Clinical Evaluation of Intralesional Injection of Platelet-Rich Plasma for the Treatment of Proximal Suspensory Ligament Desmitis in Horses

Musculoskeletal Injury and Illness Patterns in British Eventing Horses: A Descriptive Study

There has been little investigation into the health patterns of the eventing horse population outside veterinary clinics. To target health problems in the eventing horse population, it is important to determine the relative impact of different health problems. The objectives were to describe the prevalence and patterns of lameness/illness in registered British eventing horses. An online survey was released for all horses registered with British eventing in 2018. Data were collated and descriptive analyses undertaken. A total of 1677 surveys were completed, among which 49.4% reported a previous lameness/musculoskeletal problem, 26% being in the previous six months. The most frequently reported musculoskeletal problems were in the foot (421), joints (382), wounds (340), back (333), ligament (205), tendon (213), bones (140) and muscles (135). The most frequent non-musculoskeletal problems related to the skin (183), gastric ulceration (173), colic (145) and infection (88). Injuries to the hoof sole/muscles/tendons were most frequently sustained in competition, suspensory ligament/splint bone/stifle/tarsal injuries were more frequently sustained in training and abscess/foot penetration at rest. DDFT injuries were most frequently out of training for >12 months, SDFT/stifle/suspensory ligament for <12 months, tendon sheath/splint bone for <3 months and tarsal/sole bruising/abscess for <2 weeks. A greater understanding of injuries/illnesses frequently sustained could be useful for veterinarians working with event horses.

Freeze-drying protocols and methods of maintaining the in-vitro biological activity of horse platelet lysate

Platelet lysate, derived from platelets, are valuable biological products rich in bioactive molecules. Their use promotes tissue healing and modulates inflammation. However, maintaining the stability and bioactivity of platelet lysate is challenging since they degrade rapidly at room temperature. This study focused on the possibility to confer enhanced stability to freeze-dried equine platelet lysate as an alternative to platelet-rich plasma (PRP). Platelet lysate (PL) was derived from PRP and freeze-dried either as such or using various adjuvants. Primary cell cultures of porcine Vascular Wall-Mesenchymal Stem Cells were treated with different PL formulations, and cell viability was assessed using an MTT assay. Overall, the addition of PL significantly improved cell viability as compared to controls without growth factor supplementation or with foetal bovine serum. Notably, the freeze-drying process maintained the effectiveness of the PL for at least a week. Furthermore, the study revealed that varying the horse as the source of PL could yield varying effects on cell viability. Detailed freeze-drying protocols were established, including freezing, primary drying and secondary drying phases, and the type of adjuvant. This study demonstrated the potential of freeze-dried equine PL as a viable alternative to PRP and highlighted the importance of precise freeze-drying protocols and adjuvants for standardization. Equine PL showed promise for medical treatment in horses, offering advantages such as extended shelf life, ease of handling, and reduced transportation costs, with the potential for broadened therapeutic usage.

Outcome following local injection of a liquid amnion allograft for treatment of equine tendonitis or desmitis – 100 cases

Background

Tendon and ligament injuries are significant causes of loss of use and early retirement in performance horses. Amniotic fluid and tissue are excellent sources of growth factors and cytokines important in tendon and ligament healing. Thus, an equine-origin liquid amnion allograft (ELAA) may be beneficial in the treatment of equine tendonitis and desmitis. Objectives of this study were to report the outcome achieved (i.e. ability to return to work) for horses diagnosed with tendonitis or desmitis lesions treated with local injection of ELAA and to compare these outcomes to those reported for other regenerative medicine modalities.

Methods

A prospective, multi-center, non-blinded clinical trial was conducted. Equine veterinarians at 14 sites were selected to participate in the data collection for the trial. Criterion for inclusion was a horse presenting with lameness which was attributed to tendonitis or desmitis by diagnostic anesthesia and/or imaging. These horses were subsequently treated by local injection of the lesion with ELAA by the attending veterinarian. Standardized questionnaires describing each horse’s signalment, discipline, ability to return to work, and any adverse events were completed and submitted by the attending veterinarian following a minimum of six months of follow-up. The current literature was reviewed to identify clinical studies reporting outcomes of equine tendonitis/desmitis lesions treated with other regenerative therapies. Contingency table analyses were performed comparing outcomes.

Results

Questionnaires for 100 horses with 128 tendonitis and desmitis lesions met the inclusion criteria. Of these, 72 horses with 94 lesions returned to or exceeded their original level of work, 10 horses with 13 lesions returned to work but could not perform to previous standards, and 18 horses with 20 lesions did not return to work as a result of the injury. No differences were observed when outcome of horses treated with ELAA were compared to those of similar studies using other regenerative therapies.

Conclusions

Treatment of tendonitis and desmitis lesions by local injection of ELAA resulted in similar outcomes for horses returning to previous level of performance as other regenerative modalities such as mesenchymal stem cells, platelet-rich plasma, and autologous conditioned serum; however, blinded placebo-controlled studies are indicated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03480-5.

