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    “They did not know it was impossible,
    so they did it”
    M. Twain

    Article year and first author
    Spaas et al., 2013

    Journal
    Vet J

    Volume and pages
    195; 107-113

    Manuscript
    Culture and characterisation of equine peripheral blood mesenchymal stromal cells

    Abstract

    Although the use of mesenchymal stromal cells (MSCs) for the treatment of orthopaedic injuries in horses has been reported, no official guidelines exist that classify a particular cell as an equine MSC. Given the limited characterisation of peripheral blood (PB)-derived equine MSCs in particular, this study aimed to provide more detailed information in relation to this cell type. Mesenchymal stromal cells were isolated from equine PB samples and colony forming unit (CFU) assays as well as population doubling times (PDTs) (from P0 to P10) were performed. Two types of colonies, ‘fingerprint’ and dispersed, could be observed based on macroscopic and microscopic features.

    Moreover, after an initial lag phase (as indicated by a negative PDT at P0 to P1) the MSCs divided rapidly as indicated by a positive PDT at all further passages. Immunophenotyping was carried out with trypsin- as well as with accutase-detached MSC to evaluate potential trypsin-sensitive epitope destruction on particular antigens. Isolated MSC were positive for CD29, CD44, CD90 and CD105, and negative for CD45, CD79a, MHC II and a monocyte/macrophage marker, irrespective of the cell detaching agent used. Trilineage differentiation of the MSCs towards osteoblasts, chondroblasts and adipocytes was confirmed using a range of histochemical stains.

    Article year and first author
    Broeckx et al., 2013

    Journal
    J Stem Cell Res Ther

    Volume and pages
    3; 147      

    Manuscript
    Guidelines to Optimize Survival and Migration Capacities of Equine Mesenchymal Stem Cells

    Abstract

    Background:
    Although mesenchymal stem cell (MSC) therapy is commonly being used in veterinary medicine, no specific guidelines are described to guarantee an optimal cell survival and migration. However, this is indispensable in order to assure an optimal clinical use.

    Methods:
    In the present study, equine peripheral blood (PB)-derived MSCs were isolated and characterized. In order to determine the optimal parameters for long-term cryopreservation, the effects of different dimethyl sulfoxide (DMSO) concentrations (5-20%) and thawing methods (temperature-controlled or hand-thawed) on MSC viability were evaluated by means of trypan blue staining. Afterwards, MSC storage was evaluated for 12 months using only 10% of DMSO as a cryoprotectant without rate-controlled freezing. Then, the influence of frequently used anaesthetics and injectable gels on MSC viability was assessed. Finally, the migration capacity of MSCs through hyaluronic acid at different concentrations was assessed.
    Results: Firstly, we demonstrated that the DMSO concentration and the thawing method had no considerable influence on MSC viability within the 4 hour evaluation after thawing. Secondly, anaesthetics were highly cytotoxic and only 10% of the MSCs survived 3 hours of their presence. Hyaluronic acid- and glycosaminoglycan-based gels were compatible with MSCs and allowed a high cell survival (more than 90%) within 48 hours of follow-up. However, in a polyacrylamide gel, approximately 80% of the MSCs died within 48 hours. Finally, the concentration of the gel influenced the migration capacity of the MSCs. Indeed, only 60% of the MSCs in 20 mg/ml of hyaluronic acid attached to the underlying surface within 48 hours, whereas almost 100% of the MSCs in 10 mg/ml of the same substance were able to migrate through the gel.

    Conclusion:
    The present study reports practical guidelines for the clinical application of equine PB-derived MSCs.


    Article year and first author
    Broeckx et al., 2012

    Journal
    J Tissue Sci Eng

    Volume and pages
    S11; 001      

    Manuscript
    Tenogenesis of Equine Peripheral Blood-Derived Mesenchymal Stem Cells: In vitro Versus In vivo

    Abstract

    Background:
    Tendon injuries are a major cause of orthopaedic injuries, and often compromise the return to the same performance level. Therefore, different regenerative therapies, such as Mesenchymal Stem Cells (MSCs) and Platelet-rich Plasma (PRP) have been explored to improve tendon healing in horses. However, ectopic bone formation of undifferentiated cells is a major concern, because of reports of this phenomenon, after intralesional injections of MSCs in rabbit Achilles tendons.

