Thermogel scaffold application in combination with mesenchymal stem cells in the treatment of joint cartilage injuries

There is a growing awareness of the role of tissue scaffolds that can be applied in one session to overcome the limitations of cell-based tissue engineering techniques such as Matrix-induced autologous chondrocyte implantation (MACI) in the treatment of joint cartilage injuries and to regenerate the joint surface. In the treatment of cartilage lesions, the notion that the application of tissue scaffolds together with microfractures does not provide sufficient cell density has led to the idea of applying Bone Marrow Aspiration Concentrates (BMAC) together with tissue scaffolds. In addition to the clinical results in the literature, there is no information in the literature regarding the changes in the structural properties of the tissue scaffolding that the addition of cells to tissue scaffolds with different characteristics depending on the production process and content. In the current study, it was aimed to produce a chitosan-based tissue scaffold, which is liquid at room temperature, which is called thermogel, and has the property of gelating at body temperature in the joint environment where it is applied, the gelation state and biomechanical properties, and the possible effects of adding bone marrow aspiration concentrate on these properties. First of all, Chitosan solution (5 mL, pH ∼ 5.6) for gelation is mixed with different amounts of ammonium hydrogen phosphate (AHP) (0.05, 0.075, 0.10, 0.15 g). The concentration of AHP capable of gelling at 37 ° C within 10 minutes was determined. Then, the biomechanical properties of cell-free and cellular tissue scaffolds that gelled by providing gelation in cadaver sheep knees at the determined concentration were evaluated in compression mode using the CellScale Univert Biomaterial Tester (CellScale, Canada). It was determined that gelling was achieved with the minimum AHP level within the desired 10 minutes for gelling, with 0.075 g. Young's modulus of 3 cell-free tissue scaffolds selected in Group 1 were calculated as 0.215, 0.2282 and 0.2617, respectively. Young's modulus of the 3-cell tissue scaffold selected in Group 2 was calculated as 0.0992, 0.2749 and 0.2109, respectively. The average Young's Modulus value was calculated as 0.235 ± 0.024 for Group 1 cell-free tissue scaffolds and 0.195 ± 0.089 for Group 2 celled tissue scaffolds. Although the Young's Modulus value was high in the cell-free group, this difference between the two groups was not statistically significant (p = 0.247). In the light of the data obtained from the study, it is thought that the addition of BMAC may not make a significant difference in the biomechanical properties of the thermogel tissue scaffold.