Endoscopic treatment of Barrett's oesophagus often leads to further damage of healthy tissue causing fibrotic tissue formation termed as strictures. This study shows that synthetic, self-assembling peptide hydrogels (PeptiGelDesign) support the activity and function of primary oesophageal cells, leading to epithelialization and stratification during in vitro 3D co-culture. Following buffering in culture media, rat oesophageal stromal fibroblasts (rOSFs) are incorporated into a library of peptide hydrogels, whereas mouse oesophageal epithelial cells (mOECs) are seeded on the surface. Optimal hydrogels (PGD-AlphaProC and PGD-CGD2) support mOEC viability (>95%), typical cell morphology (cobblestone-like), and slower migration over a shorter distance compared to a collagen control, at 48 h. Positive expression of typical epithelial markers (ZO-1 and cytokeratins) is detected using immunocytochemistry at day 3 in culture. Furthermore, optimal hydrogels are identified which support rOSF viability (>95%) with homogeneous distribution when incorporated into the hydrogels and also promote the secretion of collagen type I detected using an enzyme linked immunosorbent assay (ELISA), at day 7. A 3D co-culture model using optimal hydrogels for both cell types supports a stratified epithelial layer (expressing involucrin and AE1/AE3 markers). Findings from this study could lead to the use of peptide hydrogels as a minimally invasive endoscopic therapy to manage oesophageal strictures.
Antimicrobial silver nanoparticle coatings have attracted interest for reducing prosthetic joint infection. However, few studies report in vivo investigations of the biotransformation of silver nanoparticles within the regenerating tissue and its impact on bone formation. We present a longitudinal investigation of the osseointegration of silver nanoparticle-coated additive manufactured titanium implants in rat tibial defects. Correlative imaging at different time points using nanoscale secondary ion mass spectrometry, transmission electron microscopy (TEM), histomorphometry, and 3D X-ray microcomputed tomography provided quantitative insight from the nano- to macroscales. The quality and quantity of newly formed bone is comparable between the uncoated and silver coated implants. The newly formed bone demonstrates a trabecular morphology with bone being located at the implant surface, and at a distance, at two weeks. Nanoscale elemental mapping of the bone-implant interface showed that silver was present primarily in the osseous tissue and colocalized with sulfur. TEM revealed silver sulfide nanoparticles in the newly regenerated bone, presenting strong evidence that the previously in vitro observed biotransformation of silver to silver sulfide occurs in vivo.
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