Flexor tendon injuries in zone II of the hand (i.e. between the distal volar crease and the distal interphalangeal joint) can be costly for both the afflicted individual and society because of the high cost of a long rehabilitation period, complicated by tendon ruptures or scarring with adhesion formation, causing impaired range of motion. The aim of the present thesis was to characterize more fully the deep flexor tendon, the tendon sheath and their response to injury in a rabbit model in order to find potential targets to improve the outcome of repair. The intrasynovial rabbit deep flexor tendon differed from the extrasynovial peroneus tendon in the expression of collagens and transforming growth factor-β1 gene expression. Differences were also found in collagen III and proteoglycans between regions of the flexor tendon subjected to either compressive or tensile load. After laceration and subsequent repair of the flexor tendon, a shift in collagen gene expression from type I to type III occurred. Proteoglycans were generally increased with the notable exception of decorin, a potential inhibitor of the profibrotic transforming growth factor-β1 which was markedly increased during the first two weeks after repair in tendon tissue but remained unaltered in the sheaths. Both vascular endothelial growth factor and basic fibroblast growth factor mRNA levels remained essentially unaltered, whereas insulin-like growth factor-1 increased later in the healing process, suggesting potential beneficial effects of exogenous addition, increasing tendon strength through stimulating tenocyte proliferation and collagen synthesis. Matrix metalloproteinase-13 mRNA levels increased and remained high in both tendon and sheath, whereas there was only a transient increase of matrix metalloproteinase-3 mRNA in tendon. We could also demonstrate a significant increase of the proportion of myofibroblasts, mast cells and neuropeptide containing nerve fibers in the healing tendon tissue, all components of the profibrotic myofibroblast-mast cell-neuropeptide pathway. / Biomolecular aspects of flexor tendon healing

Orientador: Edson Rosa Pimentel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T20:40:15Z (GMT). No. of bitstreams: 1 Almeida_MarcosdosSantosde_M.pdf: 1553509 bytes, checksum: 83b5ab6bad050eff3b5f36b0524643b3 (MD5) Previous issue date: 2011 / Resumo: A eletroacupuntura (EA) tem sido utilizada amplamente para o tratamento de uma variedade de doenças inflamatórias e para o alivio da dor. No entanto, não há relatos na literatura sobre o efeito da EA na composição e organização da matriz extracelular (MEC) de tendões em processo de cicatrização. Objetivo: Investigar através de análises bioquímicas e morfológicas, o efeito da EA durante o pico de síntese dos componentes da MEC, 15 dias após transecção parcial do tendão calcâneo de ratos. Materiais e Métodos: Ratos Wistar machos com 60 dias de idade foram divididos em 3 grupos: Não tenotomizados (G1), tenotomizados (G2) e tenotomizados e submetidos a EA (G3). Agulhas de acupuntura (AC) foram inseridas nos pontos E-36 e B-57 e uma corrente elétrica com onda farádica bipolar assimétrica na freqüência de 2 Hz e intensidade de 2-4 Volts foi aplicada nas agulhas por 20 minutos, 3 vezes por semana em dias alternados, em um total de 6 sessões. Análises bioquímicas foram feitas através da SDS-PAGE, dosagem de proteínas não colagênicas (PNCs), glicosaminoglicanos (GAGs) e hidroxiprolina. Análise da metaloproteinase-2 (MMP-2) foi realizada por zimografia. Para análise morfológica em microscopia de luz comum, os cortes foram corados com hematoxilina-eosina (HE) e azul de toluidina (AT). Para análise em microscopia de polarização os cortes foram corados com Ponceau SS e a birrefringência foi avaliada em termos de valor de média de cinza em pixels utilizando um analisador de imagem. Resultados: EA nos pontos utilizados não alterou a concentração de PNCs, GAGs ou a atividade enzimática da MMP-2 nos tendões transeccionados. Já a concentração de hidroxiprolina foi significativamente aumentada nestes tendões quando tratados com EA. Na análise morfológica nos cortes corados com HE e AT, aparentemente não houve alterações na composição nem na organização da MEC. No entanto, na análise da birrefringência houve uma maior reorganização das fibras de colágeno no grupo tratado com EA. Conclusão: Nossos resultados indicam que a EA pode oferecer benefícios terapêuticos para o tratamento de lesões tendíneas através do aumento do conteúdo do colágeno e da reorganização molecular de suas fibras / Abstract: Electroacupuncture (EA) has been used to treat a variety of inflammatory diseases and pain relief. Therefore, there are no reports in the literature about the effect of EA on the composition and organization of the extracellular matrix (ECM) of tendons in the healing process. Objective: To investigate by morphological and biochemical analysis, the effect of EA during the peak of synthesis of ECM components, 15 days after partial transection of the Achilles tendon of rats. Methods: Male Wistar rats with 60 days old were divided into three groups: no tenotomized (G1), tenotomized (G2) and tenotomized and submitted to EA (G3). Acupuncture (AC) needles were inserted in the E-36 and B-57 points and an electrical current with asymmetrical bipolar faradic wave at frequency of 2 Hz and intensity of 2-4 Volts was applied to the needles for 20 minutes, 3 times per week on alternate days, for a total of 6 sessions. Biochemical analyses were done by SDS-PAGE, dosage of non collagenous proteins (NCPs), glycosaminoglycans (GAGs) and hydroxyproline. Analysis of metalloproteinase-2 (MMP-2) was carried out by zymography. For morphological analyses, the sections were