Standardized Platelet-Rich Fibrin (PRF) from canine and feline origin: An analysis on its secretome pattern and architectural structure

Management of canine wounds using platelet-rich fibrin (PRF) biomaterial. A case series report

BACKGROUND

The increasing interest in platelet-based therapies has underwritten the development of novel veterinary regenerative treatments. The haemoderivative platelet-rich fibrin (PRF) comprises abundant concentrations of platelets and leucocytes, above the physiologic baseline, which are considered essential elements for wound regeneration, stimulating local angiogenesis, cellular migration, proliferation and differentiation, considered essential for skin repair.

OBJECTIVES

This study aimed to describe the treatment of eight dogs with naturally occurring cutaneous wounds, where autologous PRF therapy was applied, using a protocol developed by our group.

METHODS

Eight dogs, aged between 7-month and 9-year old, from different breeds and sexes, were enrolled in this study. Four of these wounds were clinically infected. In three cases, two PRF treatments were performed during the first week of treatment, followed by single weekly treatments from the second week onwards, until exophytic granulation tissues were present. In each case, the treatment was finalized only when complete wound closure was achieved. Wounds did not receive topical antiseptics, antibiotics or topical drugs to promote wound healing during the treatment.

RESULTS

PRF-grafting treatments were well tolerated in all treated wounds, inducing significant granulation tissue formation. PRF clots acted as a natural tissue filler, promoting epithelization and wound closure, without the requirement of topical antimicrobial/antiseptics application, or additional surgical debridement. Evident skin contraction was recorded in larger injuries and all the treatments resulted in vestigial aesthetic scars where hair growth was also observed.

CONCLUSIONS

PRF-therapy obtained promising results, as an alternative wound treatment, revealing a biological regenerative action, prompting the natural skin healing process.

Early tissue and healing responses after maxillary sinus augmentation using horizontal platelet rich fibrin bone blocks

BACKGROUND

The effects of horizontal platelet-rich fibrin (H-PRF) bone block on the healing and immune response during sinus augmentation have not been fully investigated histologically at early time points.

METHODS

Eighteenth male New Zealand white rabbits underwent bilateral sinus augmentation and were divided into two groups: deproteinized bovine bone mineral (DBBM) alone and H-PRF + DBBM (H-PRF bone block) group. Maxilla samples were collected at 3, 7 and 14 days post sinus augmentation procedures and analyzed using histological staining for the number of inflammatory cells, new blood vessels and evidence for early osteoclast bone turnover/remodeling. Furthermore, the effects of H-PRF bone blocks on the migration of osteoblasts and THP-1 macrophages were evaluated using a Transwell assay in vitro.

RESULTS

A higher number of immune cells were found in the H-PRF bone block group at 3 and 7 days post-surgery when compared to the DBBM alone group,most notably in the regions close to the mucosal lining and bone plates. Furthermore, a significantly greater number of new blood vessel formations and early signs of osteoclast development were found in the H-PRF bone block group at 14 days. The in vitro transwell assay further confirmed that culture medium from H-PRF bone block markedly promote the migration of osteoblasts and THP-1 macrophages.

CONCLUSIONS

The findings from this study have shown that H-PRF bone block is capable of increasing early immune cell infiltration leading to the acceleration of neovascularization and speeding the process of bone metabolism in vivo following maxillary sinus grafting with DBBM.

Peripheral mononuclear cells composition in platelet-rich fibrin in canines with chronic conditions

Platelet-rich fibrin (PRF) is a hot research topic because of its regenerative effect in humans. However, data reporting about its application in companion animals is lacking. The study aimed to supplement currently available data on PRF cell composition in canine patients by isolating peripheral blood mononuclear cells (PBMC), namely T cells, matured B cells, monocytes and macrophages, and adapting current protocols of cell flow cytometry for PRF analysis. The canine patient population was divided into three subgroups: animals with periodontitis only, animals with neoplasia and periodontitis, and healthy controls. Individual clinical parameters of the patients and evaluation of the wound healing quality were included in the research. In the present study, canine PRF cell composition was analyzed for the first-time using cell flow cytometry protocol. A higher proportion of PBMC cells related to wound healing (CD3+, CD3+ CD4+ CD8-, CD14+) were found in the PRF of control, periodontitis and neoplasia groups compared to the respective blood samples, which implies a positive outcome associated with clinical PRF usage in canine patients. Proportions of monocytes and macrophages were higher in PRF samples compared to the blood of healthy patients and periodontitis-affected patients. However, inflammatory and neoplastic processes do not affect the distribution of PBMC.

