Aging impairs osteoblast differentiation of mesenchymal stem cells grown on titanium by favoring adipogenesis

ABSTRACT Aging negatively affects bone/titanium implant interactions. Our hypothesis is that the unbalance between osteogenesis and adipogenesis induced by aging may be involved in this phenomenon. Objective We investigated the osteoblast and adipocyte differentiation of mesenchymal stem cells (MSCs) from young and aged rats cultured on Ti. Material and Methods Bone marrow MSCs derived from 1-month and 21-month rats were cultured on Ti discs under osteogenic conditions for periods of up to 21 days and osteoblast and adipocyte markers were evaluated. Results Cell proliferation, alkaline phosphatase (ALP) activity, extracellular matrix mineralization and gene expression of RUNX2, osterix, ALP, bone sialoprotein, osteopontin, and osteocalcin were reduced in cultures of 21-month rats compared with 1-month rats grown on Ti. Gene expression of PPAR-γ , adipocyte protein 2, and resistin and lipid accumulation were increased in cultures of 21-month rats compared with 1-month rats grown on the same conditions. Conclusions These results indicate that the lower osteogenic potential of MSCs derived from aged rats compared with young rats goes along with the higher adipogenic potential in cultures grown on Ti surface. This unbalance between osteoblast and adipocyte differentiation should be considered in dental implant therapy to the elderly population.

A standardized research protocol for platelet-rich plasma (PRP) preparation in rats

Introduction: The urgent need for studies using standardized protocols to evaluate the real biological effects of PRP has been emphasized by several authors. Objective: The purpose of this study was to standardize a methodology for autologous Platelet-Rich Plasma (PRP) preparation in rats. Material and methods: Twenty-four, 5 to 6-month-old, male rats, weighing 450 to 500 g were used. After general anesthesia, 3.15 ml of blood was collected from each animal, via cannulation of the jugular vein. A standardized technique of double centrifugation was used to prepare PRP. PRP samples and peripheral blood platelets were then manually counted using a Neubauer chamber. Student’s t-test was used to compare the differences between the number of platelets in peripheral blood and PRP samples (p < 0.05). In addition, PRP and peripheral blood smears were stained to see platelets’ morphology. Results: All surgical procedures were well tolerated by the animals and they were healthy during the entire experimental period. PRP samples showed higher significantly platelet concentrations than peripheral blood samples (2,677,583 and 683,680 respectively). Conclusion: Within the limits of this study, it can be concluded that the method used produced autologous PRP with appropriated platelet quantity and quality, in rats.