In vivo efficacy proof of concept of a large-size bioprinted dermo-epidermal substitute for permanent wound coverage.

Introduction: An autologous split-thickness skin graft (STSG) is a standard treatment for coverage of full-thickness skin defects. However, this technique has two major drawbacks: the use of general anesthesia for skin harvesting and scar sequelae on the donor site. In order to reduce morbidity associated with STSG harvesting, researchers have developed autologous dermo-epidermal substitutes (DESs) using cell culture, tissue engineering, and, more recently, bioprinting approaches. This study assessed the manufacturing reliability and in vivo efficacy of a large-size good manufacturing practice (GMP)-compatible bio-printed human DES, named Poieskin®, for acute wound healing treatment. Methods: Two batches (40 cm2 each) of Poieskin® were produced, and their reliability and homogeneity were assessed using histological scoring. Immunosuppressed mice received either samples of Poieskin® (n = 8) or human STSG (n = 8) immediately after longitudinal acute full-thickness excision of size 1 × 1.5 cm, applied on the skeletal muscle plane. The engraftment rate was assessed through standardized photographs on day 16 of the follow-up. Moreover, wound contraction, superficial vascularization, and local inflammation were evaluated via standardized photographs, laser Doppler imaging, and PET imaging, respectively. Histological analysis was finally performed after euthanasia. Results: Histological scoring reached 75% ± 8% and 73% ± 12%, respectively, displaying a robust and homogeneous construct. Engraftment was comparable for both groups: 91.8% (SD = 0.1152) for the Poieskin® group versus 100% (SD = 0) for the human STSG group. We did not record differences in either graft perfusion, PET imaging, or histological scoring on day 16. Conclusion: Poieskin® presents consistent bioengineering manufacturing characteristics to treat full-thickness cutaneous defects as an alternative to STSG in clinical applications. Manufacturing of Poieskin® is reliable and homogeneous, leading to a clinically satisfying rate of graft take compared to the reference human STSG in a mouse model. These results encourage the use of Poieskin® in phase I clinical trials as its manufacturing procedure is compatible with pharmaceutical guidelines.

Human nasal olfactory stem cells, purified as advanced therapy medicinal products, improve neuronal differentiation.

Background: Olfactory ecto-mesenchymal stem cells (OE-MSC) are mesenchymal stem cells derived from the lamina propria of the nasal mucosa. They display neurogenic and immunomodulatory properties and were shown to induce recovery in animal models of spinal cord trauma, hearing loss, Parkinsons's disease, amnesia, and peripheral nerve injury. As a step toward clinical practice, we sought to (i) devise a culture protocol that meets the requirements set by human health agencies and (ii) assess the efficacy of stem cells on neuron differentiation. Methods: Nasal olfactory mucosa biopsies from three donors were used to design and validate the good manufacturing process for purifying stem cells. All processes and procedures were performed by expert staff from the cell therapy laboratory of the public hospital of Marseille (AP-HM), according to aseptic handling manipulations. Premises, materials and air were kept clean at all times to avoid cross-contamination, accidents, or even fatalities. Purified stem cells were cultivated for 24 or 48 h and conditioned media were collected before being added to the culture medium of the neuroblastoma cell line Neuro2a. Results: Compared to the explant culture-based protocol, enzymatic digestion provides higher cell numbers more rapidly and is less prone to contamination. The use of platelet lysate in place of fetal calf serum is effective in promoting higher cell proliferation (the percentage of CFU-F progenitors is 15.5%), with the optimal percentage of platelet lysate being 10%. Cultured OE-MSCs do not show chromosomal rearrangement and, as expected, express the usual phenotypic markers of mesenchymal stem cells. When incorporated in standard culture medium, the conditioned medium of purified OE-MSCs promotes cell differentiation of Neuro2a neuroblastoma cells. Conclusion: We developed a safer and more efficient manufacturing process for clinical grade olfactory stem cells. With this protocol, human OE-MSCs will soon be used in a Phase I clinical based on their autologous transplantation in digital nerves with a neglected injury. However, further studies are required to unveil the underlying mechanisms of action.

Intra Articular Injection of Autologous Microfat and Platelets-Rich Plasma in the Treatment of Wrist Osteoarthritis: A Pilot Study.

