An Osteocartilaginous 3D Printing Implant Using a Biocompatible Polymer and Pre-Differentiated Mesenchymal Stem Cells in Sheep

(1) Background: Currently, there are no pharmacological treatments that can modify the course of osteoarthritis (OA). For this reason, the present work is focused on generating knowledge for the development of new therapeutic alternatives for the treatment of OA. The objective of this work was to develop an articular hybrid implant with mesenchymal stem cells (MSCs) from sheep. The cells were differentiated into cartilage and bone using a bioabsorbable polymer with 3D printing Technology. (2) Methods: MSCs pre-differentiated to chondrocytes and osteoblasts were seeded on the 3D-printed scaffolds using polylactic acid (PLA). These were later implanted for 3 months in the thoracic ribs area and for 6 months inside the femoral head and outside of the joint capsule. After recovery, we analyzed the expressions of specific markers for bone and cartilage in the implants (3) Results: After 3 months, in lateral implants, the expression for bone markers (OPN, RUNX2) was similar to that of the control; at 6 months, we obtained a higher expression of bone markers in the implants with pre-differentiated MCS to osteoblasts outside and inside the joint. For cartilage markers, three months after the placement of the lateral implant, the expressions of Aggrecan and SOX9 COL2A1 were similar to those of the control, but the expression of COL2A1 was less; at 6 months, the three cartilage markers SOX9, Aggrecan, and COL2A1 showed significant expressions in the implant inside joint with pre-differentiated MCS to chondrocytes. (4) Conclusions: In this study, we demonstrated that the presence of pre-differentiated MSCs in the implants was a determinant factor for the expression of bone- and cartilage-specific markers at three and six months. We managed to generate a practical and easy-to-implement articular surface repair model.