Effect of rat bone marrow derived-stem cell delivery from serum-loaded oxidized alginate-gelatin-biphasic calcium phosphate hydrogel for bone tissue regeneration using a nude mouse critical-sized calvarial defect model

Blood serum contains various kinds of proteins which are necessary for tissue repair and regeneration process. Defect healing of fractured bone is initiated by the influx of blood and then clot formation. Thus, proteins in serum may have the ability to stimulate the bone regeneration process. In this work, we investigated the fabrication of serum-loaded oxidized alginate-gelatin-biphasic calcium phosphate hydrogels with various contents of blood serum (0%, 5%, 10%, and 15% in % v/v) to evaluate the stimulatory effect of serum proteins on bone regeneration. This system was also evaluated for rat bone marrow-derived stem cell delivery to get faster bone healing. The serum-loaded oxidized alginate-gelatin-biphasic calcium phosphate hydrogel samples were characterized by scanning electron microscopy, porosity meter, X-ray diffraction, and Fourier transform infrared for morphology and phase characterization together with their mechanical behavior. Protein release behavior, degradation, and swelling of the samples were studied. In vitro study was performed using bone marrow-derived stem cells to study cell attachment, viability, and proliferation. These studies revealed the best cell attachment and highest proliferation for 5% serum-loaded oxidized alginate-gelatin-biphasic calcium phosphate hydrogel scaffold. This composition also showed the ability to deliver stem cell in the defect zone which significantly improved the bone regeneration extent found in the in vivo animal model. In vivo study revealed that for the critical 5-mm calvarial defect into nude mouse skull, the 5% serum-loaded sample with bone marrow-derived stem cells shows the best bone regeneration potential.