lower than that of normal cartilage. Mean cartilage stiffness of groups 1 and 3 was significantly lower than that of normal cartilage. Histological total scores of group 2 and 3 were significantly better than that of group 1.

CONCLUSIONS

PRP showed a positive effect on cartilage repair and restoration after microfractures. The procedure was more effective when PRP was used as a gel in comparison with liquid intra-articular injection. Histological analysis revealed that none of experimental treatments produced hyaline cartilage.

Blood components for topical use in tissue regeneration: evaluation of corneal lesions treated with platelet lysate and considerations on repair mechanisms

BACKGROUND

The fields of application of topically administered platelet derivatives are numerous and increasing. The use of this blood component is based on the fact that it contains growth factors and proteins of the clotting system. Studies carried out so far have been aimed at identifying these substances, assaying their content in the various types of platelet concentrate used, determining the in vivo and in vitro mechanisms of action, and trying to standardise the production methods. However, much still remains to be discovered, not only about the growth factors, but also about all those cytokines and biochemical mediators that are involved in the processes of tissue regeneration.

METHODS

We studied the use of platelet lysate, obtained from platelet-rich plasma which had been frozen, for the treatment of corneal ulcers caused by neurotrophic keratitis and of epithelial and stromal loss following physical or chemical trauma. The platelet lysate was administered in the form of eye drops to patients who had not responded to conventional therapy and who were at risk of corneal scarring.

RESULTS

The results were satisfactory in terms of both tissue regeneration and healing time. The clinical follow-up showed a clear reduction in the time of regeneration of the damaged epithelium and stabilisation of the repair process. The epithelial defects disappeared completely in all the treated eyes within 6 to 32 days, with the time depending on the type of lesion and the severity of the damage.

CONCLUSIONS

The cornea reacts to damage by releasing numerous substances, including cytokines, growth factors, proteases and neuropeptides in order to restore its anatomical integrity. A change in the balance between inhibitory and stimulating substances can lead to the development of complications. Fast, correct re-epithelialisation is fundamental for the formation of new, transparent tissue. The use of non-gelified platelet-rich plasma was found to be effective in all cases with loss of epithelium, such as post-herpetic corneal ulcers or ulcers occurring following trauma or exposure to caustic substances.

Curative effect of autologous platelet-rich plasma on a large cutaneous lesion in a dog

A dorsal tail mass (1 x 1.2 cm) was observed on a 10-year-old castrated male, Shih-tzu dog. A biopsy of the mass was performed and diagnosed histopathologically as a follicular cyst. A necrotic lesion (2.5 x 3 cm) developed at the biopsy site 1 week after sampling and failed to respond to 2 weeks of normal saline cleansing and systemic antibiotic administration. Autologous platelet-rich plasma was applied to the lesion which gradually improved over a 4-week period possibly by a contribution to the secretion of growth hormone, which can accelerate tissue regeneration. This case report suggests that autologous PRP may be beneficial in the management of large skin defects or in delayed wound healing.