Evaluation of Platelet-Rich Plasma and Neutrophil Antimicrobial Extract as Two Autologous Blood-Derived Agents

A systematic review and meta-analysis of the efficacy of platelet-rich plasma products for treatment of equine joint disease

BACKGROUND

Equine joint disease including septic arthritis (SA) and osteoarthritis (OA) is a critical cause of equine lameness. Platelet-rich plasma (PRP) is one of the most popular regenerative therapies to treat equine OA, even SA, but the evidence in support of the treatment is conflicting.

OBJECTIVES

The aim of the study was to systematically review the current evidence on PRP products used for SA and OA, as well as the efficacy of PRP products as treatment for OA on the basis of a meta-analysis of the available literature.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic search of relevant databases (PubMed, Web of Science, Scopus) was performed to identify studies published from 2013 to 2023, in accordance with the PRISMA guidelines. Randomised controlled trials, non-randomised trials and controlled laboratory studies that used at least one type of PRP products were included. Dichotomous outcomes were presented using odds ratios (ORs) and 95% confidence intervals (95% CIs).

RESULTS

A total of 21 publications were identified in the systematic review and 5 of them in the meta-analysis. These publications involved various types of PRP products and reported different outcomes. Although most of the studies were associated with a high risk of bias, the overall estimated effect was consistent with a significant improvement in the PRP products treatment group compared with the control group (OR: 15.32; 95% CI: 3.00-78.15; p < 0.05). There was a significant improvement in clinical performance outcomes between the groups (OR: 36.64; 95% CI: 3.69-364.30; p < 0.05).

CONCLUSION

PRP products as intra-articular treatment are likely efficacious for treatment of equine OA and have potential for treating SA. These conclusions might be affected by the limited number of randomised controlled studies and high variability of different types of PRP products. To better evaluate the efficacy of PRP, a widely recognised classification system and the utilisation of randomised, blinded, equivalency or non-inferiority trials are required.

Prospects and Applications of Natural Blood-Derived Products in Regenerative Medicine

Currently, there are a number of therapeutic schemes used for the treatment of various types of musculoskeletal disorders. However, despite the use of new treatment options, therapeutic failure remains common due to impaired and delayed healing, or implant rejection. Faced with this challenge, in recent years regenerative medicine started looking for alternative solutions that could additionally support tissue regeneration. This review aims to outline the functions and possible clinical applications of, and future hopes associated with, using autologous or heterologous products such as antimicrobial peptides (AMPs), microvesicles (MVs), and neutrophil degranulation products (DGP) obtained from circulating neutrophils. Moreover, different interactions between neutrophils and platelets are described. Certain products released from neutrophils are critical for interactions between different immune cells to ensure adequate tissue repair. By acting directly and indirectly on host cells, these neutrophil-derived products can modulate the body’s inflammatory responses in various ways. The development of new formulations based on these products and their clinically proven success would give hope for significant progress in regenerative therapy in human and veterinary medicine.

The Effect of Neutrophil-Derived Products on the Function of Leukocytes Obtained after Titanium Implantation in the Ovine Model

Simple Summary

Titanium is one of the most commonly used biomaterials for implantation as a part of the orthopedic procedures. However, this biomaterial can cause an excessive inflammatory response, even leading to rejection of the implant. Therefore, the aim of our study was to assess the overall organism response after insertion of Ti implant and the activity of neutrophils and monocyte-derived macrophages (MDM), to evaluate the possible negative effect of this biomaterial on the host cells. Our study revealed that insertion of the Ti implant did not evoke systemic inflammatory response or activation of leukocytes. Additionally, we evaluated the activity of neutrophils and MDM after stimulation with autologous neutrophil products, namely, antimicrobial neutrophil extract and neutrophil degranulation product as two potential regulators of inflammatory response. Antimicrobial neutrophil extract appeared to be a factor causing the decrease of secretory neutrophil response and polarization of MDM towards pro-resolving phenotype, whereas the neutrophil degranulation product acted as pro-inflammatory.

