Applications of the regenerative capacity of platelets in modern medicine.

Platelets produce platelet growth factors such as PDGF, IGF-1, EGF-, HGF, TGFß, bFGF, and VEGF, which are crucial in regulating all stages of the wound healing process. The source of these substances is platelet-rich plasma (PRP). Over the past five decades, the interest and use of the regenerative properties of platelets have increased significantly in many different fields of medicine around the world. PRP and PRF plate preparations are used in: 1. Dentistry (they reduce bleeding, facilitate and accelerate soft tissue healing and bone regeneration - FGF 2, IGF-1, IGF-2, TGF-ß1, and PDGF); 2. Sports medicine - IGF-1, IGF-2, TGF-ß, VEGF, PDGF and bFGF, EGF); 3. dermatology and cosmetology (treatment of alopecia, hair reconstruction - FGF-7, HGF, acne scars, skin rejuvenation and regeneration, treatment of chronic and poorly healing wounds, burns, and acquired vitiligo); 4. Gynecology and reproductive medicine (treatment of infertility, erectile dysfunction - PDGF-ß, TGF-ß, IGF-1, in sexual dysfunction - PDGF, in vaginal atrophy); 5 Ophthalmology (in the healing of corneal epithelial wounds, in the treatment of dormant corneal ulcers, dry eye syndrome and the reconstruction of the corneal surface; 6. Neurology (regeneration of neurons, pain alleviation, and clinical symptoms - TGF-ß 1, IGF-1, PDGF, VEGF) and FGF). Platelet-rich plasma therapy is a very interesting alternative and complement to traditional methods of treatment. However, the potential for using platelets is still not fully understood. The composition of platelet-rich plasma depends on many factors that may affect its use's efficacy and clinical benefits. Further research is necessary to standardize PRP delivery's preparation procedures and methods for a specific disease entity or clinical case.

[Hearing dynamics in acute traumatic perforation of the tympanic membrane after application of blood plasma enriched with platelet growth factors]. / Regeneratsiya barabannoi pereponki i otsenka dinamiki slukha pri ostroi travmaticheskoi perforatsii barabannoi pereponki posle applikatsii plazmy krovi, obogashchennoi trombotsitarnymi faktorami rosta.

OBJECTIVE: The article considers the possibility of treating patients with acute traumatic perforation of the eardrum with a single application of blood plasma enriched with platelet-derived growth factors in the perforation area. As a result of the studies, it was found that the acceleration of its closure and the restoration of hearing. MATERIAL AND METHODS: The study included 43 patients with unilateral acute PBP of various etiologies (Table 1). Patients were divided into 2 groups - the main - 24 patients (10 men and 14 women), the average age - 30±9.7 years and the control - 19 patients (9 men and 10 women), the average age - 26.5±6.37 years. The compared groups did not reliably differ in age, gender, frequency and severity of hearing impairment. RESULTS: Analyzing the results, we can confidently talk about the beneficial effect of blood plasma enriched in platelet-derived growth factors on the speed, completeness of closure of traumatic perforation of the eardrum and the dynamics of restoration of auditory function. The use of blood plasma enriched with platelet growth factors led to a regular reduction in the time and increase in the frequency of cases of early closure of perforated eardrum, as well as improvement and restoration of auditory function according to the results of tonal threshold audiometry and otoacoustic emission in dynamics. CONCLUSION: Being generally available even in outpatient practice, the method of a single application of blood plasma enriched with platelet growth factors in the area of perforation of the tympanic membrane can significantly accelerate the healing process of the tympanic membrane, while improving the quality of life of the patient.

Stability of freeze-dried plasma rich in growth factors eye drops stored for 3 months at different temperature conditions.

