Canine Platelet-Rich Plasma Systems: A Prospective Analysis

Growth factor and cytokine characterization of canine platelet lysate with variable leukocyte concentration, plasma content, and heat-sensitive proteins

Background

Platelet lysate is an acellular platelet product containing factors released from secretory granules, including cytokines and growth factors. This study aimed to evaluate different centrifugation methods used to prepare canine platelet lysate with variable content of leukocytes, plasma, and heat-sensitive proteins.

Methods

Whole blood was collected from six dogs and two double-spin preparation methods were used to generate the platelet-rich plasma with reduced (PRP) and high (L-PRP) concentration of leukocytes. A portion of both methods underwent plasma depletion via centrifugation and platelet lysate was generated via freeze-thaw cycles. A portion of the generated platelet lysate underwent complement inactivation via heat treatment. Growth factors (TGF-β1, VEGF, TNF-α, PDGF-BB, HGF) were quantified in all different platelet lysate preparations using ELISAs.

Results

Both platelet-rich plasma preparations had a 6.7-fold increase in platelet concentration. White blood cell (WBC) concentration compared to whole blood increased 1.2-fold times in PRP and 1.9-fold times in L-PRP. Negligible concentrations of platelets, WBC, and hematocrit were identified in all lysate groups. Statistically significant differences were identified for PDGF, VEGF, and TNF-α, and not for TGF-β or HGF. No growth factor differences were noted between centrifugation methods. PDGF was significantly higher in platelet lysate that was plasma depleted. VEGF was significantly higher in heat-treated lysate groups. TNF-α concentrations were overall very low, though were noted to significantly increase following plasma depletion.

Conclusion

These results support that growth factors and cytokine release can be affected by the platelet lysate preparation and processing.

The effect of two platelet-rich plasma aspiration techniques on plasma cellular concentrations using a double syringe gravitational centrifugation system

OBJECTIVE

To identify which aspiration technique increased plasma platelet concentration and which technique minimized plasma leukocyte and erythrocyte concentrations using a gravitational double-syringe platelet rich plasma (PRP) system.

STUDY DESIGN

Controlled laboratory study.

ANIMALS

Thirty adult dogs.

METHODS

Whole blood was collected into two autologous conditioned plasma (ACP) syringes and an ethylenediaminetetraacetic acid (EDTA tube) (control samples). The ACP syringes were centrifuged for 5 min at 1500 rpm. The proximal 2 mL of plasma from one ACP syringe was deposited in an EDTA tube (preflash samples). Plasma from the second ACP syringe was withdrawn until the buffy coat was pierced, producing a "flash" of red blood cells, agitated and deposited into an EDTA tube (flash samples). Complete blood counts were performed.

RESULTS

Mean plasma platelet concentrations of the control, preflash, and flash samples were 2.4 × 105/dL, 3.3 × 105/dL and 4.1 × 105/dL, respectively. The mean platelet concentration of the flash samples was 7.9 × 104/dL higher than the preflash samples (p = .005). The mean platelet concentration was lower in the control samples than the preflash (p = .002) and flash (p < .0001) samples. The median plasma leukocyte concentration of the preflash samples (0/dL) was lower than in the flash samples (2.4 × 103/dL) (p = .001). The median plasma hematocrit value of the preflash samples (0%) was lower than in the flash samples (1.0%) (p = .002).

CONCLUSION

The flash method is not necessary to produce a PRP sample.

CLINICAL SIGNIFICANCE

Both methods produced PRP. However, clinicians should avoid aspirating the buffy coat when processing PRP for therapies where leukocytes and erythrocytes are contraindicated.

The use of platelet rich plasma in the treatment of degenerative joint disease in cats: an exploratory case series

Objective

To evaluate the effectiveness of intra-articular autologous Platelet Rich Plasma (PRP) in managing Degenerative Joint Disease (DJD) in cats.

Design

Prospective pilot clinical trial.

Methods

Six domestic cats with clinically and radiographically diagnosed DJD received intra-articular injections of autologous PRP. Clinical assessments pre and post intra-articular injections were conducted using the Feline Musculoskeletal Pain Index (FMPI, owner assessed) and Visual Analog Scale (VAS, clinician assessed) at baseline, Day 14, Day 28, and Day 42-45.

Results

Significant improvements were noted in both FMPI and VAS scores at the end of the study period, indicating enhanced joint function and reduced pain.

Conclusion and clinical relevance

The study suggests the potential of PRP therapy as a safe and effective treatment for feline DJD, warranting further research with larger cohorts and longer follow-up to establish comprehensive treatment guidelines.

A Preliminary Report on the Combined Effect of Intra-Articular Platelet-Rich Plasma Injections and Photobiomodulation in Canine Osteoarthritis

Osteoarthritis (OA) is highly prevalent in the canine population. Due to the multiple dimensions of the disease, a multimodal approach is usually favored by clinicians. To evaluate the combined treatment with intra-articular platelet-rich plasma (PRP) and photobiomodulation in dogs with bilateral hip OA, thirty dogs were assigned to a PRP group (PRPG, n = 10), a photobiomodulation group (PBMTG, n = 10), or a combined therapies group (PRP+PBMTG, n = 10). The PRPG received two intra-articular administrations of platelet-rich plasma 14 days apart. The PBMTG received photobiomodulation with a therapeutic laser, with three sessions every other day in week one; two sessions in week two; a single session in week three; and one session/month on follow-up evaluation days. The PRP+PBMTG received the two combined therapies. The response to treatment was evaluated with weight-bearing distribution and the Canine Brief Pain Inventory, the Liverpool Osteoarthritis in Dogs, and the Canine Orthopedic Index. Evaluations were conducted before treatment and +8, +15, +30, +60, and +90 days after initial treatment. Normality was assessed with a Shapiro-Wilk test, and the groups' results in each evaluation moment were compared using a Mann-Whitney U test. Animals of both sexes (male n = 19, female n = 11) were included in the sample, with a mean age of 7.8 ± 2.5 years and a body weight of 26.5 ± 4.7 kg. Joints were classified as mild (n = 6, three in PRPG, two in PBMTG, and one in PRP+PBMTG), moderate (n = 18, six in PRPG, five in PBMTG, and seven in PRP+PBMTG), and severe (n = 6, one in PRPG, three in PBMTG, and two in PRP+PBMTG). No differences were found between groups at the initial evaluation. All treatments produced clinically significant improvements compared to the assessment on treatment day. The combination of PRP and photobiomodulation produced greater, longer-lasting improvements. PRP and photobiomodulation can improve objective outcomes and client-reported outcome measures in dogs with OA. Their combined use leads to greater, longer-lasting, clinically significant improvements.