Use of autologous products for the treatment of joint and soft tissue disease in horses: A systematic review

BACKGROUND

Soft tissue injuries and joint disease are the predominate causes of lameness in the equine athlete and these pathologies carry a guarded prognosis for a return to previous performance. Recently the use of autologous products has become more widespread as a treatment in equine sports medicine. However, the efficacy of these products is yet to be fully established.

OBJECTIVE

To evaluate the current published evidence base regarding the efficacy of autologous products in soft tissue injuries and joint disease.

METHODS

A systematic review of English articles using MEDLINE, EMBASE and Web of Science databases from 1980 to 2017. The search strategy identified 1594 papers for review.

RESULTS

Fifty-eight papers were included in this review, 28 of which were randomised controlled trials. Significant benefit was reported under several parameters, most notably in the use of autologous chondrocytes in artificially induced cartilage defects on histology. One paper documented a significant clinical response under lameness examination.

CONCLUSION

The current literature shows that the treatment of soft tissue injury and cartilage disease with autologous products is safe and that the use of some products can give significant benefit on some outcome measures. True clinical significance is yet to be demonstrated with any product.

The Use of Platelet-Rich Plasma for Treatment of Tenodesmic Lesions in Horses: A Systematic Review and Meta-Analysis of Clinical and Experimental Data

The use of platelet-rich plasma (PRP) to enhance tenodesmic lesion healing has been questioned over the years. The aim of this study was to evaluate current literature to establish the effectiveness of PRP for treating tenodesmic lesions through a systematic review, in accordance with the PRISMA guidelines, and a meta-analysis. Studies comparing PRP with placebo or other treatments for horses with tenodesmic injuries or evaluated PRP effect on tendon and ligament explants were included. Outcomes were clinical, ultrasound, histologic, molecular evaluation, and adverse effects. Two authors independently extracted data and assessed each study's risk of bias. Treatment effects were evaluated using risk ratios for dichotomous data, together with 95% CI. Data were pooled using the random-effects model. The quality of the evidence for each outcome was assessed using GRADE criteria. Twenty-four trials met inclusion criteria for systematic review, while fifteen studies were included in the meta-analysis. Results showed no significant differences in the outcomes between PRP and control groups. Finally, there is no definitive evidence that PRP enhances tendons and ligaments healing. Therefore, there is a need for more controlled trials to draw a firmer conclusion about the efficacy of PRP as a treatment for tenodesmic lesions in the horse.

Prospective randomized comparison of platelet rich plasma to extracorporeal shockwave therapy for treatment of proximal suspensory pain in western performance horses

Proximal suspensory desmitis (PSD) is a frequent cause of lameness in the performance horse. Extracorporeal shockwave therapy (EST) and platelet rich plasma (PRP) have become common treatments for PSD yet clinical data on efficacy is limited. The main objective of this randomized, prospective clinical study was to compare long-term effectiveness of EST and PRP in Western performance horses. One hundred horses with lameness localized to the proximal suspensory ligament received treatment with either PRP or EST following baseline ultrasonographic evaluation. A veterinarian and agent evaluated the horses for lameness independently four days following the first treatment and long-term follow up was obtained from the agent at six and twelve months. Four days post treatment, horses treated with EST had significantly greater lameness improvement compared to PRP. At one-year horses with less severe baseline ultrasound changes (grades 0-1) appeared to respond better (degree of lameness) with EST treatment whereas horses with more severe ultrasound changes (grade 2) responded better to PRP. Horses with baseline lameness graded 1 or 2 were 5.1 times more likely to be back in work at 1 year compared to those presenting with grade 3 or 4. EST treatment was associated with going back to work 3.8 times more at one year compared to PRP independent of baseline ultrasound score. Both PRP and EST can be expected to yield favorable therapeutic responses in Western performance horses with lameness localized to the proximal suspensory region. Baseline ultrasound may guide treatment selection.

Assessment of Noninvasive Low-Frequency Ultrasound as a Means of Treating Injuries to Suspensory Ligaments in Horses: A Research Paper

Therapeutic ultrasound is a noninvasive technique, which is well tolerated by horses, does not need sedation, and can easily be performed in a routine clinical setting. Twenty-three client-owned sport horses were recruited at Clinica Equina San Biagio and included in this case study. Treatment of the injured suspensory ligament apparatus was administered using an EQ Pro, low-frequency therapeutic unit (38 kHz). The noninvasive treatment consisted of massaging the injured area in combination with a traditional ultrasound gel while maintaining the head of the device in direct contact with the injured area. The results indicate that 20 of the 23 horses in this study benefitted from EQ Pro treatment and, following a routine rehabilitation program, returned to competition status: a success rate of 87%. Furthermore, treatment duration was 3.3 ± 0.4 weeks on average, with a healthy outcome as assessed by ultrasound at 6.8 ± 1.9 weeks. Among the 23 horses in this study, 65% of them benefitted from EQ Pro treatment of a duration of just ≤3.3 weeks. It is concluded that EQ Pro therapy is a promising and effective form of treatment for horses with suspensory ligament injury. It is furthermore rapid and easy to use in the Equine Veterinary Clinic setting and does not require sedation. Future studies should now focus on the mechanisms by which this new treatment activates the healing process of the suspensory ligaments of injured horses.