No injection treatment has been proven to be effective in wrist osteoarthritis. When conservative measures fail, its management involves invasive surgery. Emergence of biotherapies based on adipose derived stem cells (ADSC) offers promising treatments for chondral degenerative diseases. Microfat (MF) and platelets-rich plasma (PRP) mixture, rich in growth factors and ADSC could be a minimally invasive injectable option in the treatment of wrist osteoarthritis. The aim of this uncontrolled prospective study was to evaluate the safety of a 4 mL autologous MF-PRP intra-articular injection, performed under local anesthesia. The secondary purpose was to describe the clinical and MRI results at 12 months of follow-up. Patients' data collected were: occurrence of adverse effects, Visual analog scale (VAS), Disabilities of the Arm, Shoulder and Hand score (DASH) and Patient-Rated Wrist Evaluation (PRWE) scores, wrist strength, wrist range of motion and 5-level satisfaction scale. No serious adverse event was recorded. A statistically significant decrease in pain, DASH, PRWE and force was observed at each follow-up. Our preliminary results suggest that intra-articular autologous MF and PRP injection may be a new therapeutic strategy for wrist osteoarthritis resistant to medical symptomatic treatment prior to surgical interventions.

Three-year outcome of local injection of autologous stromal vascular fraction cells and microfat in refractory perianal fistulas of Crohn's disease.

Perianal fistulas in Crohn's disease are frequent and disabling, with a major impact on patients' quality of life. Cell-based therapy using mesenchymal stem cells represents new hope for these patients, but long-term efficacy remains challenging. In a pilot study, including patients with refractory complex perianal fistulas, autologous adipose-derived stromal vascular fraction (ADSVF) combined with microfat achieved combined remission in 60% of cases, with a good safety profile at 1 year. The purpose of this study is to assess whether these results were maintained at longer term. The safety and efficacy data of the ten patients were evaluated retrospectively 3 years after injection on the basis of clinical and radiological data. MRI were analysed according to the MAGNIFI-CD score. No adverse event was attributed to the experimental stem-cell treatment. Combined remission was achieved in 7 patients (70%) and associated with a significant improvement in the MAGNIFI-CD MRI score. In conclusion, the safety and efficacy of ADSVF and microfat injection in Crohn's disease fistulas were maintained at 3 years, demonstrating that this innovative strategy is effective in producing a long-lasting healing effect. The ongoing multicentre randomized placebo-controlled trial (NCT04010526) will be helpful to define the place for this approach in the current therapeutic arsenal.

Adipose tissue-derived stromal vascular fraction for treating hands of patients with systemic sclerosis: a multicentre randomized trial Autologous AD-SVF versus placebo in systemic sclerosis.

OBJECTIVE: To assess the superiority of adipose tissue-derived stromal vascular fraction (AD-SVF) injection into the fingers vs placebo in reducing hand disability in systemic sclerosis (SSc) patients. METHODS: We performed a double-blind, multicentre, phase II trial from October 2015 to January 2018 in France. SSc patients with a Cochin Hand Function Scale (CHFS) ≥20/90 were randomized 1:1 to receive injection of AD-SVF or placebo. AD-SVF was obtained using the automated processing Celution 800/CRS system. The placebo was lactated Ringer's solution. The primary efficacy end point was the change of the CHFS score from baseline to 3 months. Secondary efficacy endpoints included the CHFS score at 6 months, hand function, vasculopathy, hand pain, skin fibrosis, sensitivity of the finger pulps, Scleroderma Health Assessment Questionnaire, patients and physician satisfaction, and safety. RESULTS: Forty patients were randomized. The AD-SVF and placebo groups were comparable for age, sex ratio, disease duration, skin fibrosis of the hands and main cause of hand disability. After 3 months' follow-up, hand function significantly improved in both groups with no between-group difference of CHFS (mean change of -9.2 [12.2] in the AD-SVF group vs -7.6 [13.2] in the placebo group). At 6 months, hand function improved in both groups. CONCLUSION: This study showed an improvement of hand function in both groups over time, with no superiority of the AD-SVF. Considering the limits of this trial, studies on a larger population of patients with homogeneous phenotype and hand handicap should be encouraged to accurately assess the benefit of AD-SVF therapy. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT02558543. Registered on September 24, 2015.

Inter-center comparison of good manufacturing practices-compliant stromal vascular fraction and proposal for release acceptance criteria: a review of 364 productions.