Abstract

Titanium (Ti) is currently the most common biomaterial used for orthopedic implants; however, these implants may cause deleterious immune response. To investigate the possible mechanisms involved in excessive inflammation, we assessed the activity of neutrophils and monocyte-derived macrophages (MDMs) during the insertion of the Ti implant in a sheep model. The study was conducted on 12 sheep, 4 of which were control animals and 8 were in the experimental group with inserted Ti implant. Neutrophil secretory response was estimated at two time points T0 before surgery and T1 1 h after implantation and was based on the release of enzymes from neutrophil granules and reactive oxygen and nitrogen species (RONS) generation. MDM function was evaluated 5 months after implantation, on the basis of RONS generation arginase activity and morphological changes. Moreover, the influence of some autologous neutrophil derived products, namely, antimicrobial neutrophil extract (ANE) and neutrophil degranulation products (DGP) on leukocytes was estimated. Our study revealed that Ti implant insertion did not cause any adverse effects up to 5 months after surgical procedure. Stimulation of neutrophil cultures with ANE decreased the enzyme release as well as superoxide generation. Treatment of MDM with ANE diminished superoxide and NO generation and increased arginase activity. On the other hand, MDM stimulated with DGP showed elevated superoxide and NO generation as well as decreased arginase activity. To summarize, ANE exerted an anti-inflammatory and pro-resolving effect on studied leukocytes, whereas DGP acted as pro-inflammatory.

Development of combination vaccine conferring optimal protection against six pore-forming toxins of Staphylococcus aureus

In Gram-positive pathogen Staphylococcus aureus, pore-forming toxins (PFTs) such as leukocidins and hemolysins play prominent roles in staphylococcal pathogenesis by killing host immune cells and red blood cells (RBCs). However, it remains unknown which combination of toxin antigens would induce the broadest protective immune response against those toxins. In this study, by targeting six major staphylococcal PFTs (i.e., HlgAB, HlgCB, LukAB, LukED, LukSF-PV, and Hla), we generated ten recombinant toxins or toxin-subunits, three toxoids, and their rabbit antibodies. Using the cytolytic assay for RBCs and polymorphonuclear cells (PMNs), we determined the best combination of toxin antibodies conferring the broadest protection against those staphylococcal PFTs. Although anti-HlgA IgG (HlgA-IgG) showed low cross-reactivity to other toxin components, it was essential to protect rabbit and human RBCs and human PMNs. For the protection of rabbit RBCs, Hla_H35L toxoid-IgG was also required, whereas, for human PMNs, LukS-IgG and LukA_E323AB-IgG were essential too. When the toxin/toxoid antigens HlgA, LukS-PV, Hla_H35L, and LukA_E323AB were used to immunize rabbits, they increased rabbit survival; however, they did not block staphylococcal abscess formation in kidneys. Based on these results, we proposed that the combination of HlgA, LukS, Hla_H35L, and LukA_E323AB is the optimal vaccine component to protect human RBCs and PMNs from staphylococcal PFTs. We also concluded that a successful S. aureus vaccine requires not only those toxin antigens but also other antigens that can induce immune response blocking staphylococcal colonization.

Application of Natural Neutrophil Products for Stimulation of Monocyte-Derived Macrophages Obtained before and after Osteochondral or Bone Injury

We evaluated the use of some neutrophil products, namely; autologous rabbit antimicrobial neutrophil extract (rANE), heterologous porcine antimicrobial neutrophil extract (pANE), neutrophil degranulation products (DGP) and neutrophil microvesicles (MVs) for stimulation of monocyte-derived macrophages (MDMs) to improve healing. Two animal models were evaluated; the rabbit model for autologous osteochondral transplantation (OT) with application of rabbit ANE, DGP or MVs for MDMs stimulation, and the ovine model of the insertion of a Ti implant with the use of porcine ANE, and ovine DGP or MVs for MDMs stimulation. Macrophage activity was assessed on the basis of free radical generation and arginase activity. We estimated that DGP acted in a pro-inflammatory way both on rabbit and ovine MDMs. On the other hand, MVs acted as anti-inflammatory stimulator on MDMs in both experiments. The response to ANE depended on origin of extract (autologous or heterologous). Macrophages from rabbits before and after OT stimulated with autologous extract generated lower amount of NO and superoxide, especially after transplantation. In the ovine model of Ti implant insertion, heterologous ANE evoked increased macrophage pro-inflammatory activity. Our study revealed that these neutrophil products could regulate activity of macrophages, polarizing them into pro-or anti-inflammatory phenotypes that could enhance bone and osteochondral tissue healing.