In Vitro Assessment of Lyophilized Advanced Platelet-Rich Fibrin from Dogs in Promotion of Growth Factor Release and Wound Healing

Advanced platelet-rich fibrin (A-PRF) induces more proliferation and migration of fibroblasts compared with standard PRF, but it being freshly prepared prior to it being applied is necessary. Therefore, this study aimed to determine the effect of lyophilized A-PRF on growth factor release and cell biological activity. Blood samples were collected from six dogs and processed for fresh and lyophilized A-PRF. The growth factors released included transforming growth factor beta-1 (TGF-β1), vascular endothelial growth factor-A (VEGFA), and platelet-derived growth factor-BB (PDGF-BB), and the fibroblast proliferation as well as wound closure enhancement of both products were compared. The results showed that TGF-β1, PDGF-BB, and VEGFA were continually released from lyophilized A-PRF for over 72 h. Lyophilized A-PRF released significantly more accumulated VEGEA and a tendency to release more TGF-β1 at 72 h as well as VEGFA at 24 h and 72 h than fresh A-PRF. Moreover, lyophilized A-PRF increased fibroblast proliferation and induced a significantly faster wound closure than the control, while no significant difference between fresh and lyophilized A-PRF was found. In conclusion, the lyophilization of canine A-PRF can preserve the release of growth factors and has similar biological activities to a fresh preparation. This encourages the substitution of lyophilized A-PRF instead of fresh A-PRF in regenerative treatments in which the stability of the product is concerned.

Production Protocol Standardisation, Macroscopic and Histological Evaluation, and Growth Factor Quantification of Canine Leukocyte-and Platelet-Rich Fibrin Membranes

Leukocyte-Platelet-Rich Fibrin (L-PRF) is a second generation of platelet concentrates; it was widely used, as an autologous platelet-based wound sealant and hemostatic agent in surgical wound healing. L-PRF clot or membrane is a solid fibrin-based biomaterial, with a specific 3D distribution of the leukocytes and platelet aggregates. This biological scaffold releases growth factors (i.e., TGF- β1, PDGF-AB, VEGF) and matrix proteins (fibronectin, vitronectin and thrombospondin-1) during the healing process after the application. To the Authors' knowledge both in human and veterinary medicine a single standardised protocol was not reported. This prospective study aimed to apply Crisci's L-PRF protocol (which is characterised by 30” of acceleration, 2' at 2,700 rpm, 4' at 2,400 rpm, 3' at 3,000 rpm, and 36” of deceleration and arrest) sin canine species, evaluate macroscopically and histologically the L-PRF membranes obtained by using Wound Box to standardise the L-PRF protocol in dogs and to evaluate the clinical feasibility of using L-PRF membranes by quantitative in vitro analysis of growth factors over 7 days. One hundred twenty-eight dogs in good general condition with no history of recent NSAIDs intake (15 days of washout) and/or any medication or disease related to coagulation process met inclusion criteria and therefore were enrolled. We obtained 172 membrane L-PRF membranes by 86 dogs: half of them underwent macroscopic and histological analysis, the other 86 underwent ELISA analysis. The Wound Box gave a membrane of mean (±SD) length (cm), width (cm) and weight (g) of 1.97 (±0.89), 0.95 (±0.36), 0.46 (±0.20) respectively. Histology analysis confirmed a well-defined histoarchitecture with five layers reproducing density and distribution of blood cells in this biomaterial. Finally, the ELISA assay performed with 22 L-PRF membranes showed a peak in growth factors at 6 h after membrane production, followed by a decrease in release at 24 and 72 h and a second peak in release at 168 h after production. Statistical analysis of demographic variables (age, sex, and body condition score BCS) and the average of growth factors determined by the ELISA assay did not reveal statistical significance, except for the BCS factor compared with the production of VEGF. Our data confirm the effectiveness of this protocol and of Wound Box to produce L-PRF membranes in dogs.