PURPOSE: The purpose of this study was to analyze the biological content and activity of freeze-dried plasma rich in growth factors eye drops after their storage at 4°C and at room temperature for 3 months with respect to fresh samples (time 0). METHODS: Plasma rich in growth factors was obtained after blood centrifugation from three healthy donors. After platelet activation, the obtained plasma rich in growth factors eye drops were lyophilized alone or in combination with lyoprotectant (trehalose), then they were stored for 3 months at room temperature or at 4°C. Several growth factors were analyzed at each storage time and condition. Furthermore, the proliferative and migratory potential of freeze-dried plasma rich in growth factors eye drops kept for 3 months at different temperature conditions was evaluated on primary human keratocytes. RESULTS: The different growth factors analyzed maintained their levels at each time and storage condition. Freeze-dried plasma rich in growth factors eye drops stored at room temperature or 4°C for 3 months showed no significant differences on the proliferative activity of keratocytes in comparison with fresh samples. However, the number of migratory human keratocytes increased significantly after treatment with lyophilized plasma rich in growth factors eye drops kept for 3 months compared to those obtained at time 0. No significant differences were observed between the freeze-dried plasma rich in growth factors eye drops whether mixed or not with lyoprotectant. CONCLUSION: Freeze-dried plasma rich in growth factors eye drops preserve the main growth factors and their biological activity after storage at room temperature or 4°C for up to 3 months. Lyophilized plasma rich in growth factors eye drops conserve their biological features even without the use of lyoprotectants for at least 3 months.

Factores de crecimiento en el plasma: herramienta terapéutica en dermatología / Growth factors in plasma: therapeutic tool in dermatology

Las plaquetas contienen una gran cantidad de factores de crecimiento que participan en los procesos de cicatrización tisular. Entre ellos, el factor de crecimiento derivado de las plaquetas (PDGF), el factor de crecimiento transformante (TGF), el factor plaquetario 4 (PF4), la interleucina (IL)-1, el factor angiogénico derivado de las plaquetas (PDAF), el factor de crecimiento endotelial (VEGF), el factor de crecimiento epidérmico (EGF), el factor de crecimiento endotelial derivado de las plaquetas (PDEGF), el factor de crecimiento de células epiteliales (ECGF) y el factor de crecimiento similar a la insulina (IGF). El plasma rico en plaquetas (PRP) es un derivado sanguíneo concentrado de la sangre total con una alta concentración de plaquetas. Otro componente esencial del PRP son las proteínas que actúan a nivel de la adhesión celular (fibrina, fibronectina y vitronectina), que proporcionan el soporte estructural necesario para la migración celular y para la proliferación y crecimiento tridimensional de los tejidos sobre los que actúa. La fibrina es la forma activada del fibrinógeno, sustrato final de todas las reacciones de coagulación, se transforma en fibrina insoluble por acción de la trombina. El gel de fibrina polimerizado constituye la primera matriz cicatricial de las heridas. Tanto el plasma rico en plaquetas como las mallas de fibrina varían en la composición y concentración de factores de crecimiento, proteínas y citocinas. En este trabajo se revisan las características de estos productos biológicos, su aplicación en dermatología así como los principales requisitos para su preparación(AU)

Platelets contain a large amount of growth factors involved in the processes of tissue healing. Among them, plateletderived growth factor (PDGF), transforming growth factor (TGF), platelet factor 4 (PF4), interleukin (IL) -1, angiogenic factor derived from platelets (PDAF) , the endothelial growth factor (VEGF), the epidermal growth factor (EGF), the plateletderived endothelial growth factor (PDEGF), the epithelial cell growth factor (ECGF) and the Insulin like growth factor (IGF). Platelet-rich plasma (PRP) is a concentrated whole blood derivate with a high concentration of platelets. Another essential component of PRP are proteins acting on cell adhesion (fibrin, fibronectin and vitronectin), which provide the structural support necessary for cell migration and proliferation as well as three-dimensional growth of the tissues on which they act. Fibrin is the activated form of fibrinogen, the final substrate of all coagulation reactions. It is transformed into insoluble fibrin by the action of thrombin. The polymerized fibrin gel constitutes the first cicatricial matrix of wounds. Both plateletrich plasma and fibrin meshes vary in the composition and concentration of growth factors, proteins and cytokines. In this work we review the characteristics of these biological products, their application in dermatology as well as main requirements for their preparation(AU)

Prospective Randomized Evaluation of Local Injection of Allogeneic Growth Factors in Plantar Fasciitis.