BACKGROUND: Even though the manufacturing processes of the stromal vascular fraction for clinical use are performed in compliance with the good manufacturing practices applying to advanced therapy medicinal products, specifications related to stromal vascular fraction quality remain poorly defined. We analyzed stromal vascular fraction clinical batches from two independent good manufacturing practices-compliant manufacturing facilities, the Swiss Stem Cell Foundation (SSCF) and Marseille University Hospitals (AP-HM), with the goal of defining appropriate and harmonized release acceptance criteria. METHODS: This retrospective analysis reviewed the biological characteristics of 364 batches of clinical-grade stromal vascular fraction. Collected data included cell viability, recovery yield, cell subset distribution of stromal vascular fraction, and microbiological quality. RESULTS: Stromal vascular fraction from SSCF cohort demonstrated a higher viability (89.33% ± 4.30%) and recovery yield (2.54 × 105 ± 1.22 × 105 viable nucleated cells (VNCs) per mL of adipose tissue) than stromal vascular fraction from AP-HM (84.20% ± 5.96% and 2.25 × 105 ± 1.11 × 105 VNCs per mL). AP-HM batches were significantly less contaminated (95.71% of sterile batches versus 74.15% for SSCF batches). The cell subset distribution was significantly different (higher proportion of endothelial cells and lower proportion of leukocytes and pericytes in SSCF cohort). CONCLUSIONS: Both centers agreed that a good manufacturing practices-compliant stromal vascular fraction batch should exert a viability equal or superior to 80%, a minimum recovery yield of 1.50 × 105 VNCs per mL of adipose tissue, a proportion of adipose-derived stromal cells at least equal to 20%, and a proportion of leukocytes under 50%. In addition, a multiparameter gating strategy for stromal vascular fraction analysis is proposed.

A Retrospective Analysis of Characteristic Features of Responders and Impaired Patients to a Single Injection of Pure Platelet-Rich Plasma in Knee Osteoarthritis.

(1) Background: The emergence of injectable "biologic" medication creates a new approach to treat osteoarthritis (OA). Among them, the use of intra-articular injection of PRP became widespread despite the absence of consensus regarding its optimal composition. The aim of this study was to retrospectively correlate an extensive biological characterization of injected PRP to the clinical responses of patients presenting knee OA. (2) Methods: This retrospective study included 75 patients with knee OA. Cartilage lesions were assessed using magnetic resonance imaging and the International Cartilage Regeneration Society (ICRS) classification. PRP extensive biological characterization was performed and patients' subjective symptoms were recorded before injection and 3 and 6 months after injection using the Knee injury and Osteoarthritis Outcome Score (KOOS). Responders were defined by an improvement of 10 points on KOOS. (3) Results: At 6 months, 63.0% of the patients were responders. Impairment was characterized by a significantly higher proportion of patients with three compartments altered at baseline MRI and receiving a significantly higher dose of platelets compared to responders. (4) Conclusions: Single injection of pure PRP resulted in significant clinical improvement in the management of knee OA. Both baseline MRI and PRP biological features may be predictive factors of the clinical response, highlighting that a better understanding of action mechanism of PRP is still required.

Intra-Articular Injection of Autologous Microfat and Platelet-Rich Plasma in the Treatment of Knee Osteoarthritis: A Double-Blind Randomized Comparative Study.

PURPOSE: To compare a single abdominal microfat (MF) injection mixed or not with platelet-rich plasma (PRP) Low Dose (LD) or High Dose (HD) in order to improve MRI parameters, alleviate pain and enhance functional capacity in knee osteoarthritis. METHODS: Patients with symptomatic grade 2 to 4 knee osteoarthritis according to the International Cartilage Repair Society MRI classification were selected. They were prospectively assessed at baseline and at 3 and 6 months of follow-up. The primary endpoint was change in the maximum of value of cartilage relaxation time in T2 mapping sequences (T2max) at 3 months. Secondary endpoints were MRI grade severity and joint space assessment, Western Ontario and McMaster Universities Arthritis Index score, pain evaluation, knee range of motion, and patients' satisfaction. Adverse events were also collected. The complete cell counts and growth factors content of injected products were assessed to analyze their potential relationship with MRI and clinical outcomes. RESULTS: Three groups of 10 patients received a single injection of 10 cc of a mix (1:1) containing MF-Saline, MF-PRP LD or MF-PRP HD. T2max did not change significantly over the time for any of the groups. All treatments significantly improved knee functional status and symptom relief at 3 and 6 months. All patients were responders in the MF/PRP HD at 3 months and significantly higher compared to MF/PRP LD. Half of the injected PRP in the MF/PRP LD group displayed red blood cell contamination of over 8%, which was correlated with an impairment of T2max. CONCLUSION: A single intra-articular injection of MF with or without PRP is safe and may offer a significant clinical improvement in patients with osteoarthritis. LEVEL OF EVIDENCE: 2; randomized double-blind comparative parallel-group trial (RCT No.: NCT04352075).

