The prospective randomized study is carried out at orthopaedic and traumatology, haematology and radiology departments. 50 patients were included in the study. Of the 25 patients in both groups, Group I (received the concentrate of marrow MSCs into the tendon- bone contact point at the site of the suture during surgery ) consisted of 7 women and 18 men ( mean age 51,2 years ), Group II ( without the use of MSCs ) consisted of 15 women and 10 men ( mean age 50,5 years ). Selection of patients into both groups was performed using permutation block randomization computer software Random Number Generator Software 7.0. All of radiographs/MRI/CT results were evaluated by an experienced radiologist specialized in musculoskeletal pathologies, that was blinded to the both groups of patients. Before entering the study, patients signed an informed consent created by the Ethical Committee of local hospital and were randomly assigned to one of the treatment possibilities with use of the Random Number Generator Software 7.0 by the method 1:1.

Before the surgical treatment, patients completed a questionnaire with VAS score, ASES score ( American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form ) and the Constant score. Further clinical control with completing these questionnaires is 6 months after surgery, 1 year after surgical treatment, 2, 5 and ten years postoperatively. Two years after the surgery MRI examination of the shoulder joint is performed. All of the outpatient clinical evaluations during the study were performed by the orthopaedic surgeon blinded to the both groups of patients.

The actual therapy was as follows: open surgery was preceded by a standard diagnostic arthroscopy, which was performed from the posterior portal for optics and anterior portal for arthroscopic instruments. The tendons of the rotator cuff were assessed from both sides - intraarticular and subacromial. To evaluate cuff tendon injury perioperatively and to measure the rupture width, a special arthroscopic hook calibrated in 1 mm was used. To evaluate the shape of the rupture, the classification of Ellman - Gartsman was used. Surgical treatment of injured tendons of the rotator cuff was performed in the beach chair position of the patient, by the deltoid muscle split approach. After evaluation of the extent and location of the cuff tendon lesion the aspiration of 10 ml of bone marrow blood was done ( from the humeral head through the same surgical approach ) into a 20 mL syringe prefilled with 0.5 ml of heparin with the Yamshidi needle. Aspiration of the bone marrow was performed by surgeon. From one bone puncture was aspirated maximally 3 ml of marrow blood. Centrifugation of the aspirate in 10 ml test-tube Monovette filled with citrate followed. Selected centrifugation regime consisted of gradient 15 minute centrifugation at 200 g RCF ( relative centrifugal force ). After such a centrifugation the tube contents is divided into three parts. The upper layer consists of the platelet-rich plasma (PRP), the middle layer of the buffy coat with the dominant proportion of leukocytes, and the lower layer is formed by sedimented erythrocytes. Using a sterile laboratory pipette, a collection of the buffy coat was performed. MSCs represented 0.01 to 0.02 % of all nuclear elements of the buffy coat, that is about 10 x 106 / l. The MSCs concentrate ( similar to synovial fluid in consistency and colour ) was impregnated into the collagen patch Hypro-Sorb F ( Otrokovice, Czech Republic ) of dimensions 1x2 cm. The collagen patch as a carrier of the MSCs concentrate was used to ensure its retention in desired place. This material was then inserted between the tendon and bone, into the place of re-fixing of the rotator cuff tendons ( footprint ) before tightening the threads of the anchors. Fixation of the tendon to the bone was made by a double row method with use of absorbable fixation anchors BioComposite Corkscrew ( Arthrex, Munich, Germany ). In all such treated cases the tendon was fixed in place of original attachment without any stress and without the need of abduction of the arm above 60 degrees. All patients underwent Neer acromioplasty for an increase of the subacromial space. This procedure was followed by the standard surgical wound closure in all anatomical layers, sterile dressing of the wound and by applying of the abduction orthosis. All patients were operated by the same orthopaedic surgeon with the same surgical technique. Open surgery instead of arthroscopy was chosen because of the safer fixation of the MSCs carrier under the re-inserted tendon and to reduce the risk of washout of the MSCs concentrate from the carrier during the arthroscopy.

Surgical treatment of patients in Group II was identical as in Group I, except the aspiration of bone marrow from the humeral head and subsequent application of the scaffold saturated with MSCs into the tendon / bone interface.

Abduction fixation lasted for 4 weeks. Passive motion over the horizontal line under the guidance of a physiotherapeutist was initiated the first postoperative day. After removing the fixation, an active rehabilitation began, that is a full range of motion exercises done actively 6 weeks after surgery. Full load was allowed 12 weeks after the surgery.

Outpatient follow-up took place according to the schedule mentioned above. To check the integrity of the tendon at the point of insertion into the greater tuberosity of the humerus, MRI of the shoulder joint was performed 2 years postoperatively. Both, preoperative and postoperative MRI examinations were performed with a 1.5T high-field scanner, in sagittal, coronal, and axial planes, in T1- and T2-weighted fat-saturated sequences ( MRI arthrography using gadollinium as a contrast medium ). All of MRI results were evaluated by an experienced radiologist specialized in musculoskeletal pathologies. He evaluated tendon integrity, presence and localisation of complete retear, tendon and muscle borders, and presence of abnormal artifacts.

The primary hypothesis of this study is that the use of mesenchymal stem cells in the supraspinatus tendon reconstruction surgery will have a positive effect in the assessment of both subjective and objective scoring systems, and also in terms of reducing the number of tendon reruptures compared to the patients population in which mesenchymal stem cells were not used. All data were statistically analyzed with STATISTICA 9.0 programme. To compare the results of the of the VAS score, the Constant score, and the ASES score preoperatively and one year after the surgery Student´s t- test was used, to compare the incidence of reruptures between both groups of patients 2 years postoperatively Chi-square test was used. The significance level was determined at p \<0.05. Patients were randomly assigned to one of the treatment possibilities with use of the Random Number Generator Software 7.0 by the method 1:1