Gelatin‐coating increases in‐vivo bone formation capacity of three‐dimensional 45S5‐bioactive glass‐based crystalline scaffolds

Abstract

Recent studies have demonstrated that surface characteristics, porosity, and mechanical strength of three‐dimensional 45S5‐type bioactive glass (BG)‐based scaffolds are directly correlated with osteogenic properties. Three‐dimensional BG‐based scaffolds obtained from maritime natural sponges (MNSs) as sacrificial templates exhibit the required morphological properties; however, no in vivo data about the osteogenic features are available. In this study, uncoated (Group A) and gelatin‐coated (Group B) crystalline MNS‐obtained BG‐based scaffolds were evaluated mechanically and seeded with human mesenchymal stem cells prior to subcutaneous implantation in immunodeficient mice. Before implantation and after explantation, micro‐computed tomography scans were conducted, and scaffolds were finally subjected to histomorphometry. Scaffolds of both groups showed bone formation. However, Group B scaffolds performed distinctly better as indicated by a significant increase in scaffold volume (8.95%, p = 0.039) over the implantation period compared with a nonsignificant increase of 5.26% in Group A scaffolds in micro‐computed tomography analysis. Furthermore, percentage bone area was 10.33% (±1.18%) in the Group B scaffolds, which was significantly (p = 0.007) higher compared with the 8.53% (±0.77%) in the Group A scaffolds in histomorphometry. Compressive strength was enhanced significantly by gelatin coating (9 ± 2 vs. 4 ± 1 MPa; p = 0.029). The presence of gelatin on the remnant parts was verified by scanning electron microscopy and X‐ray spectroscopy, demonstrating the coatings' resilience. MNS‐obtained BG‐based scaffolds were thus confirmed to exhibit osteogenic properties in vivo that can significantly be enhanced by gelatin coating.

Bioactive Glass (BG) ICIE16 Shows Promising Osteogenic Properties Compared to Crystallized 45S5-BG

“…The intention behind this approach was to generate basic in vitro data of both BGs with the option to transfer both BGs to in vivo settings. When used in vivo, BGs are often applied as scaffolds, for example, 3D engineered constructs that require sintering (a high temperature fabrication process) for their production [8,[17][18][19]].…”

Supplementation with 45S5 Bioactive Glass Reduces In Vivo Resorption of the β-Tricalcium-Phosphate-Based Bone Substitute Material Vitoss

“…Four scaffolds each were implanted subcutaneously into female SCID mice (CB17/Icr-Prkdcscid/Crl; Charles River, Sulzfeld, Germany) using a well-known protocol [32,60,61,62,63]. Under general inhalation anesthesia with isoflurane and under sterile conditions, two subcutaneous pouches each were created by skin incision and blunt dilation bilaterally over the back at the level of the anterior and posterior limbs, followed by implantation of the scaffold and suture of the skin.…”

“…During scanning, the scaffolds were stored in PBS. The resulting datasets were reconstructed using NRecon (Version 1.6.9.8, Bruker micro-CT, Kontich, Belgium) and were analyzed by Heidelberg-mCT-Analyzer in order to monitor changes in the TIV over the implantation period as a marker for resorption of the scaffold following previously published protocols [62,63]. For representative 3D visualization, reconstructed datasets were opened in CTVox (Version 3.1, Bruker micro-CT, Kontich, Belgium) and volume rendered after grey-value alignment using the onboard algorithms of the program.…”

“…Osteoid formation within the scaffolds was quantitatively assessed by Movat’s pentachrome staining which allows for detailed discrimination between the osteoid and the “non-osteoid” tissue, as published previously [60,63,64]. The area of osteoid was divided by the whole scaffold area and expressed as percentage osteoid area per scaffold area, as described elsewhere [61].…”

“…On the other hand, osteoblast precursors from the host invade the scaffold and play a role in osteoid formation. Therefore, in situ hybridization was performed on representative slides in order to assess the origin of the cells responsible for osteoid formation following previously published protocols [63,65]. In short, sections were deparaffinized, rehydrated, and digested by Proteinase K (Thermo Fisher Scientific, Dreieich, Germany) before characterizing host tissue by marked murine-specific genomic short interspersed nucleotide elements (mSINE) or MSC-derived tissue by marked human Alu elements (hALU).…”