    Methods:
    After MSC and PRP isolation of the Peripheral Blood (PB) of a donor horse, tenogenic induction of the MSCs (Tendo-Cell®) was confirmed through morphological changes and immunohistochemistry stainings. Secondly, the safety and clinical effects (ultrasound imaging) of Tendo-Cell®, in combination with PRP, was evaluated after a single intralesional injection in the lateral edge of the Superficial Digital flexor tendon (SDFT) (n=10) and the lateral branch of the suspensory ligament (SL) (n=15) in 25 horses. Different independent veterinary practitioners were asked to give a score from 0-5, at approximately 6 weeks after treatment (0=no ultrasonic improvement and 5=no ultrasonic abnormalities, the tendon has the same consistency and fiber orientation as the contralateral tendon).

    Results:
    In 96% of the patients, the same positive evolution was noticed on the ultrasound images, and this was translated to a score 3 or more (≥ 60% improvement or better than a successful conservative therapy). In addition, for both tendons (SDFT & SL), 40% of the horses received a score 5.

    Conclusion:
    In conclusion, the present study is the first to describe the treatment of lesions in the SDFT and SL, with allogenic tenogenic induced PB-derived MSCs, in combination with PRP, with a positive outcome in 24 out of the 25 horses.

    Article year and first author
    Spaas et al., 2012

    Journal
    VDT

    Volume and pages
    81; 11-15      

    Manuscript
    Treatment of equine degenerative joint disease with autologous peripheral blood-derived mesenchymal stem cells: a case report

    Abstract

    A 5-year-old German Warmblood stallion with chronic lameness, attributable to degenerative joint disease (DJD) of the pastern joint unresponsive to medical treatments, was treated with autologous mesenchymal stem cells (MSC). These MSC were isolated from the peripheral blood (PB) of the patient and injected into the pastern joint, at a concentration of 2.5x106 cells, twice with an 8-week interval. The positive response to this stem cell treatment was documented by visual gait evaluation as well as objective pressure plate analyses. This paper is the first to describe the use of autologous PB-derived MSC to treat a horse suffering from chronic DJD. The favorable outcome of this single case may stimulate further research on the use of equine peripheral blood as a source of autologous MSC in equine regenerative medicine.

    Article year and first author
    Beerts et al., 2013

    Journal
    J Tissue Sci Eng

    Volume and pages
    4; 125   

    Manuscript
    Desmitis of the Accessory Ligament of the Equine Deep Digital Flexor Tendon: A Regenerative Approach

    Abstract

    Background:
    Desmitis of the accessory ligament of the deep digital flexor tendon (ALDDFT) is a very common problem in different breeds of sport horses, with an inability to heal adequately after conservative therapy in many cases. However, the treatment of different kinds of tendon lesions with platelet-rich plasma (PRP), mesenchymal stem cells (MSCs), or even tenogenic induced MSCs have been reported with promising results.

    Methods:
    After MSC and PRP isolation of the peripheral blood (PB) of a donor horse, tenogenic induction of the MSCs (Tendo-Cell®) was confirmed, and samples were microbiologically tested and frozen. Adverse and clinical effects (macroscopic noticeable swelling, lameness and ultrasound imaging) of PRP (n=4), or Tendo-Cell® (n=4) were evaluated after a single intralesional injection in the ALDDFT in 8 horses. For each case, two independent veterinary practitioners were asked to give a score from 0-5, at approximately 6 weeks and 4 months after treatment (0=no ultrasonographic improvement and 5=90-100% improvement, or (nearly) no ultrasonographic abnormalities, the ligament has (almost) no hypo-echoic foci, and (nearly) the same fiber orientation as the contralateral ligament).

    Results:
    At approximately 6 weeks post injection, the ultrasound images of all 4 horses treated with PRP only slightly improved. Therefore, a score 2/5 was given by the two attending veterinarians to all 4 patients. In the Tendo-Cell® treated group, on the other hand, all 4 horses received a score 4/5 by the same veterinarians at 6 weeks after intralesional injection. This implicates that the lesions improved about 80% on the ultrasound images, which was much better than the 40% improvement in the PRP treated group.

    Conclusion:
    This study reports a positive clinical and ultrasonographical outcome after tenogenic induced MSC (Tendo-Cell®) treatment of desmitis of the equine ALDDFT, whereas no considerable improvements could be noticed
    after treatment with allogenic PRP.