Advances and prospects of platelet-rich plasma therapy in veterinary ophthalmology

In the recent decades, there has been a significant uptick on the use of platelet-rich plasma (PRP) as a better alternative for ophthalmologic therapies in pathologies, primarily of the ocular surface. PRP is a class of liquid platelet concentrate containing a supra-physiological concentration of platelets in a relatively small amount of plasma. Its potential to heal various tissues has piqued interest in its therapeutic application as a biomaterial in regenerative medicine. It is currently a popular therapeutic agent in plastic surgery, cardiothoracic surgery, reconstructive surgery, and even oral and maxillofacial surgery. Based on the data from in vitro and in vivo studies, it can be concluded that PRP possesses adequate therapeutic potential in ocular pathologies, especially those involving cornea. In addition, the high concentrations of growth factors (TGF-β, VEGF, EGF) present in the PRP accelerate the healing of the corneal epithelium. PRP has great therapeutic prospects in veterinary ophthalmology as a regenerative therapeutic modality. However, several variables are yet to be defined and standardized that can directly affect the efficacy of PRP application in different ophthalmic conditions. There is a shortage of research on the use of PRP in ocular surface defects compared to the number of studies and reports on the use of autologous and allogeneic serum eye drops. Therefore, a data-driven approach is required to generate consensus/guidelines for the preparation, characterization, and therapeutic use of PRP in veterinary ophthalmology. This review aims to inform readers of the latest research on PRP, including its preparation methods, physiological and biochemical properties, clinical applications in veterinary ophthalmology, and their safety and efficacy.

Platelet- Rich Plasma Treatment Supported by Ultrasound Detection of Septa in Recurrent Canine Aural Hematoma: A Case Series

Aural hematoma is a common pathological condition in veterinary practice with a high incidence rate in dogs. Drainage, corticosteroid injections, and surgical approaches represent the common treatments in these clinical cases. However, surgery leaves visible signs and is usually correlated with recurrence, scars, and deformation of the treated pinna. For this reason, more effective and less invasive methods have been proposed over the years. Platelet-Rich Plasma (PRP) is one of the most promising options due to its pro-regenerative properties and capability to modulate the inflammatory state. The present work reports 12 cases of canine aural hematoma treated with PRP. The PRP treatment was combined with an ultrasound evaluation of the pinna to detect and treat all involved septa. The results show that relatively large volumes (2 mL) of PRP associated with an ultrasound guide are safe and efficacious in the treatment of canine aural hematoma requiring a maximum of two infiltrations, both in acute and chronic conditions. All the patients recovered their normal ear thickness (compared with the controlateral one) without relapses, averaging 38.5 days from their first treatment (10-90 days; SD: 24.7). The key role of PRP combined with a tailored diagnosis process carried out by the veterinarian, which included using an ultrasound system and the proper bandage, suggests that this approach may represent a valid alternative to surgery and corticosteroids.

Human Platelet-Rich Plasma Regulates Canine Mesenchymal Stem Cell Migration through Aquaporins

Platelet products are commonly used in regenerative medicine due to their effects on the acceleration and promotion of wound healing, reduction of bleeding, synthesis of new connective tissue, and revascularization. Furthermore, a novel approach for the treatment of damaged tissues, following trauma or other pathological damages, is represented by the use of mesenchymal stem cells (MSCs). In dogs, both platelet-rich plasma (PRP) and MSCs have been suggested to be promising options for subacute skin wounds. However, the collection of canine PRP is not always feasible. In this study, we investigated the effect of human PRP (hPRP) on canine MSCs (cMSCs). We isolated cMSCs and observed that hPRP did not modify the expression levels of the primary class of major histocompatibility complex genes. However, hPRP was able to increase cMSC viability and migration by at least 1.5-fold. hPRP treatment enhanced both Aquaporin (AQP) 1 and AQP5 protein levels, and their inhibition by tetraethylammonium chloride led to a reduction of PRP-induced migration of cMSCs. In conclusion, we have provided evidence that hPRP supports cMSC survival and may promote cell migration, at least through AQP activation. Thus, hPRP may be useful in canine tissue regeneration and repair, placing as a promising tool for veterinary therapeutic approaches.

Submucosal Injection of Activated Platelet-Rich Plasma for Treatment of Periodontal Disease in Dogs

Periodontal disease is the most common oral disease seen in dogs, and its routine treatment usually involves dental scaling. Platelet-rich plasma (PRP) therapy may enhance the effectiveness of treatment of periodontal disease, delay the progression of the disease and decrease the time under anesthesia. However, its application in dogs is rarely discussed. The objective of this study was to evaluate the benefits of activated PRP for treatment of periodontal disease in dogs. 43 mL of whole blood was collected from six adult dogs and PRP extracted using the double centrifugation tube method. Subsequently, the PRP was activated using calcium chloride (A-PRP). Significantly elevated concentrations of PDGF-BB (7000.28 pg/mL), TGF-β (378.98 pg/mL), and VEGF (7.14 pg/mL) were detected in the A-PRP. Additionally, three of the dogs with stage 2-3 periodontal disease were enrolled in the clinical trial. Periodontal pocket depth, stage of periodontal disease, gingival index, horizontal bone loss, and alveolar bone density involving the maxillary third and fourth premolar and first molar teeth (107, 108, 109, 207, 208, and 209) were evaluated. Teeth were treated by dental scaling alone (control group) or by dental scaling followed by submucosal injection of 0.1 mL A-PRP per site. After 56 days, significant improvement in periodontal pocket depth, stage of periodontal disease, gingival index, and horizontal bone loss was observed in dogs injected with A-PRP. The high concentrations of growth factors in A-PRP likely contributed to this effect. The use of submucosal injections of A-PRP to treat canine stage 2-3 periodontal disease appears safe and effective for clinical practice.

Efficacy of autologous mesenchymal stromal cell treatment for chronic degenerative musculoskeletal conditions in dogs: A retrospective study

Introduction

The objective of this study was to retrospectively analyze clinical data from a referral regenerative medicine practice, to investigate the efficacy of autologous mesenchymal stromal cells (MSC) in 245 dogs deemed unresponsive to conventional treatment by their referring vet.

Methods

Diagnostic imaging [radiology and musculoskeletal ultrasound (MSK-US)] identified musculoskeletal pathology holistically. MSCs, produced according to current guidelines, were initially administered with PRP by targeted injection to joints and/or tendons, with a second MSC monotherapy administered 12 weeks later to dogs with severe pathology and/or previous elbow arthroscopic interventions. Dogs with lumbosacral disease received epidural MSCs with additional intravenous MSCs administered to dogs with spondylosis of the cervical, thoracic and lumbar spine. All dogs received laser therapy at 10 J/cm2 at the time of treatment and for 5 sessions thereafter. Objective outcome measures (stance analysis, range of joint motion, pressure algometry) and validated subjective outcome measures (owner reported VetMetrica HRQL™ and veterinary pain and quality of life impact scores) were used to investigate short and long-term (6-104 weeks) efficacy. Outcome data were collected at predetermined time windows (0-6, 7-12, 13-18, 19-24, 25-48, 49-78, 79-104) weeks after initial treatment.

