Gene Therapy Using Plasmid DNA Encoding VEGF164 and FGF2 Genes: A Novel Treatment of Naturally Occurring Tendinitis and Desmitis in Horses

A method for detecting gene doping in horse sports without DNA extraction

Gene doping is prohibited in horse sports and can involve the administration of exogenous genes, called transgenes, to postnatal animals. Quantitative polymerase chain reaction (qPCR) methods have been developed to detect gene doping; however, these generally require DNA extraction from the plasma prior to qPCR. In this study, we developed two methods, direct droplet digital PCR (ddPCR) and nested ddPCR, to detect the equine erythropoietin (EPO) transgene without DNA extraction. Direct ddPCR used pretreated plasma and PCR to detect the EPO transgene spiked at 10 copies/μL. Nested ddPCR utilised pre-amplification using nontreated plasma, purification of PCR products and PCR to detect the EPO transgene spiked at 1 copy/μL in plasma. These methods successfully detected the EPO transgene after intramuscular injection into horses. Since each method has different detection sensitivity, the combined use of direct ddPCR for screening and nested ddPCR for confirmation may complement each other and prevent the occurrence of false positives, allowing the reliable detection of gene-doped substances. One advantage of these methods is the small amount of sample required, approximately 2.2-5.0 μl, owing to the lack of a DNA extraction step. Therefore, these tests could be applied to small volume samples as an alternative to conventional gene doping tests.

Gene doping detection in the era of genomics

Recent progress in gene editing has enabled development of gene therapies for many genetic diseases, but also made gene doping an emerging risk in sports and competitions. By delivery of exogenous transgenes into human body, gene doping not only challenges competition fairness but also places health risk on athletes. World Anti-Doping Agency (WADA) has clearly inhibited the use of gene and cell doping in sports, and many techniques have been developed for gene doping detection. In this review, we will summarize the main tools for gene doping detection at present, highlight the main challenges for current tools, and elaborate future utilizations of high-throughput sequencing for unbiased, sensitive, economic and large-scale gene doping detections. Quantitative real-time PCR assays are the widely used detection methods at present, which are useful for detection of known targets but are vulnerable to codon optimization at exon-exon junction sites of the transgenes. High-throughput sequencing has become a powerful tool for various applications in life and health research, and the era of genomics has made it possible for sensitive and large-scale gene doping detections. Non-biased genomic profiling could efficiently detect new doping targets, and low-input genomics amplification and long-read third-generation sequencing also have application potentials for more efficient and straightforward gene doping detection. By closely monitoring scientific advancements in gene editing and sport genetics, high-throughput sequencing could play a more and more important role in gene detection and hopefully contribute to doping-free sports in the future.

Viable tendon neotissue from adult adipose-derived multipotent stromal cells

Background: Tendon healing is frequently prolonged, unpredictable, and results in poor tissue quality. Neotissue formed by adult multipotent stromal cells has the potential to guide healthy tendon tissue formation. Objectives: The objective of this study was to characterize tendon neotissue generated by equine adult adipose-derived multipotent stromal cells (ASCs) on collagen type I (COLI) templates under 10% strain in a novel bioreactor. The tested hypothesis was that ASCs assume a tendon progenitor cell-like morphology, express tendon-related genes, and produce more organized extracellular matrix (ECM) in tenogenic versus stromal medium with perfusion and centrifugal fluid motion. Methods: Equine ASCs on COLI sponge cylinders were cultured in stromal or tenogenic medium within bioreactors during combined perfusion and centrifugal fluid motion for 7, 14, or 21 days under 10% strain. Viable cell distribution and number, tendon-related gene expression, and micro- and ultra-structure were evaluated with calcein-AM/EthD-1 staining, resazurin reduction, RT-PCR, and light, transmission, and scanning electron microscopy. Fibromodulin was localized with immunohistochemistry. Cell number and gene expression were compared between culture media and among culture periods (p < 0.05). Results: Viable cells were distributed throughout constructs for up to 21 days of culture, and cell numbers were higher in tenogenic medium. Individual cells had a round or rhomboid shape with scant ECM in stromal medium in contrast to clusters of parallel, elongated cells surrounded by highly organized ECM in tenogenic medium after 21 days of culture. Transcription factor, extracellular matrix, and mature tendon gene expression profiles confirmed ASC differentiation to a tendon progenitor-like cell in tenogenic medium. Construct micro- and ultra-structure were consistent with tendon neotissue and fibromodulin was present in the ECM after culture in tenogenic medium. Conclusion: Long-term culture in custom bioreactors with combined perfusion and centrifugal tenogenic medium circulation supports differentiation of equine adult ASCs into tendon progenitor-like cells capable of neotissue formation.

