Treatment of chronic venous leg ulcers by platelet gel

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 Fibrin Lysate Can Ameliorate Dysfunction of Chronically UVA-Irradiated Human Dermal Fibroblasts

To determine whether platelet-rich fibrin lysate (PRF-L) could restore the function of chronically ultraviolet-A (UVA)-irradiated human dermal fibroblasts (HDFs), we isolated and sub-cultured HDFs from six different human foreskins. HDFs were divided into two groups: those that received chronic UVA irradiation (total dosages of 10 J cm⁻²) and those that were not irradiated. We compared the proliferation rates, collagen deposition, and migration rates between the groups and between chronically UVA-irradiated HDFs in control and PRF-L-treated media. Our experiment showed that chronic UVA irradiation significantly decreased (p<0.05) the proliferation rates, migration rates, and collagen deposition of HDFs, compared to controls. Compared to control media, chronically UVA-irradiated HDFs in 50% PRF-L had significantly increased proliferation rates, migration rates, and collagen deposition (p<0.05), and the migration rates and collagen deposition of chronically UVA-irradiated HDFs in 50% PRF-L were equal to those of normal fibroblasts. Based on this experiment, we concluded that PRF-L is a good candidate material for treating UVA-induced photoaging of skin, although the best method for its clinical application remains to be determined.

Determining the Effect of Preparation and Storage: An Effort to Streamline Platelet Components as a Source of Growth Factors for Clinical Application

BACKGROUND

In the present study, different methods for preparation of platelet-rich plasma (PRP) are investigated in order to standardize the component in terms of growth factor content. The effects of concentration technique and storage duration are also analyzed.

METHODS

PRP was collected from 40 donors by plateletpheresis as well as by the buffy coat and tube method. Concentration of growth factors was performed using double freeze thaw- and CaCl2-induced degranulation techniques. Growth factor estimation was performed using ELISA.

RESULTS

The levels of growth factors were highest in PRP from buffy coat, moderately lower in plasma gained by plateletpheresis and lowest in that obtained by the tube method. Mean levels of platelet-derived growth factors (PDGF) AB and BB are significantly higher when CaCl2 was used for concentrating the growth factors. The mean levels of transforming growth factor β1 and insulin-like growth factor I were higher when applying the double freeze thaw technique. There was a substantial decline in the levels of growth factors during storage.

CONCLUSION

The buffy coat method is suitable as preparation method for PRP in most settings. The double freeze thaw technique is better suited as concentration technique as it causes lysis of both platelets and white blood cells for releasing growth factors and is easier to perform. Growth factors are not stable in plasma, thus PRP should be frozen immediately after preparation.

Treatment of life-threatening wounds with a combination of allogenic platelet-rich plasma, fibrin glue and collagen matrix, and a literature review

Currently there is no ideal procedure for the treatment of recalcitrant ulcers that are unresponsive to the majority of common treatments. However, several novel approaches have been proposed, including bone marrow stem cells, platelets, fibrin glue and collagen matrix. For the first approach treatment of a chronic wound, a non-invasive method is highly desirable. The present study was undertaken with the aim of evaluating the effect of a combination of platelets, fibrin glue and collagen matrix (PFC) in one treatment. A total of ten patients with aggressive, refractory, life-threatening wounds were recruited for the study and their treatment effects were evaluated. Initially, the ulcers were extensively debrided, measured and photographed at weekly intervals. The PFC combination was applied topically to the wound every two days. Following treatment, the wound was completely closed in nine patients and was markedly reduced in the other patient. The mean 100% healing time for the nine patients was 11.3±5.22 weeks. There was no evidence of local or systemic complications or any abnormal tissue formation, keloid or hypertrophic scarring. Therefore, the results of the present study indicate that in the first approach, the combination of PFC components may be used safely in order to synergize the effect of chronic wound healing.

Platelet-rich plasma: applications in dermatology

In recent years, the use of platelet-rich plasma has increased notably in a range of diseases and settings. Uses of these products now go beyond skin rejuvenation therapy in patients with facial ageing. Good outcomes for other dermatological indications such as skin ulcers and, more recently, alopecia have been reported in case series and controlled studies. However, these indications are not currently included in the labeling given that stronger scientific evidence is required to support their real benefits. With the increased use of these products, dermatologists need to become familiar with the underlying biological principles and able to critically assess the quality and outcomes of the studies of these products in different skin diseases.