Results

There were statistically significant improvements in post compared with pre-treatment measures at all time windows in stance analysis, shoulder and hip range of motion, lumbosacral pressure algometry, and to 49-78 weeks in carpus and elbow range of motion. Improvements in 4 domains of quality of life as measured by VetMetricaTM were statistically significant, as were scores in vet-assessed pain and quality of life impact. In dogs receiving one initial treatment the mean time before a second treatment was required to maintain improvements in objective measures was 451 days. Diagnostic imaging confirmed the regenerative effects of MSCs in tendinopathies by demonstrating resolution of abnormal mineralization and restoration of normal fiber patterns.

Discussion

This represents the first study using "real-world" data to show that cell-based therapies, injected into multiple areas of musculoskeletal pathology in a targeted holistic approach, resulted in rapid and profound positive effects on the patient's pain state and quality of life which was maintained with repeat treatment for up to 2 years.

Leukocyte and Platelet-Rich Plasma (L-PRP) in Tendon Models: A Systematic Review and Meta-Analysis of in vivo/in vitro Studies

Purpose

To perform a systematic review on the application of leukocyte- and platelet-rich plasma (L-PRP) in tendon models by reviewing in vivo/in vitro studies.

Methods

The searches were performed via electronic databases including PubMed, Embase, and Cochrane Library up to September 2022 using the following keywords: ((tenocytes OR tendon OR tendinitis OR tendinosis OR tendinopathy OR tendon injury) AND (platelet-rich plasma OR PRP OR autologous conditioned plasma OR leukocyte- and platelet-rich plasma OR L-PRP OR leukocyte-richplatelet-rich plasma Lr-PRP)). Only in vitro and in vivo studies that assessed the potential effects of L-PRP on tendons and/or tenocytes are included in this study. Description of PRP, study design and methods, outcomes measured, and results are extracted from the data.

Results

A total of 17 studies (8 in vitro studies and 9 in vivo studies) are included. Thirteen studies (76%) reported leukocyte concentrations of L-PRP. Four studies (24%) reported the commercial kits. In in vitro studies, L-PRP demonstrated increased cell proliferation, cell migration, collagen synthesis, accelerated inflammation, and catabolic response in the short term. In addition, most in vivo studies indicated increased collagen type I content. According to in vivo studies reporting data, L-PRP reduced inflammation response in 71.0% of studies, while it enhanced the histological quality of tendons in 67.0% of studies. All 3 studies reporting data found increased biomechanical properties with L-PRP treatment.

Conclusions

Most evidence indicates that L-PRP has some potential effects on tendon healing compared to control. However, it appears that L-PRP works depending on the biological status of the damaged tendon. At an early stage, L-PRP may accelerate tendon healing, but at a later stage, it could be detrimental.

Effect of Leukoreduced Platelet Rich Plasma on Intra-Articular Pro-Inflammatory Cytokines in a Canine Pilot Study

Simple Summary

This study provides initial information on the effect of platelet rich plasma in some of the most important pro-inflammatory cytokines identified in osteoarthritic stifle joint in dogs. The use of platelet rich plasma is getting more popular in the veterinary field but its effect in those cytokines is not known.

Abstract

Evaluation of effect of Leukoreduced Platelet Rich Plasma (LrPRP) on TNF-α and IL-6 (pro-inflammatory cytokines) in joint fluid in dogs with cranial cruciate ligament rupture (CCLR). Eight client-owned dogs with CCLR were assigned to treatment (2 mL LrPRP) or control (2 mL saline) injection groups. Day of evaluation (day 0) and day of surgery (day 10–14), joint fluid was collected and joint injected. Joint fluid was also collected on day of suture removal (day 20–28). TNF-α and IL-6 concentrations of joint fluid were measured using a bead-based antibody assay. Concentrations at the later time points were expressed as a ratio to the initial level within each stifle. LrPRP had a mean concentration of platelets 1.7 times higher that of whole blood on day of evaluation and 1.4 times higher on day of the surgery. Leukocytes were reduced by 99.7%. On day of surgery, TNF-α ratios in the joint fluid from dogs injected with LrPRP were significantly different that TNF-α ratios of control group. On the day of suture removal ratios of IL-6 and TNF-α were lower in LrPRP treatment group compared with control group; however, differences were not significant. LrPRP modulate ratios of pro-inflammatory cytokine TNF-α in dogs with CCLR.

Locally Injected Autologous Platelet-Rich Plasma Improves Cutaneous Wound Healing in Cats

Cutaneous defects in cats are commonly encountered in clinical practice, and healing can be accomplished by first or second intention. Platelet-rich plasma (PRP) is characterized by a plasma concentration containing a large number of platelets in a small volume of plasma. The objective of the present study was to record the efficacy of PRP infiltration in open wounds in laboratory cats. Six wounds were created in the dorsal midline of eight laboratory cats, with the wounds of one side designated as the PRP group and the wounds of the other side as the control group. Wound healing was evaluated by daily clinical examination, planimetry, laser Doppler flowmetry, and histologic examination on days 0, 7, 14, and 25, and by measurement of metalloproteinases (MMPs)-2 and -9 and tissue inhibitor metalloproteinase (TIMP)-1 on days 0, 14, and 25. Based on the results of the present study, the mean time for full coverage with granulation tissue was shorter in the PRP group, the mean contraction and total wound healing percentage were increased compared to the control group, and finally, the perfusion measured with laser Doppler flowmetry was higher in the PRP group during all examination days. In conclusion, this is the first study focusing on the topical application of PRP in the treatment of open wounds in laboratory cats, and our results are encouraging—showing a more rapid healing in the PRP group.

Local wound management: A review of modern techniques and products

Management of wounds is a commonly performed and essential aspect of small animal veterinary medicine. Appropriate wound management is a difficult art to master, due to the inherent complexity of the clinical scenario, as well as the ever-evolving nature of the field with the constant addition of new products and techniques. This article reviews key concepts that may help the practitioner better understand the natural process of wound healing, factors that delay healing and strategies to help improve the local wound environment to make it more conducive to healing during open wound management. The concept of wound bed preparation is defined before common local wound management strategies, such as wound lavage and debridement, are discussed in more detail. Key aspects of the management of biofilms and appropriate use of antimicrobial agents are also reviewed. Finally, the concept of moist wound healing and its impact in modern wound management is explained before a broad variety of types of wound dressings are reviewed, with a particular focus on active dressings.

Platelet-Rich Plasma as an Orthobiologic: Clinically Relevant Considerations

Platelet-rich plasma (PRP) is an autologous blood-derived product processed to concentrate platelets and the associated growth factors. PRP has been shown to be relatively well-tolerated and safe to use for a number of conditions in humans, equines, and canines. There are multiple commercial systems that have been validated for canine use. These systems use a variety of methodologies to produce a PRP product. However, PRP products have been shown to differ greatly between systems. Further study is needed to fully elucidate optimal component concentrations for various indications.

Proposed Canadian Consensus Guidelines on Osteoarthritis Treatment Based on OA-COAST Stages 1–4

The Canadian consensus guidelines on OA treatment were created from a diverse group of experts, with a strong clinical and/or academic background in treating OA in dogs. The document is a summary of the treatment recommendations made by the group, with treatments being divided into either a core or secondary recommendation. Each treatment or modality is then summarized in the context of available research based support and clinical experience, as the treatment of OA continues to be a multimodal and commonly a multidisciplinary as well as individualized approach. The guidelines aim to help clinicians by providing clear and clinically relevant information about treatment options based on COAST defined OA stages 1–4.