stained with hematoxilin-eosin (HE) and toluidine blue. For polarization microscopy analysis the sections were stained with Ponceau SS and birefringence was evaluated in terms of gray average values in pixels using an image analyzer. Results: EA at points used did not alter the concentration of NCPs, GAGs or the enzymatic activity of MMP-2 in transected tendons. However, the concentration of hydroxyproline was significantly increased when these tendons were treated with EA. In the morphological analysis, apparently there were no changes in the composition and organization of the ECM. However, analysis of the birefringence showed higher reorganization of collagen fibers in the group treated with EA. Conclusion: Our results indicate that EA may offer therapeutic benefits for treatment of tendon injuries by increasing the content of collagen and the molecular reorganization of its fibers / Mestrado / Anatomia / Mestre em Biologia Celular e Estrutural

Tendon injuries are prevalent, debilitating and difficult to treat. Common interventions such as anti-inflammatory medication, growth factor injections and surgery are associated with short-term efficacy and long rehabilitation periods. Tendons possess an incomplete healing response which is reparative (scar-mediated) rather than regenerative, resulting in a 'healed' tissue that is mechanically inferior to the native tendon. While it is widely accepted that mechanical-loading based treatments offer long-term symptomatic resolution and improved functionality, the exact mechanisms of action of such mechanotransduction-based healing cascades remain unclear. Nevertheless, there is significant motivation for the development of non-invasive and efficient rehabilitative treatments that mechanically stimulate the injured tendons to achieve functional healing responses. Focused Ultrasound (FUS) methods are an attractive treatment option as they are non-invasive, utilize higher intensities for shorter durations and are targeted to a very specific treatment volume, hence inducing significant bio-effects in the tissue without affecting surrounding structures. Herein, we present a body of work that includes the development of FUS pulsing to precisely target murine Achilles tendons and emphasize distinct bioeffects (thermal-dominant and mechanical-dominant). We investigated the feasibility of applying FUS pulsing to murine Achilles tendons ex vivo and in vivo and demonstrated that FUS can be safely applied without any deleterious effects in the tendons and surrounding tissues. The animals showed no symptoms of distress after multi-session treatments. Overall, results suggest that tendon material properties are not adversely altered by FUS pulsing. Histological analyses showed mild matrix disorganization, suggesting the need for slight modifications in the ultrasound pulsing parameters and treatment durations. When applied to injured tendons, mechanical dominant schemes seemed to drive larger improvements in material properties compared to thermal-dominant pulsing, confirming our original hypothesis that mechanical stimulation may play a bigger role in tendon healing compared to purely thermal-dominant stimulation. Additionally, feasibility of histotripsy ablation in murine Achilles tendons was successfully investigated ex vivo and in vivo and experimentation to further optimize these methods are ongoing. Such (non-thermal) ablative paradigms will be extremely useful when conservative treatment options are unavailable and debridement of scar tissue is warranted to interrupt the degenerative process and stimulate healing. Finally, a pilot investigation into FUS-induced strains was performed to guide our parameter selection process and deliver controlled strains to achieve healing responses (similar to current clinical rehabilitation protocols). We were able confirm that strains between 1% and 6% (or higher) can be induced by manipulating ultrasound treatment parameters. Overall, or results reiterate the potential of FUS in eliciting the desired bioeffects and thus achieve healing in tendons and provide a snapshot of the expected effects of using such pulsing methods to treat tendon injuries. / Doctor of Philosophy / Tendons are tissues that connect muscles to bones, and are unfortunately prone to injuries. Such injuries are prevalent and difficult to treat. Effective treatment options remain limited, as common methods such as surgery, anti-inflammatory medications and corticosteroid injections do not provide long-term relief. One of the few treatments that has been proven to provide symptomatic relief and improved the functionality of chronically (over a long period of time) injured tendons is physical therapy. However, researchers are still investigating the reasons for this successful healing response. Some limitations of physical therapy are long rehabilitation and recovery periods, and the need for patient compliance (i.e., performing painful exercises while already being under significant pain). In this research, we explore the use of a non-invasive modality known as ultrasound to treat tendon injuries. Ultrasound is commonly thought of as a diagnostic tool, i.e., to detect injuries in musculoskeletal medicine. It, however, is also an attractive therapeutic (treatment) modality, as sound waves can be concentrated in the required area of interest which results in different types of effects in the chosen tissue, such as heating. A huge advantage is that ultrasound is non-invasive, painless, and safe, as the energy is only applied to the chosen volume of interest and surrounding structures are unaffected. To examine the utility of therapeutic ultrasound in treating tendon injuries, we used a mouse model that has been previously