MSCT has been investigated and used clinically in dogs to treat OA,20-30 ligament injuries (eg, partial cranial cruciate ligament tears),31-36 and tendinopathies (eg, supraspinatus tendinopathy).37
Chondrocytes are easily damaged and heal poorly due to their low mitotic ability and due to their lack of blood and lack of lymphatic and nerve supply,38 making them an ideal therapeutic target for MSCT in dogs and humans.5 Several studies have investigated the use of AD MSCs for the treatment of naturally occurring OA affecting the canine hip, elbow, and shoulder joint.20-30 Most of these studies were well-designed, placebo-controlled, blinded, and randomized; many demonstrated reduction in pain on manipulation and range of motion20,21 and improvement in owner satisfaction20,21,25 and in subjective grading scale and objective lameness measurements.24,27,29 It is unclear whether the beneficial effects seen in these studies were due to the anti-inflammatory effects of MSCs, the repair or regeneration of articular cartilage, or a combination of these mechanisms.33,34
The investigation of MSCT in the treatment of other small animal orthopedic conditions (eg, cranial cruciate ligament tears) has been fueled by in vivo studies that have shown the potential for MSCs to engraft into the cranial cruciate ligament, meniscus, and cartilage.32,35,36 Although data are sparse, there is some clinical evidence suggesting that MSCs may be able to augment healing of early partial tears prior to development of mechanical instability, offering a potential nonsurgical solution.31
Use of culture-expanded BM MSCs in the treatment of tendon injuries has been investigated in experimental studies of horses and laboratory animals; MSCs were implanted in surgically or collagenase-induced tendon lesions and had positive effects on tissue organization, composition, and mechanics of these structures.37-40 In a veterinary clinical study, a combination of AD MSCs and platelet-rich plasma was used to treat supraspinatus tendinopathy in 55 dogs, 61.8% of which failed to respond to NSAIDs and 45.5% of which failed to respond to rehabilitation therapy.41 Improvements in objective gait analysis, lameness, and diagnostic ultrasonography results (ie, improved fiber pattern and tendon size) showed that AD MSCs combined with platelet-rich plasma may show promise in the treatment of this condition in dogs.41 Additional studies are needed to better evaluate MSCT in the treatment of this and other tendon injuries in dogs.