CHANGES IN MARKERS OF BONE TISSUE REMODELING AND THE INFLAMMATORY PROCESS IN THE BLOOD SERUM OF WHITE RATS IN CASE OF DEFECT FILLING OF THE FEMUR WITH IMPLANTS BASED ON POLYLACTIDE AND TRICALCIUMPHOSPHATE WITH MESENCHYMAL STEM CELLS

Objective. Based on the analysis of markers of inflammation and metabolism of bone tissue in the blood serum of laboratory rats, to evaluate the course of bone remodeling after filling the defect in the distal metaphysis of the femur with 3D-printed implants based on polylactide and tricalcium phosphate (3D-I) alone or in combination with mesenchymal stromal cells (MSCs). Methods. 53 white rats were used, which were divided into groups: intact (5 animals) — the operation was not performed; Control (15) — 3D-I; Experiment I (15) — 3D-I + cultured alloMSCs; Experiment II (15) — 3D-I + introduction of alloMSCs into the area of surgical intervention 7 days after implantation. The following were studied: the content of glycoproteins (GP), interleukin-6 (IL-6), osteocalcin, chondroitin sulfates (CS), total protein, calcium, alkaline (AlP) and acid phosphatase (AP) activity, and their ratio, mineralization indices were calculated. Results. Compared with intact animals, higher indicators were determined in the rats of the Control group: the content of GP by 39.73; 32.88; 23.29 %; CS — 250.00; 222.09 and 196.51 %, AlP activity — 81.67, 51.03, 39.36 %, on the 15th, 30th, and 90th days of the experiment; IL-6 — 44.89; 60.06 % on the 15th and 30th days. In the rats of the Experiment I g roup: the content of GP — by 82.19; 65.75, 57.53 %, IL-6 — 72.14; 96.59; 79.88 %, CS — 306.98; 276.74; 253.49 %; AlP activity — 63.73; 129.70; 51.28 %, on the 15th, 30th and 90th days of the experiment. In the Experiment II group: on the 15th, 30th and 90th days, the content of GP was higher by 27.40; 26.03; 129.18 %; CS — by 175.58; 137.21 and 115.12 %; AlP activity — 192.99; 178.02, 76.31 %; on the 15th and 30th days: IL-6 — by 37.46; 20.74 %. Conclusions. In the case of filling the defect with 3D-printed implants, biochemical signs of moderate inflammation were determined; 3D-printed implants together with MSCs — pronounced inflammation, slowing of bone formation, formation of connective tissue; 3D-printed implants with postoperative injection of MSCs — moderate inflammation and optimal conditions for healing the defect with bone tissue.