used in our lab, and designed different types of ultrasound treatments that elicit two main types of effects in the tissue, namely, thermal, or heating effects and mechanical, or physical therapy-like effects. Prior to applying these treatments, we measured how much heating is produced in mouse Achilles tendons via these treatments, to establish safety. Once we identified safe thermal and mechanical treatment sets, we treated mouse Achilles tendons ex vivo, i.e., after euthanasia. We tested the mechanical properties of the treated tendons and determined that treatments do not alter the mechanical properties of tendons, which is encouraging, given that we do not want treatments to interfere with the properties of native tendons. We also examined the influence of treatments on structure of Achilles tendons after treatments and deducted that the structure was not damaged due to treatments. We followed up these studies with treatments conducted in live mice, which received four treatment sessions in one week. These studies were conducted to further determine the safety and tolerance to these procedures and also examine the healing effects of treatments in injured Achilles tendons. Results suggest that focused ultrasound treatments are safe and tolerable to mice and seem to elicit improvements in tendon properties. In other studies, we also examined a different ultrasound method named histotripsy, as a non-invasive alternative to dry needling (which is another methodology used to treat tendon injuries) and scar debridement (removal of scar tissue to stimulate a new healing response). This research establishes that therapeutic ultrasound is a novel, non-invasive alternative with good potential to treat tendon injuries. Future studies will investigate the effects of ultrasound treatments over longer durations and also aim to clarify the exact type and magnitude of physical therapy-like forces that are produced by ultrasound treatments. This understanding will enhance our treatment design process to be able to mimic clinical treatments that are known to be effective.

No description available.

No description available.

Extracellular matrix (ECM) is responsible for tendon strength and elasticity. Healed tendon ECM lacks structural integrity, leading to reinjury. Porcine urinary bladder matrix (UBM) provides a scaffold and source of bioactive proteins to improve tissue healing, but has received limited attention for treating tendon injuries. The objective of this study was to evaluate the ability of UBM to induce matrix organization and tenogenesis using a novel in vitro model. We hypothesized that addition of UBM to tendon ECM hydrogels would improve matrix organization and cell differentiation. Hydrogels seeded with bone marrow cells (n = 6 adult horses) were cast using rat tail tendon ECM ± UBM, fixed under static tension and harvested at 7 and 21 days for construct contraction, cell viability, histology, biochemistry, and gene expression. By day 7, UBM constructs contracted significantly from baseline, whereas control constructs did not. Both control and UBM constructs contracted significantly by day 21. In both groups, cells remained viable over time and changed from round and randomly oriented to elongated along lines of tension with visible compaction of the ECM. There were no differences over time or between treatments for nuclear aspect ratio, DNA, or glycosaminoglycan content. Decorin, matrix metalloproteinase 13, and scleraxis expression increased significantly over time, but not in response to UBM treatment. Mohawk expression was constant over time. Cartilage oligomeric matrix protein expression decreased over time in both groups. Using a novel ECM hydrogel model, substantial matrix organization and cell differentiation occurred; however, the addition of UBM failed to induce greater matrix organization than tendon ECM alone. / Master of Science / Tendon injuries are common in horses and are painful and can be career- and life-ending. Tendons have a special structure and organization that enables them to withstand high tensile forces without permanent deformation. Injured tendons heal by forming stiff, disorganized scar tissue that makes the tendon more prone to re-injury. The lining of urinary bladders from pigs (UBM) provides a physical mesh and signaling factors that help heal injuries in a variety of tissues to a more normal state. However, UBM has not been evaluated in a laboratory model of tendon tissue formation to determine how it can help heal tendon injuries. Three-dimensional models of new tendon tissue formation (neotendons) were made with rat tail tendon matrix and stem cells collected from horse bone marrow. The neotendons were placed under steady tension for 3 weeks. The models were collected after 1 and 3 weeks to measure their width, numbers of live cells, cell and matrix organization, levels of tendon matrix components and expression of genes found in tendons. Most cells in the neotendons remained alive during the study period. Over time, UBM-treated and untreated neotendons became narrower compared to their starting width. The width of UBM-treated neotendons decreased faster than non-treated neontendons in the first week of the study. Cells became longer, narrower, and oriented along lines of tension. Expression of genes important in tendon development and structure either increased or was constant over time. UBM treatment did not change cell shape or increase levels of tendon-associated genes, DNA, or tendon matrix components. Our novel tendon model successfully created organized tendon-like tissue when placed under tension. However, UBM treatment did not improve formation of tendon-like tissue to a greater extent than controls.