Evaluation of Platelet and Leukocyte Counts in Canine Platelet-Rich Plasma Obtained After Successive Blood Collections From the Same Patient and the Effects of Freezing on the Concentration of Growth Factors Present in It

Objective

The purpose of this study was 2-fold: to evaluate whether the timing of collection influences the platelet counts and leukocyte counts of PRP samples, and to evaluate growth factor concentrations in canine PRP after freezing and storage without a preservation agent for 6 months of time.

Materials and Methods

Whole blood collection was performed three times over the course of 4 weeks. All PRP samples were evaluated with a CBC analysis. The PRP samples were frozen and stored without a preservation agent for the duration of the 4-week study.

Results

The platelet and leukocyte counts were not statistically significant between the timing of blood draws over the course of 4 weeks. All three growth factors were present in measurable quantities after freezing and storage for 6 months without a preservation agent.

Clinical Relevance

PDGF, TGF-β1, and VEGF were all present in measurable quantities. Furthermore, PDGF and TGF-β1 were correlated with platelet count of the final PRP. VEGF concentrations were able to be quantified. We correctly hypothesized growth factor concentrations would be present and measurable in canine PRP frozen and stored without a preservation agent for 6 months.

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.

Platelet Lysate for Mesenchymal Stromal Cell Culture in the Canine and Equine Species: Analogous but Not the Same

Simple Summary

Regenerative medicine using platelet-based blood products or adult stem cells offers the prospect of better clinical outcomes with many diseases. In veterinary medicine, most progress has been made with the development and therapeutic use of these regenerative therapeutics in horses, but the clinical need is given in dogs as well. Our aim was to transfer previous advances in the development of horse regenerative therapeutics, specifically the use of platelet lysate for feeding stem cell cultures, to the dog. Here, we describe the scalable production of canine platelet lysate, which could be used in regenerative biological therapies. We also evaluated the canine platelet lysate for its suitability in feeding canine stem cell cultures in comparison to equine platelet lysate used for equine stem cell cultures. Platelet lysate production from canine blood was successful, but the platelet lysate did not support stem cell culture in dogs in the same beneficial way observed with the equine platelet lysate and stem cells. In conclusion, canine platelet lysate can be produced in large scales as described here, but further research is needed to improve the cultivation of canine stem cells.

Abstract

Platelet lysate (PL) is an attractive platelet-based therapeutic tool and has shown promise as xeno-free replacement for fetal bovine serum (FBS) in human and equine mesenchymal stromal cell (MSC) culture. Here, we established a scalable buffy-coat-based protocol for canine PL (cPL) production (n = 12). The cPL was tested in canine adipose MSC (n = 5) culture compared to FBS. For further comparison, equine adipose MSC (n = 5) were cultured with analogous equine PL (ePL) or FBS. During canine blood processing, platelet and transforming growth factor-β1 concentrations increased (p < 0.05 and p < 0.001), while white blood cell concentrations decreased (p < 0.05). However, while equine MSC showed good results when cultured with 10% ePL, canine MSC cultured with 2.5% or 10% cPL changed their morphology and showed decreased metabolic activity (p < 0.05). Apoptosis and necrosis in canine MSC were increased with 2.5% cPL (p < 0.05). Surprisingly, passage 5 canine MSC showed less genetic aberrations after culture with 10% cPL than with FBS. Our data reveal that using analogous canine and equine biologicals does not entail the same results. The buffy-coat-based cPL was not adequate for canine MSC culture, but may still be useful for therapeutic applications.

Clinical Cohort Study in Canine Patients, to Determine the Average Platelet and White Blood Cell Number and Its Correlation with Patient's Age, Weight, Breed and Gender: 92 Cases (2019-2020)

Due to its easy preparation and that it is well tolerated, the use of autologous platelet-rich plasma (PRP) has become increasingly popular in regenerative medicine. However, there are still no clear guidelines on how it should be classified or whether the individual canine patient’s clinical status can influence its quality. Objective: This study aims to show if the weight, age, sex, neutered status or breed of canine patients have any correlation with the composition of PRP. Design: A blinded count of the platelets and white blood cells (WBC) was performed from 111 samples from 92 client owned dogs undergoing treatment for degenerative joint disease (DJD). The results were analysed using Pearson correlation test, ANOVA test or Student T-test. Results: There is a positive correlation between the number of platelets and WBC in canine patients of different breeds, but there was no significant difference on the platelet number and WBC number among the different breeds. The weight of the patient is also directly correlated to the platelet number (p = 0.003) but not WBC number. WBC number was negatively correlated to the weight of the patient. The sex and age of the patient did not affect platelets and WBC number, although WBC number is increased in non-neutered male population (p = 0.003). However, it would be interesting to investigate whether the growth factors released from the platelet granules are affected by patient variables in a canine population. Conclusions: Our results show that it is possible to obtain good quality autologous PRP, irrespective of age, sex, neutered status or weight of the patient, for PRP regenerative therapy.

Therapeutic Potential of Platelet-Rich Plasma in Canine Medicine

Platelets are the reservoir of growth factors and play a major role in several physiological processes, such as coagulation, angiogenesis, immune response, and tissue repair. Platelet concentrates are broadly classified into two groups depending on their fibrin content, namely platelet-rich plasma (PRP) and platelet-rich fibrin (PRF). They are further divided based on their leucocyte contents. The PRP is plasma containing supra-physiological concentrations of the platelets. The growth factors present in the PRP play a crucial role in the promotion of local angiogenesis, regulation of cellular activity, stem cell homing, proliferation and differentiation of different stem cells, and deposition of matrix proteins contributing to tissue regeneration. This review aimed to establish the therapeutic potential of PRP in canine medicine with a particular focus on the applications in ophthalmology, dermatology, and musculoskeletal disorders. A systematic literature review was performed to identify the literature published during the past 20 years (2001-2021) using authentic academic databases, such as PubMed, Science Direct, Google Scholar, and Scopus. In the initial search, 556 articles were identified and based on the specific inclusion and exclusion criteria, 59 articles were selected for further analysis. The clinical efficacy of PRP depends on the number of platelets and the growth factor concentration. The PRP-based biological therapy has broad clinical applications in musculoskeletal pathologies. It is a simple, safe, and cost-effective method that can be used to treat various diseases and disorders in canine practice. For example, PRP is used for managing corneal ulcers, corneal erosion, alkali burn, keratoconjunctivitis sicca, burn wounds, chronic wounds, cutaneous ulcers, acute traumatic bone fractures, tendinopathies, cartilage pathologies, osteoarthritis, and abdominal wall defects either as monotherapy or as an adjunctive therapeutic agent. In addition, PRP is widely used as a carrier of mesenchymal stem cells for transplanting into bone defects. Therefore, allogeneic PRP therapy can be considered a simple, safe, and cost-effective method for the treatment of various diseases and disorders in canine practice. The therapeutic application of PRP in canine medicine is limited in the present study due to the lack of consensus for collection, characterization, and clinical use. Hence, further studies are required to establish the actual worth of PRP-based regenerative strategies in canine medicine.

