Veterinary Research Forum

Abstract Scaffolds play a crucial role in tendon healing by providing structural support, promoting cell infiltration, and guiding tissue regeneration. Polycaprolactone (PCL) has been used as a polymer in biological scaffolds for several tissue engineering studies. This study aimed to investigate the effects of curcumin-loaded PCL scaffold on Achilles tendon using a tenotomy model in rats. Twenty adult male Wistar rats were randomized into two groups. In control group, tenotomy and suture placement were performed. The identical intervention followed by the implantation of curcumin-loaded PCL scaffold around the tendon stumps was performed in the treatment group. The nanofibrous PCL scaffold containing 5.00% curcumin was fabricated by electrospinning. Walking track analysis was performed weekly. Then, after 6 weeks, histopathological examination and tendon mechanical tests were performed. The weekly walking track analysis revealed a significant improvement in Achilles functional index in scaffold-treated rats from week three to six. The rate of functional improvement was remarkably slower in the control group. Histopathological examination revealed aseptic inflammation and enhanced neovascularization in the treatment group. Also, collagen arrangement and density were significantly improved in this group compared to the control samples including less regular orientation and loose organization of collagen fibers. Significant increase in mechanical properties, except for strain, was observed in the treatment group. The present study demonstrated that implantation of curcumin-loaded PCL scaffold resulted in increased fibrillar architecture, as well as improved mechanical properties and Achilles functional index in rats. To reduce the biodegradation-induced inflammation, an anti-inflammatory treatment is recommended.

Abstract This study aimed to investigatenuchal ligament (NL) autograft on experimental tendon defect healing in donkeys. Eight healthy donkeys were used. The left forelimb’s superficial digital flexor (SDF) tendon was assigned as treatment, and the right forelimb was allocated as the control group (without surgical intervention). A 3×1.5 cm segment of the funicular part of the NL was excised. A full thickness defect created in the treatment tendon and was grafted with the excised NL. The following parameters were evaluated in 120 days postoperatively: clinical, ultrasonography, radiography, histopathology, biomechanical properties, and scanning and electronic transmission microscopy. There were no significant changes observed in the neck angle so that it was confirmed this treatment regimen preserved the head and neck situation without any considerable neck swelling. Weight-bearing in gait and trot was similar between both forelimbs at the end of the study. Mild to moderate adhesion was detected in the dorsal surface of the SDF tendon. There was no significant difference in the echogenicity and fiber alignment, respectively, on days 90 and 120 after surgery. Treatment significantly amplified the collagen diameter and enhanced the collagen fibril diameter and density considerably compared to the NL. The transplanted tissue was mostly in the remodeling or maturation phase, on day 120 postoperatively. It seems thatthe NL is biocompatible, almost biodegradable, and effective in tendon healing without metaplasia or tissue rejection.

Abstract Chitosan bears numerous properties, such as biocompatibility, biodegradability and non-toxicity making it suitable for use in different biomedical fields. Zinc (Zn) is required for fibroblasts proliferation and collagen synthesis as essential elements of wound healing. Its nanoparticles are well known for their capability to enhance wound healing by cell adhesion and migration improvement through growth factors-mediated mechanisms. Poor blood supply and unique histological characteristics of tendon make its regeneration always slow. Also, adhesion formation between tendon and its surrounding tissues is another problem for neotendon to return to its normal structure and functional activities. In this study, a novel tubular scaffold of zinc oxide (ZnO) nanoparticles loaded chitosan has been fabricated for tendon repair. Experimental complete tenotomy of deep digital flexor tendon in a rabbit model was done and scaffolds were placed in the transected area after two ends suturing. After four and eight weeks, adhesion formation around the tendons and tissue reaction to the scaffolds were evaluated macroscopically. Inflammation, angiogenesis and collagen fibers arrangement were also analyzed in histopathological evaluations. After eight weeks, the scaffolds were absorbed completely, adhesions around the tendon were decreased and there was no sign of significant tissue reaction and/or infection in histopathological analyses. The reduced adhesion formation, improved gliding function and better histopathological characteristics suggest this scaffold application as a potential therapy in treatment of tendon acute injuries.