Orientador: Edson Rosa Pimentel / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T05:39:03Z (GMT). No. of bitstreams: 1 Aro_AndreaAparecidade_D.pdf: 5514361 bytes, checksum: 938312e7fcf5c6bdd9bba11064c61b15 (MD5) Previous issue date: 2012 / Resumo: A utilização de extratos vegetais com atividades farmacológicas pode ser promissora no tratamento de lesões tendíneas, considerando a presença de princípios ativos que estimulam a síntese de componentes da matriz extracelular (MEC). Portanto, o presente estudo teve como objetivo investigar após 7, 14 e 21 dias da lesão, os efeitos da aplicação tópica dos extratos de A. vera e A. chica sobre tendões parcialmente transeccionados de ratos. Os grupos tratados com o extrato da A. chica foram denominados A7, A14 e A21 (controles S7, S14 e S21), e após tratamento com a A. vera foram denominados Av7, Av14 e Av21 (controles B7, B14 e B21). Foram realizadas análises bioquímicas tais como Western blotting, zimografia e dosagens de hidroxiprolina, de proteínas não colagênicas (PNCs) e de glicosaminoglicanos (GAGs); assim como análises estruturais, ultraestruturais e funcionais. Após aplicação do extrato da A. chica, a concentração de PNCs foi menor em A7 e a de hidroxiprolina foi maior em A7 e A21, em relação aos controles. Considerando a MMP-9, menor quantidade foi detectada no grupo A14 comparado ao grupo S14. As isoformas latente, intermediária e ativa da MMP-2 foram observadas em todos os grupos, porém maiores quantidades das isoformas latente e intermediária foram encontradas em A21. Os resultados de Western blotting mostraram menor quantidade de colágenos tipos I e III em A7 comparado ao controle. Maior quantidade de dermatan sulfato (DS) foi detectada em A14, e quantidade inferior de DS e condroitin sulfato (CS) foi observada em A21 comparada ao S21. As medidas de birrefringência detectaram maior organização das fibras de colágeno no grupo A21 em relação ao controle, e as análises ultraestruturais mostraram muitos fragmentos de colágeno na região transeccionada nos grupos S7 e A7. A análise do CatWalk mostrou que os animais tratados com A. chica, exibiram maior pressão de contato das patas durante a marcha no 7° dia. Considerando a aplicação de A. vera, foi observada em SDS-PAGE banda menos intensa referente ao colágeno em Av14, confirmado por Western blotting. O grupo Av21 apresentou maior concentração de PNCs comparado ao seu controle. Na dosagem de hidroxiprolina, os grupos Av7 e Av14 apresentaram maiores concentrações, ao passo que Av21 apresentou valor inferior ao controle. O grupo Av14 apresentou maior concentração de GAGs sulfatados e menor quantidade de DS em relação ao controle. Menor quantidade de MMP-9 foi encontrada em Av14, e menores quantidades das isoformas latente e intermediária da MMP-2 foram observadas em Av7 e Av14 em relação aos controles. Maior quantidade da isoforma ativa da MMP-2 foi observada em Av21 comparado a B21. As medidas de birrefringência detectaram maior organização das fibras de colágeno em Av14 em relação ao controle. Ao passo que as medidas de dicroísmo linear realizadas nos cortes corados com azul de toluidina, mostraram menor organização dos GAGs em Av14 comparado ao controle. Nossa conclusão é que a aplicação tópica dos extratos da A. chica e da A. vera é efetiva na síntese e organização de componentes da MEC durante o processo de reparo / Abstract: The use of plant extracts bearing pharmacological activities may be promising in the treatment of tendon injuries, considering the presence of active principles that stimulate the synthesis of extracellular matrix components (ECM). Therefore, this study aimed to investigate after 7, 14 and 21 days of injury, the effects of topical application of extracts of A. vera and A. chica on the healing of partially transected tendons of rats. The groups treated with the extract of A. chica were called A7, A14 and A21 (controls S7, S14 and S21), and after treatment with A. vera were called Av7, Av14 and Av21 (controls B7, B14 and B21). Biochemical analysis were performed such as Western blotting, zymography and quantification of hydroxyproline, non-collagenous proteins (NCPs) and glycosaminoglycans (GAGs); as well as structural, ultrastructural and functional analysis. After application of the extract of A. chica, the concentration of non-collagenous proteins (NCPs) was lower in A7 and hydroxyproline was higher in