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

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

Development and Validation of a Fully GMP-Compliant Process for Manufacturing Stromal Vascular Fraction: A Cost-Effective Alternative to Automated Methods.

The therapeutic use of adipose-derived stromal vascular fraction (SVF) is expanding in multiple pathologies. Various processes have been proposed for manufacturing SVF but they must be revisited based on advanced therapy medicinal product (ATMP) regulations. We report here the development and validation of a fully good manufacturing practices (GMP)-compliant protocol for the isolation of SVF. Adipose tissue was collected from healthy volunteers undergoing lipoaspiration. The optimal conditions of collagenase digestion and washing were determined based on measurements of SVF cell viability, yield recovery, and cell subset distribution. Comparability of the SVF obtained using the newly developed manufacturing process (n = 6) and the Celution-based automated method (n = 33), used as a reference, was established using inter-donor analyses. Characteristics of SVF (n = 5) generated using both manufacturing protocols were analyzed for an intra-donor comparison. In addition, these comparisons also included the determination of colony-forming unit fibroblast frequency, in vitro angiogenic activity, and in vivo regenerative effects in a mouse ischemic cutaneous wound model. We successfully developed a process for the generation of SVF presenting higher cell viability and yield recovery compared to the Celution device-based protocol. Characteristics of the SVF including phenotype, capacity for angiogenesis, and wound-healing promotion attested to the comparability of the two manufacturing processes. We validated an optimized non-automated process that should allow for a GMP-compliant, more affordable, and reduced-cost strategy to exploit the potential of SVF-based regenerative therapies.

Feasibility of First Injection of Autologous Adipose Tissue-Derived Stromal Vascular Fraction in Human Scarred Vocal Folds: A Nonrandomized Controlled Trial.

Importance: Patients with scarred vocal folds, whether congenitally or after phonosurgery, often exhibit dysphonia that negatively affects daily life and is difficult to treat. The autologous adipose tissue-derived stromal vascular fraction (ADSVF) is a readily accessible source of cells with angiogenic, anti-inflammatory, immunomodulatory, and regenerative properties. Objective: To evaluate the feasibility and tolerability of local injections of autologous ADSVF in patients with scarred vocal folds. Design, Setting, and Participants: CELLCORDES (Innovative Treatment for Scarred Vocal Cords by Local Injection of Autologous Stromal Vascular Fraction) is a prospective, open-label, single-arm, single-center, nonrandomized controlled trial with a 12-month follow-up and patient enrollment from April 1, 2016, to June 30, 2017. Eight patients with severe dysphonia attributable to vocal fold scarring associated with a congenital malformation or resulting from microsurgical sequelae (voice handicap index score >60 of 120) completed the study. Data analysis was performed from September 1, 2018, to January 1, 2019. Interventions: Injection of ADSVF into 1 or 2 vocal folds. Main Outcomes and Measures: The primary outcomes were feasibility and the number and severity of adverse events associated with ADSVF-based therapy. The secondary outcomes were changes in vocal assessment, videolaryngostroboscopy, self-evaluation of dysphonia, and quality of life at 1, 6, and 12 months after cell therapy. Results: Seven women and 1 man (mean [SD] age, 44.6 [10.4] years) were enrolled in this study. Adverse events associated with liposuction and ADSVF injection occurred; most of them resolved spontaneously. One patient received minor treatment to drain local bruising, and another experienced a minor contour defect at the liposuction site. At 12 months, the voice handicap index score was improved in all patients, with a mean (SD) improvement from baseline of 40.1 (21.5) points. Seven patients (88%) were considered to be responders, defined as improvement by 18 points or more in the voice handicap index score (the minimum clinically important difference). Conclusions and Relevance: The findings suggest that autologous ADSVF injection in scarred vocal folds is feasible and tolerable. The findings require confirmation in a randomized clinical trial with a larger population. Trial Registration: ClinicalTrials.gov Identifier: NCT02622464.