Ozone therapy in veterinary medicine: A review

Ozone (O₃) is a triatomic form of oxygen. As O₃ rapidly dissociates into water and releases a reactive form of oxygen that may oxidize cells, the gas mixture of O₃/O₂ is used in medicine. ATP is widely available for cellular activity. O₃ can be administered via the systemic and local routes. Although O₃ is known as one of the most powerful oxidants, it also promotes antioxidant enzymes. Additionally, it stimulates some of the cells of the immune system and inactivates pathogens, including bacteria, fungi, yeasts, protozoa, and viruses. Owing to these activities, O₃ is used to improve several diseases, both in human and in veterinary medicine. Considering the wide scope of O₃ application, the aim of this review was to reiterate the mechanisms of action of O₃ and its utilization in different mammalian species (bovine, ovine-caprine, equine, canine, porcine).

Relationship Between Neutrophil Activity, Oxidative Stress, Acute Phase Response, and Lameness Grade in Naturally Occurring Acute and Chronic Joint Disorders in Horses

We hypothesized that in horses with naturally occurring joint disorders, the neutrophil response, acute phase response (APR), and oxidative stress parameters elevated significantly and are markers of increased inflammatory response in these conditions. Therefore, the first aim of the study was to evaluate neutrophil response, oxidative status, and APR. The neutrophil activity was assessed on the basis of elastase, myeloperoxidase (MPO), and alkaline phosphatase release, whereas free radical generation was assessed on the basis of nitric oxide and superoxide production. Acute phase response was estimated on the basis of fibrinogen or haptoglobin plasma concentration and oxidative stress on the basis of malondialdehyde plasma concentration. Then, these parameters were compared with lameness grade, and correlation coefficients between them were calculated. The study was conducted on 43 horses divided on control group of healthy horses (n = 17), acute lameness (AL) group (11 horses), and chronic lameness (CL) group (15 horses). The neutrophil activity from horses of both groups of joint disorders (AL and CL) was significantly (P < .01) higher in comparison with healthy horses. Elastase release was 67.28 ± 1.89% of maximal activity in AL group in comparison with 51.72 ± 1.75% in healthy horses and 62.61 ± 1.54% in CL group. The highest values of other enzymes were also noted in AL group. Moreover, in AL group release of elastase and MPO positively correlated (P < .01) with grades of lameness. These findings revealed the mutual relation between studied parameters and obtained results may be useful in the development of new therapeutic strategies in the treatment of acute and chronic joint disorders in horses.

The Role of Antimicrobial Neutrophil Extract in Modification of the Inflammatory Response During Osteochondral Autograft and Allograft Transplantation in Rabbits

Osteochondral autograft or allograft transplantation is one of the surgical options for the management of large cartilage defects; however, the mechanisms of cartilage healing after this procedure, especially the immunological mechanisms, are not fully understood. The present study examined whether a grafting procedure changed the in-vitro responses of neutrophils and monocyte-derived macrophages (MDMs). Additionally, antimicrobial neutrophil extract (ANE) was assessed for its ability to modulate excessive cellular responses during and after implantation. The neutrophil secretory response was tested by measuring enzyme release and free radical generation, while the MDM response was evaluated by assessing morphological and functional changes of the cells after polarization. Osteochondral implantation evoked a transient secretory response by circulating neutrophils, but MDMs were not activated postoperatively. ANE from rabbit blood may be considered as a modulator of the inflammatory response because of its influence on neutrophils and MDMs. Inhibition of the neutrophil secretory response prevents complications that may arise following excessive activity of these cells. Stimulation of MDMs with ANE induces formation of a partial anti-inflammatory phenotype with enhanced regenerative properties.

Changes in the Activity of Ovine Blood-derived Macrophages Stimulated with Antimicrobial Peptide Extract (AMP) or Platelet-rich Plasma (PRP)

Introduction

Antimicrobial peptides (AMP) are a large group of innate immune effectors, which apart from antimicrobial activity show immunomodulative properties. Platelet-rich plasma (PRP) is a source of autologous growth factors and is used for stimulation of bone and soft tissue healing. The purpose of this study was to assess the influence of PRP and AMP extract on ovine monocyte-derived macrophage cultures.

Material and Methods

The study was conducted on ovine macrophages (Mfs) previously stimulated with LPS or dexamethasone and then with preparations of PRP or AMP. Following activation of the Mfs their morphological and functional features were assessed.

Results

The study revealed pro-inflammatory influence of both examined preparations on Mfs cultures on the basis of morphology, ROS generation and arginase activity. Both preparations enhanced the pro-inflammatory response of cultured Mfs.

Conclusion

This activity may intensify the antimicrobial action of Mfs, however, in cases of excessive and prolonged inflammation the use of these preparations should be limited.