Bevacizumab Efficiently Inhibits VEGF-Associated Cellular Processes in Equine Umbilical Vein Endothelial Cells: An In Vitro Characterization

Anti-VEGF agents were found to have clinical implications for the successful treatment of vascular-driven diseases in humans. In this study, a detailed biological characterization of bevacizumab in a variety of in vitro assays was carried out to determine the effect of bevacizumab on equine umbilical vein endothelial cells (EqUVEC). EqUVECs were harvested from umbilical cords of clinically healthy horses and exposed to different concentrations (1, 2, 4, 6, 8 mg/mL) of bevacizumab (Avastin®). Assays concerning the drug's safety (cell viability and proliferation assay) and efficacy (cell tube formation assay, cell migration assay, and Vascular endothelial growth factor (VEGF) expression) were carried out reflecting multiple cellular processes. Bevacizumab significantly decreased VEGF expression at all concentrations over a 72 h period. No cytotoxic effect of bevacizumab on EqUVECs was observed at concentrations of 4 mg/mL bevacizumab or lower. Incubated endothelial cells showed delayed tube formation and bevacizumab efficiently inhibited cell migration in a dose-dependent manner. Bevacizumab potently inhibits VEGF-induced cellular processes and could be a promising therapeutic approach in vascular-driven diseases in horses.

Administration and detection of gene therapy in horses: A systematic review

Gene therapy uses genetic modification of cells to produce a therapeutic effect. Defective or missing genes can be repaired or replaced, or gene expression can be modified using a variety of technologies. Repair of defective genes can be achieved using specialized gene editing tools. Gene addition promotes gene expression by introducing synthetic copies of genes of interest (transgenes) into cells where they are transcribed and translated into therapeutic proteins. Protein production can also be modified using therapies that regulate gene expression. Gene therapy is currently prohibited in both human and equine athletes because of the potential to induce production of performance-enhancing proteins in the athlete's body, also referred to as "gene doping." Detection of gene doping is challenging and necessitates development of creative, novel analytical methods for doping control. Methods for detection of gene doping must be specific to and will vary depending on the type of gene therapy. The purpose of this paper is to present the results of a systematic review of gene editing, gene therapy, and detection of gene doping in horses. Based on the published literature, gene therapy has been administered to horses in a large number of experimental studies and a smaller number of clinical cases. Detection of gene therapy is possible using a combination of PCR and sequencing technologies. This summary can provide a basis for discussion of appropriate and inappropriate uses for gene therapy in horses by the veterinary community and guide expansion of methods to detect inappropriate uses by the regulatory community.

The Functions and Mechanisms of Basic Fibroblast Growth Factor in Tendon Repair

Tendon injury is a disorder of the musculoskeletal system caused by overuse or trauma, which is characterized by pain and limitations in joint function. Since tendon healing is slowly and various treatments are generally ineffective, it remains a clinically challenging problem. Recent evidences suggest that basic fibroblast growth factor (bFGF) not only plays an important role in tendon healing, but also shows a positive effect in laboratory experimentations. The purpose of this review is to summarize the effects of bFGF in the tendon healing. Firstly, during the inflammatory phase, bFGF stimulates the proliferation and differentiation of vascular endothelial cells to foster neovascularization. Furthermore, bFGF enhances the production of pro-inflammatory factors during the early phase of tendon healing, thereby accelerating the inflammatory response. Secondly, the cell proliferation phase is accompanied by the synthesis of a large number of extracellular matrix components. bFGF speeds up tendon healing by stimulating fibroblasts to secrete type III collagen. Lastly, the remodeling phase is characterized by the transition from type III collagen to type I collagen, which can be promoted by bFGF. However, excessive injection of bFGF can cause tendon adhesions as well as scar tissue formation. In future studies, we need to explore further applications of bFGF in the tendon healing process.