Evaluation of a Standardized Protocol for Plasma Rich in Growth Factors Obtention in Cats: A Prospective Study

Introduction

Platelet-rich plasma (PRP) is an autologous plasma with platelet (PLT) concentration above that of whole blood (WB). PLTs contain growth factors (GFs) that promote tissular repair.

Objectives

To determine and compare the concentrations of PLT, red blood cells (RBC) and white blood cells (WBC) between WB samples, PRP and platelet poor plasma (PPP) samples; and to analyze the concentrations of platelet-derived growth factor BB (PDGF-BB) and transforming growth factor β1 (TGF-β1) in the PRP and PPP of healthy adult cats using a standardized protocol with PRGF®-Endoret® characteristics.

Material and Methods

WB was collected from 30 cats. PRP was obtained following three centrifugation protocols using PRGF®-Endoret® technology: 255, 260, and 265 g for 10 min each. The cellular components, RBC, WBC, PLT, and the concentrations of PDGF-BB and TGF-β1 in the PRP and PPP fractions were determined for each protocol.

Results

PLTs in the PRP fraction were statistically higher than WB, with no statistical differences between PPP and WB. In PRP fraction, PLT concentration was increased 1.4 times on average at 255 g; 1.3 times at 260 g and, 1.5 times at 265 g without statistical differences among them. The mean platelet volume (MPV) was significantly higher in WB compared to PRP and PPP fractions without significant differences between protocols. Compared to WB, the number of RBCs and WBCs was reduced by 99% and by more than 95% in PRP and PPP respectively, without significant differences between protocols. PDGF-BB concentrations were statistically higher in PRP than in PPP fractions, however, TGF-ß1 concentrations did not vary between fractions at 260 g. Comparing the three protocols within PRP and PPP fractions, no differences in PDGF-BB and TGF-ß1 concentrations were observed.

Clinical Relevance

The study shows scientific evidence regarding the obtention of PRP in cats using the PRGF®-Endoret® technology for the quantification of PDGF-BB and TGF-ß1. At 265 g for 10 min, PLT concentration was increased 1.5 times with unnoticeable erythrocytes and leukocytes in the samples. These results clearly show that the PRGF®-Endoret® methodology is suitable to obtain PRP in cats. Further studies are needed to determine the clinical efficacy of the obtained PGRF in the treatment of different pathologies in cats.

Canine-Origin Platelet-Rich Fibrin as an Effective Biomaterial for Wound Healing in Domestic Cats: A Preliminary Study

Platelet-rich fibrin (PRF) is a recent platelet-based biomaterial, poised as an innovative regenerative strategy for the treatment of wounds from different etiologies. PRF is defined as a biodegradable scaffold containing elevated amounts of platelets and leukocytes having the capability to release high concentrations of bioactive structural proteins and acting as a temporal release healing hemoderivative. This study aimed to evaluate the performance of canine-origin PRF, obtained from blood of screened donors, as a regenerative biomaterial suitable for the treatment of critical wounds in felines. Four short-hair felines with naturally occurring wounds were enrolled in this study. Three of the wounds were considered infected. Each PRF treatment was the result of the grafting of newly produced PRFs at the recipient area. The PRF treatment was initially performed two to three times per week, followed by single weekly treatments. The study was finalized when complete wound closure was achieved. No topical antimicrobial/antiseptic treatment was applied. The present research demonstrated that xenogenic PRFs significantly induced healthy vascularized granulation tissue in lesions with soft tissue deficit, also prompting the epithelization at the injured site. No rejection, necrosis, or infection signs were recorded. Additionally, PRF-therapy was revealed to be a biological cost-effective treatment, accelerating the wound healing process.