Osteoinductive potential and periimplant bone formation of immobilized rhBMP-2 on titanium implants in a gap healing model in sheep

Tom Norman's show with banner for 'Tommy 'Toes' Jacobsen/Armless Pianist/Electronic Organist' photographed at Oxford St Giles Fair, 1957

Phloroglucinol-enhanced whey protein isolate hydrogels with antimicrobial activity for tissue engineering

Aging populations in developed countries will increase the demand for implantable materials to support tissue regeneration. Whey Protein Isolate (WPI), derived from dairy industry by-products, can be processed into hydrogels with the following desirable properties for applications in tissue engineering: (i) ability to support adhesion and growth of cells; (ii) ease of sterilization by autoclaving and (iii) ease of incorporation of poorly water-soluble drugs with antimicrobial activity, such as phloroglucinol (PG), the fundamental phenolic subunit of marine polyphenols. In this study, WPI hydrogels were enriched with PG at concentrations between 0 and 20% w/v. PG solubilization in WPI hydrogels is far higher than in water. Enrichment with PG did not adversely affect mechanical properties, and endowed antimicrobial activity against a range of bacteria which occur in healthcare-associated infections (HAI). WPI-PG hydrogels supported the growth of, and collagen production by human dental pulp stem cells and - to a lesser extent - of osteosarcoma-derived MG-63 cells. In summary, enrichment of WPI with PG may be a promising strategy to prevent microbial contamination while still promoting stem cell attachment and growth

Histologische Untersuchungen von Bone-Morphogenetic-Protein-2-beschichteten Titanimplantaten im Mittelohr des Kaninchens.

Einleitung: Die osteoinduktive Potenz von rekombinantem humanen knochenmorphogenetischen Protein-2 (rhBMP-2) konnte bisher für Lamellenknochen nachgewiesen werden. Einzelne Erfahrungen für das Mittelohr liegen im Tierversuch für lösliches rhBMP-2 vor. Kürzlich ist es gelungen, durch Oberflächenmodifikation von Titanoberflächen rhBMP-2 kovalent auf diesen zu binden. Methoden und Ergebnisse: Bei 18 Kaninchen (36 Mittelohren) wurde durch Spaltüberbrückungsversuche die Knochenneubildung (Dünnschliffpräparate, digitale Morphometrie) in Implantatnähe erfasst für 1.: Titanimplantate und Zugabe von löslichem rhBMP-2, 2.: rhBMP-2-beschichtete- und 3.: Kontroll-Implantate. Hierbei konnte die verbesserte Osseointegration von rhBMP-2-beschichteten Titanimplantaten im Mittelohr nachgewiesen werden. Schlussfolgerungen: Erstmals wurde die Wirksamkeit rhBMP-2-beschichteter Titan-Implantate im Mittelohr nachgewiesen. Zukünftige Untersuchungen müssen den Stellenwert solcher Implantate für die rekonstruktive Mittelohrchirurgie (Ossikelrekonstruktion, Obliterationen, Rekonstruktion der hinteren Gehörgangswand) evaluieren

Chitosan/gelatin scaffolds support bone regeneration

Chitosan/Gelatin (CS:Gel) scaffolds were fabricated by chemical crosslinking with glutaraldehyde or genipin by freeze drying. Both crosslinked CS:Gel scaffold types with a mass ratio of 40:60% form a gel-like structure with interconnected pores. Dynamic rheological measurements provided similar values for the storage modulus and the loss modulus of the CS:Gel scaffolds when crosslinked with the same concentration of glutaraldehyde vs. genipin. Compared to genipin, the glutaraldehyde-crosslinked scaffolds supported strong adhesion and infiltration of pre-osteoblasts within the pores as well as survival and proliferation of both MC3T3-E1 pre-osteoblastic cells after 7 days in culture, and human bone marrow mesenchymal stem cells (BM-MSCs) after 14 days in culture. The levels of collagen secreted into the extracellular matrix by the pre-osteoblasts cultured for 4 and 7 days on the CS:Gel scaffolds, significantly increased when compared to the tissue culture polystyrene (TCPS) control surface. Human BM-MSCs attached and infiltrated within the pores of the CS:Gel scaffolds allowing for a significant increase of the osteogenic gene expression of RUNX2, ALP, and OSC. Histological data following implantation of a CS:Gel scaffold into a mouse femur demonstrated that the scaffolds support the formation of extracellular matrix, while fibroblasts surrounding the porous scaffold produce collagen with minimal inflammatory reaction. These results show the potential of CS:Gel scaffolds to support new tissue formation and thus provide a promising strategy for bone tissue engineering. © 2018, Springer Science+Business Media, LLC, part of Springer Nature

Analysis of gelatin secondary structure in gelatin/keratin-based biomaterials

The possibility of using protein-based materials as cellular scaffold strongly depends on protein conformation, and several attempts have been made by researchers to obtain scaffold with morphology miming the extracellular matrix. It is widely recognized that the secondary structure of proteins affects the mechanical and biological properties of protein-based scaffolds. However, few studies have been published, and an exhaustive explanation is still missing. In this work the study of the gelatin structure in gelatin-based materials and the investigation of the possible correlations between structure, mechanical and biological features is reported. We have examined how the secondary structure of gelatin is affected (i) by the process used to obtain the biomaterials (solvent casting vs. electrospinning), (ii) by the concentration of cross linker (3-(Glycidyloxypropyl)trimethoxysilane) (GPTMS), and (iii) by the raw keratin extract added. Gelatin electrospun materials have shown a content of ordered structure higher than gelatin casted films, likely due to the random coil – α-helix transition occuring during electrospinning. GPTMS gives a decrease of ordered structures in gelatin casted films (random structure increasing from 20% to 60%), while it does not affect the percentage of ordered structure in electrospun samples. In the gelatin/keratin electrospun biomaterials, the presence of keratin produces a decrease of α-helix content from 31% to 2–15% and an increase of β-structures, promoting the conversion from antiparallel to parallel β-sheet. The structure of gelatin affects the mechanical performances of biomaterials. In gelatin/keratin electrospun biomaterials we have found a positive correlation between failure strain and helix conformation and a negative correlation with β-structures. Elastic modulus has opposite correlations. All gelatin-based biomaterials have been tested as scaffold for pre-osteoblastic cells showing good biocompatibility for both casted films and electrospun biomaterials

Mineralized self-assembled peptides on 3D laser-made scaffolds: a new route toward 'scaffold on scaffold' hard tissue engineering

In this study, we propose a new approach to hard tissue regeneration based on the mineralization of 3D scaffolds made using lasers. To this end, we report the rational design of aspartate-containing self-assembling peptides targeted for calcium binding. We further investigate the suitability of these peptides to support cell attachment and proliferation when coupled on a hybrid organic-inorganic structurable material, and evaluate the response of pre-osteoblastic cells on functionalized 3D scaffolds and material surfaces. Our results show that the mineralized peptide, when immobilized on a hybrid photo-structurable material strongly supports cell adhesion, a proliferation increase after three and seven days in culture, and exhibits a statistically significant increase of biomineralization. We propose this strategy as a 'scaffold on scaffold' approach for hard tissue regeneration