Direct sequence confirmation of qPCR products for gene doping assay validation in horses

The misuse of gene therapy by the introduction of transgenes via plasmid or viral vectors as a doping agent is an increasing concern in human and animal sports, not only in consideration to fair competition but also potential detrimental effects to welfare. Doping events can be detected by PCR amplification of a transgene-specific region of DNA. The quantitative nature of real time qPCR makes it particularly suited to confirmatory investigations where precise limits of detection can be calculated. To fully validate a qPCR experiment, it is highly desirable to confirm the identity of the amplicon. Although post-PCR techniques such as melt curve and fragment size analysis can provide strong evidence that the amplicon is as expected, sequence identity confirmation may be beneficial as part of regulatory proceedings. We present here our investigation into two alternative processes for the direct assessment of qPCR products for five genes using next-generation sequencing: ligation of sequence-ready adapters to qPCR products, and qPCR assays performed with primers tailed with Illumina flow cell binding sites. To fully test the robustness of the techniques at concentrations required for gene doping detection, we also calculated a putative limit of detection for the assays. Both ligated adapters and tailed primers were successful in producing sequence data for the qPCR products without further amplification. Ligated adapters are preferred, however, as they do not require re-optimisation of existing qPCR assays.

The Role of Vascular Endothelial Growth Factor in Tendon Healing

Angiogenesis is crucial to facilitate tendon healing, such as delivering oxygen and nutrients, removing waste products, and controlling immune responses. Vascular endothelial growth factor (VEGF) is one of the most vital angiogenic factors that regulate blood vessel formation in tendon healing. Recently, biological therapies, including the application of exogenous VEGF, have been attracting increasing attention. However, at present, the effect of the application of exogenous VEGF in tendon healing is controversial, as the role of endogenous VEGF in tendons has also not been fully elucidated. This article will summarize the role of both endogenous and exogenous VEGF in tendon healing and discuss possible reasons for the controversy. The present review shows that tendon repair is facilitated only by proper angiogenesis and VEGF at the early stage, whereas the persistent high VEGF expression and prolonged presence of blood vessels may impair tendon repair at a later stage.

ANOVA-Based Analysis of Early Blood Transfusions on Hemodynamics with Severely Injured Trauma Using Bedside Ultrasound Imaging

The focus of the study was to quantitatively analyze the influence of early massive blood transfusions (MBTs) on the hemodynamics and prognostic living quality of patients with severely injured trauma. 114 patients with severely injured trauma were enrolled into MBT group (67 cases) and nonmassive blood transfusions (NBT) group (47 cases) according to whether they accepted MBTs within 24 hours after the admission. All patients had bedside ultrasound technology scanning. Furthermore, the indexes were calculated for inferior vena cava (IVC), peripheral arteries, and heart. The prognostic deaths were recorded. It was found that, in the MBT group, the mortality was lower (7.55% vs. 24.23%) (P < 0.05), and these indexes were higher for the IVC expansion (IVCE), the respiration variation index (RVI) of IVC (ΔIVC2), the peak flow velocity RVI of brachial artery (ΔVpeakBA), femoral artery (ΔVpeakFA), left ventricular outflow tract (ΔVpeakL), and aorta (ΔVpeakAO), as well as peak flow velocity time integral RVI of aorta (ΔVTIAO) (P < 0.05). In conclusion, early MBTs can elevate survival rate and prognostic living quality and alleviate the atrophy degree of IVC, peripheral artery, and blood vessel of patients with severely injured trauma. Furthermore, bedside ultrasound scanning demonstrated superb capabilities in quantitatively displaying hemodynamics and outcomes of MBTs of patients with severely injured trauma.

Screening for gene doping transgenes in horses via the use of massively parallel sequencing

Throughout the history of horse racing, doping techniques to suppress or enhance performance have expanded to match the technology available. The next frontier in doping, both in the equine and human sports areas, is predicted to be genetic manipulation; either by prohibited use of genome editing, or gene therapy via transgenes. By using massively-parallel sequencing via a two-step PCR method we can screen for multiple doping targets at once in pooled primer sets. This method has the advantages of high scalability through combinational indexing, and the use of reference standards with altered sequences as controls. Custom software produces transgene-specific amplicons from any Ensembl-annotated genome to facilitate rapid assay design. Additional scripts batch-process FASTQ data from experiments, automatically quality-filtering sequences and assigning hits based on discriminatory motifs. We report here our experiences in establishing the workflow with an initial 31 transgene and vector feature targets. To evaluate the sensitivity of parallel sequencing in a real-world setting, we performed an intramuscular (IM) administration of a control rAAV vector into two horses and compared the detection sensitivity between parallel sequencing and real-time qPCR. Vector was detected by all assays on both methods up to 79 h post-administration, becoming sporadic after 96 h.