BACKGROUND: The aim of this study was to evaluate the efficacy and safety of injection of allogeneic growth factors in patients with plantar fasciitis. METHODS: This study included 150 patients who were randomly divided into 2 equal groups; the patients were locally injected with allogeneic growth factors (GFs) (treatment group) or with saline 0.9% (control group). The patients were assessed using visual analog scale (VAS) and Foot Function Index-Revised short form (FFI-Rs) scores preinjection and 1, 3, 6, and 12 months postinjection. The patients were questioned about their satisfaction. Any adverse effects were recorded. RESULTS: At baseline, there was no significant difference between both groups regarding the mean VAS and FFI-Rs scores. At 3-month follow-up, the reduction in mean VAS score was 87% in the treatment group and 55% in the control group (P < .001), and the reduction in mean FFI-Rs score was 62% in the treatment group and 40% in the control group (P < .001). Treatment group and study visit were significant factors affecting both VAS and FFI-Rs scores. Overall, 92% were satisfied in the treatment group, and 78.2% in the control group. Postinjection pain occurred in 5 patients in the treatment group. CONCLUSION: This study provides Level I evidence regarding the efficacy and safety of allogeneic GF injection in patients with plantar fasciitis. However, additional studies are needed to evaluate their adverse effects, immunogenicity, and microbiological safety. LEVEL OF EVIDENCE: Level I, prospective randomized controlled case series.

Regenerative potential of platelets in patients with chronic kidney disease.

INTRODUCTION: Chronic kidney disease (CKD) is a systemic disease affecting many organs. Progression of renal failure aggravates ongoing inflammation and increases oxidative stress. In the final stage of CKD, it is necessary to use renal replacement therapy. A side effect of dialysis therapy is the synthesis of proinflammatory factors and increased oxidative stress, which activates platelets and immune cells. AIM OF THE STUDY: To determine the regenerative potential of platelets in patients with CKD based on the analysis of the relationships between substances with potential regenerative action, as well as analysis of the influence of the type of renal replacement therapy used on regeneration of platelets. MATERIALS AND METHODS: The study group consisted of 117 patients. Based on the type of therapy used, patients were divided into four groups: hemodialysis, peritoneal dialysis, kidney transplant patients, and conservative treatment (30, 30, 27, and 30 patients). The control group consisted of 30 healthy volunteers. The concentrations of IGF-1, TGF-ß, and PDGF-B in the blood serum were measured by ELISA methods. RESULTS: It was shown that renal replacement therapy significantly influences the concentration of platelet growth factors (IGF-1: p = 0.025 and PDGF-B: p = 0.012). There was a relationship between the type of renal replacement therapy and the duration of dialysis, and the concentration of IGF-1, PDGF-B (p < 0.00001, p < 0.001). CONCLUSIONS: The type of renal replacement therapy has a different effect on the concentration of platelet-derived growth factors IGF-1 and PDGF-B. PD patients had the highest concentrations of all growth factors, and this may be due to the presence of inflammation induced by dialysis-related advanced end-products of glycosylation (AGE).

Platelet-Rich Fibrin Scaffolds for Cartilage and Tendon Regenerative Medicine: From Bench to Bedside.

Nowadays, research in Tissue Engineering and Regenerative Medicine is focusing on the identification of instructive scaffolds to address the requirements of both clinicians and patients to achieve prompt and adequate healing in case of injury. Among biomaterials, hemocomponents, and in particular Platelet-rich Fibrin matrices, have aroused widespread interest, acting as delivery platforms for growth factors, cytokines and immune/stem-like cells for immunomodulation; their autologous origin and ready availability are also noteworthy aspects, as safety- and cost-related factors and practical aspects make it possible to shorten surgical interventions. In fact, several authors have focused on the use of Platelet-rich Fibrin in cartilage and tendon tissue engineering, reporting an increasing number of in vitro, pre-clinical and clinical studies. This narrative review attempts to compare the relevant advances in the field, with particular reference being made to the regenerative role of platelet-derived growth factors, as well as the main pre-clinical and clinical research on Platelet-rich Fibrin in chondrogenesis and tenogenesis, thereby providing a basis for critical revision of the topic.

[The use of blood plasma enriched with platelet growth factors during experimental perforation of the tympanic membrane]. / Primenenie plazmy krovi, obogashchennoi trombotsitarnymi faktorami rosta, pri éksperimental'noi perforatsii barabannoi pereponki.