A7 and A21, compared to controls. Considering the MMP-9, lower amount was found in A14 compared to S14. The latent, intermediate and active isoforms of MMP-2 were observed in all groups, but larger quantities of latent and intermediate isoforms were found in A21. The results of Western blotting showed a lower amount of collagen types I and III compared to the control A7. Higher amount of dermatan sulphate (DS) was detected in A14 and lower amounts of DS and chondroitin sulfate (CS) were observed in A21 compared to S21. The birefringence measurements showed a higher organization of collagen fibers in the A21 group compared to control, and ultrastructural analysis showed many fragments of collagen in the transected region of groups S7 and A7. Analysis of the Catwalk showed that animals treated with A. chica exhibited a higher contact pressure of the legs during walking on the 7th day. Considering the application of A. vera, less intense band related to collagen was observed on SDS-PAGE in Av14, confirmed by Western blotting. The group Av21had a higher concentration of NCPs compared to the control. In the dosage of hydroxyproline, Av7 and Av14 groups had higher concentrations in relation to their controls, while Av21 showed lower value than control group. The group Av14 had a higher concentration of glycosaminoglycans and lower amount of DS compared to control. Lower amount of MMP-9 was found in Av14, and lower amounts of intermediate and latent isoforms of MMP-2 were observed in Av7 and Av14 compared to controls. A higher amount of the active isoform of MMP-2 was observed in Av21 compared to B21. The birefringence measurements showed a higher organization of collagen fibers in Av14 compared to control. While linear dichroism measurements performed on sections stained with toluidine blue, showed lower organization of glycosaminoglycans in Av14 compared to control. Our conclusion is that the topical application of extracts of A. chica and A. vera is effective in the synthesis and organization of ECM components during the repair process / Doutorado / Biologia Celular / Doutor em Biologia Celular e Estrutural

Les tendinites sont des lésions communes chez le cheval athlète, ayant un impact financier et sportif considérable. Les cellules souches mésenchymateuses (CSMs) de moelle osseuse (MO) sont empiriquement utilisées en clinique pour améliorer la guérison des affections myoarthrosquelettiques. Cependant, il est nécessaire de standardiser les protocoles d’isolement des CSMs équines et d’analyser leurs effets sur la guérison tendineuse pour ajuster leur dose. Les objectifs de cette étude étaient de comparer 3 méthodes d’isolement des CSMs équines et d’établir un modèle de guérison tendineuse minimal invasif pour analyser l’effet des CSMs sur cette guérison. Des CSMs de MO du sternum de juments étaient isolées par 3 protocoles couramment utilisés (adhérence au pétri (Classique) et 2 méthodes par gradient de densité (Percoll et Ficoll)). La viabilité des cellules après isolement, le rendement d’isolement, le nombre de CSMs obtenues après 14 jours de culture et leurs caractéristiques fonctionnelles (renouvellement et différentiation) étaient comparés entre les 3 protocoles. Les résultats suggéraient que le Percoll était le meilleur protocole en termes de rendement et de capacité de renouvellement des cellules. La différence n’était pas significative pour leur viabilité et leur capacité de différentiation. Un modèle de guérison tendineuse, consistant en une ténectomie du tendon extenseur latéral du doigt fut ensuite développé. Cependant, la grande variabilité interindividuelle de qualité de guérison dans le groupe pilote implique une ré-évaluation du modèle. Des études futures, avec des CSMs isolées par le Percoll dans de nouveaux modèles de guérison tendineuse devraient permettre de déterminer la dose adéquate de CSMs. / In equine athletes, tendinitis lesions are common and lead to substantial financial losses. Bone marrow (BM) mesenchymal stem cells (MSCs) are employed clinically empirically to enhance healing of musculoskeletal injuries. However, there is a need to standardize equine MSC isolation protocols, to analyze the effects of MSCs on tendon healing and to optimize dosage. The objectives of the study were to compare 3 methods of equine MSC isolation and develop a minimally invasive model of tendon healing to analyze the effects of MSCs