Analyzing the effects of platelet gel on knee osteoarthritis in the rat model

Platelet gel (PG) includes concentrated dose of growth factors which plays role in physiological processes of healing. The goal of this study is to evaluate repairing effects of intra-articular injection of PG use in a rat model of knee osteoarthritis (OA). A total of 20 rats were randomly distributed into a PG group and a control group. Both the groups were induced OA in knee joints with intra-articular formaline injection. The rats in the PG group and the control group were injected in the knee joint with PG and 0.9% NaCl solution, respectively. Two weeks after last injections, all rats were sacrificed by ether asphyxiation. Tissue samples were obtained from the knee joints and were examined histopathologically. No statistically significant differences were found between the groups regarding cartilage healing (P > .05). We were unable to determine any beneficial or harmful effects of PG on joint cartilage healing in OA.

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 gel in the treatment of severe scleroderma skin ulcers

Systemic sclerosis (SSc) is characterized by microvascular damage and fibrosis of the skin and internal organs. Non-healing skin ulcers, mainly non-venous leg ulcers, represent one of the most challenging complications. Platelet gel (PG) is a hemocomponent containing numerous growth factors, potentially useful for tissue reparation. This pilot open study aimed to evaluate the effect of PG in 12 SSc patients with skin ulcers resistant to conventional therapies from at least 6 months. PG was applied in the wound bed twice weekly for 2 weeks, then once a week for 12 weeks; in all cases, the ongoing treatments remained unchanged at the time of PG applications. Skin ulcers were evaluated at 0, 12 and 24 weeks; the patient's quality of life was also evaluated using the visual analogical scale (VAS) and the health assessment questionnaire (HAQ). During the 6-month follow-up, the skin ulcers consistently improved in 10/12 patients, with complete healing in 4. At the last evaluation, wound size reduced from 23.4 ± 14.9 SD to 2.3 ± 2.2 SD cm(2) (p < 0.0001). Patient's quality of life markedly improved: VAS decreased from 87.08 ± 13.5 to 57.9 ± 12.6; p < 0.0001 and HAQ from 0.73 ± 0.43 to 0.57 ± 0.22; p < 0.0001. PG may represent a novel therapeutic option for SSc skin ulcers refractory to conventional treatments.

Effect of platelet rich plasma gel in a physiologically relevant platelet concentration on wounds in persons with spinal cord injury

The objective of the study was to investigate the use of a 1·3 times normal platelet concentration platelet-rich plasma (PRP) gel to move chronic wounds towards healing in persons with spinal cord injury (SCI). The study design was a case series of 20 persons with SCI with non healing wounds. The outcome measures were, in wound area, volume, undermining and sinus tracts/tunnels (ST/Ts), calculated average, (i) percent of change from baseline, (ii) change per day from baseline, (iii) number of treatments and (iv) number of weeks. In a mean of 4·0, after treatments over 3·4 weeks, the wounds closed on an average of 47·9% in area and 56·0% in volume. Undermining closed on an average of 31·4% using 3·5 treatments over 2·6 weeks. ST/Ts closed on an average of 26·1% after 2·3 treatments over 1·5 weeks. Clinical relevance by percent of positive responders and their response: in area, 90·0% of the subjects responded positively, the average reduction was 53·8%. In volume, 90·0% responded, with an average reduction of 67·3%. Of four subjects with undermining, 75% closed 47·0% on average. Of the three with ST/Ts, 100% closed 26·1% on average. Average haemoglobin and haematocrit levels were below normal. To conclude, 1·3× PRP gel appears to progress chronic, non healing wounds in SCI patients into the granulation phase of healing quickly. Review of the literature shows these results may not be applied to all PRP preparations.

Platelet gel in the treatment of cutaneous ulcers: the experience of the Immunohaematology and Transfusion Centre of Parma

BACKGROUND

Platelet gel is being ever more frequently used to promote healing of cutaneous ulcers. However, the factors that determine the often variable clinical outcome of this procedure are still incompletely understood.