The treatment of articular cartilage injuries with mesenchymal stem cells in different animal species

One of the major problems observed in veterinary practice is articular cartilage injuries in animals. In terms of agriculture, it leads to their culling from the herd, even if they are highly productive animals. With companion animals, owners usually have to decide between euthanasia or long-term sometimes lifelong treatment of the injury by a veterinarian. The use of mesenchymal stem cells (MSCs) for the treatment of cartilage injury in veterinary medicine is based on the good results observed in preclinical studies, where large animals have been used as experimental models to study the regenerative activity of MSCs. According to the literature, MSCs in veterinary medicine have been used to treat cartilage injury of dogs and horses, whereas sheep and goats are generally models for reproducing the disease in preclinical experimental studies.

Whole-genome resequencing using genomic DNA extracted from horsehair roots for gene-doping control in horse sports

Gene doping is prohibited in horseracing and equestrian sports. In previous studies, we developed non-targeted transgene and genome editing detection methods based on whole genome resequencing (WGR) using genomic DNA extracted from whole blood. In this study, we aimed to develop a WGR method using DNA extracts from hair roots. Hair roots are a preferred substrate because their collection is less invasive than blood collection. Hair is also easier to store for long periods of time. Although almost all genomic DNA extracted from hair root samples stored for years at room temperature was degraded, the quality of genomic DNA from samples stored for years at refrigerated temperatures (4–8°C) was maintained. High-molecular-weight genomic DNA was isolated from hair roots using a magnetic silica beads method of extraction, enabling WGR from horsehair root extracts. Nucleotide sequencing results and numbers of single-nucleotide polymorphisms and insertions/deletions concurred with those previously reported for WGR of DNA extracted from whole blood. Therefore, we consider that storing hair samples at refrigerated temperatures prevents degradation of DNA, allowing the detection of gene doping in these samples based on WGR. It is likely this finding will also have a deterrent effect, as it is now possible to test horses with archived samples even if they or their parents are deceased. To our knowledge, this is the first report employing WGR on horsehair roots stored for a long term.

Extracellular Vesicles: New Perspectives of Regenerative and Reproductive Veterinary Medicine

Extracellular vesicles are released by all cell types including stem cells. Stem cell-released extracellular vesicles have therapeutic effects similar to those of their parent cells and have regenerative effects in tissues. They also have an immunomodulating effect when down-regulating some proinflammatory factors, without exerting effects on cell proliferation, modulating angiogenesis or altering cellular functions in recipient cells. Modern veterinary research explores vesicles and creates or advances methods of using them in regenerative and reproductive medicine, applications of these technologies are under development.

Application of gene therapy in the treatment of superficial digital flexor tendon injury in horses

Background:

Tendon injuries are one of the most common causes of orthopedic disorders in horses. Such injuries involve a long course of treatment and recovery. The most promising method of treating these injuries is the use of recombinant proteins and gene therapy.

Aim:

In this work, we evaluated the therapeutic efficacy of plasmid DNA (pDNA) containing two species-specific coding sequences, i.e. vascular endothelial growth factor 164 (VEGF164) and fibroblast growth factor 2 (FGF2), in the treatment of severe damage to the tendon of the superficial digital flexor.

Methods:

A pDNA construct was used to restore the damaged superficial digital flexor tendon in the horse.

Results:

This study showed that the administration of pDNA encoding VEGF164 and FGF2 genes at the injury area increased the regenerative activities of the damaged tendon.

Conclusion:

This study shows the therapeutic properties of genetic constructs (pDNA) and contributes to the advancements in the use of these therapies.