A retrospective analysis of characteristic features of responder patients to autologous serum eye drops in routine care.

PURPOSE: Autologous serum eye drops (ASEDs) are used worldwide to treat dry eye disease (DED). However, the biological composition of ASEDs has not been well investigated, and effectiveness predictive factors remain to be identified. The main objective of this study was to compare the response of patients treated with ASEDs biologically characterized and used for DED routine care. METHODS: This retrospective observational study was conducted in a single university hospital, and included 50 patients (87 eyes) with DED refractory to conventional treatment and resulting from various etiologies with Ocular Surface Disease Index (OSDI) ≥ 20. Each patient used eight drops a day per treated eye with 20% diluted ASEDs. Undiluted serum extensive biological characterizations were performed, and symptoms were recorded before the initiation of ASEDs and closer to the sixth month of treatment. Responders were defined as presenting an improvement from baseline ≥14 points in OSDI and/or ≥1 grade in corneal fluorescence staining for all eyes treated. RESULTS: The OSDI and the Oxford scale were significantly reduced from 68.7 ±â€¯23.2 to 54.8 ±â€¯25.7 and 3.2 ±â€¯1.5 to 2.1 ±â€¯1.3 (p ≤ 0.0001), respectively. A total of 68% of the patients were responders. Nonresponding patients had significantly higher epidermal growth factor concentrations in the serum compared to responders (p = 0.017). CONCLUSIONS: ASED administration resulted in significant clinical improvement in the management of DED. Biological differences observed between responders and nonresponders suggested that a better understanding of the biological activity of ASEDs is still required.

Development of Autologous Platelet-Rich Plasma Mixed-Microfat as an Advanced Therapy Medicinal Product for Intra-Articular Injection of Radio-Carpal Osteoarthritis: From Validation Data to Preliminary Clinical Results.

Wrist osteoarthritis (OA) is one of the most common conditions encountered by hand surgeons with limited efficacy of non-surgical treatments. The purpose of this study is to describe the Platelet-Rich Plasma (PRP) mixed-microfat biological characteristics of an experimental Advanced Therapy Medicinal Product (ATMP) needed for clinical trial authorization and describe the clinical results obtained from our first three patients 12 months after treatment (NCT03164122). Biological characterization of microfat, PRP and mixture were analysed in vitro according to validated methods. Patients with stage four OA according to the Kellgren Lawrence classification, with failure to conservative treatment and a persistent daily painful condition >40 mm according to the visual analog scale (VAS) were treated. Microfat-PRP ATMP is a product with high platelet purity, conserved viability of stromal vascular fraction cells, chondrogenic differentiation capacity in vitro and high secretion of IL-1Ra anti-inflammatory cytokine. For patients, the only side effect was pain at the adipose tissue harvesting sites. Potential efficacy was observed with a pain decrease of over 50% (per VAS score) and the achievement of minimal clinically important differences for DASH and PRWE functional scores at one year in all three patients. Microfat-PRP ATMP presented a good safety profile after an injection in wrist OA. Efficacy trials are necessary to assess whether this innovative strategy could delay the necessity to perform non-conservative surgery.

Use of platelet-rich plasma in regenerative medicine: technical tools for correct quality control.

BACKGROUND/AIMS: Platelet-rich plasma (PRP) injections are used in sports medicine and have been the subject of increased clinical interest. However, there have been very few reports of the composition of initial whole blood and the final PRP product. The objective of this study was to provide technical tools to perform a correct characterisation of platelets, leucocytes and red blood cells (RBCs) from whole blood and PRP. METHODS: Blood and PRP were obtained from 26 healthy volunteers and prepared according to the varying parameters encountered within PRP process preparation and quantification (harvesting method, anticoagulant used, sampling method, counting method). Concentrations were measured at t=0, t=1, t=6 and t=24 hours. RESULTS: Sampling of blood in Eppendorf tubes significantly decreased platelet concentration over time, whereas sampling in Microvette EDTA-coated tube kept platelet concentration stable until 24 hours. A non-significant difference was observed in platelet counts in PRP with impedance (median (IQR): 521.8 G/L (505.3-524.7)) and fluorescence (591.5 G/L (581.5-595.8)) methods. Other studied parameters did not influence platelet concentrations in blood or PRP samples. Leucocytes and RBC counts were similar whatever the anticoagulant, sampling, harvesting and counting methods used for both blood and PRP samples. CONCLUSIONS: Systematic sampling of blood and PRP in EDTA-coated tubes for quality control is recommended. The use of a validated counter for PRP sample should also be taken into account.

