Fig. 3

Representative images of the radiology, ultrasonography and magnetic resonance imaging (MRI) assessments, taken from one animal from each group (control, MSC-naïve and MSC-primed). a Radiologic images (frontal views) are presented for two (score 3) and six months (score 3–4) of progression. Score 6 is the highest possible. Joint space narrowing and marginal bone remodeling (white arrows) were progressively observed; note that the radiologic evolution was similar between the three groups. b Ultrasound images are presented for Week 2 (first injection) and Week 3. Note that synovial effusion (dashed line) was faster reduced in both MSC-naïve and MSC-primed groups than in control. c Magnetic resonance images (T2* gradient echo [GE], sagittal planes) are presented for showing the different synovial effusion (black arrows) found between groups at two months (scores 1, 0 and 3 were assigned to the images showed for control, MSC-naïve and MSC-primed groups, respectively)