OBJECTIVE: To study morphofunctional tissue changes during perforation of the tympanic membrane using blood plasma enriched with platelet growth factors in the experiment. MATERIAL AND METHODS: Examined 36 rats (72 tympanic membranes), which were divided into 2 groups, experimental (1st) and control (2nd). Injected blood plasma enriched with platelet-derived growth factors into the external auditory canal once by application after perforation of the tympanic membrane in the rats of the experimental group. Sacrificed rats on the 5th, 10th, 15th day after surgery (6 animals in each group at each stage). Evaluated the condition of the tympanic membrane otoscopically during the experiment. Evaluated the signs of acute otitis media, the presence of 'dry' perforation of the tympanic membrane (without signs of inflammation), and the closure of perforation of the tympanic membrane. RESULTS: In the experimental group, on the 5th day after the surgery, there were no signs of acute otitis media, closure of perforation of the tympanic membrane was identified in 4 cases, 'dry' perforation of the tympanic membrane (without signs of inflammation) was preserved in 8 cases. In the control group, on the 5th day after the surgery, the signs of acute otitis media were identified in 9 cases, cases of closure of the perforation of the tympanic membrane were not noted, 'dry' perforation of the tympanic membrane was preserved in 3 cases. In the 1st group, on the 10th day after surgery, the signs of acute otitis media were identified in 1 case, 'dry' perforation of the tympanic membrane was preserved in 1 case, closure of perforation of the tympanic membrane was identified in 10 cases. At the same time in the 2nd group, the signs of acute otitis media were identified in 6 cases, the 'dry' perforation of the tympanic membrane was preserved in 6 cases, there were no cases of closure of the perforation of the tympanic membrane. In the 1st group, on the 15th day after the surgery, there were no signs of acute otitis media, 'dry' perforation of the tympanic membrane was preserved in 1 case, closure of perforation of the tympanic membrane was identified in 11 cases. In the 2nd group, on the 15th day after surgery the signs of acute otitis media was identified in 1 case, 'dry' perforation of the tympanic membrane was preserved in 10 cases, the closure of perforation of the tympanic membrane was noted in 1 case. CONCLUSION: Preliminary results show a favorable effect of blood plasma enriched with platelet growth factors on the regeneration of the tympanic membrane under conditions of its traumatic perforation in the rat experiment, which is manifested in a decrease in the incidence of acute otitis media on the 5th day after perforation and in an increase in the incidence of closure of tympanic membrane perforation both on the 10th and 15th day, and in general in the experimental group.

Therapeutic implication of platelets in liver regeneration -hopes and hues.

INTRODUCTION: Mounting evidence highlights platelet involvement in liver regeneration via interaction with liver cells, growth factors release, and signaling contributions. Existing research suggests a compelling biological rationale for utilizing platelet biology, with the goal of improving liver function and accelerating its regenerative potential. Despite its expanding application in several clinical areas, the contribution of the platelet and its therapeutic implementation in liver regeneration so far has not yet fulfilled the initial high expectations. Areas covered: This review scrutinizes the progress, current updates, and discusses how recent understanding - particularly in the clinical implications of platelet-based therapy - may enable strategies to introduce and harness the therapeutic potential of the platelet during liver regeneration. Expert commentary: Several clinical and translational studies have facilitated a platform for the development of platelet-based therapy to enhance liver regeneration. While some of these therapies are effective to augment liver regeneration, the others have had some detrimental outcomes. The existing evidence represents a challenge for future projects that are focused on directly incorporating platelet-based therapies to induce liver regeneration.

Platelet-rich plasma-an 'Elixir' for treatment of alopecia: personal experience on 117 patients with review of literature.

Platelet-rich plasma (PRP) has emerged as a new treatment modality in regenerative plastic surgery and dermatology. PRP is a simple, cost-effective and feasible treatment option with high patient satisfaction for hair loss and can be regarded as a valuable adjuvant treatment modality for androgenic alopecia and other types of non-scarring alopecias. Authors have proposed a hair model termed "Golden anchorage with 'molecular locking' of ectodermal and mesenchymal components for survival and integrity of hair follicle (HF)" in this article. Golden anchorage comprises of bulge stem cells, ectodermal basement membrane and bulge portion of APM. PRP with its autologous supply of millions of growth factors works on 'Golden anchorage' along with keratinocytes (PDGF), dermal papilla (IGF and fibroblast growth factor), vasculature (VEGF and PDGF) and neural cells (Nerve Growth Factor) in a multipronged manner serving as an 'elixir' for hair growth and improving overall environment.