AIMS

The aims of this study were to demonstrate that platelet gel, even when obtained under strictly controlled conditions, produces highly variable outcomes in patients with cutaneous ulcers and to propose a method for in vitro standardisation of the biological properties of platelet gel. MATERIAL AND METHODS.: Patients were enrolled on the basis of a pre-defined protocol. Platelet concentrate was produced with standard methods, with a variability in platelet count among the different samples of less than 10%. The platelet gel for clinical use was obtained, under strictly standardized conditions, by adding thrombin and calcium gluconate to the concentrates. For in vitro studies, platelet gel, obtained from platelet-rich plasma from four donors, was frozen and thawed twice so as to increase gel contraction. The supernatant was used to modify cell proliferation, protein synthesis, and the expression of selected genes in cultures of human diploid fibroblasts.

RESULTS

Seventeen patients (aged 44-78 years) with ulcers (4 diabetic, 11 vascular, 1 post-traumatic, 1 decubitus) were treated with platelet gel (4 autologous, 13 homologous). Complete re-epithelialisation of four ulcers (1 diabetic, 1 post-traumatic, 2 vascular) was obtained after applications of platelet gel (2 autologous, 2 homologous); in 11 other cases there was a greater than 50% reduction in the size of the ulcer. Two patients had no benefit. The supernatant of the platelet gel was able to promote dose-dependent proliferation and changes in gene expression as well as in metabolic activities related to protein synthesis.

CONCLUSIONS

Although the use of platelet gel in the treatment of cutaneous ulcers is increasing, and conditions for its production are better standardised, very considerable variability of clinical outcomes is still observed, even within single centres, suggesting that there are differences in biological properties of platelet concentrates from individual patients which cannot be readily controlled with current techniques. The biological effects of the platelet gel supernatant described in this article may provide the basis for a simple biological validation of platelet preparations before their clinical use, so as to reduce this potentially important source of variability.

Serotonin receptors in rat jugular vein: presence and involvement in the contraction

Serotonin (5-hydroxytryptamine; 5-HT) is released during platelet aggregation, a phenomenon commonly observed in blood clot formation and venous diseases. Once released, 5-HT can interact with its receptors in the peripheral vasculature to modify vascular tone. The goal of this study was to perform a detailed pharmacological characterization of the 5-HT receptors involved in the contractile response of the rat jugular vein (RJV) using recently developed drugs with greater selectivity toward 5-HT receptor subtypes. We hypothesized that, as for other blood vessels, the 5-HT(1B/1D) and 5-HT(2B) receptor subtypes mediate contraction in RJV alongside the 5-HT(2A) receptor subtype. Endothelium-intact RJV rings were set up in an isolated organ bath for isometric tension recordings, and contractile concentration-effect curves were obtained for 13 distinct serotonergic receptor agonists. Surprisingly, the 5-HT(1A) and the mixed 5-HT(1A/1B) receptor agonists (+/-)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene (8-OH-DPAT) and 5-methoxy-3 (1,2,3,6-tetrahydropyridin-4-yl) (1H indole) (RU24969) caused contractions that were antagonized by the 5-HT(1A) receptor antagonist [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide (WAY100135). The contractile curve to 5-HT was shifted to the right by WAY100135, 3-[2-[4-(4-fluoro benzoyl)-piperidin-1-yl]ethyl]-1H-quinazoline-2,4-dione (ketanserin; 5-HT(2A/C) receptor antagonist), and 1-(2-chloro-3,4-dimethoxybenzyl)-6-methyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole hydrochloride (LY266097; 5-HT(2B) receptor antagonist). Ketanserin also caused rightward shifts of the contractile curves to 8-OH-DPAT, RU24969, and the 5-HT(2B) receptor agonist (alpha-methyl-5-(2-thienylmethoxy)-1H-indole-3-ethanamine) (BW723C86). Agonists for 5-HT(1B/1D/1F), 5-HT(3), 5-HT(6), and 5-HT(7) receptors were inactive. In real-time polymerase chain reaction experiments that have never been performed in this tissue previously, we observed mRNA expression for the 5-HT(2A), 5-HT(2B), and 5-HT(7) receptors, whereas no significant mRNA expression was found for 5-HT(1A), 5-HT(1B), and 5-HT(1D) receptors. These results support the 5-HT(2A) receptor as the main subtype targeted by 5-HT to contract the RJV.