First clinical case report of local microinjection of autologous fat and adipose-derived stromal vascular fraction for perianal fistula in Crohn's disease.

Mesenchymal stem cell therapy is a promising treatment for perianal Crohn's fistulas refractory to conventional therapy, which are an extremely morbid complication and a true therapeutic challenge. Autologous adipose-derived stromal vascular fraction (ADSVF) is an easily accessible source of cells with angiogenic, anti-inflammatory, immunomodulatory, and regenerative properties. Here, we describe a case involving a patient with severe perianal Crohn's fistulas refractory to the best medical and surgical practices who received local treatment with ADSVF and microfat. This patient was first examined under anesthesia with drainage via seton placement; 1 week later, on a single day, he underwent adipose tissue extraction, ADSVF and microfat preparation, and the local injection of 14 ml of microfat and approximately 20 million viable ADSVF cells into the soft tissue around the fistulas. No serious adverse events were observed. At the first endpoint at 12 weeks, the fistula had clinically healed with complete re-epithelialization of all external openings; no fistula tract was detected on magnetic resonance imaging, confirming this finding. This good clinical outcome was sustained at 48 weeks and was associated with a reduction in the severity of perianal disease and an improvement in quality of life. The current case highlights the therapeutic potential of a new cellular treatment for Crohn's patients with refractory perianal fistulas based on the innovative hypothesis that the combined action of ADSVF in association with the trophic characteristics of a microfat graft could be beneficial for this condition. TRIAL REGISTRATION: EudraCT number 201325, NCT02520843 . Registered on 5 August 2015.

Growth Factors Levels Determine Efficacy of Platelets Rich Plasma Injection in Knee Osteoarthritis: A Randomized Double Blind Noninferiority Trial Compared With Viscosupplementation.

PURPOSE: To assess the noninferiority of a single platelet-rich plasma (PRP) injection compared with hyaluronic acid (HA), to alleviate pain and enhance functional capacity in knee osteoarthritis, and identify biological characteristics of PRP that may affect their efficacy. METHODS: Fifty-four patients with symptomatic knee osteoarthritis received a single injection of either PRP (26 patients) or HA (28 patients). They were assessed at baseline and at 1, 3, and 6 months. The primary endpoint was the change in Western Ontario and McMaster Universities Arthritis Index (WOMAC) score at 3 months, and secondary endpoints were responders' rate (improvement of at least 5 points or 40% of WOMAC total score at 3 months) of pain evaluation and patient's subjective satisfaction. Cell counts and the contents of vascular endothelial growth factor (VEGF), platelet-derived growth factor-AB (PDGF-AB), transforming growth factor beta 1 (TGF-ß1) content of injected PRP were assessed to analyze their relationship with clinical outcome. RESULTS: Both treatments proved their improvement in knee functional status and symptom relief, with a significant decrease observed at 1 month on all scores except for pain VAS in PRP group and WOMAC function score in the HA group. No difference between groups regarding WOMAC and VAS scores was observed. A higher percentage of responders was observed in the PRP group (72.7%) than in the HA group (45.8%) without significance (P = .064). The quantity of injected PDGF-AB and TGF-ß1 correlated with the change in WOMAC scores at 3 months and was lower in responders than in nonresponders (P = .009 and P = .003, respectively). CONCLUSIONS: Current results indicated that a single injection of very pure PRP offers a significant clinical improvement in the management of knee osteoarthritis, equivalent to a single HA injection in this patient population. Moreover, a significant correlation between the doses of TGF-ß1 and PDGF-AB and the worsening of WOMAC score 3 months after the procedure was found. LEVEL OF EVIDENCE: Level II, randomized double blind controlled trial.