    Article year and first author
    Broeckx et al., 2013

    Journal
    J Stem Cell Res Ther

    Volume and pages
    3; 136      

    Manuscript
    The Influence of Allogenic Mesenchymal Stem Cells on the Hematological Status of Horses

    Abstract

    Background:
    It has been reported that mesenchymal stem cells (MSCs) have homing capacities after an intravenous injection and immunomodulating effects in vitro. However, there are no reports on their effect on the animal’s hematological status.

    Methods:
    Therefore, MSCs were isolated and characterized from a 4-years-old donor horse after having tested his blood on a wide range of transmittable diseases. Then, 6 horses (13- to 15-years-old) received a single injection into the jugular vein: 3 with MSCs and 3 with the carrier fluid consisting of DMEM and 10% of DMSO. Multiple blood samples were taken at different time points at the same time of the day: before the intravenous MSC (Veno-Cell®) injection (T0) and 1 day (T1), 1 week (T2), 3 weeks (T3) and 2 months (T4) after the treatment.

    Results:
    In the control group no considerable changes were noticed over time, whereas, in all the treated horses, the baseline adjusted cortisol levels (P=0.0490) and number of neutrophils (P=0.0042) were significantly higher and glucose levels significantly lower (P=0.033). At time point T1, baseline adjusted blood thrombocyte levels were significantly higher in the treated group as compared to the control group (P<0.0001). On the other hand, baseline adjusted basophils, eosinophils, lymphocytes and monocytes remained approximately the same in all the horses regardless the treatment. Additionally, the levels of total protein, albumin, alkaline phosphatase and all the tested minerals were not influenced by the injections.

    Conclusion:
    In all patients consistent alterations in hematological parameters were noticed after intravenous allogenic MSC treatment. However, further research is warranted in order to verify what the exact influence of these changes might be on the animal’s metabolism, general condition and performance ability.

    Article year and first author
    Broeckx et al., 2014

    Journal
    Curr Stem Cell Res Ther

    Volume and pages
    9; 452-457      

    Manuscript
    Intravenous Application of Allogenic Peripheral Blood-Derived Mesenchymal Stem Cells: A Safety Assessment in 291 Equine Recipients

    Abstract

    It has been reported that mesenchymal stem cells (MSCs) have homing capacities and immunomodulating effects after an intravenous injection. However, transplanting MSCs in murine tail veins can result in pulmonary reactions and even death of the animals. Unfortunately, only a few intravenous MSC transplantations have been reported in large animal species and these were performed in a limited number of individuals. To assess the safety of MSC transplantations, a large study on 291 recipient horses is reported here. MSCs were isolated from the peripheral blood (PB) of a 4-year-old and 6-year-old donor horse after having tested their PB for a wide range of transmittable diseases. The MSC samples from both donor horses were characterized and resuspended in 1ml of Dulbecco’s Modified Eagle Medium (DMEM) supplemented with 10% Dimethyl Sulfoxide (DMSO). After hand-thawing in the field, 291 horses with ages ranging from 3-months to 33-years were directly injected into their jugular vein. 281 horses (97%) received a single injection of a physiological dose of 0.2 x106 MSCs, 5 horses (1.7%) were re-injected after approximately 6 weeks (using the same dose and donor cells) and a single superphysiological dose of 106 MSCs was administered to 5 horses as well. In total, 176 recipients were injected with MSCs from the 4-year-old donor and 115 recipients received MSCs from the 6-year-old donor. From all the injected horses (n=291) no acute clinical adverse effects were noticed. Apart from one horse that died of colic 7 months after the treatment, no deaths were registered and all the horses were monitored for 1 year after the injection. In conclusion, no adverse effects were noticed in 291 recipients after an intravenous injection of allogenic PB-derived MSCs. Nevertheless, further research is warranted in order to verify the immunogenic properties of these cells after allogenic transplantation into various (patho)physiological sites.