Abstract Tendon rupture in dogs is generally the result of a direct trauma. This report described the use of adjacent muscle autogenic fascial graft for reconstruction of distal rupture of long digital extensor tendon in a dog. A two-year-old male mix breed dog, was presented with a non-weight bearing lameness of the right hind limb and a deep rupture of lateral side of right tarsus. History taking revealed that this rupture appeared without any apparent cause, when walking around the farm, three days before. Radiography was done and no fracture was observed. Hyperextension of right tarsal joint compared to left limb was observed. Under general anesthesia, after dissections of the ruptured area, complete rupture of long digital extensor tendonwas revealed. Then, we attempted to locate the edge of the tendon, however, the tendon length was shortened approximately 1 cm. Hence, a strip of 1 cm length from fascia of cranial tibial muscle was harvested to fill the defect. The graft was sutured to the two ends of tendon using locking loop pattern. Subcutaneous layers and the skin were sutured routinely. Ehmer sling bandage was applied to prevent weight bearing on the surgical region. Re-examination and phone contact with the owner eight weeks and six months postoperatively revealed a poor lameness and excellent function of the dog, respectively. It could be concluded that the fascia of adjacent muscles can be used as an autogenic graft for reconstruction of some tendon ruptures.

Abstract Tendon never restores the complete biological and mechanical properties after healing. Several techniques are available for tissue-engineered biological augmentation for tendon healing like stem cells. Recently, synovium has been investigated as a source of cells for tissue engineering. In the present study, we investigated potentials of fibroblast like synoviocytes (FLSs) in tendon healing. Sixteen rabbits were divided randomly into control and treatment groups. One rabbit was used as a donor of synovial membrane (synovium). The injury model was unilateral complete transection through the middle one third of deep digital flexor tendon (DDFT). Subsequently, the tendon stumps were sutured with 3/0 nylon. In treatment group, 0.1 mL phosphate-buffered saline (PBS) solution containing 1 × 10⁶ nucleated cells of FLSs was injected intratendinously at both tendon stumps just next to incision line. In control group, 0.1 mL PBS without FLSs was used for intratendinous injection. Model animals were euthanized at eight weeks, DDFTs were harvested and prepared for biomechanical study. Results of study showed that, there was no significant differences in biomechanical parameters values between FLSs treated and control groups. In conclusion, intratendinous injection of FLSs did not improve biomechanical properties during eight weeks in rabbit.

Abstract Tendon never restores the complete biological and mechanical properties after healing. Bone marrow and recently adipose tissue have been used as the sources of mesenchymal stem cells, which have been proven to enhance tendon healing. Stromal vascular fraction (SVF), derived from adipose tissue by an enzymatic digestion, represents an alternative source of multipotent cells, which undergo differentiation into multiple lineages to be used in regenerative medicine. In the present study, we investigated potentials of this source on tendon healing. Twenty rabbits were divided into control and treatment groups. Five rabbits were used as donors of adipose tissue. The injury model was unilateral complete transection through the middle one third of deep digital flexor tendon. Immediately after suture repair, either fresh stromal vascular fraction from enzymatic digestion of adipose tissue or placebo was intratendinously injected into the suture site in treatments and controls, respectively. Cast immobilization was continued for two weeks after surgery. Animals were sacrificed at the third week and tendons underwent histological, immunohistochemical, and mechanical evaluations. By histology, improved fibrillar organization and remodeling of neotendon were observed in treatment group. Immunohistochemistry revealed an insignificant increase in collagen type III and I expression in treatments over controls. Mechanical testing showed significant increase in maximum load and energy absorption in SVF treated tendons. The present study showed that intratendinous injection of uncultured adipose derived stromal vascular fraction improved structural and mechanical properties of repaired tendon and it could be an effective modality for treating tendon laceration.