*Article* **Osteogenic Effect of ZnO-Mesoporous Glasses Loaded with Osteostatin**

**Rebeca Pérez 1, Sandra Sanchez-Salcedo 1,2, Daniel Lozano 1,2, Clara Heras 1, Pedro Esbrit 1,3, María Vallet-Regí 1,2 and Antonio J. Salinas 1,2,\***


Received: 5 July 2018; Accepted: 1 August 2018; Published: 4 August 2018

**Abstract:** Mesoporous Bioactive Glasses (MBGs) are a family of bioceramics widely investigated for their putative clinical use as scaffolds for bone regeneration. Their outstanding textural properties allow for high bioactivity when compared with other bioactive materials. Moreover, their grea<sup>t</sup> pore volumes allow these glasses to be loaded with a wide range of biomolecules to stimulate new bone formation. In this study, an MBG with a composition, in mol%, of 80% SiO2–15% CaO–5% P2O5 (Blank, BL) was compared with two analogous glasses containing 4% and 5% of ZnO (4ZN and 5ZN) before and after impregnation with osteostatin, a C-terminal peptide from a parathyroid hormone-related protein (PTHrP107-111). Zn2+ ions were included in the glass for their bone growth stimulator properties, whereas osteostatin was added for its osteogenic properties. Glasses were characterized, and their cytocompatibility investigated, in pre-osteoblastic MC3T3-E1 cell cultures. The simultaneous additions of osteostatin and Zn2+ ions provoked enhanced MC3T3-E1 cell viability and a higher differentiation capacity, compared with either raw BL or MBGs supplemented only with osteostatin or Zn2+. These in vitro results show that osteostatin enhances the osteogenic effect of Zn2+-enriched glasses, suggesting the potential of this combined approach in bone tissue engineering applications.

**Keywords:** mesoporous glasses; ZnO-additions; osteostatin loading; osteosteoblast cell cultures; osteogenic effect