    Article year and first author
    Broeckx et al., 2014

    Journal
    PLoS One      

    Volume and pages
    9; e85917     

    Manuscript
    Regenerative Therapies for Equine Degenerative Joint Disease: A Preliminary Study

    Abstract

    Degenerative joint disease (DJD) is a major cause of reduced athletic function and retirement in equine performers. For this reason, regenerative therapies for DJD have gained increasing interest. Platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) were isolated from a 6-year-old donor horse. MSCs were either used in their native state or after chondrogenic induction. In an initial study, 20 horses with naturally occurring DJD in the fetlock joint were divided in 4 groups and injected with the following: 1) PRP; 2) MSCs; 3) MSCs and PRP; or 4) chondrogenic induced MSCs and PRP. The horses were then evaluated by means of a clinical scoring system after 6 weeks (T1), 12 weeks (T2), 6 months (T3) and 12 months (T4) post injection. In a second study, 30 horses with the same medical background were randomly assigned to one of the two combination therapies and evaluated at T1. The protein expression profile of native MSCs was found to be negative for major histocompatibility (MHC) II and p63, low in MHC I and positive for Ki67, collagen type II (Col II) and Vimentin. Chondrogenic induction resulted in increased mRNA expression of aggrecan, Col II and cartilage oligomeric matrix protein (COMP) as well as in increased protein expression of p63 and glycosaminoglycan, but in decreased protein expression of Ki67. The combined use of PRP and MSCs significantly improved the functionality and sustainability of damaged joints from 6 weeks until 12 months after treatment, compared to PRP treatment alone. The highest short-term clinical evolution scores were obtained with chondrogenic induced MSCs and PRP. This study reports successful in vitro chondrogenic induction of equine MSCs. In vivo application of (induced) MSCs together with PRP in horses suffering from DJD in the fetlock joint resulted in a significant clinical improvement until 12 months after treatment.


    Article year and first author
    Broeckx et al., 2014

    Journal
    Curr Stem Cell Res Ther

    Volume and pages
    9; 497-503

    Manuscript
    Allogenic Mesenchymal Stem Cells as a Treatment for Equine Degenerative Joint Disease: A Pilot Study

    Abstract

    Cell-based therapies, such as treatments with mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) are thought to have beneficial effects on the clinical outcome of orthopedic injuries, but very few animal studies with large sample size are published so far. Therefore, the aim of this study was to assess the safety and report the clinical outcome of allogenic, immature or chondrogenic induced MSCs in combination with PRP for the treatment of degenerative joint disease (DJD) in 165 horses.

    MSCs and PRP were isolated from a 6-year-old donor horse and transplanted either in their native state or after chondrogenic induction in combination with PRP into degenerated stifle (n=30), fetlock (n=58), pastern (n=34) and coffin (n=43) joints. Safety was assessed by means of clinical evaluation and the outcome was defined as failure to return to work (score 0), rehabilitation (score 1), return to work (score 2) and return to previous level (score 3), shortly (6 weeks) after treatment or at 18 weeks for the patients that returned for long-term follow-up (n=91).

    No adverse effects were noticed, except for three patients who showed a moderate flare reaction within one week after treatment of the fetlock joint without long-term effects (1.8% of 165 horses). Already after 6 weeks, 45% (native MSCs) and 60% (chondrogenic induced MSCs) of the treated patients returned to work (=> score 2+3) and the beneficial effects of the treatment further increased after 18 weeks (78% for native MSCs and 86% for chondrogenic induced MSCs). With the odds ratio of 1.47 for short-term and 1.24 for long-term, higher average scores (but statistically not significant) could be noticed using chondrogenic induced MSCs as compared to native MSCs. For all three lower limb joints a higher percentage of the treated patients returned to work after chondrogenic induced MSC treatment, whereas the opposite trend could be noticed for stifle joints. Nevertheless, more protracted follow-up data should confirm the sustainability of these joints.

    Article year and first author
    Spaas et al., 2015

    Journal
    Cell Physiol Biochem

    Volume and pages
    37; 651-665

    Manuscript
    Chondrogenic Priming at Reduced Cell Density Enhances Cartilage Adhesion of Equine Allogeneic MSCs - a Loading Sensitive Phenomenon in an Organ Culture Study with 180 Explants

    Abstract

    Background:
    Clinical results of regenerative treatments for osteoarthritis are becoming increasingly significant. However, several questions remain unanswered concerning mesenchymal stem cell (MSC) adhesion and incorporation into cartilage. 

    Methods:
    To this end, peripheral blood (PB) MSCs were chondrogenically induced and/or stimulated with pulsed electromagnetic fields (PEMFs) for a brief period of time just sufficient to prime differentiation. In an organ culture study, PKH26 labelled MSCs were added at two different cell densities (0.5 x106 vs 1.0 x106). In total, 180 explants of six horses (30 per horse) were divided into five groups: no lesion (i), lesion alone (ii), lesion with naïve MSCs (iii), lesion with chondrogenically-induced MSCs (iv) and lesion with chondrogenically-induced and PEMF-stimulated MSCs (v). Half of the explants were mechanically loaded and compared with the unloaded equivalents. Within each circumstance, six explants were histologically evaluated at different time points (day 1, 5 and 14). 