Extracorporeal Shockwave Therapy Increases Growth Factor Release from Equine Platelet-Rich Plasma In Vitro

Introduction

Extracorporeal shockwave therapy (ESWT) and platelet-rich plasma (PRP) are common treatments for soft tissue injuries in horses. Shockwave triggers cell specific responses to promote healing. Growth factors released from PRP also promote healing. It has been hypothesized that greater growth factor release would amplify the healing process. The combination of ESWT and PRP could promote healing in injured tendons and ligaments in the horse. The objective of this study was to determine if application of shockwaves to PRP samples increases the concentration of transforming growth factor-β₁ (TGF-β₁) and platelet-derived growth factor ββ (PDGF-ββ) released from the platelets in vitro.

Materials and methods

PRP was produced from blood drawn from six horses. The PRP from each horse was exposed to the following treatments: (1) positive control (freeze-thaw cycle), (2) untreated negative control, or shockwaves with either (3) a "standard probe" (ESWT-S) with a 2 cm focal width and medium energy density or (4) a "power probe" (ESWT-P) with a 1 cm focal width and high energy density. After each treatment, the samples were centrifuged, and the supernatant was harvested. The supernatant was then used for growth factor quantification via commercially available ELISA kits for TGF-β₁ and PDGF-ββ.

Results

Concentrations of TGF-β₁ and PDGF-ββ in PRP that underwent a freeze-thaw cycle were significantly increased compared with all other treatments. Both ESWT-S and ESWT-P resulted in significantly increased TGF-β₁ concentrations, 46 and 33%, respectively, when compared with the negative control. Both ESWT-S and ESWT-P resulted in significantly increased PDGF-ββ concentrations, 219 and 190%, respectively, when compared with the negative control.

Discussion

These data indicate that the application of ESWT to PRP increases the expression of growth factors in vitro. This suggests that the combination therapy of local PRP injection followed by ESWT may stimulate release of growth factors from platelets after they have been injected into the area of injury.

Conclusion

The combination of PRP and ESWT might result in synergism of two modalities previously utilized individually for tendon and ligament injuries in horses.

Tenogenically Induced Allogeneic Mesenchymal Stem Cells for the Treatment of Proximal Suspensory Ligament Desmitis in a Horse

Suspensory ligament injuries are a common injury in sport horses, especially in competing dressage horses. Because of the poor healing of chronic recalcitrant tendon injuries, this represents a major problem in the rehabilitation of sport horses and often compromises the return to the initial performance level. Stem cells are considered as a novel treatment for different pathologies in horses and humans. Autologous mesenchymal stem cells (MSCs) are well known for their use in the treatment of tendinopathies; however, recent studies report a safe use of allogeneic MSCs for different orthopedic applications in horses. Moreover, it has been reported that pre-differentiation of MSCs prior to injection might result in improved clinical outcomes. For all these reasons, the present case report describes the use of allogeneic tenogenically induced peripheral blood-derived MSCs for the treatment of a proximal suspensory ligament injury. During conservative management for 4 months, the horse demonstrated no improvement of a right front lameness with a Grade 2/5 on the American Association of Equine Practitioners (AAEP) scale and a clear hypo-echoic area detectable in 30% of the cross sectional area. From 4 weeks after treatment, the lameness reduced to an AAEP Grade 1/5 and a clear filling of the lesion could be noticed on ultrasound. At 12 weeks (T₄) after the first injection, a second intralesional injection with allogeneic tenogenically induced MSCs and platelet-rich plasma was given and at 4 weeks after the second injection (T₅), the horse trotted sound under all circumstances with a close to total fiber alignment. The horse went back to previous performance level at 32 weeks after the first regenerative therapy and is currently still doing so (i.e., 20 weeks later or 1 year after the first stem cell treatment). In conclusion, the present case report demonstrated a positive evolution of proximal suspensory ligament desmitis after treatment with allogeneic tenogenically induced MSCs.

Immunohistochemical Expression of Collagens in the Skin of Horses Treated with Leukocyte-Poor Platelet-Rich Plasma

This study evaluated the immunohistochemical expression of type I (COL I) and III (COL III) collagens during the healing process of skin treated with leukocyte-poor platelet-rich plasma (LP-PRP). Seven healthy gelding crossbred horses aged 16 to 17 years were used. Two rectangle-shaped wounds were created surgically in the right and left gluteal regions. Twelve hours after wound induction, 0.5 mL of the LP-PRP was administered in each edge of the wounds of one of the gluteal regions. The contralateral region was used as control (CG). Three samples were obtained: after wound induction (T0), 14 days (T1) of healing process, and after complete closure of the skin (T2). The normal skin (T0) showed strong staining for type III and I collagen in papillary and reticular dermis, respectively. In the scar of the treated group, COL III showed important (p < 0.05) increase in immunoreaction in T2 compared with T1. The administration of a single dose of LP-PRP 12 h after induction of wound in horses does not influence formation of collagens I and III. However, the intense labeling for COL III suggests that the tissue was still weak during the macroscopic closure of the wound, demonstrating that healing was not completely finished.