Factores de crecimiento aportados por el lisado plaquetario en el tratamiento tópico de úlceras posflebíticas / Platelet lysate-derived growth factors for topical treatment of postphlebitis ulcers

Introducción: los factores de crecimiento plaquetario son proteínas bioactivas que se sintetizan y almacenan en las plaquetas. Objetivo: evaluar la efectividad de los factores de crecimiento aportados por el lisado plaquetario alogénico en el tratamiento tópico de úlceras posflebíticas Métodos: se realizó un estudio cuasi-experimental con control simultáneo en la consulta de medicina regenerativa, Hospital General Docente "Comandante Pinares", entre enero de 2008 y diciembre de 2012. Se evaluaron 135 pacientes con el diagnóstico de úlceras posflebíticas con inadecuada respuesta al tratamiento convencional y ausencia de otras enfermedades de base que impidieran una respuesta a la terapia regenerativa. Los pacientes se dividieron en dos grupos: 90 recibieron tratamiento con la aplicación local del lisado plaquetario obtenido de las plaquetas alogénicas ABO compatibles y 45 mantuvieron el tratamiento convencional (grupo control). El tiempo de respuesta fue la característica distintiva para medir la eficacia entre ambos tratamientos. Resultados: predominó el sexo femenino y edad de más de 50 años. Los síntomas cardinales del síndrome posflebítico, estuvieron presentes en un mayor número de pacientes del grupo tratado con el lisado plaquetario, sin embargo, a los 30 días, se constató una mejoría de los mismos así como una disminución significativa del área promedio de las úlceras. En el grupo tratado con lisado, 86 pacientes remitieron sus síntomas en menos de seis semanas, frente a solo ocho en el mismo tiempo en el grupo convencional. Conclusiones: el uso de factores de crecimiento aportados por el lisado plaquetario alogénico fue efectivo en el tratamiento tópico de úlceras posflebíticas(AU)

Introduction: platelet-derived growth factors are bio-active proteins that are synthesized and stored in the platelets. Objective: to evaluate the effectiveness of allogenic platelet lysate-derived growth factors in the topical treatment of postphlebitis ulcers. Methods: a quasi-experimental study with simultaneous control was conducted from January 2008 through December 2012 in the regenerative medicine service of "Comandante Pinares" general teaching hospital located in San Cristobal, Artemisa province, Cuba. One hundred and thirty five patients with diagnosis of postphlebitis ulcers, inadequate response to the conventional treatment and absence of other illnesses that could hinder such response to regenerative therapy were evaluated. The patients were divided into two groups: 90 treated with local use of compatible ABO allogenic platelet-derived platelet lysate and 45 kept under the conventional treatment (control group). The reaction time was the distinctive characteristic to measure the effectiveness of both treatments. Results: females and over 50 years-old age predominated. The main symptoms of the posphlebitic syndrome were present in a high number of patients in the group treated with the platelet lysate. Thirty days later, these symptoms significantly improved and the average ulcer area dramatically decreased. There was observed symptoms remission in eighty six patients in less than six weeks in contrast with only eight in the conventional group during this period. Conclusions: the use of allogenic platelet lysate-derived growth factors was effective in the topical treatment of postphlebitis ulcers(AU)

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

BACKGROUND AND OBJECTIVES: Platelets are a source of numerous growth factors which facilitate repair and healing. Thus platelet rich plasma has been increasingly used as a treatment modality in the field of reconstructive surgeries for wound healing. This preliminary study was carried out to explore whether platelet growth factors from platelet rich plasma could be used for enhancement of split thickness skin graft survival. MATERIALS AND METHODS: Twenty patients (13 males and 7 females) requiring split thickness skin graft for various clinical reasons were enrolled in the study. Platelet rich plasma was collected by apheresis and frozen at -80° C. It was thawed at room temperature immediately before its intended application. PRP was applied only on one half of the wound, while another half served as control. Patient was followed for 6 weeks. The effect was assessed at first dressing in terms of graft uptake and subsequently as time taken for complete healing. RESULTS: There was 100% uptake of the graft in the area where platelet rich plasma was applied. In the control area, there was complete graft loss in 4 cases, partial loss in 7 cases and complete uptake in 9 cases. CONCLUSION: This study demonstrated promising results on application of PRP to split thickness skin grafts. Further randomized studies with greater sample size may be undertaken to establish platelet rich plasma as a validated treatment modality.

Autologous blood preparations rich in platelets, fibrin and growth factors.