Platelet-rich plasma therapy in dogs with bilateral hip osteoarthritis

Background

Osteoarthritis (OA) is the most commonly diagnosed joint disease in companion animals, and hip OA is commonly diagnosed in the canine population. The use of platelet-rich plasma has gained increasing interest for the treatment of musculoskeletal conditions in companion animals. To evaluate the effect of the intra-articular administration of platelet-rich plasma in police working dogs with bilateral hip OA compared to a control group, twenty dogs were assigned to a control group (CG, n = 10) or treatment group (PG, n = 10), using the statistical analysis software. PG received two intra-articular administrations of platelet-rich plasma, 14 days apart, while CG received an intra-articular administration of saline, in the same moments. Response to treatment was determined with the Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, Canine Orthopedic Index, and Hudson Visual Analogue Scale, before treatment, + 8, + 15, + 30, + 60, + 90, + 120, 150, and + 180 days after initial treatment. Kaplan-Meier estimators were conducted and compared with the log-rank test. Cox proportional hazard regression analysis was performed to determine treatment survival, p < 0.05.

Results

The sample comprised 20 animals of both sexes (male n = 12, female n = 8), with a mean age of 8.4 ± 2.4 years and a bodyweight of 31.5 ± 5.7 kg. Joints were classified as moderate (13) and severe (7) according to the Orthopedic Foundation for Animals grading scheme. No differences were found between groups at the initial evaluation. Better results with the majority of scores were observed in the PG, in some cases lasting up to the last evaluation moment. Kaplan-Meier estimators showed that PG produced longer periods with better results in all scores compared to CG. Treatment was the covariate influencing all scores in the Cox regression analysis. OFA hip score also influenced two dimensions of the Canine Orthopedic Index.

Conclusion

The intra-articular administration of platelet-rich plasma can improve pain and functional scores of police working dogs with bilateral hip OA, compared with a control group. Its effects lasted for significantly longer periods, and treatment was the main covariate affecting the improvements observed.

Platelet-Rich Plasma Centrifugation Changes Leukocyte Ratios

Platelet-rich plasma (PRP) is usually described with respect to its platelet concentration and sometimes the concentration of erythrocytes and leukocytes. In this study, we examined the numbers of leukocyte subtypes in PRPs prepared by five different methods. Single spin PRP methods evaluated resulted in a significant increase in the percentage of lymphocytes and proportional/inverse reduction of the percentage of granulocytes in comparison to those percentages found in whole blood. We propose that the centrifugation process traps the denser granulocytes in the RBC layer more readily than lymphocytes and that this will vary by g force and time. The PRP preparation method may be clinically relevant, because the distribution of leukocytes may affect clinical outcomes.

The Use of Autologous Protein Solution (Pro-Stride®) and Leukocyte-Rich Platelet-Rich Plasma (Restigen®) in Canine Medicine

The use of autologous orthobiologics is an emerging area of interest in veterinary medicine. In this retrospective study, we reviewed the clinical results achieved using two orthobiologics devices to address orthopedic injuries and tissue repair. Leukocyte (White blood cell)-rich platelet-rich plasma (L-PRP) devices produce outputs containing high concentrations of growth factors from venous blood. The Autologous Protein Solution (APS) device produces an orthobiologic containing high concentrations of growth factors and anti-inflammatory cytokines. L-PRP has commonly been used to address soft tissue injuries. APS has been injected into the joint to address osteoarthritis. In the last five years, our practice has treated 35 dogs (38 treatments) with L-PRP and 98 dogs (108 treatments) with APS. Our group has used L-PRP and APS to address orthopedic conditions including osteoarthritis, bursitis, tendinitis, tendon/ligament rupture/repair procedures, post-surgical femoral head osteotomy/tibial-plateau-leveling osteotomy tissue repair, lumbosacral stenosis, patellar luxation, joint laxity, and osteochondral dissecans. The results achieved with L-PRP and APS have been favorable (observed pain improvement and minimal adverse reactions), but sometimes have not achieved complete pain relief or tissue repair. The most common application for L-PRP was patellar luxation and the most common application for APS was injection post-ACL surgery. Canine OA has been successfully managed in several patients with repeat injections of APS over the course of several years. Future studies on specific conditions are ongoing and including efforts to further characterize these products in canine medicine.

Intra-articular Injections With Either Triamcinolone Hexacetonide, Stanozolol, Hylan G-F 20, or a Platelet Concentrate Improve Clinical Signs in Police Working Dogs With Bilateral Hip Osteoarthritis

Objectives: To compare the effect of intra-articular treatment with triamcinolone hexacetonide (TH), stanozolol, hyaluronan, and a platelet concentrate in police working dogs with bilateral hip osteoarthritis (OA). Study Design: Prospective, longitudinal, double-blinded, negative controlled study. Sample Population: Fifty police working dogs with naturally occurring hip OA. Methods: Animals were randomly assigned to a control group (CG, n = 10), TH group (THG, n = 10), platelet concentrate group (PCG, n = 10), stanozolol group (SG, n = 10), and Hylan G-F 20 group (HG). On days 0 (T0), 8, 15, 30, 90, and 180 days post-treatment, weight-bearing distribution was evaluated. In those days, and on days 60, 120, and 150, four clinical metrology instruments were completed. Kaplan-Meier estimators were conducted and compared with the log-rank test. Cox proportional hazard regression analysis was performed to determine treatment survival. Significance was set at p < 0.05. Results: Patients had a mean age of 6.5 ± 2.4 years and body weight of 26.7 ± 5.2 kg. At T0, hips were classified as mild (n = 35), moderate (n = 10), and severe (n = 5), according to the Orthopedic Foundation for Animals grading scheme. No differences were found between groups at that moment considering age, body weight, OFA hip score, and all assessments performed. All treatments improved clinical signs in various OA dimensions in some groups, with a broad effect interval. PCG showed a lower range of variation while maintaining a positive result for more extended periods (p < 0.01 for symmetry index and 0.01 < p < 0.04 in the majority of scores). Breed, age, sex, and OFA grade did not significantly influence response to treatment. Conclusions and Clinical Relevance: This is the first prospective, negative controlled, double-blinded study to compare the effect of a single administration of these IA treatments in dogs with hip OA. HG and PCG recorded more significant improvements throughout the 180-day follow-up. In particular, PCG also registered a lower variation in results, seemingly the best therapeutic option. Nevertheless, improvements were still observed in THG and SG, and these treatment options can be considered, mainly when the first two treatments are not available.