    Results:
    COMP expression was selectively increased by chondrogenic induction (p = 0.0488). PEMF stimulation (1mT for 10 minutes) further augmented COL II expression over induced values (p = 0.0405). On the other hand, MSC markers remained constant over time after induction, indicating a largely predifferentiated state. In the unloaded group, MSCs adhered to the surface in 92.6% of the explants and penetrated into 40.7% of the lesions. On the other hand, physiological loading significantly reduced surface adherence (1.9%) and lesion filling (3.7%) in all the different conditions (p < 0.0001). Remarkably, homogenous cell distribution was characteristic for chondrogenic induced MSCs (+/- PEMFs), whereas clump formation occurred in 39% of uninduced MSC treated cartilage explants. Finally, unloaded explants seeded with a moderately low density of MSCs exhibited greater lesion filling (p = 0.0022) and surface adherence (p = 0.0161) than explants seeded with higher densities of MSCs. In all cases, the overall amount of lesion filling decreased from day 5 to 14 (p = 0.0156).

    Conclusion:
    The present study demonstrates that primed chondrogenic induction of MSCs at a lower cell density without loading results in significantly enhanced and homogenous MSC adhesion and incorporation into equine cartilage.

    Article year and first author
    Vandenberghe et al., 2015

    Journal
    Front Vet Sci

    Volume and pages
    2; 49

    Manuscript
    Tenogenically induced allogeneic mesenchymal stem cells for the treatment of proximal suspensory ligament desmitis in a horse

    Abstract

    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.

    Article year and first author
    Gomeiro et al., 2016

    Journal
    Vet Res Commun

    Volume and pages
    40; 39-48

    Manuscript
    Tenogenic induction of equine mesenchymal stem cells by means of growth factors and low-level laser technology

    Abstract

    Tendons regenerate poorly due to a dense extracellular matrix and low cellularity. Cellular therapies aim to improve tendon repair using mesenchymal stem cells and tenocytes; however, a current limitation is the low proliferative potential of tenocytes in cases of severe trauma. The purpose of this study was to develop a method useful in veterinary medicine to improve the differentiation of Peripheral Blood equine mesenchymal stem cells (PB-MSCs) into tenocytes. PB-MSCs were used to study the effects of the addition of some growth factors (GFs) as TGFβ3 (transforming growth factor), EGF2 (Epidermal growth factor), bFGF2 (Fibroblast growth factor) and IGF-1 (insulin-like growth factor) in presence or without Low Level Laser Technology (LLLT) on the mRNA expression levels of genes important in the tenogenic induction as Early Growth Response Protein-1 (EGR1), Tenascin (TNC) and Decorin (DCN). The singular addition of GFs did not show any influence on the mRNA expression of tenogenic genes whereas the specific combinations that arrested cell proliferation in favour of differentiation were the following: bFGF2 + TGFβ3 and bFGF2 + TGFβ3 + LLLT. Indeed, the supplement of bFGF2 and TGFβ3 significantly upregulated the expression of Early Growth Response Protein-1 and Decorin, while the use of LLLT induced a significant increase of Tenascin C levels. In conclusion, the present study might furnish significant suggestions for developing an efficient approach for tenocyte induction since the external administration of bFGF2 and TGFβ3, along with LLLT, influences the differentiation of PB-MSCs towards the tenogenic fate.

    Article year and first author
    Quattrocelli et al., 2016

    Journal
    Stem Cell reports

    Volume and pages
    6; 55-63

    Manuscript
    Equine-Induced Pluripotent Stem Cells Retain Lineage Commitment Toward Myogenic and Chondrogenic Fates

    Abstract

    Induced pluripotent stem cells (iPSCs) hold great potential not only for human but also for veterinary purposes. The equine industry must often deal with health issues concerning muscle and cartilage, where comprehensive regenerative strategies are still missing. In this regard, a still open question is whether equine iPSCs differentiate toward muscle and cartilage, and whether donor cell type influences their differentiation potential. We addressed these questions through an isogenic system of equine iPSCs obtained from myogenic mesoangioblasts (MAB-iPSCs) and chondrogenic mesenchymal stem cells (MSC-iPSCs). Despite similar levels of pluripotency characteristics, the myogenic differentiation appeared enhanced in MAB-iPSCs. Conversely, the chondrogenic differentiation was augmented in MSC-iPSCs through both teratoma and in vitro differentiation assays. Thus, our data suggest that equine iPSCs can differentiate toward the myogenic and chondrogenic lineages, and can present a skewed differentiation potential in favor of the source cell lineage.


