Calcium phosphate foam
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The present method describes the procedure to fabricate calcium phosphate foams with suitable open porosity, pore size, and composition to perform three-dimensional (3D) cell cultures with the objective to simulate the bone tissue microenvironment in vitro. Foams with two compositions but equivalent porosity can be fabricated. On the one hand, hydroxyapatite foams obtained by hydrolysis at 37 °C, with microstructure that mimics the small crystal size of the mineral component of bones, and on the other hand, beta tricalcium phosphate foams with polygonal grains obtained by sintering at 1100 °C. In the first part of the chapter the calcium phosphate foams are briefly described. Afterwards, the foaming process is described in detail, including alternatives to overcome processing problems than can arise. Finally, insights are provided on how to perform 3D cell cultures using the calcium phosphate foams as substrates.
- MeSH
- biologické modely * MeSH
- buněčné kultury MeSH
- buněčné mikroprostředí MeSH
- fosforečnany vápenaté chemie MeSH
- kosti a kostní tkáň cytologie MeSH
- krysa rodu rattus MeSH
- poréznost MeSH
- testování materiálů MeSH
- tkáňové inženýrství metody MeSH
- tkáňové podpůrné struktury chemie MeSH
- velikost částic MeSH
- vyrobené materiály MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
In this study, a reproducible method of fabricating hierarchically 3D porous scaffolds with high porosity and pore interconnectivity is reported. The method is based on in-situ foaming of a dispersion of diisocyanate, polyol, water and hydroxyapatite (HA) to form a hard foamed HA/polyurethane composite which after heat treatment provided a bi-phase calcium phosphate scaffold. This technique, combining the advantages of polymer sponge and direct foaming methods, provides a better control over the macrostructure of the scaffold. A modification of the multi-scaled porous macrostructure of scaffolds produced by changing the ratio of input reactants and by sintering temperature was studied. The pore morphology, size, and distribution were characterized using a scanning electron microscope and mercury porosimetry. The pores were open and interconnected with multi-scale (from several nanometres to millimetres) sizes convenient for using in tissue engineering applications. The bioactivity was confirmed by growing an apatite layer on the surfaces after immersion in simulated body fluid. The material was biocompatible, as shown by using normal human adipose tissue-derived stem cells (ASC). When seeded onto the scaffolds, the ASC adhered and remained healthy while maintaining their typical morphology.
Collagen I-based foams were modified with calcined or noncalcined hydroxyapatite or calcium phosphates with various particle sizes and pores to monitor their effect on cell interactions. The resulting scaffolds thus differed in grain size, changing from nanoscale to microscopic, and possessed diverse morphological characteristics and resorbability. The materials' biological action was shown on human bone marrow MSCs. Scaffold morphology was identified by SEM. Using viability test, qPCR, and immunohistochemical staining, we evaluated the biological activity of all of the materials. This study revealed that the most suitable scaffold composition for osteogenesis induction is collagen I foam with calcined hydroxyapatite with a pore size of 360 ± 130 μm and mean particle size of 0.130 μm. The expression of osteogenic markers RunX2 and ColI mRNA was promoted, and a strong synthesis of extracellular protein osteocalcin was observed. ColI/calcined HAP scaffold showed significant osteogenic potential, and can be easily manipulated and tailored to the defect size, which gives it great potential for bone tissue engineering applications.
The purpose of the present work was to evaluate in vivo different antimicrobial therapies to eradicate osteomyelitis created in the femoral head of New Zealand rabbits. Five phosphate-based cements were evaluated: calcium phosphate cements (CPC) and calcium phosphate foams (CPF), both in their pristine form and loaded with doxycycline hyclate, and an intrinsic antimicrobial magnesium phosphate cement (MPC; not loaded with an antibiotic). The cements were implanted in a bone previously infected with Staphylococcus aureus to discern the effects of the type of antibiotic administration (systemic vs. local), porosity (microporosity, i.e. <5 μm vs. macroporosity, i.e. >5 μm) and type of antimicrobial mechanism (release of antibiotic vs. intrinsic antimicrobial activity) on the improvement of the health state of the infected animals. A new method was developed, with a more comprehensive composite score that integrates 5 parameters of bone infection, 4 parameters of bone structural integrity and 4 parameters of bone regeneration. This method was used to evaluate the health state of the infected animals, both before and after osteomyelitis treatment. The results showed that the composite score allows to discern statistically significant differences between treatments that individual evaluations were not able to identify. Despite none of the therapies completely eradicated the infection, it was observed that macroporous materials (CPF and CPFd, the latter loaded with doxycycline hyclate) and intrinsic antimicrobial MPC allowed a better containment of the osteomyelitis. This study provides novel insights to understand the effect of different antimicrobial therapies in vivo, and a promising comprehensive methodology to evaluate the health state of the animals was developed. We expect that the implementation of such methodology could improve the criteria to select a proper antimicrobial therapy.
- MeSH
- antibakteriální látky aplikace a dávkování farmakokinetika farmakologie MeSH
- doxycyklin aplikace a dávkování farmakologie MeSH
- femur diagnostické zobrazování patologie MeSH
- fosforečnany vápenaté chemie MeSH
- implantované léky chemie farmakologie MeSH
- infekční nemoci kostí farmakoterapie terapie MeSH
- kostní cementy chemie farmakologie MeSH
- králíci MeSH
- lékové transportní systémy metody MeSH
- osteomyelitida farmakoterapie terapie MeSH
- poréznost MeSH
- regenerace kostí účinky léků MeSH
- stafylokokové infekce farmakoterapie terapie MeSH
- uvolňování léčiv MeSH
- viskoelastické látky chemie MeSH
- výsledek terapie MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