The Stryker Regenkit PRP Kit Does Not Concentrate Canine Platelets

Platelet Rich Plasma (PRP) works to recruit growth factors, anti-inflammatory mediators, and blood supply to an area that may not heal well under normal conditions (e.g., joints, tendons, ligaments). Previous research has demonstrated that various PRP systems create vastly different final products. The objective of this study was to evaluate the cellular composition of the final plasma product using the Stryker RegenKit system in dogs. A peripheral blood sample was obtained from ten healthy adult dogs and compared to the final plasma product. A standard CBC was performed prior to testing and an additional sample was processed according the manufacturing guidelines for obtaining PRP (10 ml total blood). Comparisons of mean platelet count, erythrocyte count, and leukocyte count were made between the peripheral blood sample and the final plasma product. Results showed that there was no significant difference in platelet count between the peripheral blood CBC and final PRP CBC (p = 0.349). There were significantly fewer erythrocytes and leukocytes in the final plasma product when compared with peripheral blood (p = < 0.0001, p = 0.0318, respectively). These results indicate that the Stryker Regenkit PRP Kit decreases leukocyte and erythrocyte concentrations but does not consistently change platelet concentrations in its final plasma product. This study, in combination with results from similar studies, may allow clinicians to better choose the appropriate PRP system to treat various musculoskeletal conditions in dogs.

Platelet-Derived Products in Veterinary Medicine: A New Trend or an Effective Therapy?

Platelet-derived products (PDPs) have gained popularity, mainly due to their high concentrations of bioactive molecules such as growth factors and cytokines, which play important roles in tissue healing and regeneration. PDPs are obtained through minimally invasive procedures and their therapeutic effect has been widely recognized. In veterinary medicine, however, the lack of standard protocols to generate PDPs is a major hurdle for assessing the clinical relevance of PDP-based therapies and for their widespread usage. The aim of this review is to analyze the technical and scientific specificities of PDPs in terms of preparation methodologies, classification categorization, nomenclature, and biological proprieties to advance their future biotechnological potential in veterinary contexts.

Validation and Characterization of Platelet-Rich Plasma in the Feline: A Prospective Analysis

Objective: To quantitate key parameters of the platelet-rich plasma (PRP) product from a commercially available system¹ in healthy, adult felines.

Materials and methods: A prospective study was performed from January 2019 to April 2019. 11 adult, healthy cats were used to prospectively analyze a commercially available PRP system¹. A whole blood sample and a PRP sample that was processed immediately following blood draw according to the manufacturer's protocol were collected from each cat. The mean whole blood and PRP product platelet, RBC, WBC, neutrophil, monocyte, and lymphocyte concentrations were determined. The mean PRP product values were compared to the mean whole blood baseline values using a paired t-test with significance established at p = 0.05.

Results: Mean platelet concentration was significantly increased (p = 0.0155). Mean RBC concentration was significantly decreased (p < 0.0001). Mean neutrophil concentration was significantly decreased (p < 0.0001). There was no statistically significant difference in mean WBC, monocyte, and lymphocyte concentrations.

Clinical Relevance: The analyzed PRP system increased platelet concentration, while significantly reducing the RBC and neutrophil concentrations. Further study is warranted to determine the clinical applications and efficacy of PRP in felines, and the ideal concentrations of and relationships between platelets, red blood cells, and leukocytes needed for therapeutic effect.

Efficacy of a Semi Automated Commercial Closed System for Autologous Leukocyte- and Platelet-Rich Plasma (l-prp) Production in Dogs: A Preliminary Study

BACKGROUND

To characterize the cellular composition (platelets, erythrocytes, and leukocytes) and determine platelet-derived growth factor isoform BB (PDGF-BB) concentration in canine leukocyte- and platelet rich plasma (L-PRP) produced using a commercial semi-automated closed system.

METHODS

Twenty milliliters of citrated whole blood were obtained from 30 healthy un-sedated canine blood donors and processed using a semi-automated completely closed commercial system (CPUNT 20, Eltek group, Casale Monferrato, Alessandria, Italy) according to the manufacturer's instructions. Erythrocyte, leukocyte, and platelet counts were determined in both whole blood (WB) and resultant L-PRP. The PDGF-BB concentration was evaluated after bovine thrombin activation of 10 L-PRP samples.

RESULTS

This commercial system produced on average 2.3 ± 0.7 mL of L-PRP containing a high concentration of platelets (767,633 ± 291,001 μL, p < 0.001), with a 4.4 fold increase in platelet count, lower concentration of erythrocytes (528,600 ± 222,773 μL, p < 0.001) and similar concentration of leukocytes (8422 ± 6346 μL, p = 0.9918) compared with WB. L-PRP had an average of 3442 ± 2061 pg/mL of PDGF-BB after thrombin activation. Neutrophils, lymphocytes and monocytes average percent content in L-PRP was 14.8 ± 13.2, 71.7 ± 18.5 and 10.7 ± 6.4, respectively.

CONCLUSION

Sterile canine L-PRP prepared using this semi-automated closed system is easy to obtain, produces a significant increase in platelet count compared to WB and contains a detectable concentration of PDGF-BB after activation. Additional in vitro and in vivo studies are needed to assess inflammatory markers concentration and the therapeutic efficacy of this L-PRP in dogs.

Prospective Evaluation of Feline Sourced Platelet-Rich Plasma Using Centrifuge-Based Systems

Objective: To evaluate the hematologic components of platelet-rich plasma (PRP) generated using feline blood with two commercially available centrifuge-based systems^1,2.

Materials and methods: Twenty healthy adult cats were enrolled in this prospective study from November 2018 to January 2019. Feline blood samples were obtained for analysis of whole blood (WB) cellular components and preparation of PRP product. PRP was prepared using two commercial systems and complete blood count (CBC) testing was performed on both WB and PRP samples. The cellular composition of the PRP product was compared to the WB sample for each patient.

Results: Both systems showed significant decrease of median RBC concentration in PRP products compared to WB samples (P = 0.002 for both systems). System 1 significantly decreased median WBC concentration (P = 0.002). System 2 decreased WBC concentration, though statistical significance was not reached (P = 0.63). Median platelet concentration was decreased by 3% using System 1, and increased by 187% using System 2. Platelet aggregation presented a challenge with 8/20 (40%) of samples demonstrating platelet aggregation.

Clinical relevance: Commercial systems available for generation of PRP may be useful for creating a feline sourced product and in this study showed promise in decreasing RBC and WBC concentration. Neither system tested achieved 2–5 times platelet concentration from baseline. Platelet aggregation presented a significant obstacle to reliable generation of PRP products using feline blood. This treatment modality may be particularly beneficial for feline patients with osteoarthritis and soft tissue injuries, though first characterizing the PRP product made using feline blood is critical to validate its use in further clinical studies.

Platelet-rich plasma (PRP) therapy: An approach in reproductive medicine based on successful animal models

Platelet-rich plasma (PRP) has been fully studied for different clinical applications in veterinary medicine for many years with promising results. As a result, therapeutic studies to elucidate pathways for PRP use in human reproduction have been performed. PRP applications in human reproductive medicine are recent, but the role of platelet growth factors in improving the endometrial environment is well known. Indications for PRP therapy show its positive effects in promoting endometrial and follicular growth and gestation in assisted reproduction cycles, as has been proven in animals. We summarized the putative role of PRP on endometrial receptivity with a brief history of promising results in research and clinical therapies.