Application of Platelet-rich Plasma and Tricalcium Phosphate in the Treatment of Comminuted Fractures in Animals

AIM

To assess the applicability of β-tri-calcium phosphate (TCP) and platelet-rich plasma (PRP) in the treatment of comminuted fractures in small animals.

MATERIAL AND METHODS

The experimental study was carried out on 16 New Zealand White rabbits. After creating the bone defect and performing tibial osteotomy, TCP implants containing activated PRP were introduced into the fracture and the defect. The fracture was stabilised using external fixators or intramedullary nails. After 12 weeks, the animals were euthanised, and radiological, histological, scanning electron microscopy and peripheral quantitative computed tomography examinations were performed. The analysis also covered the results of fracture treatment in 37 small animals (cats and dogs) in which treatment with TCP containing PRP was used as an alternative to cancellous bone implantation.

RESULTS

Correct bone union was observed in the experimental groups, TCP remained visible at the site of the fracture after 12 weeks. In the clinical application in small animals, bone union was observed in over 91% of treated animals.

CONCLUSION

β-TCP and activated PRP may be an effective method of bone union enhancement in the treatment of comminuted fractures in small animals.

The Neutrophil Response to Rabbit Antimicrobial Extract After Implantation of Biomaterial into a Bone/Cartilage Defect

BACKGROUND/AIM

In this study, the neutrophil response to an antimicrobial extract was evaluated as a potential marker of inflammatory process after implantation of alginate and carbon fiber biomaterials into a bone or cartilage defect in rabbits.

MATERIALS AND METHODS

The response to biomaterials used was assessed based on enzyme release, generation of reactive oxygen species (ROS) and survival of neutrophils isolated from the rabbit's blood after implantation.

RESULTS

The implantation of alginate biomaterial increased elastase and alkaline phosphatase release, whereas carbon fibers did not evoke increased elastase release. The implantation of both biomaterials resulted in a higher myeloperoxidase (MPO) release after 30-min incubation. Stimulation with different fractions of antimicrobial peptide (AMP) extract diminished MPO release and nitric oxide generation, as well as slightly reducing neutrophil survival.

CONCLUSION

Our study permits the assessment of the neutrophil intravital response to an implant without the need for preparation of histological sections. Additionally, AMP extract restricted some manifestations of the pro-inflammatory response and may be considered a regulator of neutrophil activity in the early inflammatory phase, preventing rejection of the implant.

In vitro hemocompatability evaluation of gold nanoparticles capped with Lactobacillus plantarum derived lipase1

BACKGROUND

Gold nanoparticles (GNPs) are key diagnostic and therapeutic agents in biomedical sciences. Several studies have been carried out in different therapeutic areas such as in cancer treatment, antibacterial topical agents, imaging agents etc. There is a necessity to evaluate the gold nanoparticles cytotoxicity at all fronts. Since blood is the first point of contact in any therapy, it is required to have a thorough in vitro investigation of gold nanoparticles to avoid any adverse effects.

OBJECTIVE

The objective of the current study is to evaluate the effect of gold nanoparticles capped with lipase on blood clotting factors, platelets, coagulation time and blood clotting strength.

METHODS

Whole blood samples were drawn from healthy volunteers. Plasma and plasma with platelets were isolated from the blood and all the samples were treated with lipase capped gold nanoparticles, except control. Plasma fibrinogen formed in the blood coagulation process after contacting with nanoparticles was quantitatively evaluated. In addition, platelet aggregation, blood clotting kinetics, strength of the blood clot and time were evaluated post nanoparticle treatment.

RESULTS

The work primarily explores the effect of GNPs on blood with changing concentrations of lipase capping. Plasma fibrinogen levels of plasma samples were found to be moderately elevated, however, there is no significant effect on blood clotting kinetics, strength, and platelet aggregation. Also, the study showed that lipase capped GNPs did not result in aggregation upon interaction with plasma components and remained stable for 1 hour after incubation.

CONCLUSIONS

Our study revealed that lipase capped GNPs synthesized using NaBH4 approach were stable and hemocompatible. There is an increase in fibrinogen levels after the exposure to nanoparticles, an observation which is consistent with other studies. However, the functional consequences of such increase are unknown. The results of no significant platelet aggregation, change in blood clotting time, kinetics, and clot strength revealed the non-toxic effect of lipase capped GNPs towards blood components, which is essential for any in vivo applications.