Physicochemical and Biological Characterization of Gelatin/Alginate Scaffolds Reinforced with β -TCP, FDBA, and SrHA: Insights into Stem Cell Behavior and Osteogenic Differentiation

Bone tissue engineering necessitates the development of scaffolds with optimal properties to provide a suitable microenvironment for cell adhesion, proliferation, and osteogenic differentiation. The selection of appropriate scaffold materials remains a critical challenge in this field. In this study, we aimed to address this challenge by evaluating and comparing the performance of hydrogel scaffolds reinforced with -tricalcium phosphate ( -TCP), allograft, and a combination of allograft and strontium hydroxyapatite (SrHA). In this study, scaffolds containing the following compounds with a weight ratio of 75 : 25 : 50 were made using a 3D printer: group (1) alginate + gelatin + -TCP (TCP), group (2) alginate + gelatin + allograft (Allo), and group (3) alginate + gelatin + allograft + strontium hydroxyapatite (Str). Stem cells extracted from rat bone marrow (rBMSCs) were cultured on scaffolds, and cell proliferation and differentiation tests were performed. Also, the physical and chemical properties of the scaffolds were investigated. The two/one-way analysis of variance (ANOVA) by Tukey's post hoc test was performed. There was no significant difference between scaffolds with pore size and porosity. TCP scaffolds' mechanical strength and degradation rate were significantly lower than the other two groups ( < 0.05). Also, the swelling ratio of Allo scaffolds was higher than in other samples. The amount of cell proliferation in the samples of the TCP group was lower than the other two, and the Allo samples had the best results in this concern ( < 0.01). However, the scaffolds containing strontium hydroxyapatite had significantly higher bone differentiation compared to the other two groups, and the lowest results were related to the scaffolds containing -TCP. Hydrogel scaffolds reinforced with allograft or its combination with strontium showed better physicochemical and biological behavior compared to those reinforced with -TCP. Besides, adding strontium had a limited impact on the physicochemical features of allograft-containing scaffolds while improving their potential to induce osteogenic differentiation.