Optimization of a rapid one-step platelet-rich plasma preparation method using syringe centrifugation with and without carprofen

Background

Carprofen and platelet-rich plasma (PRP) are widely used in small animal clinical practice. Separation layers have been used during blood centrifugation to increase platelet yield. The objectives of this study were to (1) identify the optimal centrifugation force for the one-step PRP preparation, (2) determine whether there is an advantage to using carprofen in one-step PRP preparation, and (3) compare platelet morphology from one-step PRP preparation with and without carprofen. We hypothesized that injectable carprofen (emulsion formula) could be used successfully as the separation layer in PRP preparation.

Results

Samples from 14 healthy dogs were used to determine the optimal centrifugation force using one-step PRP preparation in a disposable syringe without carprofen, with forces set at 300, 500, 700, 900, 1100, 1300, and 1500 xg for 5 min. Optimum centrifugation force, plasma volume, and platelet concentrations of one-step PRP preparation were found and recovered at 900 xg, 1.9 ± 0.28 ml, and 260.50 ± 58.39 X 10³ cell/μl, respectively. Samples from 12 healthy dogs were used to determine the optimal force (with forces set at 300, 500, 700, and 900 xg) for 5 min using one-step PRP preparation with carprofen. Optimum centrifugation force, plasma volume, and platelet concentrations for one-step PRP preparation with carprofen were found and recovered at 500 xg, 0.62 ± 0.16 ml and 948.50 ± 261.40 X 10³ cell/μl, respectively. One-step PRP preparation with carprofen increased the platelet yield from baseline by 1.76 and 4.95 fold, respectively. Samples from 3 healthy dogs were used to observe platelet morphologies after centrifugation by scanning electron microscopy. Images of platelets on glass slides from both preparation methods revealed pseudopods emerging from the margins of the discoid platelets.

Conclusions

One-step PRP centrifugation both with and without carprofen increased the platelet yield, but using carprofen (emulsion formula) as a separation layer resulted in a higher platelet yield. The clinical usefulness of PRP products from these methods should be further investigated.

Platelet Function and Therapeutic Applications in Dogs: Current Status and Future Prospects

Significant progress has been made in the functional characterization of canine platelets in the last two decades. The role of canine platelets in hemostasis includes their adhesion to the subendothelium, activation, and aggregation, leading to primary clot formation at the site of injury. Studies on canine platelet function and advancements in laboratory testing have improved the diagnosis and understanding of platelet-related disorders as well as the knowledge of the mechanisms behind these diseases. This review focuses on the most recent discoveries in canine platelet structure, function, and disorders; and discusses the efficacy of various tests in the diagnosis of platelet-related disorders. With the relatively recent discovery of angiogenetic and reparative effects of growth factors found in platelets, this review also summarizes the use of canine platelet-rich plasma (PRP) alone or in association with stem cells in regenerative therapy. The characterization of proteomic and lipidomic profiles and development of platelet gene therapy in veterinary species are areas of future study with potential for major therapeutic benefits.

Clinical trial of adjunctive autologous platelet-rich plasma treatment following diamond-burr debridement for spontaneous chronic corneal epithelial defects in dogs

OBJECTIVE To evaluate the effects of adjunctive treatment with autologous platelet-rich plasma (PRP) on corneal reepithelialization, vascularization, and fibrosis in dogs with spontaneous chronic corneal epithelial defects (SCCEDs). DESIGN Randomized, controlled, double-masked clinical trial. ANIMALS 40 client-owned dogs with uncomplicated SCCEDs. PROCEDURES All dogs were treated with diamond-burr epithelial debridement (DBD) of affected eyes, topical tobramycin solution and atropine sulfate ointment application, and Elizabethan collar placement for 4 weeks. Dogs were randomly assigned to topical ocular administration of autologous PRP (n = 20) or artificial tear solution (control group; 20) 4 times daily for 28 days. Recheck examinations were performed approximately 2 and 4 weeks after treatment began to evaluate SCCEDs for corneal reepithelialization, and semiquantitative corneal vascularization and corneal fibrosis scores were assigned according to affected corneal surface area. Results were compared between groups. RESULTS All dogs completed the study. The SCCEDs had completely reepithelialized in 11 (55%) control dogs and 12 (60%) PRP-treated dogs by the 2-week reevaluation, and in 15 (75%) control dogs and 18 (90%) PRP-treated dogs by the 4-week reevaluation. No significant differences were identified between groups in these proportions nor in mean differences from pretreatment scores for corneal vascularization and fibrosis. CONCLUSIONS AND CLINICAL RELEVANCE In this preliminary study involving dogs with uncomplicated SCCEDs, topical PRP administered as an adjunctive treatment following DBD had no significant effect on healing. A larger study is warranted to support or refute these findings and to determine the effects of adjunctive PRP treatment for dogs with complicated SCCEDs.

Comparison of the methods for platelet rich plasma preparation in horses

Platelet rich plasma (PRP) is popularly used in the horse industry to enhance regeneration of tissue injury that has limitation of blood supply. This study aimed to compare the methods for platelet rich plasma preparation since they has not been established yet. Blood was collected from six horses and platelets were concentrated by three different methods (2-step centrifugation, separated centrifugation and separated centrifugation using histopaque). Concentrated blood was analyzed using Advia hematology systems. In the result, separated centrifugation with histopaque showed the significantly lower number of red blood cells than other groups. The 2-step centrifugation showed the significantly higher number of white blood cells than other groups, while it contained the highest concentration of red blood cells among three groups. In the 2-step centrifugation, separated centrifugation and separated centrifugation with histopaque, platelets were concentrated 4.5, 5.3 and 5.6 times, respectively. And no significant difference of the platelet concentration between the three groups was found. This study demonstrated that separated centrifugation using histopaque was the best method for platelet rich plasma preparation because of the proper amount of platelets and the separation of red blood cells from platelet rich plasma.

Assessment of Canine Autologous Conditioned PlasmaTM Cellular and Transforming Growth Factor-β1 Content

To evaluate (1) the cellular composition of canine ACP™ including using two different preparation protocols with variations on centrifugation time, (2) the effect of different activation protocols on the transforming growth factor (TGF)-β1 content in the ACP, and (3) patient factors that might influence platelet concentration of the ACP.

ACP was made with blood from 15 dogs using a manufacturer-recommended protocol^[1]. Each ACP sample was divided into three aliquots that were activated with calcium chloride (CaCl₂), human γ-thrombin (HGT), or not activated. TGF-β1 was quantified in each aliquot using an ELISA and comparisons among activation protocols were performed using a Skillings-Mack test. Correlations between platelet and TGF-β1 concentration were assessed with a Pearson correlation coefficient. ACP was subsequently prepared from an additional 17 dogs using a slightly modified centrifugation protocol and cellular composition was assessed. Effects of dog age, body weight, and hematocrit were assessed for their potential impact on ACP platelet concentration using a multiple linear regression analysis.