    Article year and first author
    Beerts et al., 2017

    Journal
    Front Vet Sci

    Volume and pages
    4; 158

    Manuscript
    Tenogenically Induced Allogeneic Peripheral Blood Mesenchymal Stem Cells in Allogeneic Platelet-Rich Plasma: 2-Year Follow-up after Tendon or Ligament Treatment in Horses

    Abstract

    Poor healing of tendon and ligament lesions often results in early retirement of sport horses. Therefore, regenerative therapies are being explored as potentially promising treatment for these injuries. In this study, an intralesional injection was performed with allogeneic tenogenically induced mesenchymal stem cells and platelet-rich plasma 5–6 days after diagnosis of suspensory ligament (SL) (n = 68) or superficial digital flexor tendon (SDFT) (n = 36) lesion. Clinical, lameness and ultrasonographic evalu-ation was performed at 6 and 12 weeks. Moreover, a survey was performed 12 and 24 months after treatment to determine how many horses were competing at original level and how many were re-injured. At 6 weeks, 88.2% of SL (n = 68) and 97.3% of SDFT lesions (n = 36) demonstrated moderate ultrasonographic improvement. At 12 weeks, 93.1% of SL (n = 29) and 95.5% of SDFT lesions (n = 22) improved convincingly. Moreover, lameness was abolished in 78.6% of SL (n = 28) and 85.7% (n = 7) of SDFT horses at 12 weeks. After 12 months (n = 92), 11.8% of SL and 12.5% of SDFT horses were re-injured, whereas 83.8 of SL and 79.2% of SDFT returned to previous performance level. At 24 months (n = 89) after treatment, 82.4 (SL) and 85.7% (SDFT) of the horses returned to previous level of performance. A meta-analysis was performed on relevant published evidence evaluating re-injury 24 months after stem cell-based [17.6% of the SL and 14.3% of the SDFT group (n = 89)] versus conventional therapies. Cell therapies resulted in a significantly lower re-injury rate of 18% [95% confidence interval (CI), 0.11–0.25] 2 years after treatment compared to the 44% re-injury rate with conventional treatments (95% CI, 0.37–0.51) based on literature data (P < 0.0001).

    Article year and first author
    Broeckx et al., 2018

    Journal
    Res Vet Sci

    Volume and pages
    117; 246-254

    Manuscript
    Equine allogeneic chondrogenic induced mesenchymal stem cells: A GCP target animal safety and biodistribution study

    Abstract

    The safety of the intra-articular use of mesenchymal stem cells (MSCs) is scarcely reported. Therefore, the goal of this study was to investigate the safety of a single intra-articular injection with allogeneic chondrogenic induced MSCs combined with equine plasma (=the investigational product: IVP) compared to a saline (0.9% NaCl) placebo control (=control product: CP). Sixteen healthy experimental horses were randomly assigned to receive a single intra-articular injection with either the IVP (n =8) or the CP (n=8) in the left metacarpophalangeal joint. All horses underwent a daily clinical assessment throughout the entire study period of 42 days to assess adverse events. Additionally, a local joint assessment and a lameness examination were performed daily during the first two weeks, and weekly the following 4 weeks. Blood samples were taken weekly for hematological and biochemical analysis. At the end of the study period, horses of the IVP group were euthanized for a thorough necropsy and to check for biodistribution. Tissue samples of the injected joint were collected for histological examination. In both CP and IVP treated horses a mild transient subjective increase in periarticular temperature and lameness was noted after the intra-articular injection with no significant differences between the treatment groups. No distribution of the cells was found using immunohistochemistry and no ectopic tissue formation or signs of inflammation were found on histology. A single intra-articular injection of allogeneic chondrogenic induced MSCs combined with allogeneic plasma in horses had the same clinical side effects as an intra-articular injection with saline solution.