OBJECTIVES: Bone regeneration is often needed prior to dental implant treatment due to the lack of adequate quantity and quality after infectious diseases. The greatest regenerative power was obtained with autologous tissue, primarily the bone alive, taken from the same site or adjacent sites, up to the use centrifugation of blood with the selection of the parts with the greatest potential regenerative. In fact, various techniques and technologies were chronologically successive to cope with an ever better preparation of these concentrates of blood. Our aim is to review these advances and discuss the ways in which platelet concentrates may provide such unexpected beneficial therapeutic effects. METHODS: The research has been carried out in the MEDLINE and Cochrane Central Register of Controlled Trials database by choosing keywords as "platelet rich plasma", "platelet rich fibrin", "platelet growth factors", and "bone regeneration" and "dentistry". RESULTS: Autologous platelet rich plasma is a safe and low cost procedure to deliver growth factors for bone and soft tissue healing. CONCLUSION: The great heterogeneity of clinical outcomes can be explained by the different PRP products with qualitative and quantitative difference among substance.

Platelet concentrates: past, present and future.

Platelets play a crucial role in hemostasis and wound healing, platelet growth factors are well known source of healing cytokines. Numerous techniques of autologous platelet concentrates have been developed and applied in oral and maxillofacial surgery. This review describes the evolution of the first and second generation of platelet concentrates (platelet rich plasma and platelet rich fibrin respectively) from their fore runner-fibrin sealants.

Platelet gel for the treatment of traumatic loss of finger substance.

BACKGROUND: Autologous or allogenic platelet gel is a blood component that exploits the effects of the cytokines contained in platelet α granules to stimulate repair processes. The properties of platelet gel were first tested on chronic ulcers to accelerate healing and later in orthopaedic, dental, vascular and cardiothoracic surgery. In our centre, we have been using platelet gel for 5 years, first for surgical patients with difficult wounds, then for orthopaedic patients undergoing osteosynthesis surgery and patients with ulcers not responding to traditional therapies. Subsequently we decided to extend the use of platelet gel also to amputations or traumatic loss of tissue of fingers. MATERIALS AND METHODS: In this article we present the results obtained over 5 years concerning 115 patients with finger amputations or wounds treated with platelet gel in our Service of Transfusion Medicine. Platelets were obtained fom allogeneic buffy coats (10 mL) and the gel was produced by adding thrombin to concentrated platelets. The decision to use homologous platelet gel was based on its limited cost, ease of preparation, almost unlimited availability, the fact that the number of platelets that can be collected is much higher than the therapeutic range and so able to replace the losses due to secondary medication, and last, but not least, it causes no discomfort to patients. The safety of the product was ensured by virology tests including molecular biology studies. RESULTS: The recovery of soft tissue in all patients ranged from 80 to 100%; the median time for this recovery was 3 weeks (range, 10 days - 6 weeks). Approximately 60% of the patients complained of local hypoaesthesia for some weeks; 30% of the patients developed hyperaesthesia, which resolved completely within 6-8 weeks from starting treatment. Loss of bone tissue represented an obstacle to total tissue recovery, but the aesthetic results were satisfactory in nearly all cases. CONCLUSION: All patients showed good compliance, both because of the low frequency of medications (at most, twice a week) and because of the painless platelet gel applications. The only negative aspect was abnormal nail growth in a case of distal partial amputation of a finger. In conclusion, we believe that platelet gel can be very useful in patients with traumatic or surgical loss of finger tissue, since it can resolve critical situations thus avoiding amputation of residual tissue and compromised joint function.

[Not Available].

BACKGROUND: The healing potential of platelet growth factors has generated interest in using Platelet-Rich Plasma (PRP) in ridge preservation procedures. A canine study was performed to determine if extraction sites treated with platelet-rich fibrin matrix (PRFM) exhibit enhanced healing compared to sites treated with non-viable materials. METHODS: Four dog's extraction sockets were treated individually with PRFM, PRFM and membrane, Demineralized Freeze-Dried Bone Allograft (DFDBA) and membrane, PRFM and DFDBA, and untreated control. Treatment sequencing permitted clinical and histologic evaluation of healing at 10 days, 2, 3, 6 and 12 weeks. RESULTS: Healing was more rapid in the PRFM and PRFM and membrane sites. By 3 weeks those sockets had osseous fill. Sites containing DFDBA had little new bone at 6 weeks. By 12 weeks those sockets had osseous fill but DFDBA particles were still noted in coronal areas. CONCLUSIONS: PRFM alone may be the best graft for ridge preservation procedures. ADVANTAGES: faster healing, and elimination of disadvantages involved in using barrier membranes.