The mean increase in platelet concentration in the ACP above that in the whole blood was 1.2× (±std 0.62) and leukocyte concentration was a mean of 26% (0.37) that in the whole blood using the standard protocol. There was a significant (p < 0.01) effect of activation on TGF-β1 concentrations with mean concentrations of 4,538 (2,317), 14,948 (13,784), and 14,096 (15,210) pg/ml in aliquots that were not activated or were activated with thrombin or CaCl₂ respectively. There were significant correlations between the platelet concentration and TGF-β1 concentration in aliquots that were activated with either thrombin (r = 0.66; p < 0.01) or CaCl₂ (r = 0.86, p < 0.0001). The mean increase in platelet concentration was 1.4× (0.62) and the leukocyte concentration was 0.28× (0.13) that in whole blood using the modified ACP preparation protocol. Dog age, body weight, and hematocrit were not significant predictors of ACP platelet concentration.

These data show that on average this preparation protocol produces a mildly platelet-concentrated, leukoreduced platelet-rich plasma. Intentional activation had a significant effect on TGF-β1 concentrations with use of both CaCl₂ and thrombin resulting in higher TGF-β1 concentrations than that obtained in samples that are not activated.

Ultrasonographic Findings in 41 Dogs Treated with Bone Marrow Aspirate Concentrate and Platelet-Rich Plasma for a Supraspinatus Tendinopathy: A Retrospective Study

Objective

To report sonographic findings for dogs with a supraspinatus tendinopathy (ST) treated with an ultrasound-guided intratendinous injection of bone marrow aspirate concentrate (BMAC) and platelet-rich plasma (PRP).

Methods

Medical records for dogs diagnosed with an ST and treated with a BMAC-PRP injection were reviewed. Data collected included patient signalment, radiographic findings at the time of initial evaluation, and sonographic findings, including cross-sectional area (CSA), fiber pattern, and echogenicity.

Results

Of 70 records reviewed, 41 met the inclusion criteria. Mean CSA of the supraspinatus tendon decreased by 0.06 cm² between baseline and 45 days post-treatment (p = 0.0025), and 0.09 cm² between baseline and 90 days post-treatment (p < 0.0001). Analysis of CSA in dogs with a unilateral ST at baseline revealed a difference of 0.08 cm² between the affected and unaffected tendon at baseline, with the affected tendon measuring larger than the contralateral tendon (p < 0.0001). This difference became statistically insignificant by 45 days after treatment (u₁-u₀ = 0.04 cm², p = 0.2855) and remained so 90 days post-treatment (u₁-u₀ = 0.03 cm², p = 0.1910). In most cases (90.6%), the fiber pattern and echogenicity was considered improved 90 days post treatment. In a minority of these cases (13.8%) the fiber pattern and echogenicity abnormalities were considered resolved.

Conclusions

Using qualitative and quantitative sonographic measures, BMAC-PRP was associated with an improvement in supraspinatus tendon size, fiber pattern, and echogenicity. Given the protracted nature of tendon healing, long-term evaluation may reveal continued improvements in chronic structural changes not captured during the current study. Functional studies are required to evaluate the clinical benefits of BMAC-PRP in the treatment of STs in dogs.

Clinical significance

An ST is a common contributor to forelimb lameness in dogs and remains notoriously difficult to treat. Previous studies have been associated with inconsistent treatment outcomes. In the current study, BMAC-PRP is investigated as a minimally invasive treatment option, revealing positive sonographic results.

Study of a Two-Step Centrifugation Protocol for Concentrating Cells and Growth Factors in Bovine Platelet-Rich Plasma

There is a lack of information about the methods used for bovine platelet-rich plasma (PRP)/platelet-rich gel (PRG) procurement, including information on platelet (PLT), white blood cell (WBC) in PRP, and growth factor release from PRG supernatants. The aims of this study were to compare and to correlate the PLT, WBC, transforming growth factor beta-1 (TGF-β₁), and platelet-derived growth factor BB (PDGF-BB) concentrations in bovine whole blood, plasma, and four PRP layers and their respective PRG supernatants: A and B (obtained by a single centrifugation tube method at 720g/5 min) and C and D (obtained by a double centrifugation tube method, by using two centrifugation episodes at 720g/5 min). PLT and WBC counts were significantly higher in PRP-C, followed by whole blood, PRP-A, PRP-B, and PRP-D. TGF-β₁ concentrations were significantly higher in PRG-B supernatants and its correspondent PRP-B lysate when compared to the other PRG supernatants and plasma. Supernatants from PRG-A, PRG-B, and PRG-D had equivalent TGF-β₁ concentrations. PDGF-BB concentrations were not statistically different between the hemoderivatives. Significant Pearson correlations were noted between PLT counts and WBC counts (0.8) and between PLT counts and PLT distribution width (0.6). Further studies should be performed to assess the potential clinical applications of these PRPs.

Influence of Cellular Composition and Exogenous Activation on Growth Factor and Cytokine Concentrations in Canine Platelet-Rich Plasmas

OBJECTIVE

The purposes of this study were to (1) evaluate correlations among platelet, leukocyte, growth factor, and cytokine concentrations in canine platelet-rich plasmas (PRPs) produced from five different canine PRP-concentrating systems and (2) compare the effects of different activation protocols on platelet activation and growth factor release from one of these PRPs.

METHODS

PRP was made using blood from 15 dogs and each of 5 different PRP systems in a cross-over design. Complete blood counts were performed to quantify platelet and leukocyte concentrations. PRPs were activated, or not, according to manufacturer instructions, and transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-BB (PDGF-BB), vascular endothelial growth factor, and tumor necrosis factor-alpha (TNF-α) were quantified. Differences among platelet, leukocyte, and growth factor concentration were compared among the different systems. Correlations between platelet and anabolic growth factor concentrations were assessed. Subsequently, PRP was made from 12 additional dogs using one of the devices. Each PRP was divided into three aliquots that were activated with calcium chloride (CaCl₂), human γ-thrombin (HGT), or not activated. Expression of CD62P and platelet-bound fibrinogen (CAP1) was quantified for each activation group. Concentrations of TGF-β1, PDGF-BB, and TNF-α were also quantified for each activation group and a fourth group that was frozen/thawed. Differences among activation groups were assessed by a Friedman test.

RESULTS

There were statistically significant differences among the PRPs made with difference devices with regard to platelet, leukocyte, TGF-β1, and PDGF-BB concentrations (p < 0.0001). There were weak to moderate correlations (R² = 0.07-0.58) between platelet and anabolic growth factor concentrations but it appeared that activation had a greater effect on growth factor concentration than did cellular composition. Intentional platelet activation significantly increased CD62P and CAP1 expression as well as TGF-β1 and PDGF-BB concentrations in the one PRP in which all activation methods were assessed. Activation with HGT resulted in the greatest platelet activation, and CaCl₂ and freeze/thaw elicited moderate increases in either growth factor release or CD62P and CAP1 expression.

CONCLUSION

There are positive correlations between platelet and anabolic growth factor concentrations in canine PRPs. However, intentional platelet activation has a greater effect on growth factor delivery than platelet concentration. Thrombin provides more robust activation than CaCl₂.