on tendon healing. BM MSCs from the sternum of mares were isolated by 3 protocols (adherence to a plastic culture dish (Classic) and two gradient density separation protocols (Percoll and Ficoll)) to compare for cell viability, MSC yield, number of MSCs attained after 14 days of culture and functional characteristics (self-renewal and multilineage differentiation) of the MSCs. The results suggested that the Percoll protocol was the best of those assessed in terms of MSC yield and self-renewal potential and that MSCs retrieved with the Ficoll protocol had the lowest self-renewal. There were no significant differences in terms of cell viability and differentiation capacity. A tendon healing model was then developed and consisted of a 0.5 cm tenectomy of the lateral digital extensor tendon. However, interanimal variation of healing quality was so high within the pilot group that the model should be re-evaluated. Further studies using MSCs isolated with Percoll in other novel models of tendon healing would allow determination of the adequate dosage of MSCs.

Les tendinites sont des lésions communes chez le cheval athlète, ayant un impact financier et sportif considérable. Les cellules souches mésenchymateuses (CSMs) de moelle osseuse (MO) sont empiriquement utilisées en clinique pour améliorer la guérison des affections myoarthrosquelettiques. Cependant, il est nécessaire de standardiser les protocoles d’isolement des CSMs équines et d’analyser leurs effets sur la guérison tendineuse pour ajuster leur dose. Les objectifs de cette étude étaient de comparer 3 méthodes d’isolement des CSMs équines et d’établir un modèle de guérison tendineuse minimal invasif pour analyser l’effet des CSMs sur cette guérison. Des CSMs de MO du sternum de juments étaient isolées par 3 protocoles couramment utilisés (adhérence au pétri (Classique) et 2 méthodes par gradient de densité (Percoll et Ficoll)). La viabilité des cellules après isolement, le rendement d’isolement, le nombre de CSMs obtenues après 14 jours de culture et leurs caractéristiques fonctionnelles (renouvellement et différentiation) étaient comparés entre les 3 protocoles. Les résultats suggéraient que le Percoll était le meilleur protocole en termes de rendement et de capacité de renouvellement des cellules. La différence n’était pas significative pour leur viabilité et leur capacité de différentiation. Un modèle de guérison tendineuse, consistant en une ténectomie du tendon extenseur latéral du doigt fut ensuite développé. Cependant, la grande variabilité interindividuelle de qualité de guérison dans le groupe pilote implique une ré-évaluation du modèle. Des études futures, avec des CSMs isolées par le Percoll dans de nouveaux modèles de guérison tendineuse devraient permettre de déterminer la dose adéquate de CSMs. / In equine athletes, tendinitis lesions are common and lead to substantial financial losses. Bone marrow (BM) mesenchymal stem cells (MSCs) are employed clinically empirically to enhance healing of musculoskeletal injuries. However, there is a need to standardize equine MSC isolation protocols, to analyze the effects of MSCs on tendon healing and to optimize dosage. The objectives of the study were to compare 3 methods of equine MSC isolation and develop a minimally invasive model of tendon healing to analyze the effects of MSCs on tendon healing. BM MSCs from the sternum of mares were isolated by 3 protocols (adherence to a plastic culture dish (Classic) and two gradient density separation protocols (Percoll and Ficoll)) to compare for cell viability, MSC yield, number of MSCs attained after 14 days of culture and functional characteristics (self-renewal and multilineage differentiation) of the MSCs. The results suggested that the Percoll protocol was the best of those assessed in terms of MSC yield and self-renewal potential and that MSCs retrieved with the Ficoll protocol had the lowest self-renewal. There were no significant differences in terms of cell viability and differentiation capacity. A tendon healing model was then developed and consisted of a 0.5 cm tenectomy of the lateral digital extensor tendon. However, interanimal variation of healing quality was so high within the pilot group that the model should be re-evaluated. Further studies using MSCs isolated with Percoll in other novel models of tendon healing would allow determination of the adequate dosage of MSCs.