Endothelial cells and angiogenesis in the horse in health and disease-A review

The cardiovascular system is the first functional organ in the embryo, and its blood vessels form a widespread conductive network within the organism. Blood vessels develop de novo, by the differentiation of endothelial progenitor cells (vasculogenesis) or by angiogenesis, which is the formation of new blood vessels from existing ones. This review presents an overview of the current knowledge on physiological and pathological angiogenesis in the horse including studies on equine endothelial cells. Principal study fields in equine angiogenesis research were identified: equine endothelial progenitor cells; equine endothelial cells and angiogenesis (heterogeneity, markers and assessment); endothelial regulatory molecules in equine angiogenesis; angiogenesis research in equine reproduction (ovary, uterus, placenta and conceptus, testis); angiogenesis research in pathological conditions (tumours, ocular pathologies, equine wound healing, musculoskeletal system and laminitis). The review also includes a table that summarizes in vitro studies on equine endothelial cells, either describing the isolation procedure or using previously isolated endothelial cells. A particular challenge of the review was that results published are fragmentary and sometimes even contradictory, raising more questions than they answer. In conclusion, angiogenesis is a major factor in several diseases frequently occurring in horses, but relatively few studies focus on angiogenesis in the horse. The challenge for the future is therefore to continue exploring new therapeutic angiogenesis strategies for horses to fill in the missing pieces of the puzzle.

Microfluidic Quantitative PCR Detection of 12 Transgenes from Horse Plasma for Gene Doping Control

Gene doping, an activity which abuses and misuses gene therapy, is a major concern in sports and horseracing industries. Effective methods capable of detecting and monitoring gene doping are urgently needed. Although several PCR-based methods that detect transgenes have been developed, many of them focus only on a single transgene. However, numerous genes associated with athletic ability may be potential gene-doping material. Here, we developed a detection method that targets multiple transgenes. We targeted 12 genes that may be associated with athletic performance and designed two TaqMan probe/primer sets for each one. A panel of 24 assays was prepared and detected via a microfluidic quantitative PCR (MFQPCR) system using integrated fluidic circuits (IFCs). The limit of detection of the panel was 6.25 copy/μL. Amplification-specificity was validated using several concentrations of reference materials and animal genomic DNA, leading to specific detection. In addition, target-specific detection was successfully achieved in a horse administered 20 mg of the EPO transgene via MFQPCR. Therefore, MFQPCR may be considered a suitable method for multiple-target detection in gene-doping control. To our knowledge, this is the first application of microfluidic qPCR (MFQPCR) for gene-doping control in horseracing.

Production and Application of Multicistronic Constructs for Various Human Disease Therapies

The development of multicistronic vectors has opened up new opportunities to address the fundamental issues of molecular and cellular biology related to the need for the simultaneous delivery and joint expression of several genes. To date, the examples of the successful use of multicistronic vectors have been described for the development of new methods of treatment of various human diseases, including cardiovascular, oncological, metabolic, autoimmune, and neurodegenerative disorders. The safety and effectiveness of the joint delivery of therapeutic genes in multicistronic vectors based on the internal ribosome entry site (IRES) and self-cleaving 2A peptides have been shown in both in vitro and in vivo experiments as well as in clinical trials. Co-expression of several genes in one vector has also been used to create animal models of various inherited diseases which are caused by mutations in several genes. Multicistronic vectors provide expression of all mutant genes, which allows the most complete mimicking disease pathogenesis. This review comprehensively discusses multicistronic vectors based on IRES nucleotide sequence and self-cleaving 2A peptides, including its features and possible application for the treatment and modeling of various human diseases.

Potential therapeutic application of mesenchymal stem cells in ophthalmology

At present a wide variety of methods have been proposed to treat eye disorders, drug therapies are most commonly used. It should be noted that effective treatment modalities especially for degeneration of the retina and optic nerve are lacking. In the last few years stem cell transplantation has been proposed as an alternative method. The opportunities that stem cells provide within clinical use are almost unlimited. These cells are presently applied to treat various traumatic and degenerative disorders due to their unique biologic properties. Stem cells have high proliferative capabilities and are a self-maintained population of cells capable of differentiating into different cell types. Thus, they are represent a very primary stage of a cell lineage. Their ability to differentiate into different pathways provides animals with great plasticity in the renewal of somatic cells in postnatal ontogenesis. Pre-clinical and clinical ophthalmology studies where mesenchymal stem cells are applied and various methods of their administration are discussed herein. In addition the safety and efficacy of using bone marrow- and adipose tissue-derived mesenchymal stem cells have been discussed.

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.